Photolysis of butane-2,3-dione in fluorocarbon solvents; a chemically induced nuclear polarization (CIDNP) study

Abstract

CIDNP observations of the polarized signals from products of radical reactions in solution of neat butane-2,3-dione in perfluorocyclohexane and perfluorodecalin, and in solutions with added radical scavenger or hydrogen donor, are consistent with three primary processes. Threr are symmetric (probably) and unsymmetric fragmentation and hydrogen-abstraction by triplet butane-2,3-dione from the starting material, and each yields free radicals. In all solutions the mechanisms of ensuing reactions are suggested. In the presence of CCl₄ and CCl₃Br pair substitution effects dominate the CIDNP behaviour. When high concentrations of propan-2-ol are present evidence is given for reaction of the excited singlet state of the parent molecule.