Sn1 and Sn2 reaction

Nucleophilic substitution reactions are of two types, substitution nucleophllic bimolecular (SN^2) and substitution nucleophilic unimolecular (SN^1) depending on molecules taking part in determining the rate of reaction. Reactivity of alkyl halide towards SN^1 and SN^2 reactions depends on various factors such as steric hindrance, stability of intermediate or transition state and polarity of solvent. SN^2 reaction mechanism is favoured mostly by primary alkyl halide then secondary and then tertiary. This order is reversed in case of SN^1 reactions. SN^1 reaction is fastest in