THE UNIVERSITY OF MINNESOTA

GRADUATE SCHOOL.

Report of Committee on Thesis

The undersigned, acting as a Committee of the Graduate School, have read the accompanying thesis submitted by Glenn Earl ·atthe s

for the degree of Laster of Science. They approve it as a thesis meeting he require- ments of the Graduate School of :he University of Minnesota , and recommend that it be accepted in partial fulfillment of the requirements for the degree of Mester of Science.

--~-~--Chairman . riJt;/J /t...P -' A.Jt .Jt ..... -7. .._f!!::. ... ~ ....; K-·······-········ ·······-·ff ····-••••••• L ,q,, ·-··· --~,.. _.f., .. 'l~-- --·· ... p~,,...... :?_f_ ...... l*ft o··-·-··-·· THE UNIVERSITY ·OF MINNESOTA

GRADUATE SCHOOL I I I I tl I Ill It 1 11 I ttl I I ,•, :'.' 1 1 I Ill : : :·· : : 1 : :I :I: I I I : : 1: . ..I c,t II II: '•:: ... :II: .. I I I : : :

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I 1111 ttl I ttl I I of : : : .•· ! •• : •. : •• ·.: 1 1 t I I 1 It I I I I Ill I 11 1 I I I I I I I Committee on Examination

This is to certify that we the undersigned, as a committee of the Graduate

School, have given Glenn Earl atthews final oral examination for the degree of Master of Science. We recommend that the degree of Master of Science be conferred upon the candidate.

apolis, Minnesota

_... :? .. ~ .... -.. 1 9l!t./ ..- 1. -· ....·...... ·-···-·············-·-· .. Chairman ···········-~-~- ---··············· ~ ··-j-·L _____t_'L~ A Comparison of the Absorption Spectra of Diphenylamine and Carbazole and Several of their Derivatives

A Thesi s Submitted to the Faculty of the Graduate School of the University of viinnesota by Glenn Earl I{atthews I

In Partial Fulfillment of the Requirements for the degree of Master of Science in Chemistry May

192 1 • ,, A Comparison of the Absorption Spectra of Diphenylamine and Carbazole and Several of their Derivatives .

I . General Discussion of the Theor:es of Color. Introductory. Color had been a subject of general interest to people for

~any centuries before the beginnings of scientific investigation. This interest was centered around the application of natural dyes, like madder, purpurin, and indigo. The first artificial dyestuff was synthetically made by A. ". von Hoffman and Sir Wm . Perkin and ap- peared under the name of "mauve" in 1856. In the years that fol- Jowed, the dye industry grew rapidly and by the time the synthesis of indigo was accomplished by A. von Baeyer in 1880, chenists had proven undeniably that any color could be reproduced if the investi­ gators were willing to give the time and study necessary for its preparation. As the basis of structural organic chemistry, depend- ent on the Principles of Kekule published in 1868, was being formed at the same time, it was quite natural that an interest should be aroused in the cause of color. To facilitate an understanding of the discussion that follows, it is pointed aut that the terms, "col­

ored" and "colorless" as applied to the compounds ~entioned are to be taken in the sense of visible color. We find Graebe and Lieber- ;~ (\, mann recording the first observation on the subject.1 They con-

~ eluded that the phenomenon of color in organic compounds must

.. 1 - Ber. 1867, 1 , 104 . \1) i 290~?8 ~======~ - 2- be associated in some way with unsaturat· on . as reduction as well as addition of halogens seemed to cause all known colored compounds to become colorless. The Chromophore Theory of O. N.Witt .

Several years later, in 1876, the theory of O. N. Witt ap­ eared. 1 According to this inv es ti ~ ator, co I or was due to the presence of certain groups, unsaturated in character, which he teroed chromophores . Those most frequently appearing are M=N'

N=O, N02, c•O, C:S, C~ , and C=c . The molecule that these groups were held by was called a chromogen . It can be seen that as time passed and more colored substances were discoverd, new chromophores had to be added to the list . This looseness of application of the theory is somewhat fortunate in that it is only necessary to pick out a new chromophore to explain the color of a part_cular substance It does not, however, aid us materially in arriving at a definite explanation for a cause of color that will hold without addit ons or subtractions for all subst ~n ces . The theory has been a basis for an extended investigation of the cause of color and has served to stimulate the development of many additional theories . As chromogens may or may not be col- ored, it was next postulated that the addition of certain salt- form­ ing groups to a colorless chromoeen would render it colored. These groups were called auxochromes. Their addition to a chromogen caused the chromogen to become a dyestuff. Examples of auxochromes

There is an exception to this rule, as for

1 • Ber. 187 6 . 9 , 522 . -3-

instance, the sulphonic and carboxyl groups do not possess the abil~ ity to produce color in a chromogen when tied to it. Oftentimes a sinele chromophore will cause visible color to appear, but it is more often the result of a piling up or "mass effect" of several of these groups which appears to be the direct cause of color. Examples of the effect of the addition of chromophores on the color of compounds appear in the following types, wherein it is to be not­ ceu that the formulae on the right hand side possess several chrom­ ophores whereas those on the left have only one. c, f/5' - c, f/5" C,tlr;- CH = CH- Cf/= Cll- c, Hs-­ Diphenyl - Colorless Diphenyl hexatriene - Yellow. cl Hs, 'C, H:,- c, Hlf ~c., · I/~~- "c= c/ / ~c=c"-.) c~. J/lJ. c, 11~~- C,H~. / " C,H~ Tetraphenyl ethylene - Colorless Bisdiphenylene ethylene Red.

Benzophone - Colorless Benzil - Yellow. =c. The group 'c= which appears in the fulvenes discovered by =e/ Thiele1 s eems to possess color carrying power. Examination of t he color of many hundreds of coopounds have yielded the conclusionE relative to the effect of the addition of these groups as described in the next paragraph. The c;o group does not lend color to the simpler aldehydes and ketones, but it appears , as shown above, to give this power to the more complex series. · Both the N:N and the C=S groups are t-strong chromophores as nearly all substances in h ch they are found, are colored. Many nitroso compounds are c aracterized

1 Ber. 1900, 33, 666 ~ 85 1, 3895. ) -4- a blue or green color effect, whereas tr1e nitro group gives yellow t

some compounds, but leaves others s~ as the nitro-paraffins color- less. Furthermore, additions of two or more groups instead of increasing the color, sometimes dinininh it. Such an effect is shown in nitro benzene which is yellow, while the di- and tri-nitro benzenes are colorless . As a result of the ability of certain chromophores, like N; N and C=S being able to produce color, while others like C=O and C-G do so only 'l"lhen aided by the proximity of other groupa, Kauffmann separated the chromophores into two classes, the independent and the dependent chromophores . This varied nature of the chromophore group and the general looseness of the theory is probably what stimulated Armstrong and Nietz~i to search for a fund- mental chroopphore.

The Quinonoid Theory.

Both H. E. Armstrong and 1ietski published,in 1888, a theor that s now knovm as the "Quinonoid" theory. 1 It was an attempt to show that the essential cl1rooophore for the production of color was of the type found in quinone, two varieties of which appear below. =0= Pqra Orfho In his second paper, 2 Armstrong states, "although the general correc ,.. !ness of this view has never yet been aclmo ledged, a study of the literature relating to colored compounds clearly shows that it is

~ore and more recommending itself; it should also be ment oned that Hetzki, in the introduction to his Orgru1 sc_ e arb toffe, makes ref

1 -Armstrong . Proc . Chem . Soc . 1888 27. Nietzki . "Organische Farbstoffe r, 1888 Sprine;er, Berl 1 2 .- Armstrong Proc Chern Soc 18Q2 101 -5- erence to the quinonoid character of a number of dyestuffs, although he does not seek to apply such a view of their structure generally.

~he subject has contim..&4Hy occupied my attention since I first

bro~1t it before t he Society, and I think it justifiable that I should now state the opinion at which I have arr·ved, viz. , tha.t in the case of colored comp ounds , v1hi ch have been f airly vrell studied, it is so generally true t hat a qulnonoid f ornula is applicable, that the reconsideration of the f ornula of any colored substance is vrar-

~antable if it is not to come within this rule. The term 11 quino- poid",must however, be understood to include compounds of the type o:f in ~enzil ; and it is to be noted thaththe case of closed chain compound~ it appears to be essential that at least one of the quinonoid carbon atoms be associated with a dyad radical, and that the ring it self be unsaturated. The presence of t o ortho or one para carbony group in a saturated ring apparently does not condition colour. " In the remainder of the paper, he endeavers to explain the apparent anomaly of the yellow color of the ortho nitro phenol a.nd the colorless para derivative. He showed that the methoxy nitro benzenes prepared from both, are colorless . For several reasons,

!Which he further states, it seens ju t:Lf .l ble to say that these two compounds are not mere position isomers and that the forr.1ula for o­

~itro phenol may be written quinoid by transferring the hydrosen ,fJ oy\ from the OH group to the N02 group as shown. This case hc.s been inserted to shov1 an example o =N=o of a type of change which is resorted to many

~imes in the literature to explain the color of a compound . As Coher states in his "Organic Chemistry", this t heory has "one important

1 -Cohen. "Organic Chemistry. " Vol . II. p . 95. - 6- attribute which most other theories lack; it lends itself readily to experimental proof or disproof and is accountable for a valuable ex­ tension to our lmowledge of dyestuffs . " There are, however, quite a number of apparent exceptions to this thecry ; i . e ., several colorless compounds which are most cer ~ainly quinoid and several colored substances which cannot be shiftec ~o show a quinoid structure. Examples of the former are HN = G. H4 = N H o = c, H4 = N H Quinone diimine - Colorless Quinoneimine - Colorless

~hile several examples of the latter appear in c(. and ~ ni tronaphthalene

~itrodi methyl quin ol , the two benzal nitroanilines, that are yellow

~d orange , and the quinhydrones . It can be seen that this theory ~oes not fully satisfy the conditions which a rigid color theory must

Kauffman ' s A~~ ochrome Rule .

Kauffmann formulated a rule and published his results in 904 . 1 It may be thought of as a branch of itt's Theory in that hi conclusions state that t he auxochromes tend to deepen the color hen

~ttached indirectly to the chromophore by an aromatic nucleus, which can act as a chromophore. The term "depth of color" has a different meaning than usually considered. To t he color chemiat, the conple­

ments of the ord(ary spectrum arrangenent a~e used and in order of epth, t he colors run, - green (deepest), blue, violet, r ed, orange, and yellow. Kauffmann made·a very extended study of the behavior of substances under the influence of Tesla radiation (high frequency current d schcrge) .t He concluded from a comparat ve study of

luminescent compounds that they a.re in the ma n, benzene der_vatives

1 - Kauff.nann . "Farbe und Constitutmon. " Ahrens ' VortrHge . 1904, 9 , 277 2 .- Ber. 1900 , 33 , 1725; 1901 , 34 , 682 ; 1902 , 35, 3668 -7-

containing certain groups , which he called luminopho~es . Benzene i regarded as the seat of the luminescence, and though only feebly luminescent itself, it becomes more so on the introduction of auxo- c1romes , by increasing the number of aromatic nuclei( naphthalene and anthracene) , end by the linking of nuclei with unsaturated car­

bon ator:1s . .Many other properties ap~J- ear to run parallel with lUJn j_ne s c8nce • s for example the tendency to oxidize to quinoid com- pounds which is proportional to the strength of the luminescence . Kauffman therefore came to the conclusion that the benzene nucleus differed in different compounds . Those compounds possess ing strong luminescence may be thought to possess the Dewar forrmla

I, the non-luminous substances 1 the Claus diagonal ring III, and the interoediate stage characterized by moderate luoinescence, the form ula of Kekule II. 0 I. II. III. An example would be of interest to show how he applied his idea. laphthalene, which shows fairly strong lumine ~ nee under Tesla rays is concluded to possess one ring like I and the other as in II .

Ben.z:ene

itro benzene has almost no luminoscity, so it would have the Claus foroula. In general, the following condition represented belo was concluded to be true. Addition of negative groups Auxochromes added -t-o I -1-o .zu:: NO N=N COOH C=O ----~ r r. obj ct one r 1 0 h ory r n n:

Al y on o 0 0 oc ro c ct

Hydroxy gro n t 0 c o no ro c co or, r t ey 0 ccor n or .

z ch' h or 0 c ro o 0 r1

Contrnr to 0 d tz c r

d erent explan on 0 c u 0 color.

orking on th 0 co

colore an colorl s or of c

c lled t e _t _ n1 ro h r 0 h r . for ul

c 0 lo co or uc to r c 11 r

are t ere or co .I.. co col- rt 0 ch

b 0

t eor o "lane · o e s d e o ec 0 on

- 3er. 6, 39 - 9- 1m to propose that the nitro group could exist in three different

orms : (1) a true nitro group ; (2) a simple aci- nitro group )C GNooH ; /x 3) an aci-ni tro group repres ented by R - C Noo H where X= strong egative radicle (N02 , NOH etc., ) . It vms further found that be- ides different metals and organic bases producing differently color­ d salts, the same metal sometimes yields differently colored salts nd solutions according to the solvent used. Potassium, rubidium, o

aesit~ diphenyl violurate can each be prepared in blue and red mod- fications . This phenomenon he called pantochromoism. t An added ifficulty arose when it was found that different structural modifica ions m y possess the same color and identical absorption bands in olution. He defined this effect a.s honochromisomerism. 2 There re so great a variety of colored substances that it hardly seems ecessary to resort to isomerism as an explanation of all the possibl hanges. Many of them, no doubt , could be explained by polymorph-. .s:n, while other cases may be due to the fornation of a solvate or the union of solvent anQ solute .

Beteyer' s Theory.

The triphenylmethane series of dyes offer an interestin fie1d to the color chemist and ith the discovery of triphenyl methyl by Gomberg in 1900, interest has been centered cons derabl more on this series . For insta..1c:e, the sulphate of p-t:r chlortriphenyl carbinol may be represented by such a formula as I, as it is stron0 - ly colored. It is found, hOi7ever, that the chlorine atoms possess equal stability. Introduction of methoxy groupE- nto the nucleus enables isolation of mD~e stable co]o ced salts . Trianisyl nitrate - Ber. 1909, 42, 966; 1910, 4 3, 45, 68,82. 2 - Ber. 19 10 , 4 3 , 19 10; 19 11 , 44, 200 1 • -1 0 -

It should possess a structure like II, a ccording to the quinoid hypothesis . /CHJ (c ~ o c, H"')z. c = 0 =a" ox II. It is found, however, that t he methyl group is not easily detached

in compe.rison with the metal radicle <1nd t::1e trianisyl compound sho

react differently fro the isomers with t :1e OCH3 croups in t~e and meta positions . Baeyer bel· eved this difference between t::1e colorless and colored salts and the i nnisation of the latter to be due to an oscillation of t he quinonoi d condition between two or benzene nuclei . 1 He takes the stand that the quinoid structure does not explain color in this series . It is explained, preferab by the character of t!:le oscillations, which are in turn dependent o the structure. of the molecule . Ac cording to Cohen2 , " the benzene nuclei must be represented as alternately possessing the structure of Graebe ' s superoxide formula, whilst the fourth carbon valency ex­ ecutes, as it were, a pendulum motion between t }le oxygen or ni trouen atoms . The effect may be represented by the followine; formulae .:.

'Cd/1 Schlenk has shown that there are cases where , even in the triphenyl methane series, such osc llations are impos&ible . He cite as an individwal case, p- tetra methyl di aminofuchsone. /QN(cH,J~. (CI-~)/~ 0 -c ~ ~o = o I t appears that t his theor y , which makes use of a conception of os- 1.- Jour. Chem . Soc . Abs . 1 ~07 , i , 504. 2 .- Cohen. "Organic Che~istry . Vol . II. p .119 . - 1 1- cillatory motion wit hin the molecule is not of sufficient gener al ap lication to justify its complete a cceptance.

The Theory of WillstRtter.

WillstHtter made a careful study of the quinhydrones , tin ­ cludins t~e colored compounds prepared by Wurster in 1897, and co~ ­ cluded that the color of these substru1ces is best accom1ted for by assuming the saturation of the partial valencies of the oxygen atoms of the quinone and quinol, as would appear below : ~ ------91-1 "r------o

0,, 0J 0I 0 o- __ _ -- - -o r1 Of/------0 e found the red compound, which Nietzki had called a quinonimine, t e a semi- quinonimine (meriquinonoid), while the full quinon m ne, which he obtained by oxidizine amino dimethylaniline, as colorless. From further investigation, he decided that the olored for1:1 belonged to the quinhydrone series . He explained the ifference between ordinary quinhydrone and urster' s compound h ch xists only in a red modification, by oscillatory motion of the resi al affinities , as shovm above. 2 He postulated furt er that the ame thing may occur in parts of the nolecule, as between a qu no_d q, d.fl aromatic nucleus . This conception was advanced a~ an explana- the similarity of Wurster' s Red and fuchsine.

Several series of compounds have been found, since t~e ap­ of h s first paper, whose color changes seem best explained

theory. 3 1 - WillstHtter and Piccard. Ber. 1908, 4 1, 1465. 2 - WillstHtter and Piccard. Ber. 1908, 41 , 1458 3245. 3 - K . H . J~ ey er . Ber. 1909, 42, 1 149 ; 1910, 43 , 157 ; Werner. 1909, 42, 4324 . Hoff ann and Kirmreuther. Ber. 19 10 4 4 -1 2- F. Kehrmann , in a series of papers, criticis ed strongly the vievrs of these investigators. 1 In one of his papers, publish- ed in 1913, 2 he states that the triphenyl methane bases and 1urster' salts all have the auxochro~e outside the quinonoid portion of the molecule, so that both may , in a wide s ense, be regarded as of the meri-quinonoid type.

Schlenk has also found a pointed objection3, for he pointe out several colored compounds whose structure presents no possibilit of oscillation. An example may be given in the blue conpound of chloranil and quinol methyl ether. o , -"--'------. o t J-/3 :():If 01 I 6 OC.HJ Even though these objections possess a validity which can- not be disregarded, it should be noticed in passinu, the apparently loose molecular conbinations which often produce color.

Baly's Color Theory.

In the theories of both Baeyer and illst[tter, t ' ere is the development of a kinetic conception of the cause o_ color, de pendent on an inner molecular oscillation. Baly and his collabora- tors have published a theory4 which follows somewhat along the same trend of thought . Their idea is essent_ally that of a force field surrounding the molecule. The opening or clos_ng of this field is dependent on the solvent action or the energy of the light aves to

1 -F. Kehrmann . Ber. 1908, 41, 2340; 3396; 1913, 46, 3036. 1915, 48, 1938; 19 17, 50, 856 . 2 - F. Kehrmann . Ber. 1913, 46, 3036 . 3 - Schlenlc. Ann . 1909 , 368, 271 . 4 ~ Stewart and Baly. T. 1906, 429; 502 ; Baly and Try horn. T. 19 1 10 8 . -13- which they respond and which they absorb. fhis opening and closirg of force fields corresponds in a general way vrith the inner-molecula

oscillation conception of Baeyer and ~illst~tter so that further dis

cussion of this theory is not deemed necessary at this poi~t .

The Color Theory of Stieglitz.

At a recent lecture given before the innesota section of the American Chemical Society, Dr . Julius Stieglitz presented his electronic conception of color. He showed that the explanation of Stewart and Baly on the cause of the keto-enol change of aceto­ acetic ester, which is based primarily on an oscillatory oot_on of the hydrogen atom between the oxygen and carbon atoms, is far too slow in action to fit in vri th our oodern idea of color. It was fom1d that it taces three weeks for one gram mole to change froo one form into the other. Rather he would choose to explain all col or changes on the basis of the desire of elements to gain or lose e- lectrons. In other words, whenever a carbon compound is oxydized, one or more of the carbon atoms lose electrons . He explains t e deep color of quinhydrones, which he chooses to repeesent by the formula of Villstgtter, apnearing on paGe 11, as due to o electron trying to escape from the para carbon on the right hand ring. hese electrons oscillate very rapidly with the result that the quinhydron s are more deeply colored than quinone. Sim_larly in t e series of inor~ar1ic salts, AgCl, AgBr, and ~ I, the color ran~es from color­ less in the first salt, to yellow in the second, and deep yellow in· the last. It is explained by the fact that Iodine tends to give up electrons most readily. In an explanation of the color of dyes, he gave two exam- -14 - ples , which were nethyl vi6let and methylene blue, the structural formulae of which appear below : ~ ~) H CcHJ)/}~)-y,----(I)'"(o~;, oi-0-<:-G N ~~tJ~.

c I L R'r I. Deep Violet. II . Colorless.

I ethylene Blue. In I, the electrons are on the two reducinG vroups A and B d t he result is the production of color. If maximum color is de

in -tt\t dye , an alkali is added. In the case of methylene blue has gained electrons , thereby becoming reduced wh le A has lost lectrons and becooe exydized. As no papers have appeared yet, no

efera~c es ~an be given. The theory presents a very intere t · an remising application of our uodern theory of elect!'on exd ange . f\

Suillr:lary.

In an effort to arrive at a reasonable cause for the color eveloped in compounds orsanic in character, itt has given us a

heory which has been the basis of of clearer understand_n o~ t:e

nportant phenomenon and at the sa~e time has stimul ted the forw t o f later theories. Essentially he ex lained the colQr O- organ- c substanceR a due to the presence of certain groups called chroo-

phores r~ttr.chec to a sroup:_ng terrJed chromogen. r .ther, he show

d that addition of various s lt -for~ing groups called auxoc1ro~es -1 5-

o CJ colorless chronocen woulc render it colored c,nd chane:e it to a yestuff . Armstrong then atter.1pted to limit the idee of a chro phore, by showing that there wa.s only one essentic>l chromophore, th found in compounds of the char acter of quinone and that compounds vhich v;-er-e coloreG. and di not pesseos this crouping could be rearrc:.

ed so'that the sroupine; would appear. A slio1t variation of his

ir:itinc; ca.r~ e was present ee by r:auffr.w.nn . He proposed that the enzene nucleus , several f ormulae for v;hich have been e ven, r;a.s c if erent in many substances anC. could be explained by the 1 .inescent which compounds offered to hieh frequency rar' ·_ tion.

Differine; in a large dec;ree from t e for~ oinz:; , but still ad /'i to the b sic idea of -itt, Ha.ntzsch concluded that the color f ore;a.nic subst<:.•.nces r;as best explained by the assumption of t 1e

xistence of isomeric forns one type of r;h ell were never colore .. n alTI"ays colored. He called his idea, chroooisomer o . en evelopine; the conception further, so oru1y compl_c tion arose t at

v ~oun' it necessary to add neu acendments en def ne ne e feet

til e became sone;hat entancled in the oass o h s o~n t h eory.

Shortly a.fter the publicat ·on of Hantzsch' s theor , t o ne-1 t 1eot1es

be see on an c ea of oscH.l4.tory oot~on :ere pubL.shed. l. le"'e .. ere Pr e:par·ed b;r Be.eycr and ;;illstlitter. They are pract aallJ a.l {e in

hat they postulate a-11 inner molecular str"' n lie. cues..., v ra­ tion of the res dual aff niti es of the car on tons t1 t recult n

the product_· on o.ft co 1 or. T1e theor of 3alr, althouv. coucled n

d "":er.ant ern no 1 ors , b r i ne;s ou t'ne mec 11ru1 1 sn o f force f~e~cl surroundine; the molecule, vrh ch is e"'sen i, lly of t 1e c ...1 racte ' of the t wo preced ng theories . Stie litz ' s dea , houever, "ttacks the Question from the electronic st<:>ndpoint ~ nc". dev _ op ... t. e oint Of the loss and gain of electrons . In the end -1 6- he virtually considers tl1e quinono_d tructure essent al to the pro­ duction of color in aromatic compounds . It will be seen from the review given of these theories that a.ll are outgrowths of the fundanental chrooophore theory of Witt . In a general sense, it r.my now be stated that an at on or group of atoos, which joined to a compound give it t he property of visible color may be termed a chromophore. Relative to the depth of color produced by the addition of groups , it appears that no def- inite rule cru1 be applied. It can only be mentioned that some groups such as N=N, N= o, and C• S apparently are more effic~ent and dependable in this respect than other groups as C=O or CH; C_f , The theories have been of great value in directin£ and correlat ng the work of the color chemist .

Diphenylamine and Carbazole.

The two compounds , diphenylamine and carbazole, are now f ncine; extensive use a.s important internedi t for the preparation o" certa n dyes . Due to t .s cp l c tion, it ·auld be of cons d erable interest to study the effect of auxochrone addit:on on the color of these compounds . he compounds are u ually rep esented Y the structures given below ·/)~ ·II· u~/y'~ ~I ~ Diphenylamine . Carbazole. oth compounds are colorless in the free state. The deri at: es investigation were the N=O, the ro2 and the indophenols . of comparison was t he selective absorption evidenced by hese substances i n the ul tra- v .Olet part of the spectrun as far as could be examined b -1 7-

II . Absorption Spectra.

a . Theory of Absorption Spectra. With reference to the spectrum, generally speaking, there are two kincls of absorption. The first is eenera.l absorption, which consists in a general weakening of the whole spectrum. The eecond s selective a.bsorption wherein parts of the spectrum dis- appea,.... clue to 2.bsorpt ... on . These parts may be only lines or again as is the case in most aromatic organic substances, they may be a series of lines , which would be called a band. Visible color is produced by selective absorpti on in the visible spectrum rhereby pari of the white light passing through a solution of a substance is Plucked out . If a solution appears green, for exaLlple , it would in· dicate that all the spectrum except the green had been absorbed • .. After a careful study of the vi ible spectrum, Prof . Stokef of Cambridge reached the conclusion that the electric spark, no mat­ ter whether it was produced by a pri e conductor of an ordinary electrifying machine, or by the discharge from a Leyden jar, gave of1 rays of very high refrangibility, surp ssing any of the solar rays .,

~rthermore , he discovered that these rays pass freely through quartl

~hile glass absorbs them. He therefore procured a len and priam oj RUartz and on exa ining the solar spectrum, he discovered that an in·

~isible region existed which extended as far beyond the previously

~own part as the l att er extended beyond the visible . In the same

~ear , Prof . · iller of Ki ng ' s College, London, publlshed a paper de­

~cribing the method by which he used a photographic plate to record

1 - Phil. Tr ans., 1 52, 463 . -18- .his invisible or ultra-violet snectrum.1 On further study of the subject, it as discovered that early all colorless aromatic organic substances possess absorption bands in the ultra-violet part of the spectrum, whereas addition of certain groups appears to produce an accompanying shift of the band or bands over into the visible. Therefor e as Watson states, " a study of the color of a substance thus involvea the examination of its entire visible and ultra-violet spectrum, and further, as Hartle and his successors have shown, of the chanee of the absorption with ,, the concentration of the absorbin substance. 2 It shoul also be mentioned that bhere is an infra- red region of the spectrum, charact erized by its heating effect and possessing rays of long ave length bsorntion in this region is measured by the heating of an electr ca resistance in an instrument known as Lan ley's bolometer. Coblentz conducted a very comprehensive investigat on of the infra-red re ion

and has published his results in several voluoes . 3 After several years of investigation, it as concluded tha an important use of absorption spectra was the determination of the formula of a substance whose structu as doubtful, by comparison of its spectrum with the s~ectrw of a substance of kno structure. he work of Hartley, Dobbie, Lauder, Hantzsch, Coblentz, Baly and others has been of great value in arriving at this conclusion. An exa;nple will sho· more clearly the application of t is principle. he che •. leal reactions of carbostyril are s ch t' .at it is imnossi ble

0 determine whether it possesses the eto structure shown in I, or structure appearinu in II.

1 - Phil. Trans. , 1862. Pt. 2 . , -..~61 • 2 - Watson. "Color in Relat on to Cheoical Const t tio Longmans . 19 18 . p . 21. 3. - Coblentz. "Infra Red Spectra. " Carnegie Inst . 1905. - 9- J/ Jf /C H ;c- c. II c, 14 c II.. I .- c-o -oil H I .

t 0 bot 0 r 0 0 t

t

0 . . , - 20- or retard it, or to stop it alto ether. From the forego n it can be seen the general usefulness of the study of absorption spectra. For purposes of discussion, the effect o add tion of groups on t he displace ent of absorption bands can best be shown by a brief summary of the ref ect when added to benzene, as e li{e to regard benzene as t' e parent subs tance of all aromatic organ c com- pounds . Benzene tself possesses sev en bands in the distant ul­

tra-violet. On introduc ~ne; aL.. yl rou~ s , the bands apparently fuse together. Amon the di- derivat_ves of benzene, the para co -

pow1ds u ually reta:n ore of u' e be 7ene ban1s .

Halogens pro uce a s_m·l~r .er ln~ e~ ~ect t' a shift:nu toward the red; odo benzene hav ng er ed all seven ba ds co.pletely. Un aturated s_dc chc. ns ro ce an analogo ef ect . ino . In t e case of the a no co pow1ds , li{e an'li e here the n trogen h a valence of t ree, the ben e bands are all unite into one ; 'o ever ·en the hydrochlori e is re ared, so.e o ben- zene bands rea ear in the same pos on as ori n 11 oun • 1 H;y:dro! ;y:l . The OH ro p , as found n p1e ol produces a broad, deep b d , h c sh_ ts to ard the red e d , oppos'te ro an 1 ne, hen ts odium salt i repared. In the c se of p-a ino p enol, t e re rerse e feet is found :en an acld s added.

itro ro ps e erall· ca e a f son of the band , it' - out uc displace ent . ne nuclear dro en ato are s bst.:.tu- ted in n tro co nounds by OH or 2 groups , several distinct brud are produced and a ell- defined ove ent sober e· .

Carbox;y:l . Benzo.:.c acid produces a un_on in the ru

1 ove ent to ard t'1e red end le 1 the salts of the acid s1lft the

1 - Baly rans ., 1905, - 21 - bends back toward the ultra-violet . As in unsaturated side chain- derivatives of benzene, similar deTivatives of benzoic acid (cinnam­ ic acid, for example) ahaw a displacement toward the red part of t he spectrum, with the production of a broad band. As far as can be stated the usual effect of substitution in t' e benzene nucleus is to p~oduce col or by a gr adual movement of vhe absor pt lon bands from the ultra-violet into the visible. As given by Cohen1 the order of the gr oups relative to their displace-

~ent effects , follovs . The groups produving maximum displacenent

~re found on the right . CH3 , CN , COOH, OH , ONa, NH2 , N02

b . Description of the Apparatus . The study of the color of substance, by mea. s of an exa - nation of its visible and ultra-violet spectrum is accomplished by passing white light through a liquid layer conta.:.ned in a quartz- sid­ ed cell and thence through the slit of a spectrograph where the rays rass through quartz lenses and prisma, and are rea orded on t he sur­

~ace of a photogranhic plate, specially sensitized to record rays of

~igh refrangibility. or substances like benzene, for exa. .,ple , vhe spectrum appears as a ser es of long narrow bands in the far ul­ vra-violet. For the spectrum pictures wh ch roe prepared, a ilger Spec- .. rograph, size "C" , of 24 i nch focus , ·as used . As our source of

ight, we chose an iron spark. A dr aw_ng of the entire app~ratus F-PPears as Plate No . 1. The cell we employed 1as ade o!' a sect- ~on o~ vlass tubins, 5/8 inc~es n diameter. It nad a hole in the ~ide :here it was fastened on to the botto of a graduated burette.

- Cohen . "Organic Chemistry. II Pt II n AQ Plate No. /.

Bottom of Bure fte Ce /1.

L C ~------~

E A pparafu.s. £ = Iron £!ec-froqe.s. L .:::- Lens rodt"rec.+ra_yson.slif; c c e I/ . ..S = S I i-1-. P ,. Pri.5n7. A 8"' Pho f-o9raph ic Plaf-e. - P-2 - In the necl{, between the cell and the bottom of the burette, there ms a small gl ass elbow, which served as a means of e ptyi t:; the burette. The sides of the cell were made of two quartz pl~tes ce­

~ented on with water glass . The distance from the inside of one quartz pl~te to the inside of the other, or in other Tords the longt of the cell, was 13 . 8 mm . For most of the photographs, a slit of . 06 mm . openinG was used and an expos re of 15 seconds made . 'e sed a logarithmic dilution instead of a linear. In this way , e btained a spectrum at once as it would appear if plotted in t

'le believe this to be a decided impr ovement, as the

nay be plotted much easier from the d rect measure~ent of t phic plate. In our experiments , we sometimes used a two-thirds

o~her times , a five- sixths dilution, dependin on t e charact- r of the absorption produced. That is, if the bands ere rather ard to distinguish from a plate where a two- thirds d~lution had been

repeated usin ~~e slower dilution. All a ount

substances exa.. ined were we.ig h ~Zd out and the solve. t added so as

0 produce moler concentrattons . In detail, a o-t rd lo·ari h- carried out as follows : 4 cc . of t'1e solution be ng

added to the cell . .ffi exposure as .• ade, "t e plato ed, and 2 cc . o the solvent added th thorough _x.:. .. e; . Another x osure was made , and 3 cc . o_ solvent added. is proc e4~r~ as ont.:.n u.ed w th the addition of 4 . 4 cc., 6 . 66 cc . , and 10 .0" cc . , res After an exposure at the last dilutiol, the solut on of the burette until exactly 6 cc . re.ained in the eel • hen the entire ..uroc ed"'Ye il?.s repeated until ..., e posure"' b en At this point the ct-11 m:.s care nully rinsed out, an' one nore - 23 - expos1lY'e na<':.e usinc; the pure sol vent . his method of empty_ng the

cell saved cone i d ·r,, )::..o r: o1ven-'- r..., ·well c,s enabled more thorough nixing to be nade . The photoe;raphic pl tes used were the Cramer Spectruru Plate, size 4 x 10, rnade by the Cramer Plate Comp&ny of St. Louis, IisLouri . T1ese were developed in a Letol-hydroquinone developer over a period of three minutes .

c . Reproduction of Results . In the measure. ent of the wave lengths of the edges of bands on a plate exhibiting selective absorption, considerable dif- ficulty is encountered. The principle source of error arises from the choice of the point r:here the band bec;in . For our drar:­ in;:::s , we have chosen the point here the first visible absorption is to the eye. This is done by e careful comp rison of the

the solvent exposure TI th that of each of the d lut:on ex­ To decide th s po nt t. e pl te is placed on a frame and e.inst a piece of opal glass llu Lnated fror1 behind y an

light . After the points rere chosen, a l!dt line 1a

throu~1 them w th a pen, narrins the edges of t e b nd.

At the present t ~1e , the method of eYpre "'.inu conclu...,lons

to the number and o i t_on o .. bands :s by means of a cur-ve .

n the general curve, the ;o nt 11 ' n E,l!"e I s d f_ned a t1e The ordinate o tl is po nt ind cotes tne

Our curves ·ere prepared us nG for D cls e, the or o c llstion frequenc es of the spectrum at the d.i_fe

po nts . By the term, "oscill ":.ion frequency" is meant, s ~ ne it, the rec procal of the wave length reduced to vacuum. or rdin tes , e employed the logar th s of the actual th cknes· o. I . oo:£

02..£

\) 9f

o vf t.? 00~( ~ ~ ~ ~ oo- .J Q) ~ \'S Lr 5

ooc

uO

·;;VI/ ;/.':J p.-topu 16 .r-~ t.vo.A;r. -'"--'--,' D e..n.,t.u;:; "'.' a?c.-b.f-"~0 ~ ~ ~ ~ ~ ~ - 24- of the sol utlon as calcula. ted f'ron our dilutions . On the rie;ht hand nide of each curve will also be fm.md the relCJ.tive thickness usine; 1000 as the basis of our first exposure . In deterElininc the wave lengths of the points, it. was foun that use could not be made of the scale on the spectrot.;r?..ph as an adjuctrJ.ent had thrown _t out . .'le therefore ran a plate of several metallic spectra, such as iron, copper, cadniun and zinc . ilorkinc;, after t he me thod of Baly1 with cadm un line , wave l en e;th 5086 .06 which is practically identical, for y>urnoses of .oeasure:nent , with iron line 5056 , cad:Jiun lines uere chosen r1 th the· r res:rective we.ve len~tlls , e.nd t he distance in centiDeters fron the stc:mcJn.rd line was fotmd . These two ficures , the wave lencth and the dlstance in ce1 tineterr.. ,were plotted us ng the latter as ordinc-tes and the ormer as abscissae . This curve appears as Plate o . 2 . Then, on pre- paring a curve of the absorption spectrum af a ~ubstru1ce, the d_st­ Rnce froB the standard line to the edge of the band was measured in centimeters nd by referring to our curve, we could read off direct- ly the wave lengths . To convert the 1ave lengths to oscillation req_uencies , we used the table of Dr . N. osanoff that appears fun Plotnikow' s Photochemische eroucl technik" on pa-e 3 O. In this way , a curve that faithfully represf:nts the alJ"'orpt.:..on and is pro­ duced .

III . Diphenylamine, Carbazole ane Several of their Deriv tives .

Disc ~ sion of t he Curves . Introduct.on .

n 1 r. _J·r • "Spect!'OAcopy". , p. 134 . - 25- From the discussion which was talcen up in the first part of [Lhe pa.per, it is not out of place , at this point, to make a few pre· dictlon& . The only one of the e;roup of spectra prep... , red that had oeeP ru.r: l:.e :'ore is tnat of Diphenylamine . Therefore this substance !will not be considered here . We would expect, however, for carbaA· ole!a spectrum influenced by the combined spectra of benzene, indol, and pyrrol . The first and last named had been run, but the second substance had not been examined. Pyrrol has only general absorp- ltion, while bene.ene , as stated before, possesses seven bands in the

~istant ultra-violet , the nearest one to the visible, having its heac

I ~t 'X 3710. Therefore it could be predicted that the substance, indol, which is a co bined benzene and pyrrol rinc, would have quite

Ia disti n~ t band, the head of which r.ould be shifted over to. rd the tvisible . Further, on adding another benzene ring to the indol structure, it vrould be anticipated that the effect would be a widen- ing of the band of indol, caused by the distant ultra-violet bands of the additional benzene ring, as 1ell as a further shift toward the visible .

On adding the nitroso group to the positlon of diphenyl- amine, it could be thought that a shift might be produced in the one large band that this coopound has , along ith e appearance of one or two bands in the ultra-violet due to the influence of the group itself. If the group exerted , enough influence to move the edge Pf the band just into the v sible, it could be predicted that the

~olor of the result ng compound ould be greenish yello to yello • Ppon preparing the para derivative, a deeper colored compound would Probably result, whose spectrum should differ from the N-nitroso forrr Results similar in character would be predicted for the corresponding nitroso derivat ves of carbazole . With the nitro group, however, we vrould expect a stronger shifting effect • . • In the first place, the substance would no doubt be more highly colored, as absorption vmuld be expected to con

tin~e over as far as the blue or blue-green part of the visible, which would produce an ora.nge or a red-orange colored cor.1pound . The spectrum of this compound would probably have s everal bands in ad4il..; ition to the one large band extendinG partly into the visible . In the indophenols, where a large colored "nolecule has been added (P-Nitroso Phenol), the absorption would be expected to extend

over into the yellow or orange, with ~e product~on of a substance yielding a reddish-violet or indigo solution v1hen dissolved in alco-

~ol . Again, the influence of the spectrum of the group added 8ay be so great as to partly hide the effect of the diphenylanine or car­ bazole radicle .

With these proPhesies in mind v1e will nov1 discuss the re­ sults as actually obtained.

a . Diphenylamine. The spectrum of this substance had been pre ared by two

~nvestigatore . 1 It was decided to run its s~ectrum , however, to be able to check up otir instrument . Ex min tion of the spectrum,

pf diphenylamine, appearing in Plate ro . 3, sho s that general abso~

.uion begins at abput ~ 3100, and extends in a rapidly falling curve

~til the head of a band appears at ~ 3535 . he logarithm of the

~ctual thickness of a 4/2QOOO solution at this point is . 9435 • The t-esul t compares favorably with that of Bal{er published in 1907, v·ho -Baker. Trans., 1907, 91 , 1496 . -- Purvis and IcClelland . Trans . 1912, 101, 1517 . Osci!lol/on rrequencie.s . () 0 0 0 0 0 0 <:> 0

8oo Pia t-e No.3. Dt",Phe.ny/ arn/11e. 6oo .~... 0, ~/0 :r 0 r/) 0 ~ . o 0 4oo 0 () li ll

I;)

II) II) \J t ~ t-oo ' (/) "l () ~ ~ t 15 ~ \) . ....0 ~ ~ ~ ~ /0 0 \) ~ () i: (l Ill ...... J ~ '

/.0 Osci//ahon Fr-~~" en ct~s.

t.~ Q () () <:) 0 ~ <:) 0 ~ 0\ ....."' 0 <::) ~ rt) ~ ..... & ~ ~ ~ ...,. I<) ;:s "t ,foo

Plqf"'e No . 4. Indo/.

~ o-r,·~-~ ,t'l '-IV"c -+1 l ~0 'R II ~ 0 ito ~ 0 0 ~g ~

100

~ t')

I') ~ II) ~ \) t ~ 1.5' ~ 50 .,

tJ u .~ ~ ~ ~ ~"

~

~ ~ t.S"

\ I ~ /.o I \ , I) ' ./

/o gave as the head of this band ~ 3550. Purvis and .cClelland in 19 1 stated that the band had its head at V,. 3560. All results are compar able . The curve rises to a peal{ at V/.. 4005, Log . Thiclmess 1. 822, and from that point falls gradually toward the ultra-violet . Di­ phenyl amine can be said to possess one deep, wide absorption ba~d whose head is at v,_ 3535.

b . Indol. Before entering into the discuss on of indol, the spectrum of pyrrol will be briefly ment oned. The structure of these two substances is usually represented as s1om.

~ ,~, H-e - c - 11 ~< , _ t -Il M I I J I ti-C e- ll ..... 'If' tiC~ / <:.-.... /<:.-rl 4 ~ ti,tl Pyrrol. Indol . Hartley and Dobbie1made an ex~minat'on of the spectrw.1 of pyrrol in 189 . They ca e to the conclusion that it posse sed strong general absorption but no ab orption b d . Absorption was complete beyond

'/}.. 3893 . Later, in 1910, Purv s 2reported on the same b tance . He fotmd no bands in the ultra-violet, and general ab orpt on appear ing beginning i th 1/). 3781 . It is interes ng to note that al- though thi substance had no bands in the ultr a - v ole re5ion, Cob­ lentz3 found a hand in the infra- red a 2 . 94 u . The curve for Indol, l te o . 4 , bear out our pred ction that it should have quite a large b nd transferred further into the region of longer wave- leng hs . It as found, on care ul examina- tion thnt there are re,lly to bands, instead of one . These ay be 1 - Trans ., 1898, 73, 59u . 2 - Trans • , 9 10 , 97, 1648 . 3 - Astro hys . J ., 1904, 20, 207 . l O...scil/ai-ion ;=Y-equencies. 0 0 0 0 0 0 0 { ~00 ~ ~

/..o .o~ 4oo -i: ' c L

;z.oo

0

V) ;.S V) \>

/00 v." QJ

\)

5o

/0

Pia 1*

c . Carbazole . In the curve for carbazole, we find four distinct bands . The two bands of indol are still present , but they are not separated nearly so much as in the spectrum for that substance . Examination of Plate No . 5 shows that the heads of these two bands have been slightly shifted. They appear at y,_ 3424 and V~ 3 56 5. The persist- ance of both bands s the same; Log. Thickness ~/30poo , . 625. Two ew bands have made their appearance; one, very near the visible wit its head atX3105, and the other, caused probably by the benzene band in the ultra-violet, ith its head at v~ 3864. The nersistance of these bands is Log . hickness 1. 4 0 and . 9785 respectively. These results are som hat in accordance ith the predict ions . The large deep band, rhich is d i vided into t 10 parts near it is the band that was anticipated. The s all band in the re- _on of the benzene bands is probably the result of t:1e merginG of of the extra benzene nucleus added to indol . e • expected band a~pearing so near the visible may be thought to be reasons that carbazole is prov ng to be so good an nter- It is almost near enough to pr.oduce visible color. As wi

e mentioned 1 ter, the color of the nitroso derivative may , no daub e traced directly to this band. It should be nentioned that car-

azole shows a beautiful v olet- blue fluorescence, especially marked hen in alcoholic solution. O:sc.- i 1/a f-;on Freq (..( e r1c i e.s. 0 0 ... 0 0 I) 0 0 0 0 0 0 0 "0 () (( 't t'l') 3oo 0 ~ "l If)"' 'oj. ~ !'f) ~

ZoO Pili~ fe No. 6. N- 1'1/froso - Dlphenyl ~ arntne. 0 ;..' /.S N~ ~ o...... ).; - o ...... 0 V) JOO 0 () ~ 0 <5 II)

~

0 .So ~ d) ~ /.o t ~ , l,) )'\'

'll ~ u

"\) \ ~ / ~ ' ' ..... / ...... ______-- .5

Q

II) t :-R ' ~ ~ 0 0 0 0 0 0 0 0 .....0 '.

' ~ ~ , ,I ~ t\: . ~ () ' ~ . ~• '' .. (lJ I ~ a' II) ~Q () ~ ~-x: ~ ,.. ~ I 13' ...... 0 'Q ~ I Q

., 0 007f

I I OOOf I I I \

t;)

OOG>~

ooo~ - 29-

d. The Nitroso Derivatives . N-Nitroso Diphenylamine . On preparing pure N-nitroso diphenylamine, it was found to

be light greenish_ yellou in color, substantiating the predictions . The curve for the absorption reg1st£r:ed by this co .1 pound does not , however, w!1olly agree with the predictions . In the first place, it is very much l ike the curve for diphenylamine , with one apparent difference ; that is, the· main band has been considerably widened, as it now extends over into the edge of the visible blue violet . The second contradiction is that there are no small bands anpecrine; in the dlttant ultra-violet as was thought ight be the case due to the influence of the nitroso group itself. The head of the band has

been moved slightly, as it now falls at 1,~ 3420, with the Log . Thick-

ess , , 516 . From the peac at V~ 3930, the edge descends sharply, into the far ultra-violet . e curve apnears as Plate o . 6 . P- itroso Diphenylamine . The aniline type of rearrangement which occurs when the ni troso group is shifted ar ound from the N position to the para nosi­ tion ap~ears to exert a strong influence on the color of this com- ound as it changes from the li ht yellow to a deep blue . The cur

this substance, re resented by Plate ~o . 7 , sho IS the effect of he strong absorption in the vis ble as the most prominent band is

with its head at ~ 2400, Log. Thickness , . 894 . The band is

arge and 1ide, rising to a peak on the right at ~ 2984 . From that oint, it descends in a gradually falli curve until another soall

and is produced with the head at~3542 , Log . Thickness , t078. This

and is followed by another, slightly deeper band at ~ 3625, Log . hiclmess , , 898 . These bands may be the ultra-violet bands which Osci IIcrf-/o n Freqc..(encies.

0 0 0 0 0 0 .. 0 0 .. 0 0 • Q ~ "t- ~ tol I'<) •" "' <'I "l ~ "'t" -t

Sao

~.() 4oo . ~ ~ ~ .3oo ~ 0

~~ ;!oo t.:> ~ t:l \ ~

!~') II)

\: /00 ~ . \l ,. ... -...."'\ ~' 1~

\ ... ,_,, "l;l ~ .s'O ~ ~ IJ - ~ "\ lo '\...' Cl ' It

Plafe No.8. -30- were predicted for N-nitroso di- phenylamine , but did not appear. Tha is , the effect of the shifting of the nitroso group around the ring may be that of allowing it to exert enough influence to produce the tTio bands in the ultra violet . N-Jitroso Carbazole . When this substance was prep<::.red in the pure state, it v:as found to possess a beautiful golden-yellow color, much stronger than the color of the corresponding diphenylamine derivative . As was briefly mentioned before, this difference in depth of color may be explained by the fact that carbazole possesses a band nearer the vis ible region than does dtphenylamine . Therefore, it would probably be more deeply colored than -nitroso diphenylFoine , which is the case . The curve, as drawn in Plate o . 8, shows the presence of three distinct absorption bands . one of them are very persistant, at least not so much as the two most proninent bands of carbazole.

The heads of these bands are found at 1/-..,.. 3038' v). 3580' and Yl 3 88 r espectively. The persistances expressed in the sane order, are 1. 270, 1. 168, and 1. 034 . The edge of the band rises into the visible on the left on a rapid a cent . The l ast band on the ri< is apparently the sa e one as appeared in carbazole . An attempt '\ia made to prepare the P- a troso Carbazole, but _ t did not me et with success . e . 0-! tro Diphenyla ne . Relative to the color of 0-nitro diphenylamine, it was found to agree closely with predictions, as it was reddl sn-oranve . In other words, the nitro group uust exert a stron·er shifting in­ fluence on the absorption band in diphenyla ine, than does the nitro so uroup . On neasurement of the p oto0 raph and construction of 0 0 0 0 ..... ~ ~

oo,.f

OQ'lE Cl,) .~ u / I ~ I \) { ~ \ OOOf ~ ' ' ~

t 0 oog? 1-: ~ ... ~ Cl)

QOIIJ'/

' 'I I' I I

0001

.r!JO/_LIe band in the visible is not as persistant as either of the tuo saa:..ler ba.cs, as

the persistance of the la.r0 e b d is 1. 590, 'i1ile the two s. a_ler, a. hese two 1. 120 and . 920 respect_vely, 0 oin0 from let tori· t . s-a.ll bandn ay be due to the i fluence of the a.uxoc11rome, as t was suggested in t' e discussio. o P-I i troso Dip. e yla ine . An interest · no f a ct about the curve Ol' 0-ni tro d p'1enyla. ine ls that it is al ost identical with t· at o P-n troso dlphenyla ne . . Several unsucoessful atte~pts er e ade to prepare the ni- tro derivatives of c rbazole .

f . The Indophenols .

he str cture o the indo henol of di henyla ne s usuall ooked upo s 0 O•N Q =o '-N/ I H en prepared pure, in t e dry state, it is a very d r blue in color.

solution it is a deep indigo under trans itted 1 · t . he addition of the gr oupin , p- nitroso phenol, has apparently pro- uced a l arge displacement in the absorption bands . The curve for -n troso p'1enol, prepared b Baly, Edwards , and Ste art appeared in .g I · "> \ oog(' \ '------....._-...... ,, / ,..- ~ ~ \ ---- C) ...... ~ ...... c ...... C) ~ <:) t ...... ~ ~ ~ r ~ ~ Q,_~ Cl ...... \ OO"f'£ ~·~ Q. ~ <:) ...... \ t ~ I \\) ...... I 001!£ I ~ ~ ~ ~ \) OOOf

\)

oog~

......

IJ' V) () oon . / I I I oo~z I \ \

ooz"

00071 - 32-

1906 . 1 It shows two pro· inent bsorption b nds ; one at 'ft... 2650, an he ot' cr at Y}.. 3760. The irst h~s about t 1 ce t1e peru stancy of t e second. Therefore, rhen "the larc;e band of diphenylrun ne is

s b nd, t· e e~ t io a ar~ed shkfti g of both b·nds far added to t fl over into the vis . ble . he c e for th.i.a subst nee, Plate o . shows this fact qu te clearly. On the left hand s de, there 1~ of a large b nd a nearin in the visible. Its head 1ould prob

be at ~ 1~50 , h.:.ch is the sa e as 1-. 5405. ro1 t _s po_nt. , curve ascends steerl y until a pea'. is reac ed at '/). 2 2 , or e ·e of t e v.i.slble. he next band is deep ana • de , and has

he d t Y1-. 3 ~ 30 , w th a ersistancy for a ·:/15 512. at ..... oc. M

1. 506. A short distance beyond this d , another, sc

d akes ts a pear'-' cc . T e head is t 1/}. 3728, t1 Loc. hlc

1. 615. he rl t h d s · de of th.:.s band S an al oat vert ca hlc es :n·ch tur s shar ly to the ltra-v.:.olet t ::.o . ' "'"' · the curve, tcan be seen that the effect of co.bin t·on o as been a lar·e s.ift_n of the bands of bot co • ounds . I doo· enol of Carbazole. T e structure of th s substance be consldere a ho

owdc.rad ... or , hen pure, the indo enol as of a very dar- lu a - red color. It ·ave a ·ne- red color in alco ol c sol t•on. solubility as only abou · alf that of the indophe ol of d·phen 1 On preparation of the absorpt on curve, as s in

o . 11, it ap ears very uch lie t' e curve forte ot er indo~ 1 - Trans . , 1906, 89, 502. ,..,0 ~ ''-...., ' \ I I ) ... / --~ "\-.. ( 0 ...... _ 00#)£' - ~ - 0 ...... ti ' 0 ----- , ~ s:: ~ ~ ~ \ ~ i.... ~~ \ \::! Q.. ~ ...... \ a. ~'-'v I ~ I I I ~ I Q) I ., I u OOZf I I \: / ~ / ~ ~-----.... c;} Q) \. ooof

~ . C> ' ~ oogz ~ 'll C!) .\J I 00?:1 I I I \ \ \ oo~~ \

ooz~

0 00"'1

0 ~ 'LtOf-f17jO~ 0000?£w -3.3 - There is the same gen eral appearance relat ve to the nt - er and position of absorption bands . The distin uish n differenc is foQ~d in the persistancy of the two substances . The indophe.ol first discue.sed possesses the s t ronger persistancy. In this indo

henol for carbazole, there is a lar0 e band in the visible wh.:..ch pro bly 1as a head at about 'h. 1900 . Two other bands are found, both n the ultra-violet ; the first at 1/~ 3350 , and the second, less per-

istant band at v"A 37~5 . The persistancy of the for. ~r ( Substance s /360000 ) is Log . Thickness 1. 71 and the latter, , . ... 2 .

Summary. In general, it .ay be said that the curves as found bear

facts . he nitro roup appears to po sess a stron er in

on the displace~ent of bands to the le t or vis ble art of han does the nitroso sroup. A para shi t of the nitroso roup_ g has qu tea poTerful effect on the olec e, as ·t be- omes more deeply colored as a result of this rearran e ent . In t ndophenol , t' e spectra arc so much al e that it m.:..ght be thousnt

s manly t 1e added 0 roup hich is produc n the ef~ect . The o spectra resemble, in a _ar e eas re t' e spectr for p-n troso henol, so that this fact furt' er po_nts to uch a co1clu on.

IV . ExperiQental ork.

a . Diphenylamine and Carbazole.

S ~les of both these substances, in a ver pure condition obtained fro .erck and Kahlba , resnectively. Upon taking

0 • e melting points, diphenylam ne gave 54 and Carbazole, 23 The onclusion reac ed 1as that they ·ere sufficiently pure to run spect- - 34- rum photo3raphs of. Solutions 1ere prepared, such that the di- phenylamine was 1/20 and the c<::rb:t zole L/30 .

b . Indole Purification. A tan colored s le of indol resisted attempts to purify it when several different solvents rere used . Finally, it was de- cided that water might dissolve it. A small amount dissolved read- ily in water, was boiled with animal charcoal, and filtered . It

0 yielded beautiful v:h te, leafy crystals meltins at 52 . 5 • About

alf the sa. ple was treated in the same ma~er and the resultinG

urified product used for a p 4 cture . An arount equal to . 097~ gas was dissolved in 25 cc . of alcohol . ' is solution vas :~/30 .

c . - itroso Diphenylu ine .

Follow_ng the method of E. Fisch~r, 1 this substance was pre pared pure in the follo nG way . 15 grams of diphenylamine 1as dissolved n a cold ..tixture of 100 cc of alcohol and 9 cc . hydrochlo ic ac_d (Sp . Gr ., 1. 19) . To t hi:J solut_on \7as slowly addec 35 parts of l aN02 (conta n_n · 2 %. 203) in a concentrated solution (2:3) . ilit cons~~~t stirrinG, the liquid first appeared a dark brown color and ater beca e a light tan . After t:e react.i..on had apparently

eached ru1 end, the yellow, ranular crystal~ o~ the nitrosa : ne wer

iltered o_f rith s~ction , ashed wit alcohol a d wa er, a d dr ed. ater re oves any salt that rna· be u.:.xed nith the cr·stals . All f the product obtained as recrys al zed tl_ce from hot li ron and

arefully dried in a desiccator. _ e cry~tals ere Qranular in forn,

() fa 1 ·ht green_s. - yello color a1d melted at 66 . 5 . An /30 o_ ttion was prepared b dissolving . 3304 g " . · n 50 cc . a lcol ol . 1 - Ann . , 190 , 17 4 . ( 1E78) . 0 nyl n . e ll-n·tro o n , u n tr nt i olut on

1 ohol t ra ed ' th dry 101 g s U."ldergo ' l ' n t 0

ent, 1 er n the ·zo ro from to the pnr ollo ·ne the c! f ...., c er 1 ut 3/

tho ount o the co 0 h left . t d n hi leo ol olut on o roge c 1lorlde d by ener "' ng dropp ' n u1 .ur'c c'd thro · a or f 1 n o

1 , the r of c lc ·nto c lc c lor~d u

hone b e n 0 gl t bn to ho urf c 0 1e alcohol . I

"'llo e to t 0 hour e ol t on n cool c

cry t 1 0 ·-nitro o 1 co -

t t rr m e color c ro 1 to r· r d 11 h e 0 h - ro roc r

z 1 1 c rc allo d to z

0 0

1 r d c

0 I' ol 0 c J.oro r 0 0 ' r 0 coo c 0 c I ol on r r so . 3

cc . 0 a cohol. . . e . - ro o r zo le o c tro o e, pre re b one o h tu nt n he 1 a re

2 - cryntn. ize- from hot ether olution evcral 1m&& . f.i.1.:lly o t..,·ned 1ere a -olen yelloH 1 color a.nd 1 elted arp y '""t

80 .~ 0 • A ./30 ~olut_on ·cs prep.... red by dissolving . 3269 ·ra. n

50 cc . of alcohol, and m' used for t he picture.

f . P- itrono C~rbazole . ollo ring a rat 1e1· nea er account of prepa!' tion given hy Schott1 an at t e~pt vras ~de to nrepnre p-nltroso c rbazole. The i -nitrono c r r~ _e .rr ~dded loay, th constLnt st · rrinc to ! 50 cc . 0~ glaci 1 rc etic ~cl- "'he f:'olu · on ·a cooled by allow ng to stand in cont,~c r' th ice. About one :t..i.nute after all the aol · d : added, tae ent re aolut_on bee e ddenly th c -:: . The color changed from a yello. · h-gr en toad rk r din about f ve m: utea. Upon f:lter.;.ne; d s l g ' th .ater, t e turned light green. The "'' ... , hlch .. e up oscd e had, a d · ,... solved n dilu e alk 11 { aOP) . ~ e color chan ed ed ·tel. to

·eak cetic ·•cl ~ a , d 'ed tU :_ he ba. neu rv. iz T e 1 , plec · patste that .1.or ed.. fllt r 1 rou ilth c;. t r , anc. recr st llzed :'rom hot alcohol . r e cr t·l e 0 yello in color ana nelted t 2)3°. on recr t a · froo benzene, n the presence of n 1 charcoal, ure lte, 1

ere obtb.' ned, 1 c h . e 1 d ... 23 o. cone uded

.L ·:cL 'lad hydrolyzed o f the : -= v ro 1. u e d ob- lne c · r zole as or ' nal roduc •

. o-:- tro iphen 1 m .•e .

In the preparat:on o o-n1tro i~ en·-a ne , ue dote th s_ ' ght modi ic·t on of hrf1ann nd Hava. "2 10 - Che:. Zen.Lra . , S 2 , II, 116- . 2 - Ber. , 1 13 , 46 , 341 . - 37-

f o-n tro chlor benzene which hcd been recryot· ~ed from lcohol,

13 . 8 cc . 0 n 1 ne, end 5 , 2 gB . o ~nhydrouL sod ua acetate w~o ne ted n a round- bo+,to aed fl<>ok \Lth an air conden. er, ·bout 14 hot in an oil b"th. The te.. per ture, dur ng t:1i tl e wa 0 215 • Instec. d of ~·te . d tilling the as as su ...;estec b·r the aut or..., , 'he d .. r \: brovm oily solid :raC! treated with 20 cc . of 1C ~ acetic acid soJ.ution nd thorouf).1ly ha {en. After tru d ng over

the acet_c ac.:..d. conta.i.nln so e Lline, !'1 cecanted o f nd

ever 1 t_ es. The oll as ullo~ed to run int ncl evapore.t.:..nv dish and \",ashed a in th acet c and fi ally

r ter. ~he .hole o s~ was then d s olved n aloohol , heated

bone charco<~J. d ~ ltered. On ·llo ng the f ltrate to t~ These oro reciy t· l 'ze froc hot alcohol, from hlch the a- nitro d henyl· ne cr cta_ · ze~ out n gl. clng redd •i -yello lea~le s . On c·re 1., dr · nB , they

A /3 olut ·on 1· re r d by d.:..ssolv n cc. of .... lcohol .

h . 0 -. tro Carbazole.

Sever 1 ctt.n~t to pre r 3-n ... ro carbazoles , c ere upposed to coae fro t e c e e. er_ ent ccord n to Ziersc . All tr- ls ' elded t" e e produc~ . B r1 - sent ' ally t e proccedure ollone s 15 r s o~ car zole as u ende n 20 cc . of glac ·1 ce c ac ' d , to hic'1 TaB added

by dro ~ . 33 cc. o~ o, Sp. '!.r. I •.38 ~eo n the tem er ture t about '"'Oc • In one exper ent, the heat n • s to ped t this

o'nt, hile in ~not1er , it .as cont.:..nnued fort ree nours ~rter ar 1- 3er. 19 9, 42, 3797. - .... 8-

The yield was the s me in both case~ and the products p eared to be the sa c . he suspens on turn~ dark bro m and upon cool ng < yel- lowish-hroi';n substance separates out which accorC. ng to Zier ch, elted at 205J . The o-n tro carbazole w· s u.pose to be ob- tainable from the filtrate upon additon of mter. Accordin to 0 the author, this substance melted t 164 , after cr· ~tal nz ng in fine yellow needles from ~lcohol . The precipitate from the nitra.t.:.on mixture (..,upposedly 3- nitro carbazole) was added to 20 cc . of alcohol nd he~ted to bo 1- ing. It was then fil ered and the undi solved nart added to ore alcohol . Fro. the filtrate of the first filtration, there as ab- talned a crop of scale-like tan colored crystals . From the other cry~taliz t:ons, t1ere 1 s obt ined needle cryctals, scales, nd po1 dur. 11 ··ere ligh brovm n color and all mel ed .:. thin

229- 232 . 5° . Evidently the com.ound --a dif erent ent rely fro. that obtained by Ziersch.

1he precip ta+e , ~or ed on add t·on of ater to the f fro the ni trat.ion r.1· xture (stated by Z · er"'c . to be 1- n · ro car zole), a dissolved n alcohol, .ilterod d allowed to tand. a peared darlc-brovm ro ette··li e cr t 1 h ch ormed s ort- 1t bro A melt'.g pont .a r 0 eac •. he d rk brovm ro ette cr ct ls elted at 197 d t e ligh bro m or yellow crystal at 'c:; " . ar· ou olvent ere tr.:.ed on these to see 1 [' se. r t'on could · e bro1ght about . e1zene see ed o d.:.saolve the ligh bro.m cry ta s . On boi_i u in be zenc nd ryin:.> everal t es, ,he eltlng oint .as found to continnu lly l e or:: had to be dro ed "t th s point in rder to continue the ;or· on the do 1enolr . - 39- 1 . P-Nitro o Phenol.

An none of thi substance v:as found available, it as pre-

after the I!lethod descr bed _n . ·eyer and Jacobson 1 using slight .1od.:..ficat.:..onn to pur y the product . 60 gra. s of phenol were dis-

~olved in 12 0 cc . of water. To tlis solut.:..on was added , solut_ons

of . a ro21n 150 cc. of ruter and 27 r~ .. s HaOH in 150 cc . of

The beaker containln the solut.:..ons 1 n urro ded by an

1 t .. ixture. en the tern. eruture had beco. e 0° , a ..xtur err s of sulphur_c a.c.i.d and 4CO cc . of iater added to the

rst elution slorly th cont_nuous ~t-rr_n~ . After "t d.:..nu

uo hours, the preci.~:.:..tate or ed ~ 1 tered off, 1 • hed thoroushl

ice water, and t e .hole di ol•ed in 50 cc . of ra er b addi-

of 40 cc of a.OH solution. (a~ded drop b dro .i. th tlrr.i. . ._;)

del n about 8 ra.. o:: Fuller' a rt , the hole a tirred in tes .i.th a echan.i.c 1 ot_rrer, , ereu on it :a filter

th sucti he ~1 trate ~s trea'e"

· r.. Cc: r ~ull:r i th con tu.n t t_rr ng. e p- n1Lroso p e ol

eparated out al ost h 'te ~t first, b t ra ly dar.ened to a bro m

a short t me . ~as ~iltered o:: ao ed oro ghly and n a des·cc tor. It as ro po aer hich on ex na on 0 ' cro co e proved to be cr t~l ne. It el ed o.t 130 i h osltlon.

j . Indophenol of D lenylam·n

s both t e indo '1enol ere re "re r. exactly the s me

only one rep r tion, t1at o the ndop enol of dip1enyl~ ·ne

be descri ea. . The oethod follo ed · s .:..ven in ~riedl der; 1 eyer an Jacobson. ol . II. Pt . 1, p . 457 . 2 - Friedlander. , 9 10-19 12., 1, 301 . - 4<> -

5 ra. o d phenyla .1 nc ·1ere d ssolvcd n 50 ra s of sulphuric aci '16° Be ' ) . A solution of 4 Grams of p- n troso phenol in 40 gra of sul huric ac · d was added slowly •vi th st rrin to t' e first solu-

tion, the te~per ture beinu kept at about 12°. The color turned to a deep green. The uixture was next poured on cr eked ice in an

evaporat ng dish, thereupon a blue prec_pi t te forned. Thi T filtered off · th suction, t e air drawinc; through it all night . It

·a sprc .... d upon porous plates to dry and p acet1 in c.o. vacuu desicca- tor. After leavin for about a wee· in the deciccator, as all sa ple 1as te&ted ...,.ith BaCl 2 and the presence of a sulphate detected Conversion of Suluhcte to eutral Bac( . About one-half of the total auount an treated \.·th soclum acetate solution on a stea. bath. A. purplish- oro.m solution m for.ed. The solution as filtered and the res ' due dl solved in ace tone ·ith the production of a dec blue color. hi as he ted and

ltered. o t e ltrate w . added ust eno ater to roduce

precipitate and then ' t a set a id a~d llowed~ ~ crystal of solution. The crystcls, hlch .ere very inely dlv: ed

ere d ' E> olved n ea· caustic soda solut·on ~nd prec p t~ted th dilute ac tic acid, ad ilter.d.

he blu po .der obta· ned ·n a ·as dl olved in acet one solut ' on, boiled a shortt c , d filter d . A w.ll a ount of

at.er t·as a ~decl o the _ .il trate until t e f' rst noticeable rec · ta t.ion occurred, ,-hen · t ~aa set as e and allo ·ed to cry tal.:.ze out . o er so obta· ned a dried thoroughl in the air, then, ur ev

EH'al hours 1 oven at 40• • A solution de u and the spectru prepared. - 4 1- The outsta1ding differ nee n the case of tle .:.ndop1 nol of carbazol

m~ that it was a dark redd_sh blue i color after the treat .ent with sodium acetate solution .

Acknowled ·. ent .

e tish to express our apprec_ t.:.on o the . • kindnesse and com·t~sies h.:. ch have been exten(~ed to u b· t 1e me ber of the Physics Depart ent , espec ally to Dr . ate, n hose laboro.tory all the spectrum p'10tographs ~ere re arecJ . he loan of · e s ectro-

ra 11 ,