Барбитуровая кислота хч

Химические свойства

cream coloured fine crystalline powder. Odorless. Soluble in water and ether, insoluble in water and alcohol.

Определение

ChEBI: Barbituric acid is a barbiturate, the structure of which is that of perhydropyrimidine substituted at C-2, -4 and -6 by oxo groups. Barbituric acid is the parent compound of barbiturate drugs, although it is not itself pharmacologically active. It has a role as an allergen and a xenobiotic. It is a conjugate acid of a barbiturate, a barbiturate(2-) and a barbiturate(1-).

Подготовка

Barbituric acid is derived By the reaction of diethyl malonate and urea. First put Urea in a reaction tank containing methanol ,heat , reflux , dissolve, then add the dried diethyl malonate and sodium methoxide, the reaction is refluxed at 66-68°C for 4-5h, after distillation to recover methanol, cooling to 40-50°C, add dilute hydrochloric acid to adjust to pH 1-2.Cool to room temperature, throw to obtain crude, wash with distilled water once, dry to get crude , and then purify with water and activated carbon, dry to obtain products. Industrial barbituric acid is white or pink crystalline powder, strongly acidic, more than 98% content, melting point ≥245°C. Material consumption fixed: diethyl malonate 1098kg/t, urea 476kg/t, hydrochloric acid (reagent grade III) 681kg/t, sodium methanol (28%) 369kg/t, methanol 1025kg/t.

Реакции

Barbituric acid with aromatic aldehydes was used in an experimental study, meant to demonstrate the increased efficiency of Knoevenagel condensation reaction for barbituric acid and various aromatic aldehydes on basic alumina, in the absence of organic solvents under microwave irradiation. It may also be used in electrochemical oxidation of iodine, using cyclic voltammetry and controlled-potential coulometry.

Общее описание

Barbituric acid is a useful acid for organic and drug syntheses. Its dihydrate form can be synthesized from barbituric acid via crystallization from aqueous solution. Crystal structure of barbituric acid (in tautomeric form) has been investigated by a three dimensional fourier transform method. Its enol crystal form has been reported to be thermodynamically stable.

Методы очистки

Recrystallise it twice from H2O, then dry it for 2 days at 100o. [Beilstein 24 III/IV 1873.]