GB828821A - Low temperature sulfonation process - Google Patents

Abstract

Oil-soluble sulphonates are prepared by contacting a solution of a petroleum hydrocarbon oil in liquid sulphur dioxide at a temperature not exceeding 0 DEG C. with a sulphonating agent in a single treating step, removing the sulphur dioxide, neutralizing the resulting mixture in the presence of a hydrophilic solvent, and countercurrently extracting the total product emulsion at a temperature above 50 DEG C. with an organic solvent to produce an extract phase containing oil-soluble sulphonates of high quality. The sulphonating agents include 100% sulphuric acid, oleum and stabilized liquid anhydrous SO3, 10-25 volume per cent oleum being preferred. For maximum yields of oilsoluble sulphonate, 3 to 7 mols. of SO3 per mol. of sulphonatable hydrocarbon are used when sulphuric acids or oleum are employed, and 1.5 mols. to 3.5 mols. of SO3 per mol. of sulphonatable hydrocarbon when gaseous or liquid SO3 is used. The reaction temperature is not greater than 0 DEG , preferably not greater than -10 DEG C. The sulphonating agent, either alone or dissolved in liquid SO2, is added to the hydrocarbon and not the reverse order of addition. The reaction vessel may be a highspeed type of turbo or sheer mixer comprising internal or external heat exchanger means. Neutralization of the reaction mixture may be effected with a basic alkali metal or alkaline earth metal compound, usually aqueous or solid caustic soda or soda ash, and the hydrophilic solvent is preferably a C1 to C4 alcohol. The temperature should be maintained at 0 DEG to + 10 DEG C. until the mass is neutralized and then the temperature can be allowed to rise to room temperature. The quantity of alcohol used may vary from 50 to 150% based on the volume of feedstock. The solvent used for the countercurrent extraction of the neutralized mass is preferably a hydrophobic solvent such as benzene, xylenes and halogenated hydrocarbons. The oil-soluble sulphonates make excellent engine detergents and rust preventives. Specification 670,620 is referred to.