Nucleophilic Conjugate Substitution – The S_N2′ Mechanism

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This subclass of nucleophilic substitution occurs when the nucleophile (HS^–) attacks the alkene instead of the saturated carbon – the S_N2′ mechanism. This is the due to the saturated carbon being hindered (it is a secondary carbon), making the regular S_N2 mechanism less favourable.

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Alternatively, use these links: (Substrate: Nucleophile)

Allyl chloride : SH | Benzyl chloride : SH | 2^o benzyl chloride : SH | 2^o allyl chloride : SH (S_N2′)

R. H. DeWolfe and W. G. Young, Chem. Rev., 1956, 56, 753–901.

J. W. Hill and A. Fry, J. Am. Chem. Soc., 1962, 84, 2763–2769.