Chemical Properties
Off-White to Yellow Powder
Uses
4,6-Dihydroxy-2-mercaptopyrimidine can be used to quantitate lipopolysaccharides, carrageenan, and sialic acids, and to detect lipid hydroperoxides and lipid oxidation.
Definition
ChEBI: A barbiturate, the structure of which is that of barbituric acid in which the oxygen at C-2 is replaced by sulfur.
Preparation
2-thiobarbituric acid was synthesized by the reaction of diethyl malonate with thiourea. Dissolve thiourea in methanol, add sodium methoxide and diethyl malonate, heat under reflux for 4-5h, then distill under reduced pressure to recover methanol to the end, and add hydrochloric acid to acidify to pH 1-2 after cooling. After standing overnight, thiobarbituric acid crystals were precipitated, filtered, and recrystallized with water to obtain the pure product.
General Description
2-Thiobarbituric acid is a molecule made up of heteroatoms: nitrogen, sulphur and oxygen.
Biochem/physiol Actions
2-Thiobarbituric acid (TBA) is useful to quantitate lipopolysaccharides, carrageenan, and sialic acids. It is also used to detect lipid hydroperoxides and lipid oxidation. It has applications in the field of medicine and biochemistry. TBA may possess the ability to prevent metal corrosion.
Synthesis
The general procedure for the synthesis of 4,6-dihydroxy-2-mercaptopyrimidine from the compound (CAS: 17356-08-0) and diethyl malonate was as follows: 6 g (0.25 mol) of sodium metal was dissolved in 200 mL of anhydrous ethanol. Subsequently, 15 g (0.25 mol) of thiourea and 40 mL of diethyl malonate were sequentially added to this solution. The reaction mixture was placed in an oil bath and refluxed for 6 hours. Upon completion of the reaction, ethanol was recovered by vacuum distillation. The clarified solution obtained was washed with water and then cooled in an ice bath overnight. After cooling, the solution was acidified with hydrochloric acid (HCl). The crude product precipitated after acidification was collected, washed with 50 mL of water and dried in an oven at 105°C-110°C for about 4 hours. Finally, thiobarbituric acid (TBA) was purified by ethanol recrystallization to give a melting point of about 243°C and a yield of about 80%.
Purification Methods
Crystallise it from water. [Beilstein 24 H 476, 24 I 414, 24 II 275, 24 III/IV 1884.]
References
[1] Oriental Journal of Chemistry, 2017, vol. 33, # 1, p. 304 - 317
[2] Medicinal Chemistry Research, 2013, vol. 22, # 9, p. 4075 - 4086
[3] Chemistry of Natural Compounds, 2001, vol. 37, # 6, p. 543 - 550
[4] Journal of Medicinal Chemistry, 2007, vol. 50, # 8, p. 1778 - 1786
[5] Bioorganic and Medicinal Chemistry Letters, 2007, vol. 17, # 14, p. 3953 - 3956
