A process for the dissolution of chemical compounds by use of ureas in which at least one of the urea's two nitrogen atoms is part of a non-aromatic ring which can be broken by an oxygen or sulphur atom as a chemical solvent, and a method of producing tri- or tetraalkylated ureas or bis ureas wherein at least one of the urea's nitrogen atoms is part of a non-aromatic ring which can be broken by an oxygen or sulphur atom by means of dialkylating the --NH.sub.2 group of a urea with an alkene or alkene arylene alkene dihalogenide, disulphonate or dihydrogen sulphonate in the presence of a solid base and a phase-transfer catalyst.