Organic compounds -- part of the class 532-570 series – Organic compounds – Fatty compounds having an acid moiety which contains the...
Reexamination Certificate
2000-08-18
2002-08-06
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...
Reexamination Certificate
active
06429324
ABSTRACT:
This application is a 371 of PCT/EP98/07907 filed Dec. 4, 1998.
BACKGROUND OF THE INVENTION
The addition of alkylene oxides to CH-acidic compounds such as, for example, fatty alcohols, alkylphenols, fatty amines or else fatty acids is one of the large-scale established methods for producing nonionic surfactants. These reactions are usually carried out in the presence of homogeneous basic catalysts, such as, for example, sodium hydroxide or sodium methoxide. However, the alkoxylation is not a very selective reaction, meaning that in practice, particularly at low alkoxylation ratios, the maximum resulting homolog distribution does not correspond to the average degree of alkoxylation.
Attempts have been made to counter this undesired effect by using catalysts which have higher selectivity and lead in total to alkoxylates, specifically ethoxylates, having a narrower (“narrowed”) homolog distribution; these products are frequently also referred in the literature as “narrow-range ethoxylates”. Suitable homogeneous catalysts for this purpose are, preferably, alkaline earth metal salts, such as, for example, barium phosphate or strontium ether carboxylates. Heterogeneous catalysts, such as, for example, calcined hydrotalcites, are also suitable for this purpose.
With regard to the ethoxylation of fatty acids, the efforts in the prior art nevertheless continue to be unsatisfactory. Particularly in the case of fatty acids with low degrees of ethoxylation, specifically fatty acid +1EO adducts, which are interesting as precursors for the synthesis of ether sulfate surfactants having isethionate-type structure, satisfactory selectivities have not been established. In addition to an undesired proportion of more highly ethoxylated homologs, significant amounts of polyethylene glycol and diesters, in particular, are also formed in the process. Even the method as in U.S. Pat. No. 3,884,946 (Henkel), which recommends the use of amines as catalysts for this purpose, produces fatty acids with a low degree of ethoxylation in yields significantly below 90% of theory. Better yields can be obtained for fatty acids with a low degree of ethoxylation if the method is carried out as in U.S. Pat. No. 5,936,107, issued Aug. 10, 1999 (Henkel).
In addition to an undesired proportion of more highly ethoxylated homologs, significant amounts of polyethylene glycol and diesters, in particular, are also formed in the process. Even the method as in U.S. Pat. No. 3,884,946 (Henkel), which recommends the use of amines as catalysts for this purpose, produces fatty acids with a low degree of ethoxylation in yields significantly below 90% of theory. Better yields can be obtained for fatty acids with a low degree of ethoxylation if the method is carried out as in American patent application Ser. No. 08/767,123.
According to this method, the ethoxylation is carried out in the presence of alkanolamines as catalysts and produces significantly higher yields.
According to European Laid-open Patent Specification EP-A-178 913, it is possible to alkoxylate not only straight-chain fatty acids, but also branched neocarboxylic acids having a tertiary carbon atom in an adjacent position to the carboxyl group in the presence of amines such as diethanolamine and triethanolamine with increased selectivity. However, in order to obtain good yields with this method, relatively high temperatures in the range of from 140 to 185° C. are necessary.
According to the cited prior art, the problem of selectivity during alkoxylation has only been investigated for monomeric carboxylic acids. However, to date, the problem of selective alkoxylation in the case of oligomeric carboxylic acids, in particular in the case of dimer fatty acids, has not been considered. There was therefore a need to provide a selective method also for the alkoxylation of dimer fatty acids.
BRIEF SUMMARY OF THE INVENTION
Consequently, the object of the present invention was to provide an improved homogeneously catalyzed method for producing alkylene glycol esters of dimer fatty acids, specifically dimer fatty acids with a low degree of alkoxylation, which has improved selectivity.
Surprisingly, we were able to achieve the object by alkanolamines, specifically triethanolamine, being present as catalyst during the alkoxylation of the dimer fatty acids. This process is particularly suitable for the preparation of dimer fatty acids which have a low degree of alkoxylation.
The present invention provides a method for producing alkylene glycol esters of dimer fatty acids by addition of alkylene oxide to dimer fatty acids in the presence of alkanolamines as catalysts.
For the purposes of the present invention, the terms “alkoxylated dimer fatty acids” and “alkylene glycol esters of dimer fatty acids” are used synonymously.
DETAILED DESCRIPTION OF THE INVENTION
Dimer Fatty Acids
For the purposes of the invention, the term dimer fatty acids means technical-grade mixtures obtained by oligomerization of unsaturated fatty acids or methyl esters thereof.
The oligomerization of unsaturated fatty acids is a known electrocyclic reaction reported in review articles, for example, by A. Behr in Fat Sci. Technol. 93, 340 (1991), G. Spiteller in Fat Sci. Technol. 94, 41 (1992) or P. Daute et al. in Fat Sci. Technol. 95, 91 (1993). During the oligomerization, on average two to three fatty acids come together and form dimers or trimers, which have predominantly cycloaliphatic structures. As well as the fraction of dimers and trimers, a so-called monomer fraction is obtained which contains unreacted starting materials and branched monomers formed in the course of the reaction by isomerization. In addition, there is of course also a fraction of higher oligomers, although this is usually not of any great significance. The oligomerization can be carried out thermally or in the presence of noble metal catalysts. The reaction is preferably carried out in the presence of clay earths, such as, for example, montmorillonite [cf. Fette, Seifen, Anstrichmitt. [Fats, Soaps, Coatings] 72, 667 (1970)]. The content of dimers and trimers or the extent of the monomer fraction can be controlled by the reaction conditions. Finally, technical-grade mixtures can be purified, including by distillation.
Suitable starting materials for the oligomerization are technical-grade unsaturated fatty acids having 12 to 22 carbon atoms, preferably 16 to 18 carbon atoms. Typical examples are palmoleic acid, oleic acid, elaidyl acid, petroselinyl acid, linoleic acid, linolenic acid, conjuene fatty acid, elaeostearic acid, ricinoleic acid, gadoleic acid, erucic acid, and technical-grade mixtures thereof with saturated fatty acids. Typical examples of suitable technical-grade mixtures are nonhydrogenated cleavage fatty acids of natural triglycerides having iodine numbers in the range from 40 to 140, such as, for example, palm fatty acid, tallow fatty acid, rape oil fatty acid, sunflower fatty acid and the like. Preference is given to cleavage fatty acids with a high content of oleic acid.
In addition to the fatty acids, it is also possible to dimerize the esters thereof, preferably methyl esters. It is likewise possible to oligomerize the acid and to convert it to the methyl ester prior to hydrogenation. Conversion of the ester group to the acid group is carried out in a manner known per se.
Dimer fatty acids which are particularly preferred for the purposes of the invention are obtained by oligomerization of technical-grade oleic acid and preferably have a dimer content of from 50 to 99% by weight, and a polymer content (including trimer content) of from 1 to 50% by weight. The content of monomers can be from 1 to 15% by weight and if necessary lowered by distillation. Particular preference is given to dimer fatty acids which are obtained by oligomerization of technical-grade oleic acid and have a dimer content of from 70 to 85% by weight, a polymer content of from 10 to 20% by weight and a monomer content of from 5 to 15% by weight. The % by weight are based here on the total amount of dimer fatty acid.
Alk
Behler Ansgar
Bongardt Frank
Raths Hans-Christian
Roeder Juergen
Carr Deborah D.
Cognis Deutschland and GmbH
Drach John E.
Ettelman Aaron R.
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