METHOD FOR PREPARING GLYCERIDE TYPE POLYUNSATURATED FATTY ACIDS

Abstract

The present invention relates to a method for preparing glyceride type polyunsaturated fatty acids. The method comprises: firstly mixing a basic catalyst with glycerol or a glyceride uniformly; then adding the mixture to a polyunsaturated fatty acid material slowly, and carrying out an esterification reaction under certain conditions to obtain glyceride type polyunsaturated fatty acids, wherein the basic catalyst is a lower aliphatic alcohol sodium/potassium or a solution thereof. The procedure of the process is simple, has mild reaction conditions, short reaction time, high yield and good quality of the obtained product.

Claims

1. A method of preparing a glyceride type polyunsaturated fatty acid, comprising the following step: 1) feeding: firstly mixing a basic catalyst with glycerol or glyceride uniformly to form a mixture, then adding the mixture to a polyunsaturated fatty acid material slowly under stirring; wherein the basic catalyst comprises one or more of sodium alcoholate with formula R1-ONa, a solution of sodium alcoholate with formula R1-ONa, potassium alcoholate with formula R.sub.2—OK, and a solution of potassium alcoholate with formula R.sub.2—OK; wherein R1, R2 represent same or different C.sub.1˜C.sub.5 lower alkyl group; the polyunsaturated fatty acid material is a polyunsaturated fatty acid with a formula ##STR00005## wherein R.sub.6, R.sub.8, R.sub.10 are same or different C.sub.6˜C.sub.40 alkenyl group; R.sub.7, R.sub.9, R.sub.11 are same or different H or C.sub.1˜C.sub.4 alkyl group; 2) reaction: heating to 80˜200° C. of temperature after completion of feeding, and then recovering low boiling point substances produced by the reaction by condensating; and 3) washing and recycling product: cooling the reaction vessel to 0˜60□ after completion of the reaction, adding a small amount of water to extract the basic catalyst, and recovering a small amount of remaining water in an organic layer, to obtain a glyceride type polyunsaturated fatty acid product.

2. The method according to claim 1, wherein the glyceride type polyunsaturated fatty acid is selected from the group consisting of triglyceride polyunsaturated fatty acid, diglyceride polyunsaturated fatty acid, and monoglyceride polyunsaturated fatty acid.

3. The method according to claim 1, wherein the polyunsaturated fatty acid material is selected from the group consisting of free type polyunsaturated fatty acid, methyl ester type polyunsaturated fatty acid and ethyl ester type polyunsaturated fatty acid.

4. The method according to claim 3, wherein the polyunsaturated fatty acid material is selected from the group consisting of fish oil, algae oil, linoleic acids, conjugated linoleic acids, linolenic acids, and arachidonic acids.

5. The method according to claim 1, wherein the content of the polyunsaturated fatty acid of the polyunsaturated fatty acid material is 10˜100 wt %.

6. The method according to claim 1, wherein the glyceride comprises a glyceride with a formula ##STR00006## wherein R.sub.3, R.sub.4, R.sub.5 represent hydroxyl group or C.sub.1˜C.sub.4 lower carboxylic acid group, R.sub.3, R.sub.4, R.sub.5 are same or different, but R.sub.3, R.sub.4, R.sub.5 cannot be simultaneously a hydroxyl group.

7. The method according to claim 6, wherein, R.sub.3, R.sub.4, R.sub.5 are formic acid group, acetic acid group, propionic acid group, n-butyric acid group, or isobutyric acid group.

8. The method according to claim 1, wherein, the C.sub.1˜C.sub.5 lower alkyl group is methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, isopentyl, or tert-pentyl.

9. The method according to claim 1, wherein the weight ratio of feeding amount of the polyunsaturated fatty acid material, the glycerol or the glyceride, and the basic catalyst is 100:1˜100:0.1˜10.

10. The method according to claim 1, wherein the time of the transesterification reaction is 1˜10 hours.

Description

DETAILED DESCRIPTION AND PREFERRED EMBODIMENTS THEREOF

[0037] Hereafter, the present invention will be described specifically with reference to the examples. The examples are given only for illustration of the technical solution of the present invention and should not be construed to limit the present invention.

Example 1

[0038] 50 g of glycerol and 1.0 g of sodium methoxide are mixed together, then 500 g of ethyl ester type fish oil material (EPA 22.1%, DHA 14.3%, the total content of the ethyl ester type polyunsaturated fatty acid is 59.8%) is added into a reaction flask to form a mixture. The mixture of glycerol and sodium methoxide is slowly added to the reaction flask under stirring, and then heating, and an esterification is carried out at 80° C. for 1.0 hour.

[0039] The reaction flask is cooled to 50° C., and adding 20 ml of water, stirring uniformly, and then standing for 10 minutes for layering. The upper organic layer is undergone under atmospheric pressure or reduced pressure to recycle a small amount of water, to obtain 496 g of a glyceride type polyunsaturated fatty acid product. The lower wastewater is acidated by adding dilute sulfuric acid to recycle a small amount of organic matter to get wastewater, and the wastewater reaches a discharge standard for directly discharge.

[0040] It may be seen by testing the glyceride type fish oil product that the product has 21.9% of EPA, 14.2% of DHA, and the total content of glyceride type polyunsaturated fatty acid is 60.12%, wherein the triglyceride polyunsaturated fatty acid is 95.5% of the glyceride type polyunsaturated fatty acid, and the total content of the ethyl ester polyunsaturated fatty acid is 0.07%, with 97.9% of yield, and good quality of the product.

Comparative Example 2

[0041] 50 g of glycerol and 5.0 g of sodium hydroxide are mixed together to form a mixture, and then 500 g of ethyl ester type fish oil material (EPA 22.1%, DHA 14.3%, the total content of the ethyl ester type polyunsaturated fatty acid is 59.8%) is added into a reaction flask. The mixture of glycerol and sodium hydroxide is slowly added to the reaction flask under stirring, and then heating, and then an esterification is carried out at 160° C. for 1.0 hour.

[0042] The reaction flask is cooled to 50° C., and adding 20 ml of water, stirring uniformly, and then standing for 10 minutes for layering. The upper organic layer is undergone under atmospheric pressure or reduced pressure to recycle a small amount of water, to obtain 472 g of a glyceride type polyunsaturated fatty acid product. The lower wastewater is acidated by adding dilute sulfuric acid to recycle a small amount of organic matter to get wastewater, and the wastewater reaches a discharge standard for directly discharge.

[0043] It may be seen by the testing glyceride type fish oil product that the product has 13.4% of EPA, 8.1% of DHA, and the total content of glyceride type polyunsaturated fatty acid is 20.12%, wherein the triglyceride polyunsaturated fatty acid is 36.2% of the glyceride type polyunsaturated fatty acid, and the total content of the ethyl ester polyunsaturated fatty acid is 15.72%, with 34.9% of yield, and the reaction is incomplete, with low yield and poor quality of the products.

[0044] It can be seen from Example 1 of the present invention that the process of the present invention obtains the glyceride type polyunsaturated fatty acid product by adding sodium methoxide as catalyst at milder reaction condition such as a lower temperature. The process is overall simple and easy to operate, has very high reaction degree, higher yield and better quality of product.

[0045] The comparative example 2 selects 160° C. as a temperature condition to obtain a glyceride type fish oil product by conventional esterification process of sodium hydroxide. But the process cannot be carried out at a low temperature condition. The reaction degree is lower because the activity of sodium hydroxide is lower. The content of glyceride type fish oil product is significantly reduced because parts of raw materials and products are destroyed. So the yield is very low, and the product quality is poor.

[0046] The process of the present invention selects lower aliphatic alcohol sodium or potassium or its solution as reaction catalysts. It could minimize amount of strong alkaline catalyst and reduce reaction temperatures to make process conditions milder. And slowly adding glycerol and diluent basic catalyst reduces destruction of strong basic catalysts on raw materials and the polyunsaturated fatty acid material. Besides selecting better process conditions improves reaction degree and shortens the reaction time, and finally obtains high quality of the glyceride type polyunsaturated fatty acid product.

[0047] The process of the present invention has such advantages as less catalyst, simple catalyst, low cost, simple equipment and simple process. The process is carried out by one step by one step, that is, a polyunsaturated fatty acid material is converted into a glyceride type polyunsaturated fatty acid with better quality product. The process of the present invention has good safety and environmental protection and is suitable for large-scale industrial production.

Examples 3-15

[0048] The objects of related parameters of Examples 3˜10 are listed in the following Table.

TABLE-US-00001 Relative Total Glycerol Content of content Polyunsaturated content of or Temper- glyceride type of triglyceride Exam- fatty acid polyunsaturated Glyceride Catalyst ature Reaction polyunsaturated polyunsaturated Yield ple material fatty acid (%) (g/g) (g/g) (° C.) time (Hr) fatty acid (%) fatty acid (%) (%) 3 Free type fish oil 13.5 Glycerol 0.10 Sodium methoxide 100 1 13.3 94.6 98.5 solution 0.010 4 Methyl ester 27.1 Glyceryl Sodium ethoxide 80 3 26.8 95.7 97.5 type fish oil triacetate 0.15 0.025 5 Free type algae 53.6 Triformin 0.20 Sodium ethoxide 140 2 53.1 94.9 97.9 oil solution 0.050 6 Ethyl ester type 68.5 Glycerol 0.05 Sodium methoxide 100 4 68.2 94.7 97.5 algae oil 0.001 7 Free type 42.1 Glycerol 0.10 Potassium ethoxide 100 6 41.9 95.3 98.1 linoleic acid 0.010 8 Methyl ester type 36.7 Tributyrin 1.00 Sodium isopropoxide 120 4 36.2 96.1 97.5 linoleic acid 0.050 9 Ethyl ester type 78.3 Glycerol 0.30 Potassium methoxide 180 7 78.1 95.8 98.5 linoleic acid solution 0.020 10 Free type 92.4 Glycerol 0.15 Sodium isobutoxide 130 8 92.0 94.8 97.9 conjugated solution 0.100 11 Ethyl ester type 46.7 Glyceryl Sodium tert-butoxide 100 3 46.2 96.0 98.1 conjugated triacetate 0.40 0.03 linoleic acid 12 Free type 46.9 Glyceryl Sodium tert-butoxide 80 6 46.3 95.2 97.5 linolenic acid triacetate 0.15 solution 0.10 13 Ethyl ester type 68.2 Tripropionin Sodium tert-amylate 140 10 68.0 95.1 98.5 linolenic acid 0.60 solution 0.10 14 Free type 53.2 Glycerol 0.65 Potassium 100 3 52.8 96.1 97.9 arachidonic acid tert-butoxide 0.02 15 Ethyl ester type 98.1 Glycerol Potassium 200 6 97.9 94.9 97.9 arachidonic acid triacetate 0.50 tert-butoxide 0.10 Note: the “Glycerol or Glyceride (g/g)” is referred to as the weight ratio of Glycerol or Glyceride (g) to Polyunsaturated fatty acid material (g); “Catalyst (g/g)” is referred to as the weight ratio of Catalyst (g) to Polyunsaturated fatty acid material (g); “Relative content of triglyceride polyunsaturated fatty acid (%)” is referred to as the ratio (%) of triglyceride polyunsaturated fatty acid to Total content of polyunsaturated fatty acid.

[0049] It can be seen from Examples 3˜15 of the present invention that the process has such advantages as less catalyst, simple and easily obtained catalyst, low cost, simple equipment and simple process. The process is basically carried out by one step reaction by direct conversion of the polyunsaturated fatty acid material to glyceride type polyunsaturated fatty acid. And the final product has better quality, high yield with more than 97.5%. The process of the present invention has good safety and environmental protection and is suitable for large-scale industrial production.

[0050] Although the present invention has been described in connection with the above embodiments, it should be understood that the present invention is not limited to such preferred embodiments and procedures set forth above. The embodiments and procedures were chosen and described in order to best explain the principles of the invention and its practical application, to thereby enable others skilled in the art to best utilize the invention. It will be apparent to those skilled in the art that various substitution, modifications and changes may be thereto without departing from the scope and spirit of the invention. Therefore, the intention is intended to cover all alternative constructions and equivalents falling within the spirit and scope of the invention as defined only by the appended claims and equivalents thereto.