ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Kinetics of cyclization of N-substituted 1-(2-nitrophenyl)-guanidines and mechanism of the cyclization reactions

P. Pazdera and M. Potáček

Department of Organic Chemistry, Faculty of Natural Sciences, J. E. Purkyně University, CS-611 37 Brno

Abstract: Kinetic measurements of cyclization of 3-ethyl-l-(2-nitrophenyl)guanidine and 2-phenyl-l-(2-nitrophenyl)guanidine to 3-ethyl- and 3-phenylamino-l,2,4-benzotriazine 1-oxide were carried out in dependence on pH of the reaction medium by spectrophotometry. The rate constants k_I calculated for the unimolecular order of the reac­tion were proved to be linearly dependent on pH of the medium. Also the rate constants k_IIfor the bimolecular order of the reaction were calculated. From the results of this kinetic study and the published experimental findings about the properties of 2-nitrophenylguanidines and their cycliza­tion to substituted 3-amino-l,2,4-benzotriazine 1-oxides the mechanism of this base-catalyzed reaction was proposed.

Full paper in Portable Document Format: 442a241.pdf

Chemical Papers 44 (2) 241–248 (1990)