The photochemistry of cyclobutyl methyl ketone. Part 1.—Room-temperature results and the general mechanism

Abstract

Gaseous mixtures of cyclobutyl methyl ketone (CMK) diluted in argon have been photolysed at room temperature at a variety of pressures and wavelengths in the range 325–193 nm. Both steady-state and pulsed (laser) photolyses were carried out. Conversions were limited to ca. 5% and a reasonably complete product analysis achieved (mass balance and product ratio checks). The results support the occurrence of the main primary processes: [graphic omitted]. These are followed by a set of radical–radical reactions involving methyl, acetyl and cyclobutyl radicals. The Norrish type I processes (1a) and (1b) are dominant at long wavelengths but decline at shorter wavelengths. The molecular pathway (2a) shows the converse wavelength dependence. There is some evidence for two-photon processes in the laser photolyses. A number of radical–radical rate constant ratios have been obtained.