Semicarbazide.hydrochloride

To isolate the semicarbazide hydrochloride, the filtered reaction mixture is treated with excess of acetone and the resulting acetone semicarbazone is decomposed with concentrated hydrochloric acid. 

To decompose the acetone semicarbazone, warm 58 g. with 50 ml. of concentrated hydrochloric acid until it just dissolves. Cool in ice the semicarbazide hydrochloride separates as a thick crystalline mass. Filter at the pump through a sintered glass funnel, and wash with a small quantity of alcohol and then with ether dry in the air. The yield of pure semicarbazide hydrochloride, m.p. 173° (decomp.), is 35 g. A further quantity of product may be obtained either by saturating the mother liquor with hydrogen chloride or by treating it with twice its volume of alcohol and then with ether. 

Diphenylcarbazido is prepared by heating a mixture of phenylhydrazine and urea at 155°  

Hydrazine sulphate reacts with sodium cyanate in the presence of sodium carbonate to giro semicarbazide, which remains in solution  

2NHjNHj,HjSO + Na CO, (NHjNHj)jHjSO + Na SO + H CO, (NHgNHjlaHijSO, + 2NaCNO — 2HjNCONHNHj + NaaSO  

Small amounts of the insoluble hydrazodicarbonamido m.ay also be formed HjNCONHNH, + HCNO —s- HjNCONHNHCONH, 

Small amounts of the insoluble hydrazodicarbonamide may also be formed  

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Required Semicarbazide hydrochloride, i g. anhydrous sodium acetate, 0-9 g. acetophenone, i ml. 

Add first I g. of powdered semicarbazide hydrochloride and then 0 9 g. of anhydrous sodium acetate (or 1-25 g. of the crystalline acetate) to 5 ml. of water, and warm gently until a clear solution is obtained. Then add a solution of i ml. (i g.) of acetophenone in 5 ml. of rectified spirit, and warm the mixed solutions gently on a water-bath for... 

A) Semicarbazones. Prepared according to the directions given for acetophenone semicarbazone (p. 258), but use twice the amount of semicarbazide hydrochloride and sodium acetate. (M.ps., p. 549.)... 

Semicarbazones. Dissolve 1 g. of semicarbazide hydrochloride and 1 5g. of crystallised sodium acetate in 8-10 ml. of water add 0 - 5-1 g. of the aldehyde or ketone and shake. If the mixture is turbid, add alcohol (acetone-free) or water until a clear solution is obtained shake the mixture for a few minutes and allow to stand. Usually the semicarbazone crystallises from the cold solution on standing, the time varying from a few minutes to several hours. The reaction may be accelerated,... 

Semicarbazide hydrochloride (hydrazine carboxamide hydrochloride) [563-41-7] M 111.5, m 173 (dec), 175 (dec), pK " 3.66. Crystd from aqueous 75% EtOH and dried under vacuum over CaS04. Also crystd from a mixture of 3.6 mole % MeOH and 6.4 mole % of water. [Kovach et al. J Am Chem Soc 107 7360 1985.] IR v 700, 3500 cm" [Org Synth Coll Vol I 485 I94I-, Davison and Christie J Chem Soc 3389 I955 -, Thiele and Stange Chem Ber 27 33 I894 pK Bartlett J Am Chem Soc 54 2853 1923]. The free base crystd as prisms from abs EtOH, m 96° [ Curtius and Heidenreich Chem Ber 21 55 1894]. TOXIC ORALLY, possible CARCINOGEN and TERATOGEN. 

Semicarbazide hydrochloride is also useful for the preparation of A -3-ke-tones. °°... 

Semicarbazide hydrochloride [705] and amidrazones [106] react with trifluo-ropyruvates to give six-membered heterocycles A variety of trifliioromethyl substituted heterocyclic systems is available, starting from the hydrate of trifluoropy-ruvicacid, a versatile 1,2-bielectrophihc building block (reaction type 2, equation 10) [107] (equation 24). 

The pH was adjusted to 3.3 with triethylamine and semicarbazide hydrochloride (9.5g) added. The mixture was brought back to pH 3 with further triethylamine, then stirred for 30 minutes at pH 3. The resultant mixture was adjusted slowly over 4 hours to pH 6.8 by addition of triethyl amine, seeding being carried out when pH 4.5 was reached. The precipitated cephalexin was filtered off, washed with dimethylformamide (200 ml) and the cephalexin recovered, yield 75%,... 

Preparation of 3,20-Disemicarbazone of 9a-Fluoro-110,17a,21-Trihydroxy-16a-Methyl-l,4-Pregnadiene-3,20-Dione A mixture of 1.00 gram of 9o-fluoro-11(3,17o,21 trihydroxy 16o methyl 1,4 pregnadiene 3,20 dione, 750 mg of semicarbazide base, 280 mg of semicarbazide hydrochloride in 20 ml of methanol and 10 ml of dimethylformamide is refluxed for 20 hours under nitrogen. The mixture Is cooled to 20°C and 100 ml of water Is added with stirring. The precipitated 3,20-disemicarbazone of 9o -fluoro-11(3,17o, 21-trihydroxy-16o -methyl-1,4-pregnadiene-3,20-dione Is filtered, washed with water, and dried in air MP over 300°C. 

C ( propyl) N phenylmtrone to N phenylmaleimide, 46, 96 semicarbazide hydrochloride to ami noacetone hydiochlonde, 46,1 tetraphenylcyclopentadienone to diphenyl acetylene, 46, 44 Alcohols, synthesis of equatorial, 47, 19 Aldehydes, aromatic, synthesis of, 47, 1 /3-chloro a,0 unsaturated, from ke tones and dimethylformamide-phosphorus oxy chloride, 46, 20 from alky 1 halides, 47, 97 from oxidation of alcohols with dimethyl sulfoxide, dicyclohexyl carbodumide, and pyndimum tnfluoroacetate, 47, 27 Alkylation, of 2 carbomethoxycyclo pentanone with benzyl chloride 45,7... 

Methylcyclopentane-1,3,5-tnone, reaction with semicarbazide hydrochloride, 47, 84... 

Reaction of 1 with semicarbazide hydrochloride gives the semicarbazone 4, in 74 % yield, which can be oxidized by selenium(IV) oxide to provide dibenzo[2,3 6,7]thiepino[4,5-rf][l,2,3]selenadi-azole (5) in 80 % yield. Thermolysis of selenadiazole 5 leads, with subsequent release of nitrogen, to diradical 6, which can either dimerize to 7 or lose selenium to give the intermediate cycloalkyne. The latter can be trapped by dienes as cycloadducts.93 Thus, the thermolysis of 5 in the presence of 2,3,4,5-tetraphenylcyclopenta-2,4-dienone gives the cycloadduct 1,2,3,4-tetraphenyltribenzo-[/ ,<7,/]thiepin (8) in 14% yield. 

CH5N30 57-56-7) see Azimilide hydrochloride Carbazochrome Cortisone Fluazacoit Trazodone semicarbazide hydrochloride (CHftCIN O 563-41-7) see Desoximetasone Hydrocortisone Nitrofural semicarbazidoacetic acid (C3H7N3O3 138-07-8) see Nitrofurantoin D-serine... 

Prepare a solution of 1-0 g. of semicarbazide hydrochloride (NHjCONHNHj.HCl) and 1 - 5 g. of crystallised sodium acetate in 10 ml. of water in a test-tube. Add 1 ml. of acetone, close the tube with a cork and shake vigorously. Allow the mixtm e to stand, with occasional vigorous shaking, for 10 minutes it is advantageous to cool in ice. Filter the crystals, wash with a little cold water, and recrystallise from water or dilute alcohol. The m.p. of acetone semicarbazone is 187°. 

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