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A general electroanalytical method for studying the rate of reaction between an electrogenerated species, e.g. nucleophile, base, electrophile, acid, or radical and an electroactive substrate is described. The method has been used to study the addition of electrogenerated -CH2CN to aromatic carbonyl compounds. The cyanomethyl anion has been generated in two ways, (i) by reduction of azobenzene in acetonitrile, which involves protonation of the dianion by the solvent, and (ii) by reduction of cyanomethyltriphenyl-phosphonium and -arsonium cations in dimethylformamide, which involves reductive cleavage. A computer simulation of the electroanalytical experiments is described and representative results are given, including estimates of the rate constants for the addition of -CH2CN to a series of alkyl phenyl ketones.IN 1974, we reported1 that the electroreduction of aromatic carbonyl compounds (I) in dry acetonitrile gave significant amounts of 3-substituted propiononitriles (IV) and glutaronitriles (V). By analogy with the known reaction of the conjugate base of acetonitrile with carbonyl compounds we suggested that the first step in the formation of these products involves the addition of -CH,CN to the carbonyl group to form a hydroxynitrile (11). The nucleophile might be formed initially via reduction of the carbonyl compound, but sub-

1. The yield and composition of the milk secreted during a 12-day fast is recorded. The solids-not-fat, the nitrogen partition, the chloride, lactose, fat and phosphatase contents are discussed.2. The presence of an unknown substance in the “abnormal” milk obtained from two of the cows is recorded, and it is shown that similar amounts of an unknown constituent must also have existed in the starvation milk analysed in the course of their work by Overman & Wright(i). The nature of this substance has not yet been elucidated.3. Certain substances in the blood were estimated before, during and after the fast, and the possibility of relating changes in them with corresponding changes in the milk is discussed.