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The Gabriel synthesis, named for the German chemist Siegmund Gabriel, is a chemical reaction that transforms primary alkyl halides into primary amines using potassium phthalimide.1234
The sodium or potassium salt of the product reacts with a primary alkyl halide to form an alkyl phthalic imide. The reaction fails with secondary alkyl halides.
Upon workup by acidic hydrolysis the primary amine is liberated as the amine salt.5 Alternatively the workup may be via the Ing-Manske procedure, involving reaction with aqueous or ethanolic hydrazine at reflux. This produces a precipitate of phthalhydrazide along with the primary amine. The first technique often produces bad yields or side products; separation of phtalhydrazide can be unpleasant. For these reasons, other methods for liberating the amine from the phthalimide exist.6
References
- ^ Gabriel, S. (1887). "Ueber eine Darstellung primärer Amine aus den entsprechenden Halogenverbindungen". Ber. 20: 2224, http://gallica.bnf.fr/ark:/12148/bpt6k90711d/f133.chemindefer.
- ^ Sheehan, J. C.; Bolhofer, V. A. (1950). "An Improved Procedure for the Condensation of Potassium Phthalimide with Organic Halides". J. Am. Chem. Soc. 72: 2786. doi:.
- ^ Gibson, M.S.; Bradshaw, R.W. (1968). "The Gabriel Synthesis of Primary Amines". Angew. Chem. Int. Ed. Engl. 7: 919. doi:.
- ^ Mitsunobu, O. Comp. Org. Syn. 1991, 6, 79-85. (Review)
- ^ Khan, M. N. (1995). "Kinetic Evidence for the Occurrence of a Stepwise Mechanism in the Hydrazinolysis of Phthalimide". J. Org. Chem. 60: 4536. doi:.
- ^ Osby, J. O.; Martin, M. G.; Ganem, B. (1984). "An Exceptionally Mild Deprotection of Phthalimides". Tetrahedron Lett. 25 (20): 2093. doi:.
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