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Reimer–Tiemann reaction
The Reimer–Tiemann reaction is a chemical reaction used for the ortho-formylation of phenols; with the simplest example being the conversion of phenol to salicylaldehyde. The reaction was discovered by Karl Reimer〔Karl Reimer, Berichte der deutschen chemischen Gesellschaft 9, S. 423–424 (1876). - ()〕 and Ferdinand Tiemann. The Reimer in question was Karl Reimer (1845-1883) not the less known Carl Ludwig Reimer (1856-1921).〔see "Karl Reimer Nachruf 1883.pdf" at Commons and text on page 101.〕
==Reaction mechanism==
Chloroform (1) is deprotonated by strong base (normally hydroxide) to form the chloroform carbanion (2) which will quickly alpha-eliminate to give dichlorocarbene (3); this is the principal reactive species. The hydroxide will also deprotonate the phenol (4) to give a negatively charged phenolate (5). The negative charge is delocalised into the aromatic ring, making it far more nucleophilic and increases its ortho selectivity. Nucelophilic attack of the dichlorocarbene from the ortho position gives an intermediate dichloromethyl substituted phenol (7). After basic hydrolysis, the desired product (9) is formed.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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