Forster–Decker method
{{Short description|Series of chemical reactions}}
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).{{Cite journal | last1 = Forster | first1 = Martin Onslow| author-link = Martin Onslow Forster| doi = 10.1039/CT8997500934 | title = XCI.–Influence of substitution on specific rotation in the bornylamine series | journal = Journal of the Chemical Society, Transactions| volume = 75 | pages = 934–935 | year = 1899 | url = https://zenodo.org/record/1763692}}Decker, H.; Becker, P. Ann. 1913, 395, 362. The process occurs by way of transient formation of an imine (3) that undergoes the actual alkylation reaction.
Process stages
- Conversion of the primary amine to an imine (Schiff base) using an aldehyde.{{cite book |last= McMurry |first= John |date= 1988 |title= Organic Chemistry |edition= Second |publisher= Brooks/Cole Publishing Company |page= 674-675|isbn= 0-534-07968-7}}
- Alkylation of the imine using an alkyl halide, forming an iminium ion.{{cite web |url=https://synarchive.com/named-reactions/forster-decker-amine-synthesis |title=Forster-Decker Amine Synthesis |author= |date=2011–2022 |website=SynArchive.com The Organic Synthesis Archive |access-date=December 12, 2022}}
- Hydrolysis of the iminium, releasing the secondary amine and regenerating the aldehyde. {{cite web |url=https://www.chemistrysteps.com/imine-and-enamine-hydrolysis-mechanism/ |title=Imine and Enamine Hydrolysis Mechanism |author= |date=2016–2022 |website=Chemistry Steps |access-date=December 13, 2022}}
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 SN2-type process can.