The detection of some halogenated phenols and nitrophenols in thin-layer chromatography by means of bromine : II. The detection of small quantities of phenols and dicyclohexylurea derivatives in samples of activated phthaloyl--amino acid esters

Abstract

A method is described for the detection of halogeno- and nitrophenols in submicrogram quantities.

Small quantities of these phenols were present as impurities in samples of activated phthaloyl--amino acid esters. The esters and phenols were separated on thin layers of silica gel in nonaqueous developing solvent systems and visualized by exposure of the plates to bromine vapour and subsequent spraying with an aqueous solution of potassium iodide.

Other impurities, dicyclohexylurea and N-acyldicyclohexylureas, were detectable by the same or by analogous procedures.