A S I L I S E AKD 34ETHYL CHLORIDE* BY WILDER D. BASCROFT ASD BURTON C. BELDEX
One finds the statement in reference books of organic chemistry’ that methyl chloride acts upon boiling or hot aniline to produce a mixture of the hydrochlorides of methyl aniline and dimethyl aniline, the statement being based upon the work by A. W. Hofmann’ in which he investigated the action of methyl chloride] bromide, and iodide upon aniline. S o claim has ever been made, so far as the authors are aware, that aniline and methyl chloride will react with each other at room temperature. I n the course of Phase Rule investigations in this laboratory, using the methods and apparatus of Bancroft and B a r r ~ e t t we , ~ had occasion to investigate the action of methyl chloride gas upon liquid aniline and we observed that there is a slow interaction bet,ween the two even at 2 j”C. X ten-gram sample of aniline, for instance, in the presence of an atmosphere’s pressure of methyl chloride, showed in the course of six hours the formation of a perceptible amount of a solid phase which had the appearance of a reddish-purple slush. Methyl chloride continued to be taken up slowly, so that at the end of 40 days 887, of one equivalent of the gas had been consumed, and at the end of 1 0 2 days the reaction apparently had come to a stop with 99. j% of one equivalent of methyl chloride bound by the aniline. At this point 5.398 milligrams of methyl chloride were held by the aniline, which represents j40 milligrams per gram aniline. The calculated amount is 543 milligrams of the gas per gram aniline, assuming the combination to be that of one mole of methyl chloride with one mole of aniline. At the completion of the reaction the content of the reaction flask was a solid mass of magenta color. This reaction, naturally enough, proceeds much more rapidly at elevated temperatures; a sample of 1.97 grams aniline, for instance] held at I O ~ O C . , combined with 88’3 of one equivalent of methyl chloride in the course of forty-eight hours. The resulting solid had the same appearance as in the previous experiment carried on at room temperature] except that a little solid sublimed into the upper regions of the reaction flask, forming white, needle-like crystals. The increased speed of the reaction was due in part to the smaller aniline sample used, giving a relatively larger surface, but the principal factor was the increased temperature. Aniline is soluble in ether; methyl aniline hydrochloride is insoluble. A sample of 1.45 grams aniline, treated for a convenient length of time (but *This work is done under the programme now being carried out at Cornell University and supported in part by a grant from the Heckscher Foundation for the Advancement of research established by August Heckscher at Cornell University. Beilstein: “Handbuch der organischen Chernie,” 12, j 2 ( I r i j i ) . * Ber., 10, 594 ( 1 8 i i ) . Bancroft and Barnett: J. Phys. Chem., 34, 449 (1930); Belden: J. Phys. Chem., 35, 2164 (1931).
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ANILINE AND METHYL CHLORIDE
3091
not, until the reaction was complete) with methyl chloride, was extracted with ether to remove the unconverted aniline. The resulting solid material p-as readily soluble in water and gave instantly a silver chloride precipitate when dropped into silver nitrate solution, which showed the solid to be a hydrochloride. Methyl chloride gas, bubbled through silver nitrate solution, clouds the silver nitrate little, if any, in the course of an hour. The purple appearance of this solid might suggest a considerable conversion of the original aniline into a colored substance. The purple material proved to be insoluble in ether, and s'oluble in water and ethyl alcohol. The hydrochloride of the previous paragraph was dissolved in water and then neutralized with 5 / 2 0 sodium hydroxide, using brom thymol blue indicator whose color change could be seen even in the presence of the magenta coloration. The resulting methyl aniline (and perhaps dimethyl aniline) was extracted with ether, leaving in the mater layer the purple coloration and the sodium chloride resulting from the neutralization. On evaporation of this solution on a steam bath, the color intensified slightly and proceeded to disappear, leaving at dryness sodium chloride crystals and almost nothing else. We conclude from this that during the reaction of aniline with methyl chloride a small amount of an aniline dye of intense color is formed and that there is not a considerable conversion into this colored substance. We were interested further to learn the nature of the reaction, if any, between methyl chloride and biuret. We found that methyl chloride and biuret appear not to react at all with each other in this same apparatus at temperatures up to IOO'C. We tried passing the gas over powdered biuret in a U-tube at temperatures up to the decomposition point (190°C.) of the solid; the product of the reaction of biuret with methyl chloride should be one or more molecules of HC1, which could be readily identified by passing the gas through silver nitrate solution. Above 14o'C. we obtained a noticeable evolution of HCL gas. However, the weight of the solid decreased during the process, which is not what should happen if biuret is being converted into methyl biuret. We surmised that the one molecule of water with which biuret crystallizes had not been removed completely in drying the solid. After drying the solid more carefully to a constant weight, we were unable to obtain evidence of any reaction with methyl chloride up to 18ooC., at which temperature the biuret commenced to sublime out of the U-tube. The conclusions to be drawn from this paper are these: I. Methyl chloride reacts with aniline slowly at room temperature to form a magenta-colored solid. The solid is principally methyl aniline hydrochloride with a small amount of intense dye. 2. The same reaction occurs much more rapidly a t 10j"C. 3 . Methyl chloride does not react with dry biuret at any point below 180'C. The authors are indebted to the Roessler and Hasslacher Chemical Company for methyl chloride (Arctic Gas). Cornell Cniversity
