Synthesis of 3(2-haloethyl)aryltriazenes and study of their reactions in aqueous solution

• Published in: Canadian journal of chemistry Vol. 59; no. 9; pp. 1347 - 1356
• Main Authors: Lown, J. William, Singh, Ranjit
• Format: Journal Article
• Language: English
• Published: Ottawa, Canada NRC Research Press 01.05.1981
• ISSN: 0008-4042; 1480-3291
• DOI: 10.1139/v81-198

Several 1-aryl-3-(2-haloethyl)triazenes have been synthesized and characterized spectroscopically as well as by their esterification of 3,5-dinitrobenzoic acid. Their rates of decomposition in aqueous media at pH7 were determined polarographically employing the electrochemically active triazene moiety. In two selected cases the rates of decomposition increase markedly with lowered pH in the range 9.3 to 4.65. The products of aqueous decomposition, both volatile and involatile, were identified and quantitated by gc and gc-ms. Discrimination between alternative decomposition pathways was possible by the preparation and use of selectively deuterated triazenes. The data are consistent with initial protonation of the triazene and generation therefrom of a 2-haloethyl cation (or its kinetic equivalent) which is subject to rearrangements detected by deuterium scrambling. A second competing pathway involves cyclization of the triazene to a 1-aryl-1,2,3-triazoline intermediate which is then subject to nucleophilic opening at two sites with attendant loss of nitrogen. The effects of structural changes in the triazenes on their modes of decomposition and generation of electrophiles should assist in the interpretation of their antitumor effects.