Semicarbazide sulfate

Semicarbazide (Aminourea, Carbamylhydrazine or Hydrazine carboxamide). NHi.NH.CO.NHj mw 75.07 colorl prisms mp 96° d l,484g/cc at 4°. V sol in w sol in ethanol. Prepn is by electrolytic redn of nitrourea in sulfuric acid. The base Is then obtd by reaction of the semicarbazide sulfate with liq ammonia. CA Registry No [57-56-7]. See also in Vol 2, C45-L, under Carbazide for a definition of semicarbazide Semicarbazide forms salts which are either expl or, as in the case of the hydrochloride, are used in propint compns... 

Salts of semicarbazide have been prepared by the action of potassium cyanate on hydrazine sulfate 1 by the action of hydrazine hydrate on urea 2 by heating hydrazine ammonium carbonate 3 bv the reduction of nitrourea with zinc dust and hydrover. 27, 31 (1894). 

Many of the iV-alkyl and iV-aryl derivatives of urazine have been synthesized and characterized, but the parent substance is not well known. In the past, urazine has been prepared by thermal deammonation of carbohydrazide-iV-carboxamide [eq. (I)],1 fusion of hydrazidicarbamide with hydrazinium hydrogen sulfate [eq. (2)],2 fusion of earbohy-drazide with urea [eq. (3)],3 action of sodium hypobromite on semicarbazide [eq. (4)],4 reaction of dichlorourea with concentrated ammonia [eq. (5)],5 and the reaction between 1,2 hydrazine carboxylic ester and hydrazine hydrate... 

Dimethylpyrazole has been prepared from acetylacetone and hydrazine hydrate in ethanol3 or hydrazine sulfate in aqueous alkali.4 6 The latter method is preferred, because the reaction with hydrazine hydrate is sometimes violent.3 4 3,5-Dimethyl-pyrazole has also been prepared by hydrolysis and decarboxylation of the 1-carbamido- or 1-carboxamidine derivatives, obtained by reaction of semicarbazide 7 or aminoguanidine 8 with acetylacetone. 

---