Barbier-Wieland dismantling
The Barbier-Wieland degradation is a name reaction of organic chemistry , which was published in 1912 by Heinrich Wieland (1877–1957) and in 1913 by Philippe Antoine François Barbier (1848–1922). During the reaction, the carbon chain of a higher-order aliphatic carboxylic acid is shortened by one carbon atom.
Overview reaction
The degradation takes place in several reaction steps ( esterification , Grignard reaction , elimination reaction , oxidation ).
Reaction mechanism
In the proposed reaction mechanism, the carboxylic acid 1 is first esterified. The resulting carboxylic acid ester 2 then reacts with a Grignard compound under a Grignard reaction. After intermediate 3 has formed, the second Grignard reaction follows. The result is alcohol 4 . This is followed by acetylation with acetic anhydride (Ac 2 O), whereupon a new ester 5 is formed. After the acetic acid is split off , the alkene 6 is formed , which is broken down to the desired carboxylic acid 7 by oxidative cleavage of the C = C double bond .
modification
The degradation can also be applied with other oxidizing reagents and Grignard compounds.
application
In the 1930s to 1950s, the Barbier-Wieland mining was used for the structural clarification of acids.
See also
Individual evidence
- ↑ a b c d Wang, Zerong (Daniel Zerong): Comprehensive organic name reactions and reagents . John Wiley, Hoboken, NJ 2009, ISBN 978-0-471-70450-8 , pp. 210-214 .
- ↑ Namboothiri, I. (Irishi): Organic syntheses based on name reactions: a practical guide to 750 transformations . 3rd ed.Elsevier, Amsterdam 2012, ISBN 978-0-08-096631-1 , pp. 30 .
- ↑ James A. Moore, Clarisse L. Habraken: Heterocyclic Studies. XV. 5-methyl-4-phenylpyrazole-1-acetic acid. An Oxidation Product of 2,3-Dihydro-5-methyl-6-phenyl-4H-1,2-diazepin-4-one *, 1 . In: The Journal of Organic Chemistry . tape 30 , no. June 6 , 1965, p. 1889-1892 , doi : 10.1021 / jo01017a040 .