The affinity constants of amphoteric electrolytes. I.—Methyl derivatives of para-aminobenzoic acid and of glycine

Abstract
The following investigation was undertaken in order to determine the influence on the basic and acidic constants of successive introductions of a methyl group into an amino-acid, including the effect of changing the acid into the corresponding methyl ester. Two series of compounds were investigated, namely, the methyl derivatives of p-aminobenzoic acid and of glycine. Constants for p-aminobenzoic acid, glycine, and some of its methyl derivatives had already been determined by Winkelblech. Methods. Whenever practicable the basic constant kb was determined by means of the catalysis of methyl acetate, using the comparison method of Walker and Wood. The end point was determined in a separate experiment with decinormal hydrochloric acid; and it was found that the same result was obtained whether or not the bottle containing the reaction mixture had been opened to admit of intermediate readings being taken. In every case 1 c.c. at a time was withdrawn and titrated with N/20 caustic soda, which had been prepared from sodium and conductivity water; and unless otherwise stated, phenolphthalein was used as indicator.

This publication has 0 references indexed in Scilit: