Abstract: The reactions of three β-diketones with chloranil in C₆D₆ under UV irradiation were investigated by the chemically induced dynamic nuclear polarization(CIDNP).The results show that a hydrogen abstraction interaction between chloranil and β-diketones was involved. As a result, singlet multiplicity stable neutral radical pairs(RP) were formed, as intermediates,producing CIDNP polarizations.RP recombined to develop the new OH group of phenol polarizations of the recombination compounds.

Key words: β-diketones, chloranil, CIDNP