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Question
Through which of the following reactions number of carbon atoms can be increased in the chain?
(i) Grignard reaction
(ii) Cannizaro’s reaction
(iii) Aldol condensation
(iv) HVZ reaction
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Solution
(i) Grignard reaction
(iii) Aldol condensation
Explanation:
Grignard reagent is used to add number of carbon atom in chain.
\[\begin{array}{cc}
\phantom{....................}\ce{R'}\\
\phantom{...................}|\\
\ce{RCHO + R'MgX ->[H2O] R - CH - OH}
\end{array}\]
Aldol condensation involves condensation of aldehydes and ketones with α-hydrogen.
\[\begin{array}{cc}
\ce{CH3CHO ->[dil NaOH] CH3CHCH2CHO ->[Δ][-H2O] CH3CH = CHCHO}\\
|\phantom{..............}\\
\ce{\underset{Aldol}{OH}\phantom{............}}\\
\end{array}\]
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