Cyanates and Isocyanates

The trinitride, cyanate, and isocyanate ions, the first two of which are known35 to be linear, no doubt have identical electronic structures. 

For a monograph, see Reutov, O.A. Beletskaya, I.P. Kurts, A.L. Ambident Anions Plenum NY, 1983. For a review, see Black, T.H. Org. Prep. Proced. Int., 1989, 21, 179. Both cyanates and isocyanates have been isolated in treatment of secondary alkyl iodides with NCO Holm, A. Wentrup, C. Acta Chem. Scand., 1966, 20, 2123. 

The differences in structural parameters originating from different techniques and referring to different states have been mentioned in a similar review on cyanates and isocyanates. A more detailed discussion can be found elsewhere" . 

The structures of lithium and sodium cyanates and isocyanates and their related ion-pair 5n2 reactions have been examined by using quantum mechanics at the Hartree-Fock (HF)/6-31G V/HF/6-31G level. (The cyanate ion is NCO the isocyanate ion is CNO. ) The isocyanate ion pairs are the most stable monomeric forms the lowest energy dimers are planar eight-membered rings. For the ionic 5 n2 reaction of cyanate ion with MeF or MeCl, methyl isocyanate is the predicted major product. Predictions about the 5ivr2 reactions of the ion pairs were also made. 

Both cyanates and isocyanates have been isolated in treatment of secondary alkyl iodides with NCO Holm Wentrup Acta Chem. Scand. 1966, 20, 2123. 

The anhydrous acid is obtainable by pyrolysis of the trimer, to which it may revert violently above 0°C. Only one acid is obtainable from both cyanates and isocyanates. 

Under VI we find that hydrogen chloride does add reversibly and stoichiometrically to hydrocyanic acid, but not to give pentavalent nitrogen. It forms amino-formyl chloride, H2C(C1) NH. This substance would undoubtedly add hydrogen chloride to the nitrogen if it did not polymerize. The polymerization products of the nitriles, isonitriles, cyanates and isocyanates have not been studied with any satisfactory degree of care. 

As the bonding arrangement of cyanate and isocyanate groups to tellurium is not known (see p. 617), diorgano tellurium halide cyanates, isocyanates, thiocyanates, and isothiocyanates are treated together on the basis of formal tellurium-nitrogen bonding. 

The principle of Wohler s method provides a method of very wide and varied applicability for the preparation of urea derivatives. Alkali cyanates and isocyanic and isothiocyanic esters on the one hand and ammonia, amines, amides, hydrazines, etc., on the other, undergo the reaction. When an alkali cyanate is used it is usually possible to work in aqueous solution and add the amine as a salt alternatively, the free amine can be used in dilute acetic acid room temperature or moderate temperatures usually suffice. A series of examples for the preparation of monoarylureas by this method is to be found in Organic Syntheses.64... 

Smokers, 61 subjects (35M) whose serum cobalamin concentrations are significantly lower than those of non-smokers. Organic nitrites, nitric oxide, cyanates and isocyanates inhaled with cigarette smoke interact with vitamin B12, neutralizing it. 

H Chemical Shifts (6 in ppm relative to TMS) and Coupling Constants (J in Hz) in Nitriles Isonitrilesy Cyanates and Isocyanates... 

Isothiocyanates (formerly known as mustard oils, 8-136) are compounds with a cumulated system of double bonds belonging to the heterocumulenes, compounds that are formally derived from the hydrocarbon allene (H2C=C=CH2). In small quantities, isothiocyanates are often accompanied by isomeric thiocyanates. Related cyanates and isocyanates do not occur in foods. 

The sulfur analogs of both cyanates and isocyanates are thermally and hydrolytically more stable than the oxygen analogs. Both series of sulfur analogs have been known for some time from natural and synthetic sources. 

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