1:3-Benzodiazolearsinic acids and their reduction products : by Robert Reginald Baxter and Robert George Fargher.

  • Baxter, Robert Reginald.
Date:
1919.]
Catalogue details

Licence: Public Domain Mark

Credit: 1:3-Benzodiazolearsinic acids and their reduction products : by Robert Reginald Baxter and Robert George Fargher. Source: Wellcome Collection.

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    5 : 5f-A.rseno-1 : 3 : V: 3'-benzodiazole (VIII). A solution of 5 grams of 1 :3-benzodiazole-5-arsinic acid in 100 c.c. of water containing 1*2 grams of sodium hydroxide was treated with 50 grams of sodium hyposulphite and 11'5 grams of magnesium chloride dissolved in 300 c.c. of water, and the mixture heated, with stirring, at 60° for two hours in an atmosphere of carbon dioxide, by which time the precipitation of the yellow arsenobenzene was complete. After cooling, the product was collected, well washed with water, suspended in 90 c.c. of water, dissolved by the addition of sufficient hydrochloric acid to form the dihydrochloride, filtered from traces of undissolved matter, and precipitated by pouring into an equal volume of concentrated hydrochloric acid. The hydrochloride was collected, well washed with alcohol and ether, and dried in a vacuum over sulphuric acid. The yield amounted to 39 grams. 5 : b'-Arseno-1 : 3 :17: V-benzodiazole is obtained as a bright yellow powder practically insoluble in water or the usual organic solvents, sparingly, if at all, soluble in methyl alcohol containing hydro¬ chloric acid, but fairly readily so in 50 per cent, acetic acid. The dihydrochloride forms a pale yellow powder soluble in water, very sparingly so in methyl alcohol or ethyl alcohol, and quite insoluble in acetone or ether. The aqueous solution reacts acid to litmus, but neutral to methyl-orange. After drying in a vacuum over¬ night, it retains solvent equivalent to two molecules of water. Found: N = ll*3; As = 30-2; Cl = 13*8. C14H10N4As2,5HC1,2H2O (493T) requires N = ll*4; As = 30'4; Cl —14‘4 per cent. 3 :4:-Diacetylaminophenylarsinic Acid and 2-Methyl-1 :3-benzo- diazole-5-arsinic Acid (VI). Experiments in which diaminophenylarsinic acid was heated with glacial acetic acid, with acetic anhydride, with acetyl chloride and pyridine, or with acetic anhydride in the presence of a trace of sulphuric acid, were unsuccessful, owing to the considerable amount of decomposition which occurred. It was found, however, that if the acid, dissolved in methyl alcohol, was treated with a mixture of acetic acid and acetic anhydride, and the methyl alcohol then removed as completely as possible by distillation on the water-bath, the resulting solution, after heating to active boiling for four hours, gave an excellent yield of a product, which, from its composition, proved to be the diacetyl derivative of diaminophenylarsinic acid. 3: 4i-J)iacetylaminophenylarsinic acid crystallises from water, in
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