Journal of the Chemical Society 1877./II. [antikvár]

PAPERS READ BEFORE THE CHEMICAL SOCIETY. X.—Transformation of Aurin into Bosaniline. By R. S. Dale, B.A., and 0. Schoelemmer, F.R.S. In our paper on aurin (this Journal, 1873, 434) we shortly mentioned a red colouring matter called peonin or red aurin, which is formed by the action of ammonia on aurin. This compound contains nitrogen, and yields, when heated with solid caustic potash a distillate containing aniline. When red aurin is heated with alcoholic ammonia for several days to 150°, the red colour of the solution disappears, and a yellow liquid is obtained, which on the addition of water deposits a white crystalline precipitate. This body possesses all the characteristic properties of rosaniline; it dissolves in acetic acid with a splendid crimson colour, and yields with strong hydrochloric acid a dark yellow solution, which on the addition of water becomes red. It dyes wool and silk the same shade, and under exactly the same conditions as pure magenta does, and fixes on cotton mordanted with antimony tannate like this colour. The formation of this colourino: matter from aurin is explained by the equation— CO„Hu03 -f 3NH3 = C OH„N3 t- 3H2O. According to Hofmann, however, rosaniline has the composition CsoHigNa, and Caro and Wanklyn converted it (1866), by means of the diazo-reaction, into rosolic acid, which, as Caro and Graebehave shown (1873), has the formula CooHieOa, while aurin has undoubtedly the formula C20H14O3. A careful investigation of our base and its salts will clear up these points ; we will only here remark that, in analyses of organic colouring matters, the percentage of hydrogen is often found too high. An example of this kind is offered by Schunck's classical research on alizarin, which he carefully analysed, and found that the results agree best with the formula CuHioOa, instead of C14HBO4. In comparing the absorption-spectrum of the hydrochloride of our base with that of pure rosaniline hydrochloride, we found them quite identical. We have transformed our rosaniline, not only into Hofmann's violet and aniline-blue, but also into aniJine-green, obtainiag at the same time the violet, which is always produced in the formation of the green. vol. xxxii. k