Horenstein-Pählicke reaction
The Horenstein-Pählicke reaction is a name reaction in organic chemistry in which halogen derivatives of tertiary amines react with salts of aromatic carboxylic acids . It was first described in 1938 by Heinrich Horenstein and Herrmann Pählicke .
Overview reaction
In this reaction, a tertiary amine is attached to a carboxyl group through a nucleophilic substitution .
Reaction mechanism
The figure shows the postulated course of the reaction:
The carboxylic acid 1 is deprotonated with a base (e.g. potassium carbonate ) . The carboxylate 2 then reacts with the halogen derivative of the tertiary amine. In an S N 2 substitution, esterification now occurs, as in FIG . 3 .
The reaction is generally carried out in boiling toluene. However, it has been found that the reaction proceeds in higher yield in butanol. The yield can be increased again if the carboxylic acid and the alkyl halide react directly with one another. This reaction can be used to esterify amino alcohols, it being possible to use bromine derivatives in addition to the chlorine derivatives shown here.
Atomic economy
Since this reaction uses halogen derivatives which only split off their halogen, this reaction has good atom economy. Only the base and the split off halogen are obtained as by-products.
Individual evidence
- ↑ a b c Zerong Wang: Comprehensive Organic Name Reactions and Reagents, 3 Volume Set . John Wiley & Sons, Hoboken, New Jersey 2009, ISBN 978-0-471-70450-8 , pp. 1481-1482.
- ↑ Helmut Krauch and Werner Kunz: reactions of organic chemistry. A contribution to the terminology of organic chemistry . 5th ed. Dr. Alfred Hüthig Verlag GmbH, Heidelberg 1976, ISBN 3-7785-0363-4 , p. 731.