US2692886A - Process for improving unsaturated fatty acids or derivatives thereof - Google Patents

Description

Patented Oct. 26, 1954 PROCESS FOR IMPROVING UN SATURATED FATTY ACIDS OR DERIVATIVES THEREOF Johan Jacobus Albert Blekkingh,

Rotterdam,

Netherlands, assignor to Lever Brothers Company, New York, N. Y., a corporation of Maine No Drawing. Application August 22, 1950, Serial No. 180,905

Claims priority, application Netherlands August 31, 1949 8 Claims.

This invention relates to a process for improving unsaturated fatty acids or derivatives thereof.

It is known to improve oils containing unsaturated fatty acid radicals by heating the oils with a nickel or cobalt catalyst which contains nickel or cobalt silicate and a small proportion of sulphur and which has been prepared by the reduction of a nickel or cobalt compound. The heating is carried out at temperatures exceeding 170 C.

In this process double bonds change position and often become conjugated. The occurrence of conjugated double bonds is indicated, among other things, by a higher refractive index and higher specific refraction and by a change in the absorption of ultraviolet light. Simu taneously with the change in position of the double bonds stereoisomers of the cis-trans type form, which is reflected among other things in a change in melting point. The oils treated by this process acquire, however, various undesirable properties. For example, their colour darkens and films obtained from them tend to stay tacky after drying.

It has now been found that unsaturated fatty acids or derivatives thereof can be improved by heating them in the presence of the above mentioned catalysts to a temperature not exceeding 140 C. (preferably between 100 C. and 120 C.) and that the resulting products are substantially free from the above mentioned undesirable properties. Treatment at such lower temperatures prevents the materials from acquiring a dark colour, and films from oils so treated do not stay tacky after drying. Moreover, the percentage of conjugated double bonds can be raised to a figure which is considerably higher than in the case of the known process of heating to temperatures above 170 C.

Thus the present invention provides a process for improving unsaturated fatty acids or derivatives thereof by heating the fatty acid or derivative to a temperature not exceeding 140 C. with a nickel or cobalt catalyst containing nickel or cobalt silicate and a small proportion of sulphur and which has been prepared by the reduction of a nickel or cobalt compound. The preferred temperature is between 100 C. and 120 C.

The process of the invention is particularly useful for the treatment of fatty oils. Such oils may be processed while crude or after a preliminary treatment such as neutralisation and/or bleaching. The fatty oils may be drying or semi-drying oils, and may also be non-drying (Cl. 26(l--405.6)

oils containing oleic acid or other unsaturated fatty acid radicals with a single double bond. Other substances to which the invention can be applied are unsaturated fatty acids such as oleic acid itself and the linseed oil fatty acids, and derivatives of the unsaturated fatty acids, other than the fatty oils, and their esters other than glycerides, for example, the alkyl esters such as the ethyl esters. Mixtures of these substances and materials containing these sub stances, are also suitable for processing according to the invention.

The process is particularly important when applied to oils used in the paint industry, since it enables the production of oils which retain their light colour and which have acquired a high content of conjugated double bonds, as a result of which the oils will polymerise rapidly and dry quickly to waterproof non-tacky films. The specific gravity, viscosity and free fatty acid content of substances treated by the process of the invention remain practically unchanged.

Generally, when the invention is applied to compounds of the type indicated, the double bonds change position. Simultaneously, the cis form of the compound is converted into the trans form. In the case of unsaturated fatty acids or their derivatives with more than one double bond, the most important result of this change of position of the double bonds is the formation of conjugated double bonds. When unsaturated fatty acids or their derivatives with a single double bond, for example, oleic acid or its esters, are treated by the process of the invention, the conversion of the cisinto the trans-form causes a rise in melting point, which is of importance in the manufacture of margarine and other edible fats.

The process of the inventionmay be carried out, with nickel or cobalt catalysts containing a small proportion of sulphur and which have been prepared by the reduction of a precipitate containing nickel or cobalt silicate. These nickel or cobalt catalysts are usually prepared by prepicitating nickel or cobalt in the form of an insoluble compound from a solution of the metal salt, for example nickel or cobalt sulphate, in the presence of a material capable of forming a silicate with a part of the precipitate, for example, diatomaceous earth or water glass. The prepicitate is separated by filtering and washing. Alternatively, the catalyst may be prepared by boiling a precipitate of a com-= pound of the metal, for example, nickel or cobait hydroxide, with a material such as diatomaceous earth or water glass in an alkaline aqueous solutionand separating the precipitate by filtering and washing. The separated precipitate formed by either method is then reduced in a current. of hydrogen at a temperature at which metallic nickel or cobalt is formed, for example 500 C.

The sulphur content can be imparted to the catalyst in various ways at many stages in its preparation, for example by treatingv the precipitate formed with alkali with a solution of a sulphur-containing nickel or cobalt compound such as, for example, nickel sulphate or by mix-- ing the filtered and dried precipitate with sulphur or a sulphur compound. before reduction.

takes place. Alternatively, the sulphur content can be imparted to the catalyst subsequent to its preparation, for example, by treating the reduced catalyst with hydrogen sulphide or by using the reduced catalyst to hydrogenate a sulphur-containing oil. The most suitable proportion of sulphur is between 1 and 10% of the metal by weight.

It is preferred to use a nickel catalyst in carrying out the process of the invention and preferably such a catalyst should contain about 4% of sulphur.

The catalysts used in the process of the invention may contain other conventional ingredients such as carriers.

To obtain rapid improvement, it is advisable to use a fairly large quantity of catalyst, for example between 5 and by weight of catalyst calculated as metal of the weight of the oil to be processed. Contrary to expectation, a higher conjugation may be obtained with suitable oils by the process of the invention than is possible with the same quantity of catalyst in the prior art process carried out at a higher temperature, for example, at 180 C.

When the invention is applied to a substance whose double bonds it is desired to conjugate, it is preferred to continue the treatment until the substance has attained maximum conjugation. This stage can be ascertained from observations on the refractive index of the substance, since this index continues to rise until conjugation attains its maximum.

The time of treatment depends on various factors such as the actual temperature employed, the nature of the catalyst, the desired isomerisation and the like. Usually, the treatment, is continued for from about 2 to 8 hours, although a shorter or longer period of treatment will often produce good results, depending on the circumstances. The best way of determining the most suitable period is to carry out an experimental test in each particular case.

It is advisable to avoid the presence of oxygen as far as possible both in the substances treated and in the catalyst. It is, therefore, preferable to remove oxygen and peroxides from, for example, the oil and to effect isomerisation in vacuo or in an atmosphere of inert gas such a carbon dioxide.

The invention will now be illustrated by the following examples. In these examples the conjugation was found from the rate of adsorption of ultra-violet light of certain wavelengths which are specific for double, triple and multiple conjugated double bonds and the percentage of conjugation was found by addition of the percentages so ascertained. In examples 1 and 2, the

Lovibond Colour index of the product was measured in a one-inch cuvette; in Examples 3 and 5 it was. measured in a one-inchcell- 286 grammes of nickel sulphate (NiSOr'lHzO) was dissolved in water to 600 00s.; 30 grammes of diatomaceous earth was added to this solution and while stirring at boiling temperature 350 grammes sodium carbonate (NazCOa.l0I-I2O) dissolved in water to 720 ccs. was then slowly added over a period of, 1 hours. Boiling for a further short periodof' half-an-hour was followed by filtering and the precipitate was washed with water until no more cloudiness was observed with barium chloride solution. After this the precipitate was boiled with 29 grammes of nickel sulphate (NiSOaTI-IzO) dissolved in water to 1200 ccs. for half an hour while stirring, filtered without washing out and dried. The resulting cake contained 4.5 parts by weight of sulphur per parts by weight of nickel. This cake was reduced in hydrogen at 500 (3., after which the catalyst was ready for use.

A quantity of the catalyst prepared. in this way was added to neutralized and bleached linseed oil, so that nickel to. a quantity of 10% by weight of oil was present. Quantities of this mixture were heated. while stirring in a carbon. dioxide atmosphere to various temperatures for four hours, and the following values were obtained for increase in refractive index, percentage of fatty acid groups with conjugated double bonds and Lovibond colour:

The following results were obtained with a number of other oils including whale oil, all of which were treated as in Example 1:

251 323; fi gfi Percent b fi i 011 33.2 fractive :33;;

I b l. Indax yellow red Soyabean 4 0.7

Example 3 The following increases in melting point were obtained in a similar way with oils having a.

high content of oleic acid.

Examples 1 to 3 show clearly that the best results are obtained at about 100 C. Specific gravity, viscosity and free fatty acid content hardly change at this temperature during isomerization, in contrast to treatment at 180 C.

Example 4 Linseed oil fatty acids are processed in the same way as in Example 1 for 1 hour at 100 C. The increase in refractive index was 0.0120, and the colour was green, in consequence of dissolved nickel. This green colour was removed by sulphuric acid treatment. Linseed oil, treated for 1 hour at 100 C. likewise displayed an increase in refractive index of 0.0120.

Example 5 The methyl esters of linseed oil fatty acids were treated in the same way as in Example 1 for 4 hours at 100 C. Increase in refractive index was 0.0155 and percentage conjugation 55, namely exactly the same as for linseed oil (compare Example 1), Lovibond colour was yellow 40, red 4.

Example 6 Methyloleate was treated in the same way as in Example 1 for 4 hours at various temperatures, after which the free fatty acids were removed by saponification and soap splitting.

Point of Incipient Processing Temperature in 0. Fusion of Colour the Acid in C.

20 none. 32 Do. 37 Do. 39 pale. 42 dark Example 7 Linseed oil was treated in the same way as in Example 1, but with only 4% of catalyst calculated on the basis of nickel to oil for 4 hours at varying temperatures.

Increase in Refractive Index Processing Temperature in C.

I claim:

1. A process for improving a substance selected from the group consisting of unsaturated fatty acids and derivatives thereof, which process comprises heating said substance in :an inert atmosphere to a temperature not exceeding 140 C. with a catalyst selected from the group consisting of cobalt and nickel, and containing a silicate of one of said metals and a small proportion of sulphur said catalyst having been prepared by reduction of a compound of one of said metals.

2. A process for improving a substance selected from a group consisting of unsaturated fatty acids, and derivatives thereof, which process comprises heating said substance in an inert atmosphere to a temperature between C. and C. with a catalyst selected from the group consisting of cobalt and nickel and containing a silicate of one of said metals and a small proportion of sulphur, said catalyst having been prepared by reduction of a compound of one of said metals.

3. A process for improving a substance selected from the group consisting of unsaturated fatty acids and derivatives thereof, which process comprises heating said substance in an inert atmosphere .to a temperature not exceeding C. with a catalyst selected from the group consisting of cobalt and nickel and containing a silicate of one of said metals and a small proportion of sulphur, said catalyst having been prepared by subjecting to a reduction treatment a mixture consisting of said silicate with a compound of one of said metals which compound has been precipitated from an aqueous solution of a soluble salt of one of said metals.

4. A process for improving a substance selected from the group consisting of unsaturated fatty acids and derivatives thereof, which process comprises heating said substance in an inert atmosphere to a temperature not exceeding 140 C. with a nickel catalyst containing nickel silicate and a small proportion of sulphur said catalyst having been prepared by reduction of a nickel compound.

5. A process for improving a fatty oil which comprises heating said oil in an inert atmosphere to a temperature not exceeding 140 C. with an amount calculated as metal between 5 to 10% by weight of the amount of oil of a catalyst selected from the group consisting of cobalt and nickel, and containing a silicate of one of said metals and a small proportion of sulphur, said catalyst having been prepared by reduction of a compound of one of said metals.

6. A process as claimed in claim 4 in which said oil is linseed oil.

7. A process for conjugating a substance selected from the group consisting of unsaturated fatty acids, and derivatives thereof, which process comprises heating said substance in an inert atmosphere to a temperature not exceeding 140 C. and for such a time until maximum conjugation is attained with a catalyst selected from the group consisting of cobalt and nickel, and containing a silicate of one of said metals and a small proportion of sulphur, said catalyst having been prepared by reduction of a compound of one of said metals.

8. A process of improving linseed oil which comprises heating said oil in an inert atmosphere to about 100 C. with an amount calculated as metal by weight of the amount of oil, of a nickel catalyst containing 4.5% by weight of sulphur and which has been prepared by reduction of a 3; Name Date Stejskal' May 15, 1951 Number precipitate containing nickel silicate which nickel silicate has been formed; by heating a suspension of precipitated nickel carbonate in water with diatomaceous earth. OTHER REFERENCES 5 Bailey, Oil and Fat Products, Interscience Pub.

References Cited in the file of this patent 1945 page UNITED STATES PATENTS Name Date Ziels May 3, 1949 1 Number

Claims (1)

1. A PROCESS FOR IMPROVING A SUBSTANCE SELECTED FROM THE GROUP CONSISTING OF UNSATURATED FATTY ACIDS AND DERIVATIVES THEREOF, WHICH PROCESS COMPRISES HEATING SAID SUBSTANCE IN AN INERT ATMOSPHERE TO A TEMPERATURE NOT EXCEEDING 140* C. WITH A CATALYST SELECTED FROM THE GROUP CONSISTING OF COBALT AND NICKEL, AND CONTAINING A SILICATE OF ONE OF SAID METALS AND A SMALL PROPORTION OF SULPHUR SAID CATALYST HAVING BEEN PREPARED BY REDUCTION OF A COMPOUND OF ONE OF SAID MATALS.