FREE RADICAL MECHANISMS FOR INHIBITED ORGANIC DECOMPOSITIONS

Abstract

It is suggested that organic decompositions that are fully inhibited by substances such as nitric oxide and propylene proceed not by molecular mechanisms, but by special types of free radical mechanisms in which the inhibitor is involved in both initiation and termination. In the case of nitric oxide inhibition, initiation is considered to be by the abstraction of a hydrogen atom by NO, while termination involves reaction between the most plentiful chain carrier and either HNO or NO, depending upon whether or not H is a chain carrier. Specific mechanisms are proposed for the decompositions of paraffins, ethers, and aldehydes, when inhibited by nitric oxide, and the resulting rate equations are shown to be consistent with the behavior observed experimentally. It is shown for the ethane decomposition that the same limiting rate is obtained for any inhibitor that can become involved in the same type of mechanism.