Photochemische Primärreaktionen α-verzweigter aliphatischer Ketone und Aldehyde in lösung†

UV.-Irradiation of methyl t-butyl ketone, di-t-butyl ketone, pivalaldehyde and isobutyraldehyde in benzene solution leads to chemically induced dynamic nuclear polarization (CIDNP.) of the parent compounds and of various reaction products. CIDNP.-effects and product distributions establish type I α-cleavage predominantly of triplet state molecules as the major primary photochemical step for all the four α-branched carbonyl compounds. In chlorinated solvents singlet reactions interfere with the triplet processes.