Synthesis of urea (carbamide; carbonyldiamide; carbonyldiamine)

Preparation of urea

10 g of ammonium sulfate and 12 g of potassium cyanate are added to 75 ml of water. The solution is evaporated to dryness on water-bath. During the evaporation, a crust of potassium sulfate crystals forms on the surface of the solution. This crust must be repeatedly broken with a glass rod, otherwise the evaporation, becomes extremely slow. It is very important that the evaporation be continued until the solid residue is completely dry. When evaporation is complete the residue is transferred to a 100 ml flask fitted with a reflux condenser. To this flask 40 ml of absolute ethyl alcohol is added, and boiled gently for 5-10 minutes in order to extract the urea. The boiling solution is filtered and the filtrate is cooled in ice-water. Urea separates in colorless crystals, which are filtered and dried yielding 4 g of crystalline product, which melts at 132° C. Additional amount of urea may be obtained by evaporation the ethanolic filtrate and cooling in ice-water. Ammonium sulfate could be replaced with ammonium chloride giving more rapid evaporation procedure as the potassium chloride formed is more soluble in water than potassium sulfate. However, potassium chloride is slightly soluble in ethanol yielding less pure urea.

Practical organic chemistry, by F. G. Mann, 123-124, 1960





InChI Key


Canonical SMILES


MeSH Synonyms

Basodexan, Carbamide, Carmol, Urea

Depositor-Supplied Synonyms

urea, carbamide, Isourea, Carbonyldiamide, Ureophil, Carbonyldiamine, Urevert, Carbamimidic acid, Pseudourea, Ureaphil, 57-13-6, Alphadrate, Aquadrate, Calmurid, Carbaderm, Keratinamin, Pastaron, Urepearl, Carbonyl diamide, Ultra Mide, Carbamide resin, Urea solution, Varioform ii, Aqua Care, Urea-13C, basodexan, carmol, Harnstoff, Supercel 3000, Prespersion, 75 urea, B-I-K, Aqua Care HP, Ureacin-20, Ureacin-10 lotion, Ureacin-40 Creme, Mocovina, Nutraplus, Onychomal, Hyanit, Carbamimic acid, Caswell No. 902, Elaqua xx, Carbonyl Diamine, Mocovina [Czech], Harnstoff [German], Aquacare, Polyurea, Urepeal, Pastaron soft, Urea perhydrate, Bubber shet, Keratinamin Kowa, Aquacare HP, NCI-C02119, Urepeal L, Pastaron 10, Pastaron 20, Pastaron (TN), Pastaron 20 soft, Benural 70, CCRIS 989, Urea ammonium nitrate solution, Carmol 40, HSDB 163, Rubinol ST 010, Optigen 1200, NSC 34375, UR, Carbamide: Carbonyl diamide, EPA Pesticide Chemical Code 085702, diaminomethanone, E927b, AI3-01202, Helicosol, UNII-8W8T17847W, CHEBI:16199, XSQUKJJJFZCRTK-UHFFFAOYSA-N, EINECS 200-315-5, NCGC00090892-01, UREA, ULTRA PURE, Urea-12C, DSSTox_CID_1426, DSSTox_RID_76155, DSSTox_GSID_21426, URE, CAS-57-13-6, aminoketone, diaminomethanae, uree, Isoharnstoff, Superprill, Cerovel, Karbamid, Uroderm, Lotion, amino ketone, amino-ketone, Ureum, Antisepsis bolus, Urea homopolymer, hydroxyformamidine, Urea, homopolymer, beta-I-k, Carbamex 330mgms, carbonamidimidic acid, Ultra Mide 25, Uree 20 Cream, Prespersion 75 urea, Cerovel (Salt/Mix), Panafil (Salt/Mix), Urisec 22% Crm, Dermaflex Crm 10%, Urederm Cream 10%, Urisec Lotion 12%, Urea [JAN], Spectrum_000672, UREA ULTRA PURE, Pylori-chek breath test, Dermal therapy-heel care, UREA, ACS, AC1L1AWB, WLN: ZVZ, Carbamimidic acid (VAN), Spectrum2_001192, Spectrum3_001791, Spectrum4_001168, Spectrum5_001862, Urea (JP15/USP), Urea (JP16/USP), UREA REAGENT GRADE, Urea (8CI,9CI), Dermal therapy-finger care, Eucerin 10% Urea Lotion, Uremol 10 Cream 10%, Uremol 20 Cream 20%, Breathtek ubt for h-pylori, CHEMBL985, Uremol 10 Lotion 10%, AC1Q50ED, H2NC(O)NH2, H2N-C(OH)=NH, UREA, U.S.P., BSPBio_003341, Eucerin Lotion 10% D’uree, KBioGR_001775, KBioSS_001152, KSC269M1N, MLS001076688, DivK1c_000086, H2N-C(=NH)-OH, HO-C(=NH)-NH2, SPECTRUM1500604, U0631_SIGMA, U1250_SIGMA, U4128_SIGMA, U4883_SIGMA, U4884_SIGMA, U5378_SIGMA, U6504_SIGMA, U7129_SIGMA, SPBio_001263, (NH2)2CO, 299367_ALDRICH, 33247_RIEDEL, GTPL4539, U1250_SIAL, U5128_SIAL, Dermaflex 20 Urea Cream 20%, 51456_FLUKA, 51456_SIGMA, 51457_FLUKA, 51457_SIGMA, 51459_FLUKA, 51460_FLUKA, 51465_FLUKA, CHEBI:48376, CTK1G9616, HMDB00294, HMS500E08, KBio1_000086, KBio2_001152, KBio2_003720, KBio2_006288, KBio3_002843, MolPort-000-872-102, NINDS_000086, 33247_SIAL, 51459_SIAL, 51460_SIAL, HMS1921I17, HMS2092C08, HMS2232P21, LTBB002324, Pharmakon1600-01500604, component of Artra Ashy Skin Cream, NSC34375, Tox21_111036, Tox21_202158, Tox21_300035, c0165, CCG-40265, NSC-34375, NSC757375, ZINC08214514, AKOS009031424, 8W8T17847W, DB03904, LS-1389, MCULE-8513891094, NSC-757375, RL04158, RTR-019977, IDI1_000086, Dermal therapy-hand elbow and knee cream, NCGC00090892-02, NCGC00090892-03, NCGC00090892-04, NCGC00090892-05, NCGC00090892-06, NCGC00254181-01, NCGC00259707-01, Simply botanical sensations healing hands, AN-23576, SMR000499585, AB1002498, TR-019977, FT-0645129, FT-0675738, U0073, U0077, C00086, component of Artra Ashy Skin Cream (Salt/Mix), D00023, Murine ear wax removal system/murine ear drops, I14-0449, InChI=1/CH4N2O/c2-1(3)4/h(H4,2,3,4, 6E4EB293-4363-4D38-BF3B-1397372C31E5, 173144-80-4, 173994-65-5, 174693-33-5, 175276-38-7, 30535-50-3, 37955-36-5, 4744-36-9, 860639-56-1

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