US3526647A - Process for producing wool wax alcohols and fatty acids - Google Patents

Description

United States Patent 3,526,647 PROCESS FOR PRODUCING WOOL WAX ALCOHOLS AND FATTY ACIDS Conrad J. Sunde, Garden City, N.Y., and Thomas B. Richey, Jr., Westfield, N.J., assignors to Malmstrom Chemical Corp., Linden, N.J., a corporation of New Jersey No Drawing. Filed July 10, 1968, Ser. No. 743,625 Int. Cl. C07c 167/42 US. Cl. 260-39725 6 Claims ABSTRACT OF THE DISCLOSURE Wool wax alcohols and fatty acids are produced by saponifying wool grease with caustic alkali in a co-solvent mixture of isopropyl alcohol and water, followed by extraction of the wool wax alcohols from the saponified grease by subjecting the saponified product to countercurrent extraction with heptane. The heptane extract is washed, first with dilute KOH solution, and then with Water, using a counter-current rotary disc flow extractor. The solvent is then evaporated from the purified extract to recover the wool wax alcohols. The raflinate, which contains soaps of fatty acids, alcohol and some heptane, is

. acidified and then stripped free of the solvent fraction in a continuous stripper still to recover the fatty acid, the latter being then water-washed and dried.

This invention relates to the production of wool wax alcohol and wool wax fatty acids, and is more particularly concerned with the production of these materials from wool grease.

It has heretofore been suggested to produce these alcohols and acids from wool grease by saponifying the wool grease, then extracting the saponified mass with a solvent for the unsaponifiable constituents, withdrawing the solvent layer and evaporating the solvent from the extract in order to recover the unsaponifiable material.

The procedures heretofore suggested for producing Wool Wax alcohols by saponification of Wool grease, followed by extraction of the saponified mixture, must be carried out under carefully controlled conditions, in order to avoid undesirable phase distribution and the formation of undesirable emulsions. For these and other reasons, complete or substantially complete saponification of wool grease is difficult to achieve.

The principal object of the invention is to provide a process for treating wool grease so as to separate wool wax alcohols and wool wax acids therefrom in a form as pure as possible.

Another object is to provide a process for completely saponifying wool grease whereby to obtain therefrom an alcohol of very low saponification value.

Another object of the invention is to provide a process for the continuous extraction and recovery of wool wax alcohols from saponified wool grease.

Another object of the invention is to provide a process of extracting wool wax alcohols from soaps obtained by the saponification of wool grease.

Another object of the invention is to provide a process for the recovery of wool grease fatty acids from the raifi nate yielded by the extraction of wool wax alcohols from saponified wool grease.

The process of the invention involves, first, the saponifi- "ice cation of the wool grease by means of alkali in the presence of a mixture of isopropyl alcohol and Water as cosolvents; second, the extraction of wool wax alcohol from the saponified mixture, using heptane or hexane as a solvent; and then the Washing of the heptane-wool wax alcohol extract with a solution of potassium hydroxide, and subsequently with water, to wash out the soaps that may be present therein.

It is an advantage of the process that dilution of the saponified product with a certain amount of isopropyl alcohol and water serves to prevent emulsification of the system and permit good separation of phases during the subsequent extraction step.

In accordance with the invention, the extraction step and also, if desired, the washing step are best achieved in a continuous counter-current rotary disc extraction column. The latter may take the form of the well-known Rotating Disc Column or so-called Turbo-Mixer, supplied by the Turbo-Mixer Division of General American T ransportation Corporation, New York, N.Y.

By the procedure of the invention, wool grease can be saponified in a period of less than 24 hours to yield an alcohol fraction having a saponification value of 2.0 or less. The extraction of the wool wax alcohols from the saponified mixture in accordance herewith by the use of heptane as solvent, may be achieved with an extraction efliciency of using a solventzfeed ratio of 1:1. Higher ratios of solvent relative to the feed may be expected to result in even higher extraction efiiciencies as well as in purer products (alcohol and acids).

In carrying out the step of saponifying wool grease, either sodium hydroxide or potassium hydroxide may be employed. We prefer, however, to use sodium hydroxide. The amount of sodium hydroxide should normally approximate 11 to 12% of the wool grease, by weight, charged to the saponifying vessel. The latter is provided with suitable agitation means to facilitate the reaction between the alkali and the fatty acids in the wool grease.

Complete saponification to the extent of at least 99% is essential in order that the wool wax alcohol obtained shall be one having a saponification value of 2 or less. It is an advantage of the invention that it provides a satisfactory method for saponifying wool grease in a manner which yields an alcohol fraction having a saponification value of 2 or less.

We have found that the use of isopropyl alcohol as a co-solvent with water in the step of saponifying the Wool grease facilitates saponification of wool grease and makes it possible to obtain 99% saponification in 24 hours at reflux temperature and atmospheric pressure. The isopropyl alcohol, moreover, also serves as a co-solvent during the subsequent steps of extracting and purifying the wool wax alcohol and wool grease fatty acid fractions.

In the operation of the saponification step, the isopropyl alcohol-water wool grease mixture becomes one phase. Using a reasonable amount of agitation, the saponification of even difficultly saponifiable wool grease may be carried to 95% completion in 6 to 8 hours, and to 99% completion in 24 hours or less, at atmospheric pressure, with production of a wool wax alcohol having a saponification value of 2 or less.

The herein described procedure utilizing isopropyl alcohol as a co-solvent with water in the saponification step makes possible the production of a wool wax alcohol TABLE I Treat Sapon.

mcnt value of Run Solvent Temp. time, Pressure alcohol N0. used batch hrs. used produced 1 50% E20, 40% IPA. 210 8 Atmos. 6. 7 2- 45% E20, 37% IPA. 208 21 Atmos. l. 9 3 40% E10 240 7-8 -20 2. 2 4 235% H2O-.." 245-250 24 15-20 19. 6

As will be noted from Table I, the material obtained in Run #2 (21 hours) exhibited a saponification value of 1.9, and the material obtained in Run #1 (8 hours) exhibited a saponification value of 6.7; whereas those ob tained in Runs #3 and #4, wherein no isopropyl alcohol was mixed with water, exhibited a saponification value of 2.2 in the case of #3, where water and a treatment time of 7-8 hours was used, as compared to a value of 19.6 in Run #4, wherein 235% water and treatment time of 24 hours were used. In both Run #3 and Run #4, pressure equipment is required.

The saponified wool grease is then diluted with a mixture of isopropyl alcohol and water, whereby to prevent emulsification, and permit sharp separation of phases during the subsequent extraction step. To that end, in the case of a saponified mixture made by treating 8000 pounds of lanolin with 910 pounds of sodium hydroxide, 3200 pounds of isopropyl alcohol and 3440 pounds of water, was diluted with approximately 16,000 pounds of isopropyl alcohol and 39,600 pounds of water. It will be seen from the foregoing figures that during saponification, approximately 0.4 part of isopropyl alcohol and approximately 0.43 part of water are used for each part of lanolin, by weight, and for dilution of the saponified product, approximately 2 parts of isopropyl alcohol and approximately 5 parts of water are used (for each part of lanolin, by weight).

The saponified wool grease is then treated to extract the wool wax alcohol therefrom. The extract and extracted soap (ratfinate) are then treated to recover the wool wax alcohol and fatty acid fractions.

In accordance with the invention, the extraction of the wool wax alcohols from the soap-ispropanol-water mixture is carried on continuously and is effected by the use of hexane or heptane as solvent. Hexane, being a volatile, inflammable solvent, it is preferred to employ the less volatile heptane, which has been found to perform equally as well as hexane in the extraction operation.

Preferably, the extracting operation is conducted in the well-known type of rotating disc contactor type of countercurrent extractor columns (referred to herein as the R.D.C. unit). This form of extraction column consists, in brief, of a number of compartments formed by a series of stator rings, with a rotating disc centered in each compartment and supported by a rotating shaft. (Chemical Engineering Progress, vol. 51, No. 3, March 1955, p. 14.)

In the operation of the R.D.C. unit for the extraction of wool wax alcohol from the saponified wool grease mixture, the heptane is introduced at the bottom of the column and functions as the homogeneous or complete phase. It flows upward, therein, counter-currently to the descending saponified mixture, which enters the column at the top. The saponified mixture of soaps, water, and isopropyl alcohol is dispersed by the discs into the form of many small droplets (hence referred to as the discontinuous phase), the size of the droplets depending upon the speed of the rotor, which largely governs the extraction conditions.

The saponified material fed to the R.D.C. unit should be sutficiently diluted with isopropyl alcohol and Water solution to ensure and facilitate separation of the phases in the extraction operation. The concentration of isopropyl alcohol in the mixture of soap, water and isopropyl alcohol which is fed to the extraction column should be high enough to reduce the build-up of solids in the extraction column to a minimum.

In a specific illustration of the extraction step, the solvent (e.g., heptane) was fed to the R.D.C. unit in a ratio of 1:1 relative to the feed of the solution of soaps, water, and isopropyl alcohol thereto, for extracting the wool wax alcohol from the soap, isopropanol, water mixture, This amounts to a ratio of about 5:1 solvent (heptane) relative to wool wax alcohols extracted, in contrast to ratios of the order of :1 in the case of procedures heretofore employed, using batch extraction procedure.

The temperature of both the aqueous feed and of the solvent is maintained at approximately to F. The temperature in the extracting column is maintained at 100 F. or somewhat higher to assist in minimizing the build-up of solids in the column. The rotor speed of the discs may be maintained at 30 to 60 rpm.

The procedure hereinabove described has been found to enable extraction of wool wax alcohols from the saponified wool grease to be effected at extraction efficiencies averaging 95% or better. Extraction efliciency is determined by extracting the extracted raflinate, and measuring the amount of extractable material not extracted by the actual extraction step. Extraction efliciencies obtained by the herein described procedure, calculated from actual runs, vary from a minimum of about 86.4% to as high as 97.7%.

The extract, composed of solvent (heptane) and wool wax alcohol, is discharged at the top of the column of the R.D.C. unit, and is washed, for the removal of soaps, from which fatty acids may be recovered as hereinafter set forth. For the washing of the extract, the latter is delivered to an R.D.C. unit, wherein the washing may be effected by subjecting the extract to counter-current contact first with dilute aqueous solution of potassium hydroxide (desirably a 1% KOH-water solution) followed by washing with water to wash out the KOH.

This Washing of the extract with aqueous alkali may be effected by feeding the KOH water solution to the R.D.C. extracting column at a rate of A to the rate of feed of the extract thereto; the rotor speed being of the order of 50-60 rpm.

The effect of this washing treatment of the extract is indicated by the following data of the ash content of unwashed and washed extract:

Percent ash Unwashed extract 0.81 1400 g. extract washed with 200 ml. 1% KOH (then with 1000 ml. 5050 IPA and water) 0.02

The washing of the extract with water, following the Wash with alkali, has the further function and advantage of removing isopropyl alcohol from the extract. This is The quality of the wool wax alcohols obtained by the practice of the invention is indicated by the data in Table II, showing the results of tests on such wool wax alcohols:

TABLE II Water absorption 1300 M.P. C.) 50-50 Saponification value 6.0 Hydroxyl value 160 Cholesterol (percent) 31.8 Color (30% CCl Absorption on a DU24000 spectrophotometer:

Abs. at 470 .39

Abs. at 520 0.137 Ash (percent) 0.7

The raflinate, i.e., the solution extracted soapawater isopropyl alcohol, that is separated from the wool wax alcohol fraction in the extraction step, is composed mainly of soaps of fatty acids, and some unsaponifiables. It also contains some 4% to heptane and 7-15% isopropyl alcohol. The washes from the alkali and water washing of the heptane extract of the saponified wool grease are desirably combined with the raffinate.

To recover solvent and fatty acids present in the raffinate, the latter is acidified, as with dilute sulphuric acid, to yield the fatty acids of the soaps present in the raffinate. The mixture of fatty acids and solvents is pumped through a continuous stripper column to recover the solvents (heptane and isopropyl alcohol) and completely remove them from the raflinate.

Acidification of the rafiinate should be such as to bring the pH thereof to well below 7.0; otherwise a considerable amount of foaming will occur during the operation of the stripper column for removal of the solvents. The use of a continuous stripper column for recovery of the solvents has the further advantage of contributing to the production of fatty acids of good color, by reason of the low time of contact that prevails during the recovery of the solvents. The stripper column employed may conveniently take the form of the well-known Rodney-Hunt unit.

After removal of the solvents, the fatty acids are decaned, water washed and dried.

The properties of the fatty acids recovered from the rafiinate by the herein described procedure are indicated by the following data:

TABLE III Acid value 149.0 15% Union Colorimeter color 3.4-4 Saponification value 170.5 Hydroxyl value 58.2 Unsaponifiable (percent) 7.4 Iodine value 10.6 Flash point F.) 410 6 1y 180 and an unsaponifiable content of approximately 2.6.

Although the unsaponifiable value of 7.4% in Table III indicates that some wool wax alcohol remained unextracted and was present in the rafiinate, this figure is consistent with the figures above set forth for extraction efficiencies obtainable in the practice of the invention. The use of additional amounts, i.e., a higher ratio, of solvent in the extraction step would serve to reduce substantially the amount of unsaponifiables present in the fatty acid fraction.

What is claimed is:

1. The process of producing wool wax alcohols and acids from wool grease, which comprises saponifying the wool grease in the presence of a co-solvent mixture of isopropyl alcohol and water, and subjecting the saponified wool grease to continuous counter-current extraction in a rotating disc extraction column with a hydrocarbon solvent selected from the group consisting of hexane and heptane, subjecting the solvent extract to continuous coun ter-current washing first with dilute aqueous alkali solution and subsequently with water, and evaporating said solvent from the washed extract to recover the wool Wax alcohols therefrom.

2. The process as defined in claim 1, wherein the solvent from which the wool wax alcohols are recovered is delivered to and utilized as solvent in said extraction step.

3. The process of producing wool wax alcohols which comprises saponifying wool grease in a co-solvent solution of isopropanol and water, treating the saponified mass with a solvent selected from the group consisting of hexane and heptane in counter-current continuous contact in a rotating disc extraction column to extract the wool wax alcohol from said mass, and washing soapy materials from said extract by subjecting the same to continuous countercurrent contact with dilute aqueous solution af alkali.

4. The process as defined in claim 3, wherein fatty acids are recovered from said combined rafiinate and soapy material washed from said extract.

5. The process of producing wool wax alcohols which comprises saponifying wool grease in a co-solvent mixture composed of isopropyl alcohol and water, subjecting the saponified mass to continuous counter-current extraction is a rotating disc extraction column with heptane to separate the wool wax alcohol fraction from the saponified mass, subjecting the extract of the heptane-wool wax alcohol to continuous counter-current washing with dilute alkali solution and with water, and evaporating the heptane from the washed extract fraction to recover the wool Wax alcohol.

6. The process as defined in claim 5, wherein the raffinate obtained in said extraction of said saponified mass with heptane is acidified with mineral acid and subjected to continuous stripping action for removal of solvent and recovery of fatty acids therefrom.

References Cited UNITED STATES PATENTS 2,508,220 5/1950 Buxton 260397.25 2,866,781 12/1958 Chase et al 260-39725 2,905,677 9/1959 Fevig et al. 260-397.25

ELBERT L. ROBERTS, Primary Examiner