Synthesis of thiosemicarbazide

Preparation of thiosemicarbazide

Preparation of thiosemicarbazide from hydrazine hydrate

Preparation of thiosemicarbazide from hydrazine hydrate

Preparation of thiosemicarbazide from hydrazine hydrate

200 g of ammonium thiocyanate are dissolved in a solution containing 59 ml of 85% hydrazine hydrate and 25 ml of water. The obtained mixture is refluxed for three hours under a nitrogen atmosphere, then allowed to cool slightly and filtered in order to remove the coagulated sulfur. Then the filtrate is left to stand overnight, the obtained crystals are filtered and recrystallized from a mixture of water-ethanol (1:1) yielding 46 g of thiosemicarbazide, with melting point 180-182° C. Evaporation of the mother liquor gives an additional 5 g of product and total yield of thiosemicarbazide is 56.6%.

J. Org. Chem., 19 (5), 749–752, (1954);

Preparation of thiosemicarbazide from hydrazine sulfate


Preparation of thiosemicarbazide

Preparation of thiosemicarbazide from hydrazine sulfate

A solution of 27.5 ml of concentrated sulfuric acid (0.5 mol) in 500 ml of water is added slowly, with stirring, to a solution of 59 g of 85% hydrazine hydrate (1 mol) in 500 of water in a 2-l beaker. A solution of 145 g of barium thiocyanate 2-hydrate (0.5 mol) in 500 ml of water is added to the solution of hydrazinium sulfate. The barium sulfate precipitate is stirred thoroughly and is then digested on a steam bath for 2 hours or more before filtering. For quick removal of the barium sulfate precipitate, the slurry is filtered by suction through a mat of filter-paper pulp between two pieces of filter paper, using a large Buchner funnel. The clear, or only slightly cloudy, filtrate is then evaporated until the total volume has been reduced to about 200 ml. At this point it may be necessary to filter the solution again. The clear solution is then transferred to a round-bottomed flask fitted with a thermometer well. The solution is boiled until its temperature reaches 110° C. A reflux condenser is then attached to the flask, and the solution is maintained at the boiling point for 30 minutes. Upon cooling, a mass of crystals separates; these are removed by filtration. The filtrate is returned to the flask, and the refluxing at 100° C is repeated. Five fractions of crystals are obtained from the solution in this manner. The crude thiosemicarbazide is purified by recrystallization from 50% ethanol. The yield of recrystallized material varies from 40 to 50% of theory, depending on the completeness of the conversion of the salt to the final reaction product.

Inorganic Syntheses, Vol. 4, 1953, 39-41.





InChI Key


Canonical SMILES


MeSH Synonyms

N-aminothiourea, thiocarbamylhydrazine, thiosemicarbazide, thiosemicarbazide hydrochloride, thiosemicarbazide monohydrochloride

Depositor-Supplied Synonyms

Thiosemicarbazide, Hydrazinecarbothioamide, 79-19-6, N-Aminothiourea, aminothiourea, 1-Aminothiourea, Semicarbazide, thio-, Isothiosemicarbazide, 2-Thiosemicarbazide, Thiocarbamoylhydrazine, Semicarbazide, 3-thio-, 3-Thiosemicarbazide, Thiocarbamylhydrazine, 1-AMINO-2-THIOUREA, USAF EK-1275, Aminothio-urea, RCRA waste number P116, Thiocarbamoyl hydrazide, NSC 2213, Isothiosemicarbazide (VAN), RCRA waste no. P116, CCRIS 1416, CHEMBL256250, TSZ, HSDB 6050, BRWIZMBXBAOCCF-UHFFFAOYSA-N, EINECS 201-184-7, SBB040860, WLN: ZMYZUS, AI3-16319, DSSTox_CID_1346, DSSTox_RID_76099, DSSTox_GSID_21346, aminohydrazinomethane-1-thione, CAS-79-19-6, 1-azanylthiourea, thiosernicarbazide, thio-semicarbazide, THIOSEMICARBAZINE, PubChem13594, ACMC-1BJCC, AC1MC3LX, (aminothioxomethyl)hydrazine, (aminothioxomethyl)-hydrazine, T33405_ALDRICH, KSC377I9J, UNII-6056O8W6ET, 89050_FLUKA, 89051_FLUKA, Carbamohydrazonothioicacid (9CI), CTK1D8582, CTK2H7494, NSC2213, MolPort-000-872-021, 6056O8W6ET, AC1Q5513, NSC-2213, NSC31792, 4346-94-5 (mono-hydrochloride), Tox21_201348, Tox21_302983, ANW-37266, NSC-31792, AKOS000269047, LS-2185, MCULE-6378380063, RP18554, RTR-025228, TRA0052184, NCGC00091884-01, NCGC00091884-02, NCGC00256506-01, NCGC00258900-01, AK-40145, AN-23981, BR-40145, KB-61713, SC-18209, DB-030119, TR-025228, AM20100785, FT-0657078, FT-0695329, ST50214450, A839613, 3B3-034716, 4426-73-7

Removed Synonyms

Thioridazine hydrochloride, CID2723789, T0221, TSC, 130-61-0

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