SOME APPLICATIUNS OF RANEY NICKEL TO SYNTHETICAL AND CONSTITUTIONAL PROBLEMS

Among the most widely used reduction catalysts is nickel, prepared according to Raney1 by treating a nickel aluminium alloy' with warm caustic soda solution to dissolve the aluminium. Raney nickel of various grades of activity can be pre­pared by altering the mode of addition of the alloy, the concentration of the alkaline solution, the temperature and time of digestion, and the intensity of the washing process,. These factors were studied in detail by Adkins', who classified the cata­lysts as W-I, W-2, etc., and standardized their activity in terms of the time and temperature for the reduction of \(\beta\)-naphthol to the two tetrahydro derivatives and the yields of the ac and ar isomers. The activity of Raney nickel is increased by adding to the alloy in .portions caustic soda solution instead of the usual reverse procedure ; this catalyst reduces \(cyclo\)hexanone in ethanol to cyclohexanol at 25° and atmospheric pressure in 22 minutes, while the W-7 catalyst requires 40 50 minutes3