Explain the following with suitable examples(i).Clemmensen Reduction(ii).Stephen reaction

(i) Clemmensen Reduction:
The Clemmensen Reduction is a chemical reaction used to reduce ketones and aldehydes to alkanes using amalgamated zinc (Zn(Hg)) and concentrated hydrochloric acid (HCl). It's a powerful method for converting carbonyl groups into methylene (CH2) groups, effectively removing the oxygen atom from the carbonyl compound. This reduction is particularly useful when other methods like Wolff-Kishner reduction (which requires high temperatures) might cause unwanted side reactions.

The mechanism involves the formation of a complex between the carbonyl compound and the zinc amalgam, followed by protonation of the carbonyl oxygen and subsequent reduction of the intermediate complex to an alkane.

Example:
Consider the reduction of acetophenone to ethylbenzene using the Clemmensen Reduction:

Acetophenone
+
Zn(Hg)
+
HCl
→
Ethylbenzene
Acetophenone+Zn(Hg)+HCl→Ethylbenzene

(ii) Stephen Reaction:
The Stephen Reaction is a method for converting a nitrile (RC≡N) to an amine (RCH2NH2) using a metal hydride such as lithium aluminum hydride (LiAlH4) or sodium cyanoborohydride (NaBH3CN). This reaction is particularly useful for the synthesis of primary amines from nitriles.

The mechanism of the Stephen Reaction involves the reduction of the nitrile to an imine intermediate, followed by reduction of the imine to the corresponding amine using the metal hydride.

Example:
Conversion of benzonitrile to phenylamine (aniline) using the Stephen Reaction:

Benzonitrile
+
LiAlH4
→
Phenylamine
Benzonitrile+LiAlH4→Phenylamine

In this reaction, LiAlH4 reduces the nitrile group to an imine, which is further reduced to the amine group, yielding phenylamine.