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

Kinetic-study of the cyclization of 2-(3-phenylthioureido)benzonitrile to 3-phenyl-4-imino-1,2,3,4-tetrahydroquinazoline-2-thione

P. Pazdera and J. Pichler

Department of Organic Chemistry, Faculty of Natural Science., Masaryk University, CS-61137 Brno

Abstract: The rate of the cyclization of 2-(3-phenylthioureido)benzonitrile to 3-phenyl-4-imino-1,2,3,4-tetrahydroquinazoline-2-thione in acetonitrile in dependence on the catalyst concentration (water or methanol) and temperature was studied. The cyclization reaction was found to be irreversible following the kinetic equation of the first order with respect to the starting concentration of the substrate and the catalyst. From the temperature dependence of the rate of the cyclization and the Arrhenius equation values of the activation energy and the frequency factor were calculated. From the Eyring equation values of the activation enthalpy and entropy were calculated. On the basis of the experimental results the probable mechanism of reaction is discussed.

Full paper in Portable Document Format: 454a517.pdf

Chemical Papers 45 (4) 517–525 (1991)