Synthesis of barbituric acid

Preparation of barbituric acid

Preparation of barbituric acid

Preparation of barbituric acid

Place 1.2 g of clean sodium metal into a 250 mL round-bottomed flask, fitted with a reflux condenser. Add 25 mL of absolute ethanol in one portion. If the reaction is unduly vigorous, immerse the flask momentarily in ice. When all the sodium has reacted, add 8 g (7,6 mL) of diethyl malonate, followed by a solution of 3 g of dry urea in 25 ml of hot absolute ethanol (70 °C). Shake the mixture well, and reflux it for 1 hour in an oil bath heated to 110 °C. White solid separates. Add 45 mL of hot (50 °C) water to the reaction mixture followed with concentrated hydrochloric acid (ca. 5 mL), with stirring, until the solution is acidic. Filter the resulting mixture and leave clear solution in the refrigerator overnight. Filter the solid on the Büchner funnel, wash it with cold water, drain well and then dry at 100 °C for 2 hours. Weigh the product, calculate the yield of barbituric acid and measure the m.p. (lit. melts with decomposition at 245 °C).   The cyclization reaction and purity of final product could be monitored with thin layer chromatography – ethanol/CH2Cl2 (8:1).

Laboratory of organic chemistry natural products and pharmaceuticals, Anna K. Przybył,  Joanna Kurek, p 16, UAM, Poznań 2013





InChI Key


Canonical SMILES


MeSH Synonyms

barbiturate, barbituric acid, barbituric acid, monosodium salt, sodium barbiturate

Depositor-Supplied Synonyms

BARBITURIC ACID, Malonylurea, 67-52-7, 6-Hydroxyuracil, 2,4,6(1H,3H,5H)-Pyrimidinetrione, Pyrimidinetrione, pyrimidine-2,4,6(1H,3H,5H)-trione, 2,4,6-Trihydroxypyrimidine, Barbitursaeure, Malonylharnstoff, 2,4,6-Pyrimidinetrione, 2,4,6-Trioxohexahydropyrimidine, Hexahydropyrimidine-2,4,6-trione, Hydrouracil, 6-hydroxy-, 1,3-diazinane-2,4,6-trione, Urea, N,N’-(1,3-dioxo-1,3-propanediyl)-, CHEBI:16294, NSC 7889, Barbituric acid (VAN) (8CI), Barbituric acid (VAN), hexahydro-pyrimidine-2,4,6-trione, AC1Q6GAK, EINECS 200-658-0, bmse000346, 1,2,3,4,5,6-Hexahydro-2,4,6-pyrimidinetrione, AI3-02724, AC1L1M19, CHEMBL574699, 11709_FLUKA, CID6211, NSC7889, HNYOPLTXPVRDBG-UHFFFAOYSA-N, 185698_SIAL, AR-1H7693, STK317809, AKOS000288853, LS-7209, 4390-16-3 (mono-hydrochloride salt), C00813, C032232, AC1MMJIY, 32267-40-6, AG-670/31547005, S03-0134, 2,4,6-triketohexahydropyrimidine, 4A0BDFFD-9542-4996-A89F-E5A55D03B250, CHEBI:669285, InChI=1/C4H4N2O3/c7-2-1-3(8)6-4(9)5-2/h1H2,(H2,5,6,7,8,9, CHEBI:29745, 2,4,6-(1H,3H,5H)-Pyrimidinetrione, 1,3,5-trihydropyrimidine-2,4,6-trione, 117491-80-2, 118738-52-6, 1194-23-6, 154254-45-2, 158217-19-7, 160336-60-7, 16564-27-5, 20964-57-2, 223674-02-0, 253678-06-7, 253678-07-8, 253678-08-9, 408335-37-5, 42910-84-9, 465532-08-5, 477705-05-8, 51159-18-3, 53853-41-1, 678184-94-6, 774592-06-2, 860760-03-8, 888733-51-5, 914348-20-2, 944357-77-1, 4,6-dioxo-1H-pyrimidin-2-olate, 2,4,6-trioxotetrahydro-2H-pyrimidin-1-ide, Malonyluree, Pyrimidinetrioe, 6-Hydroxyuracie, BR8, 2,6-Pyrimidinetriol, 6-Hydroxy-Hydrouracie, ACMC-209nzs, 2,4,6-Pyrimidinetrioe, 2,4,6-Trioxypyrimidine, 2,6-Trihydroxypyrimidine, DSSTox_CID_129, Epitope ID:120355, DSSTox_RID_75388, DSSTox_GSID_20129, SCHEMBL38707, 2,6-Trioxohexahydropyrimidine, KSC353A6J, UNII-WQ92Y2793G, DTXSID8020129, CTK2F3064, 2,4,6-Trihydroxy-1,3-diazine, WQ92Y2793G, NSC-7889, ZINC5187769, 2,6(1H,3H,5H)-Pyrimidinetrione, Tox21_200924, ANW-35366, DAP001351, DAP001459, MFCD00006666, SBB004242, STL451498, 2,6-(1H,3H,5H)-Pyrimidinetrione, AKOS024255606, 2,4,6-(1H,3H,5H)pyrimidinetrione, 2,4,6-Pyrimidinetrione(1H,3H,5H), BS-3763, CID3262018, MCULE-3947237773, RP19766, TRA0013476, CAS-67-52-7, 2,4,6-Trihydroxypyrimidine; Malonylurea, 2-hydroxypyrimidine-4,6(1H,5H)-dione, NCGC00248877-01, NCGC00258478-01, AN-23765, HE020658, HE300228, KB-74849, Urea,N’-(1,3-dioxo-1,3-propanediyl)-, 4,6-dihydroxy-2,5-dihydropyrimidin-2-one, AB1000077, ST2413747, TR-022685, B0003, B1063, FT-0622555, ST45058789, 5642-EP2272849A1, 5642-EP2292586A2, 5642-EP2292593A2, 138946-EP2272849A1, 138946-EP2292586A2, A835792, Q-200672, F0001-1773

Removed Synonyms

Pyrimidinetriol, Barbiturate, 2,4,6-Pyrimidinetriol, Sodium barbiturate, barbiturate anion, BALSALAZIDE, Barbituric acid derivative, Barbituric acid, monosodium salt, MolPort-000-998-466, MolPort-035-945-494, RTR-022685, N,N inverted exclamation marka-Malonyluree, N,N inverted exclamation marka-(1,3-dioxo-1,3-propanediyl)urea, 63896-95-7, 65036-65-9

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1 comment


    Sorry sir, after following this method of barbituric acid synthesis ,up to the reflection stage we got solid compound then after as we added water into it converted into liquid and the we added con.HCl to maintain ph up to 5 then after we kept it to freeze, two days latter we found it liquid, Sir please make us clear where we are commiting mistake.

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