Polar Substituent Effects in the Solvolysis of Acyclic Tertiary Chlorides Polar Effects VI

Abstract

AbstractThe influence of twenty substituents R on the solvolysis rates and products of tertiary chlorides R ‐ CH2CH2C(CH3)2Cl (7) has been studied. H, CH3, (CH3)2NCH2, ClCH2, Cl, CN and NO2 exert an inductive effect only, as the good correlation of the rates with the corresponding inductive substituent constants σ shows. Bulkier alkyl groups, i.e. isopropyl and t‐butyl, lower the rate due to a Baker‐Nathan effect, while the n‐electron donors CH3S, CH3O, HO and (CH3)2N and the σ‐electron donors (CH3)3Sn and HOCH2 cause rate increases based on σ constants. These accelerations are attributed to C,C‐hyperconjugative and inductomeric effects which arise in the transition state for ionization. A comparison of the reactivity of the acyclic chlorides 7 and the corresponding 1‐R‐substituted 3‐bromoadamantanes 1a shows that polar substituent effects are more strongly transmitted in the rigid bicyclic compounds 1a than in the flexible acyclic compounds 7.