GB1084770A - Process for isolating mahogany sulfonic acids - Google Patents

Abstract

A process for preparing oil-soluble mahogany sulphonic acid comprises (a) physically treating a sour oil, obtained by sulphuric acid treatment of a hydrocarbon oil, to remove pepper sludge and acid gases therefrom, said sour oil contain ing oil-soluble mahogany sulphonic acid; (b) intermingling said treated oil with water in an amount of 1-6% by weight, based on the treated oil, at 60-125 DEG F. for 3-180 minutes; (c) intermingling methanol with the oil from step (b) in an amount of 3-16 weight per cent based on the said treated oil, at 60-125 DEG F. for 1-180 minutes; (d) separating the oil from step (c) into a raffinate phase consisting of essentially decreased mahogany sulphonic acid content, and an extract phase comprising water, methanol, oil-soluble mahogany sul phonic acid and other acidic bodies; (e) inter mingling said extract phase with a calcium base at 50-100 DEG F. for 5-60 minutes, using 1-2 "theories" of base, where one "theory" corresponds to the theoretical amount of base needed to neutralize the inorganic acidity of the said extract phase and (f) separating solid bodies from the product of step (e) to obtain a liquid phase consisting essentially of oil-soluble mahogany sulphonic acid, water and methanol, being essentially free of inorganic salts. In step (a) "sulphuric acid" includes all types and forms of the acid as known in the art for sulphonation, and in step (f) inorganic salts includes methyl hydrogen sulphate. The base used is preferably Ca(OH)2, CaO or CaCO3. "Essentially free of inorganic salt" means substantially less than 1%, usually less than 0.7% of such salts, based by weight on the mahogany sulphonic acid.