3-(cyclohex-2-enyloxy)propionitrile (prepared, 1 equiv)
sodium peroxide (Lancaster, >1 equiv)
distilled water (3.5 ml/ mmol)
ether

The nitrile is mixed with water at 50°C. Sodium peroxide is added very slowly (usually about a few grains every 5 minutes) until the reaction is complete. The amount of sodium peroxide required varies. If added very slowly, only about 1.5 equivalents may be required. The reaction can be said to be complete when there is only one layer remaining (i.e. the product is miscible, but the nitrile is not), although continuing the addition for a little while after this point, then leaving to stir seems to improve the results. The mixture is extracted with ether to remove any nitrile still present, then slowly acidified to pH 5 with conc. HCl, and extracted with ether which, after drying, gives pure carboxylic acid (75%).

Good yields possible with care. The temperature control is important. If it is too low then the reaction is very slow. If it is too high, yields are reduced. It is also very easy for too much sodium peroxide to be added, in which case a bright flame can be seen at the water surface. This can happen at 50°C, but is easier to prevent. Presumably this does no good, but yields were not found to be drastically reduced when this occurred. The mixture always goes cloudy, and fizzes on addition of the peroxide, and the next portion should not be added until after this has cleared. Any recovered starting material from initial extraction is also pure, and can be reused. The reaction was only performed on the nitrile shown, which was sensitive to normal hydrolyses. It should be viable for other sensitive nitriles. The sodium peroxide was obtained from Lancaster in small grains. They appear to now to supply it in larger particles. Whether this affects the reaction is unclear.

CDCl₃ 1.50-2.10 (6H, m), 2.57-2.63 (2H, m), 3.86-3.76 (2H, m), 3.93 (1H, m) 5.75-5.91 (2H, m).

A. J. McCarroll and J. C. Walton, J. Chem. Soc., Perkin Trans. 2, 2000, 2399.

M. Huhtasaari, H. J. Schäfer and L. Becking, Angew. Chem., Int. Ed. Engl., 1984, 23, 980. H. L. Vaughn and M. D. Robbins, J. Org. Chem., 1975, 40, 1187 Synthesis of nitrile: H. A. Bruson, Org. React. (N. Y.), 1949, 5, 79. J. H. McGregor and C. Pugh, J. Chem. Soc., 1945, 535.