Dimethylbarbituric acid

Uses1,3-Dimethylbarbituric acid is used as a catalyst in the Knoevenagel condensation of a series of aromatic aldehydes. It is also used in the synthesis of 5-aryl-6-(alkyl- or aryl-amino)-1,3-dimethylfuro [2,3-d]pyrimidine derivatives and enantioselective synthesis of isochromene pyrimidinedione derivatives.

Uses1,3-Dimethyl Barbituric Acid (Urapidil Impurity 4) is a derivative of Barbituric acid. All of the barbituric acid derivatives which have been reported to have pronounced hypnotic activity are disubstituted in the 5-position.

General Description1,3-Dimethylbarbituric acid (1,3-Dimethyl-2,4,6(1H,3H,5H)-pyrimidinetrione) is an active methylene compound. It undergoes hollow Pd6 water-soluble cage, [{(tmen)Pd}6(timb)4](NO3)12 (tmen= N,N,N′,N′-tetramethylethylenediamine, timb=1,3,5-tris(1-imidazolyl)benzene)-catalyzed Knoevenagel condensation reaction with pyrene-1-carboxaldehyde. It undergoes self-sorted Pd7 molecular boat having an internal nanocavity (catalyst)-assisted Knoevenagel condensation reaction with various aromatic aldehydes. It has been synthesized by reacting 1,3-dimethylurea, malonic acid and acetic anhydride in acetic acid. It is widely used for the synthesis of various synthetic intermediates and heterocyclic compounds.

Preparation1.1 mol of dimethyl malonate and 1.0 mol of 1,3-dimethylurea were added to a reactor, along with 900 g of n-butanol solvent, 900 g of toluene, and 58 g of sodium ethoxide catalyst. The mixture was stirred and heated to 90–110 °C, then refluxed for 10 hours. After the reaction was complete, the reactants were cooled, and a solid precipitated. The solid was dissolved in water, and the pH was adjusted to 1–2 with hydrochloric acid. After cooling, crystals precipitated, and the crude product was filtered to obtain 132 g. Recrystallization yielded 119 g of 1,3-dimethylbarbituric acid with a melting point of 121.4–123.2 °C, a yield of 76%, and a purity of 99.7%.