Norrish Type I Cleavage of Aliphatic Carboxylic Acids and Esters in Solution. A CIDNP.‐study

UV.‐irradiation of pivalic and isobutyric acid and their methyl esters as well as of α‐hydroxy isobutyric and malonic acid in solution lead to chemically induced dynamic nuclear polarization (CIDNP.) of parent compounds and of various reaction products. CIDNP.‐effects and product distributions confirm α‐cleavage of the C(α), CO bond to be the major mode of photodecomposition. Scavenger experiments indicate that decomposition of the molecules from a triplet excited state is roughly equally or more probable than from a singlet excited state. Quantum yields of educt disappearance are also given for the methyl esters of pivalic and isobutyric acid.