The abnormal behaviour of glyoxaline-carboxlic esters and anilides towards diazonium salts / by Robert George Fargher and Frank Lee Pyman.

  • Fargher, Robert George.
Date:
1919.]
Catalogue details

Licence: Public Domain Mark

Credit: The abnormal behaviour of glyoxaline-carboxlic esters and anilides towards diazonium salts / by Robert George Fargher and Frank Lee Pyman. Source: Wellcome Collection.

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    LXXXVII. — The Ahriormal Behaviour of Glyoxaline- carboxylic Esters and Anilides towards Diazonium Salts. By Robert George Fargher and Frank Lee Pyman. In a recent paper (this vol., p. 217), we put forward evidence show¬ ing that glyoxalines are only capable of coupling with diazonium salts when they contain a free imino-group and also a hydrogen atom or some other displaceable group, such as the carboxyl group, in one of the 2-, 4-, or 5-positions. Numerous derivatives of glyoxaline, in which these conditions are fulfilled, have been shown to couple with sodium diazobenzene-^7-sulphonate in aqueous sodium carbonate, but an exceptional behaviour is shown by the esters of 5-methylglyoxaline-4-carboxylic acid (Gerngross, Ber., 1912, 45, 513) and the esters of glyoxaline-4-carboxylic acid (Pyman, T., 1916, 109, 186). These give a negative result, whereas the corre¬ sponding acids behave normally, giving deep red solutions with the reagent. With the object of finding some clue to this abnormality, we have examined the behaviour of a number of carboxylic acids containing the glyoxaline nucleus and their esters towards sodium diazobenzene- 2?-sulphonate in aqueous sodium carbonate. All the acids examined gave a positive result, and so also did the esters of those acids, such as glyoxalineacetic acid, in which the carbonyl group is separated from the glyoxaline nucleus by a chain of one or more carbon atoms. The esters of the 2-alkylglyoxaline-4-carboxylic acids, however, like those of glyoxaline-4-carboxylic acid and 5-methylglyoxaline-4- carboxylic acid, gave a negative result, and so also did the anilides of glyoxaline-4-carboxylic acid and its 2-alkyl derivatives. In order to ensure that the difference in behaviour was not due to the particular conditions selected for the test, the action of benzene- diazonium chloride and p-nitrobenzenediazonium chloride on glyoxaline-4-carboxylic acid and ethyl glyoxaline-4-carboxylate was examined. In the presence of hydrochloric acid or acetic acid, neither of the derivatives coupled, whilst in the presence of sodium carbonate or sodium hydroxide the acid coupled but the ester did not. The abnormality is thus seen to be connected with the direct attachment of the carboxyalkyl or carboxyanilide group to the glyoxaline nucleus, and would seem to be due to the mutual influence of the imino- and carbonyl groups.