General Cyanation Procedure

The Cyanation Reaction. Three examples of the cyanation reaction and the general procedure for the determination of the relative rates are reported below. 

Oxidation of thiocyanate is complicated by the variety of products which may arise, and by rates of reaction which limit the range of analytical procedures which may be used. The results suggest that the first step is analogous to (4). Further reaction of the (unidentified) product leads to sulphate, cyanide, cyanate and sulphur dicyanide. Paths proposed for their formation include intermediate formation of thiocyanogen (reaction (5)), but there are other alternatives. Only in the higher pH region (6-7.6) were the later steps sufficiently fast to produce simple kinetics. The general rate expression is of the form... 

Thiourea (98) was first prepared in 1870 by heating ammonium thiocyanate (99) (Scheme 54). The reaction is analogous to the historic preparation of urea (Wohler, 1828) which involved heating ammonium cyanate. Thioureas generally are stable crystalline solids which are useful in the synthesis of heterocyclic compounds. Symmetrical thioureas (100) may be obtained by the action of amines on carbon disulfide, and the procedure can be extended to the synthesis of cyclic thioureas (101) (Scheme 55). The reaction occurs via the intermediate (102) which on subsequent treatment with either ammonia or an amine yields the corresponding... 

Amide—> Isocyanate. A general procedure for the conversion of amides into acylisocyanates" provides a route to these compounds more convenient than the reaction of acid chlorides with silver cyanate. In the example formulated a mixture of u-chloroucelamide ami 100 ml. of ethylene dichloride is chilled to about 2" and timiH u/hiia D.6 mala of oxalvl uhlorldo li added all at on c. The mixture I removed... 

Bismuth bromide-catalyzed allylation and cyanation of carbonyl compounds and acetals general procedure... 

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