Organic compounds -- part of the class 532-570 series – Organic compounds – Fatty compounds having an acid moiety which contains the...
Patent
1992-12-14
1995-02-21
Dees, Jose G.
Organic compounds -- part of the class 532-570 series
Organic compounds
Fatty compounds having an acid moiety which contains the...
554 85, 554 96, 554 97, C07C30332
Patent
active
053917839
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This invention relates to a process for the production of light-colored pastes of .alpha.-sulfofatty acid alkyl ester alkali metal salts, in which hydrogen peroxide is used as sole bleaching agent to bleach the sulfonation product during neutralization of the .alpha.-sulfofatty acid alkyl ester.
STATEMENT OF RELATED ART
.alpha.-Sulfofatty acid alkyl ester alkali metal salts are acquiring increasing significance as surfactants for detergents and cleaning preparations based on renewable natural raw materials. In known processes, the .alpha.-sulfofatty acid alkyl ester alkali metal salts are obtained in the form of aqueous solutions or pastes by neutralization of .alpha.-sulfofatty acid alkyl esters which may be synthesized by reaction of lower fatty acid alkyl esters with gaseous SO.sub.3. In the final analysis, the basis for the production of the .alpha.-sulfofatty acid alkyl ester alkali metal salts are fats and oils of natural origin from which the lower fatty acid alkyl esters are obtained by lipolysis and subsequent esterification of the free fatty acids with lower alkanols or by transesterification of the natural triglycerides with lower alkanols. In both reactions, methanol is preferably used as the lower alkanol. The lower fatty acid alkyl esters are mixtures in which C.sub.6-22 fatty acid residues occur, the chain length distribution being dependent on the origin of the natural fats or oils. In many cases, these fatty acid mixtures are not used for the synthesis as such, but rather in the form of certain fractions. Sulfonation of the fatty acid ester mixtures with gaseous SO.sub.3 gives acidic .alpha.-sulfofatty acid alkyl esters which are converted into aqueous pastes of .alpha.-sulfofatty acid alkyl ester alkali metal salts by neutralization to a pH value of 6 to 8.
The crude .alpha.-sulfofatty acid alkyl esters and their alkali metal salts are more or less colored products which generally have to be treated with typical bleaches before and/or after neutralization. Various bleaching processes have become known in connection with the production of light-colored .alpha.-sulfofatty acid alkyl ester alkali metal salt solutions and pastes. Combined bleaching processes have been developed for effective product lightening. According to DE-AS 12 34 709, the acidic .alpha.-sulfofatty acid alkyl ester is initially treated with aqueous hydrogen peroxide solution in a first bleaching step. The partly bleached sulfonation product is then neutralized before it is exposed to the effect of more hydrogen peroxide solution or aqueous hypochlorite solution in a second bleaching step. According to DE-OS 33 19 591, the neutralized sulfonation product is first bleached with aqueous hypochlorite solution at pH values of 7 to 10. Hydrogen peroxide solution is then added at pH values of .ltoreq.7 to stabilize the color values reached. These processes are attended by the disadvantage that the desired high washing active substance contents of the .alpha.-sulfofatty acid alkyl ester alkali metal salt pastes, which are reached during neutralization, are reduced again by introduction of the aqueous bleach solutions. In the context of the present invention, washing-active substance (WAS) is understood to be the sum of .alpha.-sulfofatty acid alkyl ester alkali metal salt and the .alpha.-sulfofatty acid ester always present as secondary product.
One particular difficulty involved in the production and handling of aqueous .alpha.-sulfofatty acid alkyl ester alkali metal salt pastes arises out of their viscosity behavior in dependence upon the concentration of washing-active substance. In aqueous compositions, the .alpha.-sulfofatty acid alkyl ester alkali metal salts produced by conventional industrial processes (hereinafter also referred to in short as ester sulfonates) only form solutions or suspensions of such low viscosity that they flow sufficiently freely to guarantee uninterrupted completion of industrial processes at WAS contents of up to about 40% by weight and then again beyond solids con
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Colignon Dietmar
Dorra Erich
Lepper Herbert
Panthel Guenter
Pierron Francois
Carr Deborah D.
Dees Jos,e G.
Drach John E.
Henkel Kommanditgesellschaft auf Aktien
Jaeschke Wayne C.
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