Formamidine, from hydrogen cyanide

Formaldoxime, 46,13 reaction with 2-bromo-4-methylben-zenediazonium chloride, 46,14 Formamidine, from hydrogen cyanide, 46,40... 

Formamidines from hydrogen cyanide Cyclic formamidines... 

This method is a modification of the procedure described by Taylor and Ehrhart.2 Formamidine has previously been prepared (as its hydrochloride) from hydrogen cyanide via the formimino ether, which is then treated with ammonia,3 or by desulfurization of thiourea in the presence of ammonium chloride.4 The methosulfate salt of formamidine has been reported to be formed by reaction of formamide with dimethyl sulfate.8... 

The synthesis of various purine bases from hydrogen cyanide as the only carbon-containing substrate was documented by Orgel and coworkers [24]. The only stable precursor found in polymerization of hydrogen cyanide in concentrated (1-llmol/1) aqueous solutions is its tetramer, diaminomaleonitrile. It is easily formed in the reaction of hydrogen cyanide with ammonium cyanide (Figure 8.4). At the same time, in concentrated solutions of ammonium cyanide in the presence of ammonia, formamidine is formed ... 

By contrast, formamidine acetate is not hygroscopic and no particular care need be taken to protect it from atmospheric moisture. Furthermore, formamidine acetate can be used directly without prior treatment with base in syntheses requiring free formamidine.8,7-10 Finally, this preparation of formamidine is by far the simplest and most convenient yet reported it obviates the necessity of using either toxic (hydrogen cyanide) or cumbersome (Raney nickel) reagents, and the method can be adapted to the preparation of N,N -disubstituted formamidines by substitution of primary amines for ammonia.11... 

The reaction product obtained from diphenylcarbodiimide and hydrogen cyanide is an intermediate in Sandmeyers indigo synthesis. HCN can also be eliminated from a-aminocarboxylic acid nitriles 589 to give l-cyano-N,N -disubstituted formamidines 590 and imines 591. ... 

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