Very low pressure reactor. A new technique for measuring rates and equilibriums of radical-molecule reactions at low temperature. Heat of formation of the methyl radical

Abstract

We wish to report here a new method for measuring rate constants and equilibrium constants of molecule-radical reactions near ambient temperatures. The method, using a very low pressure reactor (VLPR) is a variation of our very low pressure pyrolysis technique (VLPP) which has been described in detail elsewhere. VLPP has been restricted to high temperatures (>700 K) because of the necessity of generating radicals rapidly (< 10^(-1) s) via thermal pyrolysis. It also suffers from the difficulty of requiring extensive correction for radical reactions on the reactor walls. We have solved the first problem of generating radicals at low temperatures by dissociating diatomics in a microwave discharge and diffusing them into the reactor. The atoms as generated will react with suitably chosen substitutes to form radicals. The surface reactivity problem has been solved by using a fluorocarbon coating on our reactor walls which seems to be totally inert (< 10^5 collisions) to reactive atoms or radical. We are engaged in an extensive study of radical reactions using these technique. The present report is concerned with its application to equilibria.