US3108120A - Process for recovery of tocopherols and sterols - Google Patents

Description

United States Patent Office ib hi h Patented Oct. 22, 1963 3,108,120 PROQESS FOR RECKJVERY OF TUCGPHEROLS AND STERULS Winton Brown and Kari H. Meng, Rochester, N.Y., as-

signors to Eastman Kodak Company, Rochester, N .Y., a corporation of New Jersey No Drawing. Filed Feb. 23, 1961, Ser. No. 90,933 7 Claims. (til. 260345.6)

This invention relates to the chemical arts. More particularly, it relates to an improvement in the lime soap process for recovering tocopherols and a sterols from vegetable oil and animal oil deodorizer distillates and the like.

The lime soap process for the treatment of materials containing tocopherols and sterols is well known in the art. One embodiment of this process is taught by Rossouw and Von Rudloff (J. Applied Chemistry, 2,335- 338, June 1952), who disclose lime saponification of wool wax followed by extraction of the unsaponifiable fraction with acetone in which the lime soaps are insolule. Another embodiment of this process is disclosed by Hickman in his US. Patent, No. 2,349,270, wherein siaked lime is added to a deodorizer distillate and the resulting lime soap mass broken up and extracted with ethyl ether. Still another embodiment is taught by Andrews in US. Patent No. 2,263,550. This patent discloses the saponification of a vegetable oil distillation residue containing vitamin E, followed by metathesis with calcium chloride to form calcium soaps which are then extracted with acetone to recover unsaponifiable matter. The unsaponifiable matter in each case comprises tocopherols and sterols.

When applying this process in any of its embodiments to vegetable oil deodorizer distillates and the like having a high concentration of unsaponifiable matter, a hard, wax-like gel between the soaps and unsaponifiable matter forms. This gel is difficult to leach with solvents for the tocopherols and sterols because of the relatively small surface of the gel or soap exposed to solvent action. Consequently, it is necessary to subdivide the soap into extractable form. This calls for heavy grinding or masticating machinery. Moreover, a large number of solvent extraction steps subsequently must be employed. Not only is solvent consumption or loss high but the yield of tocopherols and sterols is low. Hence, the lime soap process, when applied to vegetable oil deodorizer distillates and the like having a high concentration of unsaponifiable matter, is inherently uneconomical and requires a substantial capital investment. There is, therefore, a need for improvement of the lime soap process. A general object of this invention is to provide such an improvement.

More particularly, an object of this invention is to so improve the lime soap process that a subdivided soap in extractable form is obtained from deodorizer distillates and the like having a high concentration of unsaponifiable matter without the necessity of employing heavy grinding or masticating machinery.

Another object of this invention is to so improve the lime soap process that a subdivided soap is provided which requires a minimum number of solvent extraction steps to give high yields or recoveries of tocopherols and sterols with a minimum of solvent consumption.

These and other objects which may appear as this specification proceeds are achieved by this invention.

This invention, in summary, involves an improved lime soap process characterized by the presence of a powdering agent in the lime soap mass while extracting unsaponifiable matter therefrom with a selective solvent, a solvent in which tocopherols and sterols are soluble and the lime soaps are insoluble.

The powdering agent, which might also be called an extraction aid, is a finely divided, oil adsorbent, abrasive, inorganic solid insoluble in the solvent and inert relative to the components of the lime soap mass. Preferably the powdering agent is of colloidal particle size in order to provide adequate surface contact between the soap mixture and the extraction solvent. While inorganic solids of particle sizes larger than colloidal can be employed, they are not very efficient as powdering agents. A particularly efficacious powdering agent is colloidal calcium silicate. Other powdering agents that can be used are colloidal sodium silico-aluminate, finely divided alumina, colloidal silica and colloidal titania. Pulverized sodium sulfate and diatomite, for example, are not recommended because of the larger than colloidal particle size of the solids thereof. For this reason they are comparatively inefficient as powdering agents.

The powdering agent is introduced into the lime soap mass preferably while the soap mass is fluid or flowable and when the moisture content of the lime soap mass is, and will continue to be, preferably less than about five percent by weight of the lime soap mass, ideally at zero weight percent. It is necessary that the soap mass be fluid or at least plastic when the powdering agent is added because once the lime soap mass has set into a hard gel, addition of the powdering agent has no significant effect. The moisture content of the lime soap mass is another important factor in this invention. If too much moisture is present the powdering agent does not work properly. This is due probably to a preferential wetting of the powdering agent by water. Investigations have shown that the moisture concentration in the lime soap mass should preferably not exceed about five percent by weight of the mass. Hence, when these two conditions are present the powdering agent can be introduced into the lime soap mass during its formation (with the addition of the calcium ion bearing reagent to the saponified sludge) and it can be introduced into the lime soap mass at the solvent extraction step. Usually, however, it will be introduced into the lime soap mass after the mass has been subjected to a partial drying operation prior to the solvent extraction step. Introduction of the powdering agent to the lime soap mass is accomplished by admixture until the powdering agent is uniformly dispersed throughout the mass.

The concentration of the powdering agent in the lime soap mass should lie in a range from about 3 Weight percent to about 21 weight percent. At a concentration less than about 3 weight percent the powdering agent does not produce any significant effect while at a concentration greater than 21 weight percent no additional improvement can be ascertained. Usually, the concentration of the powdering agent will be in a practical optimum range from about 6 weight percent to about 10 weight percent.

The powdering agent functions under the conditions of this invention to subdivide the lime soap mass at least in the presence of the extraction solvent into small discrete particles and ideally into a frangible powder. The reasons why the powdering agent functions this way are not fully known. However, it is believed that the powdering agent functions through the creation of interfacial forces which tend to override the natural cohesive forces of the soap mixture. This explains the need for relatively dry soap to provide adequate wetting of the powdering agent by lipid matter. It appears possible that the abrasive quality of the inorganic powdering agent also plays a role in breaking up any lumpy material that is formed.

A preferred embodiment of the improved lime soap process of this invention is one wherein the lime soaps are formed by the metathesis of saponified deodorizer distillates with an inorganic calcium material such as a water solubie salt, for example, calcium chloride, and such as calcium oxide, calcium hydroxide or the like. In general this embodiment of the process proceeds as follows.

Crude vegetable oil deodorizer distillate, rich in unsaponifiable matter, is saponified in an alcoholic medium with an excess of an alkali which is an alkali metal tincluding ammonium) hydroxide, carbonate and the like, (preferably a 50% aqueous solution of sodium hydrox: ide). When saponification is complete, the excess alkali is neutralized with a dilute mineral acid. This provides an environment more favorable to the preservation of the tocopherols throughout the remaining steps of the process.

At this point a quantity of an aqueous solution of a calcium salt, preferably calcium chloride, is admixed with the mass. This quantity preferably represents a stoichiometric excess to the extent of about of the quantity required to convert the sodium soaps into calcium soaps. Additional monohydric alcohol, such as methanol, is added to the reaction mass. This tends to prevent emulsification which would mitigate against a clean separation of the water soluble components. The reaction mass is permitted to settle, whereupon two layers form.

The aqueous, alcoholic, salt layer containing the glycerine of saponification is decanted from the underlying layer of calcium soaps containing the unsaponifiables which, at this point, still form a relatively fluid mass. The soaps are then heated to a temperature in excess of 100 C. until any remaining alcohol is vaporized and the residual water concentration of the soap mass is less than about five weight percent.

The inorganic powdering agent is then admixed with the still fluid soap mass.

The soap mass may then be subjected to further heat and vacuum to drive off the remaining volatile matter. At this point, the soaps may become rather tacky but upon addition of the extraction solvent, the tacky mass soon disintegrates into a friable powder.

An extraction solvent, preferably acetone, is admixed with the soap mass-powdering agent mixture, forming a slurry. The unsaponifiable matter is released from the mixture and dissolved in the solvent.

The extracted slurry is then filtered (readily) through a pressure or suction filter and the filter cake treated with fresh solvent to remove occluded unsaponified matter by insing, repulping and reextraction or by both of these methods.

The combined extract and washes are concentrated as by solvent distillation and wintered at low temperatures in order to crystallize the sterols. The crystallized sterols are then readily removed by filtration to give a high purity sterol fraction and in the filtrate a high potency tocopherol fraction.

The original mare containing the powdering agent and calcium soaps is then acidulated with dilute mineral acid, for example, hydrochloric acid, in order to generate a high purity fatty acid fraction relatively free of unsaponifiables. The aqueous layer from the acidulation containing in solution the calcium salt of the mineral acid, for example, calcium chloride, can be filtered to recover for reuse the undissolved powdering agent.

In another preferred embodiment of the improved lime soap process of this invention the lime soaps are formed directly. In this embodiment either calcium oxide and at least a stoichiometric quantity of water or calcium hydroxide plus a small amount of water are admixed with the crude vegetable oil deodorizer distillate and the mixture heated to about 200 C. for a suitable reaction time, for example, 1 hour in an enclosed reaction vessel under elevated pressure. At the end of the reaction time the reaction mass is brought to atmospheric pressure and, if necessary, excess moisture evaporated to establish the moisture concentration of the reaction mass at less than about five weight percent. The inorganic powdering agent is then admixed with the reaction mass. Extraction and work-up of the extract and mare is then done in the same fashion as in the case of the metathesis embodient of this invention.

Various concepts, advantages and features of this invention are presented in the following examples. In this regard these examples are illustrative and not restrictive.

Example 1 This example illustrates the application of the concepts of this invention to the metathesis embodiment of the lime soap process.

300 grams of soybean oil deodorizer distillate having a 12.3 weight percent total tocopherol content as ascertained by Emmerie-Engel assay, approximately 17 weight percent total sterol content as determined by infrared assay and having a saponification number of 119 were dissolved in 230 milliliters of methyl alcohol in a stirred reactor and heated to reflux temperature. After air had been expelled from the reactor and while the solution was under reflux, 67 grams of 48% aqueous sodium hydroxide were gradually added to the reactor contents. Saponification resulted. Reflux conditions were continued for approximately 1 hour to complete the saponification. 13.2 milliliters of 37% hydrochloric acid were then added to the saponified mixture to neutralize the excess sodium hydroxide.

A solution containing 51 grams of calcium chloride, 200 milliliters of water and 700 milliliters of methyl alcohol was then stirred into the saponified mixture. Immediately a thick, creamy layer of calcium soaps formed on the bottom of the reactor containing the mixture. A relatively clear alcohol and water layer formed on top of the calcium soaps layer. The alcohol and water layer containing glycerin, sodium chloride and excess calcium chloride was removed by decantation.

The remaining soap mass was dried to a moisture concentration less than about 5 weight percent by stirring and heating to a temperature of 100 C. at atmospheric pressure.

At this point 10 grams of colloidal calcium silicate, commerically available under the proprietary designation of Microcel C were stirred into the still fluid soap mass. The mixture was heated under vacuum with stirring to remove the last visible traces of alcohol and water. This resulted in the soap mixture becoming solid due to evaporative cooling. The vacuum was broken with nitrogen and 1 liter of boiling acetone added. In approximately 5 minutes the solid soap mixture disintegrated into small particles. The boiling acetone-soap mixture was stirred for 1 hour. The resulting slurry was cooled slightly and then filtered on a Biichner type filter with moderate suction. The filter cake was rinsed in situ with a small amount of hot acetone and reextracted once more with 1 liter of boiling acetone to remove the last traces of unsaponifiable material.

The actone extracts were combined, concentrated by distillation to a volume of 600 milliliters and chilled overnight to a temperature of 20 C. whereby a sterol fraction crystallized. The crystalline sterol fraction was removed by filtration and then dried, weighed and analyzed. There were 43 grams dry weight of pure white crystalline solids assaying by infrared by weight free sterol. This represents 78% by weight of the input sterols.

The filtrate was distilled to give a tocopherol concentrate. The concentrate was weighed and analyzed. There were 63.8 grams of concentrate assaying by the Emmeric- Engel assay method 51 weight percent tocopherol. This represents a yield of 88.3%.

The mare was acidulated with an excess of sulfuric acid. An oil layer and a water layer formed. Analysis of the oil layer showed an acid value of 180, 3.5 Weight percent total sterols as determined by infrared assay and 0.1 weight percent tocopherol as determined by Emmeric- Engel assay.

Example 2 This example illustrate the improvement obtained by employing a powdering agent accordance with this invention in the lime soap process.

300 grams of soybean oil deodorized distillate were saponified, neutralized and converted to lime soaps as in Example 1. The wet soaps were dried to a moisture content less than about 5 weight percent by heating to a temperature of 100 C. and then placed under vacuum. The resultant mass became solid in appearance.

1 liter of boiling acetone was added to the plastic soap mass and stirred under reflux conditions. A large soap ball formed under the action of the stirring device and there was no evidence of break-up of the soap mass even after continuous stirring and refluxing of the acetone for a period of 30 minutes.

20 grams of Microcel C colloidal calcium silicate were added to the reactor contents. Immediately the plastic soap ball began to break up and after minutes was completely disintegrated.

The resulting slurry was stirred in the acetone for 1 hour. The slurry was then filtered and reextracted twice, using 1 liter of boiling acetone for each extraction. From this point on the filtrate or micella was treated as in Ex ample 1. There resulted 37.5 grams of pure white sterols (99% pure by infrared analysis) at a yield of 71%, 62 grams of tocopherol concentrate (51% pure by Emmeric- Engel response) representing a yield of 85.6% and an acidulated mare with an acid value of 198 with the unsapcnifiables comprising mainly 4.5 weight percent sterols and 0.4 weight percent tooopherol.

Example 3 This example illustrates the eifect of too much water being present in the lime soap mass upon the addition of the powdering agent.

300 grams of soybean oil deodorizer distillate were saponified, neutralized and converted to lime soaps as in Example 1. The lime soaps were partially dried by heating to a temperature of 100 C. without employing vacuum degassing. The soaps at this point were found to still contain 6.3 weight percent volatile matter, mostly water. 1 liter of boiling acetone was added to the mass. 28 grams of Microcel C colloidal calcium silicate was added and the mixture stirred. The soaps soon turned to a heavy grease with was very difiicult to stir, tended to stick to the sides of the reactor and to ball up on the stirring device. Additional Microcel C colloidal calcium silicate was added until appreciable breakup of the soap mass was observed. This amounted to about 60 grams of calcium silicate. This partial breakup resulted in rather large agglomerated particles which were not efficiently extracted.

Example 4 This example illustrates the fact that in the procedure of Example 3, if there is too much moisture present, it makes no difference in the end result if the powdering agent is added before or after the selective solvent.

The procedure of Example 3 was repeated except that that 20 grams of Microcel C colloidal calcium silicate were first added to the partially dried lime soaps and then 1 liter of boiling acetone was added. The same results were obtained as in Example 3.

Thus, there is provided an improved lime soap excess especially useful for recovering tocopherols and sterols from vegetable oil deodori-der distillates and the like having a high concentration of unsaponifiable matter. By the lime soap process of this invention lime soaps are obtained which are readily extractable with a selective solvent in ordinary processing equipment with a better yield of tocopherols and sterols with few selective solvent extractions and less selective solvent consumption.

Other advantages, features and embodiments will be readily apparent to those in the exercise of ordinary skill in the art upon reading the foregoing specification. In

6 this regard all embodiments of this invention including variations and modifications thereof embracing the spirit and essential characteristics of this invention are within the scope of the claimed subject matter unless expressly excluded by claim langauge.

We claim:

1. In the lime soap process for treating vegetable oil deodor-izer distillates and the like to recover unsaponifiable matter including sterols and tocopherols therefrom, wherein a lime soap mass containing said unsaponifiable matter is formed and then extracted with a selective solvent in which the lime soaps are insoluble and the unsaponifiable matter is soluble, the improvement which comprises: introducing into said lime soap mass before it sets into a hard gel a powdering agent in a quantity sufficient to cause break-up of said mass upon extraction with said solvent, said powdering agent being a finely divided, oil absorbent, abrasive, inorganic solid insoluble in said solvent and inert relative to the components of the lime soap mass.

2. In the lime soap process for treating Vegetable oil dcodonizer distillates and the like to recover unsaponifiable matter including sterols and tocopherols therefrom, wherein a lime soap mass containing said unsaponifiable matter is formed and then extracted with a selective solvent in which the lime soaps are insoluble and the unsaponifiable matter is soluble, the improvement which comprises: establishing and maintaining the moisture content of said li-me soap mass below about five percent by weight; and admixing with the lime soap mass before it sets into a hard gel at powdering agent selected from the group consisting of colloidal calcium silicate, colloidal sodium siiico-aluminate, finely divided alumina, colloidal silica and colloidal titania, the concentration of said powdering agent in said mass being in a range from about 3 percent by weight to about 21 percent by weight.

3. in the lime soap process for treating vegetable oil deodorizer distill-ates and the like to recover unsaponifiable matter including sterols and tocopherols therefrom, wherein a lime soap mass containing said unsaponifiable matter is formed and then extracted with a selective solent in which the lime soaps are insoluble and the unsaponifiable matter is soluble, the improvement which comprises: establishing and maintaining the moisture content of said lime soap mass below about five percent by weight; and admixing with the lime soap mass before it sets into a hard gel a powdering agent selected from the group consisting of colloidal calcium silicate, colloidal sodium silico-aluminate, finely divided alumina, colloidal silica and colloidal titania, the concentration of said powdering agent in said mass being in a range from about 6 percent by weight to about 10 percent by weight.

4. in the lime soap process for treating vegetable oil deodorizer distillates and the like to recover unsaponifiable matter including sterols and tocopherols therefrom, wherein a lime soap mass containing said unsaponifiable matter is formed and then extracted with a selective solvent in which the lime soaps are insoluble and the unsapon-ifiable matter is soluble; the improvement which comprises: establishing and maintaining the moisture content of said lime soap mass below about five percent by weight; and admixing with the lime soap mass before it sets into a hard gel colloidal calcium silicate, the concentration of said colloidal calcium silicate in said mass being in a range from about 6 percent by weight to about 10 percent by weight.

5. A process for treating a vegetable oil deodorizer distillate and the like to recover sterols and tocopherols therefrom, which comprises: saponifying saponifiable matter in said distillate with an alkali; admixing with the saponified matter an inorganic calcium material whereby a lime soaps mass is formed; removing from the lime soaps mass water-soluble matter and suflicient water to establish the lime soaps mass at a water concentration less than about five weight percent; admixing with the 2,, lime soaps mass while still fluid a powdering agent selected from the group consisting of colloidal calcium silicate, colloidal sodium silico-aluminate, finely divided alumina, colloidal silica and colloidal titania, the concentration of said powdering agent in said lime soaps mass being in a range from about 3 weight percent to about 21 weight percent; admixing with the lime soaps mass-powdering agent mixture a selective solvent in which the lime soaps are insoluble and sterols and tocopherols are soluble whereby a solvent solution of said sterols and tocopherols is formed; separating said solution from said mixture; and recovering powdering agent from said mixture.

6. A process for treating a vegetable oil deodorizer distillate and the like to recover sterols and tocopherols therefrom, which comprises: saponifying saponifiable matter in said distillate with sodium hydroxide; admixing with the saponified matter an aqueous solution of a calcium salt whereby a lime soaps mass is formed; removing from the lime soaps mass water-soluble matter and sulficient water to establish the lime soaps mass at a water concentration less than about five weight percent; admixing with the lime soaps mass while still fluid colloidal calcium silicate, the concentration of said colloidal calcium silicate in said lime soaps mass being in a range from about 3 Weight percent to about 21 weight percent; admixing with the lime soaps mass-colloidal calcium silicate mixture a selective solvent in which the lime soaps are insoluble and sterols and tocopherols are soluble whereby a solvent solution of said sterols and tocopherols is formed; separating said solution from said mixture; and

removing solvent from said solution whereby a concentrate of sterols and tocopherols is obtained.

7. A process for treating a vegetable oil deodorizcr distillate and the like to recover sterols and tocopherols therefrom, which comprises: saponifying saponifiable matter in said distillate with sodium hydroxide; admixing with the saponified matter an aqueous solution of calcium chloride whereby a lime soaps mass is formed; removing from the lime soaps mass water-soluble matter and sufficient water to establish the lime soaps mass at a water concentration less than about five weight percent; admixing with the lime soaps mass while still fluid colloidal calcium silicate, the concentration of said colloidal calcium silicate in said lime soaps mass being in a range from about 3 weight percent to about 21 weight percent; admixing with the lime soaps mass-colloidal calcium silicate mixture a selective solvent in which lime soaps are insoluble and stero-ls and tocopherols are soluble whereby a solvent solution of said sterols and tocopherols is formed; separating said solution from said mixture; and recovering colloidal calcium silicate from said mixture by aciditying said mixture with a dilute mineral acid whereby there is formed a fatty acid fraction and an aqueous fraction and separating from said aqueous fraction said colloidal calcium silicate.

References Cited in the file of this patent UNITED STATES PATENTS

Claims (1)

1. 2. IN THE LIME SOAP PROCESS FOR TREATING VEGTABLE OIL DEODORIZER DISTILLATES AND THE LIKE TO RECOVER UNSAPONIFIABLE MATTER INCLUDING STEROLS AND TOCOPHEROLS THEREFROM, WHEREIN A LIME SOAP MASS CONTAINING SAID UNSAPONIFIABLE MATTER IS FORMED AND THEN EXTRACTED WITH A SELECTIVE SOLVENT IN WHICH THE LIME SOAPS ARE INSOLUBLE AND THE UNSAPONIFIABLE MATTER IS SOLUBLE, THE IMPROVEMENT WHICH COMPRISES: ESTABLISHING AND MAINTAINING THE MOISTURE CONTENT OF SAID LIME SOAP MASS BELOW ABOUT FIVE PERCENT BY WEIGHT; AND ADMIXING WITH THE LIME SOAP MASS BEFORE IT SETS INTO A HARD GEL A POWDERING AGENT SELECTED FROM THE GROUP CONSISTING OF COLLOIDAL CALCIUM SILICATE, COLLODIAL SODIUM SILICO-ALUMINATE, FINELY DIVIDED ALUMINA, COLLOIDAL SILICA AND COLLOIDAL TITANIA, THE CONCENTRATION OF SAID POWDERING AGENT IN SAID MASS BEING IN A RANGE FROM ABOUT 3 PERCENT BY WEIGHT TO ABOUT 21 PERCENT BY WEIGHT.