The thermal decomposition of 1-(2′-cyano-2′-propoxy)-4-oxo-2,2,6,6-tetramethylpiperidine

Abstract

The thermal decomposition of 1-(2-cyano-2′-propoxy)-4-oxo-2,2,6,6-tetramethylpiperidine in solution has been studied as a function of solvent, temperature, and the presence of radical scavengers. In the absence of a scavenger, decomposition produces a hydroxylamine and methacrylonitrile, whereas in the presence of a scavenger such as oxygen, a nitroxide and 2-cyano-2-propyl radicals result. Decomposition in the presence of a scavenger is ∼50 times more rapid than decomposition in its absence. By using various free radical scavengers, scission of the NO—C bond is confirmed, that is the reverse of the normal nitroxide–alkyl radical reaction. Increasing solvent polarity causes a marked decrease in thermal stability, both in the presence or absence of radical traps. The importance of the thermal decomposition reactions in the interpretation of nitroxide scavenging of radicals is discussed.