Chemistry:Von Braun reaction
| von Braun reaction | |||||||||
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| Named after | Julius von Braun | ||||||||
| Reaction type | Substitution reaction | ||||||||
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The von Braun reaction is an organic reaction in which a tertiary amine reacts with cyanogen bromide to an organocyanamide.[1] An example is the reaction of N,N-dimethyl-1-naphthylamine:[2]
von Braun reaction
These days, most chemists have replaced cyanogen bromide reagent with chloroethyl chloroformate as the reagent of choice instead for the demethylation of tertiary amines. It appears as though Olofson et al. was the first chemist to have reported this.[3][4]
Reaction mechanism
The reaction mechanism consists of two nucleophilic substitutions: the amine is the first nucleophile displacing the bromine atom which then acts as the second nucleophile.[5][6] In following the mechanism is described using trimethylamine as example:[7]
First, the trimethylamine reacts with the cyanogen bromide to form a quaternary ammonium salt, which in the next step reacts by splitting off bromomethane to give the dimethylcyanamide. This is a bimolecular nucleophilic substitution (SN2).
See also
References
- ↑ J. von Braun; K. Heider; E. Müller (1918). "Bromalkylierte aromatische Amine. II. Mitteilung". Chem. Ber. 51 (1): 273–282. doi:10.1002/cber.19180510132. https://zenodo.org/record/1426635.
- ↑ Homer W. J. Cressman (1947). "N-Methyl-1-Naphthylcyanamide". Org. Synth. 27: 56. doi:10.15227/orgsyn.027.0056.
- ↑ "A new reagent for the selective, high-yield N-dealkylation of tertiary amines: improved syntheses of naltrexone and nalbuphine". The Journal of Organic Chemistry 49 (11): 2081–2082. June 1984. doi:10.1021/jo00185a072. https://pubs.acs.org/doi/abs/10.1021/jo00185a072.
- ↑ Roy A. Olofson & Joseph P. Pepe, U.S. Patent 4,141,897 (1979 to SALFLEX Inc, Pennsylvania Research Corp).
- ↑ Template:March4th
- ↑ Howard A. Hageman (1953). "The Von Braun Cyanogen Bromide Reaction". Organic Reactions 7 (4): 198–262. doi:10.1002/0471264180.or007.04. ISBN 0471264180.
- ↑ Jie Jack Li (2014) (in German), Name reactions: A collection of detailed mechanisms and synthetic applications (5th ed.), Cham: Springer, p. 619, doi:10.1007/978-3-319-03979-4, ISBN 978-3-319-03979-4
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