Arylazoglyoxalinecarboxlic acids / by Robert George Fargher.

  • Fargher, Robert George.
Date:
[1921?]
Catalogue details

Licence: In copyright

Credit: Arylazoglyoxalinecarboxlic acids / by Robert George Fargher. Source: Wellcome Collection.

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    nitrite and added to an ice-cold solution of 9'23 grams of 2-phenyl- glyoxaline-4:5-dicarboxylic acid in 400 c.c. of water containing 67‘2 grams of sodium carbonate crystals, when gradual separation of a deep orange precipitate took place. After five hours, this was collected. It consisted of the sodium salt of At-g>-bromobenzene- azo-2-phenylglyoxaline-5-carboxylic acid admixed with that of the unchanged acid. Separation was readily effected by crystallisation from water containing a little sodium carbonate, the former dis¬ solving very sparingly in cold water. The corresponding acid was readily obtained on acidification, and was further purified by crystallisation from alcohol. 4:-ip-Bromobenzeneazo-2-phenylglyoxaline-5-carboxylic acid is in¬ soluble in water and only very sparingly so in alcohol, from which it separates in glistening, red needles, which darken on heating above 160° and effervesce and decompose at 210° (corr.). It dis¬ solves in sulphuric acid, with the production of an eosin-red color¬ ation (Found: C = 516; H = 3'3; N = 14-8. C16Hn02N4Br requires C = 516; 11 = 3-0; N = 15*l per cent.). The sodium, salt separates from water as a felted mass of orange needles containing 3H20 (Found: loss at 60° in a vacuum = 12*0. C16H10O2N4BrNa,3IT2O requires H20 = 11'8 per cent. In dried material, Na = 5‘6. C16H10O2N4BrNa requires Na = 5-8 per cent.). The same product was obtained when 2-phenylglyoxaline-4-carb- oxylic acid wras substituted for the dicarboxylic acid. Reduction.— Four grams of the acid were triturated with 25 c.c. of concentrated hydrochloric acid, and gradually treated with 14 c.c. of stannous chloride solution,* the trituration being con¬ tinued until the completion of the experiment. Evolution of carbon dioxide quickly became evident. The insoluble stanni- chloride was collected, freed from tin by means of hydrogen sulphide, and the resulting solution evaporated to low bulk under diminished pressure, when separation of a crystalline hydrochloride took place. This was purified by recrystallisation from water con¬ taining a little hydrochloric acid, and formed colourless needles melting at 255°' (corr.). This was fully identified by analysis (Found: C=45T; H = 4‘0; N = 13-6. Calo.: C = 44-8; 11 = 3-8; N = 13-8 per cent.), by the preparation of the triacetyl derivative (Found: N = 12*2. Calc. : N = 12*3 per cent.), and by its reactions (T., 1919, 115, 257) as 5-amino-4-(2/-amiuo-5/-bromophenyl)-2- phenylglyoxaline (T., 1920, 117, 671). In an attempt to characterise and compare the two products more completely, it was found that sodium acetate yielded a grey precipi¬ tate, which redissolved on adding a little acetic acid and warming, * Prepared as described in the earlier communications.