The identification of amino-acids by means of 3:5-dinitrobenzoyl chloride

Abstract

3:5-Dini-trobenzoyl chloride is recommended as a reagent for the rapid identification of many amino-acids, crystalline derivatives usually being obtained in good yield. The condensation is almost instantaneous in alkaline soln. The acidic amino-acids appear to be less reactive towards this reagent, and a separation of glycine and other monoamino carboxylic acids from aspartic acid is based on this fact. The 3:5-dinitrobenzoyl derivatives of certain amino-acids are precipitated from alkaline soln. by dilute acetic acid, others only by dilute HC1. In this way glycine and leucine have been separated. Guanidine gives a good yield of di(3:5 dinitrobenzoyl) guanidine insoluble in alkali. Thiolacetic acid and cysteine give S-derivatives which are not suitable for identification purposes.