Some Attempts to Prepare Triphenylcarbinyl P-Toluenesulfonate

SOME ATTEMPTS TO PREPARE TRIPHENYLCARBINYL P-TOLUENESULFONATE,

TRITYL TOSYLATE BY

John Vincent Killheffer, Jr.

Submitted in Partial Fulfillment

of the Requirements for the Degree of Bachelor of Science at the

Massachusetts Institute of Technology 1950

Signature of Author yV ''

Certified by Thesis Supervisor

Department[ Head ACKNOWLEDGMENT

The author recognizes that his indebtedness to Professor C. Gardner Swain for his endless patience is greater than he can repay, Table of Contents

Page

Introduction ...... I Object of Investigation. . . 0 1

Apocamphyl Tosylate ..

Past Attempts...... 1

Phenylcarbinols ......

Trityl Tosylate ...... 2

Displacement Synthesis . . . 0 0 3 Esterification Synthesis . . . 0 0 3 Difficulties of Esterification . . . 3 Side Reactions with Amines. . . 0 0 4 Separation of Alcohol from Ester. ... 4 Sensitivity to Water...... 0 0 5 Other Tosylation Methods . .. 0 0 5 Silver Tosylate-Trityl Chloride Reaction 5

p-Toluenesulfonic Anhydride . . . 6 Triphenylmethoxi4e-Sulfonyl Chloride 6 Reaction .

Acid-Alcohol Reaction . .. . .0. 7 Acetyl Tosylate ...... 0. 7

Results and Discussion . . .. .

The Tipson Procedure...... 8 .. 8 Ditrityl Ether...... Tritylpyridinium Chloride . , . 00 8

p-Toluenesulfonic Anhydride . . . . 10

Triethylamine ...... 0 11 Page

Water Reaction ...... 12 Silver Tosylate- Trityl Chloride Reaction . 12

Alcohol-Acid Dehydration. 12

Experimental Part ...... 14

Triphenylcarbinol .. 14

Tosyl Chloride ...... 14

Benzene ...... 14

Pyridine . .... 14

Petroleum Ether. . . 14

Chloroform .. .. 14

Acetyl Chloride...... 15

Benzenesulfonyl Chloride. . . . . 15

Anhydrous Oxalic Acid. . . . . 15

Triethylamine . . . 15

Silver Oxide...... 15 Silver Tosylate. . 15 p-Toluenesulfonic Acid 16

Trityl Chloride. .. . . 16

Ditrityl Ether ...... 16 Trityl Tosylate. 17

Benzenesulfonic Anhydride . ... 18 Trityl Tosylate...... 19

List of References...... 21 I

Introduction,- The present project was undertaken with the object of developing a general method for the synthesis of sulfonic

esters of tertiary alcohols. Only one such ester has been reported in the literature, viz., 1-apocamphyl p-toluenesulfonatel. This

compound was prepared in 34% yield by heating 1-apocamphanol with p-toluenesulfonyl (tosyl) chloride in pyridine for twenty hours on the steam bath. Its recrystallization from 50% ethanol gives

some indication of the abnorm&l properties of this substance: an

open-chain tertiary tosylate would be expected to hydrolyze very rapidly.

Attempts have been made by several workers to prepare tertiary

sulfonates. Heating t-butyl alcohol with tosyl chloride in pyridine at 1000 yielded only t-butyl chloride.a Gilman and Beaber3 reported "several unsuccessful attempts" to prepare the tosylates of t-butyl alcohol and triphenylcarbinol. The method employed by these workers for several other esters, and presumably also for the tertiary ones, was the addition of powdered potassium hydroxide to a mixture of alcohol and acid chloride in ether solution at temperatures not allowed to exceed 40*4 These three articles are the only mentions made of such compounds, except for the asser- tion of Tipson5 that he was not aware of reports of any sulfonates of tertiary hydroxy compounds.

Preparation of the sulfonates of even primary and secondary phenylcarbinols, e. g., benzyl alcohol , phenylmethylcarbi- nol 0, and ethyl f-hydroxy-F-phenylpropionate 1, seems to present especial difficulty, as evidenced by the hardships encountered in early attempts. The tosylates of the two secondary carbinols are 2 too unstable to be isolated, though their reactions can be studied by forming them in the reaction mixture by oxidation of the corresponding sulfinates. Benzhydryl tosylate has not been reported, and experiments by A, J. DiMilo1 2 also indicate that its synthesis may be very difficult. Triphenylcarbinyl (trityl) p-toluenesulfonate was chosen as the model compound to synthesize. The reasons for this choice are briefly set forth below.

Triphenylcarbinol was selected because of its ready availabil- ity, its complete lack of o(-hydrogen atoms, and because trityl sulfonates were desired for other research. Its structure pre- cludes dehydration, which could become a hazard with t-butyl alcohol, e. g. A tosylate is, in general, to be preferred over a benzenesulfonate from the preparative viewpoint, since it is more likely to be higher-melting and easier to crystallize. Some representa- tive melting points are presented foV comparison in Table I. Table I

Hydroxy compound M.p., tosylate M.p,, benzenesulfonate 2 6 2 7 2 8 Methanol 28013 Liquid , , 29 30 3 1 Ethanol 32-3*14,15 Liquid , , Phenol 94-5*16;95-6018 34-5*; 35* o-Nitrophenol 810 19;81.520 75033 p-Nitrophenol 97-97*5*2l 79-85*33; 82034 o-Cresol 54-5*18,22 39-40*35; 35-6*22 m-Cresol 48022; 51018 45022 p-Cresol 69 -70* ;67-8*243*' p-Naphthol 125023 105-7*36 Guaiacol, 85024 80*38 L-menthol 97025 8038 I

Displacement of a tertiary halide by a metal sulfonate was re-

jected as a method of synthesis. In general, the polar solvent

necessary to dissolve ionic sulfonates is unsatisfactory for

tertiary halides, they being reactive toward it or insoluble in

it. To this diaadvantage may be added the fact that the Walden

Inversion on a tertiary carbon atom is not easy, and in the case of sulfonates, the position of the equilibrium might very well be unfavorable. Thus, it is stated39 that "...alkyl sulfonates

react (with sodium iodide in acetone), producing the corresponding sodium sulfonates as precipitates."

The only remaining satisfactory method for preparing a tertiary sulfonate seemed to be the direct esterification of an alcohol. The reaction

RSOX + R'OH - RS30R' + HX may be successfully carried out only if the following three conditions are satisfied.

1. The reaction between the hydroxy compound and the ester,

to form an ether, must be slow enough to be unimportant. 2. The hydrogen halide evolved must have little effect on the hydroxy compound or the ester. 3. The excess hydroxy compound must be easily removed. Each of these conditions may present difficulty in the present problem. Tipson's recommendation5 in the case of ether formation is the use of excess hydroxy compound and low temperatures, the attendant disadvantages being the slowness of the reaction and the waste of reagent. The second possibility, that of reaction of the ester or the alcoholwith the hydrogen halide formed in the reaction, has been dealt with by earlier workers in a num- ber of ways. Aspiration of air through the reaction mixture was used40. In other experiments, bases were provided for the acid to react with; e. g., sodium hydroxide4 , sodium carbonate , diethylaniline , and pyridine . If amines are employed, new side-reactions must be considered.

Quaternary salts may form. This reaction takes place negligibly slowly at 0*, according to Sekera and Marvel45. Another possible reaction in the presence of tertiary bases is chlorination.

ROSO2 06H40H --p + C5H5NH1 -- R0l + C 5 H5NH+p-CH C6H430

This transformation has been encountered in work on phenols4 6'4 7 5 0 51 5 2 simple alcohols4 ' , and polyhydroxy compounds such as sugars ' ,

A further complication is the difficulty of removing any unreacted hydroxy compound from the ester, In the worst possible situation, mixed crystals of the two compounds could form, as has been noted in studies on trityl fluoride.53 Triphenylcarbinol is a solid and probably trityl tosylate will also be a solid, and there exist no really good methods of separating two neutral types like this. Probably the only means available which do not involve jeopardizing the ester are these:

1. Extraction between some combination of nonpolar solvents.

2. Fractional crystallization from nonpolar solvents, e.g.,

diethyl ether, chloroform, carbon tetrachloride, benzene,

acetonitrile, nitromethane, halobenzenes, benzonitrileetc. The second of these methods is especially likely to be tedious, and the determination of the best solvents for a useful extract-

ive separation is not likely to be an easy task. The extreme re-

activity of trityl compounds towards water must be kept in mind

during all these considerations. Just this fact, for example,

makes the useful preparation of primary tosylates exemplified

for n-butyl by Roos, Gilman, and Beaber54 , involving aqueous sodium hydroxide, appear to be impracticable in this synthesis.

A solution of trityl chloride in benzene is quantitatively hydrolyzed by a brief shaking with water in a separatory funnel 5 5 and trityl tosylate should be even more easily hydrolyzed. For example, ethyl chloride is hydrolyzed by heating with concentrated alkali in an autoclave at 125056. Ethyl tosylate is saponified

in a comparable length of time at room temperature in a 30% ethanolic solution containing a trace of sodium hydroxide57 Other tosylation methods include the following:

1. Reaction of silver tosylate with trityl chloride.

2. Reaction of p-toluenesulfonic anhydride with triphenylcarbinol.

3. Reaction of sodium triphenylmethoxide with tosyl chloride.

4. Removal of water from an equimolar mixture of p-toluenesulfonic acid and triphenylcarbinol.

Silver salts usually lead to effects different from those of sodium salts, because of the participation of the heavy metal ion in the reaction. The silver salt of p-toluenesulfonic acid might succeed where the sodium salt would not by virtue of a prior front-side attack by silver ion rather than a Walden Inversion

on the highly hindered trityl group. Trityl perchlorate58 and ditrityl sulfate59, 6 0 have been prepared by reaction of the silver salts of the appropriate acids with trityl chloride. These

acids are of strength comparable to that of p-toluenesulfonic,

giving promise for the trityl tosylate preparation. The anhydride of p-toluenesulfonic acid would have an advan-

tage over the chloride in that no chlorination could take place. A drawback in this approach lies in the difficulty of preparing

the anhydride itself. No really satisfactory synthetic method has been evolved for this type of compound. Shepherd61 rejected older methods for preparing this type with the statement that

they gave "variable results." His own procedure could not be

duplicated by Miller nor in the present investigation, even though several attempts were made. The reaction used by Meyer

and Schlegl 6 3 for the preparation of p-toluenesulfonic anhydride

(reaction of thionyl chloride and p-toluenesulfonic acid) gave

large proportions of chloride as well as anhydride; moreover,

treatment of methanesulfonic acid with thionyl chloride has been suggested as one of the better methods of preparing methanesul-

fonyl chloride 64. It seems quite possible that one of the original methods may be the most dependable yet published6 6 ,6 7 ,6 5. A preparation of

sulfonic anhydrides in consistently good yields would certainly be of interest in this program.

The triphenylmethoxide-sulfonyl chloride reaction would not be without analogy, various esters having been prepared by this means68 ,69,70,71, though it may be significant that benzyl esters are not among them. The reaction using potassium benzyloxide and

tosyl chloride yielded no ester -. Only half the sulfonyl chloride was consumed in the reaction and the main product (isolated in 48% yield) was dibenzyl ether. The authors suggested that the ester formed, but was as reactive as the starting chloride with respect to the benzyloxide, displacement of tosylate from carbon occurring exclusively rather than that of chloride from sulfur. The dehydration of the acid-alcohol mixture also can be sup- ported by analogous examples, sulfates being commonly prepared in this fashion, although ditrityl sulfate has been prepared, apparently, only by the reaction of trityl chloride and silver sulfate in benzene60 or liquid sulfur dioxide59. Trityl perchlorate has been successfully prepared ,y the method of removing water by aspirating airthrough a mixture of triphenylcarbinol and perchloric acid in nitrobenzene, then precipitating the product with benzene7 3 . The synthesis of trityl chloride by treatment of triphenylcarbinol with dry hydrogen chloride74 may also be cited as an example of this sort of synthesis. The common preparation of trityl chloride by allowing acetyl chloride to react with triphenylcarbinol75 leads to speculation regarding the outcome of interaction between triphenylcarbinol and acetyl tosylate. Compounds of this type have been reported 7 6 8

Results and Discussion.- The preliminary investigation of this problem showed that a promising first step was to attempt the synthesis by the procedure outlined by Tipson5 . AccordinglY, triphenylcarbinol was treated with tosyl chloride in pyridine at about -5*. Dilution with water produced a copious precipitate, which was worked up. This substance was triphenylcarbinol. The recovery of triphenylcarbinol could be explained in a num- ber of ways. No reaction at all may have occurred; esterification could have proceeded, with water hydrolyzing the ester;esterification could have been followed by ether formation, with final hydrolytic decomposition of this product.

The contingency first considered was that of ether formation.

Since demonstration of the stability of ditrityl ether to pyridinium ion would effectively dispose of this possibility, an attempt was made to synthesize this ether by one of the two published methods, Gomberg's reaction of trityl chloride with mercuric oxide7 7 . o ether could be obtained by this procedure and another attempt, by the second method (formation of ditrityl carbonate by treatment of trityl chloride with silver carbonate, followed by thermal decomposition of this ester to the desired product78 ), was being considered when it was decided that ether formation was not likely to be the main trouble. The ether preparation was postponed and eventually abandoned.

It seemed likely that there had been simply no reaction under the mild conditions of Tipson's procedure, and a duplicate experiment was carried out at the temperature of the steam bath, and __

2. another at reflux, other conditions being the same as previously.

Some crystalline material was obtained by these high-temperature procedures which had m.p. 170-1740 (uncorr.), higher than any of the starting materials. Purification yielded crystals, m.p. 172-

1750, qualitative analysis of which showed that it contained no sulfur, but that it did contain nitrogen and halogen. The elements present, coupled with the m.p., was good evidence that the product was tritylpyridinium chloride. This compound has been pre- viuosly prepared by two groups of workers7 9 ,80, with whose data the above m.p. agrees well. The shape of the crystals and the color of their pyridine solution also compared well with the data of the German workers.

The conclusion to be drawn from the formation of this compound is a little more clean cut than in the prior case of triphenylcarbinol recovery. Pyridinium salt formation occurred. Probably the desired esterification took place, and was followed by an attack on the ester by either chloride ion or pyridine. In the first of these possibilities, the trityl chloride formed could 7 9 react with pyridine, in the fashion observed by Norris and Culver to give tritylpyridinium chloride, the observed product. The attack by pyridine would lead to tritylpyridinium tosylate and precipitation of the chloride would be merely a result of its lower solubility. An alternative proposal for the mechanism in- volves the direet production of trityl chloride from tosyl chloride and triphenylcarbinol.

Another possible process is the formation of trityl chlbride 10 from triphenylcarbinol and chloride ion, catalyzed by the pyridinium ion formed in the solution. This theory is in qualitative agreement with the fact that pyridinium salt formation is, in general, an unimportant reaction with primary and secondary alcohols except those which are easily chlorinated by the Lucas

Reagent, e.g. Especially to be noted in this connection is the behavior of benzyl alcohol, a primary alcohol noted for both ease of reaction with the Lucas R-eagent and ease of pyridinium salt formation in tosylation 5. The apocamphanol case also fits, since although it is a tertiary alcohol, it is unaffected by the ordi- nary reagents which convert alcohols to the corresponding halides Apparently the quaternary salt formation is not limited to high temperatures. A solution of triphenylcarbinol and tosyl chloride in pyridine deposited crystals of this substance upon standing for several weeks.

If the first of the mechanisms is the correct one (i.e., attack on trityl tosylate by chloride ion rather than pyridine), then an attempt to synthesize trityl tosylate by reaction of triphenylcarbinol and p-toluenesulfonic anhydride offers hope, since no chloride ion need be present in such a reaction mixture.

Attack by tosylate would not affect the product (unless it were optically active). Accordingly, efforts were directed at the preparation of this anhydride. The method involving heating tosyl chloride with oxalic acid61 was selected, since a large quantity of tosyl chloride was on hand, and oxalic acid is read- ily available as the dihydrate. The choice was further influenced 11 by Shepherd's implication that this method was the best available.

In several attempts to repeat the preparation described for benzenesulfonic anhydride, no crystalline material could be isolated, but only black semisolid masses which could not be purified. Reference to the work of Miller6 2 disclosed that his efforts to duplicate the benzenesulfonic anhydride preparation gave results of similar nature. This approach was abandoned forthwith.

At this point, a reappraisal of the processes of pyridinium salt formation suggested a new approach. It is conceivable that the chloride ion attacks only the conjugate acid of the ester or alcohol, in equilibrium with the pyridinium ion in the solution. If such is the case, the use of a stronger base would displace this equilibrium in favor of the ammonium ion and de- crease the rate of chlorination, Pyridine and diethylaniline, the only two amines which have been used for this purpose, may be insufficiently basib, their dissociation constants being 1.4 x 10~9 and 3 x 10-8 (81,82), respectively. Accordingly, some experiments were carried out using triethylamine, with a constant of 5.65 x 10-4 (83), as the acid acceptor.

The first of these experiments involved the substitution of triethylamine for pyridine in the procedure of Tipson. The reaction was carried out at room temperature, and only triphenylcarbinol was obtained. After heating under reflux, the product was a dark mass which appeared to react very rapidly with the moisture in 12

the air to give a crumbly brown product from which no crystalline material could be isolated. Additionof water gave triphen-

ylcarbinol.

The addition of a large amount of water to the reaction mix-

ture to stop the reaction and precipitate the ester is an in-

tegral part of all the tosylation procedures in the literature,

However, the addition of water to reaction mixtures encountered in this investigation may have hydrolyzed any trityl compounds

present back to triphenylcarbinol. The successful preparation of ditrityl sulate by the action

of trityl chloride on silver sulfate59, 6 0 lent support to an

attempt to prepare trityl tosylate in an analogous manner. Sil- ver tosylate and trityl chloride were heated in benzene. Crys- talline material separated upon cooling, and this solid was purified, being recrystallized under anhydrous conditions, It was apparently unreacted trityl chloride. It seems likely the

the silver tosylate was not finely divided enough and soon be-

came coated with silver chloride, stopping the reaction. Further

study of this reaction seems warranted, with attention to the

facts that the silver tosylate is sensitive to light and that it

should be pulverized for this reaction.

An attempt was made to prepare trityl tosylate by removing water from a mixture of triphenylcarbinol and p-toluenesulfonic acid. Gentle heating of a small sample of a mixture of the two compounds in the absence of a solvent yielded a brilliant red melt which cooled without decolorizing. Heating to the boiling point produced a very dark green substance which had the appear- ance of the melt of triphenylcarbinol and p-toluenesulfonyl chloride, which do not give the red color upon gentle heating, however.

Gomberg used nitrobenzene as the solvent in his preparation of trityl perchlorate but p-toluenesulfonic acid monohydrate is not very soluble in nitrobenzene, either alone or when the solvent contains a large amount of triphenylcarbinol. Dry air was aspirated through a mixture of alcohol and acid in nitrobenzene. No crystalline material separated from the reaction mixture. 14

Experimental Part.- Triphenylcarbinol (student preparation) was recrystallized from 95% ethanol, yielding practically colorless

crystals, m.p. 158-161*. Complete evaporation of the solvent left a gummy orange material, probably mostly biphenyl.

Triphenylcarbinol (Eastman white label) was recrystallized from

95% ethanol. Rapid cooling of the solution gave white microcrys-

talline material, m.p. 160-160.5*. p-Toluenesulfonyl chloride (Eastman white label) was dissolved

in cold dry benzene, and after filtering to remove insoluble material, was shaken in a separatory funnel with 5% aqueous

sodium hydroxide. The layers were separated and the benzene so-

lution was dried over anhydrous potassium carbonate. Filtration and evaporation of the filtrate to a small volume gave large colorless prisms, m.p. 6 7 -94, which turned pink on standing for a few weeks. The mother liquor was used for subsequent recrystallization of other batches.

Benzene (Eastman pure) was dried by distillation until the distillate came over clear. The residue was used.

Pyridine (Eastman pure or Mallinckrodt Analytical Reagent) was dried over 97% sodium hydroxide pellets for a week, then filtered and distilled. The fraction boiling at 112-5* was used. Petroleum ether (b.p. 35-60*) was washed with concentrated sulfuric acid until the acid layer was colorless, then with water,

The material was dried over calcium chloride, filtered and distilled, b.p. 45-55*. Chloroform was purified by washing with concentrated sulfuric acid, then water. The chloroform was dried over calcium chloride and distilled. The fraction boiling near 610 was collected.

Acetyl chloride (Eastman practical) was mixed with one-tenth its volume of dimethylaniline and the resulting blue solution was slowly fractionated through a six-inch column packed with glass beads. The fraction boiling at 500 was collected.

Benzenesulfonyl chloride (Eastman practical) was distilled at the pressure of the water aspirator, b.p. 180-190* under varying pressure. The distillate was slightly yellow. A dark high-boiling residue remained.

Anhydrous oxalic acid was prepared by heating the dihydrate

(Mallinckrodt Analytical Reagent) in an oven above 100* for about forty-eight hours. It was also prepared by drawing dry air slowly through a flask charged with the dihydrate for forty- six hours. The flask was heated by means of an oil bath at 1300:

Some sublimation was noted.

Triethylamine (Sharples technical) was distilled. The fraction boiling at 8P-90* was collected.

Silver oxide was prepared by adding 40 cc. of 10% sodium hydroxide to a solution of 18.2 g. of silver nitrate in distilled water. The brown solid was filtered off and washed with water.

It was immediately utilized in the preparation of silver p-tolu- enesulfonAte.

Silver p-toluenesulfonate. The silver oxide from the above preparation was suspended in distilled water and 18.4 g. of p-toluenesulfonic acid was added. Warming of the mixture over 16

a flame produced a sudden vigorous reaction. A heavy white

granular precipitate formed, was filtered off and dried. It quickly darkened upon exposure to light.

p-Toluenesulfonic acid was prepared by boiling tosyl chloride with water until solition was complete,about three hours. Evap-

oration of the water and recrystallization from ethanol afforded

the monohydrate, m.p. 1010.

Triphenylmethyl chloride was prepared according to the method

of Organic Syntheses 82. All-glass apparatus was used, and 25 g. of triphenylcarbinol, with corresponding amounts of other reagents. The weight of the unrecrystallized product was 23 g. (78%) m.p. 110-2*0. The synthesis was repeated, using 20 g. of triphenylcarbinol and proportionate amounts of other reagents. The yield was 16.6 g.,2 (78%), m*p. 110-2*. An attempt was made to prepare ditrityl ether by the method of

Gomberg8 3. Trityl chloride (21 G.) wasdissolved in dry benzene and 24.5 g. ef mercuric oxide (Mallinckrodt, yellow, C.P.) was added. The suspension was refluxed for eight and one-half hours, and allowed to cool. The supernatant liquid was decanted into a separatory funnel and enough 0.1% hydrochloric acid was added to give clear phases after shaking. The benzene layer was dried over calcium chloride, filtered, and concentrated under reduced pressure. The orange solid mass was recrystallized from benzene but remained highly colored. A small amount of orange, partially crystalline material, m.p. 126-136*, resulted after another attempt to recrystallize. This was discarded. The ether washings

of the original crop deposited a small amount of material which was recrystallized from benzene with the aid of Norite. This

substance proved to be triphenylcarbinol, identified by its m.p. and mixed m.p. with an authentic sample.

Several attempts were made to prepare trityl tosylate. In following the procedure outlined by Tipson5 , a copious precipitate

formed upon addition of water. This solid was filtered off and washed with water until free of pyridine. Recrystallization from ether gave triphenylcarbinol, m.p. 160-160.5*. Evaporation of chloroform extracts of the filtrate gave only a small additional amount of triphenylcarbinol.

A second attempt was made, using the amounts of reagents suggested by Tipson. The mixture was heated on the steam bath for two hours. Upon cooling, some crystalline material was deposited. After filtering, the solution was diluted with water, again yielding triphenylcarbinol. The crystals which had been removed melted at 170- 1740. Recrystallization from the yellow pyridine solution gave lozenge-shaped plates, m.p. 172-175*, solidifying and remelting at 172-173*. Qualitative analysis84 showed the absence of sulfur but the presence of nitrogen and halogen. It was concluded that the compound was tritylpyridinium chloride 8 5 ,8 6. An experiment was carried out in which the reaction solution was refluxed for three hours. Concentration yielded 7.4 g. of crystals which were combined with those from the steam bath experiment.

An experiment was carried out according to Tipson's alternate 18 procedure in which 5N sulfuric acid was added to the reaction mixture after fifteen minutes to prevent pyridinium salt formation. The usual precipitate of triphenylcarbinol formed and was recrystallized from ethyl actate, m.p. 1610. Triethylamine (41 cc.) was substituted for the usual 100 cc. of pyridine in one experiment. Addition of water produced a two-phase mixture, acidification of which gave one liquid phase and a dirty white precipitate of triphenylcarbinol. Boiling the precipitated alcohol with water containing sodium hydroxide removed the acid chloride. Recrystallization of the alcohol from ether gave m.p. 1610. Refluxing a suspension of tosyl chloride (7.6 g., 0.04 moles), triphenylcarbinol (10 g., 0.0385 moles) in 41 cc. of triethylamine (these were the usual amounts used) for three hours followed by overnight cooling gave a brown semisolid mass. When an attempt was made to filter the ice-cold mixture, it became very viscous, then crumbly. The whole product was dissolved in chloroform and attempts were made to obtain crystalline material, but all such attempts failed.

3enzenesulfonic anhydride was the object of several synthetic 61 attempts. Following the procedure of Shepherd , oxalic acid

(4.5 g., 0.05 mole) and freshly distilled benzenesulfonyl chloride (17.7 g., 0.10 mole) were heated in a flask to 150-160*.

This temperature was maintained until no more sublimation appeared to be occurring. The flask was then heated briefly to 200*, attached to the water pump, and kept at 180* until volatile material stopped distilling. The mixture was by this time quite dark in color, and at the end of the prescribed heating period

was a dark oil from which no crystals separated upon cooling.

In several successive attempts to carry out this reaction,

only black oils resulted, some of which partially solidified upon cooling. Attempts to crystallize these mixtures led to isola- tion only of small amounts of oxalic acid, identified by its behavior on heating in a melting point capillary.

Similar results were obtained when Shepherd's procedure was

followed using oxalic acid (9.0 g., 0.1 mole), and p-toluenesulfonyl chloride (38.2 g., 0.2 mole). The reaction flask was

swept with dry air, the effluent fumes being strongly acidic to

moistened pHydrion paper. Attempts to recrystallize the black

solid resulting from this procedure gave only oxalic acid.

An attempt to prepare trityl tosylate was carried out by dis-

solving trityl chloride (14. Og., 0.05 mole) in 25 cc. of ben-

zene and adding silver tosylate (14.0 g., 0.05 mole). The bright

yellow suspension was refluxed seven and one-half hours and al-

lowed to cool. Some crystals formed around the walls of the flask. They appeared to be greenish in the solution, which was heated

and filtered through a filter stick constructed according to FieserF7 . The benzene was removed under reduced pressure, care being taken to exclude moisture. The brown residue was recrystal-

lized several times from carbon tetrachloride, yielding a sub-

stance of m.p. 85-90*, containing so sulfur nor nitrogen, but

containing halogen. This compound was probably impure trityl 20 chloride.

An attempt to carry out the removal of water from a mixture of triphenylcarbinol and p-toluenesulfonic acid was made. Tri- phenylcarbinol (2.6 g., 0.01 mole) and p-toluenesulfonic acid (monohydrate, Eastman white label; 1.9 g., 0.01 mole) were mixed in 78 cc. of nitrobenzene. Addition of the acid produced a bright orange color not observed with triphenylcarbinol or the acid alone in nitrobenzene. The flask was attached to the vac- uum pump as if for distillation, with a fine capillary extend- ing to the bottom of the flask. A calcium chloride tuba was placed on the inlet of the capillary and another in the line between the flask and the dry ice-acetone trap protecting the pump. Air was drawn through the mixture at a pressure of about 3 mm. for twelve hours. The weight of the second calcium chloride tube had not changed appreciably at the end of this period. The reaction mixture had become quite dark, though it remained clear. Nothing separated from the solution on standing for one week, nor in two days after dilution with benzene. 21

References

1.Bartlett and Knox, J. Am. Chem. Soc., 61, 3184 (1939). 2. Bennett and Hafez, J. Chem. Soc., 656 (1941).

3. Gilman and 3eaber, J. Am. Chem. Soc., .41 518 (1925). 4. Hahn and Walter, Ber., 54B, 1531 (1921). 5. Tipson, J. Org. Chem., 2, 235 (1944). 6. Ferns and Lapworth, J. Chem. Soc., 101, 273 (1912).

9. Medvedev amd Alekseeva, 3er., 653, 131 (1932).

10. Kenyon, Phillips, and Taylor, J. Chem. Soc., 173 (1933).

11. Kenyon, Phillips, and Shutt, J. Chem. Soc., 1663 (1935).

12. A. J. DiMilo, Unpublished work.

13. Ullman and Wenner, Ann., 12Z, 121 (1903).

14. Jaworski, Chem. Zeitung, 221 (1865).

15. Otto, Ann., 142, 100 (1867). 16. Otto, Ber., 12, 1883 (1886).

17. Otto, Ber., 19, 1832 (1886). 18. Reverdin and Crepieux, Bull. soc. chim., (3) 27, 745 (1902).

19. Ullman and Loewenthal, Ann., 1}2, 63 (1904).

20. Bamberger and Rising, Ber., 24, 241 (1901).

21. Bamberger and Rising, Ber., 4, 240 (1901).

22. Badische Anilin- und Soda-Fabrik, Ger. Pat. 162,322. 23. Reverdinand Crepieux, Bull. soc. chim., (3) 5, 1047 (1901). 24. Reverdin and Crepieux, ibid., (3) 2L, 1046 (1901).

25. Hilditch, J. Chem. Soc., 22, 238 (1911). 22

26. Wegscheider and Furcht, Monatsh., 2J, 1095 (1902).

27. Krafft and Roos, Ber., ?5, 2257 (1892).

28. Praetorius, Monatsh,, 26, 8 (1905). 29. Praetorius, ibid., 2Z, 784 (1906).

30. Billeter, Ber., JZ, 691 (1904). 31. Krafft and Roos, Ber., E, 691 (1904).

32. Schiaparelli, Gazz. chim. ital., ll, 66 (1881). 33. Georgescu, Buletinul Societatii de Sciinte din Bucuresci, 8, 673; Beilstein, Vol. XI, p. 31.

34. Sciaparelli, Gazz. chim. ital., 11, 70 (1881).

35. Georgescu, Buletinul Societatii de Sciinte din Bucuresci,

8, 668; Beilstein, Vol, XI,.p. 31. 36. Georgescu, Buletinul Societatii de Sciinte din Bucuresci, 3, 417; Beilstein, Vol. XI, p. 31.

37. Georgescu, 3uletinul Societatii de Sciinte din Bucuresci, 8, 669; Beilstein, Vol. XI. p. 31.

38. Patterson and Frew, J. Chem. Soc., 8Q, 333 (1906).

39. Shriner and Fuson, "The Systematic Identification of Organic Compounds," Wiley, Kew York, 1948, p. 141.

40. Slotta and Franke, Ber., §J, 678 (1930). 41. Georgescu, Ber., 24, 416 (1891).

42. Slotta and Franke, Ber., 0, 678 (1930), 43. Sane, Chakravarty, and Parmanick, J. Indian Chem. Soc., 2, 55 (1933). 44. Reverdin and Crepieux,,Ber.,25, 1439 (1902). 45. Sekera and Marvel, J. Am. Chem. Soc., 53, 345 (1933). 46. Ullman and Nadai, Ber., 4I, 1870 (1908), 47. Sane and Joshi, J. Chem. Soc., 125, 2481 (1924). 48. Butler, Renfrew, Cretcher, and Souther, J. Am. Chem. Soc.,

a, 227 (1937).

50. Ohle, Euler, and Lichtenstein, Ber., 62, 2885 (1929). 51. Hess and Pfleger, Ann., 507, 48 (1933). 52. Hess and Stenzel, Ber., 68, 981 (1935). 53. Swain, Esteve, and Jones, J. Am. Chem. Soc., 11, 965 (1949). 54. Org. Syntheses, Coll. Vol. I, 145 (1941). 55. Swain, J. Am. Chem. Soc., 70, 1119 (1948). 56. Izmail'skii and Popov, J. Gen. Chem. (U.S.S.R.), 8, 965 (1938); C.A. 21, 1263 (1939). 57. Demeny, Rec. trav. chim., 50, 60 (1931). 58. Gomberg and Cone, Ann., 170, 194 (1909). 59. Gomberg and Cone, Ber., a. 3543 (1904). 60. Gomberg, Ber., 40, 1849 (1907). 61. Shepherd, J. Org. Chem., 12, 275 (1947). 62. Miller, Ph. D. Thesis, Mass. Inst. of Tech., 1949. 63. Meyer and Schlegl, Monatsh., 34, 561 (1913). 64. Noller and Hearst, J. Am. Chem. Soc., 70, 3955 (1948).

65. Billeter, Ber., 38, 2016 (1905). 66. Abrahall, J. Chem. Soc., 49, 692 (1886). 67. Hubner, Ann., 223, 244 (1884).

68. Schieler and Otto, Ber., 2 , 1638 (1876). 24

69. Otto, Ber., 19, 1832 (1886).

70. Hubner, Ann., 223, 235 (1884.)

71. Bourcet, Bull. soc. chim., (4) _1l' 363 (1912). 73. Gomberg and Cona, Ann., 2[_0, 194 (19090.

74. Gomberg, 3er., 0, 2401 (1902).

75. Org. Syntheses,23, 100 (1943).

76. 3aroni, Atti accad. naz. Lincei, (6) 17, 1081 (1933); Chem. Zentr., I, 1183 (1934).

77. Gomberg, J. Am. Chem. Soc., 2, 205 (1913). 78. Halford, J. Am. Chem. Soc., 31, 2158 (1929).

79. Norris and Culver, Am. Chem. J., 29 134 (1903). 80. von Meyer and Fischer, J. prakt. Chem., 82, 523 (1910). 81. Lange, "Handbook of Chemistry," 7th Ed., Handbook Publish-

ing Co., Sandusky, 1949, p. 1410.

82. Hall and Sprinkle, J. Am. Chem. Soc., 4, 3469 (1932).

83. Lange,"Handbook", p. 1410.

84. Shriner and Fuson, "Identification of Organic Compounds, " p. 52.

85. Norris and Culver, Am. Chem. J., 2, 134 (1903), report

"large pink crystals," m.p. 167-167.5*. 86. von Meyer and Fischer, J. prakt. Chem., 82, 523 (1910), report colorless prisms, m.p. 171*; the solution of their

compound in pyridine was bright yellow.

87. Fieser,"Experiments in Organic Chemistry", 2nd Ed., Heath,

Boston, 1941, p. 333.