US3335154A - Separation of tocopherols and sterols from deodorizer sludge and the like - Google Patents

Description

United States Patent Office 3,335,154 Patented Aug. 8, 1967 3,335 154 SEPARATION OF TOCUPl'iEROLS AND STEROLS FROM DEODORIZER SLUDGE AND THE LIKE Frank E. Smith, Rochester, N.Y., assignor to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey No Drawing. Filed June 4, 1963, Ser. No. 285,238 2 Claims. (Cl. 260-345.6)

This invention relates to the chemical arts. More particularly, it relates to the problem of separating tocopherols and sterols from deodorizer sludge and the like.

'Iocopherols and sterols are complex alcohols of wellknown utilities. a-Tocopherol and its esters are employed in vitamin preparations because of their vitamin E actiivty whereas the non-a-tocopherols are useful as intermediates for making a-tocopherol. The sterols are useful as raw materials in the preparation of such medicinals as cortisone and sex hormones as well as starting materials in the synthesis of other pharmaceutical products.

Tocopherols and sterols are,found in natural fats and oils and particularly in vegetable oils. When such fats and oils are subjected to conventional deodorizer treatment, that is, blown with an inert gas such as steam, nitrogen and the like under vacuum, a by-product material usually separates from the inert gas in traps, condensers and the like. This by-product material is commonly referred to as deodorizer sludge. It is also termed deodorizer distillate, hot well scum, lighter-than-water scum, clabber stock, condenser oil, deodorizer trap oil, catch basin scum and the like. Invariably the tocopherols and sterols of the oil and fat being deodorized are found to be concentrated in this deodorizer sludge. However, the tocopherols and sterols are usually present in the sludge in a very complex mixture. This mixture comprises tocopherols, sterols, sterol esters, glycerides, free fatty acids, hydrocarbons and other materials. Hence, to separate tocopherols and sterols from deodorizer sludge, rather involved chemical and physical treatments must be employed. One general type of process for separating tocopherols and sterols from deodorizer sludge, which is referred to herein as the esterification process, involves the conversion of tocopherol esters, sterol esters and glycerides to the tocopherols, sterols and glycerol, and the esterification of the free fatty acids (as well as the fatty acid moieties resulting from the conversion) with a lower, monohydric, aliphatic alcohol. The resulting esters can be readily removed by distillation in a subsequent step from the much higher boiling, free tocopherols.

One embodiment of the esterification process is disclosed by Brokaw in British patent specification 774,855. This embodiment involves the steps of saponification, acidulation and esterification.

The deodorizer sludge is initially saponified by the addition of caustic soda in order to free the sludge of fatty acid esters.

The saponified deodorizer sludge is then acidulated with a mineral acid such as sulfuric acid whereby there results a mixture of free fatty acids, free tocopherols, free sterols, glycerol, water, excess mineral acid 'and alkali salts. The glycerol and water with the excess acid and salts in solution separate from the oily mixture and are usually removed therefrom.

The oily mixture is thereafter treated so as to convert unesterified, free fatty acids to lower boiling fatty acid esters. This involves admixing an esterification catalyst, for example, a mineral acid such as hydrochloric acid, and a lower monohydric, aliphatic alcohol such as methanol, with the oily mixture and refluxing until substantially the entire free fatty acid content is esterified. Usually the lower monohydric alcohol added to the mixture is in stoichiometric excess relative to the free fatty acids. The resulting esterification reaction mixture usually comprises free tocopherols, free sterols, excess lower, monohydric, aliphatic alcohol, lower, monohydric, aliphatic alcohol esters of fatty acids, water formed in the reaction and the esterification catalyst. At this point most, if not all, of the lower, monohydric, aliphatic alcohol is distilled off from the reaction mixture. Because of the presence of the esterification catalyst and because as distillation proceeds, the concentration of methanol in the reaciton mixture decreases, sterol ester formation by reaction of free sterols with fatty acid esters tends to be promoted. As a consequence, after further treatment steps to separate the mixture into its components, there is obtained (1) a tocopherol concentrate having a significant, undesired, concentration of sterol esters and (2) a free sterols product representing a yield substantially less than the theoretical maximum. Consequently, there is a real need for the improvement of this saponification, acidulation and esterification embodiment so as to reduce the sterol ester formation.

Another embodiment of the esterification process for treating deodorizer sludge and the like to separate sterols and tocopherols therefrom is disclosed in the US. Patent No. 2,704,764, to Mattikow et al. In this embodiment there is employed a concurrent splitting and esterification step. This step is performed by admixing the deodorizer sludge with a lower, monohydric, aliphatic alcohol such as methanol, preferably in stoichiometric excess relative to the fatty acid moieties content of the sludge, and a mineral acid such as sulfuric acid, under reflux conditions. An esterification reaction mixture is thereby obtained, which consists essentially of free tocopherols, free sterols, excess lower, monohydric, aliphatic alcohol, fatty acid estersof the lower, monohydric, aliphatic alcohol, water, glycerol and mineral acid. At this point some of the sterols, but not all, are removed from the reaction mixture. Thereafter, most, if not all, of the free, lower, monohydric, aliphatic alcohol is distilled from the esterification reaction mixture and the remaining mixture is treated further to separate therefrom substantially all of the free tocopherols and free sterols. This procedure likewise results in a tocopherols concentrate having a significant concentration of sterol esters and in a free'sterols product at less than maximum yield. Hence, there is a real need for improvement of this concurrent splitting and esterification process to minimize the formation therein of sterol esters.

An object of this invention is to provide an improved esterification process for the separation of tocopherols and sterols from deodorizer sludge and the like.

A specific object of this invention is to provide an esterification process for treating deodorizer sludge and the like whereby a tocopherol concentrate without a significant sterol ester content is obtained.

Another specific object of this invention is to provide such a process wherein yield of free sterols is substantially at the theoretical maximum.

Another object of this invention is to provide an improved esterification process which does not require additional equipment or materials.

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

In summary, this invention comprises an improved esterification process for the separation of tocopherols and sterols from deodorizer sludge whereby a purer tocopherols concentrate and a higher yield of sterols are obtained. In the process of this invention, an esterification react-ion mixture is formed as before from the deodorizer sludge. However, instead of removing excess lower, monohydric, aliphatic alcohol therefrom, substantially all of the free sterols are separated from the esterification reaction mixture under conditions which minimize the formation of sterol esters.

In the more specific aspects of this invention substantially all of the sterols are removed from the esterification reaction mixture by introducing sufiicient water into it to give a'resulting water concentration in the range from about 5 to about 60% by weight of the watered mixture. Preferably the temperature of the watered mixture is established and maintained in a range from about C. to about 40 C. whereby substantially all of the sterols in the watered-mixture crystallize. These crystallized sterols are then separated from the watered mixture. There remains a substantially sterol free mixture comprising an aqueous phase consisting essentially of water, lower monohydric alcohol, esterification catalyst and glycerol, and an oil phase consisting essentially of tocopherols and lower, monohydric alcohol esters of fatty acids. Preferably, the oil phase is separated from the aqueousphase to give a high purity tocopherols concentrate substantially free of sterol esters.

In a preferred specific embodiment of this invention deodorizer sludge, rich in sterols and tocopherols, is, as taught in the British patent specification 774,855, saponified, acidulated and then esterified with a lower, monohydric, aliphatic alcohol present in stoichiometric excess relative to the fatty acid moieties content of the sludge. As soon as possible after completion of the esterification reaction step and prior to removal of any of the lower alcohol, water is added to the esterification reaction mixture. Preferably the water concentration in the watered mixture is in a range from about weight percent to about 60 weight percent. The water added to the reaction mixture may be either hot or cold. Preferably it is cold in order to minimize the amount of heat to be removed-subsequently from the watered reaction mixture for the crystallization of the sterols. The watered mixture is then cooled, as by refrigeration, to room temperature where-' upon an emulsion of sterols, a water-alcohol phase and an oil phase forms.

At this point residual mineral acid (from the esterification step) in the emulsion should be neutralized with a suitable alkali, for example, sodium bicarbonate, in order to protect subsequent processing equipment.

The emulsion is then subjected to a solids separation operation, for example, centrifugation or filtration, to remove the sterol crystals. This results in an immediate separation or break-out of oil and water-alcohol phases in the filtrate. These phases are readily separated and removed from one another. The residual lower alcohol can now be, and preferably is, safely distilled or washed away from the oil in view of the fact that substantially all of the sterols have been removed in the filter cake.

The filter cake contains a substantial concentration of occluded material which can be removed by washing or rinsing the cake with-a lower, monohydric, aliphatic alcohol, for example, methanol, or with a solvent mixture, for example, a rinse medium consisting of approximately 76 weight percent acetone, 19 weight percent methanol and 5 weight percent water.

The oils from the rinse and from the filtrate are combined and subjected to molecular distillation to strip off the low boiling lower alcohol esters, leaving as a residue a high potency tocopherol concentrate. This concentrate is substantially free of saponifiable matter other than lower alcohol esters of higher molecular weight fatty acids since there is substantially no sterols present in the distillation procedure to enter into interesterification reaction.

The filter cake from this operation, after drying, is a White crystalline sterol product of reasonably high purity which can be easily upgraded to a pharmaceutical grade or purity by recrystallization or by extraction with solvents.

The process makes possible the production of a high potency tocopherol concentrate by a shorter and a more direct route than has heretofore been possible. The expensive step of solvent wintering or its equivalent as employed in the prior art processes to separate sterols is eliminated, thereby reducing considerably the amount of in-process inventory and intermediate storage periods during which tocopherols deteriorate- Shortening the procedure and eliminating this unnecessary handling results in a substantial improvement in the yield of tocopherols. As an added bonus there is obtained a high yield of valuable by-product sterols of good grade which can be con-- verted to pharmaceutical grade as by the simple expedient of extracting with hexane.

This invention is further illustrated by the following examples of specificembodiments of the prior art process and of this invention. This invention is not limited to the specific embodiments of the invention described in these examples unless otherwise expressly indicated.

Example 1 I This example illustrates the saponification, acidulation' tion number of 106.5 were dissolved in 10 liters of methanol and saponified for one hour with 1.9-6 kilograms of 50% caustic soda. The resulting soaps were acidulated and partially esterified by adding to the saponification reaction mass 2.55 liters of 37% hydrochloric acid and refluxing for 1 hour. Under quiescent conditions an aqueous layer of salt, glycerine and methanol formed underneath the oily reaction mixture. After withdrawing this aqueous salt-glycerine-methanol layer, an additional 5.4 liters of methanol and 0.14 liter of concentrated hydrochloricacid were added and the mixture refluxed for 1 hour to drive the esterification to completion.

The methanol was then distilled off from the esterification reaction mixture at a temperature of C. and the alcohol depleted reaction mixture given three hot water washes to remove the mineral acid. The resulting 7 wintered from acetone in several parts by dissolving 20.

gram portions thereof in '80 milliliters acetone, chilling to 20 C., and filtering. The filter cakes were combined to produce 1111.3 grams of sterol cake assaying 81.5 weight percent free sterols by infrared analysis. This represents an over-all sterol recovery of 753% based on the infrared input analysis of the distillate or 60.0% based on the Lieberman and Burchard assay method of the deodorizer distillate.

The filtrates from the wintering operation were combined, giving 1110.04 grams of tocopherol concentrate. The concentrate assayed 490 milligrams of tocopherol per gram of concentrate, representing an over-all yield of tocopherols of 79.2%.

Example 2 This example illustrates the improvements obtained in accordance with this invention.

kilograms of the identical deodorizer distillate employed in Example 1 where saponified, accidulated and esterified as in Example 1. The esterification reaction mixture was drawn off from the esterification reactor and stored without removing any of the methanol.

An aliquot part of the esterification reaction mixture, representing 684 grams of the original deodorizer distillate, was reheated and stirred with 940 milliliters of cold water. The mixture was further cooled with refrigeration 'to a temperature of C. and the resulting emulsified mixture centrifuged in an 8 inch basket centrifuge. The centrifuge cake was rinsed with 500 milliliters of a rinse medium composed of 76 weight percent acetone, 19 weight percent methanol and 5 weight percent water, and chilled to 15 C. The wet centrifuge cake weighed 167 grams and contained 9% rinse medium. Upon drying this cake, a white crystalline sterol product was obtained which assayed by infrared analysis 84 weight percent free sterols, and 11 weight percent methyl esters. This represents a free sterol yield of 97% based on the infrared analysis of the deodorizer distillate and 78% based on Lieberman and Burchard analysis of the deodorizer distillate.

100 grams of the wet cake were recrystallized once from 800 milliliters of acetone at C. to give 76.6 grams of sterols, 97.5 weight percent pure at an over-all yield of 95% at this stage of purification based on infrared assay. This yield of sterols is a substantial improvement over that (75.3%) of Example 1.

The filtrate from the centifuge broke out or separated immediately into a clear water-methanol layer and an oil layer, which layers were separated by decantation. The oil layer was degassed with heat and vacuum. There resulted 440 grams of dry oil. Infrared analysis showed that the dry oil contained only 1 weight percent sterols. The oil recovered from the filter cake rinse amounted to 71 grams dry weight. 449 grams of the combined filtrate and filter cake rinse oil were stripped in a 5 inch cyclic molecular still. The residue, a tocopherol concentrate, weighed 103.6 grams and had an Emmerie-Engle assay of 506 milligrams of tocopherols per gram. This represents an over-all yield of tocopherols of 79.5%.

Example 3 This example further illustrates the improvement obtained by this invention.

Another aliquot part of the esterification reaction mixture of Example 2, taken before any removal of methanol and representing 663 grams of original deodorizer distillate was reheated to reflux temperature and then stirred 'with 940 milliliters of cold water. The mixture was further cooled to 30 C. by refrigeration and then centrifuged and rinsed with the rinse medium as in Example 2. The wet centrifuge cake weighed 164.0 grams and contained 146.0 grams of dry crystals. The dry crystals assayed by infrared analysis 85.5 weight percent free sterols and 11.5 weight percent methyl esters. This represents a free sterol yield of 98.0% (of. 75.3% of Example 1) based on the infrared assay of the deodorizer distillate or 79% (of. 60.0% of Example 1) based on the Lieberman and Burchard assay of the deodorizer distillate.

498.0 grams of residue were obtained after distilling 01f the methyl alcohol and rinse solvent from the combined filtrate and rinse. 428 grams of this residue were stripped in a 5 inch cyclic molecular still to yield 113 grams of concentrate. An Emmerie-Engel assay showed the concentrate to have a tocopherol potency of 480 milligrams per gram. There was infrared evidence of 8 weight percent free sterols in this concentrate and no infrared evidence of sterol esters. This indicates that hydrolysis of the sterols remained complete throughout the entire process of sterol separation.

Thus there is provided an improved process for the separation of sterols and tocopherols free from deodorizer sludge and the like.

Other embodiments, advantages and features will be apparent to those in the exercise of ordinary skill in the art upon reading the foregoing disclosure. In this regard, all embodiments of this invention including variations and modifications thereof embracing the spirit and essential characteristics of this invention are included in the scope of the claimed subject matter unless expressly excluded by claim language.

This application is a continuation-in-part of the US. patent application Ser. No. 114,018, filed June 1, 1961, for Separation of Tocopherols and Sterols From Deodorized Sludge and the Like.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In a process for separating sterols and tocopherols from deodorizer sludge wherein an esterification reaction mixture is obtained which consists essentially of an esterification catalyst, water, sterols, tocopherols, a lower, monohydric, aliphatic alcohol and fatty acid esters of said alcohol, the improvement which comprises: separating substantially all of said sterols from said reaction mixture without prior distillation of said reaction mixture by admixing suflicient water with said reaction mixture in the presence of said alcohol to give a watered mixture having a water concentration in the range from about 5 to about 60% by weight of said watered mixture, establishing and maintaining the temperature of said watered mixture in a range from about 0 C. to about 40 C., whereby substantially all of said sterols in said water mixture crystallize, and removing substantially all of said crystallized sterols from said watered mixture, whereby there remains a two phase mixture comprising an aqueous phase consisting essentially of water, said alcohol and said esterification catalyst, and an oil phase consisting essentially of said tocopherols and said fatty acid esters of said alcohol; separating said oil phase from said aqueous phase; and removing from said oil phase said esters whereby a high purity tocopherols concentrate is obtained.

2. In a process for separating sterols and tocopherols from deodorizer sludge, which process comprises the steps of saponification, acidulation and esterification, whereby an esterification reaction mixture is obtained which consists essentially of a mineral acid esterification catalyst, water, sterols, tocopherols, a lower, monohydric, aliphatic alcohol and fatty acid esters of said alcohol, the improvement which comprises: separating substantially all of said sterols from said reaction mixture without prior dis-' tillation of said reaction mixture by admixing sufiicient water with said reaction mixture in the presence of said alcohol to give a watered mixture having a water concentration in the range from about 5 to about 60% by weight of said watered mixture, establishing and maintaining the temperature of said watered mixture in a range from about 0 C. to about 40 C., whereby substantially all 'of said sterols in said watered mixture crystallize, neutralizing said watered mixture, and removing substantially all of said crystallized sterols from said Watered mixtures whereby there remains a two phase mixture comprising an aqueous phase consisting essentially of water, said alcohol and said esterification catalyst, and an oil phase consisting essentially of said tocopherols and said fatty acid esters of said alcohol, solvent washing said sterol crystals and separating the solvent therefrom; separating said oil phase from said aqueous phase; com- 8 bining said separated solvent with said oil phase; and re- FOREIGN PATENTS moving from said oil phase said esters whereby a high 774 855 5/1957 Great Britain purity tocopherols concentrate is obtained.

WALTER A. MODANCE, Primary Examiner.

References Cited 5 2,704,764 3/1955 Mattikow 260-345.6 NORMA s. MILESTONE, NORM STEPNO;

Assistant Examiners.

2,715,639 8/1955 Albrecht et a1. 260-39725

Claims (1)

1. IN A PROCESS FOR SEPARATING STEROLS AND TOCOPHEROLS FROM DEODORIZER SLUDGE WHEREIN AN ESTERIFICATION REACTION MISTURE IS OBTAINED WHICH CONSISTS ESSENTIALLY OF AN ESTERIFICATION CATALYST, WATER, STEROLS, TOCOPHEROLS, A LOWER, MONOHYDRIC, ALIPHATIC ALXOHOL AND FATTY ACID ESTERS OF SAID ALCOHOL, THE IMPROVEMENT WHICH COMPRISES: SEPARATING SUBSTANTIALLY ALL OF SAID STEROLS FROM SAID REACTION MIXTURE WITHOUT PRIOR DISTILLATION OF SAID REACTION MIXTURE BY ADMIXING SUFFICIENT WATER WITH SAID REACTION MIXTURE IN THE PRESENCE OF SAID ALCOHOL TO GIVE A WATERED MIXTURE HAVING A WATER CONCENTRATION IN THE RANGE FROM ABOUT 5 TO ABOUT 60% BY WEIGHT OF SAID WATERED MIXTURE, ESTABLISHING AND MAINTAINING THE TEMPERATURE OF SAID WATERED MIXTURE IN A RANGE FROM ABOUT 0*C. TO ABOUT 40*C., WHEREBY SUBSTANTIALLY ALL OF SAID STEROLS IN SAID WATER MIXTURE CRYSTALLIZE, AND REMOVING SUBSTANTIALLY ALL OF SAID CRYSTALLIZED STEROLS FROM SAID WATERED MIXTURE, WHEREBY THERE REMAINS A TWO PHASE MIXTURE COMPRISING AN AQUEOUS PHASE CONSISTING ESSENTIALLY OF WATER, SAID ALCOHOL AND SAID ESTERIFICATION CATALYST, AND AN OIL PHASE CONSISTING ESSENTIALLY OF SAID TOCOPHEROLS AND SAID FATTY ACID ESTERS OF SAID ALCOHOL; SEPARATING SAID OIL PHASE FROM SAID AQUEOUS PHASE; AND REMOVING FROM SAID OIL PHASE SAID ESTERS WHEREBY A HIGH PURITY TOCOPHEROLS CONCENTRATE IS OBTAINED.