Forster–Decker method explained

The Forster–Decker method is a series of chemical reactions that have the effect of mono-alkylating a primary amine (1), forming a secondary amine (6).^{[1] [2]} The process occurs by way of transient formation of an imine (3) that undergoes the actual alkylation reaction.

Process stages

1. Conversion of the primary amine to an imine (Schiff base) using an aldehyde.^[3]
2. Alkylation of the imine using an alkyl halide, forming an iminium ion.^[4]
3. Hydrolysis of the iminium, releasing the secondary amine and regenerating the aldehyde. ^[5]

Because the actual alkylation occurs on the imine, over-alkylation is not possible. Therefore, this method does not suffer from side-reactions such as formation of tertiary amines as a simple S_N2-type process can.

See also

• Reductive amination

Notes and References

1. Forster . Martin Onslow. Martin Onslow Forster. 10.1039/CT8997500934 . XCI.–Influence of substitution on specific rotation in the bornylamine series . Journal of the Chemical Society, Transactions. 75 . 934–935 . 1899 .
2. Decker, H.; Becker, P. Ann. 1913, 395, 362.
3. Book: McMurry, John . 1988 . Organic Chemistry . Second . Brooks/Cole Publishing Company . 674-675. 0-534-07968-7.
4. Web site: Forster-Decker Amine Synthesis . . 2011–2022 . SynArchive.com The Organic Synthesis Archive . December 12, 2022.
5. Web site: Imine and Enamine Hydrolysis Mechanism . . 2016–2022 . Chemistry Steps . December 13, 2022.