STEREOCHEMISTRY OF NUCLEOPHILIC SOLVENT PARTICIPATION IN THE DECOMPOSITION OF DIACYL PEROXIDES

Decomposition of (S)-(+)-m-chlorobenzoyl 2-methylbutanoyl peroxide in acetonitrile yields, among other products, N-acetyl-N-m-chlorobenzoyl-2-butylamine with 14.4% net inversion of configuration. Similar nucleophilic participation is observed in acetic acid and 2-butanol to yield 2-butyl acetate (14% net inversion) and di-2-butyl ether. In these solvents and in cyclohexane and CCl4, carboxyl inversion product (m-chlorobenzoyl-2-butylcarbonate), on the other hand, is formed with retention of configuration. Decomposition of cis-and trans-4-/tert-butylcyclohexylformyl m-chlorobenzoyl peroxide gives somewhat more complex stereochemical results, but again products involving solvent capture in acetonitrile, acetic acid, and 2-butanol show largely loss of original stereochemistry. Chemically induced dynamic nuclear polarization experiments with several peroxides show no evidence of polarization in any carbonyl-containing products. These results are discussed on the basis of a single rate-determining step in the polar and radical decompositions of diacyl peroxides and the lifetimes of intermediate ion radical pairs. © 1979, American Chemical Society. All rights reserved.