Cyanates, alkali metal

Carbamyl and thiocarbamyl fluorides are obtained from hydrogen fluoride and cyanic acid or alkali metal cyanates or thiocyanates [/, 54] Nitnles give iraidofluoride salts with hydrogen fluoride [7] whereas hydrogen cyanide affords difluoromethylamine, which can be isolated as its hexafluoroarsinate salt [55) (equation II)... 

Alkali metal cyanates are stable and readily obtained by mild oxidation of aqueous cyanide solutions using oxides of or Ptf. The commercial preparation of NaNCO is by reaction of urea with Na2C03. 

N-Arylureas are obtained when salts of primary aromatic amines react with solutions of alkali metal cyanates. The process involves the rearrangement of an amine cyanate, and is analogous to Wohlers classical synthesis of urea from ammonium cyanate. 

Alkali metal azides, 1 79 2 139 Alkali metal cyanates, 2 86 Alkali metal pyrosulfites, 2 162 Alkali metal sulfites, 2 162 Alkaline earth azides, 1 79 Allanite, extraction of, 2 44 Allophanyl azide, formation of, from allophanyl hydrazide, 5 51 Allophanyl hydrazide (1-amino-biuret), 5 48 hydrazones of, 5 51 from methyl and ethyl alloph-anates, 5 50 salts of, 5 51... 

The Lattice Energies (kcal/mole) of the Alkali Metal Cyanates... 

Phosphorus isocyanate, P(NCO)3, mp = -2°C, is obtainable from reaction (6.637), or from PCI3 and an alkali metal cyanate. On standing, it slowly changes to the cyanate, but on distillation it reverts to the isocyanate... 

Other isocyanate syntheses that have recently been reported include several well-known reactions. One area which has attracted considerable attention is that of the direct production of isocyanates by the carbonylation of nitro-arenes. Both mono- and di-isocyanates are claimed to have been produced using various catalysts palladium, rhodium, and iron compounds often being cited. Other preparative reactions for isocyanates which have appeared in the literature include the acid catalysed hydrolysis of isocyanide dihalides and the reaction between alkyl halides and alkali-metal cyanates, although the latter has been given a modern flavour by the use of a polymer-supported reagent. ... 

Synthesis.— The preparation of a-amino-acids from a-halogeno-acids and ammonia is often unsatisfactory owing to the occurrence of multiple alkylations etc. A way around this problem is to treat a-halogeno-esters with alkali-metal cyanates and an alcohol this gives N-alkoxycarbonyl-a-amino-esters in >90% yield. " The O-arylhydroxylamine (148) is a useful reagent for aminating enolates, especially those derived from malonic esters, which can thus be... 

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