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STD 12 -8.1. Aldehydes and ketones — JEE STD 11 Science — Question

Gujarat BoardEnglish MediumSTD 11 ScienceJEESTD 12 -8.1. Aldehydes and ketones4 Marks
MCQ
$\underset{\begin{smallmatrix} 
 More\,\,reactive \\ 
 (oxidation) 
\end{smallmatrix}}{\mathop{\begin{matrix}
   O  \\
   ||  \\
   H-C-H  \\
\end{matrix}}}\,$$+ CH _{3}- CH $$\xrightarrow{Conc.NaoH}$

Find out the products of reaction

$\begin{array}{*{20}{c}}
  {C{H_3} - CHC{H_2}CHO} \\ 
  {\,|\,\,\,\,\,\,\,\,\,\,\,\,} \\ 
  {OH\,\,\,\,\,\,} 
\end{array}$

  • ✓
    $CH _{3} CH _{2} OH $ and $ HCO _{2} Na$
  • B
    $CH _{3} CH _{2} OH + CH _{3} OH$
  • C
    $CH _{3} CO _{2} Na $ and $ CH _{3} OH$
  • D
    $CH _{3} CO _{2} Na$ and $HCO _{2} Na$
✓

Answer

Correct option: A.
$CH _{3} CH _{2} OH $ and $ HCO _{2} Na$
a
The given reaction is an example of Cannizzaro reaction. On reaction with concentrated $NaOH$, formaldehyde being more reactive undergoes oxidation and forms salt of sodium formate $\left( HCO _{2} Na \right) .$ Acetaldehyde being less reactive undergoes reduction and forms ethyl alcohol $\left( CH _{3} CH _{2} OH \right)$. The reaction is as follows :

$\underset{\begin{smallmatrix} 
 More\,\,reactive \\ 
 (oxidation) 
\end{smallmatrix}}{\mathop{\begin{matrix}
   O  \\
   ||  \\
   H-C-H  \\
\end{matrix}}}\,$$+$$\underset{\begin{smallmatrix} 
 Less\,\,\,reactive \\ 
 (reduces) 
\end{smallmatrix}}{\mathop{C{{H}_{3}}-CH=O}}\,\xrightarrow{Conc.\,NaoH}$$HCOONa\, + \,C{H_3}C{H_2}OH$

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