Phenyleffekte bei radikalischen Additionen an Alkene

Phenyl Effects in Radical Additions to Alkenes Reactions of cyclohexylmercuric salts 4 with NaBH 4 in the presence of alkenes 8 yield products 10 . The main step of the reaction sequence, the addition of a cyclohexyl radical ( 7 ) to alkene 8 , can be measured using a competition technique. The data show that styrene reacts 30‐40 times faster than expected by the σ   − p ‐value. This phenyl effects decreases in going from monosubstituted alkenes 8 to disubstituted alkenes 3, 2 and 1 because the steric hindrance of a coplanar orientation of the π‐system increases in the same order.