Patented Feb. 14, 1939 2,146,894

UNITED STATES PATENT OFFICE 2,146,894 WACUUM. DSTLASGN Kenneth C. D. Hickman, Rochester, N. Y., assign or, by mesne assignments, to Distilation Prod ucts, Inc., Rochester, N. Y., a corporation of Delaware No Drawing. Application October 11, 1935, Serial No. 44,631 10 Claims. (C. 167-81) This invention relates to the purification of temperatures considerably above the boiling point organic material, especially such as contained in of the desired material must be used. Thus, in vegetable and animal oils, fats and waxes, and distilling fish oils, such as cod liver oil, the vita particularly to the removal from Such oils of mins distill Over at temperatures varying from materials of therapeutic value by vacuum distill- 140 to 220 C., the optimum temperature for 5 lation. recovery of vitamin A being about 180° C. Re Processes of high vacuum distillation are known cently nearly pure vitamin A has been secured in which difficultly volatile materials are re- and it has been found that it distills at less than moved in purer form from impurities and unde- 100° C. under molecular distillation conditions. 10 sirable admixtures. Thus in U. S. patent to It is, therefore, seen that it is necessary accord- 10 Burch 1955,321 difficultly volatile oils are vacuum ing to known processes to use a temperature of distilled to remove desired constituents therefrom. about 80 C. above the boiling point of the vita In my U. S. Patent No. 1,925,559, natural oils min to eliminate it from the distillate. and fats are vacuum distilled to concentrate com- If a material having a boiling point in the 5 pounds of therapeutic value contained therein, neighborhood of that of the desired distillate is 15 such as vitamins. added to the mixture to be distilled, it is found In such high vacuum distillation processes, due that a considerably lower temperature can be to the difficultly volatile nature of the compound used for Optimum results. Thus, on vacuum dis being purified, temperatures considerably above tilling animal and vegetable oils to concentrate the boiling point of the desired compound under fat soluble and other vitamins contained therein, 20 the vacuum obtaining must be used. A satis- the addition of a quantity of other material hav factory removal of the desired compound at tem- ing approximately the same boiling point under peratures lower than those heretofore found vacuum conditions as the desired vitamin, makes necessary is of considerable importance, since it possible to readily distill the vitamin, using a 2 5 it would result in a material saving in material much lower temperature than previously possible. 25 otherwise lost due to decomposition. The amount The use of such lower temperatures is a very of heat required to volatilize the desired material desirable feature where heat sensitive and easily would also be considerably less. decomposable materials are to be recovered. Fur The present invention has for its object to over- thermore, many of the desired distillates are solid 30 come the deficiencies of hitherto known vacuum or so viscous as to collect in the still and are 30 distillation processes for concentrating or puri- difficult to remove. The addition of a liquid ma fying materials and to provide a process whereby terial having the proper boiling point will pre such materials may be purified without undesir- vent Such clogging and make continuous oper able decomposition and with a considerable sav- ation possible. Thus, the addition of fatty acids 35 ing in time and heat energy. A further object boiling in the neighborhood of sterols being dis- 35 is to provide a process for concentrating thera- tilled from an oil prevent the solid or viscous peutic values contained in natural oils without distillate from clogging the apparatus with re undesirable decomposition or waste of heat. A Sultant delay for cleaning. still further object is to concentrate the vitamin The materials to be added may be selected from 40 and/or sterol content of animal and vegetable widely different types of compounds or mixtures 40 oils by a process of vacuum distillation which thereof. Any material may be used as long as it avoids material decomposition of the vitamins has a boiling point in the neighborhood of the and makes possible a faster rate of distillation distillate desired, under molecular distillation at a lower temperature than has previously been conditions and has no adverse effect on the ma 45 found possible. Other objects will appear herein- terial undergoing treatment. Thus, fatty acids, 45 after. esters, mineral oil fractions, terpenes, essential These objects are accomplished by the follow- oils and the like have been found to give useful ing invention which, in its broader aspects, com- results. Of course, a compound which is subject prises adding to the material to be vacuum dis- to material decomposition should not be selected. 50 tilled a compound or mixture of compounds hav- Aliphatic phthalates, benzyl phthalate, beta 50 ing a boiling point, under the distillation condi- phenyl ethyl phthalate, diglycerol tetrapropion tions obtaining, in the neighborhood of that of ate boil below vitamin A and are useful agents the material which it is desired to purify. to employ in its recovery. In order to aid in a When the materials being concentrated or clearer understanding and description of the in purified are distilled, it has been noticed that vention, the above-described materials are here- is 2 2,146,894 from these oils boils at around 140'. When, howa inafter referred to as entraining agents, although ever, it is desired to drive the vitamins off from the expression is not to be taken as an explana the parent oil, it is found that temperatures of tion of the theory of the invention, or as a limita 160 and higher are required for the D and 180° tion to agents having only that function. to 215 for the A. This is partly because the Many of the entraining agents selected are so vitamins are present in such minute quantities 5 expensive that they cannot be used without care and partly because there are only relatively small ful recovery. The distillates containing the en amounts of fatty glycerides in the oil of boiling training agent and the vitamin or other material points similar to the vitamins. The oil of Com distilled may be run through a separate still where merce is rich in the long chain fatty glycerides, 0. the vitamin or other desired material may be sep and comparatively rich in free fatty acids, but 10 arated. The entraining agent will remain as the the fatty glycerides with 8 to 14 carbon atoms still residue, if it had a higher boiling point than in the side chain are conspicuous by their ab the desired purified material, or will be in the Sence. I therefore add, for instance, to the in distillate, if it has a lower boiling point. In this coming oil four parts of glyceryl tri-pelargonate 5 way the agent can be recovered practically and I then find that distillation of a fraction rich 5 quantitatively. The agents may still contain in A and D occurs at a temperature of 160° C. Small amounts of the desired purifled material, The quantity of the fraction is about 5%. but as they are used repeatedly, being added again I may add the tri-pelargonin for another and again to the fresh material initially treated, reaSon. My researches have shown that the dis 20 this does not represent a loss. Obviously other tillation characteristics of vitamin D and choles 20 methods of separation known in the art, such as terol are very similar. The vitamin D when Ordi freezing, crystallization, Solvent extraction. Or narily eliminated has so small a bulk that it takes purely chemical means may be employed instead a long time to drain from the condensing surface of distillation for separating the entraining agent. and often suffers decomposition on the way. As previously indicated, the entraining agent With oils rich in cholesterol, the vitamin is held 25 may have a boiling point the same as, above or On the Condensing Surface in a mass of crystals. below that of the substance to be removed. Pref In melting these down, the vitamin D is volatilized erably an agent having a boiling point below that and partly destroyed. It will be appreciated that of the desired substance is used, since the lower when pelargonin or its equivalent is added, the boiling entraining agent generally gives better bulk of the condensate is increased, the crys 30 results at lower temperatures. tallization of the cholesterol is prevented, or mini As pointed out above, the invention is applicable mized, and the vitamins are swept rapidly from to any process of vacuum distillation in which a the still. difficultly volatile organic material is separated as It is not known how the agents used effect the the distillate. Thus, vitamins A, D and/or E may results described. It may be that they form 35 be separated by distillation from vegetable and azeotropic mixtures with the desired material to animal oils containing them, such as cod, halibut, be concentrated, or that they act to blow the ma etc., liver oils, menhaden, salmon, dogfish, Sword terial out in a manner similar to steam distilla fish, corn wheat germ oils and the like. Hor tion. However, it is not intended that the inven 40 mones of various types may be recovered from tion be limited to any theory as to how the en 40 oily concentrates by the present invention, as training agents effect the results of the herein may also sterols and high boiling hydrocarbons described invention. from mixtures containing them. In the claims, where the entraining liquid is The distillation may be carried out in the man defined as having a boiling point at or in the ner described in my U. S. Patents NOS. 1925,559 - neighborhood of that of the desired distillate or 45 and 1942,858. Such molecular distillation proc fraction, it is to be understood that the boiling esses are generally carried out at less than .1 mm. points will be determined under approximately and at temperatures of between 70 and 250 C. the same Vacuun as that employed in carrying out preferably between 90 and 200° C. A character the vacuum distillation. Also, since materials do istic of this type of distillation is that the vapors not always boil under high vacuum conditions, it 50 are condensed upon a surface located at a dis is to be understood that the term “boiling point' tance of less than about the mean free path of designates the analogous point of maximum rate the molecules of residual gas. Pressures of above of distillation when the vacuum is so high that .1 mm. may be used and it has been found that distillation takes place by evaporation instead of volatile materials in fish oils may be distilled at by actual boiling. 55 pressures as high at 1 mm. Since a more eco The herein described invention Constitutes a nomical removal of non-volatile constituents simple, economical and highly effective solution of takes place at pressures below .01 mm. I prefer the problem of removal by vacuum distillation of to operate at these lower pressures. However, as difficultly volatile organic Compounds and par the entraining agents used enable a rapid re ticularly of heat sensitive difficultly volatile com 60 covery of the desired materials, it is not necessary pounds from mixtures containing them. An out in many cases to operate under molecular distilla standing advantage of my process is the more tion conditions and pressures higher than those rapid distillation at lower temperatures than normally used in such processes may be em could heretofore be used and the possibility of 65 ployed. distilling solids without clogging of the apparatus. I will now describe my invention by way of ex I claim: ample as applied to a fish oil containing vitamins 1. The process which comprises adding to a fish A and D. oil containing fat soluble vitamins to be distilled, I have found in my researches that, although a liquid substance having a boiling point near 70 70 pure vitamin A is an alcohol, the vitamin A oc that of the vitamin fraction and Subjecting the curring in fish oils and highly prized for its mixture to molecular distillation. medicinal value is a mixture of esters with only 2. The process of distillation which comprises a small proportion bf the free alcohol. The al adding to cod liver oil, a liquid substance having cohol boils at about 95 and the esters at 160 to a boiling point near that of the vitamin fraction s 75 190° under a molecular vacuum. The vitamin D 2,146,894 3 to be distilled and subjecting the mixture to 7. The process which comprises adding to a molecular distillation. vegetable or animal oil containing fat soluble vita 3. The process of vacuum distillation which mins a liquid having a vapor pressure in the Comprises adding to an oil containing fat Soluble neighborhood of that of a vitamin contained in vitamins, a liquid compound having a boiling point the oil, subjecting the mixture to high vacuum 5 near that of the desired vitamin fraction under distillation and separating a distillate containing the vacuum distillation conditions and subjecting the added substance and a vitamin. the mixture to distilation at a temperature be 8. The process which comprises adding to a tween 70 and 250° C. and a pressure of less than vegetable or animal oil containing fat soluble O .1 mm. and condensing the vapor at a distance vitamins at least one liquid substance which dis O from the evaporative surface of less than the tills in maximum amounts under molecular dis mean free path of the molecules of residual gas. tillation conditions at a temperature in the neigh 4. The process of vacuum distillation which borhood of that at which a vitamin in the oil ex comprises adding to a fish oil containing fat solu hibits a maximum distillation rate and subjecting 5 ble vitamins, a liquid Substance having a boiling the mixture to molecular distillation. 15 point near that of the desired vitamin fractions 9. The process which comprises adding to a and subjecting the mixture to distillation at a vegetable or animal oil containing fat soluble temperature between 70 and 250° C. and a pres vitamins, at least One liquid which distills in maxi sure of less than .1 mm. and condensing the mum amounts at a temperature in the neighbor 20 vapors at a distance from the evaporative Sur hood of that at which a vitamin in the oil ex 20 face of less than the mean free path of the hibits a maximum distillation rate, Subjecting molecules of the residual gas. the mixture to distillation at a temperature be 5. The process of distillation which comprises tween about 70° and 250° C., at a pressure of adding to cod liver oil a liquid substance having less than about .01 mm. and condensing a dis 25 a boiling point near that of the desired vitamin tillate, containing the added liquid and a vitamin, 25 fractions and subjecting the mixture to vacuum at a distance from the evaporating surface of distillation at a temperature between 70 and 250 less than about the mean free path of the mole C. and a pressure of less than .1 mm. and con cules of residual gas. densing the vapors at a distance from the evapo 10. The process of separating substances of the 30 rative surface of less than the mean free path of class consisting of hormones, sterols and vitamin 30 the molecules of the residual gas. D from oils containing them, which comprises 6. The process which comprises adding tri adding to the oil a liquid substance having a pelargonin to an oil containing fat soluble vita boiling point near that of the hormone, sterol, mins and subjecting the mixture to distillation or vitamin D, subjecting this mixture to distilla 35 at a temperature between 70 and 250° C. and a tion under a high vacuum, and separating a 35 pressure of less than .1 mm. and condensing the distillate containing the added liquid Substance vapors at a distance from the evaporative surface and the hormone, sterol or vitamin D. of less than the mean free path of the molecules of the residual gas. KENNETEC, D, ECEMAN,