Silver isocyanate synthesis

See also Silicon tetraisocyanate and methylsilicon isocyanates (includes silver isocyanate), synthesis 6... 

The synthesis from silver isocyanate and phosphorus(III) chloride has proved the most dependable and gives the highest... 

This reaction is a consequent continuation of an already described lactone synthesis where (3- or 7-halo-esters were treated with silver isocyanate to form the corresponding P- or 7-lactone (Scheme 75). Via this method TMS P-bromo-propionate 500) affords P-propiolactone 464 ... 

Isocyanate synthesis. A convenient and general method for isocyanate synthesis is by oxidation of oxalylamines. Silver nitrate and copper(II) sulfate are cocatalysts. 

Treatment of alkyl halides with alkali metal or silver cyanate is of no preparative value for the synthesis of cyanates. - - As cyanate ions do represent ambident nucleophiles. Holm and Wentrap tried to reach cyanates under well-defined SnI conditions (Scheme 28). But even treatment of isopropyl iodide with silver cyanate in nitromethane provided only a very low yield of a 1 1 mixture of isopropyl cyanate and the corresponding isocyanate, and from a reaction of silver cyanate with triphenylchloro-methane they isolated only triphenylmethyl isocyanate, although the cyanate may have been an intermediate in this transformation." ... 

From a practical point of view, isocyanates, together with carbamates and ureas (Chapter 3), are the most important organic products discussed in this book. Their synthesis from nitroarenes has indeed been the subject of many patents. There are also limited examples of aliphatic isocyanates obtained by this route. Organic mono- and diisocyanates may be prepared in a continues liquid phase method by treating the appropriate amine with phosgene. However, the reaction is rather complex [6] and, besides the use of the dangerous phosgene, the formation of the corrosive hydrochloric acid creates several problems. Aliphatic isocyanates can also be obtained from olefins with isocyanate ion in the presence of a salt of a coordination compound of palladium or platinum [7], from olefins with isocyanic acid in the vapour phase over Pt/ALOs [8], and from formamides, by oxidation over a silver catalyst [9]. Apparently only the last reaction seems to have some potential practical applications [10]. 

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