Evaluation of the effect of the furazane fragment on the NH acidity of 4- and 5-picrylaminobenzofurazanes in DMF and DMSO

Abstract

The products of the reactions of picryl chloride with isomeric aminobenzofurazanes in DMF and DMSO were studied by means of nonaquoeus potentiometric titration. The effect of the position of the furazane fragment in 4- and 5-picrylaminobenzofurazanes on the NH acidity is considered. The electron-acceptor properties of the furazane fragment were evaluated via inclusion of the resulting data into the pK a-σ correlation for 2,4,6-trinitrodiphenylamines. On this basis, conventional Hammett σ constants were calculated for the furazane fragment located in the immediate vicinity of the N-H center and one position distant from it. © 2005 Pleiades Publishing, Inc.