The Formation of Alkyl Cyanides

Alkyl cyanides have been prepared by three major variations of the phase transfer method. These include the liquid-liquid phase transfer method (including catalysis by quats and amines), the crown catalyzed solid-liquid method and the tri-phase catalytic method. Each of these methods has been discussed with reference to the mechanism in the preceding section and it remains largely to exemplify these approaches. It should be noted, however, that numerous stoichiometric syntheses of aliphatic nitriles are available, including those involving dipolar aprotic solvents [12]. 

Stoichiometric amounts of tetraethylammonium cyanide react with aliphatic bromides in dichloromethane, acetonitrile or DMSO to give reasonable yields of the corresponding nitriles [13]. These reactions are clearly related to, but not actually examples of, phase transfer catalysis. It is interesting, however, that under these homogeneous conditions, tetraethylammonium cyanide reacts in acetonitrile with neopentyl bromide to give the corresponding nitrile (see Eq. 7.3). Bimolecular displacements on such sterically hindered substrates are usually quite difficult to effect. 

The preparation of a number of aliphatic nitriles is tabulated below (Table 7.1). Several examples which are noncatalytic are included in this table for the benefit of the reader interested more in the product than in the mode of synthesis. 

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