Reaction Addition of Hydrocyanic Acid to an Aldehyde

Example Mandelic Add from Benzaldehyde1 (a) Mandelic Nitrile 

In a flask containing 13 grammes of finely pulverised 100% potassium cyanide, or an equivalent amount of the purest salt 

Much better results are obtained by preparing mandelic nitrile1 thus Pour 50 c.c. of a concentrated solution of sodium bisulphite over 15 grammes of benzaldehyde in a beaker stir the mixture 

The nitrile is mixed with four times its volume of concentrated hydrochloric acid in a porcelain dish, and evaporated on the water-bath until crystals begin to separate out on the upper surface of the liquid. 

The reaction-mixture is then allowed to stand over night in a cool place the crystals separating out, are triturated with a little water, filtered off with suction, and then washed with not too much water. A further quantity of the acid may be obtained by 

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