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Your Location:Home > Synthesis of Thiourea

1. Introduction

Thiourea in the petrochemical, pharmaceutical and chemical also has pan of applications, many drug molecules are also structural fragment thiourea. For example, currently on the market a lot of oral hypoglycemic agents, anti-thyroid drugs belong thiourea molecules. Chemical thiourea are usually some of the following methods.

2. isothiocyanate reacts with the amine thiourea

To a solution of tert-butylisothiocyanate (5.0 mL, 39 mmol) in dichloromethane (200 mL) were added isopropylamine (4.0 mL, 47 mmol) and diisopropylethylamine (DIEA) (6.8 mL, 39 mmol), and the mixture was stirred at rt for 2h. The reaction mixture was diluted with EtOAc, washed with 10 percent citric acid (2x), saturated NaHCO3 (2x), H20 (2x), and brine (1x). The organic layer was dried (MgS04) and evaporated to the crude product, which was purified by column to afford 1-tert-butyl-3-isopropyl-thiourea (3.3 g, 52%).

3. thiophosgene with an amine to generate thiourea

To a solution of 8.5 g of 3-chloro-5-fluoroaniline in 150 ml of benzene was added a solution of 2.2 g of thiophosgene in 10 ml of benzene dropwise at room temperature under nitrogen. The resulting mixture was stirred at 60 oC for 3 hours and then cooled to room temperature. After filtered, the filtrate was concentrated to the oil, which was followed by a solution of t-pentylamine (3.4 g) in 30 ml of benzene. The mixture was stirred at room temperature for another 30 minutes . The reaction mixture was evaporated in vacuo and the resulting solid recrystallized from cyclohexane to give 2.2 g of the title compound as colorless needles 1- (3-chloro-5-fluoro-phenyl) -3- (2,2-dimethyl-propyl ) -thiourea

4. thiocarbonyl diimidazole reacts with an amine thiourea

To a mixture of 1,1'-thiocarbonyldiimidazole (535 mg) and acetonitrile (7 ml) was added a solution of 3- (N, N-Dimethyl) aniline (272 mg) in acetonitrile (7 ml) dropwise over period of 15 minutes at 0oC under nitrogen. After stirring for 2 hours at ambient temperature, 2- (aminomethyl) pyridine (433 mg) was added to the mixture. The reaction mixture was then heated to 60 oC for 4 hours. After cooling to room remperature, the reaction mixture was evaporated to the residue, which was purified by column (DCM / MeOH) to give 1- (3-Dimethylamino-phenyl) -3-pyridin-2- ylmethyl-thiourea (423 mg).

5. Use thio chloromethylbenzene ester thiourea

A mixture of n- Bu2NH and [4- (4-ethyl-phenylamino) -phenyl] -thiocarbamic acid O-phenyl ester (348) in ethanol was heated to reflux under N2 atmosphere for 16 h. After removal of the solvent, the residue was dissolved in DCM. The organic phase was washed with 1 N of sodium hydroxide (3 x 50 mL), 1 N of HCl aqueous solution and brine (5 X 50 mL). After dried over anhydrous Na2SO4 and filtered, the filtrate was concentrated to give

the crude product, which was purified by column to afford 1,1-dibutyl-3- [4- (4-ethyl-phenylamino) -phenyl] -thiourea

6. thiocarboxamide mercapto carbonyl thiourea

A mixture of 4-methyl-pyrimidin-2-ylamine (2.2 g, 20 mmol) and pyridin-2-yl-dithiocarbamic acid methyl ester (3.6 g, 20 mmol) in 100 mL of toluene was heated to reflux for 10 h. After removal of the solvent, the residue was recrystallized from methanol to afford 3.4

g of 1- (4-methyl-pyrimidin-2-yl) -3-pyridin-2-yl-thiourea.

7. thio reagent (e.g. Lawsson reagent) obtained by reacting thiourea and urea

To 4.0 g of 1- (2,4-di-tert-butyl-3-hydroxy-phenyl) -3- (4-nitro-benzyl) -urea was added 6.0 g of a lawson reagent dissolved in 50 mL of 1, 4-dioxane at room temperature under N2

atmosphere. The resulting mixture was heated to reflux for 15 h before poured into 150 mL of water. The mixture was extracted with ethyl acetate (3 x 100 mL). The combined organic phases were washed with brine, dried over anhydrous sodium sulfate and filtered . The filtrate was concentrated to the crude product, which was purified by a silica gel column to give 2.5 g of 1- (2,4-Di-tert-butyl-3-hydroxy-phenyl) -3- (4-nitro- benzyl) -thiourea (60%)

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