kolbe reaction is a type of phenol reaction. in which phenol is react with sodium hydroxide, phenoxide ion is generated. this is first step reaction and in second step reaction, phenoxide ion again react with CO2 and acidification (H+). then it give ortho hydroxy benzoic acid. this product is also know as salicylic acid.

Kolbe reaction equation

kolbe reaction is a type of addition reaction or is a type of phenolic reaction. In which phenol is taken first, in this case phenol does not have a direct reaction.

the acidic hydrogen of phenol has to be removed. acidic hydrogen can be remove with the help of naoh (sodium hydroxide). this is shown in the reaction. and reaction is,

In this reaction, acidic hydrogen of phenol will be remove by naoh. and this reaction will form sodium phenoxide. Now, sodium phenoxide react with CO2 and also does acidification.

When sodium phenoxide react with CO2. and acidification (H+) after this reaction, hydroxyl group (COOH) comes to ortho position. this is called kolbe reaction.

Why sodium phenoxide react with CO2 then COOH comes to ortho position?

Resion is, intermolecular hydrogen bonding occur between oxygen and hydrogen. that’s why hydroxyl group attached on ortho position.

this product is know as ortho hydroxyl benzoic acid. it is also called salicylic acid.