question_answer

    When 3,3-dimethyl-2-butanol is heated with \[{{H}_{2}}S{{O}_{4}},\]the major product obtained is

A)  2,2-dimethyl-l-butene

B)  2,3-dimethyl-l-butene

C)  2,3-dimethyl-2-butene

D) \[cis\]and trans isomers of 2,3-dimethyl-2- butane

Correct Answer: C

Solution :

                \[{{H}_{3}}C-\underset{\begin{smallmatrix}  | \\  C{{H}_{3}} \end{smallmatrix}}{\overset{\begin{smallmatrix}  C{{H}_{3}} \\  | \end{smallmatrix}}{\mathop{C}}}\,-\underset{\begin{smallmatrix}  | \\  OH \end{smallmatrix}}{\mathop{CH}}\,-C{{H}_{3}}+cone\text{ }{{H}_{2}}S{{O}_{4}}\] \[\xrightarrow[{}]{\Delta }\underset{(minor)}{\mathop{{{H}_{3}}C-\underset{\begin{smallmatrix}  | \\  C{{H}_{3}} \end{smallmatrix}}{\overset{\begin{smallmatrix}  C{{H}_{3}} \\  | \end{smallmatrix}}{\mathop{C}}}\,-CH=C{{H}_{2}}}}\,+\underset{(major)}{\mathop{C{{H}_{3}}-\overset{\begin{smallmatrix}  C{{H}_{3}} \\  | \end{smallmatrix}}{\mathop{C}}\,=\overset{\begin{smallmatrix}  C{{H}_{3}} \\  | \end{smallmatrix}}{\mathop{C}}\,-C{{H}_{3}}}}\,\] Mechanism Note Most stable alkene is the major product of the reaction. C is and trans isomerism is not possible because similar groups are present on both double bonded carbon atoms.