Delépine reaction
The Delépine reaction is a name reaction in organic chemistry and named after the French chemist Marcel Delépine (1871–1965). It describes the synthesis of primary amines by acid hydrolysis of quaternary hexamethylenetetramine salts, which are accessible from the reaction of benzyl or alkyl halides with hexamethylenetetramine.
Reaction mechanism
The mechanism is explained using an alkyl chloride. The use of alkyl bromides is also possible. The hexamethylenetetramine 1 reacts with benzyl or alkyl halide 2 to form a quaternary ammonium salt 3 , only one nitrogen atom being alkylated. This quaternary ammonium salt decomposes in several reaction steps to a hydrohalide 11 by heating under reflux in concentrated, ethanolic hydrochloric acid solution . By- products of the reaction are formaldehyde , which reacts with the ethanol present in the solution to form formaldehyde diethyl acetal, and ammonium chloride . After a basic work-up, the desired amine 12 is formed .
Advantages of this reaction are the selective access to primary amines (no side reactions) from easily accessible starting materials and short reaction times under relatively simple reaction conditions. An example is the synthesis of 2-bromoallylamine from 2,3-dibromopropene.
Individual evidence
- ↑ M. Delépine: Sur l'hexamethylene-amine (suite). Solubilities, hydrates, bromides, sulfates, phosphates. In: Bull. Soc. Chim. France (3). 13, 1895, pp. 352-361.
- ↑ Alexander R. Surrey: Name Reactions in Organic Chemistry . 2nd ed., Academic Press, 1961.
- ^ Z. Wang: Comprehensive Organic Name Reactions and Reagents. 3-volume set. Volume 1, Wiley, 2009, ISBN 978-0-471-70450-8 , p. 865.
- ^ Albert T. Bottini, Vasu Dev, Jane Klinck: 2-Bromoallylamine . In: Organic Synthesis . Vol. 5, 1973, p. 121.