TERMINATION RATES BY TIME-RESOLVED ESR. THE N-HYDROPYRIDINYL RADICAL IN SOLUTION AND THE INFLUENCE OF NON-UNIFORM RADICAL CONCENTRATION ON THE APPARENT RATE CONSTANT.

Article abstract of DOI:10.1002/bbpc.19840880509

The rate constants (2k) for the second-order self-termination reaction of the N-hydropyridinyl radical have been measured by time-resolved ESR during intermittent UV photolysis of pyridine in various solvents containing propanol(-2). The frequency factor and the activation energy are (1. 8 plus or minus 0. 4) multiplied by 10**1**0 M** minus **1 s** minus **1 and (10. 7 plus or minus 0. 4)kJ multiplied by mol** minus **1, respectively, in propanol(-2)/acetone (1:1 by volume) as obtained from the Arrhenius plot of 2k in the temperature range between 293 and 230 K. A model is presented for the correction of the influence of non-uniform radical concentration on apparent values of second-order rate constants as determined by time-resolved ESR during intermittent photolysis.