Abstract: In light colored surfactants produced by sulfonation of fatty acid alkyl esters with less than 2 moles of SO.sub.3 per mole of fatty acid alkyl ester and subsequent work-up of the crude sulfonate in aqueous medium to form salts, the content of .alpha.-sulfofatty acid disalts is regulated and reduced by transesterifying the sulfonation product before its treatment with an aqueous medium with at least about 0.5 mole equivalent of an alcohol, based on the SO.sub.3 which is not for .alpha.-sulfonation.

Abstract: The sulfonation of epoxidized ricinoleic acid glycerides with a dry stream of gaseous sulfur trioxide diluted with a carrier gas, followed by a reaction of the sulfonated reaction product with nucleophiles, leads to salt-free and anhydrous products showing surface-active properties.

Abstract: In the production of washing-active .alpha.-sulfofatty acid esters by sulfonation of fatty acid alkyl esters with SO.sub.3 in molar ratios of up to 1:2 and more especially of from 1:1.2 to 1:1.8 and subsequent working-up of the crude sulfonic acid in aqueous medium with salt formation, aqueous pastes which are mobile, more especially pumpable, at moderately elevated temperatures are obtained by subjecting the crude sulfonate before the treatment with the aqueous medium to a post-reaction with at least about 0.5 mole equivalent, based on the SO.sub.3 which is not used for the .alpha.-sulfonation, of monohydric alcohols and/or alkoxylation products thereof at temperatures above 70.degree. C. and adjusting the solids contents of the .alpha.-sulfofatty acid ester salts to more than 35% by weight in the subsequent aqueous working-up step.

Abstract: In light colored surfactants produced by sulfonation of fatty acid alkyl esters with less than 2 moles of SO.sub.3 per mole of fatty acid alkyl ester and subsequent work-up of the crude sulfonate in aqueous medium to form salts, the content of .alpha.-sulfofatty acid disalts is regulated and reduced by transesterifying the sulfonation product before its treatment with an aqueous medium with at least about 0.5 mole equivalent of an alcohol, based on the SO.sub.3 which is not for .alpha.-sulfonation.

Abstract: Aqueous concentrates of alkali metal salts of .alpha.-sulfonated fatty acid alkyl esters (ester sulfonate salts) which are pumpable at temperatures of at least 60.degree. C. are obtained without the addition of viscosity regulators by preparing pastes containing at least about 60% by weight of ester sulfonate salts derived from C.sub.16 and/or C.sub.18 fatty acids. More particularly, the concentrates contain less than 10 mole % of ester sulfonate salts with fatty acids containing fewer than 16 carbon atoms. The concentrates are obtained by neutralizing the crude ester sulfonates with concentrated alkali hydroxide solution with intensive cooling at temperatures of at most 90.degree. C.