Tetramethylurea

Tetramethylurea is the organic compound with the formula (Me2N)2CO. It is a substituted urea. This colorless liquid is used as an aprotic-polar solvent , especially for aromatic compounds and is used e. g. for Grignard reagents. Tetramethylurea is the organic compound with the formula (Me2N)2CO. It is a substituted urea. This colorless liquid is used as an aprotic-polar solvent , especially for aromatic compounds and is used e. g. for Grignard reagents. The synthesis and properties of tetramethylurea were comprehensively described. The reaction of dimethylamine with phosgene in the presence of e. g. 50 % sodium hydroxide solution and subsequent extraction with 1,2-dichloroethane yields tetramethylurea in 95% yield. The reactions with dimethylcarbamoyl chloride or phosgene are highly exothermic and the removal of the resulting dimethylamine hydrochloride requires some effort. The reaction of diphenylcarbonate with dimethylamine in an autoclave is also effective. Tetramethylurea is formed in the reaction of dimethylcarbamoyl chloride with anhydrous sodium carbonate in a yield of 96.5%. Dimethylcarbamoyl chloride also reacts with excess dimethylamine forming tetramethylurea. Even though the product is contaminated and smelly it may be purified by addition of calcium oxide and subsequent fractional distillation. Tetramethylurea is also formed during the oxidation of tetrakis(dimethylamino)ethylene (TDAE), a very electron-rich alkene and a strong reducing agent, available from tris(dimethylamino)methane by pyrolysis or from chlorotrifluoroethene and dimethylamine. Tetrakis(dimethylamino)ethylene (TDAE) reacts with oxygen in a (2+2) cycloaddition reaction to a 1,2-dioxetane which decomposes to electronically excited tetramethylurea. This returns to the ground state while emitting green light with an emission maximum at 515 nm.