Reimer Tiemann,s Reaction

When phenol is treated with chloroform (CHCl₃) in presence of sodium hydroxide (NaOH) to produce salicylaldehyde ( ortho Hydroxybenzaldehyde) is known as Reimer Tiemann,s Reaction.

This reaction is actually formylation (Addition of -CHO group) of phenol at ortho position.

Short Mechanism:-

Wolf Kishner,s Reduction Reaction

The reaction in which carbonyl group/ compound is first treated with hydrazine and than treated with base to produce alkane is called Wolf Kishner,s Reduction Reaction. In this reaction C=O group is converted into -CH₂-group.

Clemmensen,s Reduction

The reaction in which carbonyl group (C=O) is reduced into (-CH2-) group on reacting with a mixture of zinc and hydrochloric acid is called Clemmensen,s Reduction.

General reaction:-

Reaction of aliphatic aldehyde and ketones-

Reaction of aromatic aldehyde and ketones-

Question:- Why did a mixture of Zn+HCl is used for reduction ?
Answer:- Zn reaction reacts with HCl to produce H₂gas which reduces carbonyl (C=O) to alkane (-CH₂-).

Question:- Why does amalgam of Zinc (Zn/Hg) use in spite of only Zn ?
Answer:- Zn reacts with HCl to produce H₂ very fast that move out fast from reaction mixture and carbonyl compound has very little time to react and most of hydrogen moves out of reaction mixture without reacting whereas in form of amalgam, Zn reacts slowly to produce hydrogen slowly, which can react with carbonyl compound. because only those Zn atoms reacts with HCl which are present on the surface of amalgam .

Amalgam: The solution of metal in mercury is called amalgam. Metal dissolve in mercury like salt dissolve in water.

Haloform reaction

The reaction in which carbonyl compound having three alpha hydrogen treated with a mixture of halogen and sodium hydroxide to give haloform means trihalomethane.

NaOH reacts with X₂ to produce NaOI which replaces three hydrogen by three halogen atom. here halogens are Cl2, Br2 or I2.

Alpha, beta, gama and delta Carbon / Hydrogen .
1. First carbon / hydrogen from functional group (in this case it is OH) is called ALPHA carbon and hydrogen present on alpha carbon is called ALPHA hydrogen.
2. Second carbon / hydrogen from functional group (in this case it is OH) is called BETA carbon and hydrogen present on alpha carbon is called BETA hydrogen.
3. Third carbon / hydrogen from functional group (in this case it is OH) is called GAMA carbon and hydrogen present on alpha carbon is called GAMA hydrogen.
4. Forth carbon / hydrogen from functional group (in this case it is OH) is called DELTA carbon and hydrogen present on alpha carbon is called DELTA hydrogen.