question_answer

\[{{S}_{N}}2\]mechanism is involved in the following substitution

A)  \[C{{H}_{3}}-C{{H}_{2}}-Cl+O{{H}^{-}}\]

B)  \[C{{H}_{3}}-\underset{C{{H}_{3}}}{\overset{Cl}{\mathop{\underset{|}{\overset{|}{\mathop{C}}}\,}}}\,-C{{H}_{3}}+O{{H}^{-}}\]

C)  \[C{{H}_{3}}-\overset{Cl}{\mathop{\overset{|}{\mathop{CH}}\,}}\,-C{{H}_{3}}+O{{H}^{-}}\]

D)  \[C{{H}_{3}}-C{{H}_{2}}-\underset{C{{H}_{3}}}{\overset{Cl}{\mathop{\underset{|}{\overset{|}{\mathop{C}}}\,}}}\,-C{{H}_{3}}+O{{H}^{-}}\]

Correct Answer: A

Solution :

                \[{{S}_{N}}2\]mechanism means bimolecular nudeophilic substitution mechanism. In this, rate of reaction is determined by concentration of two molecules. It is characteristic of \[1{}^\circ \] alkyl halides. (a) \[\underset{1{}^\circ \,alkyl\,halide}{\mathop{C{{H}_{3}}-C{{H}_{2}}-Cl+O{{H}^{-}}}}\,\]  (b)\[\underset{3{}^\circ \,alkyl\,\,halide}{\mathop{C{{H}_{3}}-\underset{C{{H}_{3}}}{\overset{Cl}{\mathop{\underset{|}{\overset{|}{\mathop{C}}}\,}}}\,-C{{H}_{3}}+OH}}\,\]  (c)\[\underset{2{}^\circ \,alkyl\,halide}{\mathop{C{{H}_{3}}-\underset{Cl}{\mathop{\underset{|}{\mathop{CH}}\,}}\,-C{{H}_{3}}+O{{H}^{-}}}}\,\]  (d)\[\underset{2{}^\circ \,alkyl\,halide}{\mathop{C{{H}_{3}}-C{{H}_{2}}-\underset{C{{H}_{3}}}{\overset{Cl}{\mathop{\underset{|}{\overset{|}{\mathop{C}}}\,}}}\,-C{{H}_{3}}+O{{H}^{-}}}}\,\]