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Question
Explain the following reactions:
Stephan reaction
Solution
This reaction is used to synthesize aldehydes from nitriles or cyanides. Firstly, nitriles or cyanides are reduced in presence of stannous chloride and hydrochloric acid in ethyl acetate solvent to form imine intermediate. Then hydrolysis of this intermediate with water gives the corresponding aldehyde.
\[\ce{CH3 - C ≡ N + 2[H] ->[SnCl2/HCl][Ether] CH3 - CH = NH + HCl ->[H2O/H^+] \underset{Acetaldehyde}{CH3CHO} + NH4Cl}\]
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| Column I (Example) |
Column II (Reaction) |
||
| (i) | \[\begin{array}{cc} \phantom{...}\ce{O}\phantom{..............................}\ce{O}\phantom{}\\ \phantom{...}||\phantom{..............................}||\phantom{}\\ \ce{CH3 - C - Cl + H2 ->[Pd - C/BasO4] CH3 - C - H} \end{array}\] |
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| (ii) |  |
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| (iii) |  |
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| (iv) | \[\begin{array}{cc} \ce{R - CH2 - COOH ->[Br/Red P] R - CH - COOH}\\ \phantom{.....................}|\\ \phantom{.......................}\ce{Br} \end{array}\] |
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| (vi) | \[\ce{2CH3CHO ->[NaOH] CH3 - CH = CHCHO}\] | (f) | Stephen’s reaction |
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