The Preparation Method of Centralite-II

1,3-Dimethyl-1,3-diphenylurea also known as centralite-II for Stabilizer and propellant, and production of intermediates of organic chemicals. 

Description

Centralite I (N,N'-diethyldiphenylurea), also known as Ethyl Centralite, is white powder or flake, insoluble in water, but soluble in most organic solvents such as acetone, ethanol and benzene. Centralite l is mainly used as a burning rate moderator and stabilizer for smokeless powder, and also a plasticizer for celluloid,especially as a stabilizer in propellants and explosives. Centralite-II (N.N'-Dimethyldiphenylurea), also known as Methyl Centralite , is white or light yellowish flake crystal, soluble in alcohol, ether and benzene, insoluble in water. It is a melted material, which is transparent liquid free from scum. Centralite-II is used for manufacturing ammunition and propellant powders.

Preparation

A 10 mL Schlenk tube equipped with a magnetic stirring bar was charged with arylcarbamoyl chlorides (0.2 mmol, 1.0 equiv), and KHCO3 (40 mg, 0.4 mmol), and then Pd(PPh3)4 (0.01 mmol, 11.56 mg) were added. Finally, 1,4-dioxane (1.0 mL) was added to the mixture via syringe at room temperature under N2. The tube was sealed and put into a preheated oil bath a 100 °C for 48 h. The mixture was cooled to room temperature, quenched with water (5 mL), and diluted with ethyl acetate (5 mL). The layers were separated, and the aqueous layer was extracted with 2 × 5 mL of ethyl acetate. The combined organic extracts were dried over anhydrous sodium sulfate, filtered, and concentrated in vacuo. The crude product of centralite-II was then purified by flash chromatography on silica gel (H), eluting with 30-35% ethylacetate/petroleum ether.