Riemer Tiemann reaction

              Reimer Tiemann reaction 

Table contents:

History

About reaction

Mechanism

Comparasion

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History-

Riemer Tiemanm reaction is discovered by karl reimer ( 1845-1883 ) and Ferdinand Tiemann ( 1856-1883 ).

About reaction-

Riemer Tiemann reaction is substitution reaction . This reaction used for the orthoformylation of phenols.

When phenol is treated with chloroform in the presence of sodium hydroxide,an aldehyde group introduced at the ortho position. The reaction is called reimer tiemann reaction.

Mechanism-

1.Deprotonation of chloroform in the presence of strong base ( sodium hydroxide) 

And now chloroform carbanion forms.

2.chloroform carbanion undergoes alpha elimination and now dichlorocarbene formed as product.

3.sodium hydroxide deprotonates the phenol reagent.

4.Negative charged is delocalized into the benzene ring.

5. Nucleophile attack on the dochlorocarbene, forming an intermediate chloromethyl substituted phenol.

6.Finally we achieve hydroxy benzaldehyde.

👉👉 Phenol is converted into hydroxy benzaldehyde via chloroform.Carbene is highly electron deficient due to electron withdrawing nature of its two chlorine group.

Comaparasion to other methods-

Directly we can formylation of aromatic compounds bh various method such as the gattarmann reaction, gattarman koch reaction, and Duff reaction, haak reaction but the safety of reaction the Reimer Tiemann reaction is the most advantage routine in chemical synthesis.

➡️ Riemer Tiemann reaction can be useful to yield phenolic acids by carbon tetrachloride product will be salicylic acid rather than the salycyladehyde.