Carbonyl addition cyanide+acetone

Finally, examine transition states for cyanide addition cyanide+formaldehyde, cyanide+acetone, cyanide+ benzophenone) What relationship, if any, is there between the length of the forming CC bond and the various carbonyl properties determined above Try to rationalize what you find, and see if there are other structural variations that can be correlated with carbonyl reactivity. 

Predict the product formed by nucleophilic addition of cyanide ion (CN ) to the carbonyl group of acetone, followed by protonalion to give an alcohol ... 

The potassium cyanide complex of 18-crown-6 in benzene or acetonitrile undergoes Michael addition to unsaturated carbonyl compounds (Liotta et al., 1977). In the presence of acetone cyanohydrin, the catalytic (i.e. catalytic in potassium cyanide and crown ether) cycle for hydrocyanation shown in (21)... 

An alternative procedure, suitable for the preparation of cyanohydrins which readily form bisulphite complexes, is illustrated by the preparation of mandelic acid described in Expt 5.168 (see also the preparation of acetone cyanohydrin). Here the procedure involves the addition of a saturated solution of sodium metabisulphite to a stirred solution of the carbonyl compound and aqueous sodium cyanide, and when applicable is usually to be preferred to the in situ generation of hydrogen cyanide or the use of the highly poisonous liquid hydrogen cyanide as a reagent. 

You met nucleophilic addition to a carbonyl group on p. 114 and 119, where we showed you how cyanide reacts with acetone to give an alcohol. As a reminder, here is the reaction again, with its mechanism. 

The reaction of carbon nucleophiles with the electron-deficient carbon of a carbonyl group represents one of the major ways of making C--C bonds. The addition of hydrogen cyanide to acetone to form the cyanohydrin g 3,15) was one of the first reactions to be studied mechanistically. The reversible reaction leads to the cyanohydrin in which the cyano group may be further modified by hydrolysis to a carboxylic acid or by reduction to an amine. 

The addition of hydrogen to position 4 of the pyridine ring is only one of several addition reactions known. The addition of CN to DPN was reported in 1938, and was later found to be a general reaction of N-substituted nicotinamide compounds. The spectrum of the cyanide addition compound resembles that of DPNH, and the appearance of the cyanide-compound spectrum has been used to assay N-substituted nicotinamide compounds. Acetone and other carbonyl compounds also add to DPN to form similar compounds with similar spectra. It was suggested that the binding of DPN to triose phosphate dehydro-... 

As mentioned already, the use of organic solvents for the HNL-catalyzed addition of HCN to carbonyl compounds was decisive for many investigations concerning optically active cyanohydrins. Several variations for the practical performance of the HNL-c alyzed preparation of (R)- and (S)-cyanohydrms have been developed in recent years. Instead of pure organic solvents, a biphasic system (water/organic solvent) can be used for the reaction whereby HCN can be prepared in situ from sodium cyanide and acetic acid [20] or by transcyanation with acetone cyanohydrin [21]. It is possible to replace isolated enzymes by whole cells, e.g., by almond and apple meal instead of PaHNL or by Sorghum shoots instead of SbHNL [21,22]. 

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