Question

What is reimer tiemen reaction??

Answer 1

Hi,

Here is your answer, REIMER-TIEMANN REACTION Treatment of phenol with ''chloroform'' in presence of aqueous sodium or potassium hydroxide at 340 K followed by hydrolysis of the resulting product gives 2-hydroxybenzaldehyde (salicyaldehyde) as the major product. This reaction is called Reimer-Tiemann Reaction. A small amount of p-hydroxyaldehyde is also formed. In Reimer-Tiemann reaction, the o-isomer predominates due to chelation, but if one of the o-position is occupied, the -CHO group goes to the p-position.Example :- Guaiacol forms Vanilin In some cases, the p-position is occupied , the -CHO group as expected goes to the o-position but at the same time some cyclohexadienone containing group is also formed.MECHANISM Note:- If you talk about only for Board Examination then mechanism is not necessary. But if we take competitive exams into consideration then it is very important Example:- (JEE Mains + Advance , BITSAT , NDA ) Mechanism :- Reimer-Tiemann reaction is an ''Electrophilic Substitution reaction and occurs through the following steps:- Generation of electrophile:- HO⁻ + CHCL₃ ⇄ H₂O + CCl⁻₃ -----------> CCl₂ + CI⁻Please see the attached file!! Hope it helps you !

Answer 2

Hey !!

Phenol when treated with chloroform in the presence of sodium hydroxide, a -CHO groups is introduced at ortho position of benzene ring forming salicylaldehyde. The intermediate substituted benzal chloride is hydrolysed in the presence of alkali to produce ortho hydroxy benzaldehyde. This reaction is known as ''Reimer-Tiemann reaction''. The electrophile is : CCl₂

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