US2473154A - Production of soap from hydrogenated vegetable oils - Google Patents

Description

Patented June 14, 1949 UNITED STATES ATENT OFFICE PRODUCTION OF SOAP FROM HYDRO- GENATED VEGETABLE OILS Willy Lange and Robert nati, Ohio, assignors to Company, Ohio G. Folzenlogen, Cincin- The Procter & Gamble Ivorydale, Ohio, a corporation of 11 Claims.

This invention relates to the production of soaps from hydrogenated vegetable oils, and more particularly to the production of white or substantially white soaps which on exposure to air are substantially free of the tendency to develop a coloration sometimes referred to as pink color.

Those versed in the art are aware that white or substantially white soaps prepared from vegetable oils, such as soybean, linseed, cottonseed, and the like, after hydrogenation in the customary manner, develop the above referred to undesirable pink color when exposed to the air. In the case of soaps which have been prepared from such hydrogenated oils and which contain other color imparting ingredients the pink coloration may be partially or wholly masked or modified. In prior practices the steps of hydrolyzing the hydrogenated oils and distilling the fatty acids before conversion of same into soap have sometimes been employed in an effort to separate the fat stock from the constituent responsible for the development of the undesirable coloration. Such procedures, however, require careful fractionation in order to be successful.

We have found that the gamma form of tocopherol, which occurs in most vegetable oils in admixture with the alpha form, is the constituent directly responsible for the observed coloration. The gamma tocopherol in pure form'is a light yellow viscous oil and as such' does not contribute objectionable coloration to the oil or soap, but under the conditions existing when admixed with soap it is subject to oxidation on contact with the air to an intensely red gamma tocopherol orthoquinone compound which is directly responsible for the so-called pink coloration.

It is an object of our invention to provide a process for the treatment of vegetable oils, wherein gamma tocopherol contained in the oil is rendered inactive toward oxidation to the orthoquinone compound when soaps prepared therefrom are exposed to oxidizing conditions.

A further object is to provide a white or substantially white soap from hydrogenated gammatocopherol-containing vegetable oils.

A still further object is to provide an improved hydrogenation process for use in the hydrogenation-of vegetable oil soap stocks.

In the practice of our invention the vegetable oil which is to be subsequently converted into soap is hydrogenated to the desired iodine value with the aid of a metallic catalyst in the presence of anhydrous hydrogen peroxide, highly concentrated aqueous solutions thereof, i. e. from about Super cent to 100 per cent-H202, or an organic hydroperoxide derivative thereof of the general formula R-O-O -H wherein R. represents an organic group. The hydroperoxide may be dissolved in the oil or may be present as a finely divided suspension. When unqualified, the term hydroperoxide is hereinafter used in the generic sense to include both substantially anhydrous hydrogen peroxide (at least 90% concentration) and its organic hydroperoxide derivatives.

The use of alkali metal or organic peroxides for the visible bleaching of fats and oils is generally known, and in such bleaching processes the peroxide compound destroys the coloring constituents by oxidation and itself undergoes decomposition during the reaction. The alkali metal or organic peroxides which may be employed in such bleaching processes do not produce useful results in the control of thedevelopment of pink coloration in soaps made from vegetable oils containing gamma tocopherol. Furthermore, their substitution for the hydroperoxides used in accordance with the present invention does not inactivate the gamma tocopherol so as to prevent its subsequent oxidation to the highly colored orthoquinone compound.

Moreover although treatment of hydrogenated or unhydrogenated vegetable oils containing gamma tocopherol with hydroperoxides under conditions normally employed for visible bleaching may effect some reduction in color, such treatment does not render the gamma tocopherol inactive to oxidation when soaps prepared from the hydrogenated oil are exposed to air. Complete inactivation of the gamma tocopherol is observed only when the hydroperoxide is present during treatment of the oil with hydrogen in the presence of a metallic hydrogenation catalyst under conditions effecting a reduction in the iodine value of the oil due to absorption of the hydrogen. If the hydroperoxide is added to the oil and the mixture is heated either in the presence or absence of hydrogen without a metallic hydrogenation catalyst, the development of a pink coloration in soaps prepared from oils so treated is not avoided.

Any hydroperoxide which is soluble in the vegetable oil, or which may be incorporated therewith in the form of a fine dispersion, may be used to accomplish the objects of the present invention. However, it will be understood that in the practical application of the invention only those hydroperoxides which are commercially available and which are sufiiciently stable during storage are preferred. For example, methyl hydroperoxide is operative in the practice of the present invention, but is a-very unstablecompound and therefore quite dangerous for use on a large scale.

It is to be understood also that the stage of processing at which the hydroperoxide is added to the vegetable oil is not a limitation of the invention, but the characteristics of the hydroperoxide will determine to a large extent the stage of processing at which it may be most advantageously added. For example, since it is essential that the hydroperoxide be present during treatment of the oil with hydrogen and a metallic hydrogenation catalyst under conditions which favor absorption of hydrogen, it obviously is impractical to add the hydroperoxide in a preceding processing step if it is rendered inactive or physically removed. Thus it would be impractical to add to the crude vegetable oil prior to alkali refining a hydroperoxide such as tertiary butyl hydroperoxide which is appreciably soluble in aqueous solutions or hydroperoxides which are decomposed by refining reagents. However, certain organic hydroperoxides such as fat hydroperoxides are oil soluble and unaffected during the alkaline refining process. Such fat hydroperoxides may be produced, for example, in the crude oil itself by subjecting the vegetable oil to careful oxidation with air or gaseous oxygen to produce sufficient fat hydroperoxide in the oil to inhibit the formation of pink coloration in the soap ultimately produced from the refined, hydrogenated oil. Thus the step at which hydroperoxides may be added to the oil or produced in the oil depends upon the stability of the hydroperoxide during refining, bleaching, filtration, or other preceding processing step and/or on its solubility in the refining, bleaching or other agent used therein. Obviously the preferred procedure is to add or form the hydroperoxide just prior to hydrogenation so that its presence during the hydrogenation step is assured.

The following examples will illustrate the manner in which our invention may be practiced, but it is to be understood that the invention is not to be limited to the specific conditions given therein but rather by the scope of the appended claims.

Example 1.In accordance with prior practices soap was prepared from linseed oil as follows. Raw linseed oil having an iodine value of about 191.7 was alkali refined and filtered. To the thus treated oil in a hydrogenation apparatus was added 1% of a copper-nickel hydrogenation catalyst. The system was then filled with hydrogen and the oil was heated during vigorous agitation to 165 C. Agitation and in troduction of hydrogen at this temperature was continued until the Butyro refractive index at 48 C. was 49.5. The iodine value of the hydrogenated oil was about 83.8. The oil-catalyst mixture was then cooled to 60 C., filtered through guhr and then bleached with the aid of 2% bleaching earth for minutes at 60 C. The hydrogenated and bleached oil on saponification with caustic soda yielded a soap possessing a distinctly pink color. In handling very large batches of materials as in the commercial production of soap, oxidation of the contained gamma tocopherol during the soap making process may not be sufficient due to limited contact with the air to cause an immediate notice= able pink coloration. However, the pink coloration will gradually become more evident and will fully develop in the final product on subsequent exposure to the air.

Another sample of the same refined and filtered linseed oil was hydrogenated under the same conditions in the presence of 0.1% of substantially anhydrous hydrogen peroxide, the Butyro refractive index at 48 C. at the end of the hydrogenation step being 49.0 (iodine value=80.'7). After the oil had been bleached with bleaching earth under the same conditions as indicated in the preceding paragraph, it was saponified with caustic soda. The resulting soap on prolonged exposure to air did not develop the characteristic pink coloration possessed by the soap prepared from the linseed oil hydrogenated in the absence of the hydrogen pero'. Example 2.--A quantity of refined and filtered linseed oil having an iodine value of about 190.8 was hydrogenated and bleached as in Example 1, but in the presence of 0.05% of trans-Q-decalylhydroperoxide (ClOHl'IOOI-D to a Butyro reiractive index at 48 C. of 49.0. The iodine value of the hydrogenated oil was about 80.7. Soap prepared -from the thus treated linseed oil was substantially white in contrast to the pink soap which resulted on saponification of linseed oil hydrogenated in the absence of a hydroperoxide. Example 3.--Refined and filtered soybean oil having an iodine value of about 140.0 was hydrogenated substantially in accordance with the conditions of Example 1, to a Butyro refractive index at 48 C. of 48.5 (iodine va1ue=5'7.5) in the absence of a hydroperoxide. Soap prepared from the hydrogenated oil was pink in color.

Another portion of the same refined and filtered soybean oil was hydrogenated under similar conditions in the presence of 0.2% tertiary g butyl hydroperoxide to a Butyro refractive index of 47.9 at 48 C. (iodine value- 52.0). Soap prepared from this hydrogenated oil did not develop a pink color on exposure to air.

Example 4.-Another sample of soybean oil having an iodine value of about 132.8 was refined and filtered and then hydrogenated to a Butyro refractive index at 48 C. of 47.2 (iodine value=47.5) without the use of hydroperoxide. Soap prepared from the hydrogenated oil was distinctly pink in color.

When a portion of the same refined and filtered soybean oil was hydrogenated in the presence of 0.2% of a liquid, colorless, saturated tertiary alkyl hydroperoxide having an average of '7 carbon atoms and believed to be of the type covered in U. 5. Patent 2,403,722 to a Butyro refractive index at 48 C. of 47.3 (iodine value=48.0), a hydrogenated product was obtained which, on saponification, yielded a soap which did not develop the characteristic coloration.

Example 5.A sample of refined and filtered linseed oil was hydrogenated in the absence of hydroperoxide to a Butyro refractive index at 48 C. of 48.8. The hydrogenated oil, having an iodine value of about 79.7, was then saponified to yield a soap possessing the characteristic pink color.

A portion of the same raw linseed oil was stored for many months at room temperature until it developed a peroxide value of 0.9. This oil Was then refined, filtered, and hydrogenated to an iodine value of about 80.0 under conditions comparable with those given in the preceding paragraph. The hardened oil produced on saponification a soap which did not develop the characteristic pink color on exposure to air.

Example 6.-A refined and filtered linseed oil (iodine value=189.6) which after customary hydrogenation gave a soap with a pink coloration was hydrogenated under the conditions of Example 1 in the presence of' 0.2% of highly concentrated hydroperoxide derived from the methyl ester of the fatty acids of oliveoil and having a peroxide value of 2690. This hydroperoxide was prepared in accordance with directions given in the literature by air blowing olive oil methyl ester at temperatures somewhat below 35 C. The hydrogenated linseed oil resulting from the treatment had an iodine value of about 85.1 and yielded a substantially white soap which did not develop the characteristic pink coloration.

In addition to the above-examples, We have also successfully practiced the invention with ethyl hydroperoxide and triphenyl methyl hydroperoxide. As indicated previously, compounds such as'methyl hydroperoxide may also be used, in which case however it should be borne in mind that such compounds are more volatile than the higher molecular weight derivatives, and provisions should be made connection with their use for avoiding loss-due to volatilization. Moreover the use of methyl peroxide is dangerous in view of its explosive nature.

Other hydroperoxides which may be employed include:

Cyclohexene hydroperoxide 7-para-Cymyl' hydroperoxide Hydrindene hydroperoxide l-hydroxycyclooctyl hydroperoxide l-hydroxydodecyl hydroperoxide 3-para-Menthenyl hydroperoxide para-Methylbenzyl hydroperoxide Monoperphthalic acid Octahydroanthracene hydroperoxide Propyl hydroperoxide Tetrahydronaphthyl hydroperoxide Generally speaking, other organic hydroperoxides of the formula R-O-O-H in which R represents an aliphatic, aromatic, hydroaromatic, aliphatic-aromatic or aliphatic-hydroaromatic group may be employed without departing from the spirit of the invention and it is to be noted that the groups represented by R may be substituted groups.

It has been shown that natural fat hydroperoxides may be employed in the practice of the invention and these compounds may be produced and applied in various ways. For example, the gamma-tocopherol-containing vegetable oil in the crude or refined state may be exposed to air below room temperature thus inducing oxidation to produce fat hydroperoxides in the oil. The oil also may be stirred with air at room temperature or at slightly elevated temperatures such as 35 C. until a suitable content of fat hydroperoxide is reached. In this connection our investigations have shown that oxidation of the oils to a peroxide value from about 0.6 to about 1 yields an oil containing the required amount of fat hydroperoxide to inactivate the gamma tocopherol.

Fat hydroperoxides for use as products to add to the vegetable oils which are to be hydrogenated for ultimate conversion into soap may be pre-- pared by the treatment of a highly unsaturated oil, suc has olive oil, corn oil, linseed oil, cottonseed oil, castor oil, menhaden oil, and other oils having iodine values above 75, with air or oxygen for an extended period, thereby developing a product which consists essentially of fat hydroperoxides and which may be added to the vegetable oil before hydrogenation as in the case of other hydroperoxides in quantities more fully hereinafter set forth. The hydroperoxide requirements for each gamma-tocopherol-containing vegetable oil vary with the oil and also with the hydroperoxide employed. Thus it will be understood that for each oil and each hydroperoxide optimum conditions of hydroperoxide concentration exist. If the quantity of hydroperoxide is below minimum requirements, the inactivation of gamma tocopherol will be insufficient and the soap prepared from the hydrogenated material will possess more or less coloration due to the red orthoquinone compounds resulting from the oxidation of the inactivated gamma tocopherol. If the optimum requirements are exceeded, undesirable color formation in oil and resulting soap may take place. Thus when tertiary butyl hydroperoxide is employed, about 0.05 per cent is required for the treatment of average linseed oil and 0.2 per cent for the treatment of average soybean oil. The quantity of hydroperoxide required also depends upon the nature of the vegetable oil and the minor constituents present in the oil, and especially upon the tocopherol. As a generalization it may be stated that an amount of hydroperoxide sufiicient to inactivate the gamma tocopherol should be employed, but that this amount should not be substantially in excess of 0.5 per cent based on the weight of the oil.

The specific examples given above show the practice of the invention on linseed oil and soybean oil. The invention is not limited thereto, however, since any other vegetable oil containing gamma tocopherol, such as cottonseed, sunflower seed, corn, peanut, olive and the like may be rendered more valuable for use as a soap making stock by the use of the present invention in the processing thereof.

Although the conditions of hydrogenation used in the process of the above specific examples are the practical conditions employed to a large extent in industry and therefore are preferred, the invention is not so limited in this regard. Hydrogenation of the vegetable oil under other practical conditions with the use of metallic catalysts other than the copper-nickel catalyst of the examples and in the presence of the hydroperoxide will eifectively inactivate the gamma tocopherol and inhibit the formation of the objectionable coloration in the soap ultimately produced from the oil. Thus metallic catalysts such as nickel in its various forms, nickel-vanadium, nickelchromium, palladium, and the like may be employed.

The temperature at which the vegetable oil is treated in accordance with our process also may be varied over a wide range. Thus by increasing the catalyst usage, by employing one of the more active catalysts, or by conducting the hydrogenation under pressure, the temperature of treatment may be reduced from that shown in the examples to -100 C. More elevated temperatures such as 200 C.-225 C. may prove advantageous in the treatment of some vegetable oils and may be employed.

Thus it will be noted that the beneficial results of the invention may be obtained by hydrogenating the gamma-tocopherol-containing vegetable oil in the presence of the hydroperoxide under any practical conditions efiecting absorption of hydrogen by the oil to reduce the iodine value of the oil (the degree of unsaturation) and in the claims reference to the step of catalytically hydrogenating is to be so construed.

The chemical mechanism involved in the inactivation of the gamma tocopherol with respect to the coloration of soaps made therefrom has concentration of gamma not yet been completely determined. However, our observations do show that in the practice of the invention the loss of the total tocopherol according to conventional methods of determination is relatively small and the loss of gamma tocopherol is insufficient to account for the suppression of the coloration. Accordingly the soap products resulting from the practice of the invention'are unique in that they are substantially free of red orthoquinone compounds and contain gamma tocopherol which is inhibited against oxidation to such red orthoquinone derivatives.

Having thus described the invention, what we claim and desire to secure by Letters Patent is:

1. In the process of preparing gammatocopherol-containing vegetable oils for soap manufacture, the step of catalytically hydrogenating said oil in the presence of a hydroperoxide of the formula R-O'OH wherein R. is

selected from the group consisting of hydrogen F and an organic radical, the amount of hydroperoxide being suflicient to inhibit the oxidation of gamma tocopherol in soap made therefrom when exposed to air, but not substantially exceeding 0.5 per cent based on the weight of the oil.

2. The process of claim 1, in which the hydroperoxide is hydrogen peroxide of not less than 90 per cent concentration.

3. The process of claim 1, in which the hydroperoxide is tertiary butyl hydroperoxide.

4. The process of claim 1, in which the hydroperoxide is a fat hydroperoxide.

5. The process of preparing soap from a vegetable oil containing gamma tocopherol which comprises treating the vegetable oil with hydrogen gas in the presence of a metallic hydrogenating catalyst and a hydroperoxide of the formula R 0-O-H wherein R is selected from the group consisting of hydrogen and an organic radical,

under conditions which produce a reduction of the iodine value of the oil, and saponifying the hydrogenated oil, the amount of hydroperoxide present during hydrogenation being suflicient to inhibit the formation of gamma tocopherol orthoquinone but not substantially more than 0.5 per cent based on the weight of the oil.

6. The process of claim 5, in which the temperature of hydrogenation is above 90 C.

7. The process of claim 5, in which the vegetable oil is linseed oil.

8. The process of claim 5, in which the vegetable oil is soybean oil.

9. The process of claim 5, in which the vegetable oil is cottonseed oil.

10. The process of preparing a vegetable oil containing gamma tocopherol for soap manufacture, comprising oxidizing the oil with elemental oxygen until it has a peroxide value from about 0.6 to about 1 and then subjecting the oil to hydrogenation in the presence of a metallic hydrogenation catalyst under conditions which produce a reduction of the iodine value of the oil.

11. A soap product prepared in accordance with the process of claim 5.

WILLY LANGE. ROBERT G. FOLZENLOGEN.

REFERENCES CITED The following referenlces are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,476,330 Ellis Dec. 4, 1923 1,813,512 Rutzler July '7, 1931 2,197,269 Guillaudeu Apr. 16, 1940 2,300,416 Grondal et al Nov. 3, 1942 2,353,229 Durkee July 11, 1944 2,428,367 Henderson Oct. 7, 194'! OTHER. REFERENCES Davidsohn, Soap, Perf. 8a Cosmetics, Sept. 1938, page 796.