GB940381A - Preparation of dialkyl sulphoxides - Google Patents

Abstract

Dialkyl sulphoxides are prepared by mixing a solution of an alkyl aluminium compound in an inert organic solvent with a solution of thionyl chloride in an inert organic solvent under an atmosphere of an inert gas while maintaining throughout the addition a temperature of from -25 DEG to 100 DEG C. and then maintaining the mixture at a temperature of from 0 DEG C. to 100 DEG C. until the thionyl chloride and alkyl aluminium compound have reacted, hydrolyzing the reaction mixture with simultaneous or subsequent cooling to maintain it below 100 DEG C. and then recovering the dialkyl sulphoxide. The alkyl aluminium reactant may be a compound having the general formula R3Al, R2Al OR or R2Al Cl wherein R is an alkyl group. The solvents may be hydrocarbons or ethers. The mixing is preferably effected at 0 DEG -30 DEG C. and the mixture is thereafter preferably maintained at 30 DEG -80 DEG C. In examples: (1) di-n-octyl sulphoxide is prepared from tri-n-octyl aluminium; triethyl, tri propyl, tri butyl and tri dodecyl aluminiums may also be used to form the corresponding dialkyl sulphoxides; (2) dihexyl sulphoxide is prepared from dihexyl aluminium hexoxide or chloride. The sulphoxides may be used as oxidation inhibitors in lubricating oils or in diesel fuel to raise the cetane number.ALSO:Diesel fuels comprise dialkyl sulphoxides as cetane number improvers. Specified sulphoxides are di-ethyl, -propyl, -butyl, -hexyl, -n-octyl and dodecyl sulphoxides.