Meerwein arylation

The Meerwein arylation - also known as the Meerwein reaction - is a name reaction in organic chemistry that goes back to the German chemist Hans Meerwein (1879–1965). The reaction was first published in 1939.

Overview reaction

In the Meerwein arylation, an aryldiazonium salt (e.g. phenyldiazonium chloride ) is combined with an alkene ( 1 ) with the addition of copper salts, e.g. B. copper (II) chloride (CuCl ₂ ) brought to reaction. Either a mixture of cis - and trans -3-phenylacryl ( cis , trans - 2 ) and / or 2-chloro-3-phenylpropane ( 3 ) is formed:

Reaction mechanism

A possible reaction mechanism for the Meerwein arylation is described by Zerong Wang as follows:

The aryldiazonium salt reacts with the addition of copper (I) chloride (CuCl) to form a phenyl radical, thereby forming nitrogen (N ₂ ) and copper (II) chloride (CuCl ₂ ) . The phenyl radical reacts with the addition of an alkene ( 1 ) to form a phenylpropane radical . The radical reduces the copper (II) chloride (CuCl ₂ ) to copper (I) chloride (CuCl) and forms a carbenium ion on the phenylpropane, which either by splitting off a proton to form 3-phenyl acrylic acid (Z = CO ₂ H; cis , trans - 2 ) reacts or by reaction with a chloride ion and to form 2-chloro-3-phenylpropionic acid (Z = CO ₂ H; 3 ).

Individual evidence

1. ↑ ^{a b c} Zerong Wang: Comprehensive Organic Name Reactions and Reagents, Volume 2 . John Wiley, Hoboken (NJ) 2009, ISBN 978-0-470-28662-3 , pp. 1866-1870 .