Pyrazolines X. Kinetics for the pyrolysis of some deuterated 1-pyrazolines in solution

Abstract

The kinetics and product distribution have been measured for the pyrolysis of 3-methyl-3-carbo-methoxy-1-pyrazoline (1) and its 4,4-d2 and 5,5-d2 analogues in tetralin, n-butyl phthalate, nitrobenzene, and formamide. The isotope effect kH/kD for 1-5,5-d2 of 1.22 and for 1-4,4-d2 of 1.36 is consistent with a mechanism involving migration of the C-4 hydrogen concerted with loss of nitrogen.