Method for producing fatty acid polyglycol ester sulphates

Details Method for producing fatty acid polyglycol ester sulphates Method for producing fatty acid polyglycol ester sulphates

2000-05-22

2001-05-22

Carr, Deborah D. (Department: 1621)

Organic compounds -- part of the class 532-570 series

Organic compounds

Fatty compounds having an acid moiety which contains the...

C554S097000, C516S200000

Reexamination Certificate

active

06235913

ABSTRACT:

CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a 35 U.S.C. §371 national stage application based upon International Application No. EP98/05209, filed on Aug. 17, 1998.
BACKGROUND OF THE INVENTION
For some time, fatty acid polyethylene glycol esters, more particularly fatty acids with a low degree of ethoxylation, such as fatty acid +1EO adducts, have been described in the literature as interesting intermediates for the synthesis of ether sulfate surfactants with an isethionate-like structure. At first, however, difficulties were involved in producing the fatty acid polyethylene glycol esters used as starting compounds in satisfactory selectivities. Apart from the unwanted percentage of relatively highly ethoxylated homologs, significant quantities of polyethylene glycol and diesters were also formed by the relatively old known processes. Only recently has it been possible to produce fatty acids with low degrees of ethoxylation in yields of more than 90% of the theoretical by using special alkanolamines as ethoxylation catalysts. Apart from the fact that it was already difficult enough to provide the starting compounds in suitable qualities, the sulfation of these compounds also presented considerable difficulties. Although, according to the artide by K. Engel and W. Rubak in Fette, Seifen, Anstrichm., 88, 20 (1986), sulfated fatty acid polyethylene glycol esters can be obtained by reacting fatty acid polyglycol esters with chlorosulfonic acid in methylene chloride, only traces of anionic surfactants could be detected after neutralization under standard conditions. In other words, the mixture left after neutralization contained hardly any more anionic sulfated fatty acid polyethylene glycol esters, but mainly hydrolysis products, such as fatty acids, soaps, short-chain glycol monosulfates and glycol disulfates. Better results were obtained when the neutralization step was carried out at temperatures of 0 to −20° C. However, a process such as this would be unsuitable for industrial-scale production because, on the one hand, methylene chloride is used as solvent and would have to be removed in a separate working-up step and, on the other hand, cooling for working temperatures below 0° C. would only be possible on an industrial scale at enormous cost.
Accordingly, the problem addressed by the present invention was to provide an improved process for the sulfation of fatty acids, especially fatty acids with a low degree of alkoxylation, which could be used on an industrial scale to provide fatty acid polyglycol ester sulfates without any further working up.
BRIEF SUMMARY OF THE INVENTION
The present invention includes a process for the production of fatty acid polyglycol ester sulfates by sulfation of fatty acid polyglycol esters and subsequent neutralization and to their use as foam boosters, especially for surfactant mixtures containing nonionic surfactants.
The present invention relates to a process for the production of fatty acid polyglycol ester sulfates corresponding to formula (I):
R
1
COO(AO)
n
SO
3
M  (I)
in which R
1
CO is a linear or branched, aliphatic, saturated and/or unsaturated acyl group containing 6 to 22 carbon atoms, AO stands for CH
2
CH
2
O, CHCH
3
CH
2
O and/or CH
2
CHCH
3
O, n is a number of 0.5 to 5 and M is a cation, by sulfation of fatty acid polyglycol esters and subsequent neutralization, characterized in that the entire neutralization step is carried out at a pH value of 5 to 9.
It has surprisingly been found that, by carrying out the neutralization step under the described conditions, fatty acid polyglycol ester sulfates are obtained in high yields and the problem of hydrolysis is reliably avoided.
DETAILED DESCRIPTION OF THE INVENTION
Fatty Acid Polyglycol Esters
The sulfation products are produced from fatty acid polyglycol esters corresponding to formula (II):
R
1
COO(AO)
n
H  (II)
in which R
1
CO is a linear or branched, aliphatic, saturated and/or unsaturated acyl group containing 6 to 22 carbon atoms, AO stands for CH
2
CH
2
O, CHCH
3
CH
2
O and/or CH
2
CHCH
3
and n is a number of 0.5 to 5. The esters may be prepared by known methods of preparative organic chemistry, for example by addition of ethylene oxide and/or propylene oxide onto fatty acids in the presence of a base as homogeneous catalyst.
Fatty acids in the context of the invention are understood to be aliphatic carboxylic acids corresponding to the formula R
1
COOH, in which R
1
CO is an aliphatic, linear or branched acyl group containing 6 to 22 and preferably 12 to 18 carbon atoms and 0 and/or 1, 2 or 3 double bonds. Typical examples are caproic acid, caprylic acid, 2-ethylhexanoic acid, capric acid, lauric acid, isotridecanoic acid, myristic acid, palmitic acid, palmitoleic acid, stearic acid, isostearic acid, oleic acid, elaidic acid, petroselic acid, linoleic acid, linolenic acid, elaeostearic acid, arachic acid, gadoleic acid, behenic acid and erucic acid and the technical mixtures thereof obtained, for example, in the pressure hydrolysis of natural fats and oils, in the reduction of aldehydes from Roelen's oxosynthesis or as monomer fraction in the dimerization of unsaturated fatty acids. Technical fatty acids containing 12 to 18 carbon atoms, for example coconut, palm, palm kernel or tallow fatty acid, are preferred. Accordingly, R
1
CO in formulae (I) and (II) is preferably an acyl group containing 12 to 18 carbon atoms.
Alkoxylation
Suitable basic catalysts for the alkoxylation step are both alkanol-amines, such as monoethanolamine, diethanolamine and preferably tri-ethanolamine, and the amines described in DE 2024050 AS, such as mono-, di- and trimethylamine, mono-, di- and triethylamine, mono-, di- and tri-n-butylamine, tertbutylamine, mono-, di- and tripropylamine, diisopropyl-amine, n-hexylamine, n-dodecylamine, N,N-dimethyl-n-dodecylamine, N,N-dimethyloctadecylamine, docosylamine, hexamethylenediamine, N,N,N′, N′-tetramethyl hexamethylenediamine, tetraethylene pentamine, triethylene-diamine, cyclohexylamine, aniline, benzylamine, hexamethylenetetramine, diethylenetriamine, N,N-dimethyl aniline, methoxyanilines and morpholine. The described alkanolamines are particularly preferred catalysts. The alkanolamines are used in quantities of normally 0.1 to 5% by weight and preferably 0.5 to 1.5% by weight, based on the fatty acids. The alkoxylation step may be carried out in known manner. The fatty acid and the catalyst are normally introduced into a stirred autoclave from which traces of water are removed before the reaction by alternate evacuation and purging with nitrogen. The fatty acid is then reacted with ethylene oxide and/or propylene oxide in a molar ratio of 1:0.5 to 1:5 and preferably 1:1 to 1:2 which may be introduced into the pressure vessel in portions via a siphon after heating. Accordingly, the index n in formulae (I) and (II) is a number of 0.5 to 5 and preferably a number of 1 to 2. The alkoxylation may be carried out at temperatures of 80 to 180° C. and preferably 100 to 120° C. under autogenous pressures of 1 to 5 bar and preferably 2 to 3 bar. On completion of the reaction, it is advisable to stir the reaction mixture for a certain time (15 to 90 mins.) at the reaction temperature in order to complete the reaction. The autoclave is then cooled and vented and, if desired, acids, for example lactic acid or phosphoric acid, are added to the product in order to neutralize the basic catalyst. According to the invention, both ethoxylated or propoxylated or even ethoxylated and propoxylated fatty acids may be used as starting compounds. If ethoxylated and pro-poxylated fatty acids are used, they may be random or even block compounds. In the case of the mixed-alkoxylated fatty acids, the ratio of ethylene oxide to propylene oxide to be used may be varied within wide limits as long as, overall, the degree of alkoxylation n is in the range mentioned above. However, the consistency of the alkoxylated fatty acid can be influenced through the percentage content of propylene oxide. Thus, the softening tempera

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