C-Cyanation

Predict the bond angles at the central atom of the following triatomic molecules and ions (a) ozone, 03 (b) azide ion, N3 (c) cyanate ion, CNO ... 

A feature of these conpounds is that they tre iso C cyanate precursors, one molecule of triethylamine being lost on heating. They will thus react with conpounds containing active hydrogen as an isocyanate, and in the case of a polymeric product will give rise to arosslinking. (45)... 

C-Cyanation. The reagent is obtained (70%) in two steps from benzotriazole /V-chlorination with 5% NaOCl and reaction with NaCN in MeCN, Phenylacetonitrile gives phenylmalononitrile after lithiation and exposure to 1 -cyanobenzotriazole. 

In another application, iV-acyl-imidazoles react with lithium alnminium hydride at 0 °C to give aldehydes, providing a ronte from the acid oxidation level. In a similar way, 1-cyanoimidazole acts as a mild and efficient N-, S- and C-cyanating agent. 

Fig. 48. Circular dichroism spectra of Cu2Zn2SOD (B) and of its derivative with thiocyanate (C), cyanate (D), azide (E), and cyanide (F). The CD spectrum of the Ile-137 mutant (A) is also shown. Reprinted with permission from Banci, L. Bencini, A. Bertini, I. Luchinat, C. Piccioli, M. Inorg. Chem. 1990,29, 4867. Copyright 1990 American Chemical Society.

The chloroketone reactive sulfhydryl group in the glutamine binding site of carbamyl phosphate synthetase reacts also with cyanate. " However, the inactive cyanate-enzyme complex regains activity upon incubation at alkaline pH. An S-[ C]carbamylcysteine derivative was isolated from the [" C] cyanate-enzyme complex after digestion with Pronase. S-Carbamyl cysteine moves with 22/ = 0.17 in butanol-acetic acid-water (12 3 5, v/v). 

Potassium [ C]cyanate is most easily prepared by oxidation of K CN with KMn04 . Addition of ammonia and amines to K CNO is its main application in carbon-14 synthesis. The ammonolysis of K CNO upon heating with aqueous ammonia is one of the standard procedures for preparing [ C]urea . Upon its reaction with primary or secondary amines, unsymmetrical [ CJureas such as iV-[ C]carbamoyl aspartic acid 108 are obtained (Figure 7.29). Reaction of two equivalents of K CNO with hydrazine produced... 

---