Method for producing carbohydrate partial esters

Abstract

A process for the production of carbohydrate partial esters by transesterification of glycoses with fatty acid esters in the presence of emulsifiers and a catalyst mixture, to produce products with utility in the production of foods, cosmetic preparations, and in superabsorbancy applications.

Claims

1. A solventless process for the production of carbohydrate partial esters, comprising the steps of: (a) mixing, in the absence of solvent, C.sub.16/C.sub.18 fatty acid methyl esters and potassium carbonate to form a catalytically-active system; and (b) adding, with continuous stirring, one or more glycoses containing 5 to 12 carbon atoms, and one or more emulsifiers comprising carbohydrate partial esters, to said catalytically-active system from step (a), wherein an esterification reaction dispersion is formed; wherein the improvement comprises increasing the esterification reaction rate by the steps of: (c) adding sodium hypophosphite prior to mixing in step (a) or prior to stirring in step (b); (d) removing water from the resulting mixture with continuous stirring at a temperature of up to 100° C., and under a pressure of up to 50 mbar; and (e) continuing the esterification reaction under a pressure of up to 50 mbar and at a temperature of up to 125° C., with continuous stirring, until the content of the C.sub.16/C.sub.18 fatty acid methyl esters has fallen to at least 8%, by weight, based on the composition as a whole; wherein the potassium carbonate is mixed in an amount of 0.06 mol to 0.16 mol per mol of glycoses; wherein the sodium hypophosphite is added in an amount of 0.01 mol to 0.1 mol per mol of glycoses; and wherein the so-produced carbohydrate partial esters have an average degree of esterification of 1 to 4.

2. A solventless process for increasing a reaction rate of an esterification reaction for production of carbohydrate partial esters in the presence of a reduced amount of a catalyst mixture of one or more alkali metal carbonates, the process comprising the steps of: (a) mixing, in the absence of solvent, C.sub.16/C.sub.18 fatty acid methyl esters and potassium carbonate to form a catalytically-active system; (b) adding, with continuous stirring, one or more glycoses containing 5 to 12 carbon atoms, and one or more emulsifiers comprising carbohydrate partial esters, to said catalytically-active system from step (a), wherein a dispersion is formed, and removing water from the resulting mixture with continuous stirring at a temperature of up to 100° C., and under a pressure of up to 50 mbar; adding sodium hypophosphite prior to mixing in step (a) or prior to stirring in step (b); and (c) continuing the esterification reaction under a pressure of up to 50 mbar and at a temperature of up to 125° C., with continuous stirring, until the content of the C.sub.16/C.sub.18 fatty acid methyl esters has fallen to at least 8% by weight, based on the composition as a whole; wherein the potassium carbonate is mixed in an amount of 0.06 mol to 0.16 mol per mol of glycoses; wherein the sodium hypophosphite is added in an amount of 0.01 mol to 0.1 mol per mol of glycoses; and wherein the so-produced carbohydrate partial esters have an average degree of esterification of 1 to 4.

3. The process of claim 2, wherein: the potassium carbonate is mixed in an amount of 0.1 mol to 0.15 mol per mol of glycoses; the glycose comprises sucrose; and the carbohydrate partial ester comprises a sucrose partial ester esterified with C.sub.16 and/or C.sub.18 fatty acids.

4. The process according to claim 2, wherein the average degree of esterification is 3 to 4.

5. The process according to claim 2, wherein step (a), step (b) and step (c) are carried out in an inert gas atmosphere.

6. The process of claim 2, wherein the potassium carbonate and the C.sub.16/C.sub.18 fatty acid methyl esters are mixed at 50 to 100° C.

7. The process of claim 2, wherein the carbohydrate partial ester is a sucrose partial ester.

8. The process of claim 7, wherein the sucrose partial ester is sucrose esterified with C.sub.16 and/or C.sub.18 fatty acids.

9. The process of claim 7, wherein the glycose is sucrose.

10. The process of claim 2, wherein water is removed in step (b) at 70-85° C. under a pressure of 1-25 mbar.

11. The process according to claim 2, wherein said carbohydrate partial esters are used for the production of food, cosmetic or superabsorbing end products and said emulsifiers comprise partial esters of carbohydrates, wherein the carbohydrate unit is identical to that of the end product in which the carbohydrate partial esters are to be used.

12. The process according to claim 2, wherein the product from step (c) is further dissolved in an emollient suitable for cosmetic applications or for food applications and, after removal of the unreacted glycoses, is bleached with hydrogen peroxide, under nitrogen, to produce a bleached product.

13. The process according to claim 12, wherein said emollient comprises a hydrocarbon.

14. The process according to claim 13, wherein said hydrocarbon comprises a polyisobutene, liquid at 20° C.

15. The process according to claim 12, wherein a C.sub.16-C.sub.40 fatty alcohol or a mixture of C.sub.16-C.sub.40 fatty alcohols is added to the product from step (c) to produce a product, which is pelleted, extruded, granulated, crystallized, spray-dried or tabletted.

16. The process according to claim 15, wherein said fatty alcohol comprises a C.sub.18-C.sub.30 fatty alcohol or a mixture of such fatty alcohols.

17. The process according to claim 16, wherein said fatty alcohol comprises a C.sub.20-C.sub.24 fatty alcohol or a mixture of such fatty alcohols.

18. The process according to claim 15, wherein following addition of one or more fatty alcohols, the product is bleached with hydrogen peroxide.

Description

EXAMPLES

Example 1 (Laboratory Scale)

(1) The synthesis was carried out in a gentle stream of nitrogen introduced into the reaction mixture.

(2) 636.7 g (2.2 mol) of hydrogenated palm fatty acid methyl ester (Edenor® ME AS 16 V) were introduced into a 2 kg double-jacketed glass reactor, heated to 65° C., and equipped with a high-speed stirrer, reflux condenser and dropping funnel. 26.7 g (0.19 mol) of potassium carbonate, corresponding to 4%, by weight, based on the methyl ester, were then added at a stirrer speed of 1300 r.p.m., and the mixture was stirred for 10 minutes. 134 g (0.16 mol) of sucrose distearate (Sisterna® SP 30C) were added, in portions, to the dispersion thus obtained, and, after stirring for 10 minutes at 1500 r.p.m., 503 g (1.47 mol) of sucrose (powdered sugar from Beguin Say) were added, followed by stirring for 20 minutes at 2000 r.p.m 2 g (0.023 mol) of sodium hypophosphite were then added, the stirrer speed being kept at 2000 r.p.m. The resulting emulsion/dispersion was heated to 85° C., under a pressure of 1 to 5 mbar, followed by stirring for another 30 minutes. The temperature was then slowly increased to 125° C. and the reaction mixture was stirred for another 11 h at a stirrer speed of 2000 r.p.m. A sucrose ester containing 14%, by weight, monoester, 22%, by weight, diester, 30%, by weight triester, and 34%, by weight, tetraester and higher homologs, based on the total quantity of carbohydrate ester, was obtained. The content of unreacted ester in the reaction mixture was ca. 5%, by weight, and the content of free sucrose 4%, by weight.

(3) Working Up:

(4) After the reaction mixture had been cooled to ca. 110° C., 244 g of Panalane L 14 E (Amoco) were added and the mixture was homogenized by stirring for ca. 15 minutes. The hot solution was filtered off through a filter, using Seitz Ultra® as a filtration aid, and was bleached for 1 hour under nitrogen with 15 ml (0.29 mol) of a 35% (% by weight) hydrogen peroxide solution. The pH was adjusted by addition of 7.2 ml of an 80% lactic acid solution (% by weight), and the solution was subjected to another filtration with Seitz Ultra®. 2% by weight (based on the composition as a whole) of behenyl alcohol was added at 80° C. and, after homogenization by stirring, the product was pelleted.

Example 2 (Industrial Scale)

(5) The reaction was carried out as in Example 1, after scaling up to an industrial scale. 887 kg palm fatty acid methyl ester, 37 kg catalyst mixture (potassium carbonate and sodium hypophosphite), 187 kg sucrose distearate and 700 kg sucrose were reacted with one another. A sucrose ester containing 12.3%, by weight, monoester, 25.1%, by weight, diester, 33.1%, by weight, triester, 31.5%, by weight, tetraester and higher homologs, based on the total quantity of carbohydrate ester, was obtained. The content of unreacted ester in the reaction mixture was ca. 6%, by weight. Working up was carried out as in Example 1.

(6) Working Up

(7) The product obtained in Example 2 was worked up with a hydrogenated palm fatty acid methyl ester (Edenor® ME AS 16V) instead of Panalane L 14 E.

(8) After the reaction mixture had been cooled to ca. 100° C., 320 kg of palm fatty acid methyl ester (Edenor® ME AS 16 V; Cognis) were added and the mixture was homogenized by stirring for ca. 45 minutes. The hot solution was filtered off through a filter, using Seitz Ultra® as a filtration aid, and was bleached for 45 minutes, under nitrogen, at 85° C. with 10 kg of a 35% (% by weight) hydrogen peroxide solution. The pH was adjusted by addition of 9 kg of an 80% lactic acid solution (% by weight) and the solution was subjected to another filtration with Seitz Ultra®.

(9) TABLE-US-00001 TABLE 1 Assessing the influence of the quantity of catalyst, potassium carbonate (comparison), on the conversion of the fatty acid methyl ester The reaction was carried out as in Example 1. A C.sub.16/C.sub.18 fatty acid methyl ester with a ratio of C.sub.16:C.sub.18 fatty acid of 50:50 was used as the fatty acid methyl ester (ME). Sisterna ® SP 30 C was used as the carbohydrate partial ester (SE). The % by weight catalyst (K.sub.2CO.sub.3) relates to the content in the composition as a whole. The expression of the conversion in % relates to %, by weight, of the fatty acid methyl ester in the reaction mixture as a whole. K.sub.2CO.sub.3 K.sub.2CO.sub.3 K.sub.2CO.sub.3 5% bw C1 2.5% bw C2 1.5% bw C3 Conversion % ME Conversion % ME Conversion % ME  3 h 31.2 30.9 41.1  4 h 27.5 27.3  5 h 22.0 28.9 31.4  6 h 19.1  7 h 15.7 24.8 23.8  8 h 10.7  9 h 10.2 19.5 10 h  7.1 11 h 13.0 ME 475 g 287.5 g 640.2 g SE 100 g 102.6 g 123.8 g K.sub.2CO.sub.3  50 g   25 g  19.5 g Sucrose 375 g 384.9 g 505.4 g

(10) TABLE-US-00002 TABLE 2 Comparison between the catalyst mixture (B1) according to the invention and alkali metal carbonates (C4 and C5) The reaction was carried out as in Example 1. A C.sub.16/C.sub.18 fatty acid methyl ester with a ratio of C.sub.16:C.sub.18 fatty acid of 50:50 was used as the fatty acid methyl ester (ME). Sisterna ® SP 30 C was used as the carbohydrate partial ester (SE). The % by weight catalyst (K.sub.2CO.sub.3 as C4; K.sub.2CO.sub.3 and NaH.sub.2PO.sub.2 as B1 and Na.sub.2CO.sub.3 as C5) relates to the content in the composition as a whole. The expression of the conversion in % relates to % by weight of the fatty acid methyl ester in the reaction mixture as a whole. K.sub.2CO.sub.3 2.5% bw K.sub.2CO.sub.3 1.9% bw 2.5% bw C4 0.2% bw NaH.sub.2PO.sub.2 B1 Na.sub.2CO.sub.3 C5 Conversion % ME Conversion % ME Conversion % ME  3 h 30.9 28.4 42.2  4 h 27.3  5 h 28.9 19.7 38.1  6 h  7 h 24.8 13.3 No further change  8 h No further change  9 h 10.2 No further change 10 h 7.1 3.9 No further change ME 487.5 g 634.3 g 637.5 g SE 102.6 g 133.4 g 134.2 g K.sub.2CO.sub.3  2.5 g  32.5 g — Sucrose 384.5 g 500.4 g 503.4 g Na.sub.2CO.sub.3 — —    25 g

(11) TABLE-US-00003 TABLE 3 Catalyst compositions according to the invention and percentage conversion of the C.sub.16/18 fatty acid methyl ester The reaction was carried out as in Example 1. A C.sub.16/C.sub.18 fatty acid methyl ester with a ratio of C.sub.16:C.sub.18 fatty acid of 50:50 was used as the fatty acid methyl ester (ME). Sisterna ® SP 30 C was used as the carbohydrate partial ester (SE). The %, by weight, of the catalyst mixture according to the invention relates to the content in the composition as a whole. The expression of the conversion in % relates to %, by weight, of the fatty acid methyl ester in the reaction mixture as a whole. 2.5% bw K.sub.2CO.sub.3 1.9 % bw K.sub.2CO.sub.3 1.5% bw K.sub.2CO.sub.3 0.2% bw NaH.sub.2PO.sub.2 0.1% bw NaH.sub.2PO.sub.2 0.5% bw NaH.sub.2PO.sub.2 B2 B3 B4 Conversion % ME Conversion % ME Conversion % ME  3 h 28.4 24.5  4 h  5 h 19.7 21.5  6 h  7 h 13.3 9.2 15.6  8 h  9 h 4.8 10 h 3.9 6.3 11 h 3.6 ME 634.3 g 636.7 g   637 g SE 133.4 g   134 g 134.2 g K.sub.2CO.sub.3  32.5 g  24.7 g  19.2 g NaH.sub.2PO.sub.2  2.6 g    2 g  6.5 g Sucrose 500.4 g 502.6 g 502.8 g