LIQUID-CRYSTALLINE SOLVENTS AS MECHANISTIC PROBES. 23. NORRISH II REACTIONS OF 2- AND SYM-ALKANONES IN THE ISOTROPIC, SMECTIC B, AND CRYSTALLINE PHASES OF n-BUTYL STEARATE.

Article abstract of DOI:10.1016/S0040-4020(01)90257-1

n-Alkanones with the carbonyl group at the 2 or central positions (1 and 2, respectively) have been irradiated in the isotropic, smectic B, and two solid phases of n-butyl stearate (BS).The lengths of the ketones were varied from 11 to 31 carbons.The ratios of elimination/cyclization products and diastereomeric cyclobutanol products were measured for each as a function of temperature and BS phase.The effect of 1 and 2 on the phase transition temperatures of BS has been correlated with changes in the product ratios.The experiments demonstrate that a very sensitive cooperative relationship exists between the ease with which 1 and 2 fit into the ordered phases of BS and the degree to which the solvent matrices influence ketone photochemistry.The influence of solvent order on the product ratios is distinctly different for 1 and 2, and for the two product ratios from one ketone.