Question

Assertion :Following is not a suitable technique for the preparation of shown alkane product.

$2H_{3}C-\underset{C{H}_3}{\underset{|}{\stackrel{C{H}_3}{\stackrel{|}{C}}}-}Cl+Na\underset{Heat}{\overset{THF}{\to }}{H}_{3}C-\underset{C{H}_3}{\underset{|}{\stackrel{C{H}_3}{\stackrel{|}{C}}}-}\underset{C{H}_3}{\underset{|}{\stackrel{C{H}_3}{\stackrel{|}{C}}}-}C{H}_3$

Reason: Above mentioned reaction involves a highly unstable tertiary carbanion

• A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
• B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
• C. Assertion is correct but Reason is incorrect
• D. Assertion is wrong but reason is correct.

Answer 1

The correct option is A Both Assertion and Reason are correct and Reason is the correct explanation for Assertion

It is the Wurtz reaction where two alkyl halides are reacted with sodium to form a new alkane:

$2R–X+2Na\to R–R+2N{a}^{+}{X}^{-}$

The reaction involves the formation of carbanion intermediate. In the given reaction the alkyl halide forms tertiary carbanion which is highly unstable due to $+I$ effect of alkyl groups. Hence is not a suitable technique for the preparation of shown alkane product.

$2H_{3}C-\underset{C{H}_3}{\underset{|}{\stackrel{C{H}_3}{\stackrel{|}{C}}}-}Cl+Na\underset{Heat}{\overset{THF}{\to }}{H}_{3}C-\underset{C{H}_3}{\underset{|}{\stackrel{C{H}_3}{\stackrel{|}{C^{\odot }}}}+}NaCl\stackrel{Na}{\to }{H}_{3}C-\underset{C{H}_3}{\underset{|}{\stackrel{C{H}_3}{\stackrel{|}{C^{-}}}}}N{a}^{+}\stackrel{H_{3}C-\underset{C{H}_3}{\underset{|}{\stackrel{C{H}_3}{\stackrel{|}{C}}}-}Cl}{\to }{H}_{3}C-\underset{C{H}_3}{\underset{|}{\stackrel{C{H}_3}{\stackrel{|}{C}}}-}\underset{C{H}_3}{\underset{|}{\stackrel{C{H}_3}{\stackrel{|}{C}}}-}C{H}_3$