Investigation of the Analytical Properties Op

INVESTIGATION OF THE ANALYTICAL PROPERTIES

OP SUBSTITUTED ANTHRANILIC ACIDS AND RELATED COMPOUNDS

DISSERTATION

Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University

WILLIAM ALLEN YOUNG, B. A., K. Sc, The Ohio State University

1957

Approved, by:

Adviser Department of Chemistry ACKNOWLEDGEMENT

The author expresses his appreciation to Dr. T. R. Sweet for his suggestions and interest throughout this investigation and to the Kettering Research Foundation for sponsoring a portion of this work.

ii Table of Contents

Introduction “ Historical 2 Development of equations 4 Bjerrum's equations 4 Convergence correction 9 Schwarzenbach's graphical method 15 Calvin-Bjerrum pH titration equations 19 Experimental 30 The compounds and their preparations 30 Analysis of the compounds 36 The solvent medium 52 Titration procedures 54 Calibration of the pH meter 54 Study of ionic strength 57 Data 61 Discussion 170 Factors involved in chelate formation 170 Tables of results 178 Discussion of results 183 Properties and analytical uses 197 Summary 203 Appendix: Details of the preparations of the compounds 205 References 216

iii List of Tables

No. Page

1 Data for the convergence correction curve 11 2 Data for Schwarzenbach's method of solving k values for N,N' trimethylene dianthranilic acid 17

3 Elementary analysis of the nine prepared compounds 36

4 Equivalent weights of the compounds 37

5-11 Titration data for anthranilic acid 61 - 65

12 - 18 Titration data for N-methyl anthranilic acid 66 - 70

19 - 30 Titration data for 2 ,2 ' imino dibenzoic acid 72 - 82

31 - 41 Titration data for 2,2' hydrazo dibenzoic acid 33 _ go

42 - 53 Titration data for methylene dianthranilic acid 91 _ 99

54 - 69 Titration data for N,N' trimethylene dianthranilic acid 100 _ m

70 - 80 Titration data for N-(aiuinoethyl)-anthranilic acid 112 - 122

81 - 102 Titration data for 2 -(aminomethyl)-benzoic acid 124 - 136

103 - 108 Titration data for salicylic acid 137 - 141

109-119 Titration data for 0-(carboxymethoxy)-benzoic acid 142 - 148

120 - 130 Titration data for N-(carboxymethyl)-anthranilic acid I49 - 160

131 -141 Titration data for anthranilic acid diacetic acid 161 - 169

142 Acidity constants in 50 volume % dioxane .. 178

143 Formation constants of chelates in 50 volume a/o dioxane 179 _ 131

144 Orders of log for the five cations with each of the compounds 182

145 Chelate effects of N,N'ethylene dianthranilic acid 133

146 Chelate effects of N,Nrtrimethylene dianthranilic acid 186 147 Effect of adding -CH^COOH groups to the nitrogen of anthranilic acid 189 iv List of Figures

1 Convergence correction curve 2 Schwarzenbach method graph for N,N' trimethylene dianthranilic acid

15 Infrared spectra of the compounds

16 pH - a curve for anthranilic acid

17 pH - a curve for N-methyl anthranilic acid

18 n - pR curve for H-methyl anthranilic acid and zinc

19 pH - a curve for 2 ,2 ' iinino dibenzoic acid

20 n - pR curve for 2,2' imino dibenzoic acid and cobalt

21 n - pR curve for 2,2' imino dibenzoic acid and copper

22 pH - a curve for 2,2' hydrazo dibenzoic acid

23 pH - a curve for metnylene dianthranilic acid

24 n - pR curve for methylene dianthranilic acid and nickel

25 pH - a curve for N,h' trimethylene dianthranilic acid

26 pH - a curve for H-(aminoethyl)-anthranilic acid

27 pH - a curve for 2-(aminomethyl)-benzoic acid

28 n - pR curve for 2 -(aminomethyl)-benzoic acid and copper

29 pH - a curve for salicylic acid

30 pH - a curve for o-(carboxymethoxy)-benzoic acid

31 pH - a curve for N-(carboxymethyl)-anthranilic acid

v 32 n - pR curve for h-(carboxymethyl)-anthranilic acid 155 and copper

33 n - pR curve for N-(carboxymethyl)-anthranilic acid 159 and zinc

34 pH - a curve for anthranilic acid diacetic acid 163

35 n - pR curve for anthranilic acid diacetic acid 166 and nickel

36 Comparison of the stabilities of chelates of H-(amino- 191 ethyl)-anthranilic acid and N-(carboxymethyl)- anthranilic acid

37 Comparison of the stabilities of chelates of H-(amino- 192 ethyl)-anthranilic acid and ethylene dianthranilic acid

38 Comparison of the stabilities of chelates of H-(carooxy- 193 methyl)-anthranilic acid and H,N' ethylene dianthranilic acid

39 Comparison of the stabilities of chelates of 194 N,l\f' trimethylene dianthranilic acid and iJ,H' ethylene dianthranilic acid

40 Comparison of the log values of 2-(aminomethyl)- 195 benzoic with the second ionization potentials of the metals

41 Comparison of the log k^ values of anthranilic acid 196 diacetic acid with the second ionization potentials of the metals

vi INTRODUCTION

This investigation is one of a group of studies which have been carried out in this laboratory. These studies are concerned with the analytical properties of anthranilic acid, substituted anthranilic acids, derivatives of anthranilic acid, and compounds similar to anthranilic acid. The data obtained should be useful in determing the factors which cause certain analytical organic reagents to be specific or selective ana in the development of analytical methods. The present A'ork is a study of the effects of substitution on the amino group of anthranilic acid. A number of N-substituted anthranilic acids were prepared and acidity constants of these compounds were determined, formation constants of the chelates formed with each of these compounds and a series of transition met;. Is were obtained. In addition to the determination of constants, precipitation and color reactions of these compounds were studied.

1 HISTORICAL

The analytical uses of anthranilic acid have been reviewed by- Harris in his dissertation (l). he made a precipitation study which generally confirmed the earlier results found by Goto (2 ). Harris determined the acidity and formation constants of ring-substituted anthranilic acids (l, 3 , 4 ), including 5-sulfo anthranilic acid, 3 -methyl ■anthranilic acid, and 3 ,5-diiodo anthranilic acid. In addition he determined constants for anthranilic acid, li-methyl anthranilic acid, and il-pheriyl anthranilic acid (1,4). Harris prepared N,N' ethylene dianthranilic acid and found that it has constants and other properties which are quite different from anthranilic acid (5) Zhdanov, Tseitlin, and Yakubov (6) described direct amperometric titrations of copper, zinc, nickel, and cobalt using a solution of the sodium salt of anthranilic acid as the titrant. Cimemo.n and belser (7) studied the q u m t i tative broraination of anthranilic acid and gave an exact micro method for the determine tions of metals precipitated by anthranilic acid. Holmes end Crinr.in (o) studied an oxidation titration with nerchloretocerote a.is alr.o a colorj metric reaction as means of deter mining the anthranilic acin liber ted from metal aut.ranilc.tes dissolved in acid. Harris (l,3) and Zehner (9,10), studied 5-sulfo anthranilic acid. Zehner developed a spectrophotometric determination of iron usin. this reagent. Romero (ll) investigated the properties of several bromine and iodine-substituted anthranilic acids as gravimetric reagents. Salyer (12) used radiotracer techniques to measure the solu bilities of the cobalt precipitates of some of the reagents mentioned above. Datta and Banerjee (13) used N-(carboxymethyl)—anthranilic acid as a precipitant for tuorivmi. fi&ny of the properties of anthr nilic acid diacetic acid have been investigated by 3chw .roenbaeh (l4, 15, 16, 17). Fitch and

2 3 Russell (is) tested it as an eluent for rare earths. 2,2'Imino dibenzoic acid has been suggested as an oxidation reduction indicator (19, 20). The solvent medium used in our titration studies was 50 volume % dioxane-water, and it has also been used by many other workers in this field (21, 22, 23). J. K. Thompson and G. L. Wilson of Queen's University, Belfast, Ireland, presented a paper entitled "Metal-Organic Complexes of Analy tical Significance: Stabilities of Complexes of Bivalent Cations with Anthranilic Acid and Its Derivatives" at the XVth International Congress of Pure and Applied Chemistry at Lisbon, Portugal, during the week, September 9-16, 1956 (2 4 ). At the present time (February, 1957) no other details are available. Development of the equations used to calculate the formation constants.

Bjerrum (2 5) originally developed the theoretical equations for simple complexes; however, the treatment is the same for chelate complexes. When a metal ion M can react with ligands R, and N is the maximum number of ligands which can become attached to 1*1, then the following stepwise equilibria exist.

M + R ^ MR kx = /mR_7/Z"m_7 Z"\7 (i)

MR + R £ MR2 k 2 = D^gJ/D^J DO (II)

% _ 1 + R < kM - (III)

The quantity n is by definition the average number of ligands bound per metal.

n = D O + + n /mRmJ' ------(XV) DO + D m J + Z*®2_7 + D ^ y J +

Use of equations (i), (ll), and (ill) makes possible the elimination of the quantities DO, O D ^ O D ^ 7 from equation (IV). n = \ D O + Zkjk^IiO2 "* + Hk ^ . . . k j ^ X T 11 ------:------(v)

1 + ^ D O + ^ k ^ K j 2 •••• + kxk2 ••• k / X /

In terms of experimentally measured quantities, n can oe written as n =Ca - / \ 7 (VI)

is the total concentration of all metal species, and is the total concentration of all ligand species. C,„ and G' are calculated from the l'i J X

4 amounts of metal and of chelating compound known to be present in the solution. Is measured experimentally. Bjerrum discussed the statistical effects entering into successive complex formation. At first it might appear that the successive formation constants K^, etc., would be of equal size when the addition of a ligand to a metal ion does not change the ability of the metal ion to accept more ligands. This is not true and can be demonstrated by the following argument. Consider these consecutive steps:

m n-l + R # m n kn = Z \ 7 U)

MR „ + * * (b )

The tendency of step (a ) to go to the right is proportional to (N - n + l), the number of unoccupied positions of MR^ ^ . The tendency of step (b ) to go right is proportional to (N - n), the number of unoccupied positions of MR . ^ e tendency for step (a ) to go left is proportional to n, the number of ligand species R on MR . The tendency of step (B) to go left is proportional to (n + l), the number of ligand species on MR Also the tendencies are proportional to the concentrations of the species involved. At equilibrium the velocity to the right equals the velocity to the left.

r ^ n_±J U J (N - n + l) = f& /~MR^ 7n for (a).

Z M R j J Z \ 7 (N - n) = f^ / “m n+1_ 7 (n + l) for (b ). f and f, are factors introduced to allow for the fact that these a b tendencies are not always entirely determined by statistical considera tions . When only statistical effects are involved, f and f. are equal to one. & o

(n - n + l) (n + l)

(v i i ) V l (!1 - n) n

In the important case where N = 2 and n = 1, kx / k2 = 4. When effects other than statistical also enter, f and f, are not ’ a b likely to he equal. Bjerrum introduced a spreading factor, x.

kn (N - n + l) (n + l) x2 (VIII) kn+l (N - n) n

When x equals one, the separation of k and ^ is due to statis tical factors only. Values of x larger than one indicate the presence of other factors such as steric hindrance and charge effects. Values of x less than one are sometimes encountered and may indicate the tendencies of complexes to attain symmetrical configurations. It is important to notice that all of the above considerations apply also to polybasic acids. Here the central specie K becomes A, the least positively or the most negatively charged specie; and R becomes H, the proton. For a dibasic acid whose protons apparently dissociate simultaneously, pk and. pk „ are not expected to be equal. Q.-L If only statistical effects are operating, pk j will be 0.6 log units smaller than pk . For those acids having tivo closely situated carboxyl or phenolic groups, charge densities of the anions A- and HA become significant, and larger differences are to be expected. Wow considering equations (i) through (IV) for the cases which are important in this work, W = 1 and W = 2: Where N = 1, k^ // S . J 7 n = ------(V) 1 + kx /~R J

The data is usually plotted as n against pR, where pH = - log Z X 7 . Where n = -y, k £ ~ \ J = 1 and log k_ = pR-g- (IX) 1 2 1 _ In this case (N = l), the value taken from the graph at n = } needs no correction.

Where N = 2, 3^ £ b J + 2 / V / 72 K 2 n — (V) i + \ r * j + kxk2 z \ 7 2

This can he solved for k^ and for k^:

n k! = ------(X) F R _ 7 Z T i > n ) + (2-n)FR_7k2J

k (n - l) + ls^ (XI) Z“r 7 (2 - n)

Where n = equation (x) becomes

1 1 kl ~ =-=r— (XII) r * • 1 + 3k/\z

Where n = 1, 1 = k ^ / R 72 and log k^k = 2pRx (XIIl)

Equation (XIIl) is correct regardless of the size of x .

Where n = 3/2, equation (Xl) becomes

1 + (*„) *2 = x \ 7 3/2.

In the special case where Bjerrum's spreading factor, x, is large, and k^ is much larger than k2, equations (XIl) and (XIV) can be simplified. kn = 1 // n, i , and ---log k.. = pR 1 t y 1 ' T (XV)

k, = 1/ F l /3/o and log k, = PR3/„ (XVI) Then the values taken from the n - pR curve at n = -g" and|^give the correct values of k^ and k^. However, in the usual case the spreading factor, x, is not much larger than one, and the values of log k^ and log taken directly from the n - pR curve are, according to equations (XV) and (XVl), only approximately correct. A number of methods can be used to get the correct values of k^ and k^. First, k^ and k^ cam be solved by simultaneous equations for a number of sets of n - pR data. This method is laborious, especially when many data have to be calculated. Bryant, Femelius and Douglas (23) have found that such calculated values are in excellent agreement with those found by the convergence correction method to be described. Irving and Mrs. Rossotti (26) recommend a method of least squares. They point out that formulae similar to those used in Schwarzenbach's (15) graphical solution of acidity constants can be used. The 3lope of the n - pR curve at n = 1 has frequently been used to calculate log k^ and log k^, but errors arise in the plotting of the curve through the measured experimental points and in evaluating the slope. It is also apparent that the correct values of and can be obtained by a series of successive approximations using equations (XIl) and (XIV). Van Vitert, etal (27) had developed a graphical convergence correction method of using equations (XIl) and (XTV). This method is convenient, and its derivation is given below. Using this method, temporary values of log k^ = and log k^ = are taken from the n - pR curve at n = \ and 3 /2 respectively. The difference is a positive number, and the correction to be applied to and to to get correct values of log k^ and k^ is a function of this difference. Derivation of the convergence correction equation.

Rearrange equation (XIl) on page 7 and omit brackets from concentrations.

1- kxRf 3k1k 2Ri2 + - 1 = 0 (xlla) k kg = (Xllb) 3Ri2

kl (XIIc) Ii£ + 3k2R-2L2

Rearrange equation (XIY) on page 7. Omit brackets.

2 , n 3 + k. ^ * 2 ^ “ klR3/2 - 3 = 0 (XlVa) kxk2 = 1•V, ^ 2 (XlVb)

4 / 2

ki * (XIVc) vv2 - v2

Equate (Xllb) and (XlVb).

1 . k^ , 3 + k ^ Cross-multiply and solve for k^,

(IL, - 3R,) (8,/ - 3Ri) \ = 2 2 and k ^ = ^ 2 ^ (XVIl)

¥ V 2 V 2 10

Equate (XIIc) and (xlVc). 3 1 Cross multiply and solve for k^.

k2R3/2 " K 5/2 R Jr + 3k2R{ 2

1 ‘V 2 = ______and = ______(XVIII)

V 2 - 3Hi 2 < V 2 - 3EP

Define the temporary values taken directly from the graph as

C1 = pit= - log * log (XIX)

C2 = pR^y = - log I^y * log k2 (XX)

These temporary values, and C^, are too far apart, so by definitioni

Corr^ = - log k^ (XXl) and Corr2 = - C2 + log k2 (XXIl)

Take the log of (XVIl): log k^ + log Rj_ = log (R^,y - 3RL) - log R^y

'Use (xix) and (XX): log k^ - C^ = log ( ^ y - 3R.iJ + C2

Change signs and use (XXl). Corr = -C - log (R„ , - 3Ri) 1 2 3/2 2-

Use (XX) again: Corr^ = log R^y - log ( ^ y “ 3R_iJ j combine terms.

Cor^ = - log 3R-A (XXIII)

' V 2 '

Use (XIX) and (XX) log (R,/R^y ) = c2 " Cp and (R^/R^^ ) = antilog (^-C^)

Oorrj = - log Z"l - 3 antilog (c., - C±) J ( m v ) 11 Take the log of (XVIIl): log + log R^y = log R - log (R^y - 3Rj_)

Use (XIX) and (XXII); log = corr^ = log R^y - log - 3Rj_)

/ r5/“ 3Rj- \ Corr^ = ~ loa 2 j which is the same as (XXIIl), proving that

' %

the corrections are the same.

Table 1. Data for convergence correction graph. Equation (XXIV)

(Cf - C) Corr.

2.2 0.01 2.0 0.01 1.8 0.02 1.6 0.035 1.4 0.055 1.2 0.09 1.1 0.12 1.0 0.155 0.9 0.206 0.8 0.28 0.7 0.40 0.6 0.60 12

0.30

Corr.

0.20

0.10

OOO 0.8 IO 1.2 1.4 1.6 1.8 2.0 C | - C 2

FIGURE I. CONVERGENCE CORRECTION CURVE FROM TABLE I. l’he result of the derivation is equation (XXIY).

This equation is plotted on Figure 1 which is the same as the data published by Van Uitert etal (2 7). The correction obtained from the graph is subtracted from and added to C^. That is,

log - corr. (XXl)

log k2 = C2 + corr* (xxil)

The reason for naming these "convergence corrections" is that the correct values of log and log k^ are always closer together than the temporary values and C^. For equations (XV) and (XVI) to be correct, the complex formation steps must be well separated. The fact that this is true when (log k^ - log k2) is greater than two can be seen in Figure 1, which shows that the convergence correction is essentially zero above (c^-C^) values of two. All of M must go to MR before MR2 appears. As the complex formation steps become less separated, more and more MRg appears where MR^ is being formed as ~n goes from 0 to 1, and a correction is needed. The same type of thinking applies to dibasic acids. An n - pR curve is really no different than a pH-a curve, where a is equivalents of base added per mole of acid present. Accordingly, pH values at a = y and 3/g niay be convergence corrected to give pk&^ pk , In general, this method has been used for the dibasic r &2 values. D ’ acids in this work. In several instances, values of k^ and k2 were also calculated by simultaneous equations and Schwarzenbach* s graphical method derived below. In all cases tried, the agreement among the three calculations was satisfactory. It is important to note that these values of pka^ and pka^ may differ considerably from the temporary values taken directly from pH-a curves. This convergence problem does not arise with monobasic acids, or for the constants of

1 pH = -log £ e +J in all that follows. polybasic acids where the dissociation steps are well separated. Examples of the latter are the third proton of anthranilic acid diacetic acid and the dissociation of 2-(aminomethyl)-benzoic acid. Scliwarzenbach.1 s 1-method, for the Graphical Determination of Acidity

Constants (15).

The original solutions contained the dibasic organic acid H^R and nitric acid. These solutions were titirated with sodium hydroxide.

H2 R = HR" + H+ ka = Z"H+_7 (XXV)

m~ = r- + H+ k - pd+J DrJ/r^y Uxvi) 2 Balance of charges requires: £ e+J + r J-a+_7 = r 3H~_7 + /Tm ~J + 2fsrJ + (xxvii)

Conservation of the organic acid requires:

C R = jH el R_7 + Z H C 7 + Z~R=_7 (XXVIII) 2 2 Substitution from equations (XXV) and (XXVIIl) for solving (XXVIII) for D t J yields: k k C _ _ _ al a2 2 Z~R J = ------(xxix)

Z"H+_72+ k /~H+_ 7 + k k al al a2

Substitution from equation (XXVl) and rearranging (XXVII) yields:

Z"h+_7 + /Na+_7 - lf0R“-7 - / j ^ 1 7 = Z“r=_7 (2 + Z"r+_7/ r ) (XXX) 2 j’or convenience let

Z~H+_7 + Z~Na+_7 - Z~0H"_7 - L ^ J = b (XXXI)

Solve equation (XXX) for R"_7, and equate to ]_ R~_7 from equation (XXIX).

h °HoR ZX7 = b 1 2 2 ka + L H+_/ L H+_/ + k / h V + k k (XXXII) 2 al al 2

15 Cross-multiply equation (XXXIl):

b ^ J 2 + bk /~H+_7 + k k b = 2 k k C ^ + k CU D £ k +_ J al al a2 al a2 2 al 2

b Z~H+J7 = k k (2C - b) + k (C jT k +J - b/“H+J ) al 2 2 1 2

Divide by k : ai

- % {2°H2B ' b) + Z_H+-7 V - b)

Which rearranges to

l A aj = + < 2 0 ^ - * ) ^ - ( b - C ^ ) (XXXIII)

b r n j 2 b-

Equation (XXXIII) is the equation of a straight line of the form (y = mx + b) with x = k and y = l/k . This straight line a2 al intersects the x axis at (b - C R) f H *J (XXXIV) 2 A =' 2 C„ R - b 2

and intersects the y axis at -- R (XaXV) B = - b # VJ

Each point during the titration of the dibasic acid has a different concentration of hydrogen ions, ~ J , and a different calculated value of b. The result is that a different straight line is obtained for each addition of base. These many straight lines should have a common intersection for which x = k , and for which y = l/k . Such data have been plotted a2 al 17 for N,W' trimethylene dianthranilic acid in Figure 2, from Table 2.

Table 2. Schwarzenbach method data for N,N* trimethylene

dianthranilic acid. Also found in Table 54.

Ml. bases a pH corr. A B

3.400 1.406 6.19 -23.8 X IQ"8 +2.17 X i o 4*6 3.770 1.570 6.38 -12.3 X 10"8 +1.72 X i o 4-6 4.010 1.675 6.47 -8.07 X 10-8 +1.34 X 10+6 4.270 1.789 6.54 -4.80 X 10"8 +0.87 X 10+6 4.520 1.900 6.73 -1.54 X 10"8 +0.53 X 10+6 4.830 2.035 6.88 +0.59 X 10-8 -0.29 X 10+6 5.170 2.185 7.02 +2.33 X 10"8 -1.72 X 10+6 5.510 2.335 7.14 +3.81 X 10”8 -3.54 X 10+6 5.810 2.465 ,7.28 +4.81 X 10"8 -6.16 X 10+6 6.120 2.603 7.44 +5.76 X 10"8 -10.44 X 1048 6.500 2.77 7.74 +6.24 X 10"8 -24.0 X 10+6 6.800 2.90 8.16 +6.80 X 10"8 -68.7 X 10+6

From Figure 2 pK = 6.45 + 0.07 and pK = 7.17 1 0.04 al a2 '

e> £: Calvin - Bjerrum pH titration equations.

A majority of ligands R are the anions of weak acids. These acids may be mono- or polybasic. Calvin and Wilson (2l) introduced a modifica tion of the Bjerrum pH titration method in 1945. First the acid is titrated with standard base in the absence of cations with which the ligand might form complexes. From this data the several pk values of the acid are obtained. Using these pk 's. the a a relative concentrations of the ligand specie and the several protonated species may be calculated for any solution for which the pH is measured. In considering the Bjerrum method previously described, it can be seen that the determination of the concentration of ligand, A7. could often be the major problem. When R is the anion (or non-protonated specie) of a weak acid, can easily be calculated from the measured pH, and the problem is much simplified. Next the acid is titrated with standard base in the presence of the cation whose complex formation constants are to be found. Now the pH-a curve of the acid comes across at lower pH values. Examples of this are seen in Figures 17 and 26. The following type reaction is the reason for these lower pH values. K + HR = HR + n H+ n All of the concentrations needed to calculate the complex formation constants can be obtained from the following information:

(1) Cjyj, the total of all metal-containing species. (2 ) C^, the total of all ligand-containing species. (3 ) The experimentally measured pH. (4) The several dissociation constants of the acid. (5) A, the excess strong acid added for the purpose of getting data at low pH values where the degree of complex formation is small. (6) The total volume, for the purpose of correcting concentrations for the dilution occuring during the titration.

19 20 (7) The volume of standard base added.

Four separate cases are encountered in the present work.

(a) Weak monobasic acid. (c) Weak tribasic acid. (b) Weak dibasic acid. (d) Tribasic acid having one strongly dissociated proton. Derivation of Equations

Case (a). Weak monobasic acid

The solution initially contains nitric acid, the weak acid HR, and metal nitrate. The solution is titrated with standard sodium hydroxide.

HR * R + H+ \-r*JL*J/ruO (XXXVI)

M + R A MR k2 = M / M M (l)

m r + r * m r 2 k2 = / ~ r _ 7 (i i )

CM = £kj + /~mr_7 + Z " i ® 2 - 7 (xxxvii )

CR = Z”MR_7 + 2/MR^y + Z\ 7 + (XXXVIII)

Conservation of protons leads to equation (XXXIX)

CR + foiTj + A - Z~Na+_ 7 = Z"H+_7 + Z “HR_7 (XXXIX)

That is, protons came from the weak acid HR, from the dissociation of water, and from the excess of strong acid A added. Protons were removed by the addition of the standard base; this is the reason for the negative sign before the ]_ Ha^ 7 term. During the titration protons are found only in two species, H+ and HR. Rearranging (XXXIX) and eliminating by the use of equation (XXXVl); Z \ 7 = 0R + / - 0 H - J 7 + A - - C*J (XL)

r f j t xa Z “HR_7 = CR + Z ”o h “_ 7 + A - /"l'Ja+_7 - Z~H+_7 (XLl)

21 Then rearranging equation (XXXVIIl):

£ m J + 2/ ~ m r 2J 7' = cR - / " r _ 7 - Z “h r _ 7 (xlii)

Using the definition of n according to equation (iv) on page 4» equation (XXXVII), and equation (XLIl): CR - /V 7 - f m J (XLIIl)

In terms of directly known or measured quantities equation (XLIIl), by substitution from equations (XL) and (XLl), becomes

Z ”h+_7 cr - (ka + Z"h+_7)(cr + £ ~ o e _J + a - - Z \ 7 ) a _

Z h +_ 7 cm (x l i v )

The various methods of getting log k^ and log k^ from n - pR data have been discussed. Case (b). Weak dibasic acid

The solution initially contains nitric acid, the weak acid H^R, and metal nitrate. The solution is titrated with standard sodium hydroxide.

H2R = HR + H+ (xxv) k = Z" h 7 Z hrJ 7 Z V - 7 1 ^

HR # R + H+ ka (xxvi) 2

h + R MR kx = D ^ J / D Q r ^ J (i)

MR H- R ?= KR^ k2 = r ^ / D * j r * j (ii)

cH = Z X 7 + / m k 7 + r ^ j (x x x v i i )

cR = £ m j + 2£ v i r 2J + Z \ 7 + r m j + Z h 2h_7 (xcv) 23 Conservation of protons leads to equation (XCVI)

2 CR + + A - D ? J + 3 k 7 + 2^ 2 R_ 7 (XCVl)

That is, protons came from the dissociation of water, from the excess of strong acid A added, and two from each molecule of HRR. Protons were removed by the addition of the standard base; this is the reason for the negative sign before the ^~Naterm. During the titration protons are + found only in three species, H , HR, and HRR. Rearranging equation (XCVl), and eliminating and by the use of equations (XXV) and (XXVl),

- _ 2C + / “OH",/ + A - Z"Na+J7 - Z"H+_7 / r_7 = Hr rza------t------(xcvii) ^ ■ _ 7 2A a ^ + X h _7/ka a l 2 2

/hr_7 = 2Cr + ^-~QH J * k ~ -^~Na -7 ~ Z~H -7 (xcvni)

2 / k +1 al

Z~H+_y (2Cr + Z~OH" J - A - Z~Xa+_7 - Z~H+_7 ) (XCIX)

2 Z~ H V + k, al

Then rearranging equation (XCV):

C kR_7 + 2 = cR - Z~r_7 - Zhr_7 - Z"h2r.7 (c)

Using the definition of n according to equation (IV) on page 4, equation (c) and (X-LXVIl):

cH - Z\ 7 - _ Z“h2r_7 - = (CI) In terms of directly known or measured quantities equation (Cl), by substitution from equations (XCVIl), (XCVIIl), and (XCIX), becomes:

k k a2 al UFJ + ka ) oE- (----- + k + Za+_7)(2cR + /pu~J + 1 Z"H+j 1 n =

(2 /H+_7 + CM

.. .a - Z X 7 - Z~h +_7) (Oil)

The various methods of getting log k^ and log k^ from n - pR data have been discussed.

Case (c). Weak tribasic acid

The solution initially contains nitric acid, the weak acid H^R, and metal nitrate. The solution is titrated with standard sodium hydroxide.

h^r = h2r + h+ k = r^J3^j/r^j ( c m )

H2R £ HR + H+ k = (CIV)

HR £ R + H+ k = Z“h_7 n ^ 3 I B & J (cv) a3

h + r # mr k1 = r m j / r o r r_z (i)

i-iR + r * mr2 k2 = z~^ / r ^ j z \ 7 (i i )

CK = /\ 7 + Z~mr_7 + ( x x x v i i )

cR = f m j + 2Z"iir^7 + Z\ 7 + Zhr_7 + Z\r_7 + Z X r 7 (cvi) 25 Conservation of protons leads to equation (CVIl).

3Cr + f w j * A - Z"Ka*J = / H+J + £ m j +

(CVIl) That is, protons came from the dissociation of water, from the excess of strong acid A added, and three from each molecule of H^A. Protons were removed by the addition of standard base; this is the reason for the negative sign before the Z V J tern. During the titration, protons are found only in the species, K , HR, H^R, and H^R. Rearranging equation (CVIl), and eliminating j/~HR_/, Z ~ t and H^R^T" by the use, of eqxiations (CIIl), (CIV), and (CV),

(3Cr + Z"0H'_7 + A - Z “Na+_7 - £~ll+J ) H_y = ------(cvin)

3A 7 3 + 2/-IIJ 2 k + y-Hj q k, al al "2

\ ka2 (3Cr + y o H - J + A - / V A - C m J = ------(cix)

jA hJ 2 + 2 A 7 * 4~ lc 1c al a l a 2

r * J k (3C + Z X 7 + A - Z"Na+_7 - Zh2r7 = :------(cx) ^>M2 + 2Z~h_7 k + k k 1 al 2

Z X T (3Cr + T ohJ 7 + A - Z"Na+J - Z V - J ) (CXI) ^ * 7 =

3 Z h_7 2 + 2 A 7 k + k k 1 1 2 26 Then rearranging equation (CVl)

Z m r _ 7 + 2/lffi2_7 = CR - £ rJ - f m j - Z " h 2r _ 7 - (cxn)

Using the definition of n according to equation (IV) on page 4, equations (CXIl) and (XXXVIl):

-- - cR - /"r_7 - Z"hr_7 - Z"h2r_7 - (cxiii)

n = C

In terms of directly known or measured quantities equation (CXIIl), by substitution from equations (CVIII), (CIX), (CX), and (CXl), becomes

:: - CR - ( ■■■ ^ / - ■ - + V * 2 + 3 J \ + ...... J 1 2 1

n = ( CXIV ) Si 3Cr + jT o a J J + A - T N a _ 7 - Z " h +_ 7 . . ( _J:______)

5/l-i_72 + 2 / \ 7 k + k k a l al a 2

The various methods of getting log k^ and log k2 from n - pR data have been discussed.

Case (d). Tribasic acid having one strongly dissociated proton

This case is somewhat different than case (c). The species Hyl has zero concentration. No strong acid needs to be added; therefore the term A is absent from the equations. The solution contains the tribasic acid and metal nitrate; it is titrated with standard sodium hydroxide. H R £ HR + H* k = D&J Z”HR_7/Z"H0R_7 (CIV) <£ ^

HR * R + H+, k = / X 7 / rJ 7 Z “ hr_ 7 (c v )

cM = d j + d &j + d ^ j {xxxvii)

cR = £ m j + 2/"mr2_7 + £ rJ + Z~RR_7 + Z~H2R-7 (x°v)

Conservation of protons leads to equation (CXV).

3cr + Z"oh'_7 - Z"Ra+_7 = Z~h+_7 + Z"hr_7 + 2Z“h2r_7 (CXV)

That is each tribasic acid molecule yields three protons and each water molecule which dissociates yields one proton. Protons were removed by the addition of standard base; this is the reason for the negative sign before the ] term. During the titration, protons are found only in the species H , HR, and H^R. Rearranging equation (CXV), and eliminating J_ HR_J and J_ H^R_] by the use of equations (civ) and (CV),

Z " r _ 7 = k k (3Cr + - Z~h+_ 7 ) (cm) 3. *7 £ w fouTj - 2 p

^ t 2 + r * +j \ 2

D bs J = k (3Cr + Z “oh " _ 7 - Z > a +_ 7 - Z ~ H +_7) (CXVIl)

2 Z “k _7 + k 2 28

r*j (3cr + z “oh_7 - z v . 7 - d ?j ) f E ^ J = (CXVIII) 2/H4J + k 2

Then rearranging equation (XCV)

Z X 7 + 2/m r^ = ca - Z“r7 - Z“hr_7 - Z”h2r7 (c)

Using the definition of n according to equation (IV) on page 4 } equations (c) and (XXXVIl):

CR - ZX7 - Zhr_7 - Z"h2r_7 (c i)

In terms of directly known or measured quantities equation (Cl), by substitution from equations (CXVl), (CXVIl), and (CXVIII), becomes

The various methods of getting log k^ and log k^ from n - pR data have been discussed. Case (a) includes anthranilic acid, N-methyl anthranilic acid, and salicylic acid. Case (c) includes only anthranilic acid diacetic acid. Case (d) includes only N-(aminoethy1)-anthranilie acid dihydrochloride. All of the remaining acids are dibasic and are covered by case (b). EXPERIMENTAL

The Compounds

In the present work thirteen organic acids are involved. For purposes of reference and comparison, their names and formulae will now be written. Each is preceded by a compound number. Occasionally, for convenience, the number of the compound rather than its full name will be used,

(i) Anthranilic acid

^,-COOH (il) N-methyl anthranilic acid

^-COOH KOOC (ill) 2,2' imino dibenzoic acid E

(IV) 2,2' hydrazo dibenzoic acid

(V) Methylene dianthranilic acid

^s-CQOH (Vi) N,W Ethylene dianthranilic acid -CH -NH-

(VIl) N,N' trimethylene dianthranilic 'V.-C00H H00C-

acid o ^ -lffl-CH -CH -CH -NH- 30 (VIIl) N-(aminoethyl)-anthranilic -COOH acid -NH-CH2-CH2-NH2

-COOH (ix) 2-(aminomethyl)-benzoic acid -c h 2-n h 2

-COOH (X) Salicylic acid -OH

-COOH (Xl) o-(carboxymethoxy)—benzoic acid -0-CH2-C00H

-C0QH (XIl) N-(carboxymethyl)-anthranilic acid O-NH-CE2-C00H

-COOH (XIIl) Anthranilic acid diacetic acid ,CH COOH -N, ■CH COOH

Preparations of the Compounds

The methods of preparation of the compounds will be briefly discussed and illustrated by means of equations. The detailed experimental procedures have been placed in the Appendix.

(i) Anthranilic acid. This compound was obtained from the Coleman and Bell Chemical Company and was prepared for use by recrystallizing from water. It melted at 144°C. (II) N-methyl anthranilic acid. This compound was a white label reagent of the Eastman Kodak Company. It was prepared for use by dissolving in dilute sodium hydroxide, filtering the basic solution, and reprecipitating the compound by acidification with dilute hydro chloric acid. It melted at 182°C. 32 (Ill) 2,2' imino dibenzoic acid. The directions of Ullman and Hoz (28) were followed in the preparation of this compound. These directions are similar to those given later by Purgotti (2 9), Drozdov and Bekhli (30), and Villemey (3l). All of these give 294 to 297°C. as the melting point range, and this is the value obtained in the present work.

COOH HOOCV COOH Cl // S \ _ _ 4 n h (Cu)

(IV) 2,2' hydrazo dibenzoic acid. The preparation of this compound closely followed the directions given by Sargent and Pedlow(32), Other directions for the reduction of o-nitro benzoic acid had previously been given by Loewenherz (33), lob (34), and Moir (35)*

>— COOH NaOH V i W ZnO + Al ( CdSO,

Heating with aqueous hydrochloric acid causes this compound to rearrange (32,33).

-COOH HC1 Mi. <■ \ // )2 A

(V) Methylene dianthranilic acid. The directions of Bischoff and Reinfeld (3 6) were followed in the preparation of this compound.

-COOH 0 ^rv-COOH aO + 1 H-C-H CO“iCH. (Vi) N,H' ethylene dianthranilic acid. Harris (l) prepared this compound starting with ethylene dibromide and methyl anthrani- late. Hydrolysis of the resulting ester gives the dianthranilic acid. Details of the preparation are given in his dissertation (l). ,-COOCH /^-COOCIL CV h H 2 + Br-(CH2)2-Br ______) ( { VlJH-CH^ ^

(VII) WjN' trimethylene dianthranilic acid. The directions of van Alphen (3 7) were followed in the preparation of this compound, and the melting point of 209°C. was confirmed.

-COOH _r-COOH a -1H2 + Br-(CH2)3-Br > ( ^

(VIII) N-(aminoethyl)-anthranilic acid. The method used in this work was the reaction of o-chloro benzoic acid with an excess of ethylene diamine.

l-COOH / - = y C00H / 3 " C1 + H2H - ™ 2-CH2-ilH2 > - 2— 2— 2

This compound was prepared by Bachman and tfelton (38) by a method considerably different than that reported here. Their synthesis was

^t-COOH------U300H CV n h 2 + c i - c h 2- c h 2-n o 2 ______^ / \Viih-ch 2- c h 2-n o 2 The intermediate nitro compound was reduced with hydrogen and Raney nickel.

(IX) 2-(aminomethyl)-benzoic acid. The preparation of this compound involved a number of steps. Directions for each step were adapted from "Organic Synthesis". The melting point of 217-8°C. agrees with that reported by Wegscheider (39).

(x) Salicylic acid. This compound was obtained from Merck and Company. It was recrystallized from water before use.

(XI) o-(carboxymetkoxy)-benzoic acid. The directions of Meyer and Duczmal (4 0) were followed in the preparation of this compound, and the melting point of 191-192.5°C. agrees well with their value. r=r>-COOH /T=n-COOH + C1-CH2-C0QH KaQH ' / Yo-Ct^-COOH

(XII) N-(carboxymethyl)-anthranilic acid. This compound was prepared by the reaction of excess anthranilic acid with chloro acetic acid. It has been prepared frequently (4 1, 42, 43, 44).

-vCOOH /^-COOH rYmh2 + ci-ch2-cooh Na0H ^ Ym-CH2-C00H (xill) Anthranilic acid aiacetic acid. The preparation of this compound was similar to the previous one; however, an excess of chloro acetic acid was used. The melting point of 210-212°C. agrees with the value of 212° given by Vorlander and Mumme (45).

I \-NH_ + 2 C1-CH„-COOH Wa0H . v // 2 2 7 'ch cooh

Elementary analysis for the nine compounds prepared for the present work is given in Table 3. The calculated and measured equivalent weights of all thirteen compounds are given in Table 4 . Infrared spectra of eacn of the thirteen compounds were deter mined and are shown in Figures 3 through 15♦ The samples were mulled in Nujol. A Perkin Elmer Model 21 double-beam instrument was used. 36

Table 3. Elementary analysis of nine prepared compounds.*

Carbon Hydrogen Nitrogen Number Name Calc. Found Calc. Found Calc. Found

2,2' imino . , 65.40 65.46 (III) aibenzoic acid 4.31 4.43 5.45 5-35 65.60 4.55 5.54

(IV) 2,2' hydrazo 61.70 61.85 4.44 4.41 10.30 9.13 dibenzoic acid 61.85 4.54 10.25

(V) Methylene 62.90 62.78 4.93 5.03 9.80 9.61 dianthranilic acid 62.94 5.18 9.67

(VII) N,N‘ trimethylene 64.95 64.68 5.77 5.66 8.91 8.78 dianthranilic acid 64.75 5.80 8.82

(VIII) N-(aminoethyl)- 43.00 42.83 5.57 5.52 11.07 11.12 anthranilic acid 4 2 .8 8 5.65 11.18 dihydrochloride

(IK) 2-(aminomethyl)- 51.20 51.10 5.35 5.53 7.46 7.27 benzoic acid 51.27 5.33 7.36 Hydrochloride

(XI) o-(carboxymethoxy) 55.05 54.92 4.11 4.14 0 - benzoic acid 55.11 4.19

(XII) N-(carboxymethy1) 55.40 55.25 4.65 4.59 7.17 7.14 anthranilic acid 55.39 4.74 7.15

(XIII) Anthranilic acid 52.10 51.86 4.37 4.44 5.53 5-42 diacetic acid 51.87 4.55 5.55

* The analyses were performed by the Galbraith Microanaly- tical Laboratories, Knoxville, Tennessee. Table 4. Equivalent weights of the compounds.

Number ITame E. W. Found E. W. Calculated

(I) Anthranilic acid 136.3 137.1 (II) N-methyl anthranilic acid 151.5 151.2 (III) 2,2' Imino dibenzoic acid 128.4 128.6 (IV) 2,2' Hydrazo dibenzoic acid 136.1 136.1 (V) Methylene dianthranilic acid 144.0 143.2 (VI) N,N'Ethylene 150.4 150.1 (VII) N,N1 Trime thylene dianthranilic acid 157.4 157.15 (VIII) N-(Aminoethyl)-anthranilic acid dihydrochloride 84.5 84.4 (IX) 2-(Aminomethyl)-benzoic acid hydrochloride 94.25 93.85 (X) Salicylic acid 138.3 138.1 (XI) o-(carboxymethoxy)- benzoic acid 98.1 98.1 (XII) N-(Carboxymethy1)- anthranilic acid 97.6 97.6

(x i i i ) Anthranilic acid diacetic acid 84.4 84.4 TRANSM ISSION 100 20 80 0 6 00 4000 5000 ------1— 3000 IUE . NF D SETU O ATRNLC ACID ANTHRANILIC OF SPECTRUM ED R A FR IN 3. FIGURE 2000 1500 AE UBR, CM"' NUMBERS, WAVE S N O R C I M , H T G N E L E V A W 00900 1000 0 0 8 00 70 % TRANSMISSION Iwv 0 8 0 4 0 6 00 50 00 00 700 0 80 0 0 9 1000 1500 0 0 0 2 0 0 0 3 0 0 0 4 5000 IUE . NRRD PCRM F - TY ATRNLC ACID ANTHRANILIC ETHYL N-M OF SPECTRUM INFRARED 4. FIGURE -1 . M C , S R E B M U N E V A W h t g n e l e v a w , s n o r c i m vO WAVE NUMBERS, CM."1 2000 1500 1000 9 0 0 80 0 ->—rA------f------i------

1 i 6 8 10 12 WAVELENGTH, MICRONS

FIGURE 5. INFRARED SPECTRUM OF 2,2' IMINO DIBENZOIC ACID WAVE NUMBERS, C M '1

5000 4000 3000 2000 10001500 900 800 700 100 1—

*- 4 0

WAVELENGTH, MICRONS

FIGURE 6. INFRARED SPECTRUM OF 2,2' HYDRAZO DIBENZOIC ACID

■p- v-1 % TRANSMISSION 0 4 0 8 60 20 00 00 00 00 50 00 0 80 700 800 900 1000 1500 2000 3000 4000 5000 IUE . NRRD PCRM F EHLN DATRNLC ACID DIANTHRANILIC METHYLENE OF SPECTRUM INFRARED 7. FIGURE AE UBR, CM.-1 NUMBERS, WAVE S N O R C I M , H T G N E L E V A W p- -p ro WAVE NUMBERS, CM.-1

5000 4000 3000 2006 1500 1000 900 800 700 100 I---- 1—

WAVELENGTH, MICRONS

FIGURE 8. INFRARED SPECTRUM OF N.N1 ETHYLENE DIANTHRANILIC ACID % % TRANSMISSION 100 20 0 6 40 0 8 00 00 00 00 50 00 0 80 700 800 900 1000 1500 2000 3000 4000 5000 IUE . NRRD PCRM F .1 RMTYEE DIANTHRANILIC TRIMETHYLENE N.N1 OF SPECTRUM INFRARED 9. FIGURE ACID AE UBR, CM.-1 NUMBERS, WAVE S N O R C I M , H T G N E L E V A W * % % TRANSMISSION 100 20 80 60 0 4 00 4000 5000 ------IUE 0 IFAE SETU O N(MNEHL- ANTHRANILIC N-(AMINOETHYL)- OF SPECTRUM INFRARED 10. FIGURE 2000 CD DIHYDROCHLORIDE ACID 501000 1500 AE UBR, CM"1 NUMBERS, WAVE S N O R C I M , H T G N E L E V A W 0 0 9 0 0 6 700 % TRANSMISSION 100 0 4 20 80 60 00 00 3000 4000 5000 IUE I IFAE SETU O 2"AMI - C ACID IC O Z N E )-B L Y H T E M 0 IN M "(A 2 OF SPECTRUM INFRARED II. FIGURE 2000 HYDROCHLORIDE 1500 S N O R C I M , H T G N E L E V A W 1 ' . M C , S R E B M U N E V A W 1000 900 0 700 800

% % TRANSMISSION ool o to 0 4 20 60 80 00 0 0 0 4 5000 ------1— 001500 3000 IUE 2 IFAE SETU O SLCLC ACID SALICYLIC OF SPECTRUM INFRARED 12. FIGURE 2000 AE UBR, CM."1 NUMBERS, WAVE S N O R C I M , H T G N E L E V A W 1000 900 800 700 WAVE NUMBERS, CM.’ 1 5000 4 0 0 0 3000 1500 1000 900 6002000 7p 0 1001--- 1—

6 0

4 0

WAVELENGTH, MICRONS FIGURE 13. INFRARED SPECTRUM OF 0 - (CARBOXYMETHOXY)-BENZOIC ACID WAVE NUMBERS* C M . ' 1

5000 4000 3000 2000 1500 1000 900 800 700 IC_

4 0

WAVELENGTH, MICRONS

FIGURE 14. INFRARED SPECTRUM OF N-(CARBOXYMETHYL)-ANTHRANILIC ACID WAVE NUMBERS, CM.-1

5 0 0 0 4 0 0 0 3000 2000 1500 1000 900 80 0 1001-- -j— 700

6 0

• - 4 0

i0 i i i 2 4 6 8 10 i WAVELENGTH, MICRONS

FIGURE 15. INFRARED SPECTRUM OF ANTHRANILIC ACID DIACETIC ACID 51 All thirteen compounds contain ortho-substituted, benzene rings and have absorption bands indicative of this structure. These are near 1600, 1170, 760, and 710 cm. All thirteen compounds have a broad band in the range 2800 to 2400 cm. ^ and a strong band at 1250 cm.”'*'. The first is related to OH stretching vibrations, the second to CO stretching vibrations or OH deformation vibrations. Another carboxyl frequency should appear in the range 1400 to 1440 cm.-\ but nearby bands due to Nujol generally inter fere. Another carboxyl group band, in the range of 960 to 900 cm. \ appears for all compounds except N,N' ethylene dianthranilic acid. Only three compounds, o-(carboxymethoxy)-benzoic acid (Xl), N-(carboxymethyl)- anthranilic acid (XIl), and anthranilic acid diacetic acid (XIIl), have aliphatic carboxyl groups: these have a band at 1750 cm. "*■. All of the compounds have a carboxyl group on the benzene ring, and all except anthranilic acid diacetic acid have a peak near 1670cm.The absence of the peak for this compound supports Schwarzenbach's (16) conclusion that this compound exists as a zwitter ion, with one proton attached to the nitrogen. The strong absorption of this compound at 1590 cm.""'*" and the broad band at 1560 cm. can both be assigned to the ionized carboxyl group. Each compound containing a secondary amine group lias a sharp peak near 1540 cm. Each compound containing a secondary amine group, which is not protonated, has a sharp peak near 5400 cm.-'*'. Anthranilic acid has two bands here. Absorption in the range 1560 to 1280 cm. "*■ varies widely, and assignments have not been made. The Solvent Medium

Because the organic acids and metal chelate compounds investi gated in this work are not in general soluble in water, it was necessary to use another solvent medium, Harris (l) investigated the possibilities of using a. number of organic solvents, and decided that dioxune-water mixtures are most satisfactory. Dioxane is an excellent solvent for a wide variety of organic compounds, and once these compounds have been dissolved in dioxane, the addition of water causes no difficulties. Among the compounds used in this work only 2-(aminomethyl)-benzoic acid hydrochloride and N-(aminoethyl)-anthranilic acid dihydrochloride were quite insoluble in pure dioxane, but they were quite soluble in water and in the 50$ dioxane-water mixture. In this work and in Harris's, the solvent medium was 50 volume $ dioxane. The solutions titrated initially contained 50 ml. of pure dioxane and 50 ml. of water and aqueous solutions. It is important to note that there is a volume contraction; the total volume is 98.7 ml., not 100.0 ml. This contrac tion is mentioned by Irving and Mrs. Rossotti (46), but not by many other authors. Failure to allow for this contraction causes an error in the values of all calculated concentrations except hydrogen ion. This error is not as important as it first might appear because it occurs in both the numerator and the denominator of the quotient n. The errors in terns used in calculating J_ R_7 tend to cancel. It is much more important to allow for the concentration changes resulting from the increase in total volume as the base is added during the titrations. Commercial dioxane is not pure because considerable amounts of acetaldehyde are formed during its synthesis and peroxides form during its storage. The method of purification used was similar to that used by Calvin and Wilson (2l). Two liters of commercial dioxane manufactured by the Carbide and Carbon Chemical Corporation and 200 ml. of 1 N HC1 were refluxed in a three-liter flask overnight. After cooling, the solution was agitated with a portion of K0H pellets. This removed both HCl and water as an orange liquid at the bottom of the flask. The dioxane was removed by decantation, and then treated with a second portion of KOH. Two portions were usually sufficient, as indicated hy the fact that not all of the pellets of the last portion dissolved. Next the dioxane was refluxed overnight with metallic sodium cut to the size of large peas. Sufficient sodium was used so that shiny metallic spheres were present at the end. Finally the dioxane was distilled through a fractionating column about three feet long. About fifty ml. of liquid coming over first and having a low boiling range was discarded. The remaining main portion distilled at 101-102°C., and was collected. This purified dioxane was stored in the dark and protected from exposure to the air as much as was practical. It was usually used within two week's time. Experimental titration procedures.

A. Determinations of acidity constants and equivalent weights. Approximately 0.01 equivalents of the solid acid was accurately weighed into a 250 ml. bealcer. Fifty ml. of dioxane were added, and the solid acid was dissolved except in those cases where it was a hydrochloride. Next 5.00 ml. of 0.10 N nitric acid were pipetted in. Finally enough distilled water was added to make the total of the aqueous portions 50 ml. The beaker was placed in the water bath and covered with a watch glass during the time required for its contents to come up to 35°C. The pH meter was standardized at 4.02 at 35°C. with a Beckman Mo. 14044 buffer. The cover glass was removed; the electrodes, stirrer, and burets were lowered into the beaker; and the titration was started. The stirrer was stopped when the pH meter was read. In those cases noted in the tables, equal volumes of dioxane and 0.2 N NaOH were added. In other cases only 0.2 If IfaOH was added. The volumes of base added and the pH meter readings were recorded. In most cases, the standardization of the meter was checked after the titration was completed. Any color changes or precipitates were noted. B. Determinations of formation constants. The same experimental procedure was used with one addition. A pipetted portion of 0.01 Id metal nitrate solution was included in the total aqueous portion of 50 ml. It was added after the nitric acid. The 0.2 N IfaOH and 0.1 N HNO^ were standardized reagents and were supplied by the Ohio State University Supply Stores. The 0.01 M metal nitrate solutions were prepared from analytical grade reagents and standardized by titrations with standard versene. Calibration of the pH meter for 50 volume % dioxane. In the Calvin-Bjerrum method used in these studies it is necessary to calculate the concentration of hydrogen ions from the reading obtained on the pH meter. If the reading- does correspond to the concentration of hydrogen ions present in a known solution, 55 ' then no calibration is necessary. Even in solutions having water alone as the solvent an exact correspondence between the observed pH meter reading and the calculated hydrogen ion concentration is not observed or expected. The reason for this is that the pH meter is usually standardized with some buffer solution, and the reading at which it is standardized has been established in terms of hydrogen ion activity. Very often in the use of water-organic solvent media considerable liquid junction potentials arise in the glass electrode - calomel cell system, and the meter readings are considerably different from the pH values calculated from the concentrations of hydrogen ions believed present. A correction for the pH meter must be made. This is either added to or subtracted from the meter readings so that the corrected meter readings correspond to the actual stoichiometric concentrations. In sin earlier paper Bryant, etal (2 3 ) stated that a correction was not used for the medium 50 volume ft dioxane. In this paper it was stated that the pH meter readings had been shown to be accurate to + 0.05 units and this was considered to be only very little more than the error involved in reading the pH meter. Calvin and Wilson (2l) also stated that the behavior of the glass electrode-calomel cell in 50^ dioxane was so close to that in pure water that no pH correction was needed. No correction was used in Harris's work, and indeed, the pH values he recorded at the beginnings of his titrations indicate that no correction should have been used. Apparently the behavior of individual cells varies slightly, and some may require a larger correction than others. Later van Uitert etal (47, 48) investigated several dioxane- water media mixtures and found that calibration and corrections become more important as the fraction of dioxane increases. They give the results of complete studies of the variation of the correction as a function of fraction of dioxane and also the concentration of electrolytes present. Their treatment includes considerations of activities and allows the calculation of thermodynamic acidity 56 constants in terms of activities. The constants obtained are for mono-basic acids and involve the use of activity coefficients determined for hydrochloric acid in the same medium for the corresponding ions of the weak acids. The extension of such treatment to polybasic acids would be difficult. In all cases in the present work, the meter and the electrodes were standardized at a meter reading of 4.02 at 35°C. using Beckman pH 4 buffer Ho. 14044. In this discussion, and in all that follows, pH is defined as pH = - log Z~H+_Z. With the first set of electrodes used in the present work, it was found that the pH meter readings obtained during the titration of nitric acid with 0.2 N NaOH in 50 volume ft dioxane were 0.10 units lower than the pH values calculated from the concentrations of ions present. A second set of electrodes that was used required a correction of 0.07 units rather than 0.10 units. That is, the meter readings were 0.07 units lower than the pH values calculated from the stoichiometric hydrogen ion concentrations. The corrections are positive in both cases. pH = Meter reading + Correction, corr.

A rather important assumption enters here. It is assumed that the nitric acid is completely dissociated. Such an assumption is probably not correct, especially in view of the fact that the dielectric constant of 50 volume ft dioxane is considerably lower than that of water. In the calibration, the calculated concentration is the stoichiometric concentration. The actual concentration is probably somewhat less because of ion association and incomplete dissociation. When the corrected pH values are used in the calculations with titrations of weak acids, the hydrogen ion concentrations calculated are not the actual concentrations, but correspond to the concentrations which would exist if the same solute were in water instead of 50 volume °ft dioxane. For 50 volume ft dioxane Charles and Freiser (49) list corrections of 0.07 and 0.14 pH units at 25 and 40°C. respectively. Holmes and Crimmin (50) list 0.07 as the correction they used. As a part of their calibration experiments van Uitert and Haas (4 7) did titrations in which both the glass electrode-calomel system and the hydrogen electrode-calomel system were present. They found that the e.m.f.'s of the two cells varied in a linear manner, and that a plot of the emf. of the one cell against the e.m.f of the other did give a straight line of the correct slope. This proved that the glass electrode functions properly in the medium. It further shows that the empirical calibration obtained at one pH is valid over a wide range of pH values, provided that the solvent fraction and total ionic concentrations remain constant.

Discussion of Ionic Strength. Tables (55, 63, 64, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, and 102) give data for 50 volume °/o dioxane which was also made up to ionic strength = 0.10 by the addition of potassium nitrate. Here the correction is negative 0.08 units as found by a similar titration of nitric acid; the meter readings were 0.08 units higher than the values calculated assuming complete dissociation. Here the assumption of complete dissociation is probably much less accurate because the reaction H+ + N0~ = HNO^ is displaced to the right by the considerable excess of nitrate ions. This matter of incomplete dissociation is a good reason for not adding inert electrolyte to attain high ionic strengths, especially in this non-aqueous solvent medium. Among approximately twenty-five papers concerned with the determination of metal chelate stability, only one was found in which the ionic strength was raised to a high level by the addition of inert salt when the solvent medium was water-dioxane. This paper, by Irving and hrs. Rossotti (4 6), describes the use of SO SO dioxane-water and states, "A salt background of 0.3 m. NaCIO was used throughout, since in this mixed solvent the rate of change of activity coefficient with ionic strength is likely to be small at this concentration." In an article on the determination of thermo dynamic equilibrium constants in mixed solvents van uitert and Femelius (4 8) recommend the use of dilute solutions. They state that: "It is undesirable to add an inert electrolyte". All of Harris's experiments were run without added salt, and a majority of the data recorded in the literature are at very low ionic strength and at concentrations of reactants similar to those used by Harris and in the present work. In discussing their results in 75$ volume dioxane and 25$ volume watSr van Uitert, etal (5l) state that: "The divalent metal salts are extensively associated beyond, the degree expected to conform with strong electrolyte behavior. This association does not appear to be the case for the nitrate or perchlorate salts of the monochelated divalent cations of Mg, Mn, Co, Zn, Hi, He, and Cu." They point out that the true relation between the successive formation constants may be changed by the strong association of the nitrate and perchlorate ions with the unchelated cations. It appears likely that the addition of inert electrolyte would not help this situation. van Uitert,etal (5l) found that even without adding inert electrolyte, the values of the first formation constants increased as the anion associated with the divalent cation added was changed from cliloride to nitrate to perchlorate. The largest differences occurred between chloride and nitrate, but even between nitrate and perchlorate there was often a difference of 0.3 log units for the first formation constants, van Uitert, etal (52) point out that the chelation reactions are not as simple as the equations which have been given in the Bjerrum development, but that the following equations better describe the equilibria:

"M(N03 )2 (H20)x + HCh = M(N05)ch(H20)y + + (x - y)H20 and

3 )Ch(H20)y + HCh = M(Ch)2(H20)a + HN03 + (y - z )E20"

The best reason for adding inert electrolyte would be to attain a high ionic strength which would not be relatively changed very much during the titration experiments. This would have the result that activity coefficients for the various species present in the solution would remain constant. The result of this should be that the values of the formation constants obtained under varying concen trations of reactants should be less subject to change. This is the point that Irving and Mrs. Rossotti (4 6) have made. If the addition of inert electrolyte to attain a relatively high ionic strength did result in better agreement among the answers obtained, then the addition of inert electrolyte would be desirable in spite of the increased association difficulties mentioned above. To investigate this possibility, the titrations of 2-(aminomethyl) benzoic acid were run in two ways. In the first set of experiments the titrations were run at low ionic strengths with no added salt. These experiments are recorded in Tables 81 through 91. Here fifteen pairs of answers had an average difference of 0.17 log units, and a considerable part of the total of the differences was due to just one pair. A "pair of answers" means two values for the same constant, one value obtained from titration _3 data for which the concentration of metal was about 1.0 x 10 , the second value obtained from data for which the concentration of metal -3 was about 0.5 x 10 In the second set of experiments the titrations were run at an ionic strength of 0.10 attained by the addition of KRO^. These results are recorded in Tables 9 2 through 102. Here fifteen pairs of answers had an average difference of 0.15 log units, which is no real improve ment. At this ionic strength the pK values of the acid had decreased, Q. possibly because of complex formation with the potassium ion. Except for cadmium, the formation constants are smaller at this higher ionic strength. This could be the result of a higher degree of association with the nitrate ions, but it could also be associated with the lower pK& values of the acid. Similar data are given for the titration of trimethylene dianthranilic acid in Table 55 and for its reaction with copper in Tables 63 and 6 4. The titration of N-(aminoethyl)-anthranilic acid in the presence of copper is given in Table 76 and is typical of the changes in ionic strength which occur. Before any base was added, the ionic strength was 1.384 x 10”^; at n = 0.5, pi = 1.238 x 10 at n = 1.0, = 1.147 x 10 and at n = 1.5, = 1.126 x 10”^. These changes in ionic strength during the titration of a 0.01 M solution of acid with 0.2 N base are not as large as one might at first expect. In the figures and tables concerned with the titrations of the acids in the absence of divalent metal ions, values of "a" are given. In general, nitric acid was present in addition to the weak acid, and the number of moles of the two acids was not exactly the same. In these titrations the nitric acid was titrated first, and the values of "a" between 0 and 1 were based on the number of moles of nitric acid known to be present. Then the weak acid is titrated, and the values of "a" higher than 1 are based on the number of moles of weak acid. 61 Table 5. Titration of anthranilic acid in 50 volume $ dioxane.

HI. base pH™ a * Corr.

0.000 2.37 0.000 2.000 3.07 0.81 2.440 4.07 0.986 2.482 4.58 1.003 2.550 5.18 1.029 2.700 5.67 1.086 3.000 6.08 1.200 3.500 6.48 1.390 3.600 6.56 1.429 3.700 6.62 1.466 3.810 6.68 1.509 4.600 7.28 1.810 5.000 8.07 1.961 5.065 8.49 1.985 5.100 9.06 2.000 5.165 10.79 2.023 pka = 6 . 6 6

5.00 x 10 4 moles HNO^ and 5.20 x 10~4 moles A. A. Total initial volume, 98.7 ml. Equal volumes of dioxane and 0.2007 N NaOH added. 35°C. ______I______1______I______I__ 0.0 0.50 1.00 1.50 2.00 a O' FIGURE 16. pH-a CURVE FOR ANTHRANILIC ACID FROM TABLE 5- w 63 Table 6. Titration of anthranilic acid and cobalt with ,-3 7~ = OjSGx10'

Ml. base n pR ^Corr. 2.520 4.87 0.04 4.11 2.625 5.29 0.19 3.71 C11 = 2.720 5.55 0.23 3.47 2.820 5.69 0.37 3.35 (log 1^)72=2.81 3.020 5.95 0.54 3.13 3.230 6.15 0.69 2.98 2 3.500 6.37 0.92 2.84 3.82 6.59 1.185 2.73 4.110 6.79 1.47 2.65

In the total -3 c initial volume of 98.7 ml., A = 5.02 x 10 » GI _3 10“3 , CM = 0.60 x 10 . Equal volumes of dioxane and 0.200:

50 volume fo

Table 7. Titration of anthranilic acid and cobalt with C. = ______i'i

1.20xl0~5 .

Kl. base n PR ^Corr. 2.510 4.76 0.025 4.23 2.604 5.19 0.095 3.81 C 2.710 5.47 0 .14 3.55 1 2.840 5.69 0.21 3.36 3.045 5.95 0.31 3.14 3.250 6.15 0.39 2.99 3.520 6.35 0.57 2.88 3.710 6.49 0.655 2.80 3.980 6.69 0.755 2.70 4.260 6.94 0.795 2.60

In the total initial volume of 98.7 ml., A = 5.02 x 10~3 , -3 -3 10 , (I, = 1.20 x 10 . Equal volumes ox aioxane and 0.2001 N IfeOH added. 50 volume 7 dioxane. 35°C. 64 Table 8. Titration, of anthranilic acid and nickel with C m 0.547x10""'’

Ml. base pH ^Corr. n

2.500 4.67 0.075 4.40 2.620 5.19 0.27 3.83 C. = 3.30 «L 2.710 5.47 0.35 3.57 2.805 5.67 0.405 3.38 (log kjk2)/ 2.945 5.86 0.57 3.23 6.05 0.72 3.08 G =(2.53) 3.115 d. 3.340 6.26 0.88 2.93 3.552 6.45 0.925 2.81 3.830 6.64 1.17 2.72 4.135 6.86 1.31 2.63

In the total initial volume of 98.7 ml., A = 5.02 x 10'"5, C = 4.91 10 3, c = 0.547 Equal volumes of dioxane and 0.2001 N NaOH added. 50 volume ft dioxane. 35 0.

Table 9* Titration of anthranilic acid and nickel with =

1.094x10=r

Ml. base. pR pHCorr. n

2.580 4.89 0.125 4.11 2.690 5.20 0.255 3.82 Cx = 3.41 2.780 5.42 0.32 3.62 2.895 5.58 0.49 3-48 (log k1k2)/2=2.89 3.100 5.85 0.605 3.26 3.395 6.11 0.86 3.07 C2 = (2.62) 3.600 6.31 0.94 2.94 3.880 6.53 1.07 2.82 4.185 6.76 1.29 2.73 4.50 6.99 1.82 2.72

the .total initial volume of 98.7 ml., A = 5.02 x 10“ -3 -3 R 10 , C = 1.094 x 10 . Equal volumes of dioxane and 0.2001 11 NaOH - o added. 50 volume c/o dioxane. 35 C. 65 Table 10. Titration of anthranilic acid and zinc with =

0.57xl0~3 .

Ml. base pHCorr. n PR

2.484 4.58 0.055 4.44 2.585 5.18 0.20 3.86 C1 = 3.16 2.685 5.49 0.28 3.58 2.780 5.70 0.37 3.39 2.890 5.87 0.445 3.24 3.020 6.03 0.54 3.12 3.200 6.22 0.655 2.98 3.395 6.42 0.655 2.85 3.600 6.61 0.62 2.74

In the total initial volume of 98.7 ml., A = 5.02 x 10“3 , CQ = 4.34 x 10 , = 0.57 x 10 . Equal volumes of dioxane and 0.2001 N NaOH .added. 50 volume $ dioxane. 35 C.

Table 11. Titration of anthranilic acid and zinc with

1.14 x 10"3 .

Ml. base pHn pR r Corr. n

2 .5 0 0 4.63 0.03 4.34 2.600 5.04 0.15 3.95 C = 3.21 2.700 5.32 0.23 3.69 2.810 5.52 0.325 3.51 2.920 5-67 0.41 3.38 (log k1k2)/2=2.90 3.010 5.80 0.465 3.28 3.120 5.92 0.54 3.18 3.270 6.08 0.61 3.06 3.375 6.21 0.61 2.97 3.760 6.42 1.09 2.89

_3 In the total initial volume of 98.7 ml., A = 5.02 x 10 , CD = 4.90 x -3 -3 10 , Cjj = 1.14 x 10 . Equal volumes of dioxane and 0.2001 N NaOH added. 50 volume ^ dioxane. 35 C. 66

Table 12. Titration of N-methyl anthranilic acid in 50 volume % dioxane.

Ml. base. pEL a * Gorr.

0.000 2.37 0.000 2.000 3.06 0.810 2.400 3.89 0.970 2.460 4.58 0.994 2.534 5.17 1.021 2.600 5.44 1.045 3.000 6.06 1.189 3.500 6 .4 6 1.368 3.800 6.6.5 1.479 3.900 6.70 1.511 4.800 7.39 1.835 5.100 7.87 1.943 5.185 8.21 1.972 5.220 8.42 1.985 5.320 10.67 2.022 pk = 6.68 * a

5.00 x 10 4 moles HNO and 5*59 x 10 4 moles of A.A. Total initial 5 volume, 98.7 ml. Equal volumes of dioxane and 0.2007 N NaOH added. 35°C. 12

0.0 0.50 1.00 1.50 2.00 a

FIGURE 17. pH-a CURVES FOR N-METHYL ANTHRANILIC ACID FROM TABLES 12 AND 18. 68 Table 13. Titration of N-methyl anthranilic acid and cobalt

with Cjj = 0.60 x 10

Ml. base pR ^Corr. n

2.525 4.59 0.16 4.43 2.630 5.24 0.245 3.80 = 3.27 2.730 5.51 0.37 3.55 2.837 5.70 0.425 3.36 (log k1k2 )/2=2.84 2.940 5.86 0.53 3.24 3.070 6.01 0.635 3.12 C2=2.67 3.270 6.20 0.81 2.98 3.485 6.38 1.02 2.87 3.680 6.55 0.95 2.76 3.890 6.69 1.13 2.70 4.095 6.80 1.70 2.68 4.300 6.99 1.73 2.62 -3 l the total initial volume of 98.7 ml., A = 5.02 x 10' , CR = 4.96 x 10 5 , C = 0.60 x 10"5 Equal volumes of dioxane and 0.2001 N NaOH ’ m added. 50 volume $ dioxane. 35°C.

Table 14. Titration of N-methyl anthranilic acid and cobalt

with CTT = 1.20 x 10 M

11. base pR pHCorr. n

2.610 5.01 0.05 4.01 2.720 5.33 0.245 3.71 C1 = 3.16 2.820 5.59 0.28 3.47 3.190 5.94 0.655 3.20 (log 2 = 2 . 1 6 3.31 6.14 0.575 3.03 3.490 6.29 0.69 2.94 C =2.69 3.658 6.40 0.795 2.88 3.910 6.59 0.905 2.78 4.130 6.75 1.285 2.78 4.520 7.05 1.58 2.69 -3 In the total initial volume of 98.7 ml., A = 5.02 x 10 5.09 x CR 10,-3= 1.20 x 10 ,-3 Equal volumes of dioxane and 0.2001 N NaOH added. 50 volume $ dioxane. 35°C. Table 15. Titration of N-methyl anthranilic acid and nickel

with = 0.547 x 10

Ml. base pR pHCorr. n

2.505 4.64 0.075 4.35 2.610 5.20 0.21 3.80 3.28 ° i - 2.710 5.49 0.31 3.53 2.810 5.67 0.435 3.37 (log kik2)/2=2 2.940 5.85 0.57 3.22 11 3.120 6.05 0.66 3.06 0 2.70 3.345 6.21 0.82 2.95 i\) 3.560 6.39 1.16 2.83 3.880 6.60 1.24 2.72 4.210 6.80 2.00 2.66 4.490 6.99 2.93 2.64

-3 . the total initial volume of 98.7 ml., A = 5.02 x 10' 'R 10"3, CM = 0.547 x 10~3 . Equal volumes of dioxane and 0.2001 N NaOH added. 50 volume fo dioxane 35°C.

Table 16. Titration of N-methyl anthranilic acid and nickel

with CM = 1 .0 9 4 x 10~3 .

Ml. base PH,Corr. n pR

2.635 5.09 0.18 3.91 2.740 5.37 0.285 3.65 C1 = 3.22 2.845 5.57 0.35 3.47 2.990 5.77 0.445 3.29 (log ^ 2 )72=2.93 3.160 5.95 0.58 3.15 3.445 6.17 0.835 3.01 C2=2.77 3.780 6.39 1.13 2.88 4.080 6.58 1.39 2.80 4.520 6.91 1.78 2.70 4.820 7.17 2.45 2.73

-3 In the total initial volume of 98.7 ml., A = 5.02 x 10' CR = 5.40 x 10"3 , C.j. =- 1.094 ^x 10"3 ., Equal volumes of dioxane and 0.2001 N NaOH added. 50 volume jB» dioxane. 35°C. 70 Table 17. Titration of N-methyl anthranilic acid and zinc

with CH = 0.57 x 10~3 .

11. base n pR ^Corr.

2.600 5.08 0.26 3.93 2 .7 0 0 5.40 0.40 3.63 C1JL = 2.900 5.76 0.585 3.31 3.100 5.99 0.78 3.12 (log 3.300 6.19 0.88 2.97 3.616 6.45 1.02 2.80 (2.55) C?C. = 4.000 6.74 1.065 2.64 4.300 6.95 1.37 2.57 4.630 7 . 2 2 2.46 2.57 -3 In the total initial volume of 98.7 ml., A = 5*02 x 10 , C_ = 5.22 x -3 -3 10 , = 0.57 x 10 . Equal volumes of dioxane and 0.2001 N NaOH added. 50 volume °/> dioxane. 35°C.

Table 18. Titration of N-methyl anthranilic acid and zinc with

CM = 1.14 x 10"3 .

Ml. base PR pHCorr. n

2.600 4.89 0.155 4.12 2.700 5.19 0.29 3.84 = 3.42 2.800 5.41 0.35 3.63 2.910 5.58 0.445 3.48 (log ^ 2 )72=2 .9 8 3.020 5.71 0.555 3.38 3.220 5.95 0.71 3.19 C2=2.76 3.420 6.10 0.905 3.09 3.630 6.29 1.02 2.96 3.900 6 .4 8 1.20 2.86 4.200 6.70'. 1.445 2.77 4.590 7.04 1.84 2.70 -3 In the total initial volume of 98.7 ml., A = 5.02 x 10 , 0o = 5.24 x -3 -3 10 , = 1.14 x 10 . Equal volumes of dioxane and 0 . 2 0 0 1 N NaOH added. 50 volume $ dioxane. 35 C. zo

0.8

0 .4

0.0 2.5 2.7 2 .9 3.1 3 .3 3 .5 3 .7 3 9 4.1 4 3 pR

FIGURE 18- n-pR CURVE FOR N-METHYL ANTHRANILIC ACID AND ZINC FROM TABLE 18. 19. Titration of 2,2'imino dibenzoid acid in 50 volume T> dioxane.

Ml. base a ^Corr. 0.000 2.31 6.o0c3 0.511 2.41 0.207 1.038 2.54 0.420 1.611 2.77 0.652 2.058 3.07 0.832 2.376 3.60 0.961 2.427 3.90 0.983 2.494 4.31 1.010 2.526 4.49 1.025 2.626 4.85 1.069 2.756 5.07 1.118 2.901 5.32 1.191 3.180 5.58 1.315 3.224 5.82 1.334 3.876 6.03 1.624 4.226 6.23 1.779 4.434 6.34 1.827 4.706 6.50 1.993 4.816 6.57 2.042 4.984 6.66 2.114 5.258 6.80 2.238 -4 -4 4.52 x 10 moles of B.A. and 5.00 x 10 moles of HNO . Total initial volume, 98.7 ml. Titrated with 0.2007 N NaOH at 35°C. 73 Table 19. Continued

5.616 7.00 2.394 5.866 7.13 2.507 6.421 7.57 2.750 6.764 8.03 2.905 6.896 8.53 2.965 6.926 8.81 2.978 6.958 9.32 2.99 6.974 9.80 3.00 6.988 10.34 3.005 7.048 11.03 3.03 7.236 11.62 3.12

Cl = 5 .95 < = 7.12

Convergence correction is 0.10.

6.05 l*a2 => 7.02

By Schwarzenbach1s graphical method: o o •

6.0 5 -f*- ?kal = + 0.15 pk&2 = 6.99 ± 12

0.0 0.4 0.8 1.2 1.6 2.0 2.4 3.2 a

FIGURE 19. pH -a CURVE FOR 2 ,2 ' IMINO DIBENZOIC ACID FROM TABLE 19 £ Table 20. Titration of 2,2' imino dibenzoic acid and cobalt with = 0.60 x 10“3 .

HI. base n pR 2.480 4.22 0.01 6.91 2.590 4.57 0.07 6.22 2.690 4.74 0.18 5.90 log k = 5.03 2.800 4.90 0.28 5.59 2.850 5.02 0.35 5.36 2.900 5.11 0.44 5.20 3.200 5.29 0.57 4.87 3.620 5.61 0.82 4.31 3.830 5.73 0.925 4.12 4.150 5.92 1.03 3.83 4.480 6.10 0.98 3.56 4.780 6.26 0.99 3.35 4.900 6.32 0.97 3.28

In the total initial volume of 98.7 ml. , A = 5*06 x ] 3“5, CR = 5.15 x , -,- 0^ 10-3, cH = 0.,60 x lO-3. Titrated with 0.2007 N NaOii fa dioxane.

Table 21. Titration of 2,2' imino dibenzoic acid and cobalt

with C = 1.20 x 10~3 . M

Ml. base pR pHCorr. n 2.486 4.03 0.04 7.27 2.579 4.34 0.06 6.66 log k = 5.18 2.686 4.52 0.12 6.31 2.780 4.67 0.25 6.03 2.890 4.77 0.29 5.83 3.030 4.89 0.34 5.61 3.200 5.02 0.425 5.37 3.330 5.12 0.495 5.19 3.640 5.29 0.685 4.90 4.040 5.52 0.87 4.51 4.350 5.69 1.00 4.23

In the total initial volume of 98.7 ml., A = 5.06 x ; Gr = 5.39 x 10""3, C.. = 1.20 x 10 3 . Titra ted with 0 . 2007 h naOii }j dioxane. Q 8

0.6 -

0.4-

0.2

0.0 3 2 3.6 4.0 4.4 4 85.2 5.6 6.0 6.4 6.8

FIGURE 20. n-pR CURVE FOR 2 ,2 ' IMINO DIBENZOIC ACID AND COBALT FROM CTi TABLE 20. Table 22. Titration of 2,2' imino dibenzoic acid and cobalt

with = 2.40 x 10~3 .

111. base pH_ — pR i Corr. n r

2.416 5.78 0.01 7.76 2.490 4.01 0.02 7.50 log k = 5.19 2.582 4.25 0.05 6.85 2.780 4.55 0.12 6.25 2.998 4.72 0.20 5.95 5.202 4.87 0.28 5.65 5.400 4.98 0.56 5.45 5.700 5.12 0.49 5.21 5.940 5.22 0.58 5.04 4.252 5.52 0.71 4.88 4.560 5.47 0.85 4.65 4.790 5.58 0.91 4.45 5.020 5.70 1.00 4.25

In the total initial volume of 98.7 ml., A = 5.02 x 10 3, CR = 5.24 10“3, CM = 2.40 x 10~3. Titrated with 0.2007 N NaOH at 35°C. 50 volume fo dioxane. 78 Table 25. Titration of 2,2' imino dibenzoic acid and nickel

with CM = 0.547 x 10~3 .

Ml. base pR pHCorr. n

2.020 3.04 0.00 9.29 2.490 4.12 0.07 7.13 2.590 4.47 0.09 6.45 log k = 5.48 2.870 4.910 0.425 5.60 5.080 5.12 0.675 5.21 5.520 5.34 0.82 4.80 3.570 5.53 1.02 4.48 3.800 5.71 1.07 4.18 3.990 5.81 1.11 4.02 4.180 5.93 1.08 3.84 4.440 6.08 1.16 3.62

In the total initial volume of 98.7 ml., A = 5.06 x 10"3, C = 4.89 10"3 , CM =0.547 x 10” . Titrated with 0.2007 N NaOH at 35 C. 50 volume fo dioxane,•

Table 24. Titration of 2,2' imino dibenzoic acid and nickel

with CM = 1.641 x 10"3 .

Ml. base pH •^Corr. n

2.380 3.6b o.oo 8.99 2.540 4.11 0.04 7.10 2.670 4.38 0.09 6.58 log k = 5.40 2.790 4.52 0.15 6.31 3.005 4.72 0.25 5.93 3.250 4.88 0.375 5.64 3.520 5.02 0.51 5.39 3.810 5.17 0.72 5.13 4.210 5.38 0.835 4.77 4.620 5.61 0.895 4.38 5.050 5.83 1.11 4.05 5.490 6.12 1.135 3.63 5.750 6.27 1.17 3.45

In the total initial volume of 98.7 ml., A = 5.06 x 10“3 , CR = 5.55 x 10"3 , CM = 1.641 x 10~3 . Titrated with 0.2007 N NaOH at 35°C. 50 volume io dioxane. 79 Table 25. Titration of 2,2* imino dibenzoic acid and copper with CL, = 0.35 x 10*°. ______H______

H I . base pH_ — v Corr. n pR

1.500 2.73 0 .0 0 9 .8 8 2.027 3.03 0.03 9.29 log k = 8.05 2.240 3.23 0.16 8.89 2.380 3.41 0 .2 1 8.53 2.480 3.53 0.40 8 .3 0 2.590 3.72 0.56 7.93 2.690 3.92 0.69 7.53 2.865 4.53 0.915 6.33 2.970 4 .8 8 0.97 5.65 3.080 5.08 1.05 5.26 3.180 5.22 1.115 5.00 3.280 5.34 1.16 4.78 3.460 5.52 1.2 1 4.46 3.640 5.64 1.305 4.26 3.880 5.81 1.33 3.98 4.280 5.98 1.83 3.74 4.600 6.13 2.17 3.54 In the total initial volume! O f 98.7 ml., A = 5.02 x 10'-3 CR = 5.15 x 10"3 , CM = 0.35 x 10 . Titrated with 0 .2007 H NaOH a' ?°C. 50 volume * ft dioxane.

Table 26. Titration of 2 ,2 1 imino dibenzoic aci< _3 with C,,. = 1.40 x 10 . i?i

HI. base pR ^Corr. n

1.510 2.72 0.04 9.94 1.860 2.88 0 .0 2 9.6 2 log lc = 8 .0 5 2.200 3.10 0.08 9.19 2.440 3.27 0.16 8 .8 6 In the total initi 2.580 3.36 0.2 2 8.69 al volume of 9 8.7 2.750 3.47 0.304 8.48 ml., A = 5.02 x 2.960 3.59 0.43 8.2 6 10-3, CR = 4 .7 9 x 3.170 3.720 8 .0 1 0.487 10-3, CM = 1 .4O x 3.380 3.870 0.69 7.74 10“3. Titrated 3.590 4.04 0.82 7.43

3.830 4.50 0.955 6.54 with 0.2007 N NaOH 3.930 4.79 0.986 5.98 at 35°C. 50 volume °/o dioxane. 4.040 5.02 1.02 5.54 4.250 5.32 1.21 5.0 1 4.610 5.68 1.2 2 4.38 0.8 -

0.4

0 01____I_I 1--- 1--- 1--- 1--- 1-- 1 u 3.2 4.0 4.8 5.6 6.4 PR

FIGURE 21. n-pR CURVE FOR 2 ,2 ' IMINO DIBENZOIC ACID AND COPPER CD o FROM TABLE 25. 81 Table 27. Titration of 2 ,2 ' imino dibenzoic acid and zinc with Ct, = 0.57 x 10-3.

base pR til. pHCorr. n

2.4 0 0 3.72 0 .0 0 7.93 2.500 4.13 0.0 0 7 .1 2 log k = 5.62 2.600 4.43 0.085 6.53 2.740 4 .6 8 0.28 6.05 2.870 4.87 0.43 5.69 3.040 5.05 0.60 5.35 3.240 5.24 0.825 5.0 1 3.510 5.47 0.99 4.60 3.780 5.6 6 1.15 4.28 4.030 5.82 1.26 4.02 4.320 6.0 2 1.24 3.72 4.520 6.1 1 1.45 3.61

In the total initial volume of 9 8 .7 ml., A = 5.02 x 10"5 , CR = 4.84 x 10"5 , C = 0.57 x 10 . Titrated with 0,.2007 N NaOH at 35 °0 50 volume $ dioxane. Table 28. Titration of 2 ,2 ' imino dibenzoic acid and zinc with 5i..=..V.71x 10-3. hi. base pH ^Corr. n 2.360 3.59 0 .0 0 8.19 2.460 3 .8 8 0.0 1 7.61 log k = 5.49 2.530 4.07 0.0 2 7.24 2.630 4.28 0.07 6.83 2.740 4.42 0.135 6.56 2.870 4.58 0.195 6.25 3.0 1 0 4.69 0.255 6.05 3.230 4.82 0.375 5.82 3.510 5.02 0.502 5.46 3.790 5.17 0.640 5.2 0 4.1 1 0 5.35 0.79 4.90 4.430 5.55 0 .9 0 4.57 4.810 5.79 1.035 4.20 5.130 6.0 1 1.09 3.87

In the total initial volume of 98.7 ml., A = 5*02 x 10 , CR = 4.88 x -3 10-3, CR = 1.71 x 10' Titrated with 0.2007 N NaOH at 35 C. 50 volume Jo dioxane. Table 29. •Titration of 2 ,2 ' imino dibenzoic acid and cadmium with C.. = 1.05 x 10-3. h

HI. base pR ■^Corr. n

2.418 3.69 0.03 7.97 2.520 3.98 0.07 7.32 2.668 4.29 0.18 6.79 log k = 5.79 2.800 4.50 0.27 6 .3 8 2.978 4.70 0 .4 0 6 .0 0 3.185 4 .8 8 0.56 5.67 3.500 5.10 0.78 5.27 3.822 5.30 1 .0 1 4.92 4.216 5.52 1.26 4.55 4.606 5.74 1.50 4 .2 0 4.962 5.96 1.5 6 3.87 5.342 6.2 1 1.5 6 3.53 In the total initial volume of 9 8 .7 ml., A = 5.06 x 10"3 , CR = 5.19 x 10‘3 , CB . 1.05 x 10 . Titrated with 0,.2007 N NaOH at 35°C. 50 volume cf> dioxane. Table 30. Titration of 2 ,2 ' imino dibenzoic acid and cadmium with CM = 2 .1 0 x 10-3.

I'll, base pHn pR - Corr. n 2.412 3-62 0.03 8.06 2.517 3.82 0.05 7 .6 6 2.730 4.19 0 .1 2 6.94 log k = 5 .7 0 3.050 4.50 0.25 6.35 3.300 4 .6 8 0.35 6 .0 1 3.544 4.79 0.46 5.82 3.942 4.98 0 .6 1 5.41 4.334 5 .1 2 0.79 5.25 4.726 5.28 0.95 4.99 5.1 2 2 5.42 1 .1 0 4.78 5.505 5.60 1.225 4.51 5.942 5.83 1.40 4.16

In the total initial volume of 98.7 ml., A = 5.06 x 10~3, CL = 5.85 x 10 , CM = 2.10 x 10 . Titrated with 0.2007 N NaOH at 35°C. 50 volume °/o dioxane. 83 Table 31. Titration of 2,2' hydrazo dibenzoic acid in 50 volume

° /o dioxane.

■il. base a pHCorr.

0.000 2 .3 2 0.000 0.530 2.42 0.214 1.050 2.57 0.425 1.532 2.73 0.620 2.0 3 0 3.06 0.821 2.238 3.32 0.905 2.326 3.56 ■0.941 2.432 3.99 0.984 2.470 4.18 1.000 2.535 4.48 1.025 2.567 4.60 1.037 2 .6 9 0 4.97 1.046 3.027 5.38 1.215 3.264 5.56 1.306 3.636 5 .8 0 1.448 4.060 5.98 1.612 4.374 6.17 1.734 4.760 6.27 1.862 4.963 6 .3 6 1.958 5 .1 0 0 6.40 2.012 5.240 6.45 2.064 5.632 6.61 2.217 6.400 6.94 2.51 6.9 6 0 7.30 2.725 7.200 7.48 2.82 7.385 7.77 2.890 7.480 8 .0 0 2.928 7.600 8 .4 8 2.972 7.660 9.78 2.995 7.680 10.58 3.005 84

Table 31 Continued.

7.804 11.23 3.050 8.030 11.70 3.14

= 5.86 C2 = 6.93

pk = 5.99 pk _ = 6.80 , using a correction of al 0.13. From Schwarzenbach1s graphical method:

pk&^ = 5.93 ^ 0.06 P^a2 = i. 0.02

5.22 x 10 4 moles of B.A. and 5.00 x 10~4 moles of HN0_. Total final 3 volume, 98.7 ml. Titrated with 0.2007 N NaOH at 35 C. J______I______I______I______I______I______I______L 0.0 0.4 0.8 1.2 1.6 2.0 2.4 2.8 3.2 a

FIGURE 22. pH-a CURVE FOR 2,2' HYDRAZO DIBENZOIC ACID FROM ® TABLE 31. 86 Table 32. Titration of 2.2* hydrazo dibenzoic acid and cobalt with 0H = 0.60 x 10-3.

Ml. base pR •^Corr. n 2.700 4.89 0.04 5.35 2.9 0 0 5.18 0 .1 2 4.85 3.125 5.37 0.28 4.62 log k = 3.92 3.420 5.57 0.32 4.13 3.700 5.72 0.555 3.92 4 .0 2 0 5.89 0.65 3.61 4.310 6.04 0.33 3.41 4.600 6.16 0.42 3.27 In the total initial volume of 9 8 .7 ml., A = 5.06 x 10"3 , CR = 5.19 10“3 , CH = 0.,60 x 10 . Titrated with 0.2001 N NaOH at 35°C. 50 VC fo dioxane.

Table 33• Titration of 2,2* hydrazo dibenzoic acid and cobalt with CM = 1.80 x 10 M

Ml. base pR pHCorr. n

2.610 4.52 0.035 6.13 2.700 4.73 0.06 5.72 2.880 4.98 0 .1 1 5.25 3 .1 2 2 5.19 0.18 4.87 3.560 5.38 0.245 4.54 3.600 5.52 0.30 4.30 3.940 5.69 0.395 4.03 4.280 5.85 0.42 3.75 4 .64O 5.99 0.59 3.62 5.050 6.19 0.645 3.37 5.460 6.38 0.73 3.17 5.900 6.61 0.79 2.98

In the total initial volume of 98.7 ml., A = 5.02 x 10 3, CL = 4.85 x •7 -x A 10 J, = 1.80 x 10 , Titrated with 0.2007 N NaOH at 35°C. 50 volume f< > dioxane. 87 Table 34. Titration of 2,2* hydrazo dibenzoic acid and nickel with CM = 0.55 x 10-3,

Ml. base pH„ — pR ■^Corr. n r

2.450 4.08 0.045 6.93 2.620 4.70 0.03 5.71 2.720 4.89 0.08 5.35 log k = 3.92 2.900 5.12 0.16 4.92 3.150 5.34 0.29 4.52 3.370 5.49 0.36 4.25 3.580 5.61 0.495 4.05 3.910 5.78 0.495 3.78 4.240 5.92 0.90 3.62 In the total initial volume of 98.7 ml., A = 5.02 x 10""^, C = 5.60 x ~ A ^ 10"°, CM = 5.50 X 10 . Titrated with 0.2007 N NaOH at 35°C. 50 volume % dioxane.

Table 35. Titration of 2,2* hydrazo dibenzoic acid and nickel with C,, = 1.65 x 10 .

Ml. base pR ^Corr. n

2.600 4.64 0.015 5.93 2.775 4.93 0.14 5.60 log k = 3.75 2.990 5.20 0.135 4.90 3.190 5.37 0.19 4.60 3.490 5.56 0.27 4.28 3.850 5.73 0.40 4.02 4.210 5.92 0.50 3.75 4.340 5.98 0.525 3.67 4.880 6.22 0.71 3.40 5.450 6.49 0.945 3.18

In the total initial volume of 98.7 ml., A = 5.02 x 10' ^ t — 4•29 x 10-3, C = 1.65 x lO”3 . Titrated with 0.2007 N NaOH at 35°C. 50 volume °/o dioxane. 88

Table 36. Titration of 2j 2 ' hydrazo dibenzoic acid and copper ------with C = 0.70 x 10 . M

U. base P**Corr. n pR

2 .0 3 0 2 .9 8 0.12 9.17 2.260 3.14 0.18 8 .8 6 2.360 3.26 0 .21 8.62 2.460 3.37 0.265 8 .4 1 log k = 7.80 2.570 3.50 0.36 8.15 2.680 3.62 0.465 7.92 2.810 3.82 0.565 7.53 2.990 4.18 0.72 6.83 3.130 4.50 0.845 6.20 3.270 4.79 0.955 5.64 3.410 5 .0 0 1.035 5.24 3.590 5 .2 0 1.165 4 .8 8 3.760 5.34 1.265 4.63 3.980 5.49 1.43 4.37 _3 In the total initial volume of 98.7 ml., A = 5.02 x 10 , = 5.12 x 10“5, CM = 0.70 x 10“5. Titrated with 0.2007 N NaOH at 35°C. 50 volume f> dioxane. Table 57. Titration of 2,2' hydrazo dibenzoic acid and copper with CM = I.4O x 10-3,

Ml. base pR pHCorr. n 2.000 2.92 0 .1 0 9.32 2.320 3.12 0.15 8.93 log k = 7.93 2.455 3 .2 1 0 .2 0 8.75 2.600 3.32 0.26 8.54 2.810 3.46 0 .3 6 8.28 .3.030 3.62 0.47 7.98 3.310 3 .8 6 0.62 7.52 3.640 4.23 0.835 6.82 3.840 4.62 0.94 b .06 3.970 4 .8 1 1 .0 0 5.71 4.080 4.94 1.05 5.47 4.260 5.13 1.19 5 .1 2 4.440 5.30 1 .21 4.82 In the total initial volume of 98.7 ml., A = 5.02 x 10~^, = 4.92 x 10-5, CM = 1.40 x 10”5 . Titrated with 0.2007 N NaOH at 35°C. 50 volume fo dioxane. Table 38. Titration of 2,2* hydrazo dibenzoic acid and zinc with CM = 0.57 x 10-3.

Ml. base pR ■^Corr. n

2.540 4.32 0.04 6.45 2.680 4.70 0.125 5.71 2.780 4.88 0.22 5.36 log k = 4.50 2.950 5.08 0.32 4.99 3.050 5.32 0.485 4.54 3.550 5.52 0.645 4.21 3.850 5.70 0.87 3.90

In the total initial volume of 98.7 ml., A = 5.02 x 10“3, CR = 5.70 : 10 3 , CM = 0.57 x 10~3 . Titrated with 0.2007 N NaOH at 35°C. 50 volume fo dioxane.

Table 39. Titration of 2,2* hydrazo dibenzoic acid and zinc with CTT = 1.71 x 10-3. K

Ml. base pH^, — pR Corr. n *

2.5 0 0 4.28 0.00 6.68 2.690 4.69 0.08 5.89 log k - 4.73 2.820 4.90 0.15 5.49 3.000 5.08 0.185 5.16 3.320 5.32 0.30 4.74 3.640 5.52 0.42 4.41 4.000 5.72 0.54 4.11 4.300 5.90 0.615 3.85

In the total initial volume of 98.7 ml., A = 5.02 x 10~3, C = 4.03 x •Z ^ lO"^, CH = 1.71 X 10"^. Titrated with 0.2007 N NaOH at 35°G. 50 volume % dioxane. 90 Table 40. Titration of 2,2* hydrazo dibenzoic acid and cadmium with CT, = 1.036 x 10-3. M

Ml. base pR ^ Corr. n 2.462 3.92 0 .0 0 7.29 2.5 6 8 4.23 0.08 6.69 2.6 6 8 4.49 0.15 6.18 log k = 4.74 2.820 4.72 0.23 5.73 3.008 4.98 0.32 5.24 3.243 5.18 0.47 4 .8 8 3.520 5.39 0.57 4.51 3.860 5.60 0.69 4.16 4.280 5.82 0.83 3.82 4.770 6.07 0.92 3.47 5.820 6.58 1 .0 1 2.93

In the total initial volume of 98.7 ml., A = 5.02 x 10"3, CM = 5.04 x 10"3 , CM = 1.036 x 10"3 . 'litrated with 0.;2007 N NaOH at 35 C. 50 vc] fo dioxane. Table 41. Titration of 2 ,2 ' hydrazo dibenzoic acid and cadmium with CM = 2.072 x 10-3.

Ml. base pR •^Corr. n . 2,454 3.79 0 .0 0 7.55 2.557 4.08 0 .0 1 6 .9 8 2.692 4.33 0.09 6 .5 1 log k = 4 .6 8 2.832 4.56 0.14 6.06 2.970 4.71 0.19 5.77 3.144 4.87 0.25 5.48 3.392 5.05 0.34 5.15 3.712 5.23 0.45 4.84 4.052 5.42 0.535 4.52 4.370 5.59 0.695 4.25 4.722 5.75 0.76 4.02 5.OO5 5.89 0.83 3.82 5.330 6.08 0 .8 6 3.56 In the total initial volume of 98.7 ml., A = 5.02 x 10-3, Cp = 4.97 x -3 -3 10 C = 2.072 x 10 Titrated with 0.2007 N NaOH at 35 C. 50 volume c/o dioxane. Table 42. Titration of methylene dianthraniiic acid in

50 volume % dioxane.

Ml. base a

0.000 2.38 0.000 0.520 2.48 0.211 1.410 2.75 0.571 2.115 3.20 0.856 2.320 3.57 0.940 2.420 3.98 0.980 2.457 4.24 0.994 2.480 4.5b 1.006 = 6.11 C2 = 7.07 2.510 4.82 1.022 3.215 6.03 1.414 Convergence Corr. = 0.17. pka^ = 6.28 Pka2 = 6*90 4.123 6.52 1.920 4.195 6.57 1.960 From graphical soln. 4.380 6.65 2.062 pkal = 6.36 ± 0.05 4.510 6.72 2.135 pk&2 = 6.82 + 0.05 4.606 6.75 2.187 4.712 6.83 2.248 5.417 7.21 2.64 6.040 8.43 2.985 6.077 9.83 3.000 6.105 10.7 0 3.02

3.60 x 10 ^ moles of diA.A. and 5.00 X 10 ^ mole3 HNO . Total initial n 3 volume, 98.7 ml. Titrated with 0.2007 N NaOH at 35 C. 10 -

0.0 0 4 0.8 1.2 1.6 2.0 2.4 2.8 3 2 a

FIGURE 23. p H - a CURVE FOR METHYLENE DIANTHRANILIC ACID FROM TABLE 42. Table 43. Titration of methylene diantliranilic acid and

cobalt with - 0.60 x 10“^.

M l . base n pR ^Corr.

2.640 5.08 0.09 5.52 2.700 5.28 0.15 5.13 2.780 5.42 0.17 4.87 2.95 2.870 5.58 0.19 4.57 2.940 5.67 0.21 4.41 3.000 5.73 0.23 4.30 3.080 5.80 0.27 4.18 3.170 5.89 0.28 4.02 3.275 5.98 0.27 3.87 3.350 6.01 0.20 3.82 3.510 b.12 0.35 5.66 3.680 6.21 0.41 3.52 3.990 6.38 0.36 3.29 4.335 6.53 0.41 3.11 4.600 6.65 0.48 3.00 -■5 In the total initial volume of 98.7 ml., A = 5.06 x 10 , = 3.85 10"5 , CM = 0,60 x 10-5. Titrated with 0.2007 N NaOH at 35°C. 50 volume c/o dioxane. Table 44. Titration of methylene diantliranilic acid and

cobalt with C., = 1.20 x lO-^. 11

Ml. base t>H„ — " C o m . n

2.638 5.00 0.07 5.69 2.670 5.08 0.08 5.54 2.738 5.23 0.12 5.25 3.55 2.803 5.36 0.13 5.01 2.872 5.46 0.15 4.82 2.973 5.58 0.20 4.60 3.080 5.70 0.23 4.39 3.190 5.78 0.275 4.25 3.392 5.93 0.33 4.0U 3.693 6.12 0.415 3.71 4.115 b.32 0.565 3.44 4.525 6.51 0.67 3.22 5.045 6.65 1.11 3.17 In the total initial volume of 98*7 ml., A = 5.06 x 10 , CR = 3.73 l O^ , CM = 1.20 X 10 . Titrated with 0.2007 N NaOH at 35°C. 50 volume fo dioxane. Table 45. Titration of methylene diantliranilic acid and

nickel with C.,j = 0.547 x 10"5

Ml. base pR pHCorr. n

2.612 5.00 0.08 5.66 2.670 5.18 0.135 5.31 2.740 5.32 0.18 5.04 log k = 5.55 2.810 5.43 0.235 4.84 2.880 5.53 0.29 4.65 2.980 5.65 0.32 4.43 3.077 5.76 0.32 4.24 3.180 5.85 0.39 4.08 3.318 5.96 0.43 3.90 3.410 6.02 0.43 3.80 3.907 6.29 0.56 3.40 4.256 6.43 0.71 3.23 In the total initial volume of 98.7 ml., A = 5. Ob x 10-5, C = 3.99 ,-3 10 ", = 0.547 x 10 -3". Titrated vdth 0.2007 N NaOH at 35UC. 50 volume $ dioxane. Table 46. Titration of methylene dianthranilic acid and nickel with = 1.094 x 10-3.

111. base pR P^Gorr. n

2.643 4.89 0 .1 0 5.89 2.840 5.27 0.21 5.17 2.910 5.37 0.235 4.97 log k = 3.92 2.980 5.46 0.27 4.81 3.082 5.58 0.30 4.56 3.153 5.62 0.36 4.52 3.260 5.72 0.395 4.35 3.368 5.80 0.44 4.21 3.480 5.88 0.48 4.08 3.685 6.01 0.49 3.86 3.980 6.17 0.56 3.63 4.380 6.34 0.825 3.32 4.925 6.60 0.97 3.14 -3 In the total initial volume of 98.7 m l ., A = 5-06 x 10 y-3 -3 10 , C.. = 1.094 x 10 Titrated with 0.2007 N NaOH at 35 C. n 50 volume fo dioxane. ot-

o.e

0.6

0.4

0.2

0.0 2 8 3.2 3.6 4.0 4.4 4.8 5.2 5.6 6.0

FIGURE 24. n-pR CURVE FOR METHYLENE DIANTHRANILIC ACID AND NICKEL FROM TABLE 46 . VJlVX> Table 47. Titration of methylene dianthranilic acid and copper with CM = 0.35 x 10-5.

Ml. base pR pHCorr. n 2.342 3.48 0.02 8.69 2.420 3.62 0.13 8.41 2.480 3.79 0.18 8.08 log k = 7.03 2.584 4.11 0.36 7.45 2.618 4.24 0.46 7.19

In the total initial volume of 98.7 ml., A = 5.06 x 1 D-3, CR = 3.88 x 10~3, C = 0.35 x 10'3. Titrated with 0 .2007 N UaOH 50 volume '$>

with CM = 0.70 x 10-3.

Ml. base pR pHCorr. n

2.325 3.32 0.18 9.05 2.455 3.50 0.19 8.70 2.620 3.79 0.31 8.14 log k = 2.757 4.08 0.45 7.57 2.855 4.33 0.54 7.08

In the total initial volume of 98.7 ml., A = 5.06 x 10~3 = 10"3 , Cv = 0.,70 x 10"3 . Titrated with 0.2007 M RaOIi at 35°C. M ^ . 50 volume 7° dioxane. 97

Table 49. Titration of methylene dianthranilic acid and copper with = 1.40 x 10-3.

Ml. base pR ■^Corr. n

2.026 2.98 0.08 9.59 2.350 3.19 0.14 9.18 2.520 3.33 0.19 8.91 log k = 7.65 2.700 3.51 0.28 8.56 2.820 3.62 0.33 8.35 2.940 3.78 0.385 8.04 3.060 3.89 0.465 7.83 3.190 3.94 0.556 7.74 -3 In the total initial volume of 98.7 ml., A = 5.06 x 10' , CR = 4.95 x 10-3, CH = 1.40 x 10~3 . Titrated with 0.2007 N NaOH at 35°C. 50 volume Jo dioxane. Table 50. Titration of methylene diantnranilic acid and zinc with Cjv. = 0.57 x 10-3.

Ml. base pR pHCorr. n

2.520 4.67 0.00 6.32 2.650 5.12 0.120 5.44 2.780 5.41 0.20 4.89 log k = 5.82 2.850 5.50 0.22 4.73 2.960 5.62 0.30 4.51 3.090 5.78 0.365 4.23 3.270 5.92 0.44 3.98 3.520 6.08 0.54 3.73 3.760 6.22 0.61 3.52 4.115 6.40 0.67 3.28 , A = 5.06 x 10'-3 In the total initial volume of 98.7 ml. 1 °R = 5 *84 -3

V - 0 „ II o o H .57 x 10 . Titrated with 0.2007 if NaOH a

50 volume jo dioxane.

Table 51. Titration of methylene dianthranilic i with CT,. M = 1.14 x IQ”5.

M l . base p R pHCorr. n 2.580 4.72 0.05 6.22 2.670 5.01 0.10 5.66 2.780 5.22 0.165 5.24 log k = 3.91 2.880 5.37 0.20 4.98 2.980 5.48 0.245 4.78 3.090 5.59 0.31 4.58 3.180 5.69 0.33 4.40 3.300 5.77 0.41 4.27 3-390 5.83 0.42 4.17 3.540 5.94 0.48 3.98 3.75 6.07 0.543 3.78 3.960 6.18 0.62 3.62 -3^ the total initial volume of 98.7 ml., A = 5.06 x 10 CR = 3.87 -°n 1 0 .14 x 10 Titrat ed with 0 .2007 N NaOH a' volume 'jo idioxane. Table 52. Titration of methylene dianthranilic acid and cadmium with = 1.05 x 10“3.

Ml. base pH pR Gorr. n 2.468 4.06 0.05 7.42 2.576 4.49 0.09 6.57 2.676 4.76 0.15 6.04 2.778 4.98 0.22 5.61 2.918 5.19 0.30 5.21 3.098 5.40 0.40 4.82 3.418 5.67 0.54 4.33 3.696 5.85 0.65 4.02 4.018 6.03 0.72 3.73 4.355 6.18 0.81 3.50 4.832 6.38 0.86 3.23 -5 In the total initial volume of 98.7 ml., A = 5.06 x 10 , CR = 5.07 7 .7 it 10 , CM = 1.05 x 10 . Titrated with 0.2007 N NaOIi at 35°C. 50 volume $ dioxane. Table 53. Titration of methylene dianthranilic acid and cadmium with C,„ = 2.10 x 10~3. M

tl. base pR pHCorr. n 2.492 4.02 0.04 7.51 2.598 4.36 0.06 6.83 2:734 4:65 Oil! 6:27 log k = 4.32 2.914 4.93 0.17 5.73 3.094 5.13 0.25 5.35 3.412 5.41 0.35 4.84 3.657 5.57 0.39 4.54 3.909 5.73 0.53 4.28 4.250 5.92 0.74 4.01 4.794 6.07 0.79 3.78 5.054 6.28 0.76 3.45

the total initial volume of 98.7 ml., A = 5.06 x 10' C = 4.99 'Z 'Z ** 10*0 , CM = 2.10 x 10"°. Titrated with 0.2007 N NaOH at 35°C.

50 volume $ > dioxane. 100 Table 54. Titration of M 1 trimetliylene dianthranilic acid

in 50 volume fo dioxane.

pHCorr.

0.000 2.57 0.000 0.650 2.48 0.262 1 .0 9 0 2.60 0.440 1.490 2.75 0.602 2.010 5.08 0.849 2.290 5.48 0.925 2.410 3.99 0.974 2.432 4.25 0.985 2.470 4.57 0.998 2.493 4.82 1.008 2.600 5.29 1.055 2.740 5.60 1.116 5.100 5.97 1.275 3.400 6.19 1.406 3.770 6.58 1.570 4.010 6.47 1.675 4.268 6.54 1.789 4.520 6.75 1.9 0 0 4.850 6.88 2.055 5.170 7.02 2.185 5.510 7.14 2.555 5.810 7.28 2.465 6.120 7.44 2.605 6 .5 0 0 7.74 2.77 6.800 8.16 2.90 6.900 8.43 2.945 7.010 9.18 2.99 7.057 9.73 5.01 7.070 10.20 5.02 7.100 10.47 5.055 7.200 10.88 5.08 Table 54 Continued

C1 = 6.50 C 2 = 7.32

Convergence correction is 0.15.

pkaX = 6.45 pka2 - 7.17

From Schwarzenbach's graphical method: pkal = 6.45 ± 0.07 pka2 = 7.17 + 0.04

5.00 x 10 ^ moles of HNO and 4.58 i 10 ^ moles of diA.A. Total 5 initial volume, 98.7 ml. Equal volumes of dioxane and 0.2007 N NaOH added. 35°C. 0.0 0.5 1.0 1.5 Z 0 2.5 3.0 a 102 FIGURE 25. pH-a CURVE FOR N, N1 - TRIMETHYLENE DIANTHRANILIC ACID FROM TABLE 54. Table 55 * Titration of M 1 trimethylene dianthranilic acid

in 50 volume fo dioxane at ionic strength 0.1 (KWO^).

^Corr. 0.000 2.52 0.000 0.550 2.45 0.214 1.000 2.55 0.405 1.500 2.74 ' 0.607 2.000 5.09 0.810 2.500 5.58 0.951 2.592 4.01 0.969 2.497 4.62 1.007 2.590 4.95 1.051 2.800 5.54 1.140 5.118 5.64 1.275 5.420 5.84 1.404 5.710 5.99 1.527 4.010 6.12 1.654 4.555 6.25 1.791 4.640 6.58 1.922 4.900 6.48 2.052 5.200 6.59 2.160 5.500 6.71 2.288 5.800 6 .84 2.415 6.120 7.01 2.550 6.465 7.24 2.698 6.790 7.54 2.855 7.020 8.O4 2.9 5 2 7.120 8.62 2.976 7.220 10.04 5.020 7.400 10.80 5.09 pkal = 6,10 pka2 = 4*75 x 10 ^ moles of diA.A. and 5.00 x 10-4 moles HN0_ and 9.40 x -5 5 10 moles KNO^. Total initial volume 98.7 ml. Equal volumes of dioxane and 0.2007 N ifaOH. 55°C. Table 56. Titration of I W trimethylene dianthranilic acid

and cobalt with Ci, = 0.60 x 10”5.

h i . base n pR ^ C o r r .

2.300 3.38 0.00 9.21 2.376 3.60 0.05 8.77 2.478 4.10 0.07 7.73 log k = 5.06 2.578 4.76 0.11 6.47 2.668 5.07 0.21 5.85 2.765 5.22 0.335 5.58 2.900 5.41 0.405 5.22 3.000 5.51 0.53 5.04 3.122 5.63 0.64 4.81 3.295 5.78 0.765 4.55 3.490 5.92 0.90 4.31 In the total initial volume of 98.7 ml ., A = 5.06 x 10■ 3 , CR = 4.70 -3 10"5 , C,. = 0..60 x 10 . Equal volumes off dioxane and 0.200< vrere added. 50 volume dioxane. 35°C.

Table 57• Titration of I^N1 trimethylene dianthranilic acid

and cobalt with Cy. = 1.20 x 10 3 .

hi. base pH,, n pR Corr. ^ . 2.310 3.39 0.04 9.19 2.415 3.32 0.03 8.33 2.500 4.27 0.05 7.45 log k = 4.93 2.592 4.77 0.10 6.45 2.693 5.01 0.15 5.99 2.815 5.16 0.20 5.70 2.938 5.28 0.30 5,48 3.245 5.55 0.45 4.99 3.418 5.65 0.575 4.82 3.630 5.78 0.69 4.60 3.957 5.98 0.835 4.26 In the total initial volume of 58.7 ml.. A = 5.06 x 10 3, C„ - 4.69 -3 -3 “ 10 , 0 = 1.20 x 10 . Equal volumes of' dioxane and 0.2001 N NaOH were added. 50 volume /j dioxane. 35 C. 105 Table 58. Titration, of MM1 trimethylene dianthranilic acid -•5 and cobalt with = 0,60 x 10 .

Ml. base pR pHCorr. n 2.295 3.48 0.00 9.00 2.422 3.82 0.07 8.33 2.543 4.72 0.09 6.54 2.650 5.08 0.16 5.83 2.790 5.32 0.28 5.37 2.910 5.44 0.405 5.15 3.022 5.58 0.515 4.89 3.160 5.71 0.62 4.66 3.303 5.82 0.695 4.46 3.503 5.93 0.86 4.28 3.800 6.15 0.92 3.92

In the total initial volume of 98.7 ml., A = 5.06 x lO-'’, Cp = 4.78 x -3 10 , Cj;. = 0.60, and enough was present to make the initial ionic strength = 8.6 x 10 Equal volumes of dioxane and 0.2001 d iSaOH were added. 5^ volume fo dioxane. 35°C. 106

Table 59. Titration of M 1 trimethylene dianthranilic acid and

nickel with CM = 0.547 x 10-3 •

Ml. base pR pHCorr. n

2.300 3.42 0.04 9.13 2.402 3-75 0.10 8.48 2.550 4.62 0.135 6.75 log k = 5.47 2.640 4.90 0.21 6.20 2.720 5.08 0.35 5.85 2.860 5.28 0.505 5.47 3.000 5.44 0.64 5.17 3.213 5.67 0.80 4.75 3.404 5.84 0.92 4.45 3.600 5.99 1.04 4.19 3.890 6.22 1.00 3.82

In the total initial volume of 98.7 ml., A = 5.06 x 10"3, C = 4.67 x 10 3, = 0.547 X 10 5 . Equal volumes of dioxane and 0.2001 N NaOH were added. 50 volume fo dioxane. 35°C.

Table 60. Titration of N,H‘ trimethylene dianthranilic acid and nickel with = 1.094 x 10~3.

Ml. base pH„ — pR * Corr. n * 2.305 3.43 0.00 9.09 2.413 3.77 0.00 8.42 2.515 4.33 0 .0 3 7.32 log k = 5.39 2.655 4.81 0.115 6.37 2.750 4.98 0.20 6.05 2.925 5.13 0.34 5.77 3.075 5.27 0.44 5.51 3.275 5.43 0.58 5.22 3.550 5.61 0.765 4.90 3.800 5.81 0.90 4.55 4.040 5.98 0.99 4.27 4.325 6.19 0.97 3.93 _3 In the total initial volume of 98.7 ml., A = 5.06 x 10 , C = 4.71 x -3 -3 10 , Cv = 1.094 x 10 . Equal volumes of dioxane and 0.2001 N NaOH ^ > 0 were added. 50 volume jo dioxane. 35 C. Table 61. Titration of M 1 trimethylene dianthranilic acid and copper with CM = 0 .7 0 x 10-3.

M l . base - pR ^ Corr. n * ..2.130 3 .2 2 0.00 9.48 2.305 3.41 0.06 9 .0 2 2.405 3.54 0 .1 2 8.85 log k = 8.03 2.515 3.68 0.21 8.58 2.612 3.80 0.315 8.35 2.805 4.02 0.56 7.93 2.990 4.33 0.79 7.32 3.130 4.90 0 .8 8 6 .2 0 3.195 5 .2 2 0 .8 8 5.58 In the total initial volume of 98.7 ml., A = 5.06 x 10"3 , C = -3 5 .0 0 x 10”5 , CM = 0 .7 0 x 10' . Adding equal volumes of dioxane and 0.2001 N MaOH. 50 volume f<> dioxane. 35°C.

Table 62. Titration of N.N' trimethylene dianthranilic acid and copper with C = I.4O x 10-3. M

Ml. base pR pHCorr. n

1.905 2.97 0 .0 0 9.96 2.105 3.10 0.04 9.71 2.285 3.28 0.08 9.35 log k = 8.17 2.423 3.40 0.16 9.13 2.565 3.52 0.19 8.89 2.700 3.62 0.26 8.71 2.840 3.73 0.35 8 .5 0 2.935 3.81 0.40 8.34 3.095 3.91 0.515 8.16 3.235 4 .0 1 0.67 7.97 3.430 4.18 0.785 7 .6 6 3.640 4.40 0.87 7.24 3.820 4.89 0.95 6.28 3.985 5.48 0.97 5.14 4.095 5.70 0.955 4.72 4.215 5.90 0.93 4.36

In the total initial volume of 98.7 ml., A = 5.06 x 10 3, C_ = 5.20 -3 -3 10 , Cjj = 1.40 x 10 . Equal volumes of dioxane and 0.2001 N NaOH added. 50 volume dioxane. 35 C. 108 Table 63• Titration of M ' trimethylene dianthranilic acid and copper at ionic strength =: 0.1 with, C.r = 0.70 x 10-5. M

Ml. base pR pHCorr. n 2.088 5.14 0.00 8 .9 2 2.300 3.39 0.06 8.43 2.420 3.56 0.135 8.10 log k = 7.44 2.500 5.64 0.21 7.94 2.620 3.80 0.345 7.63 2.720 3-92 0.555 7.40 2.890 4.13 0.635 6.99 3 .0 0 0 4.29 0.79 6.68 3.100 4.54 0.86 6.20 3.220 4.85 0.915 5.60 3.375 5.24 0.895 4.85 3.525 5.43 0.81 3.70 In the total initial volume of 98.7 ml., A = 5.06 x 1Q“3 , 0 = 4.97 x _3 R 10 3 , cM = 0 .7 0x 10 , and enough KNO^ was1 present to make the ionic strength = 0.10. Equal volumes of dioxane and 0.2001 N NaOH were added. 50 volume yi> dioxane . 35°C. Table 6 4. Titration of iJ.if' trimethylene dianthranilic acid and copper at ionic strength =: 0.1 with CM = 1.40 x 10-3.

Ml. base pR pHCorr. n 1.890 2.96 0.00 9.22 2.080 3.11 0.01 8.97 2.205 3.23 0 .0 4 8.74 log k = 7.33 2.287 3.33 0.05 8.54 2.440 3.47 0.11 8.27 2.545 3.54 0.165 8.14 2.653 3.64 0.22 7.94 2.820 3.77 0.31 7.70 2.990 3.89 0.42 7.47 3.195 4.02 0.56 7.23 3.395 4.15 0.69 7.00 3.600 4.36 0.81 6.60 3.800 4.72 0.93 5.91 4.000 5.21 0.955 4.97 4.240 5.54 0.97 4.37 In the total initial volume of 98.7 ml., A = 5.06 x 10 3 , C„ = 5.11 x -3 -3 10 , = 1 .4 0 x 10 , and enough KNO^ was present to make the ionic strength = 0.10. Equal volumes of dioxane and 0.2001 N NaOH were added. 50 volume & dioxane. 35°C. Table 65. Titration of NN' trimethylene dianthranilic acid and zinc with CM = 0.57 x 10- 5.

Ml. base pH pR Corr. n 2.400 3.97 0.00 8.02 2.500 4.62 0.05 6.72 2.605 4.92 0.13 6.13 log k = 5.09 2.720 5.12 0 .3 0 5.75 2.884 5.38 0.43 5.26 3.080 5.60 0.60 4.85 3.365 5.88 0.80 4.35 5.68 6.12 0.755 3.94

In the total initial volume of 98.7 ml., A = 5 .06 x 10~3 , CR = 4.87 -3 -"5 10 , - 0.57 x 10 . Equ.v1 volumes of dioxane and 0.2001 N NaOH

were added. 50 volume fo dioxane. 35°C.

Table 66. Titration of N,N' trimethylene dianthranilic acid _ and zinc with Cr = 1.14 x 10

Ml. base pR ^ C O I T . n

2.402 3.68 0.03 8.62 2.517 4.16 0.08 7.67 2.610 4.57 0.12 6.86 log k = 5.43 2.718 4.83 0.185 6.36 2.920 4.97 0.42 6.10 3.040 5.22 0.42 5.62 3.208 5.37 0.53 5.34 3.380 5.48 0.645 5.15 3.590 5.66 0.75 4.83 3.800 5.82 0.84 4.55 4.008 5.95 0.955 4.34

l ,the total initial volume of 538.7 ml.* A = 5.06 x r 3 , C R = 4 . 5 9 10 , = 1.14 x 10 Equal volumes of dioxane and 0.2001 N NaOH were added. 50 volume c/a dioxane. 35°C. Table 67. Titration of N,N' trimethylene dianthranilic acid

and zinc with = 1.14 x 10 ,

Ml. base pH pR Corr. n

2.300 3.43 0.00 9.14 2.4 0 0 3.68 0.03 8.65 2.600 4.62 0.10 6.80 log k = 5.26 2.800 5.02 0.23 6.01 3.000 5.27 0.38 5.54 3.200 5.43 0.505 5.25 3.420 5.61 0.63 4.93 3.700 5.81 0.79 4.59 3.990 6.02 0.92 4.24 4.300 6.22 1.01 3.93 4.630 6.45 1.045 3.60

In the total initial volume 01 98.7 ml., A = 5.06 x r 3 , C = 4.36

10 , Cjj = 1.14 x 10 . Equal volumes of dioxane and 0.2001 N NaOH were added. 50 volume $ dioxane. 35°C. Table 68. Titration of NN' trimethylene dianthranilic acid

and cadmium with = 0.525 x 10- 3 .

Ml. base pR pHCorr. n

2.398 3.80 0.12 7.34 2.496 4.39 0.08 7.17 2.600 4.81 0.16 6.34 log k = 5.29 2.700 5.05 0.30 5.88 2.800 5.22 0.405 5.55 2.908 5.38 0.525 5.24 3.016 5.52 0.565 4.98 3.128 5.65 0.65 4.74 3.325 5.88 0.65 4.33 3.463 6.00 0.675 4.12 3.673 6.17 0.555 3.83

the total initial volume of 98.7 ml.> A = 5.06 x 10~3, C = 5.04 -3 -3 10 , = 0.525 x 10 „ Equal volumes of dioxane and 0.2001 N NaOH were added. 50 volume °fo dioxane. 35°C.

Table 69. Titration of N tN ‘ trimetliylene dianthranilic acid

and cadmium with = 1.05 x 10 .

Ml. base pR ^ C o r r n

2.216 3.35 0.00 9*25 2.565 4.60 0.10 6.77 2.888 5.10 0.34 5.80 log k = 5.28 3.133 5.37 0.485 5.30 3.340 5.55 0.61 4.97 3.682 5.86 0.75 4.42 3.963 6.06 0.83 4.09 4.123 6.19 0.81 3.87 4.303 6.29 0.35 3.72

In the total initial volume of 98.7 ml. , A = 5.06 x 0’ = 4.91 x 1 0 -3, cM = 1 .05 x 10 3 . Equal volumes of dioxane ar were added. 50 volume yo dioxane. 35°C • 112 Table 70. Titration of N-(2-aminoethy 1) anthranilic acid.

2HC1 in 50 volume L/o dioxane.

M l . base a ^ C o r r . 0.000 2.38 0.000 0.420 2.44 0.170 0.960 2.58 0.389 1.305 2.68 0.529 1.760 2 .9 0 0.721 1.990 3.08 0.806 2.225 3.34 0.903 2.320 3.58 0.940 2.432 3.90 0.985 2.535 4.27 1.027 2.640 4.50 1.070 2.7S5 4.73 1.129 3.000 5.00 1.216 3.205 5.19 1.300 3.410 5.32 1.380 3.598 5.48 1.457 3.680 5.53 1.490 3.790 5.62 1.536 3.920 5.72 1.590 4.380 6.08 1.773 4.780 6.78 1.937 4.077 7.28 1.978 4.905 7.52 1.990 4.942 7.74 2.001 5.002 8.10 2.025 5.440 6.88 2.200 5.986 9.32 2.425 6.080 9.40 2.460 6.184 9.47 2.504 6.290 9.53 2.545 Table 70 Continued.

6.763 9.88 2.743 7.160 10.29 2.900 7.360 10.71 2.985 7.455 10.98 3.02 7.805 11.72 3.165 pka]_ = 5.54 pka2 = 9.45

-4 4.94 x 10 moles of A.A. 0.00 moles HN0_. Total initial volume 3 98.7 ml. Equal volumes of dioxane and 0.2007 H NaOH added. 35 C 12.0

10.0

8.0 pH 6.0

4 0

2.0

0.0 0.5 1.0 2.0 2.51.5 3.0 a

FIGURE 26. p H -a CURVES FOR N - (2 -AMINOETHYL) ANTHRANILIC ACID DlHYDROCHLORIDE £ FROM TABLES 70 AND 76 115 Table 71. Titration of N-l2-aminoethyl)-anthranilic acid and cobalt with Cw = 0.60 x 10-2.

Ml. base pH Corr. n pH

2.995 5.00 0.00 7.43 3.143 5.11 0.04 7.24 3.327 5.27 0.02 6.97 6.03 3.568 5.42 0.11 6.73 3.843 5.60 0.13 6.46 (log kik2)/2=5 4,093 5.73 0.31 6.29 4.403 5.93 0.475 6.03 5.00 C2 = 4.700 6.13 0.75 5.80 5.000 6.42 1.05 5.49 5.300 6.90 1.50 5.00 5.493 7.83 1.74 4.08 In the total initial volume of 98.7 ml., A = 0.00 x 10 , CL. = 5.00 x -3 -3 10 , Cy = 0.60 x 10 . Equal volumes of dioxane and 0.2001 N NaOH were added. 50 volume c/o dioxane. 35°C.

Table 72. Titration of N-(2-aminoethyl)-anthranilic acid and cobalt with C„, = 1.20 x 10-3. M

Ml. base pR pHCorr. n

2.635 4.52 0.02 8.33 2.735 4.68 0 .0 4 8.03 2.835 4.81 0.05 7.79 C1 = 6.20 2.975 4.94 0.07 7.55 3.215 5.12 0.12 7.24 (log k1k_)/2=5.76 3.430 5.28 0.16 6.98 3.895 5.52 0.33 6.62 C2 = 5.25 3.615 5.38 0.23 6.83 4.195 5.71 0.40 6.35 4.500 5.88 0.525 6.14 4.800 6.07 0.71 5.93 5.100 6.23 0.995 5.77 5.400 6.48 1.25 5.53 5.800 7.03 1.68 5.02

the total initial volume of 98.7 ml., A = 0.00 x 10''~3 , CR = 4.90 x -3 -3 10 , C,4j = 1.20 x 10 . Equal volumes of dioxane and 0.2001 N NaOH were added. 50 volume c/o dioxane. 35°C. 116 Table 73. Titration of N-(2 -aminoethyl)-anthranilic acid and nickel with CM = 0.547 x 10-3.

Ml. base pR ^C o r r . n

2.790 4*60 0.155 8.17 2.935 4.72 0.33 7.95 3.085 4.82 0.485 7.78 C. = 7.77 1 3.195 4.89 0.56 7.65 3.415 5.02 0.74 7.43 (log k k )/2: ± d 3.600 5.11 1.02 7.29 3.780 5.21 0.96 7.12 C0 = 6.62 4.015 5.37 1 .3 0 6.87 4.255 5.51 1.465 6.67 4.450 5.63 1.59 6.50 4.675 5.82 1.62 6.24 4.885 6.02 1.65 5.98 5.080 6; 30 1.65 5.65

In the total initial volume of 98.7 ml., A = 0.00 x 10'"5, CR = 5.00 -JX 10 , = 0.547 x 10 . Equal volumes of dioxane and 0.2001 N NaOH were added. 50 volume °/o dioxane. 35°C.

Table 74. Titration of N-(2-aminoethyl)-anthranilic acid and nickel with C^, = 1.094 x 10-3.

Ml. base PHCorr. n pR

2.310 4.00 0.02 9.36 2.413 4.21 0.07 8.95 2.515 4.33 0.125 8.73 C ± = 7.96 2.855 4.58 0.35 8.27 2.965 4.71 0.39 8.03 (log kxk2 )/2=7.44 3.215 4.82 0.585 7.85 3.415 4.92 0.73 7.69 C2 = 7.00 3.625 5.00 0.87 7.57 3.870 5.11 1.045 7.40 4.140 5.22 1.25 7.25 4.400 5.33 1.435 7.09 4.720 5.53 1.62 6.81 4.930 5.68 1.725 6.61 5.235 5.94 1.92 6.30 5.505 6.43 2.01 5.73 the total initial volume of 93.7 ml., A = 0.00 x 10'"5, Cp = 4.62 x -3 -3 10 , Cjj = 1.094 x 10 . Equal volumes of dioxane and 0.2001 N NaOH were added. 50 volume dioxane. 35 C. 117 Table 75. Titration of N-(2-aminoethy1)-anthranilie acid and copper with = 0.70 x 10“3.

Ml. base pR pHCorr. n

1.990 3.02 0.02 11.27 2.130 5.11 0.06 11.09 2.290 3.22 0.18 10.88 log = 10.37 2.415 3.30 0.21 10.73 2.600 3.44 0.43 10.46 (log 3^)72=5.85 2.750 3.54 0.59 10.28 2.990 3.82 0.79 9.73 log k 2 = 4.83 3.200 4.38 0.88 8.64 3.570 4.98 0 .9 0 ,7.52 3.800 5.22 0.91 ,7*11 4.010 5.40 0.895 6.82 4.190 5.53 0.93 6.62 4.520 5.82 0.935 6.21 4.790 6.05 0.99 5.92 5.000 6.27 1.07 5.67 5.190 6.57 1.23 5.34 5.410 7.03 1.46 4.88 5.845 8.69 1.75 3.30

In the total initial volume of 98.7 ml., A = 0.00 x 10 '3, CR = 5.02 x 10 = 0.70 x 10 3. Equal volumes of dioxane and I1.2001 N NaOH were added. 50 volume c/° dioxane. 35°0. 118 Table 76. Titration of N-(2-aminoethyl)-anthranilic acid and

copper with = 1.40 x 1 0 ~ 5 .

HI. base pR ■^Corr. n 2 .005 3.00 0.10 11.34 2.120 3.07 0.135 11.21 2.210 3.11 0.18 11.14 2.360 3.19 0.225 10.98 log = 10.53 2.465 3.23 0.285 10.91 2.645 3.32 0.37 10.74 (log k1k2)/2=7.95 2.780 3.40 0.44 10.60 3.000 3.50 0.57 10.42 log k2 = 4.98 3.170 3.60 0.66 10.24 3.405 3.76 0.75 9.93 3.705 4.11 0.82 9.26 3.900 4.60 0.985 8.34 4.005 4.81 1.00 7.95 4.150 5.02 1.02 7.57 4.310 5.21 1.03 7.25 4.505 5.42 1.035 6.91 4.720 5.63 1.055 6.60 4.930 5.83 1.07 6.32 5.175 6.11 1.12 5.98 5.385 6.37 1.23 5.70 5.705 6.88 1.30 5.16 5.915 7.33 1.68 4.79 6.020 7.66 1.82 4.50 6.125 8.08 1.94 4.12

In the total initial volume of 98.7 ml., A = 0.00 x 10 , CR = 4.82 x 10"3 , C- = 1.40 x 10“3 Equal volumes of dioxane and 0.2001 N iTaOH iu were added. 50 volume °/° dioxane. 35^0. 119 Table 77. Titration of N-(2-aminoethyl)-anthranilic acid and zinc with = 0.57 x 10“3.

Ml. base pR ■^Corr. n

4.330 5.89 0.00 6.04 4.540 6.02 0 .1 9 5.89 4.800 6.28 0.155 5.57 C ± = 5.37 5 .0 0 0 6 .5 0 0.425 5.34 5.205 6.78 0.755 5.06 (log k k )/2=4.73 5.328 7.05 0.93 4.79 5.430 7.32 1.11 4.53 C2 = 4.08 5.538 7.63 1.44 4.23 5.635 8.03 1.60 3.85 In the total initial volume of 98.7 ml., A = 0.00 x 10 , CD = 5.20 x 10 , = 0.57 x 10 . Equal volumes of dioxane and 0.2001 N NaOH were added. 50 volume 7 dioxane. 35 C.

Table 78. Titration of N-(2-aminoethyl)-anthranilic acid and zinc with C„. = 1.14 x 10 M

Ml. base pR ^Corr. n 3.120 5.10 0.03 7.26 3.320 5.26 0.05 6.99 3.530 5.39 0.10 6.79 C1 = 5.54 3.795 5.58 0.11 6 .5 0 4.100 5.77 0.17 6.24 (log ^ j ^ . O l 4.300 5.91 0.19 6.06 4.600 6.13 0.335 5.80 c2 = 4.50 4.910 6.40 0.52 5.51 5.110 6.62 0.715 5.29 5.410 7.00 1.08 4.94 5.715 7.50 1.50 4.50 5.820 7.73 1.665 4.30 5.915 8.01 1.77 4.04 In the total initial volume of 98.7 ml., A = 0.00 x 10”^, C = 4.95 x -3 -3 10 , Cjj = 1.14 x 10 . Equal volumes of dioxane and 0.2001 N NaOH were added. 50 volume 7 dioxane. 35°C. 120 Table 79. Titration of N-(2-aminoethyl)-anthranilic acid and cadmium with CM = 0.525 x 10-3.

Ml. base pR ^Corr. n

4.990 7.61 0 .0 0 4.18 5.070 7.91 0 .1 0 3.90 5.160 8.13 0.23 3.69 C ' = 3.44 5.310 8.38 0.485 3.47 5.420 8 .5 6 0.635 3.31 (log k1k2 )/2= 2.92 5.507 8 .6 8 0 .6 8 3 .2 1 5.645 8.82 0.85 3.10 1C2 = 2.72 5.850 9.0 2 0.9 6 2.96 6.010 9.17 0.94 2.85 6.284 9.34 1.35 2.77 6.610 9.58 1.62 2.67

the total initial volume of 98.7 ml., A = 0 .0 0 x 10)"3‘ , cw = 5.06 x -3 -3 10 , = 0.525 x 10 . Equal volumes of dioxane and 0.2001 N NaOH were added. 50 volume 70 dioxane. 35°C.

Table 80. Titration of H-(2 -aminoethy1)-antfaranilie acid and cadmium with = 1.05 x 10“3.

El. base pH,., — pR ^ Corr. n ^ 4.630 6.62 0 .0 0 5.19 4.850 7 .0 2 0.03 4.79 4.990 7.43 0.19 4.39 C1J. = 5.135 7.72 0 .3 8 4.1 2 5.260 7.98 0.57 3.89 (log 5.470 8.28 0.865 3.64 5.840 8.69 1.345 3.33 C? = 6.195 9.03 1.64 3.10 6.640 9.38 2.22 2.90

the total initial volume of 98.7 ml., A = 0.00 x 10"3 , C. -■5 -'3 R ~ 10 , = 1.05 x 10 . Equal volumes of dioxane and 0.2001 N NaOH were added. 50 volume jo dioxane. 35°C. 1 2 1 Table 81. Titration of 2-(aminomethyl) benzoic acid in 50

volume fo dioxane.

Ml. base a pHCorr. 0.000 2.36 0.000 0.500 2.43 0.202 1.023 2.57 0.414 1.510 2.72 0.610 2.020 2.95 0.816 2.410 3.22 0.975 2.520 3.31 1.018 3.040 3.69 1.230 3.540 4.03 1.434 3.700 4.16 1.499 3.800 4.22 1.540 4.020 4.37 1.630 4.520 4.88 1.834 4.705 5.22 1.909 4.810 5.65 1.950 4.875 6.71 1.978 4.910 7.63 1.992 4.970 8.51 2.016 5.045 8.92 2.048 5.240 9.40 2.127 5.500 9.67 2.233 6.000 10.04 2.436 b.120 10.12 2.485 6.220 10.22 2.526 7.000 10.68 2.843 7.320 10.96 2.97 7.400 11.06 3.005 7.510 11.09 3.05 8 .0 4 0 11.53 3.27

Pkal = 4.17 P*a2 = 10.16 Table 81 Continued.

—4 —4 5.00 x 10 moles HN0„ and 4.94 x 10 moles B.A. Total initial b volume, 98.7 ml. Titrated with 0.2007 N NaOH at 35 C. pH

0.0 0.5 1.0 1.5 2.0 2 5 3.0

a 123

FIGURE 27. p H -a CURVE FOR 2 - (AMINOETHYL) - BENZOIC ACID FROM TABLE 81. 124 Table 82. Titration of 2-(aminomethyl) benzoic acid and cobalt with CL = 0.60 x 10 M

HI . b a s e pR ^Corr. n 2,320 4.93 0.00 7.62 2.440 ; 5.52 0.00 6.96 2.510 6.04 0.05 6.4 2 C = 4.65 i 2.570 7.12 0.07 5.34 2.640 7.64 0.31 4.83 (log k k )/2=4.20 1 d 2.715 7.92 0.495 4.56 2.780 8.11 0.72 4.39 0o = 3.98 d 2.880 8.32 1.01 4.20 3.025 8.63 1.58 3.93 3.140 8.89 1.63 3.68 3.266 9.20 1.73 3.40 3.400 9.40 1.87 3.24

In the total. initial volume> of 98.7 ml., A = 0 .00, C = 5.19 x 10“5 ,

CL = 0.60 x 10 . Titrated with 0.2007 N NaOH at 35°C2. 50 volume r/o H dioxane.

Table 83. Titration of 2-(aininome;thyl)-benzoic acid and cobalt with CM = 1.20 x 10 .

HI. base pR ^Corr. n

4.805 5.87 0.03 6.64 4.910 7.12 0.11 5.39 5.010 7.63 0.32 4.90 C. - 4.65 X 5.110 7.87 0.46 4.68 5.210 8.01 0.62 4.57 (log k1k2 )/2=4.36 5.530 8.35 1.12 4.30 5.810 8.47 1.60 4.26 C_ = 4.25 d 6.105 9.15 2.04 3.69 _3 In the total initial volume of 98.7 ml., A = 5.02 x 10 , = 4*84 x 1CT5, CL = 1.20 x 10-5. Titrated with 0.2007 N NaOH at 35°C. 50 rl volume °/o dioxane* 125 Table 84. Titration of 2-(aminomethyl) benzoic acid and nickel with = 1 .0 9 4 :x 10-3.

Ml. base pR ^Corr. n 2.000 5.08 0.02 7.48 2.290 6.29 0.10 6.23 2.388 6.89 0.27 5.65 C. = 5.28 X 2.488 7.22 0.45 5.34 2.630 7.58 0.705 5.01 (log k k )/2=4.i 1 £- 2.793 7.97 1.00 4.66 2.932 8.23 1.23 4.44 C- = 4.14

. the total initial volume of 98.7 ml., A = 0.00, C = 4.58 x 10"5 , = 1.093 x 10 . Titrated with 0.2007 N NaOH at 35°C. 50 volume dioxane.

Table 85. Titration of 2-(aminome thyl)-benzoic acid and nickel with CH = 0.547 x 10“3.

Ml. base pR ^Corr. n 2.1 9 0 4.97 0.02 7.55 2 .4 0 0 5.38 0.06 7.10 2.500 5.82 0.06 6.65 C. = 5.28 X 2.570 6.43 0.06 6.03 2.660 7.00 0.225 5.47 (log k k )/2=4.i X c. 2.730 7.37 0.675 5.12 2.775 7.67 0.86 4.83 G„ = 4.10

Ml. base pR H^Corr. n 1.845 4.52 0.39 8.14 2.131 4.76 0.51 7.85 2.341 4.99 0.645 7.59 C = 7.87 2.535 • 5.32 0.76 7.24 2.745 5.82 1.07 6.75 (log ^ 2 )72=6 .8 7 2.857 6.15 1.335 6.43 2.925 6.4 2 1.545 6.17 C2 = 6.20 3.029 6.89 1.84 5.73 3.105 7.47 1.99 5.16 3.170 8.42 2 .12 4.59 3.245 9 .0 0 2 .1 0 3.67 3.312 9.28 2.02 3.40 ,-3 In the total initial volume A = 0.00, C. of 98 .7 ml., R CM = 0.7° x 10-^. Titrated with 0.2007 W NaOH at 35°C. 50 volume °/o dioxane. Table 87• Titration of 2-(aminomethyl)-benzoic acid and copper with = 1.40 x 10-3.

Ml. base pR PH,Corr. n

4.460 4.67 0.18 7.96 4.800 4.96 0.29 7.63 5.230 5.44 O .64 7.16 7.35 °1 = 5.330 5.51 0.75 7.00 5.465 5.81 0.885 6.82 (log ^ 2 )/2=S .67 5.680 6.15 1.195 6.52 O ii 5.890 6.58 1.32 6.12 CM 6.00 6.090 7.12 1.755 5.67 6.230 8.00 1.925 4.83 6.370 9.17 2.00 3.74

In the total initial volume of 98.7 ml., A = 5.02 x 10 = 4.95 x 10“5 c„ = 1.40 x 10"5 Titrated with 0.2007 N NaOH at 35°C. 50 ’ h volume fo dioxane. 2 0

0.8

0 .4

Q0 4 .4 4 8 5 .2 5 .6 6.0 6 .4 6.8 7 .2 7 6 8.0

pR 127

FIGURE 28. ft-pR CURVE FOR 2 - (AMINOETHYL) - BENZOIC ACID AND COPPER FROM TABLE 87. 128 Table 88. Titration of 2-(aminomethyl) benzoic acid and zinc with CM = 0.57 x 10-3.

Ml. base pR pHCorr. h 2.360 5.44 0.00 7.04 2.440 5.78 0.00 6.69 2.540 6.59 0.09 5.88 C, = 5.66 X 2.578 6.74 0.235 5.73 2.650 6.90 0.47 5.59 (log k^kg)/^.- 2.740 7.01 0.775 5.49 2.850 7.13 1.155 5.39 C_ = 5.24 C. 2.950 7.33 1.535 5.21 3.060 7.95 1.84 4.61 3.130 8.70 1.91 3.88 3.167 8.90 1.92 3.69

In the total initial volume! of 98.7 ml., A = 0.00 , CR = 5.14 X 10"3 CM = 0.57 x 10 . Titrated. with 0.2007 N NaOH at 35 °C. 50 volume ^ dioxane.

Table 89. Titration of 2-(aminome thyl)-benzoic acid and zinc ■with CM = 1.14 x 10-3. M

Ml. base pR ^Corr. n

2.010 4.82 0.00 7.73 2.373 5.68 0.00 6.80 2.480 6.33 0.04 6.14 C n = 5.73 X 2.580 6.69 0.20 5.80 2.680 6.77 0.36 5.74 (log k1k2 )/2=5.< 2.874 6.84 0.715 5.71 3.183 7.03 1.26 5.59 C, = 5.52 3.500 7.54 1.81 5.16 3.700 9.08 1.965 3.68 3.800 9.33 2.02 3.47 3.940 9.55 2.11 3.30

In the total initial volume of 98.7 ml., A = 0.00, C = 5.04 x 10 , -5 o C = 1.14 x 10 . Titrated with 0.2007 N NaOH at 35 C. 50 volume jo dioxane. 12 Table 90. Titration of 2-(aminomethyl) benzoic acid and cadmium with CM = 0.525 x 10-3.

M l . base pR pHCorr. n

2.430 6.78 0.00 5.69 2.490 7.70 0.06 4.78 2.522 7.92 0.20 4.57 C = 4.13 2.590 8.23 0.40 4.27 X 2.650 8.45 0.56 4.07 (log k k )/2=3.70 2.570 8.65 0.86 3.88 1 d 2.830 8.88 0.98 3.67 C = (3.10) 2.930 9.08 1.14 3.49 * 3.040 9.23 1.32 3.36 3.150 9.41 1.38 3.21

In the total. initial volume of 98.7 ml., A = 0.00, C„ = 5.01 x TO-5, CM = 0.525 2: 10 3. Titrated with 0.2007 N IfeOH at 35°C. 50 volume fo dioxane.

Table 91. Titration of 2-(aminomethy1) benzoic acid and 3 ...... cadmium with CM = 1.05 x 10" •

Ml. base ^ C o r r . n pR 2.460 5.80 0.00 6.66 2.620 7.69 0.08 4.77 2.780 8.13 0.38 4.36 C = 4.26 2.985 8.45 0.75 4 *09 , 3.200 8.75 l.Ob 3.83 (log k k )/2=3.86 3.400 9.03 1.36 3.60 1 * 3.604 9.33 1.55 3.35 C = 3.44 -3 In the total initial volume of 98-7 ©1., A = 0.00, C = 5.21 x 10 , it C_T = 1.05 x lO-3, Titrated with 0.2007 N NaOH at 35°C, 50 volume M dioxane. 130

Table 9 2 . Titration of 2-(aminomethyl) benzoic acid in 30 volume $ dioxane at ionic strength 0.1 (KHP^)

Ml. base pHCorr. a 0.000 3.22 0.000 0.245 3.42 0.100 0.485 3.61 0.187 0.765 3.84 0.312 1.090 4-04 0.445 1.230 4-14 0.501 1.330 4.22 0.542 1.650 4.45 0.672 2.050 4.84 0.836 2.250 5.24 0.917 2.358 5.69 0.961 2.408 6.56 0.983 2.458 7.42 1.002 2.490 8.02 1.014 2.530 8.35 1.032 2.652 8.84 1.081 2.935 9.35 1.197 3.530 9.88 1.439 3.630 9.94 1.479 3.720 10.09 1.517 4.065 10.23 1.660 4.620 10.69 1.884 4.760 10.81 1.943 4.850 10.90 1.976 5.330 11.54 2.17 Pkal = 4.14 Pka2 = 9.99 -4 -3 5.00 x 10 moles B.A. and 9.40 x 10 moles KNO^. Total initial volume, 9 8 . 7 ml. Equal volumes of dioxane and 0.2007 N NaOH. 35°C. 131 Table 93. Titration of 2-(aminomethyl) benzoic acid and cobalt at ionic strength = 0. 1 with CH = 0.60 x 10“3 .

M l . base pH pHCorr. n 2.287 6.12 0.00 6.21 2.400 7.46 0.12 4.88 2.483 7.91 0.37 4.45 = 4.31 X 2.582 8.20 0.65 4.18 2.680 8.42 0.97 3.98 (log k..k_)/2=3.96 X c. 2.770 8.60 1.11 3.82 2.880 8.74 1.43 3.71 = 3.62 d 2.960 8.93 1.575 3.54 3.210 9.25 2.02 3.29

In the total initial volume of 98.7 ml., A = C>.00, C = 4.79 x 10~3, CM = 0.60 x 1 0 % and enough KN0 was present to make the ionic strength = 0 .10. Equal volumes of dioxane and 0.2007 N NaOH were added. 50 volumei °/o dioxane . 35°C.

Table 94. Titration of 2-(aminomethyl) benzoic acid and cobalt at ionic strength = 0.1 with C_, = 1.20 x 10“3. M

Ml. base pH ^Corr. n

2.505 6.66 0.00 5.64 2.605 7.52 0.115 4.80 2.730 7.84 0.325 4.50 Cn = 4.31 X 2.816 8.02 0.44 4.34 2.920 8.14 0.61 4.24 (log k k )/2=4.07 X d 3.065 8.29 0.84 4.12 3.210 8.43 1.08 4.02 C9 = 3.94 C. 3.380 8 .5 0 1.35 3.99 3.670 8.72 1.83 3.85

In the total initial volume of 98.7 ml., A = C'.00, CR = 5.14 x 10-3, CM = 1.20 x 10 and enough KN0 was present to make the ionic ✓ strength = 0 .10. Equal volumes of dioxane and. 0.2007 N NaOli were added.

50 volume °/o dioxane. 35°0. 132 Table 95. Titration of 2-(aminomethyl) benzoic acid and nickel at ionic strength = 0 .1 with = 0.5 4 7x 10“^.

lul. base pH pR * Corr. n

2.243 5.84 0 .0 8 6.51 2.340 6.90 0.135 5.44 II 2.455 7.48 0.50 4.89 0 4.89 2.540 7.85 0.79 4.44 M 2.650 8.19 1.14 4 .2 2 (log klk2 2.768 8.51 1.45 3.93 2.853 8.76 1.63 3.70 3.85 °2 = 2.980 9.0 2 1.81 3.47 3.060 9 .2 0 1.81 3.32

In the total initial volume of 98.7 ml., A - 0.00, C 4.70 x 10~3, xi C,, = O .547 x 10 J , and enough KiiO^ was present to Eijake the ionic strength = 0.10. Equal volumes of dioxane and 0.2007 N NaOH were added. 50 volume yj dioxane. 35°C. Table 96, Titration of 2 -(aminomethyl) benzoic acid ana nickel

at ionic £strength = 0 .1 with 094 x i o -^t .. . = 3"

LI1 . base pR ^Corr. n

2.167 5.05 0.00 7.30 2.340 5.50 0.0 0 6.83 2.500 6 .64 0 .10 5 .68 4.95 C1 = 2.605 7.09 0.27 5.25 2.700 7.35 0.45 5.01 (log k k )/2=4.45 1

In the total initial volume of 9s. 7 ml., A = 0.00, = 5.01 x 10-3, - 1.094 x 10 and enough KHO^ was present to m.lce the ionic strength = 0.10. Equal volumes of diox. no and 0.2007 N NaOH were added. 50 volume yo dioxane. 35°C. 133 Table 97. Titration of 2-(aminomethyl) benaoic acid, and copper at ionic strength = 0.1 with = 0.70 x 10-3.

HI. base pR P^Corr. n 1.040 3.98 0.13 8.71 1.525 4.30 0.12 8.24 1.900 4.58 0.17 7.86 C1JL : 2.110 4.77 0.20 7.64 2.310 5.02 0.27 7.35 (lo,(log ^ 2 )72=6 .29 2.500 5.30 0.44 7.06 2.620 5.58 0.525 6.77 cpd = 2.740 5.83 0.80 6.54 2.840 6.14 1.06 6.24 2.960 6.5O 1.35 . 5.90 3.080 7.12 1.69 5.30 3.200 8.08 1.95 4.37 3.300 8.80 1.98 3.68 the total initial volume of 98.7 ml., A = 0.00, C_ = 5 A —= n0.70 VO X -v 10-'5,1 C\ ^ and anonenough 'rPi KN0_ lOlTH was TJQ onr TniQciorTt* esent to +rtmake w iV othe i nriT n M 3 strength = 0.10. Equal volumes of dioxane and 0.2007 N NaOH were added. 50 volume % dioxane. 35°C. Table 98. Titration of 2-(aminomethyl) benzoic acid and cop-per ------at ionic strength =0.1 with Cjj = 1 .4 0 x 10

Ml. base pR pHCorr. n 1.000 3.94 0.00 8.79 1.500 4.25 0.01 8.32 1.900 4.54 0.15 7.94 C = 7.07 2.000 4.64 0.16 7.81 2.115 4.73 0.19 7.70 (log k.k_)/2=6. 2.253 4.86 0.24 7.56 1 2 2.397 5.00 0.32 7.41 C = 5.86 2.542 5.18 0.38 7.22 ^ 2.720 5.41 0.54 7.00 2.820 5.54 0.64 6.88 2.963 5.74 0.81 6.70 3.100 5.94 0.97 6.52 3.240 6.19 1.21 6.30 3.340 6.38 1.30 b.14 3.440 6.60 1.44 5.95 3.353 6.84 1.59 5.74 3.660 7.20 1.74 5.41 3.790 8.21 1.92 4.46 3.880 8.82 1.98 3.88 Table 98 Continued.

In the total initial volume of 98.7 ml., A = 0.00, C_ = 5.00 x 10 , -3 CM = 1 .4 0 x 10 , and enough KNO^ was present to make the ionic strength = 0.10. Equal volumes of dioxane and 0.2007 N NaOH were added. 50 volume fo dioxane. 35°C. 135 Table 99. Titration of 2-(aminomethyl) benzoic acid and zinc at ionic strength =0.1 with = 0.57 x 10-3.

Ml. base pR ^Corr. n

2.000 4.80 0.00 7.59 2.300 5.39 0.00 6.93 2.400 5.95 0.00 6.34 Cn = 5.52 1 2.500 6.55 0.04 5.76 2.610 6.82 0.46 5.51 (log kLk )/2= 2.720 6.95 0.87 5.40 2.820 7.12 1.17 5.25 C„ = 5.12

In the total initial volume of 98.7 ml., A = 0 .00, C = 5.06 x 10"5 CM = 0.57 x 1 0 % and enough KNO^ was present to make the ionic strength = 0 .10. Equal volumes of dioxane and 0.2007 N NaOH were added. 50 volume $ dioxane . 35°C.

Table 100. Titration of 2-(aminomethyl) benzoic acid andzinc at ionic ;strength =0.1 with 0^=1,,14 x 10-3.

Ml. base pH pR ^ Corr. n 2.505 6.41 0.01 5.90 2.545 6.54 0.07 5.77 2.615 6.63 0.21 5.70 = 5.61 2.712 6.72 0.39 5.63 2.810 6.75 0.555 5.61 (log Idk )/2=! X & 2.915 6.83 0.755 5.56 3.020 6.89 0.92 5.52 C„ = 5.38 c. 3.125 6.95 1.12 5.48 3.265 7.04 1.38 5-43 3.435 7.24 1.64 5.27 3.645 8.31 1.99 4.27 In the total initial volume of 98.7 ml., A = 0.00, = 5.09 x 10-^, C —3 M = 1.14 x 10 , and enough KI'IO^ was present to make the ionic strength = 0.10. Equal volumes of dioxane and 0.2007 N HaQH were added. 50 volume i» dioxane. 35°0. 136 Table 101. Titration of 2-(aminomethyl) benzoic acid and cadmium at ionic strength = 0.1 with .525 x 10-3. CM = °'

Ml. base pR P^Corr. n 2.300 5.24 0.00 7.09 2.460 6.20 0.00 6.10 2.560 7.51 0.22 4.81 Cn = 4.32 X 2.660 7.99 0.48 4.34 2.760 8.32 0.805 4.03 (log k n k )/2=3.75 X d 2.860 8.64 0.97 3.73 3.065 8.89 1.50 3.52 0 o = 3.49 d 3.242 9.14 1.87 3.32

In the total initial volume of 98.7 ml., A = 0,.00, C = 5.11 X 10~3 , CM = 0.525 x 10~3 , and enough KW0_ was present to make the ionic strength = 0,.10. Equal volumes of dioxane and 0.2007 i'l NaOH were added. 50 volume P dioxane . 35°C.

Table 102. Titration of 2-(aminomethyl) benzoic acid and cadmium at ionic strength = 0.1 with = 1.,05 x 10“3.

Ml. base pR ^Corr. n

2.255 5.20 0.01 7.15 2.380 5.75 0.00 6.56 2.480 7.05 0.06 5.17 C. = 4.36 X 2.580 7.63 0.24 4.72 2.640 7.84 0.3b 4.51 (log k k )/2=4.02 1 d 2.750 8.04 0.545 4.34 2.845 8.19 0.705 4.21 c_ = 3.61 d 2.935 8.32 0.835 4.09 3.070 8.49 1.08 3.96 3.200 8.65 1.29 3.83 3.340 8.82 1.51 3.70 3.545 9.05 1.82 3.53

In the total initial volume of 98.7 ml., a = 0,.00, CR = 4.99 x 10"3 , -3n. = 1.0 5 x 10 , and enough KNO^ was present to make the ionic strength = 0.10. Equal volumes of dioxane and 0.2007 N NaOE were added. 50 volume °/o dioxane. 35°C. 137 Table 103. Titration of salicylic acid in 50 volume fo dioxane

HI. base ^Corr. a

0.000 2.30 0.000 0.510 2.39 0.204 1.005 2.53 0.404 1.490 2.69 0.597 2.000 2.91 0.802 2.323 3.14 0.931 2.435 3.20 0.976 2.560 3.31 1.013 2.980 3.60 1.097 3.500 3.89 1.203 3.990 4.08 1.302 4.500 4.27 1.405 4.990 4.45 1.503 5.500 4.60 1.606 6.000 4.80 1.707 6.500 5.06 1.808 7.000 5.47 1.909 7.190 5.69 1.946 7.320 6.09 1.974 7.370 6.59 1.984 7.433 7.90 1.996 7.510 10.19 2.013

5.00 x 10-4 moles HNO and 9.92 x 10 4 moles of salicylic acid. Total initial volume, 98.7 ml. Equal volumes of dioxane and 0.2001 N NaOH added. 35°C. pH

2 -

0.0 0 .5 0 1.0 1.5 2.0 a

FIGURE 29. p H -a CURVE FOR SALICYLIC ACID FROM TABLE 103 •138 139 Table 104. Titration of salicylic acid and cobalt

HI. base pR pHCorr. n

2.500 3.18 0.15 3.31 2.900 3.47 0.17 3.03 3.300 3.69 0.33 2.87 = 2.63 C1X : 3.600 3.85 0.35 2.74 4.000 4.00 0.54 2.64 (log(lo. k ^ ) / 2=2.34 4.400 4.17 0.58 2.53 4.800 4.29 0.84 2.47 = 2.23 C?2 : 5.200 4.45 0.75 2.38 5.620 4.59 0.915 2.34 6.020 4.70 1.57 2.34 6.400 4.95 1.58 2.23 6.800 5.19 1.36 2.21

In the total initial volume of 98.7 ml., A = 5.06 x 10~3, 3r = 9.99 x _3 10‘3 , CM = 1 .20 x 10 . Equal volumes of dioxane and 0.2( 31 N NaOH were added. 50 volume 7° dioxane. 35°C.

Table ,105. Titration of salicylic acid and cadmium

M l . base '“t o m n pR

2.000 2.79 0.435 3 .6 8 2.500 3.06 0.49 3.42 2.900 3.30 0.635 3.21 °1X : 3.300 3.56 0.78 2.98 3.705 3.77 0.59 2.80 (lo* 2= 2 .16 4.100 3.94 1.10 2.69 4.500 1.32 4.09 2.59 C? : 4.900 4.22 1.56 2.52 5.300 4.37 1.625 2.44 5.700 4.50 2.02 2.40 6.100 4.67 1.99 2.33 6.500 4.87 1.91 2.27

In the total initial volume of 98.7 ml., A = 5.06 x 10-5, CR = 10.38 x 1 0 1 0 1 — —! -3 11 g 1 .05 x 10 . Equal volumes of‘ dioxane and 0.2( were added. 50 volume cJo dioxane. 35°C. 140 Table 106. Titration of salicylic acid and nickel

HI. base pR ^Corr. n

2.390 3.10 0.155 3.37 2.690 3.31 0.19 3.18 2.980 3.49 0.275 3.02 = 2.72 3.280 3.66 0.37 2.88 3.700 3.86 0.49 2.72 (log k1k2 )/2=2.52 3.995 3.97 0.66 2.65 4.385 4.10- 0.90 2.57 C2 = 2.27 4.700 4.24 0.76 2.48 5.000 4.31 1.14 2.45 5.400 4.45 1.315 2.39 5.800 4.59 1.39 2.33 6.210 4.77 1.44 2.28 6.500 4.89 1.74 2.26 6.780 5.07 1.59 2.22

In the total initial volume of 98.7 ml., A = 5.06 x 10-^, C„ = 10.32 x -3 -3 10 , C,r = 1.094 x 10 • Equal volumes of dioxane and 0.2001 N NaOH 0 were added. 50 volume ft dioxane. 35 C.

Table 107. Titration of salicylic acid and copper

Ml. base pR ■^Corr. n 1.520 2.66 0.06 3.80 1.990 2.85 0.06 3.63 2.400 3.02 0.31 3.48 C1 = 3.23 2.700 3.18 0.425 3.33 2.990 3.31 0.53 3.17 (log k_kJ/2=2.84 3.300 3.50 0.73 3.05 3.700 3.72 0.88 2.88 C2 ( = 2.62 4.100 3.88 1.11 2.77 4.510 4.04 1.33 2.67 4.900 4.17 1.585 2.61 5.300 4.29 1.93 2.56 5.700 4.44 2.25 2.51 6.100 4.58 2.57 2.48 6.500 4.74 3.10 2.47

the total initial volume of 98.7 ml., A = 5.06 x 10" C = 10.02 x -3 -3 10 , Cjj = 1.40 x 10 . Equal volumes of dioxane and 0.2001 N NaOH were added. 50 volume dioxane. 35°C. 141 Table 108. Titration of salicylic acid and zinc

Ml. base pR ^Corr. n

2.000 2.83 0.25 3.64 2.504 3.12 0.305 3.36 2.890 3.39 0.335 3.12 C1 i = 2.83 3.300 3.63 0.41 2.91 3.700 3.83 0.61 2.76 (log k1k 2)/2=2.55 4.100 3.99 0.78 2.64 4.500 4.12 1.06 2.57 C2 ' = 2.35 4.900 4.27 1.11 2.48 5.300 4.41 1.23 2.41 5.700 4.54 1.56 2.37 6.100 4.70 1.61 2.31 6.500 4.89 1.70 2.26 6.900 5.14 1.84 2.22 7.300 5.61 1.57 2.16

the total initial volume of 98.7 ml., A. = 5.06 x 10'-5 CR = 10.30 x 10 C - 1 .14 x 10 . Equal volumes of dioxane and < » °l-i “ 1 ■e added. 50 volume P dioxane. 35°C. 1 4 2 Table 109. Titration, of O-(carboxymethoxy) benzoic acid in

50 volume c/q dioxane

Ml. base pH., a r Corr. 0.000 2.30 0.000 0.980 2.53 0.393 2.000 2.87 0.801 2.300 3.05 0.921 2.400 3.11 0.961 2.500 3.19 1.002 2.610 3.28 ’ 1.041 2.995 3.55 1.196 3.395 3.79 1.352 3.800 4.07 1.511 3.895 4.15 1.549 4.005 4.19 1.591 4.400 : 4.48 1.746 4.800 5.03 1.904 5.000 5.57 1.981 5.160 5.96 2.044 5.260 6.15 2.083 5.500 6.45 2.178 6.000 6.87 2.372 6.400 7.10 2.530 6.500 7.18 2.569 6.610 7.26 2.613 7.025 7.60 2.775 7.400 8.16 2.92 7.500 8.49 2.96 7.562 9.08 2.986 7.600 9.84 3.000 7.625 10,40 3.007 7.740 11.19 3.04 pkal = 4,05 pka2 = 5.10 x 10 \ 10les of B.A. and 5.00 x 10 ^moles HNO . Total initial volume, 98.7 ml. Equal volumes of dioxane and 0.2001 N NaOH added. 35°C. 12

0.0 0.4 0.8 1.2 1.6 2.0 2.4 2.8 a

FIGURE 30. p H -a CURVE FOR 0~ (CARBOXYMETHOXY)-BENZOIC ACID FROM TABLE 109 Table 110. Titration of o-(carboxymethoxy)-benzoic acid and cobalt with C = 0.60 x 10“3 M

Ml. base pR ^Corr. n

2.700 3.26 0.21 6.95 3.000 3.46 0.27 6.60 3.300 3.65 0.36 6.28 log k = 5.97 3.600 3.82 0.48 6.00 3.900 3.98 0.63 5.76 4.200 4.17 0.67 5.48 4.500 4.37 0.82 5.22 4.800 4.62 0.88 4.92 5.000 4.86 0.96 4.64 5.200 5.24 1.00 4.26 5.400 5.79 1.13 3.69 5.605 6.24 1.075 3.31

In the total initial volume of 98.7 ml. , A = 5.06 x 10-3, Cg=5.07 x icT 3 , CH - 0>.c0 x 10 . Equal volumes of dioxane and 0.2001 N NaOH were added. 50 volume i° dioxane. 35°C •

Table 111. Titration of O-(carboxymethoxy)-benzoic acid and cobalt with C„ = i.; 20 x 10-3. M

Ml, base pR ^Corr. n

2.400 3.09 0.05 7.29 2.700 3.27 0.05 6.95 3.000 3.45 0.18 6.64 log k = 5.56 3.300 3.61 0.27 6.37 3.600 3.79 0.52 6.07 3.900 3.96 0.38 5.81 4.210 4.10 0.505 5.62 4.500 4.29 0.545 5.37 4.800 4.48 0.705 5.14 5.100 4.77 0.82 4.80 5.400 5.26 0.94 4.29 5.600 5.84 1.02 3.72 -3 In the total initial volume of 98.7 ml., A = 5.06 x 10 , Cu = 4.90 -3 -3 10 , C. = 1.20 x 10 . Equal volumes of dioxane and 0.2001 N NaOH , o were added. 50 volume L/o dioxane. 35 C, Table 112. Titration of o-(carboxymethoxy)-benzoic acid and nickel with = 0.547 x 10-3.

Ml. base pR ^Corr. n

2.000 2.85 0.15 7.72 2.400 3.06 0.19 7.33 2.690 3.24 0.27 6.99 3.000 3.45 0.31 6.61 log k = 6.03 3.320 3.65 0.41 6.27 3.590 3.80 0.51 6.03 3.900 3.99 0.59 5.74 4.200 4.17 0.71 5.48 4.500 4.37 0.86 5.22 4.800 4.62 0.96 4.91 5.100 5.07 0.985 4.41 5.300 5-56 1.05 3-90 5.500 6.07 1.12 3.42 -3 the total initial volume of 98.7 ml., A = 5.06 x 10 , C = 5.1C 10 ^ = 0.547 xlO5. Equal volumes of dioxane and 0.2001 N NaOH were added. 50 volume jo dioxane. 35°C. Table 113. Titration of o-(carbox.ymethoxy)-benzoic acid and nickel with C_. = 1.094 x 10”^. M

Ml. base pH„ — pH r Corr. n r

2.000 2.85 0.08 7.74 2.400 3.07 0.085 7.32 2.700 3.26 0.125 6.97 log k = 5.68 3.000 3.44 0.185 6.65 3.300 3.62 0.30 6.34 3.600 3.79 0.325 6.06 3.900 3.96 0.40 5.81 4.200 4.10 0.535 5.62 4.500 4.29 0.645 5.36 4.800 4.50 0.73 5.10 5.100 4.81 0.84 4.75 5.400 5.40 0.94 4.13

In the total initial volume of 98.7 ml., A = 5.06 x lO-"5, C„ = 4.95 x -3 -3 10 , Cj^ = 1.094 x 10 . Equal volumes of dioxane and 0.2001 N iiaOH were added. 50 volume fo dioxane. 35°C. Table 114. Titration of o-(carboxyraethoxy)-benzoic acid and copper with = 0.70 x 10“3 .

Ml. base pR ^Corr. n

1.995 2.77 0.355 7.91 2.390 2.91 0.525 7.65 2.700 3.07 0.65 7.36 3.000 3.20 0.785 7.12 3.300 3.38 1.05 6.81 3.600 3.57 1.01 6.47 3.900 3.76 1.11 6.16 4.200 3.97 1.16 5.83 4.500 4.18 1.28 5.53 4.800 4.47 1.175 5.14 5.110 4.87 1.20 4.67 _3 In the total initial volume of 98.7 ml., A = 5.06 x 10 , CL = 4.94 -3 -3 K 10 , C = 0.70 x 10 . Equal volumes of dioxane and 0.2001 N NaOH were added. 50 volume dioxane. 35°C. Table 115. Titration of o-(carboxymethoxy)-benzoic acid and " ------copper with = 1.40 x 10

Ml. base pR ^Corr. n 1.000 2.48 0.07 8.45 1.495 2.59 0.09 8.25 2.000 2.75 0.22 7.95 log k = 7.34 2.400 2.87 0.33 7.73 2.800 3.02 0.445 7.47 3.205 3.19 0.58 7.19 3.500 3.29 0.665 7.00 3.805 3.45 0.80 6.73 4.100 3.59 0.905 6.5 0 4.400 3.78 0.97 6.18 4.700 3.99 1.02 5.87 5.000 4.24 1.07 5.52 5.300 4.57 1.07 5.10 5.600 5.20 1.08 4.40 5.800 5.90 1.15 3.71

In the total initial volume of 98.7 ml., A = 5.06 x 10 C = 4.98 -3 -3 10 , CTi, = 1.40 x 10 . Equal volumes of dioxane and 0.2001 N iteOH i’l were added. 50 volume dioxane. 35 C. 147 Table 116. Titration of o-(carboxymethoxy)-benzoic acid and zinc with CH = 0.57 x 10 .

Ml. base pH pR Corr. n 1.500 2.65 0.04 8.11 2.000 2.85 0.145 7.73 2.400 3.05 0.22 7.36 2.700 3.20 0.41 7.10 3.000 3.37 0.54 6.78 3.300 3.51 0.80 6.55 3.600 3.68 0.92 6.26 3.920 3.87 1.10 5.96 4.200 4.03 1.22 5.72 4.500 4.25 1.30 5.41 4.800 4.49 1.36 5.11 5.100 5.00 1.18 4.50 5.300 5.59 1.15 3.89 In the total initial volume of 98.7 ml., A = 5.06 x 10 , C = 5.00 x -3 -3 10 , = 0.57 x 10 . Equal volumes of dioxane and 0.2001 N NaOH were added. 50 volume “/o dioxane. 35°C.

Table 117. Titration of o-(carboxymethoxy)-benzoic acid and zinc with C„. = 1.14 x 10“ . M

Ml. base pH Corr. n pH 1.500 2.65 0.01 8.11 1.995 2.80 0.135 7.83 2.395 2.99 0.20 7.47 log k = 6.63 2.790 3.19 0.29 7.10 3.190 3.37 0.40 6.79 3.595 3.56 0.59 6.47 4.000 3.75 0.77 6.17 4.400 3.97 0.885 5.84 4.800 4.25 0.98 5.45 5.200 4.65 1.00 4.94 5.400- 4.97 1.11 4.58 5.515 5.23 1.025 4.31 5.600 5.57 1.04 3.96 5.770 5.87 1.16 3.69 5.800 o.08 1.11 3.48 6.000 6.39 1.17 3.22 In the total initial volume oi 98.7 ml. , A = 5.06 x 10“3 , C„ = 5.10 II -3 —■=5 .14 x 10 . Equal volumes of dioxane and 0.2001 N NaOH were added. 50 volume dioxane. 35°C • Table 118. Titration of o-(carboxymethoxy)-benzoic acid and cadmium with = 0.525 x 10 .

Ml. base pR ^Corr. n

2.000 2.81 0.34 7.83 2.400 3.02 0.36 7.43 2.705 3.23 0.36 7.04 log k = 6.38 3.000 3.43 0.445 6.68 3.300 3.64 0.51 6.31 3.600 3.84 0.55 5.98 3.900 4.03 0.62 5.70 4.200 4.20 0.745 5.46 4.500 4.46 0.79 5.12 4.800 4.78 0.88 4.74 5.000 5.08 0.965 4.41 5.200 5.61 1.05 3.88 In the total initial volume of 98.7 ml., A = 5.06 x 10 C = 4.88 x _ r r _ -z R 10 , Cjtj = 0.525 x 10 . Equal volumes of dioxane and 0.2001 IT NaOH were added. 50 volume ft dioxane. 35°C.

Table 119. Titration of o-(carboxvmethox.y)-benzoic acid and cadmium with = 1205 x 10-3.

Ml. base pH_ — pR * Corr. n *

2.000 2.85 0.08 7.73 2.400 3.05 0.12 7.36 2.700 3.24 0.17 7.00 log k = 5.17 3.000 3.45 0.19 6.63 3.310 3.64 0.255 6.30 3.600 3.80 0.32 6.04 3.900 3.99 0.35 5.75 4.200 4.17 0.415 5.49 4.600 4.44 0.51 5.14 4.900 4.70 0.605 4.84 5.200 5.09 0.74 4.42 5.400 5.49 0.855 4.02

In the total initial volume of 98.7 ml., A = 5.06 x 10 , CL, = 5.00 x -3 -3 10 , = 1.05 x 10 . Equal volumes of dioxane and 0.2001 N NaOH were added. 50 volume dioxane. 35°C. 149 Table 120. Titration of N-(carboxymethyl) anthranilic acid

in 50 volume ? ° dioxane.

Ml. base pH * Corr. a 0.000 2.30 0.000 0.980 2.50 0.390 2.020 2.98 0.810 2.270 3.29 0.910 2.416 3.65 0.970 2.565 4.11 1.028 2.970 4.79 1.190 3.290 5.08 1.318 3.595 5.29 1.440 3.795 5.43 1.519 3.990 5.55 1.597 4.400 5.77 1.761 4.800 6.06 1.920 5.20 6.30 2.080 5.617 6.59 2.25 6.005 6.85 2.402 6.200 6.97 2.48 6.300 7.01 2.52 6.500 7.12 2.60 6.900 7.43 2.76 7.200 7.76 2.88 7.425 8.19 2.97 7.460 8.32 2.987 7.520 8.77 3.005 7.580 10.11 3.03 7.900 11.55 3.16 C1 = 5.40 C2 = 7.00 Convergence correction is 0.04.

pkal = 5,44 pka2 = Table 120 Continued. -4 -4 5.00 x 10 moles HNO^ and 5.00 x 10 moles A .A. Total initial volume, 98.7 ml. Equal volumes of dioxane and 0.2001 N NaOH added. 35°C. ______I------L_ ------1------1______l______I______I______I__ 0 0.4 0.8 1.2 1.6 2.0 2.4 2.8 3.2 a

FIGURE I. pH -a CURVE FOR N - (CARBOXY METHYL) - ANTHR AN 1LIC ACID FROM M TABLE 120. h 152 Table 121. Titration of N-(carboxymethyl)-anthranilic acid and cobalt with C., = 0.60 x 10-5.

Ml. base pHn pR Corr. n

1.995 2.97 0.07 8.78 2.595 3.54 0.04 7.64 2.590 3.99 0.11 6.76 C = 5.68 2.300 4.29 0.28 6.19 3.000 4.50 0.44 5.79 (log k k )/2=4.48 3.200 4.68 0.62 5.47 1 d 3.405 4.86 0.74 5.15 C = 3.10 3.600 4.99 0.86 4.93 ^ 3.900 5.20 1.01 4.59 4.200 5.41 1.03 4.27 4.600 5.67 1.15 3.91 5.000 5.90 1.30 3.65 5.400 6.24 1.41 3.28 5.800 6.54 1.55 3.03 6.200 6.83 1.73 2.84 -5 In the total initial volume of 93.7 ml.. A = 5.06 x 10 . C„, = 0.60 x -3 10 3 , C = 4.95 x 10 . Equal volumes of dioxane and 0.2001 N NaOH were added. 50 volume fa dioxane., 35°C. Table :122. Titration of N-(carboxymethyl)-anthranilic acid and cobalt with C = 1.20 x 10-3. ri.

Ml. base pH_ ~ oR -1 Corr. n 2.000 3.00 0.01 8.70 2.300 3.36 0.00 7.98 2.490 3.74 0.03 7.23 Cn = 5.64 .L 2.700 4.06 0.12 6.61 2.895 4.27 0.22 6.22 (log k.k_)/2=4.28 J.

Kl. base pHCorr. —n rpR

2.000 2.98 0.04 8.75 2.400 3.49 0.08 7.74 2.590 3.74 0.25 7.26 C, = 6.70 2.800 4.01 0.48 6.73 3.000 4.22 0.74 6.34 (log k Llc2)/2=5.: 3.200 4.49 0.955 5.84 3.405 4.77 0.96 5.32 C 0 = 4.05 11 3.610 4.95 1.04 5.00 3.900 5.17 1.135 4.63 4.200 5.37 1.25 4.33 4.600 5.58 1.54 4.04 5.000 5.87 1.81 3.68

In the total initial volume of 98.7 ml., A = 5.06 x 10 C = 5.01 x 10'5 , CM = 0 .547 x 10 . Equal volumes of dioxane and 0.2001 N NaOH were added. 50 volume j'o dioxane. 35°C. Table 124. Titration of N-(carboxymethyl)-anthranilic acid and nickel with = 1.094 x 10~3.

Ml. base — pR P^Corr. n r

2.000 2.97 0.00 8.72 2.400 3.39 0.08 7.93 2.600 3.62 0.17 7.49 C, = 6.83 X 2.900 3.88 0.38 7.00 3.200 4.09 0.71 6.62 (log lmk )/2=5.. X u 3.510 4.35 0.81 6.13 3.800 4.64 0.955 5.60 C 0 = 4.10 c. 4.120 4.90 1.085 5.14 4.400 5.13 1.18 4.76 4.700 5.31 1.28 4.49 5.000 5.49 1.39 4.24 5.400 5.70 1.625 3.98 5.800 6.00 2.04 3.69 In the total initial volume of 98.7 ml., A = 5*06 x 10 , Ck = 5.11 x -3 -3 10 , = 1.094 x 10 . Equal volumes of dioxane and 0.2001 N NaOH were added. 50 volume 'f t dioxane. 35°C. 154 Table 125. Titration of i'f-(carboxymethyl)-anthranilic acid and copper with = 0.70 x 10“3.

Ml. base pR ^Corr. n

0.000 2.28 0.13 10.16 0.520 2.35 0.36 10.04 1.000 2.45 0.63 9.85 1.505 2.56 0.59 9.64 log ^ = 9.78 2.000 2.70 0.745 9.38 2.295 2.83 0.78 9.12 2.590 2.97 0.80 8.85 2.900 3.25 1.11 8.51 (log k k )/2=6.06 3.095 3.61 0.99 7.59 Calc. 3.290 4.20 1.05 6.43 3.495 4.67 1.03 5.54 3.710 4.94 1.05 5.06 3.905 5.15. 1.00 4.70 log k„ = 2.74 cL 4.200 5.37 1.04 4.35 4.500 5.59 1.10 4.04 4.800 5.81 1.16 3.76 5.100 6.08 1.14 3.45 5.400 6.30 1.19 3.24 5.800 6.62 1.28 2.98 6.200 6.93 1.34 2.78 6.600 7.24 1.715 2.68

In the total initial volume of 98.7 ml., A = 5.06 x 10 , CM = 0.70 x -3 -3 10 , = 4.80 x 10 . Equal volumes of dioxane and 0.2001 N NaOH were added. 50 volume 'i<> dioxane. 35 C. 2.0

0.8

0 .4

00 2.0 3 .0 4 . 0 5 .0 6.0 7 .0 8.0 9 . 0 10.0 11.0 PR

FIGURE 32. pR-n CURVE FOR N - (CARBOXYMETHYL)-ANTHRANILIC ACID AND COPPER FROM TABLE 1 2 5 156 Table 126. Titration of If-(carboxymethyl)-anthranilic acid and copper with C = 1.40 x 10-3.

Ml. base pR ^Corr. n

1.200 2.47 0.30 9.79 1.600 2.55 0.38 9.64 1.995 2.63 0.50 9.50 log = 9.50 2.400 2.73 . 0.62 9.32 2.800 2.85 0.75 9.11 3.200 3.04 0.85 8.75 3.590 3.35 0.95 8.15 3.990 4.39 1.00 6.11 Calc. 4.200 4.79 0.99 5.36 . 2.77 4.400 4.98 1.00 5-05 ' 4.610 5.27 0.99 4.54 5.000 5.57 1.00 4.10 5.400 5.89 1.00 3.69 5.800 6.20 1.13 3.39 6.200 6.57 1.12 3.06 6.600 6.87 1.27 2.88 7.000 7.21 1.495 2.77 7.400 7.73 1.94 2.74 -3 the total initial volume A = 5.06 x 10" of 98.7 ml., M 10~3 , C R = 5.14 x lO-3. Equal volumes of dioxane and 0.2001 N NaOH were added. 50 volume yo dioxane. 35 C. 157 Table 127. Titration of IT-(carboxymethyl)-anthranilie acid and zinc with C,T = 0.57 x 10-3. M

I'll • base pR ^Corr. n 2.000 3.00 0.00 8.71 2.400 3.55 0.06 7.62 2.600 4.03 0.09 6.68 C. = 5.54 1 2.790 4.34 0.24 6.08 3.000 4.56 0.425 5.68 3.290 4.80 0.635 5.24 3.600 5.07 0.715 4.78 (log k k )/2=4.: 3.907 5.49 0.81 4.46 x * Calc 4.235 5.49 0.82 4.13 4.500 5.68 0.86 3.87 4.810 5.87 0.98 3.64 c9 = 2.71 d 5.100 6.09 0.99 3.40 5.400 6.30 1.19 3.33 5.800 6.60 1.06 2.94 6.200 6.87 1.34 2.77 In the total initial volume of 98.7 ml., A = 5.06 x 10~3 , C„ = 5.00 x 7 10 , C = 0.57 x 10 . Equal volumes of dioxane and 0.2001 N NaOH were added. 50 volume 'yo dioxane. 35°C.

Table !128. Titration of N-(carboxymethyl)-anthranilic acid and zinc with CT. = 1.14 x 10-3. M

M l . base - pR *HCorr. n 1

1.995 2.99 0.02 8.71 2.400 3.50 0.03 7.70 2.590 3.89 0.12 6.93 Cn = 5.63 2.900 4.28 0.22 6.19 3.200 4.49 0.43 5.81 3.500 4.69 0.58 5.45 3.800 4.88 0.73 5.13 4.100 5.08 0.825 4.80 (log k k )=4.20 4.400 5.27 0.92 4.50 1 ^ Calc. 4.700 5.49 0.93 4.17 5.000 5.67 1.00 3.93 5.300 5.89 1.03 3.66 5.700 6.19 1.14 3.35 6.000 6.44 1.13 3.12 CQ = 2.77 d . 6.400 6.71 1.375 2.93 6.800 7.03 1.52 2,76 7.200 7.37 1.715 2.69 Table 128 Continued. -3 In the total initial volume of 93.7 ml., A = 5.06 x 10 , = 5.24 10 3, = 1.14 x 10~3. Equal volumes of dioxane and 0.2001 N NaOH were added. 50 volume °/> dioxane. 35 C. 2 .0 h

0.8

0.4

3.0 3.5 4.0 5.5 6.0 6.5 705.0 754.5 PR

FIGURE 33. n-pR CURVE FOR N - (CARBOXYMETHYL)-ANTHRANILIC ACID AND ZINC FROM K TABLE 128 ^ 160 Table 129. Titration of M-(carboxymetliyl)-anthranilic acid and cadmium with C = 0.525 x 10“3.

Ml. base pR ^Corr. n

2.000 2.97 0.06 8.77 2.395 3.43 0.06 7.76 2.600 3.97 0.14 6.80 0 1 = 5.25 2.795 4.35 0.24 6.06 3.000 4.59 0.425 5.62 3.200 4.79 0.53 5.26 3.520 5.05 0.635 4.81 1 2 ' 3.910 5.29 0.82 4.43 Calc. 4.300 5.53 0.95 4.03 4.700 5.79 1.06 3.74 5.100 6.08 1.12 3.41 5.500 6.37 1.46 3.46 C2 = 2.73 5.900 6.67 1.30 2 .90 6.320 6.94 1.46 2.75 6.700 7.19 2.20 2.68 In the total initial volume of 98.7 ml., A = 5.06 x 10 , C = 5.00 x K -3 -3 10 , C = 0.525 x 10 . Equal volumes of dioxane and 0.2001 N NaOH were added. 50 volume % dioxane. 35°C.

Table 130. Titration of N-(carboxvmethvl)-anthranilic acid and cadmium with = 1.05 x 10“3.

Ml. base pR ■^Corr. n 2.000 2.99 0.02 8.73 2.395 3.47 0.04 7.78 2.600 3.90 0.09 6.93 0 ± = 4.98 2.900 4.39 0.20 5.99 3.200 4.67 0.33 5.48 3.500 4.90 0.47 5.08 3.810 5.10 0.59 4.75 4.100 5.28 0.68 4.47 4.400 5.47 0.75 4.19 Calc. 4.730 5.68 0.78 3.91 5.020 5.87 0.86 3.68 5.600 6.30 1.02 3.14 5.900 6.56 0.98 3.02 C2 = 2.66 6.200 6.77 1.11 2.89 6.600 7.09 1.16 2.72 7.000 7.45 1.51 2.65 In the total initial volume of 98.7 ml., A = 5.06 x 10''3, CR = 5.01 x 10"3 Si = x 10“3. Equal volumes of dioxane and 0.2001 N NaOH were added. 50 volume fo dioxane. 35°C. 161 Table 131. Titration of anthranilic acid diacetic acid in

50 volume % dioxane.

Ml. base ^Corr a

0.000 2.30 0.000 1.000 2.51 0 .4 0 1 2.000 2.96 0.801 2.5000 5.49 1.003 2.595 5.61 1.058 2.795 3.89 1.175 3.000 4.09 1.294 3.200 4.26 1.410 5.400 4.39 1.527 5.590 4.55 1.639 5.800 4.66 1.760 4.010 4.77 1.882 4.204 4.89 1.995 4.400 4.99 2.110 4.610 5.10 2.23 4.795 5.24 2.34 5.000 5.38 2.46 5.200 5.49 2.577 5.400 5.73 2.693 5.600 5.97 2.810 5.700 . 6.19 2.87 5.800 6.53 2.925 5.860 6.89 2.961 5.920 7.08 2.995 6.000 7.44 3.04 6.230 7.92 3.175 6.405 8.13 3.28 6.610 8.36 3.40 6.80 3.54 3.506 7.000 8.72 3.625 Table 131 Continued

7.200 8.97 3.74 7.400 9.29 3.86 7.510 9.59 3.92 7.570 9.95 3.96 7.640 10.47 3.995 7.685 10.70 4.02 7.745 11.06 4.06 8.020 11.67 4.22 pkal = 4 . 4 9 pka2 = 5.30 pka3 = 8,55

From C1 = 4.36 C2 = 5.43 0 ^ = 8.53

That is, a convergence correction of 0.13 was applied to and to C^, but not to C^.

5.00 x 10~\ioles 'MO''* and 3.44 x 10”^moles of k k di HAc. Total initial volume, 98.7 ml. Equal volumes of dioxane and 0.2001 N NaOH were added. 35°G. FIGURE 34. p H - a CURVE FOR ANTHRANILIC ACID DIACETIC ACID FROM TABLE Table 132. Titration of anthranilic acid diacetic acid and ?! H cobalt with CM = °*b0 •

Ml. base pR pHCorr. n

1.000 2.54 0.00 13.05 1.500 2.67 0.03 12.67 2.000 2.81 0.28 12.27 log k = 11.75 2.400 2.96 O.46 11.84 2.800 3.13 0.67 11.25 3.100 3.29 0.835 10.89 3.400 3.59 0.90 10.02 3.700 3.90 0.95 9.15 4.000 4.16 1.09 8.44 _5 In the total initial volume of 98.7 ml.. A = 5.06 x 10 , G = 4.60 imrZ 'T ^ 10 , C. = 0.60 x 10 . Jjiqual volumes of dioxane and 0.2001 K NaOH were added. 50 volume p dioxane. 35°0.

Table 133• Titration of anthranilic acid diacetic acid and cobalt with Cj. = 1.20 x 10“3.

il. base pH,, — pR Corr. n

1.000 2.49 0.06 13.20 1.490 2.610 0.12 12.85 2.000 2.74 0.22 12.48 log k = 11.91 2.400 2.84 0.34 12.20 2.710 2.90 0.44 12.04 3.000 2.98 0.555 11.81 3.300 3.07 0.665 11.57 3.595 3.16 0.775 11.32 3.895 3.29 0.87 10.95 4.200 3.49 0.96 10.38 4.500 3.82 1.00 9.44 4.800 4.09 1.03 8.70 5.100 4.30 1.05 8.16 5.400 4.51 1.03 7.64 5.700 4.67 1.06 7.28

In the total initial volume of 98.7 ml., A = 5.06 x . - t CR = 4.71 io"3, cM = 1.20 x 10-'\ iljual volumes of dioxane am 2001 N iinOH were added. 50 volume p dioxarle. 35°C. 165 Table 134. Titration of anthranilic acid diacetic acid and nickel with C„ = 0.547 x 10~3. w

Ml. base pR ^Corr. n

0.000 2.29 0.06 13.80 0.520 2.37 0.13 13.56 1.020 2.46 0 .3 0 13.31 log k = 12.95 1.490 2.55 0.435 13.05 2.000 2.69 0.65 12.65 2.500 2.87 0.81 12.13 2.800 3.02 0.8b 11.69 3.100 3.27 0.88 10.98 3.400 3.63 0.92 9.91 3.700 3.94 0.98 9.04 4.000 4.19 0.95 8.36 4.300 4.39 0.95 7.86

In the total initial volume of 95.7 nil*, A = 5.06 x 10 , C = 4.59 x -3 -3 10 , CF = 0.547 x 10 . Equal volumes of dioxane and 0.2001 N NaOH were added. 50 volume 'ft dioxane. 35°C. 'fable 135. Titrat-ion. of si.a. dl HAo and Hi with -a-n r'r'A ~ ‘iri Ml. base pR pilCorr. n

0.000 2.25 0.20 13.85 0.400 2.29 0.28 13.80 0.800 2.37 0.27 13.56 log : k = 13.01 1.200 2.43 0.335 13.39 1.590 2.50 0.42 13.19 1.990 2.57 0.51 13.00 2.400 2.66 0.61 12.74 2.800 2.76 0.72 12.46 3.200 2.89 0.815 12.09 3.600 3.09 0.87 11.51 4.000 3.39 0.98 10.63 4.400 3.85 0.99 9.32 4.820 4.19 1.02 8.40

the total initial volume of 98.7 ml., A = 5.06 x 10'"3 , C = 4.90 3 -3 -3 10 , = 1.094 x 10 . Equal volumes of dioxane and 0.2001 N NaOH were added. 50 volume f t dioxane. 35 C. 0.8

Q 6 n

0.4

0.2

0.0 8.0 9.0 10.0 11.0 12.0 13.0 14.0 pR

FIGURE 35. n-pR CURVE FOR ANTHRANILIC ACID DIACETIC ACID AND NICKEL FROM TABLE 134 Table 136. Titration of anthranilic acid diacetic acid and copper with = 0.70 x 10-3,

Ml. base pR ?HCorr. n 0.000 1.96 0.40 15.01 0.500 2.02 0.24 14.61 1.000 2.06 0.36 14.51 log k = 14.32 1.500 2.10 0.515 14.40 2.000 2.16 0.535 14.23 2.480 2.23 0.495 14.02 3.000 2.29 0.667 13.85 3.490 2.37 0.72 13.63 4.000 2.48 0.71 13.30

In the total initial volume of 98.7 ml., A = 10.12 x 10 , C = 4.68 -3 -3 10 , Cy, = 0.70 x 10 . Equal volumes of dioxane and 0.2001 N NaOH were added. 50 volume fo dioxane. 35°C.

Table 137* Titration of anthranilic acid diacetic acid and copper with = 1 .4 0 x 10“3.

Ml. base pHrt ~ pR Corr. n *

0.000 2.14 0.515 14.29 0.400 2.18 0.57 14.17 0.800 2.23 0.61 14.04 log : k = 14.32 1.180 2.28 0.64 13.94 1.595 2.35 0.66 13.69 1.985 2.40 0.705 13.56 2.400 2.49 0.74 13.30 2.810 2.59 0.785 13.01 3.200 2.71 0.79 12.65 3.600 2.87 0.855 12.19 4.000 3.09 0.907 11.72 4.400 3.42 0.84 11.57

the total initial volume of 98.7 ml., A = 5.06 x 10',-3 c 1 R ,-3 „ , _ ,„-3 10 , Cv = 1.40 x 10 . Equal volumes of dioxane and 0.2001 N NaOH were added. 50 volume i* dioxane. 35°C. 168

Table 138. Titration of anthranilic acid diacetic acid and zinc with C„T = 0.57 x 10-3. M

Ml. base pR ^Oorr. n

1.000 2.48 0.16 13.23 1.480 2.60 0.25 12.88 1.980 2.75 0.42 12.45 log : k = 12.35 2.380 2.87 0.625 12.10 2.800 3.06 0.796 11.55 3.180 3.30 0.972 10.86 3.490 3.66 0.957 9.81 3.800 3.97 1.00 8.94 4.100 4.19 1.07 8.39

the total initial volume of 98.7 ml., A = 5 .06 x 10' CD = 4.71 x -3 -3 10 , C = 0.57 x 10 . Equal volumes of dioxane and 0.2001 N NaOH were added. 50 volume 70 dioxane. 35°C.

Table 139. Titration of anthranilic acid diacetic acid and zinc with = 1.14 x 10-3,

Ml. base pR pHCorr. n

1.000 2.49 0.07 13.17 1.490 2.56 0.17 12.91 1.990 2.69 0.29 12.60 log k = 12.31 2.500 2.80 0.525 12.30 3.000 2.91 0.65 11.99 3.490 3.08 0.705 11.50 4.000 3.30 0.967 10.88 4.400 3.74 0.99 9.62 5.000 4.22 1.05 8.31 5.200 4.35 1.05 7.98

the total initial volume of 98.7 ml., A = 5.06 x 10‘ CD = 5.08 x -3-3 10 , C,, = 1.14 x 10 . Equal volumes of dioxane and 0.2Q01 N NaOH were added. 50 volume ° /o dioxane. 35°C. 169 Table 140. Titration of anthranilic acid diacetic acid and cadmium with = 0.525 x 10”3.

Ml. base pR pHCorr. n

1.000 2.52 0.00 13.09 1.500 2.68 0.02 12.62 2.000 2.89 0.14 1 2 .0 1 log ; k = 10.68 2.400 3.13 0.26 11.30 2.790 3.34 O .48 1 0 .7 0 3.100 5.55 0.69 10.10 3.410 3.77 0.815 9.48 3.700 3.99 0 .9 0 8.87 4.000 4.19 1.28 8.36 4.320 4.38 1.14 7.87 4.600 4.52 1.12 .7.52

the total initial volume of 98.7 ml., A = 5.06 x 10'r 3 , C_ = 4.76 x -5 -3 10 , = 0.525 x 10 . Equal volumes of dioxane and 0.2001 II NaOH were added. 50 volume dioxane. 35°C.

Table 141. Titration of anthranilic acid diacetic acid and

cadmium with C,r = 1.05 x 10 M

HI. b a s e pH,, — dR Corr. n

1.000 2.49 0.08 13.23 1.510 2.65 0.07 12.76 2.000 2.85 0.12 12.17 log k = 10.84 2.500 3.06 0.24 11.56 2.890 3.22 0.38 11.11 3.300 3.39 0.58 10.63 3.700 3.60 0.73 10.05 4.100 3.85 0.86 9.36 4.520 4.15 0.945 8.55 4.800 4.33 1.00 8.09 5.100 4.54 1.01 7.60

In the total initial volume of 98.7 m l ., A = 5.06 x 10"3 , CR = 4.59 x -3 -3 10 , = 1.05 x 10 . Equal volumes o f dioxane and 0.2001 N NaOH were added. 50 volume dioxane. 35 C. DISCUSSION 170

Factors involved in chelate formation

In discussing the formation of chelates in 1949 Merritt (53) stated that the following factors might affect the formation and stability of chelate compounds:

(1) 'the presence in the molecule of the requisite acidic and basic groups.

(2) The position of these groups so that the various-sized rings may be formed.

(5) Steric effects, that is, hindrance by neighboring groups.

(4) The size of the ion, its charge and corresponding charge density.

(5) The distance between the "points" of the "claw" of the organic molecule.

(6) The affinity of the metallic ion for electrons.

(7) The base and acid strength of the groups of the organic molecule.

(s) The possibility of resonace in the chelate compound.

(9) The effect of the solvent, especially in the stabilization of the metal ion.

(10) A n y special spatial requirements of the metallic ion.

Since 1949 much data concerning the stability of chelate compounds have appeared. Usually when such data are presented an attempt is made to correlate it with some property or properties of the ligands and metal ions concerned. The success of such attempts depends in large part upon how well the above ten factors are understood and accounted for. Often, for a set of stability constants, most of the above factors have been held essentially constant, and the changes in the stability constants are related to one of the factors. The above ten factors will be discussed in relation to the five cations and thirteen ligands involved in this study. 171 Factor (l). The presence in the molecule of the requisite acidic and basic groups. Each of the compounds has at least one carboxyl group situated on a benzene ring. Only 2-(aminomethyl) benzoic acid (ix), salicylic acid (x), and 0-(carboxymethoxy)-benzoic acid (xi) do not have a nitrogen on the ring ortho to this carboxyl group. Of the ten remaining ligands, only anthranilic acid (i), has no substituent on that nitrogen. N-(aminoethyl)-anthranilic acid (VIIl) and 2-(aminornethyl)- benzoic acid (IX) have aliphatic amino groups. Salicylic acid (x) and o-(carboxymethoxy)-benzoic acid (Xi) contain no nitrogen, and were included for the purpose of assessing the relative abilities of oxygen and nitrogen to form chelate bonds in these types of ligands. 0-(carboxymethoxy)-benzoic acid (Xi), N-(carboxymethyl)-anthranilic acid (XIl), and anthranilic acid diacetic acid (XIIl) have carboxyl groups that are not situated on the benzene ring. Four of the ligands - anthranilic acid (i), N-methyl anthranilic acid (ll), 2-(aminomethyl)- benzoic acid (ix), and salicylic acid (x) - may be expected to act as bidentates and to give at least 2:1 complexes with all five metals. Three of the ligands - N,N' ethylene dianthranilic acid (Vi), N,N' trimethylene dianthranilic acid (VIl), and anthranilic acid diacetic acid (XIIl), may be expected to act as quadridenbates to give 1:1 complexes. The remainder of the ligands may be expected to act as tridentates, giving 2:1 complexes in some cases. Factor (2). The position of these groups so that the various-sized rings may be formed. The positions of the groups in the ligands are quite varied, and were so designed with the intent of studying the effects of ring size as related to stability. Except for 2-(aminomethyl)-benzoic acid (ix), the c;.r'ooxyl group on the ring lias an ortho nitrogen or oxygen atom on the benzene ring. These ligands may be expected to give chelates containing six-membered rings - including the cation. ethylene dianthranilic acid (Vi), h-(aminoethyl)- anthranilic acid (VIIl), o-(carboxymethoxy)-benzoic acid (XI), N-(carboxymethyl)-anthranilic acid (XIl), and anthranilic acid diacetic acid (XIIl) should also contain one or more five-membered rings. 2-(Aminomethyl-benzoic acid (ix) was included for the purpose of 172 investigating a seven-membered ring. N,N' trimethylene dianthranilic acid (VIl) should contain three six-membered rings for comparison with N,N* ethylene dianthranilic acid (Vi). Model studies and bond distances indicate that 2,2' hydrazo dibenzoic acid (iv) and methylene dianthranilic acid (v) cannot place both nitrogen atoms on the metal ion at the same time; therefore, these ligands are believed to be tridentate. In addition to the one six-membered ring, 2,2' imino dibenzoic acid (ill) should contain a second six-membered ring, 2,2' hydrazo dibenzoic acid (IV) should contain a seven-membered ring, and methylene dianthranilic acid (V) should contain a eight-membered ring. Factor (3). Steric effects. Steric hindrance among these ligands is difficult to estimate. Substitution of the nitrogen of anthranilic acid with a methyl group or with other groups should make a difference in the manner in which the ligand molecules can be attached to the metal ion. This difference should be one of the factors involved in variations observed among the formation constants of anthranilic acid and N-methyl anthranilic acid. Formation of the 2:1 complex of M-methyl anthranilic acid in a square planar configuration restricts the rotation of the methyl groups if the Hirschfelder models are correct. There are undoubtedly important steric hindrances among the tliree "short dianthranilic" acids, 2,2' imino dibenzoic acid (ill), 2,2' hydrazo dibenzoic acid (IV), and methylene dianthranilic acid (V). It is interesting that the Hirschfelder model of the 1:1 complex of (III) is very flexible and the ligand can be moved to many positions around the metal ion. The models of the chelates of (TV) and (v) are not at all flexible. The model of the 1:1 chelate of N,N' trimethylene dianthranilic acid (VIl) shows more difficulty in formation than does the 1:1 chelate of N,H' ethylene dianthranilic acid (Vi). Factor (4 ). The size of the ion, its charge and corresponding charge density. These are not very important considerations in the present work. +2 +2 The metal ions are all divalent. The radii of the series Co , Ni , +2 +2 Cu , and Zn are so nearly the same, that considerations of charge density differences are of no consequence. The situation is much the +2 +2 same when comparing Zn and Cd . As pointed out by Izatt, Femelius, and Block (54)5 1 7 5 2+ 2+ The Zn and Cd chelates are observed to have about the same order of stability and one cannot predict with certainty which will be the more stable with a particular ligand... A possible explanation for this lack of predictability lies in the fact that two opposing effects are present. In going from Zn^+ to Cd2+, the ionic radius increased by 0.20 i . This factor taken alone would cause Zn2+ to be the more stable. However at the same time the nuclear charge has increased by 18 units in the case of Cd&. This latter effect would result in a more stable Cd2+ complex. Apparently these two opposing effects are so balanced that compounds of similar stability result in most instances. Factor (5). The distance between the "points" of the "claw" of the organic molecule is another factor which is difficult to estimate. Most of the compounds can assume several spatial configurations. This +2 +2 factor could be decisive in those cases where the Zn and Cd chelates are observed to have a considerable difference in stability. Because of the flexibility of the ligands this is probably not a decisive factor in the series 2,2' imino dibenzoic acid (ill) through N,N' trimethylene dianthranilic acid (VIl). Factor (6). The affinity of the metallic ion for electrons is prob ably the most important property of the metal ion in the formation of these chelates. The second ionization potential has been used as a measure of this factor. These values as given by Herzberg (55) are Co, 17.4 v.; Hi, 18.2. v.; Cu, 20.28 v.; Zn, 17.96 v.; and Cd, 16.90 v. This alone would predict an order of stability: Cu^ Ni). Zn} Co} Cd. Harris did find this order for the chelates of sulfo Anthranilic acid (3 ), but not for etnylene dianthranilic acid. Johnston and Freiser (56) have explained why this correlation of log k and the second ionization potential is often valid. Each time this relationship is used it is implicitly assumed that only bond strength or a H is involved. Since the second ionization potential may be taken as a rough estimation of the average electron attracting power of a divalent metal ion it will also be a measure of the attracting power of that divalent metal ion for a source of electrons such as are found in the chelate ligand groups. Hence it is more nearly related to bond energy and H of chelation than to a F aa measured by the log of the chelate formation constant. Williams has recently pointed out that the ionization potentials do not compare strictly comparable states (57). 174 The ionisation potential is not a proper measure of the overall stability of a complex, for the latter includes two unrelated energy terms, the splitting of the d levels by an electrostatic field, and the directional character of d y cr and d y «r orbitals which increases or restricts covalency. Usually, however, changes in ionisation potential have sufficiently large influence to mask other factors. van Uitert, Femelius, and Douglas (5 2) have used the electronega tivities of the metal ions as a measure of the affinity of the metal ions for electrons. These values as given by Haissinsky (58) are Co 1.7, Ni 1.1, Cu 1.8, C u ^ 2.0, Zn 1.5, and Cd 1.5. This alone would predict an order of stability: Cu^Ni = Co^ Zn = Cd. This is the "normal" order. This matter of order will be discussed more completely below. Factor (7). The various acidic and basic groups mentioned in the discussion of factor (l) above do show some wide variations in acidic and basic strength. The nitrogens situated on benzene rings do not show any real tendency to protonate. Although N-(aminoethyl)- anthranilic acid was prepared as the dihydrochloride, its titration curve in Figure 26 shows that the first proton is strongly dissociated. The last proton dissociated from this compound comes from the aliphatic NH^ and has a pK& value of 9»45» A similar aliphatic -NH^ of 2-(aminomethyl)-benzoic acid has a pK value of 10.16. The pK values dr Si of the carboxyl groups situated on benzene rings range from 4.17 to 7.18 for the compounds (i) through (x). For compounds (Xi), (XIl) and (XIIl) it is not certain which proton dissociates first. Schwarzenbach and Willi (16) have published spectrochemical evidence that the proton of the specie HR~ of anthranilic acid diacetic acid is situated on the nitrogen. This does not necessarily indicate a high basicity for the nitrogen. The excellent possibility of hydrogen bonding resonance in the specie HR- among six equivalent, closely located, negatively charged oxygen atoms can account for the reluctance of this last proton to leave and the separation of pk and pk . a2 a3 The forces operating in the binding of a proton to the donor group of a ligand are similar to those between the donor group and 175 the metal ion. in a complex ion of the ligand. For this reason, provided that the other nine factors do not vary too much, plots of the acidity constant logarithms against the formation constant logarithms may be expected to give straight lines for a series of closely related ligands. It is not to be expected that plots of data for compounds having different types and numbers of donor groups will be straight lines. Irving and Mrs. Rossotti (59) have discussed these relations in recent articles. Among the compounds in the present work, no three are similar enough to make such a correlation valid. Factor (s). The significance of resonance in the compounds used in this work is not apparent. Factor (9). The effect of solvent in these experiments has been discussed above. The same solvent medium was used throughout. The difficulties involved in comparing data for different solvent media have been mentioned by Holmes and Crimmin (5 0): One point which emerges from the figures is that behaviors in water and dioxan-water are not exactly parallel...but it does serve to underline Irving's (60) warning that it may not be possible always to correlate conclusions drawn from experiments in different media, or to assume that findings in one solvent are always true for another.

Factor (lO). Spatial requirements of the metal ions. On the basis of electron configurations it is predicted that the spatial arrangements of the five metal ions would be as follows for "covalent" complexes having a coordination number of four.

Co dsp^ 2 square planar Mi dsp square planar Cu dsp2 square planar Zn sp5 tetrahedral Cd BP5 tetrahedral

Recently Livingstone (6l) has published data about the magnetic susceptibilities of some solid chelate compounds. He finds that, The complexes can be divided into classes: (a) those with moments corresponding to 'ionic1 or tetrahedral bonding (sp3) and (b) those corresponding to 'convalent' or square bonding (dsp2). The former contain oxygen as one of the ligand atoms of the chelate group, and the latter have sulfur, together with nitrogen, 176 sulfur or arsenic linked to the metal atom.

His data for the experimental magnetic moments of the nickel and cobalt complexes of anthranilic acid indicate that the bonding in both is of •2 the "ionic" tetrahedral (sp ) type. Recent papers by Busch (62, 63) point out that in many instances the most important factor in determining what spatial configuration a complex will assume is the size of the excitation energy required to transform the electronic configuration of the metal ion in its ground state to the configuration required by the bond hybrid in question. The larger this energy term becomes, the less likely it is that the energy gained by the formation of the complex in the hybrid bond form will be sufficient to cause the overall two-step process to proceed. For Co, Ni, and Cu with a coordination number of four, two 3 2 configurations are plausible: (sp ) tetrahedral and (dsp ) square- planar. A comparison of the angular bond strengths shows that the square planar is favored. However, its formation requires a change among the 3 d electrons; whereas the formation of the tetrahedral hybrid can proceed without changes among these 3 d electrons. For Co and Hi, the change needed is the rearrangement and pairing entirely within the 3 d level, and the excitation energies are 48.6 kcal. and 41.3 kcal respectively (62, 63, 64). With regard to nickel Busch (6 2) states: Since the value of P (which arises from the pairing of two electrons) is small...in the case of nickel (il), it is not surprising that relatively small changes in the nature of the ligand, or even changes in the solvent, may result in reversing the order of the stabilities of the paramagnetic and dimagnetic forms.

It seems reasonable that the behavior of cobalt for coordination number four should be similar. For copper, the rearrangement of 3 d electrons to achieve an excited electronic state suited to the formation of dsp^ hybrid bonds appears to require the promotion of one 3 d electron to a 4 p level and an excitation energy of 419 kcal (62,63,64)/mole. In spite of this, "The evidence accumulated on the structure of copper (il) complexes is overwhelmingly in favor of square planar 177 2 structures and, presumably, dsp bonding"(63). Busch (6 3) and Pauling (6 5) believe that no promotion has actually occured because the orbitals used before (3 d) and after (4 p) any proposed promotion are actually involved in the final hybrid bond orbitals (dsp ). All three 4 P orbitals take part in the hybridization, and the result is that no excitation energy is required to achieve the electronic state suited to the hybrid orbitals. To achieve the electronic state suited to a coordination number 2 3 of six with d sp hybrid bond orbitals, cobalt (il) requires the promotion of one 3 d electron to the 5 s level, a process requiring 580 kcal/ mole. This promotion is a very unlikely event. Nickel would require the promotion of two 3 d electrons, and copper three. These events are even more unlikely. Six-coordination for these three cations 3 2 can also occur in the formation of the sp d octahedral outer orbital type of hybrid. As is also true for zinc and cadmium, this involves the metal ions in their ground states. Busch (63) states, it is apparent that the fact that the angular bond strength is always a 2 3 3 2 2 maximum in d sp hybridized bonds over sp d and in dsp hybridized 3 bonds over sp bonds...is not a sufficient condition to guarantee that such configurations will always be realized." Based on the above discussion, the following statements describe the spatial requirements of the five metal ions, Co (il), Ni (il), Cu (il), Zn (II), and Cd (il). 3 2 (1) Cobalt and nickel may either sp tetrahedral or dsp square 3 2 planar when four-coordinate, and both become sp d octahedral when six-coordinate. (2 ) Copper, because of its high electronegativity, shows a 2 pronounced tendency to be dsp square planar wnen four-coordinate and a reluctance to become six-coordinate. (3 ) The tendency to form the square planar dsp hybrid bonds decreases in the order Cu^>Ni^Co. •7 (4) Zinc and cadmium are sp tetrahedral when four-coordinate 3 2 and sp d octahedral when six-coordinate. (5) The requirements of the ligand have a large effect in the determination of the spatial arrangements of all five metal ions. 178

Table 142. Acidity constants in 50 volume jo dioxane

Number Name ^ a ^ a al 2

(1) Anthranilic acid 6.66 (2) N-methyl anthranilic acid 6.68 (3) 2,2' Imino dibenzoic acid 6.05 7.02 (4) 2,2' Hydrazo dibenzoic acid 5.99 6.80 (5) Nethylene dianthranilic acid 6.36 6.82 (6) Ethylene dianthranilic acid 6.53 7.18 (7) N,N' Trimethylene dianthranilic acid 6.45 7.17 (8) N-(Aminoethyl)-anthranilic acid dihydrochloride <2 5.54 (9) 2-(Aminomethyl)-benzoic acid hydrochloride 4.17 10.16 (10) Salicylic acid 4.45 (11) o-(Carboxymethoxy)-benzoic acid 4.05 7.06 (12) N-(Carboxymethyl)-anthranilic acid 5.44 6.96 (13) Anthranilic acid diacetic acid 4.49 5.30

At ionic strength 0.1 (KNO^), the values below were obi

(7) N,N’ Trimethylene dianthranilic acid 6.10 6.78 (9) 2-(Aminomethyl)-anthranilic acid hydrochloride 4.14 9.99 Table 143. Log k values of the chelates in 50 volume $ dioxane

(l)* (2)* (3) (4) (5) o l O CO I Tj CD I 1—I *H ’H £ *H P. I >,1 0 O TJ » O 0) w-, CO ^ 5 0 M N t>>rQ<3 rH ,cj jd -H CD ,3 -H ncJ - 0) -O - £1 q .ff 3 -H *8 +» rH tH JSJ +» rH -H CM ,Q -H CM *rl +» Cd i—I 'H q-HO 1 O'H O - - H O *00 J2 T* 'd 9 -=33-a) a -3 R <1 CM fi<| CM N N g fl H 4

Copper log kx 5.05 4.35 8.05 7.85 7.45

(log k][k2)/2 4.60 4.05

log k2 4.15 3.70

Kiokel log 3.20 3.05 5.45 3.85 3.75

(log k^kp/2 2.85 2.85

log k2 2.50 2.65

Cobalt log 2.85 2.95 5.10 3.85 3.50

(log ^kgJ/2 2.80 2.80

log k2 2.75 2.65

Zinc log kx 2.6 3.3 5.55 4.60 3.85

(log k.jk2)/2 2.90 2.9 log k2 3.2 2.5

Cadmium log k^ 3.05 3.3 5.75 4.70 4.40

(log k ^ / 2 2.70 3.0

log k2 2.3 2.7

* The formation constants for copper and cadmium with anthranilic acid and N-methyl anthranilic acid were determined by Harris (l, 4). The values given here have been convergence corrected. oat o k .5 .0 .5 .5 .8 5 4.55 5.95 5.00 6.45 k log Cobalt K o IS! EEJ o (D p H* H- o 4 P O o (D i* O IV o M H H ro H ro a- o O O 4 CD H (4 OP o H CP H CP H

VJI VJI VJI o VJI o VJI o O VJI ionic strength = 0.1 ro 180 o 13.00N 6.75 5.85 o 1.9 Nickel log k o f» H- o o 3 o' 3 £ o 3 3 M M M CD o O o O o H 0*3 Cto I—1 0*3 0*3 03 t-3 o o o o M o o (B Ot} 0*3 tv 0*3 01} tv O 0*3 tv 0*3 !V O cr1 M 01} I—1 m r—> tv *"V . tv tv tv !V

ro ro to r o ro 03

0*3 t v N> ro V^3 ro r o f o ro ro ro V>4 ro IO ro to • • • • •• • • •• • . Salicylic M ro 0 3 VO VJI ro —3 o H VJI -0 oo VO o VJI O VJI VJI VJI VJI VJI Acid £ £ 0}CD O o—(carboxymethoxy) • H, cr\ ov • benzoic »-> C+- -p. oo -0 VJI i—1 3 " o o VJI o Acid CD o tv I-1CD ro VJI VJI ro VJI V» -p* VJI VJI N-( carboxymethyl) - 3 • • • •• • -p. VO c+ •• •• M CD VO —*3 H Cv o Ch r—1 Vj 3 “O H- CJ\ anthranilic ro 0 3 o VJI o VJI VJI O VJI o VJI o o VJI o VJI acid H- 3 VJI o H Anthranilic acid O IO • diacetic M 3 03 oo Vji 0 3 VJI O VJI o acid (D

£ O

CD 181 182 Table 144. Orders of log for the five cations

Compound No.

(I) Cu Ni Cd Co Zn

(II) Cu Cd Zn Ni Co

(III) Cu Cd Zn Ni Co

(IV) Cu Cd Zn Ni Co

(V) Cu Cd Zn Ni Co

(VI) Cu Ni Co Zn Cd

(VII) Cu Ni Cd Zn Co

(VIII) Cu Ni Co Zn Cd

(IX) Cu Ni Zn Co Cd

(i x ) I.S.= 0.1 Cu Ni Zn Cd Co

(X) Cd Cu Zn Co ? Ni

(XI) Cu Zn Cd Ni Co

(XII) Cu Ni Co Zn Cd

(XIIl) Cu Ni Zn Co Cd 183

Discussion of results»

A comparison of the formation constants of zinc and cadmium chelates verifies the statements of Izzatt, Femelius, and Block (54). In six cases the 1:1 chelates of zinc are more stable, in six the chelates of cadmium are more stable, and in one case the constants are the same. For only three of the thirteen ligands - N,N' ethylene dianthra nilic acid (Vi), N-(aminoethyl)-anthranilic acid (VIIl), and N-(carboxymethyl)-anthranilic acid (XIl) - is the complete "normal" order Cu> Ni> Co> Zn> Cd observed. Omitting cadmium from the series adds only anthranilic acid to the three ligands which already follow the order Gu> Ni> Co> Zn. For the remaining nine ligands zinc exceeds either cobalt, or both nickel and cobalt, in order of stability. In the published data that is available quite a few instances can be found where the complete "normal" order is not maintained. It is important to note that for all thirteen ligands the order of stability of the 1:1 chelates is Co Zn. This is the Irving-Williams order (66) which is generally accepted as being valid for all ligands. The com plete "normal" order has been found for many of the ligands investi gated by van Uitert, etal (47, 48, 51» 52, 67). The order Cu> Ni> Co> Zn has been observed in many investigations (47, 48, 51, 52, 67, 68, 69). The orders of stability of the 1:1 chelates of ligands - N-methyl anthranilic acid (il), 2,2’ imino dibenzoic acid (ill), 2,2' hydrazo dibenzoic acid (IV), and methylene dianthranilic acid (v)— are the same: Cu > Cd>Zn> Ni> Co. For each of the five cations the order is (lll)> (IV)> (v)> (il). Among the quadridentates - N,N* ethylene dianthranilic acid (Vi), N,N* trimethylene dianthranilic acid (VIl), and anthranilic acid diacetic acid (XIIl) -, the order for all five metal ions is (XIII)> (Vi)> (VIl); even though the order of the five metal ions is different

2 Salicylic acid is apparently an exception. Note that only 0.1 log units of difference of k^'s causes the reversal of nickel and cobalt. This is less than the uncertainty of these constants. 184 for each ligand. For the zinc chelates of antiiranilic acid (I), 2-(aminomethyl)- benzoic acid (IX), and salicylic acid (x), the second ligand molecule shows greater tendency to become attached than does the first. This may be because the 2:1 chelate is symmetrical, and hence favored, whereas the 1:1 chelate is not. It should be noted that the donor groups of all three ligands are unsubstituted; whereas the remaining ten ligands have substituted donor groups. The log k^ values for anthranilic acid (l) show a "normal" trend except for the position of cadmium. The stability constants k^k^ show a "normal" order except for the position of zinc. The addition of the methyl group to anthranilic acid (i) to give N-methyl anthranilic acid (il) is believed to bring about two important changes as far as chelation is concerned. First, the electron donating property of the methyl group should in turn make the nitrogen atom a better electron donor in the formation of chelates. This should cause an increase in the sizes of the formation constants. Second, steric effects of the methyl group may be expected to make it more difficult for N-methyl anthranilic acid ligand molecules to fit around metal atoms, as compared to the ability of anthranilic acid ligands. The results would indicate that the two factors tend to offset each other for the chelates of nickel, cobalt, and zinc. Apparently the first factor is of more importance for cadmium, and the second of more importance for copper. The fact that the log k values of 2,2' imino dibenzoic acid (ill) are more than 1.5 times the log k^ values of anthranilic acid (i) indicates that the carboxyl group is probably a considerably better electron donor group than is the aromatic nitrogen in the formation of these chelates. Possibly the order Cu> Cd> Zn>Ni> Co for the chelates of 2,2' imino dibenzoic acid (ill) is the result of difficulties of this 2 ligand in attaining a configuration suited to the dsp square planar hybrid bond orbitals for Cu, hi, and Co. The lesser stabilities of the chelates of 2,2* hydrazo dibenzoic acid (iv) and methylene dianthranilic acid (v) as compared to those of 2,2' imino dibenzoic acid (ill) probably result from increased steric 185 hindrances and lesser flexibilities of the ligands and complexes. The structures of 2,2' hydrazo dibenzoic acid (IV) and methylene dianthra nilic acid (V) are apparently quite unfavorable for formation of chelates with nickel and cobalt. The “normal" complete order for N,N* ethylene dianthranilic acid (VI) is likely the result of a relatively unstrained and unhindered ligand. The fact that the complex of nickel is considerably more stable than that of cobalt is believed to be the result of a special favorability of the five-membered chelate ring containing an ethylene bridge for nickel. This same effect is observed for N-(aminoethyl)- anthranilic acid. The chelate effect is a term which has been introduced and dis cussed by Schwarzenbach (70). It is a comparison of the log k values of the chelates of ligands containing several donor groups with the log k values for simpler ligands containing the same donor groups. To make a fair comparison, the same number and types of donor groups must be included. In the present work it is appropriate to compare the log k values of N,N' ethylene dianthranilic acid with the logarithms of the stability constants (i.e., log k^k^) of the 2:1 complexes of anthranilic acid and N-methyl anthranilic acid. By definition, Chelate effect = log kj. A_A>- log ^

Table 145 shows the chelate effects of N,N* ethylene dianthranilic acid. 186 Table 145. The chelate effect of N,N* ethylene dianthranilic acid

Cu Hi Co Zn Cd

Log k for di A.A. 10.25 8.56 6.45 6.08 6.05

Log kjk,, for A.A. 9.20 5.70 5.62 5.82 3.56

Chelate Effect +1.05 +2.86 +0.83 +0.26 +0.69

Log k for di A.A. 10.25 8.56 6.45 6.08 6.05

Log k^k2 for W-CH^AA 8.06 5.78 5.60 5.80 5.96

Chelate Effect +2.19 +2.78 +0.85 +0.28 +0.09

Copper, and especially nickel, show considerable increased stability. The ethylene bridge effect in the case of nickel is again demonstrated. Statistical effects alone would predict a chelate effect of 0.3 log units, and zinc and cadmium average just about that.

Table 146. The chelate effect of K,N* trimethylene dianthranilic acid

Cu Hi Co Zn Cd Log k for di A.A. 8.10 5.43 5.00 5.18 5.28

Log for A.A. 9.20 5.70 5.62 5.82 5.36

Chelate Effect -1.10 -0.27 -0.62 -0.64 -0.08

Log k for di A.A. 8.10 5.43 5.00 5.18 5.28

Log kjkg for W-CHj A.A. 8.06 5.78 5.60 5.80 5.96

Chelate Effect +0.04 -0.35 -0.60 -0.62 -0.68

Here the chelate effects are all appreciably less than the 0.3 log unit's statistical factor. The six-membered ring' containing the propylene bridge is so unfavorable that the ligand has less tendency 187 to form the quadridentate chelate than do two anthranilic acid or N-methyl anthranilic acid bidentate ligands. The chelate effects are not appreciably different in the case of nickel. Table 145 shows that the chelate effects of N , W ethylene dianthranilic acid compared to anthranilic acid and to N-methyl anthranilic acid are about the same for nickel, cobalt, and zinc. For cadmium and copper the chelate effects compared to anthranilic acid and N-methyl anthranilic acid are consider ably different. Table 146 shows the same situation for N,N' trimethyl ene dianthranilic acid. The differences in the case of copper are again an indication of the steric difficulties of the N-substituted methyl group with copper. The differences in the case of cadmium are possibility an indication of the increased basicity of the nitrogen where the methyl group does not +2 cause as many steric difficulties, since Cd has a larger ionic radius. For N-(2 aminoethyl)-anthranilic acid the "normal" C\i)> Ni)> Co)>Zn^> Cd order is observed. As mentioned above, the ethylene bridge is present, and the nickel chelate is considerably more stable than the cobalt chelate. Two-to-one chelates are indicated by the data for each of the metal ions. This would indicate a coordination number of six, the ligand being assumed to be tridentate. The large difference between k^ and for copper is one of two instances of such behavior in the present work. This means that the chelation steps are well separated in the case of copper, and is in agreement with the idea that four is the favored coordination number for copper. Similar behavior has been noted between the 2:1 and 5:1 complexes of ethylene diamine and copper (7l). The zinc chelates of N-(aminoethyl) anthranilic acid are considerably more stable than the cadmium chelates. As compared to anthranilic acid, 2-(aminomethyl) benzoic acid involves two major changes. The amino nitrogen becomes much more basic, and the chelate ring becomes seven-membered. The first change should result in increased stability of complexes; the second should have the opposite effect. The overall result was a reversal in the positions of zinc and cadmium in the stability orders and a general increase in the size of the constants. This increase in the size of the constants is, however, more than offset by the increased proton affinity of the _ 188 nitrogen. The result is that comparable values of n occur at higher pH's for 2-(aminomethyl) benzoic acid. Accordingly any analytical application of this compound would require the use of more basic solutions than would anthranilic acid. This is not a desirable proper ty. Salicylic acid was included in the present work for purposes of comparison with anthranilic acid. The pk& value for the phenolic proton is likely to exceed 13 (72) in the present solution medium, and its measurement is not easily accomplished. Uncertainty regarding ionic strength and the formation of alkali metal complexes would arise. For these reasons no provision was made for the dissociation of the very weakly acidic phenolic hydrogen in the derivation of the equations used to calculate the formation constants. It has been assumed that the complexes are formed with the anion HSal . This appears reasonable because of the large number of pH units separating the region where complex formation occurs and the region where the phenolic proton normally becomes dissociated. Some of the n - pR data at higher pH's indicate that the above assumption may not be entirely correct. The result of this would be that the measured formation constants would tend to be too high. The formation constants given for salicylic acid are probably less accurate than those given for the other ligands. Except for cadmium, the present data indicate that anthranilic acid forms more stable complexes than salicylic acid. The greater electronegativity of the phenolic oxygen as compared to the amino nitrogen is also indicated by the difference of 2.2 log units in the pK values of the carboxyl groups. £1 The above conclusion regarding the relative electron-donor properties of the ring-situated oxygen is substantiated by a comparison of the formation constants of 0-(carboxymethoxy)-benzoic acid (Xi) and N-(carboxymethyl)-anthranilic acid (XIl) for copper and nickel. However, it is seen that the complexes of the all-oxygen ligand (Xi) with zinc, cadmium, and cobalt are more stable than those of (XIl). It seems significant that the largest differences occur with zinc and cadmium. This is in agreement with the idea that the zinc and cadmium ions have a completed d shell and tend to form outer orbital complexes 189 of a more ionic nature. The salicylic acid data indicate the same thing. It is also significant that there is a considerably greater spread among the log k values for the five cations with h-(carboxymethyl) anthranilic acid (XIl) than with o-(carboxymethyl)-benzoic acid (Xi) The effect of adding acetic acid groups to the nitrogen is seen in the series anthranilic acid (i), N-(carboxymethyl)-anthranilic acid (XIl) and anthranilic acid diacetic acid (XIIl). This is seen in Table 147.

Table 147. Log k^ values of three acids with the five cations,

Cu Ni Co Zn Cd Anthranilic acid (I) 5.05 3.20 2.85 2.6 3.05 N-(carboxymethyl)-A.A., (XII) 9.65 6.75 5.65 5.60 5.10 A.A. diacetic acid (XIIl) 14.30 13.00 11.85 12.30 10.75

For the first four metals, the increase in k^ from anthranilic acid (i) to anthranilic acid diacetic acid (XIIl) is between nine and ten log units. For copper the increase between anthranilic acid (l) and N-(carboxymethyl)-anthranilic acid (XIl) is about the same as the increase between ¥-(carboxymethyl)-anthranilic acid (XIl) and anthra nilic acid diacetic acid (XIIl); but for the remaining four metal ions the increase in stability resulting from the addition of the second acetic acid group is considerably larger than that resulting from the addition of the first. This relative reluctance on the part of copper 2 is oelieved to indicate that copper is dsp square planar and is less 3 ready than nickel or cobalt to assume the sp tetrahedral form which is already the configuration of zinc and cadmium. The Hirschfelder model indicates that the donor groups of anthranilic acid diacetic acid (XIIl) cannot be arranged to a square planar structure. This same type of reluctance is seen in the large separation of and k^ for the chelates of copper and w-(carboxymethyl)-anthranilic acid, l'ue 2:1 chelate requires that copper have a coordination number of six, assuming that the ligand is tridentate. This reluctance of copper 2 3 2 to go from dsp to the "outer orbital" sp d was mentioned in the discussion of Factor 10 on page 170. 190 T&e order of the stability of the chelates is different for each of the ligands listed in Table 147, and only N-(carboxymethyl)-anthranilic acid (XIl) has the "normal" N i ^ C o ^ Zn)» Cd order. The order of stabilities is the same for the chelates of N-(aminoethyl)-anthranilic acid (VIIl) and N-(carboxymethyl)- anthranilic acid (XIl). Figure 36 shows a comparison of the log k^ values of these two tridentates. The same order was found for N,N' ethylene dianthranilic acid (Vi). Figure 37 compares this ligand with N-(aminoethyl)-anthranilic acid (VIIl). For both figures, the points fall reasonably close to a 45° line, except for the position of cadmium. The reason for this divergence is the relatively low stability of the chelates of cadmium with N-(aminoethyl)-anthranilic acid (VIIl). This divergence of cadmium does not appear in Figure 38 where ethylene dianthranilic acid (Vi) and K-(carboxymethyl)-anthranilic acid (XIl) are compared. Figure 39 compares the log k values of N,N' ethylene dianthranilic acid (Vi) with those of W,K' trimethylene dianthranilic acid (VIl). The position of nickel again points out the special favorability of the five-membered chelate ring containing nickel and the ethylene bridge. Two ligands, 2-(aminomethyl)-benzoic acid (ix) and anthranilic acid diacetic acid (XIIl) have log k^ values in the same order as the second ionization potentials of the five metals. Data for these are graphed in Figures 40 and 41 respectively. 191

10.5 Cu

9.5

8.5

7.5 log k(A)

6.5

/Co 5 .5 - Zn

4 .5 -

3.5 Cd

5.0 6 0 70 8.0 9.0 10.0 11.0 log k(B)

FIGURE 36. LOG k(A) OF N-(AMINOETHYL) - A NTH R ANILIC ACID AGAINST LOG k(B) OF N(CARBOXYMETHYL)- ANTHRANILIC ACID 192

/ 10.5 Cu

9.5

8.5

7 5 log k(A)

6.5

5.5 Zn

4.5 -

3.5 Cd

5.5 6.5 7.58.5 9.5 10.5 log k (B)

FIGURE 37. LOG k(A) N - (AMINOETHYL)-ANTHRANILIC ACID AGAINST LOG k(B) N,N' ETHYLENE DIANTHRANILIC ACID 193

10.0

9.0 log k{A)

7.0

6.0 o / 0Zn Cd

5.0 5.0 6.0 7 0 8.0 9.0 10.0 II .0 log k(B)

FIGURE 38. LOG k(A) OF N.N1 ETHYLENE DIANTHRANILIC ACID AGAINST LOG k(B) OF N- (CARBOXY M E TH YL) ■ ANTHRANILIC ACID 194

Cu 10.0

9.0

8.0

7 0

Co Zn 6.0

5.0 LI 5.0 6.0 7.0 8.0 9.0 10.0 log k (B)

FIGURE 39. LOG k(A) OF N,N* ETHYLENE DIANTHRANILIC ACID AGAINST LOG k(B) OF N,N' TRIMETHYLENE DIANTHRANILIC ACID 195

21.0

Cu 20.0

19.0

iao Zn

Co 17.0 Cd

3.0 4.0 5.0 6.0 7 0 8.0 log k i

FIGURE 40. SECOND IONIZATION POTENTIALS VS. LOG k, FOR 2(AMIN0METHYL)-BENZOIC ACID CHELATES 196

21.0

Cu 20.0

9.0

2nd IP. 18.0 Zn

Co 17.0 Cd

16.0 10.0 11.0 12.0 13.0 14.0 150 fog k i

FIGURE 41. SECOND IONIZATION POTENTIALS VS. LOG k, FOR ANTHRANILIC ACID DIACETIC ACID CHELATES 197 Properties and analytical uses of the compounds.

(i) Anthranilic acid has been well developed as a precipitating agent for a number of metals, including the five in this study. The order of stabilities of the chelates of anthranilic acid in the 50 volume p dioxane medium used here is not the order of the pH of predipitation data as found by Harris (l) and by Goto (2 ). The order of precipitation parallels the order of the solubility of the anthranilates as measured in 1 M. acetic acid by Treadwell and Arnmann (73)• There is no clear relationship between the solubilities and the stabilities of these metal anthranilates. (ll) An attempt was made to use U-methyl anthranilic acid as a precipitating agent using solutions adjusted to pH 5*3 and two and one-half hours of digestion on the steam plate. The only apparent reaction was with copper which gave a green color. This reaction was investigated in the hope of developing a new colorimetric method for copper. The intensity of the color developed increases upon heating, but no plateau could be found in a curve of extinction against time of heating. Although other met-'Is do net produce any appreciable interforing color in the presence of copper; the extinction of the copper color is diminished because the interfering metal ions do remove part of the excess N-methyl anthranilic acid. This ob servation is in agreement with calculations made using acidity and formation constants. This interference cannot be alleviated by using a larger excess of reagent bee.: use of the limited solubility of the reagent in water. (ill) 2,2' Imino dibensoic acia also forms metal chelates which are relatively soluble in water. Precipitates were not formed during the chelation titrations, and Salyer (if) did not obtain a cobalt precipitate in his solubility studies in aqueous media. This compound might find some use as a masking- agent in an application where its sine of formation constants is appropriate. The closeness of the constants for Zn, Cd, Co, and hi should limit such uses. This compound has had one application which is not related to to ability to form complexes. Kirsanov and Cherirassof (19) and later Hillard 198 and hanola (20) described its use as an oxidation-reduction indicator. The first authors used it in 16 to 20 1J sulfuric acid solutions, and found that it did not function in hydrochloric acid. They found that the oxidizing agent must be as strong as I^Cr^Oand that the color change is reversible. The studies of Willard and Manola were made in basic solutions, where it seems likely that complex foimation could also have been involved. (iv) 2,2' Hydrazo dibenz oic acid complexes are also quite soluble in water. The low degree of stability of the chelate compounds is not favorable for most applications. Further, the possibility of rearrangement to a benzidine type of compound (3 2 , 33,34) during boiling in hydrochloric acid solutions is not particularly desirable. (v) Although methylene dianthrunilic acid complexes lack stability, and the reagent decomposes and rearranges when it is heated in aqueous solutions (36), some preliminary work indicated that the reagent might be used as a precipitating agent. A number of precipitation studies were made using procedures very similar to those used by Harris (l) in his precipitation studies of anthranilic acid. One hundred fo precipita tion of Cu, Co, Zn, and Ni could not be obtained. Cadmium was not studied. The procedure in which acetate buffer at pH 4.5, five hours of digestion on the steam plate, and hot filtration were used resulted in the precipitation of only about 85^ of the cobalt and nickel. These answers are in agreement with Salyer's observation that about 15% of the radioactive cobalt remained in the filtrate in similar experiments. Changing the amount of buffer to a very minimal amount of acetate raised the percentages of Co and Cu to about 98.5 and Zn to about 92.5 at pH 5.0. Omitting the acetate entirely, allowing the precipitate to digest at room temperature, and filtering at room temperature at pH 5.0 led to inconsis tent and low results and to end point difficulties for Cu, Ni, and Zn. Poorer results were obtained under similar conditions at pH 3 for Cu, Ni, and Zn. All of these results can be explained as follows: upon being heated, the methylene dianthranilic acid is decomposed or rearranged rapidly to compounds which do give metal ion precipitates. This process is much slower and less complete when heating is not used. In either case - using the procedures mentioned above - some methylene dianthranilic 199 acid remains unchanged and is able to form soluble complexes with the metal ions. It seems likely that by a proper variation of the conditions, a procedure could be developed for the quantitative precipitation of metal ions using methylene dianthranilic acid; however it seems also likely that such a procedure would offer nothing better than anthranilic acid as far as pH ranges, selectivity, convenience, and speed of operation are concerned. Another important consideration is that anthranilicacid is much more water-soluble than is methylene dianthranilic acid. Precipitates of methylene dianthranilic acid with cobalt and with copper were prepared in two ways. First precipitates were prepared using a one and one-half hour period of digestion on a steam plate. Second precipitates were prepared using a one and one-half hour period of digestion at room temperature. The precipitates were removed by filtra tion and were dried in a vacuum oven. The filtrate in each case had color indicating that precipitation of the copper or cobalt was not complete. The dried precipitates were analyzed for cobalt or copper using the titration procedures described by Harris (l). The percentages of copper and cobalt found in those precipitates that were digested on the steam plate indicate that the composition is two moles of anthranilic acid per mole of metal. The percentages of copper and cobalt found in those precipitates that were digested at room temperature indicate a composition of one mole of methylene dianthranilic acid per mole of metal. This is in agreement with the fact that heating in acidic aqueous solution causes methylene dianthranilic acid to decompose to anthranilic acid and formaldehyde (36). However, two pieces of evidence that do not support the above conclusion have been found. First, the infrared spectrum of the copper precipitate produced at room temperature is identical in every detail to the spectrum of the precipitate produced on the steam plate. The same is true for the cobalt precipitates. Second, the cobalt precipitate which Salyer (l2) produced with methylene dianthranilic acid using hot digestion had a considerably different water solubility than the cobalt precipitate with anthranilic acid using hot digestion. 200 (Vi) N,l’J' Ethylene dianthranilic acid was prepared and investi gated by Harris (l). Neither his work nor that of Salyer (12) have indicated analytical applications of this compound. (VII) N,N' Trimethylene dianthranilic acid is similar to N,N* ethyl ene dianthranilic acid. Its negative chelate effect has been noted on page 186« (VIII) The complexes of N-(aminoethyl)-anthranilic acid are water-soluble. This reagent developes a bright orange-yellow color with ferric ions even below pH 2. Nickel, copper, and both valence states of cobalt develope colors of much less intensity. Higher pH values are required to develope these colors® A preliminary study indicated that this reagent can be used for the spectrophotometric estimation of final iron concentrations in the range of 4 to 100 parts per million.' The study indicates that a pH of about 3 should be quite satisfactory and that nickel, copper, and cobalt should show very little interference if the absorption measurements were made a t 430 m. p. or above. (IX) 2-(Aminomethyl)-benzoic acid was tested and would not produce precipitates with iron or any of the five metals included in this study. As compared to anthranilic acid, t;is indicates that not only must the amino group be primary, but also it must be situated directly on the same benzene ring to produce insoluble chelates. In this connection it should be profitable to study 0-amino phenyl acetic acid to see what the effect of removing the carboxyl group from the benzene ring is. (X) No analytical applications of salicylic acid have been suggested by the present work. (XI) The same can be said for o-(carboxymethoxy)-benzoic acid. The smaller spread of the formation constants of this compound as com pared to those of N-(carboxymethyl)-anthranilic acid has been mentioned on page 189. (XII) Datta and Banerjee (l3) have developed a precipitation procedure for quadrivalent thorium using N-(carboxymethyl)-anthranilic acid. It seemed possible that the neutral 1:1 complexes of the five metals in this study might also be insoluble. Experiment showed that this is not true. The 2:1 complex of thorium would be chargeless, but 2:1 complexes of divalent cations would not. 201 (XIIl) The complexes of anthranilic acid diacetic acid are soluble, and they are more stable than those of any of the preceding twelve compounds. Fitch and Russell (l8) tested this ligand as an eluent for rare earths absorbed on an ion exchange column. They found that it was less satisfactory for this purpose than nitrilo triacetate. The complexes of anthranilic acid diacetic acid are sufficiently stable that the acid may be used in titration procedures for the estimation of the metals. These procedures have been covered by Schwarzenbach and were patented by him (l4, 17). Because anthranilic acid diacetic acid has the largest formation constants of any of these compounds, its color reactions were studied in more detail than were some of the other compounds. The cobalt (il) complex i3 pink and has an absorption maximum at 525 m. jr. The molar extinction coefficient at this wavelength is 17.3. The complexes of zinc, cadmium, copper, and nickel do not absorb at this wavelength, but the yellow complex of ferric iron has an extinction curve which rises steeply in this region. Attempts to measure this yellow iron color in the ultra violet using the reagent as the blank were not successful because of the fluorescence of the reagent. Attempts to mask the yellow iron color with fluoride ion -were not successful because precipitates believed to be salts of the complex ferric fluoride appeared and because a serious decrease in the intensity of the cobalt color also occured. Addition of hydrogen peroxide to solutions containing cobalt and anthranilic acid diacetic acid leads to a deepening of the pink color. This color becomes very dark within two hours time, especially as the concentration of cobalt approaches 0.01 M. and as the pH is increased toward seven. Heating accelerates the darkening and makes it very sensitive to small amounts of metals. In particular, cobalt and iron were found to initiate the reaction. A good many variables were found, including the type of metal ion, concentration of metal ion, time, pH, and temperature. These are not independent variables, and the reaction was found to be difficult to reproduce exactly. Using a pH of 7 and one-half centimeter cells for measurement, a lower concentration limit of 0.1 p.p.m. 202 of cobalt was estimated. The reaction of iron appears to be at least as sensitive, and is much more rapid than that of cobalt which requires at least one hour for complete color development at boiling temperature. Copper is much slower. 203

Summary

The formation constants for the chelation reactions of anthra nilic acid and N-methyl anthranilic acid with the divalent cations of cobalt, nickel, and zinc have been determined. These data have been compared to similar data previously given for the reactions of the same organic acids with copper and cadmium, and for ethylene dianthranilic acid with cobalt, nickel, and zinc. The pH of precipitation curves for these five cations with anthra nilic acid measured by Harris are more closely related to the solubilities of the chelates than to their solution stabilities. Four "dianthranilic acids" have been prepared, measured, and compared to anthranilic acid, N-methyl anthranilic acid, and ethylene dianthranilic, acid. The results of the comparisons have been discussed in terms of such factors as the number of donor atoms, size of the chelate rings, steric effects of the ligands, and bonding properties of the cations. 2-(Aminomethyl)-benzoic acid has been prepared and studied for the purpose of finding out the result of removing the amino group of anthra nilic acid from the benzene ring. Although the complexes do have larger formation constants; this factor is offset by the greater proton affinity of the amino group. The chelates are considerably more soluble in water than are those of anthranilic acid. Approximate data have been given for the reactions of the KR~ anion of salicylic acid with the five cations. Except in the case of c. dmium, anthranilic acid forms chelates of greater stability. The f'avorabiiity of the five-membered cnelate ring containing nickel and the ethylene diamine structure previously observed for ethylene dianthranilic acid lias been substantiated in the present work with IJ-( ami no ethyl) -anthranilic acid. Data for M-( c.vrboxymethyl)-anthrani 1 ic acid and o-(c: .rvoxymethoxy)- benzoic acid -how th-t the all-oxy.;en-donor lie;, no forms stronger complexes with zinc and cadmium and with cobalt to a lesser extent. This is in agreement with the postulate that the greater electro negativity of oxygen as compared to nitrogen favors the more "ionic" 204 3 3 2 bond hybrids, sp and sp d . Comparison of formation constants of anthranilic acid, il-(carboxymethyl)~anthranilic acid, and anthranilic acid diacetic acid show the progressive increases in chelate stabilities resulting from the addition of acetic acid groups to the amino group of anthranilic acid. These data confirm the information gained by a study of the Hirschfelder model of anthranilic acid diacetic acid. This showed that the structure of the ligand is such that it can not arrange the four donor atoms into a planar configuration. The result is that all five cations are forced to assume a tetrahedral configuration. Thi3 idea is supported by the fact that the sizes of the formation constants have the same order as the second ionization potentials of the metals. Previous statements that five-membered chelate rings are more stable than six-membered have been confirmed by comparison of the present data for 11,11' trimethylene dianthranilic acid with that for ethylene dianthranilic acid. Among the thirteen ligands, only one of low experimental accuracy (salicylic acid) violated the very generally observed order of stability of the 1:1 complexes, Zn Ei > Co, which is the Irving - Williams order. Preliminary experiments indicated that one of the compounds, N-(ai:iinoet.;iyl)-anthranilic acid, could be used as a colorimetric reagent for iron. The more important nitrogen is as a donor atom, the more "convalent" the bonding is, and the more the spread of the formation con stants for a series of cations. Solubility is a more importairt consideration in the development of selective or specific reagents than are solution stabilities of the complexes. The present work indicates that substitution of the amino group of anthranilic acid produces compounds that form metal chelates with a higher water solubility than those of anthranilic acid. Separation of the amino group from the ring by a methylene group has a similar effect. 205 Appendix

(ill) Preparation of 2,2' imino dibenzoic acid. Twenty grams of the potassium salt of 0-chloro benzoic acid and 14.8 g. of anthranilic acid were dissolved in about 60 ml. of n-amyl alcohol at the boiling point. To this were added 0.4 g. of copper turn ings and 13.8 g. of anhydrous potassium carbonate. This mixture was refluxed for five hours. The amyl alcohol was removed by steam distillation. The resulting darkly colored mixture was filtered while hot, removing only a small amount of material. The filtrate was made acid and diluted to about 500 ml. It was cooled with ice, and the precipitate was removed by filtration. The filtrate was dark blue. The precipitate was light green. The precipitate was treated with about 250 ml. of grain alcohol at the boiling point. Some of the precipitate dissolved to give a very dark blue solution; that portion of the precipitate which did not dissolve was believed to be the desired product. The blue filtrate was reduced to about one-half volume on the steam plate. Upon cooling, a dark blue precipitate separated and was filtered off. The light green precipitate was again extracted with about 50 ml. of hot grain alcohol to remove more of the blue color. The filtrate this time was only a very light blue. The precipitate remaining was dissolved in about 40 ml. of 1.0 N sodium hydroxide and reprecipitated with 1:1 HC1. The precipitate was then a light yellowish-green and the aqueous filtrate was only slightly blue. The precipitate was dried overnight in the 110° oven. It was then broken up and ground in a mortar. The melting point was rather unsharp at about 295°C» The references for 2,2* imino dibenzoic acid indicate 295° and. 294-5°C. (28, 29, 30). Titration with standard sodium hydroxide resulted in an answer of 128.4 for the equivalent weight; the calculated value is 128.6. The yield was about 18 g. (IV) Preparation of 2,2*hydrazo dibenzoic acid (32). Twenty-five grams of sodium hydroxide, 2.5 g. of zinc oxide, and 0.2 g. of CdtNO^)^ S K ^ O were dissolved in 75 ml. of water. This solution was mixed with 41.8 g. of o-nitro benzoic acid in a 250 ml. 206 beaker. By means of an oil bath, the temperature was raised to 102°C. The mixture was continually stirred while 15 g. of granulated aluminum metal were added in small portions during three hours. The temperature was maintained between 95 and 110°C. The major portion of the aluminum was added between two and three hours. The mixture became increasingly red as the addition of aluminum proceeded. After the aluminum was all added, the heating was continued at 100 to 110° for about three hours longer. The color gradually changed from red to orange, and some material began to settle to the bottom. The hot mixture was poured into 400 ml. of distilled water. This suspension was filtered, and some brown precipitate was retained. The filtrate was made acid with dilute sulfuric acid. A considerable amount of yellow precipitate appeared. This was filtered with difficulty. It was washed by removal from the paper, mixing with water, and again filter ing. This yellow material was dried at 110°C. for twelve hours. The material was broken up in a mortar. It was treated with about one liter of hot dilute ammonia. All but about one-fourth dissolved to give a red solution; this undissolved material was filtered out. The filtrate was made acid with dilute acetic acid. A yellowish-tan precipitate appeared. This was filtered, washed with water, and dried at 110°C. This material was treated with about 700 ml. of grain alcohol on the steam plate. A small portion did not dissolve and was filtered off. It was very dark. Two portions of charcoal reduced the color of the fil trate from a dark red to a light yellow. The volume of the filtrate was reduced to about 300 ml. Upon cooling in ice water, most of the solute came out as a cream-colored precipitate. This material was filtered, dried at 110°C. for one-half hour, and placed in a vacuum desicator. The filtrate was added to an equ»l volume of distilled water and cooled. A smaller amount of dancer material separated. This was discarded. The product started to darken at 220°C. It turned black, melted, and evolved gas at 227-228°C. The yield was about 9 g. The equivalent weight found by titration was 136.1, the same as the calculated answer. In view of the fact that this compound has been reported to (32, 33, 34), which 207 has exactly the same composition and equivalent weight as the desired product, it seemed desirable to determine whether or not the product above contained any of the rearranged material. For this purpose, a small portion of the product was deliberately rearranged by boiling in 2Cf/o hydrochloric acid. A light green material was obtained. The infrared spectra of both were run. A comparison of these spectra indi cates that the main product does not contain the rearranged material. The rearranged material turned black at about 290°; it did not melt below 310°C. The melting point of 227-8°C. indicated above is 23° higher than that reported previously (73)* (V) Preparation of methylene dianthranilic acid (36). Twenty-five grams of anthranilic acid was mixed with about 55 ml. of grain alcohol. To this was added 6.75 ml. of 3T/° formaldehyde. The mixture immediately started to thicken; after about 25 minutes the consis tency was like a thick milk shake. The alcohol was pushed out of the precipitate by suction filtration. The white cake was broken up into two liters of water. The flocculent precipitate was filtered after first being allowed to settle for about twenty minutes. The material was dried in a vacuum desiccator. It weighed about 23 g. The product was recrystallized from about 200 ml. of acetone; about 7 g. of product finally was obtained. The white crystals start to turn yellow at 150°C., are quite yellow at 160°, and melt to a brown liquid with vigorous evolution of gas at 160 to 162°C. The measured equivalent weight of 144.0 compares with the calculated value of 143.2. (VIl) Preparation of W,TJ' trimethylene dianthranilic acid (37). 1,3-bibromopropane was distilled to purify it. The main portion distilled at 164-165*5°0. One-hundred and fifty ml. of absolute alco hol, 55 g* of anthranilic acid, and 21 g. of 1,3-dibromopropane were refluxed in a 500 ml. flask for eleven and one-half hours. After cooling, the expected (37) yellow precipitate did not appear. The volume of the liquid was reduced to about 60 ml. on the steam plate. Cooling in ice then caused the entire volume to solidify. The alcohol was pressed out on a suction filter; however, the precipitate was still rather pasty. Hence, it was further dried on the steam plate for about 8 hours, with 208 occasional stirring. The precipitate was treated with about 120 ml. ofboiling acetone; only a small part dissolved. The mixture was cooled in ice water and then filtered. The purpose of this extraction was to remove unused reactants, especially anthranilic acid. The precipitate was placed in the 110° oven for one-half hour. The precipitate at this point melted unsharply at about 175 to 180°C., which is 50° too low. It was next dissolved by making 250 ml. of an aqueous suspension basic with 1:1 NaOE, Then the yellow solution was brought down to pH 2.5 using 1:1 HC1. The precipitate immediately reappeared. It was filtered off and washed with 50 ml. of distilled water. After drying for one hour at 110°, the melting point was still found to be about 30° low. Dioxane was tried as a solvent for recrystallization on a small portion; it was not satisfactory. The reason for the low melting point was probably the presence of unreacted anthranilic acid. The UaOH - HCl reprecipitation accomplished little and should be omitted. It was found that anthranilic acid is considerably soluble in cold acetic acid, but that the II,If trirnethylene dianthranilic acid is appreciably soluble only in hot acetic acid. Therefore, the approximately 15 g. of impure product was treated with about 50 ml. of hot acetic acid on a steam plate. It did not quite all dissolve, but more acetic acid was not used to avoid excessive loss. The hot acetic acid suspension was cooled in ice, but not frozen. Some of the precipitate did come out. This was filtered out and washed thoroughly with cold water to remove acetic acid. Water precipitated the anthranilic acid from the acetic acid filtrate. The product was dried overnight in the vacuum desicator and then for one hour at 110°G. It was broken up in a mortar. The weight of o the final product was 4*1 g. It melted at 209 C., which is in exact agreement with the value given by van Alpnen (37). It turns brown and evolves gas upon melting. It was further dried under vacuum before titration to determine the equivalent weight. The answer thus obtained was 157.4 ± 0.2; it should be 157.15. (VIIl) Preparation of H-( aminoethyl)-anthranilic acid. 31.4 G-. of o-chlorobenzoic acid, 25.6 g. of anhydrous potassium 209 carbonate, 32 ml. of ethylene diamine, 68 ml. of n-amyl alcohol, and 0.3 g. of copper turnings were refluxed in a 500 ml. flask for five hours. The amyl alcohol and remaining ethylene diamine were then steam distilled out. The hot aqueous solution was filtered. The filtrate was chilled in ice; then the pH was lowered to about 7.7 using cold 1:1 HC1. Previous work had indicated that this should be the isoelectric point. The product should be most insoluble at this pH; a trial experiment indicated that o-chlorobenzoic acid is appreciably soluble at this pH. A precipitate did appear, and after further cooling, the mixture became quite pasty. It was filtered with suction. This precipitate was very light yellow. Lowering the pH of the filtrate to 0.5 produced more precipitate which should be mainly o-chlorobenzoic acid. The above pH 7.7 precipitate was treated with 160 ml. of boiling absolute alcohol. Only a part dissolved. The mixture was then cooled in ice and filtered. The precipitate was cream-colored, and the filtrate was amber. The purpose of this operation was to remove unused reactants, especially o-chlorobenzoic acid which is appreciably soluble in alcohol. The precipitate was suspended in about 400 ml. of distilled water. The pH was lowered to about 2.5 using 1:1 HC1. Most of the material dissolved to give a yellow solution. About 1 g. of material did not dissolve and was filtered out. This white precipitate should be unre acted o-chlorobenzoic acid which was precipitated or coprecipitated at pH 7.7 and not extracted entirely by the alcohol above. The pH of the yellow filtrate was returned to 7.8 using 1:1 NaOH. The cream-colored precipitate anticipated did not appear; the solution became only slightly cloudy. In order to recover the product from this 500 ml. of yellow colloid it was necessary to pull off most of the water at reduced pressure. Then, after cooling, a large amount of precipitate did appear. It was filtered off and placed in the vacuum desicator. It dried slowly there. The object of the above approach to the isola tion of thi3 product was to isolate it as the amino acid having no hydrogen chloride attached. The molecular weight as determined by titration with NaOH was 203; it should have been 180.2. A recrystallization from hot water lowered it to 190, but after a second recrystallization it went back up 210 to 193. Loss of material was considerable. It was then decided to try for the hydrochloride. The various portions of the product which had failed to give correct molecular weight were treated with the minimum amount of 1:1 HC1 required to dissolve the total. After chilling in ice water, 5.3 g. of crystals were filtered off. These were washed with 100 ml. of ethyl ether and dried overnight in vacuum and for one hour at 110°C. The melting point was sharp at 245-6°C. with evolution of gas. Titration with NaOH indicated that two hydrogen chlorides per molecule are present. This was quite unanticipated as one of the amine groups is similar to that of anthranilic acid, which presumably would be rather difficult to obtain as the hydrochloride. The calculated molecular weight for the dihydrochloride of N-(aminoethyl)-anthranilic acid is 253.2; that found by titration was 253-5 ± 2.0. The percent of chloride is 28.05; that found by titration with standard silver nitrate was 28.08. It seems probable that the procedure could be shortened and the yield much improved if the material remaining after the alcohol extrac tion were treated directly with hot 1:1 HC1, in which the desired product is very soluble; that small amount of o-chlorobenzoic acid still present being filtered out while the solution is still hot. Then, upon chilling, the desired dihydrochloride would crystallize out as above. (IX) Preparation of 2-(aminomethyl)-benzoic acid. Step A. Phthalic anhydride was converted to phthalimide. The directions found in "Organic Synthesis," Vol. I, page 457, were followed on a one-quarter scale using a one liter flask. The yield was 100 g. Step B. Phthalimide was converted to phthalide. The directions found in "Organic Synthesis," 16. 71, (l936), were followed on a two- thirds scale using the 100 g. of phthalimide obtained above. The period of addition of the phthalimide was 3/^ rather than l/2 hours; the evolution of ammonia required five hours rather than three. The yield was 67 g. Step C. Phthalide was converted to o-carboxyl phenylacetonitrile. The directions found in "Organic Synthesis," 22. 30 (1942) were followed on a two—thirds scale using the 67 g. of phthalide obtained above. 211 The yield was 33.2 g. of material which melted at 106-8°C. Step D. 0-Carboxyl nhenylacetonitrile was converted to homophthalic acid amide. Essentially the directions given in "Organic Synthesis," Vol. II, page 45, were followed. Because the compound involved is not the same as that described in "Organic Synthesis" (in the above three steps it was), the procedure will be described in detail. One thousand and thirty g. of 3'/3 hydrogen peroxide, 120 ml. of 25^ potassium hydroxide, and 33.2 g. of o-carboxyl phenylacetonitrile were placed in a three-liter flask. A heating mantle was used to raise the temperature to 43°C. Mechanical stirring was provided. The mantle was removed; the temperature rose to about 51° and remained there for about one-half hour. Vigorous evolution of gas occured during this time, but slowed as the temperature slowly declined. The solution was yellow during this time. Frothing did not occur. After about one hour, the temperature had dropped to 45°. The flask was cooled to 35° under a tap. The solution was made acid with 1:1 HC1; a white precipitate appeared. The suspension was cooled in ice water for one hour. The white precipitate was filtered off and placed in a vacuum desiccator overnight. The yield was 25.3 g. Step E. Homophthalic acid amide was converted to 2-(aminomethyl)- benzoic acid by a Hoffman degradation. The procedure used is similar to that in "Organic Synthesis," 16. 4(l936) . Chlorine was produced in a 250 ml. distilling flask by letting 65 ml. of concentrated hydrochloric acid slowly run in to 10 g. of potassium permanganate. The chlorine was bubbled into a mixture of 150 g. of ice and a cold solution of 40 g. of sodium hydroxide in 250 ml. of water. This took about one-half hour, the distilling flask being boiled about five minutes at the end. Then the 25.3 g. of amide obtained in step D above was added to the alkaline hypo chlorite. The temperature was slowly raised to 70°. After about one hour at 70°, a solution of 60 g. of sodium hydroxide in 60 ml. of water was added. Then the temperature was raised to 85° for one hour. The yellow solution was chilled in ice water. It was neutralized with 1:1 HC1 during this cooling. A considerable amount of gas was given off. A tan precipitate appeared; this was filtered off. The volume of the filtrate was about one liter; it was pale yellow and tended to foam. 212 The tan precipitate was vacuum dried. It weighed about 1 g. and melted very slowly between 165 and 174°C. The filtrate was reduced in volume by bubbling air through it at reduced pressure. This took about 12 hours. At about 400 m l ., a cream precipitate appeared. At about 300 ml. total volume, the precipitate was filtered off, after the suspension had been chilled in ice water. A second portion of precipitate was removed at about 100 ml. These two precipitates were combined and treated with five successive 100 ml. portions of boiling methanol. Apparently some solution did occur. The precipitate became pure white, and is believed to have been sodium chloride. The combined metmnol filtrates were yellow, and were taken almost to dryness on the steam plate. The final traces of the filtrate liquid were removed by a one-half hour drying in a vacuum desiccator. The resulting material was ground in a mortar. It weighed 15.3 g. It melted at 220 to 223°C., preceded by a lively breaking up of the larger crystals and some softening at 190 to 200°. This material was recrystal lized three times from hot water, with considerable loss each time. The equivalent weight as found by titration with standard sodium hydroxide would not drop to the correct value of 93.85. A better method of recrystallization was found. The hydrochloride of the amino acid was dissolved in the least possible volume of boiling water. This solution was cooled in ice water. Then an equal volume of concentrated HC1 was added; this caused precipitation. After further cooling, the suspension was filtered. This method was used twice. The product was then dried in the vacuum desiccator overnight and in the 110° oven for one hour. The final yield was 7.5 g.; it would have been considerably better if HC1 had been used in each recrystnllization. The equivalent weight of the final product was 94.25. It is light cream in color aid melts sharply, turning light green and evolving gas, at 217-8°C. (Xl) Preparation of o-(carboxymethoxy)-benzoic acid. Twenty-seven and six tenths g. (0.2 moles) of salicylic acia and 18.9 £'• (0.2 moles) of chloroacetic acid were dissolved in 74 ml. of sodium hydroxhde solution which contained 24.0 g. (0,6 moles) of NaOH. This solution was maintained at $0-93°C. on a steam plate during about three hours. The sodium salt of the product soon started to separate. 213 The suspension was cooled; then enough water was added to dissolve all of the sodium salt. From this solution the product, and also unchanged salicylic acid, was precipitated by adding cold 1:1 hydro chloric acid. After chilling in ice water, the suspension was filtered, washed with cold water, and vacuum dried. The separation depended upon the ready solubility of salicylic acid in ether (5 0 g. per 100 ml. at 15°C.) ('75). The desired product is quite insoluble. Seventh-five ml. of ethyl ether was used in one portion. The product was filtered out and dried in vacuum. The yield at this point was 18.0 g. After three recrystallizations from boiling water and vacuum drying, 12.4 g. of beautiful large white crystals were obtained. These melted at 191-192.5°C. Meyer and Duczmal (4 0) give 190-192°. Synerholm and Zimmerman (76) indicate 187-8° (uncorr.). The equivalent weight obtained by titration with standard sodium hydroxide was 98.1 jr 0.3; the calculated value is 98.1. (XIl) Preparation of N-(carboxymethyl)-anthranilic acid. Haller (4 2 ) has published a complete study of the yields of this compound obtained by variation of the conditions and the reagents used. His recommendation of the use of sodium carbonate rather then sodium hydroxide is probably a very good one. In this connection, it should be noted that Philips (4 1) recommends a procedure using neither sodium carbo nate nor sodium hydroxide as yielding a purer product. 27.4 g. (0.2 moles) Of anthranilic acid and 18 g. (0.185 moles) of chloroacetic acid were placed in 200 ml. of distilled water. This solution was kept near boiling on a hot plate. 24 g. (0.6 moles) Of sodium hydroxide was added to neutralize the two acids. Then the pH was maintained slightly basic for one-half hour, during which time 16 g. more of solid sodium hydroxide were added to m e t with the hydrochloric acid formed. The solution was heated an additional hour. After cooling in ice water, it was slowly neutralised with cold 1:1 hydrocliloric acid. At one point the suspension was quite thick. This was probably the mono sodium salt; therefore the addition of HC1 was continued until the pH dropped below 2. After thorough chilling, the precipitate was filtered out and vacuum dried. It weighed 24 g. and melted at 143°C., as does 214 anthranilic acid. This material was recrystallized twice from 1:1 acetic acid. The yield was then 15.0 g. of very light yellow material which melted at 214-215.5°C. This 15 g. was combined with 5.9 g. of similar material obtained from a preparation of anthranilic acid diacetic acid being carried out at the same time. This combined material was twice recrystallized from 1:1 acetic acid to give about 14 g. of product melting at 215-6°C. host of Haller's (4?) products melted at 205-7°. Etienne (43) gives 218°. Guha - bircar and Datta (44) give 209°. Vorlander and liumme (45) state that the melting point is about 215°, but that an exact value is not possible because the acid starts to decompose before it melts. These authors also state that the product should not be recrystallized from boiling water or dilute mineral acids because the aromatic carboxyl group comes off, yielding aniline acetic acid. They recommend that methanol be used to recrystallize N-(carboxymethyl)-anthranilic acid. The equivalent weight obtained by titration of the product with standard sodium hydroxide was 97.6 + 0.2; the calculated value is 97.6. (XIII) Preparation of anthranilic acid diacetic acid. Thirteen and .seven teen the g. of anthranilic acid and 23.0 g. of chloroacotic acid wore added to ISO ml. of uistilled water. This was made slightly basic, and maintained basic by the gradual addition of solid potassium hydroxide during two and one-half hours of heating just below boiling. After about one and one-half hours from the start, about 8 to 10 g. additional chloroacetic acid were added, and of course, sufficient potassium hydroxide to keep the solution basic. At the end of two and one-half hours, the solution was cooled. Then it was made acid to below pH 2 with cold 1:1 hydrochloric acid. After further chilling in ice, the precipitate was removed by suction filtration. This precipitate was recrystallized three times from boiling 1:1 acetic acid. Then it was vacuum dried. The yield was 15.4 g. of white material melting at 208-209.5°C. The equivalent weight was found to be 85.5 which is more than 1'fo higher than the correct answer of 84.4. This material was three times recrystallized from hot water, which procedure raised the melting point to 210-212° but did not much improve the equivalent weight. This material was dissolved in 215 about 300 ml. of boiling water. Removal from the hot plate and sitting several minutes without chilling brought out about two-thirds of the material as a white precipitate. This was quickly filtered out of the hot suspension. This precipitate should contain most of the less soluble impurities such as anthranilic acid and N-(carboxymethyl)-anthranilic acid. The filtrate was chilled in ice water for more than an hour. Most of the remaining material did crystallize out. It was then removed by filtration. After vacuum drying, this second precipitate had a melting point of 210-212°C., and an equivalent weight of 84*4 ± 0.2. 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I, William Allen Young, was b o m in St. Marys, Ohio, May 21, 1930. I received my secondary school education in the public schools there. My undergraduate training was obtained at Miami University, from which I received the degree. Bachelor of Arts in June, 1952. I entered Ohio State University in October, 1952, and received the degree Master of Science in June, 1954. In October, 1952, I received an appointment as University Scholar at Ohio State University, where I specialized in the Department of Chemistry. During the school years 1954-55 and 1955-56 I held the position of Kettering Research Fellow while completing the requirements for the degree Doctor of Philosophy.

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