Abstract:
Esterquats based on natural fats and oils can be directly produced by subjecting fatty acid glyerine ester to ester interchange, in the presence of alkaline and/or alkaline earth boron hydrides and hypophosphoric acid or their alkaline and/or alkaline earth salts and possibly free fatty acid, with hydroxy-functionalised tertiary amines and quaternising the resultant products in the manner known per se.

Description:
This application is a 371 of PCT/EP 95/00861 filed May 9, 1995. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a process for the production of esterquats, in which fatty acid glycerol esters are directly transesterified with tertiary hydroxyamines and then quaternized, and to the use of the products for the production of surface-active formulations. 
     2. Statement of Related Art 
     In recent years, quaternized fatty acid triethanolamine ester salts, socalled &#34;esterquats&#34;, have acquired increasing significance as ecotoxicologically safe raw materials for fabric softeners  cf. O. Ponsati in C.R. CED Congress, Barcelona, 167 (1992) and R. Puchta in C.R. CED Congress, Sitges, 59 (1993)!. 
     According to the teaching of International patent application WO 91/01295 (Henkel), esterquats are normally produced from triethanolamine or adducts of ethylene oxide with triethanolamine which, in a first step, are partly esterified with linear C 16/18  fatty acids in the presence of hypophosphorous acid and subsequently treated with air. The fatty acid triethanolamine esters are then quaternized, for example with alkyl halides or, preferably, dialkyl sulfates. 
     Instead of fatty acids themselves, it is desirable for economic reasons directly to use natural fats and oils, from which the fatty acids are obtained, as starting materials for the production of esterquats. However, according to studies conducted by applicants, application of this principle on an industrial scale has hitherto been prevented by the fact that transesterification in the presence of the alkaline catalysts typically used for this type of reaction, namely potassium hydroxide or sodium methylate, generally involves overly long reactor possession times and, in general, leads to discolored products which have to be bleached in an additional, expensive process step. 
     Accordingly, the problem addressed by the present invention was to provide a process for the production of esterquats based on fats and oils as starting materials which would not have any of the disadvantages mentioned above. 
     DESCRIPTION OF THE INVENTION 
     The present invention relates to a process for the production of esterquats in which fatty acid glycerol esters are subjected to transesterification with hydroxyfunctionalized tertiary amines in the presence of alkali metal and/or alkaline earth metal borohydrides and hypophosphorous acid or alkali metal and/or alkaline earth metal salts thereof and, optionally, free fatty acid and the resulting products are quaternized in known manner. 
     It has surprisingly been found that the use of borohydrides as opposed to other conventional transesterification catalysts leads to a quick and complete reaction which, in addition, gives reaction products that are distinguished by particularly high color quality. In addition, the process according to the invention affords the advantage that fats and oils can be directly used instead of fatty acids which increases the economy of the process. 
     Esterquats 
     Esterquats are generally understood to be quaternized fatty acid triethanolamine ester salts. These are known substances which may be obtained by the relevant methods of preparative organic chemistry, cf. International patent application WO 91/01295 (Henkel). According to this document, triethanolamine is partly esterified with fatty acids in the presence of hypophosphorous acid, air is passed through and the fatty acid triethanolamine esters are subsequently quaternized with dimethyl sulfate or ethylene oxide. U.S. Pat. No. 3,915,867, U.S. Pat. No. 4,370,272, EP-A2 0 239 910, EP-A2 0 293 955, EP-A2 0 295 739 and EP-A2 0 309 052 are cited at this juncture as representative of the extensive prior art on this subject. 
     The quaternized fatty acid triethanolamine ester salts correspond to formula (I): ##STR1## in which R 1  CO is an acyl radical containing 6 to 22 carbon atoms, R 2  and R 3  independently of one another represent hydrogen or have the same meaning as R 1  CO, R 4  is an alkyl radical containing 1 to 4 carbon atoms or a (CH 2  --CH 2  O) q  H group, m, n and p have a combined value of 0 or 1 to 12, q is a number of 1 to 12 and X is halide, alkyl sulfate or alkyl phosphate. 
     Typical examples of esterquats which may be used in accordance with the invention are products based on caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, isostearic acid, stearic acid, oleic acid, elaidic acid, arachic acid, behenic acid and erucic acid and the technical mixtures thereof obtained, for example, in the pressure hydrolysis of natural fats and oils. Technical C 12/18  cocofatty acids and, in particular, partially hydrogenated C 16/18  tallow or palm oil fatty acid and also C 16/18  fatty acid cuts rich in elaidic acid are preferably used. 
     Quaternized fatty acid triethanolamine ester salts corresponding to formula (I), in which R 1  CO is an acyl radical containing 16 to 18 carbon atoms, R 2  has the same meaning as R 1  CO, R 3  is hydrogen, R 4  is a methyl group, m, n and p have a combined value of 0 and X stands for methyl sulfate, have proved to be particularly advantageous from the performance point of view. 
     Besides the quaternized fatty acid triethanolamine ester salts, other suitable esterquats are quaternized ester salts of fatty acids with diethanol alkylamines corresponding to formula (II): ##STR2## in which R 1  CO is an acyl radical containing 6 to 22 carbon atoms, R 2  is hydrogen or has the same meaning as R 1  CO, R 4  and R 5  independently of one another represent alkyl radicals containing 1 to 4 carbon atoms, m and n have a combined value of 0 or 1 to 12 and X stands for halide, alkyl sulfate or alkyl phosphate. 
     Finally, another group of suitable esterquats are the quaternized ester salts of fatty acids with 1,2-dihydroxypropyl dialkylamines corresponding to formula (III): ##STR3## in which R 1  CO is an acyl radical containing 6 to 22 carbon atoms, R 2  is hydrogen or has the same meaning as R 1  CO, R 4 , Re and R 7  independently of one another represent alkyl radicals containing 1 to 4 carbon atoms, m and n have a combined value of 0 or 1 to 12 and X stands for halide, alkyl sulfate or alkyl phosphate. 
     So far as the choice of preferred fatty acids is concerned, the examples mentioned for (I) also apply to the esterquats of formulae (II) and (III). 
     Fatty acid glycerol esters 
     Fatty acid glycerol esters in the context of the invention are synthetic or preferably natural triglycerides, diglycerides, monoglycerides or technical mixtures thereof. The glycerol esters generally contain fatty acids with 6 to 22 and preferably 12 to 18 carbon atoms. They may be saturated or may contain up to 3 double bonds. In addition, the glycerol esters may contain one type of fatty acid or up to three different fatty acids. Typical examples of triglycerides which may be used in the process according to the invention are palm oil, palm kernel oil, coconut oil, olive oil, rapeseed oil from old and new plants, sunflower oil from old and new plants, cottonseed oil, linseed oil, peanut oil, beef tallow and lard. From the performance point of view, it is preferred to use completely or partly hydrogenated beef tallow or palm oil with iodine values in the range from 0 to about 50. 
     Hydroxyfunctionalized tertiary amines 
     In the transesterification reaction, at least one fatty acid of the glyceride reacts with one OH group of a hydroxyfunctionalized tertiary amine. Typical examples of suitable amines are diethanol alkylamines such as, for example, diethanol methylamine and 1,2-dihydroxypropyl dialkylamines such as, for example, 1,2-dihydroxypropyl dimethylamine and, in particular, triethanolamine. 
     The fatty acid glycerol esters--expressed on the basis of the fatty acids present in them--and the amines may be used in a molar ratio of around 1.2:1 to 2.2:1 and preferably 1.4:1 to 1.9:1. 
     Catalysts 
     Alkali metal and/or alkaline earth metal borohydrides may be used as the transesterification catalysts. Typical examples are potassium or magnesium borohydride and preferably sodium borohydride. The catalysts are normally used in quantities of 50 to 1000 
     ppm and preferably in quantities of 100 to 500 ppm, based on the glycerol ester. 
     Suitable co-catalysts are hypophosphorous acid and alkali metal and/or alkaline earth metal salts thereof, preferably sodium hypophosphite, used in quantities of 0.01 to 0.1% by weight and preferably in quantities of 0.05 to 0.07% by weight, based on the glycerol ester. 
     Fatty acids 
     In one preferred embodiment of the process according to the invention, the transesterification reaction takes place in the presence of free fatty acids containing 6 to 22 and preferably 12 to 18 carbon atoms which may be used in quantities of 1 to 5% by weight and, more particularly, 2 to 3% by weight, based on the glycerol ester. Typical examples of suitable fatty acids 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 or in the reduction of aldehydes from Roelen&#39;s oxosynthesis. 
     Technical fatty acids containing 12 to 18 carbon atoms, for example coconut oil, palm oil, palm kernel oil or tallow fatty acid, which correspond to the fatty acid of the triglyceride used are preferred. 
     Transesterification 
     The transesterification is normally carried out over a period of 1 to 12 hours and preferably 3 to 6 hours at temperatures in the range from 160° to 240° C. and preferably at temperatures in the range from 180° to 220° C. 
     Quaternization 
     The fatty acid hydroxyalkylamine esters and the quaternizing agents may be used in a molar ratio of 1:0.95 to 1:1.2 and preferably in a molar ratio of 1:1 to 1:1.1 in the quaternization reaction. Suitable alkylating agents are alkyl halides, for example methyl chloride, dialkyl sulfates, for example dimethyl sulfate, dialkyl phosphates and dialkyl carbonates, for example dimethyl carbonate or diethyl carbonate. The reaction usually takes place in a solvent, for example a lower alcohol (isopropyl alcohol), a fatty alcohol (ceteareth alcohol), a nonionic surfactant (alkyl oligoglucoside, adducts of ethylene oxide with fatty alcohols or partial glycerides) or a hydroxycarboxylic acid (glycolic acid). The quaternization is preferably carried out at temperatures of 70° to 100° C. and, more particularly, at temperatures of 80° to 90° C. The reaction time may be between 1 and 24 h and is preferably between 2 and 8 h. After the quaternization, it is advisable to destroy unreacted alkylating agent by addition of ammonia, glycine or monoethanolamine. 
     Commercial Applications 
     The esterquats obtainable by the process according to the invention are distinguished by excellent fabric-softening and antistatic properties. 
     Accordingly, the present invention also relates to their use for the production of fabric softeners and hair-care formulations, such as softeners for textiles, yarns and fibers, household fabric softeners, hair shampoos, hair conditioners, hair rinses and the like, in which they may be present in quantities of 1 to 30% by weight and preferably in quantities of 5 to 15% by weight, based on the particular formulation. 
    
    
     The following Examples are intended to illustrate the invention without limiting it in any way. 
     EXAMPLES 
     General production procedure 
     a) Esterification. 0.4 to 0.63 mole of triglyceride (corresponding to 1.2 to 1.9 mole, based on fatty acid), 149 g (1 mole) of triethanolamine, 0.05% by weight of sodium hypophosphite, 100 to 500 ppm of catalyst and, optionally, 2.7% by weight of tallow fatty acid (all percentages by weight based on the triglyceride) were introduced into a 1 liter three-necked flask equipped with a stirrer, internal thermometer and distillation head. The reaction mixture was heated for 5 h to a temperature of 220° C. The crude tallow fatty acid triethanolamine ester was then cooled, the reactor was vented and 1 liter of air was passed through over a period of 15 minutes with continuous stirring. 
     The results of the esterification tests are set out in Table 1. 
     b) Quatemization. In a 1.5 liter glass autoclave equipped with a stirrer and internal thermometer, 63 g (0.5 mole) of dimethyl sulfate were added to 0.5 mole of the ester according to a) in 150 ml of isopropyl alcohol. The reaction mixture was stirred for 2 h at 90° C. and, after cooling, the reactor was vented. To destroy traces of unreacted alkylating agent, 2 g of glycine were then added to the reaction mixture, followed by stirring for 1 h at 60° C. 
     
                       TABLE 1______________________________________Transesterification of Triglycerides                    c (Cat)                           c (FA)  t    ColorEx.  E     R       Cat   ppm    % by weight                                   h    Gardner______________________________________1    A     1.2:1   NaBH.sub.4                    100    2.7     4    1.02    A     1.6:1   NaBH.sub.4                    100    2.7     4    1.23    A     1.9:1   NaBH.sub.4                    100    2.7     4    1.54    A     1.9:1   NaBH.sub.4                    500    2.7     4    1.05    A     1.9:1   NaBH.sub.4                    100    --      4    1.56    B     1.9:1   NaBH.sub.4                    100    2.7     4    1.57    C     1.9:1   NaBH.sub.4                    100    2.7     4    1.5C1   A     1.9:1   KOH   100    2.7     6    3.5C2   A     1.9:1   NaOMe 100    2.7     7    3.5______________________________________ Legend: E = Educt A = Hydrogenated beef tallow B = Partly hydrogenated beef tallow C = Palm oil R = Ratio of fatty acid (in the triglyceride) to triethanolamine Cat = Catalyst FA = Fatty acid (corresponding to the triglyceride) c = Concentration t = Time required to establish an acid value &lt; 5