Arylazoglyoxalinecarboxylic acids / by Robert George Fargher.

Fargher, Robert George.

Date:: 1921.]

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

2/8 page 159

$tion, one of the carboxylic acid groups being displaced by the arylazo-group The same product, namely, 4:--p-bromobenzeneazo- 2-plienylglyoxaline-b-carboxylic acid, is obtained when the mono- carboxylic acid is substituted for the dicarboxylic acid in the reaction. Similar results are obtained with 2-methylglyoxaline-4:5-dicarb- oxylic acid, although in this case the reaction appears to proceed rather more slowly. It had been anticipated that, as the possibilities of benzidine formation had been very largely excluded, the reduction of these compounds with cold stannous chloride solution would lead to the corresponding amino-acids, and that, although subsequent trans¬ formation into the glyoxalone might be anticipated in the case of the 2-methyl derivative, unless, indeed, the presence of the adjacent carboxylic grouping proved inhibitive, in that of the 2-phenyl derivative stability might reasonably be anticipated, as it had already been ascertained that the reduction of 4-p-bromobenzene- azo-2-phenylglyoxaline led to a substance which almost certainly possessed the constitution 5-amino-4-(2/-amino-5/-bromophenyl)-2- phenylgly oxaline. This has, however, proved not to be the case. The reaction follows a somewhat novel and unexpected course, the second carb¬ oxylic grouping being eliminated during the process of benzidine formation, the acids yielding the same products as the correspond¬ ing non-carboxylated glyoxalines. In view of these results, it appeared to be of interest to examine the reduction of %p-bromobenzencazoglyoxalinc-^\b-dicarboxylic acid under similar conditions. The tendency towards benzidine formation is here sufficiently less pronounced to permit of the isolation as main product of ‘l-p-bromobenzenehydrazoglyoxaline- 4 dicarboxylic acid. It has already been shown that glyoxalinedicarboxylic acid and its 2-methyl homologue are not acted on by a warm mixture of nitric and sulphuric acids (T., 1919, 115, 217). 2-Phenylgly- oxaline-4 :5-dicarboxylic acid reacts under these conditions, but as the composition of the product indicated that substitution had taken place only in the benzene nucleus, its further examination has been omitted. Experimental. 4:-'p-Bromobenzeneazo-2-phenylglyoxaline-5-carboxylic Acid. A solution of 6*8 grams of p-bromoaniline in 130 c.c. of 10 per cent, hydrochloric acid was diazotised with 2'88 grams of sodium$

Arylazoglyoxalinecarboxylic acids / by Robert George Fargher.

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