Question

$S_{N}2$ mechanism is involved in the following substitution

• A. $C{H}_3-C{H}_2-Cl+O{H}^{-}$
• B. $C{H}_3-\underset{\stackrel{|}{C}{H}_3}{\stackrel{\underset{|}{C}l}{C}}-C{H}_3+O{H}^{-}$
• C. $C{H}_3-\stackrel{\underset{|}{C}l}{C}H-C{H}_3+O{H}^{-}$
• D. $C{H}_3-C{H}_2-\underset{\stackrel{|}{C}{H}_3}{\stackrel{\underset{|}{C}l}{C}}-C{H}_3+O{H}^{-}$

Answer 1

Answer: (A)

$S_{N}2$ mechanism means bimolecular nucleophilic substitution mechanism. In this, rate of reaction is determined by concentration of two molecules. It is characteristic of $1^{\circ }$ alkyl halides.
(a) $C{H}_3-\underset{1^{\circ }\text{alkyl halide}}{C{H}_2-Cl}+O{H}^{-}$
(b) $\underset{3^{\circ }\text{alkyl halide}}{C{H}_3-\underset{\stackrel{|}{C}{H}_3}{\stackrel{\underset{|}{C}l}{C}}-C{H}_3}+OH$
(c) $\underset{2^{\circ }\text{alkyl halide}}{C{H}_3-\underset{\stackrel{|}{C}l}{C}H-C{H}_3}6O{H}^{-}$
(d) $C{H}_3-\underset{3^{\circ }\text{alkyl halide}}{C{H}_2-\underset{\stackrel{|}{C}{H}_3}{\stackrel{\underset{|}{C}l}{C}}-C{H}_3}+O{H}^{-}$