Method for extracting phytosterols from tall oil pitch

Abstract

A method for extracting phytosterols from tall oil pitch. The method involves saponifying tall oil pitch using an alkali in a polyatomic alcohol, extracting unsaponified matter from the alkali-alcohol solution using a hydrocarbon solvent, subsequently removing the solvent by distillation, and concentrating the phytosterols, wherein a mixture of paraffin hydrocarbons is used as said hydrocarbon solvent, and, following extraction from the extraction solution, betulin is isolated by crystallization and the phytosterols are then concentrated by means of rectification. This method enables an increase in the extraction rate of phytosterols from a saponified tall oil pitch up to 95%, producing the end product with phytosterol content of at least 65% with unwanted betulin impurities at no more than 0.3%.

Claims

1. A method for extracting phytosterols from tall oil pitch, the method consisting of saponifying tall oil pitch with an alkali in a polyatomic alcohol, extracting unsaponified matter from the alkali-alcohol solution using a hydrocarbon solvent, subsequently removing the solvent by distillation, and concentrating the phytosterols, wherein a mixture of paraffin hydrocarbons with 8 to 17 carbon atoms is used as the hydrocarbon solvent, and, following the extraction, botulin is isolated from the extract solution by crystallization at a temperature of 50 to 83 C. and the phytosterols are then concentrated by means of rectification.

2. The method according to claim 1, wherein the tall oil pitch comprises up to 3% betulin by weight.

3. The method according to claim 1, wherein the crystallization of betulin is carried out at a temperature of 70 to 80 C.

4. The method according to claim 1, wherein the extraction of unsaponifiable matters is carried out at a temperature of 100 to 135 C.

5. The method according to claim 1, wherein a mixture of paraffin hydrocarbons with 10 to 13 carbon atoms is used as the hydrocarbon solvent.

Description

DETAILED DESCRIPTION OF THE EMBODIMENTS

(1) The claimed method is carried out in the following way.

(2) Tall oil pitch is saponified at the temperature of 80 to 135 C. with an alkali dissolved in polyatomic alcohol.

(3) The saponified tall oil pitch solution is extracted with a hydrocarbon solvent at the temperature of 100 to 135 C. Once the extraction and the separation of phases are completed, the raffinate solution comprising predominantly salts of resin and fatty acids dissolved in the polyatomic alcohol is removed from the bottom, while the extract solution of paraffin hydrocarbons comprising phytosterol neutral matters and impurities is collected from the top.

(4) The temperature of the extract solution collected from the top is decreased and the betulin impurity is crystallized out. Then the solvent is removed by distillation under a reduced pressure and the distillation residue is fed to a rectifying column to concentrate the phytosterols.

INDUSTRIAL APPLICABILITY

(5) Particular examples of the application of the claimed method are provided below.

Example 1

(6) A reactor is fed with 40-50% aqueous alkali solution and ethylene glycol. The mixture is mixed and added with tall oil pitch preliminarily heated up to the temperature of about 90 C., with the ratio of ethylene glycol to tall oil pitch being respectively 1:1. The reaction mass is heated up to the temperature of 125 to 130 C. and mixed at this temperature for 3 to 5 hours.

(7) The saponified tall oil pitch is extracted with a mixture of paraffin hydrocarbons C.sub.8-C.sub.10 in the same reactor at the temperature of 100 C. with the ratio of the saponified tall oil pitch to paraffin hydrocarbons of 1:2. Once being mixed, the mixture is left until the layers are completely separated, then the bottom layer is removed.

(8) The temperature of the top layerthe extract solutionis reduced down to 70 C. and the betulin impurity is crystallized for 3 to 6 hours with weakmixing. The formed betulin crystals are filtered. The filtrate comprising phytosterols is distilled to remove the solvent and the distillation residue is fed to a rectifying column to concentrate the phytosterols.

(9) The rectification is carried out on a glass column with the inner diameter of 20 mm having five theoretical plates under the residual pressure of 0.001 to 0.01 mbar. The temperature in the column still is 200 C., the temperature of the condenser is 70 C. The feed point of the column is in the middle.

(10) The extraction rate of phytosterols was 95.3%. The end product contained 65% of phytosterols, the betulin impurity was 0.2%.

Example 2

(11) The saponification of the tall oil pitch is carried out in a way similar to that of Example 1.

(12) The saponified tall oil pitch is extracted with a mixture of paraffin hydrocarbons C.sub.10-C.sub.13 in the same reactor at the temperature of 135 C. with the ratio of the saponified tall oil pitch to extractant of 1:2. Once being mixed, the mixture is left until the layers are completely separated, then the bottom layer is removed.

(13) The temperature of the top layerthe extract solutionis reduced to 65 C. and the betulin impurity is crystallized for 3 to 6 hours with weak mixing. The formed betulin crystals are filtered. The filtrate comprising phytosterols is fed to a rectifying column to concentrate the phytosterols.

(14) The extraction rate of phytosterols was 96.5%. The end product contained 68% of phytosterols, the betulin impurity was 0.2%.

Example 3

(15) The saponification is carried out in a way similar to that of Example 1.

(16) The process is distinguished in that the saponification is carried out in a propylene glycol medium with the weight ratio of the tall oil pitch to propylene glycol of 1:2 and with the use of a mixture of paraffin hydrocarbons C.sub.14-C.sub.17 as an extractant at the extraction temperature of 130 C.

(17) The rectification is carried out under the residual pressure of 0.001 mbar without reflux return. The other steps of the rectification process are identical to these of Example 1.

(18) The extraction rate of phytosterols was 98%. The end product contained 69.5% of phytosterols, the betulin impurity was 0.1%.

Example 4

(19) The saponification is carried out in a way similar to that of Example 1.

(20) The process is distinguished in that the saponification is carried out in a propylene glycol medium with the weight ratio of the tall oil pitch to propylene glycol of 1:2 and with the use of a mixture of paraffin hydrocarbons C.sub.14-C.sub.17 as an extractant at the extraction temperature of 105 C. The crystallization of betulin is carried out at 80 C.

(21) The reflux-to-product ratio during the rectification is 2. The other steps of the process are identical to those of Example 3.

(22) The extraction rate of phytosterols was 96%. The end product contained 66.3% of phytosterols, the betulin impurity was 0.2%.

Example 5

(23) The saponification is carried out in a way similar to that of Example 4.

(24) The crystallization of betulin is carried out at 50 C.

(25) The rectification is carried out on a glass column with the inner diameter of 20 mm having five theoretical plates under the residual pressure of 0.001 to 0.01 mbar. The temperature in the column still is 200 C., the temperature of the condenser is 70 C. The feed point of the column is in the middle.

(26) The extraction rate of phytosterols was 95.8%. The end product contained 65% of phytosterols, the betulin impurity was 0.1%.

(27) The results of the experiments carried out according to the proposed method and according to the prototype are provided in the Table.

(28) TABLE-US-00001 Extract Phytosterol T Extraction WF of extraction WF of End Product Sapon- sapon- conditions Extract phytosterol rate from betulin in WF of WF of ification ification, Extractant T extract, yield, % in extract, saponified extract, phytosterol, betulin Example condition C. type C. TOP % TOP, % % % % According TOP:PG = 160 Hexane 62 27.6 24.6 62.9 2.1 to the 1:1.5 prototype 1 TOP:EG = 125-130 C.sub.8-C.sub.10 100 28.8 25.2 95.3 65.0 0.2 1:1 mixture 2 TOP:EG = 125-130 C.sub.10-C.sub.13 135 40.5 21.1 96.5 68.0 0.2 1:1 mixture 3 TOP:PG = 125-130 C.sub.14-C.sub.17 130 35.8 35.1 98.0 2.4 69.5 0.1 1:2 mixture 4 TOP:PG = 125-130 C.sub.14-C.sub.17 105 29.0 28.0 96.0 66.3 0.2 1:2 mixture 5 TOP:PG = 125-130 C.sub.4-C.sub.17 105 28.5 27.8 95.8 65.0 0.1 1:2 mixture TOPtall oil pitch EGethyleme glycol PGpropylene glycol WFweight fraction

(29) Consequently the proposed method allows increasing the extraction rate of phytosterols from a saponified tall oil pitch up to at least 95%, producing the end product with phytosterol content of at least 65% with unwanted betulin impurities at no more than 0.3%.