Kastle also found that by dissolving the mixed chlorides in alcohol in the cold, and allowing the solution to evaporate, there separated after a time, crystals of the chloride of the acid etherial salt of paranitroorthosulphobenzoic acid whose formation and composition are represented in equation I.
This same product was sought for when pure symmetrical chloride was employed, but without success. In every case, crystals of unchanged chloride separated, or else it was found that it had been completely converted into the acid etherial salt. In another trial cold water was carefully added in small portions, since Kastle found that such treatment facilitated the separation of the substance; the chloride alone appeared. Still other attempts were made to obtain the substance by adding a large amount of water to the solution of the chloride in alcohol, after it had stood for some time. In this way, quite a precipitate was thrown down, and this was filtered off and crystallized from ether. It always proved to be the symmetrical chloride, and none of the other substance was obtained.
Karslake[16] in working with the symmetrical chloride of orthosulphobenzoic acid, was unable to isolate the analogous compound, although from the mixed chlorides, by the action of alcohols, Remsen and Dohme[17] had obtained chloro-etherial salts.
In as much as the pure symmetrical chloride is relatively stable in cold alcohol (it can be crystallized from warm alcohol with very little loss), it is possible that it is more stable than the chloro etherial salt, and that in consequence the latter, when formed, yields more readily to the further action of alcohol than does the unacted on chloride. Hence when the action begins, it at once proceeds to the limit. The fact that the symmetrical chloride is rather sparingly soluble in cold alcohol, making the use of concentrated solutions impossible, may also be a factor in the case. Whatever may be the cause, this substance could not be obtained under any conditions that were devised.
Having in my possession a very small specimen of crystallized unsymmetrical chloride, it was submitted to the action of ethyl alcohol, under as nearly as possible the conditions employed by Kastle. Crystals of a colorless substance were obtained, which in every respect agreed with Kastle’s description of the chloride of the acid ethyl etherial salt of paranitroorthosulphobenzoic acid. Crystallized from ether they melted at 68°.
The conditions employed by Kastle in preparing the chloride would undoubtedly lead to a relatively large proportion of unsymmetrical chloride, and it is to this chloride that the formation of the chloro etherial salt is apparently due.
VII. The Action of Phenols upon the Symmetrical Chloride
of Paranitroorthosulphobenzoic Acid.
Remsen and Saunders[18] in their investigation of the chlorides of orthosulphobenzoic acid, studied the action of phenol upon these substances, and from both the symmetrical chloride and the mixed chlorides, they obtained a normal diphenyl ether together with a red substance which was not further studied. It was formed in small quantity and was probably the corresponding sulphonphthalein. Later McKee[19] obtained these same substances from both the symmetrical and the unsymmetrical chlorides. R. Meyer[20] obtained analogous substances by the action of various phenols upon phthalyl chloride. It seemed probable, therefore, that the chlorides of paranitroorthosulphobenzoic acid would yield similar derivatives, and a study was accordingly made of the reaction of the symmetrical chloride with a series of phenols. The products in some instances were exceedingly difficult to deal with, possessing properties that made it impossible to prepare them for analysis, but even in such cases there could be little doubt as to the general nature of the reactions which had occurred.
1.The Action of Phenol upon the Symmetrical Chloride of Paranitroorthosulphobenzoic Acid.
A portion of the symmetrical chloride was brought together with somewhat more than double the molecular amount of phenol. The mixture was placed in a good-sized test-tube and the temperature gradually raised by means of a sulphuric acid bath.