US2371307A - Purification of organic compounds - Google Patents

Description

the resulting product.

Patented Mar. 13, 1945 Fries PURIFICATION OF ORGANIC COMPOUNDS Joseph Edward Mitchell, Jersey City, N. 3., assignor'to Colgate-Palmolive-Peet Company, Jersey City, N. J a corporation of Delaware No Drawing. Application December 2, 1939,

' Serial No. 307,256

19 Claims.

This invention relates to the treatment of fatty acid compositions containing considerable contaminating substances, to produce valuable, light-colored, organic materials, detergents, and like agents, and, in particular, it relates to the treatment of crude products containing fatty acids obtained as by-products in the processing of wood and the like for the production of paper. The invention includes not only a process of producing the improved materials, but also the improved products and detergents thereby obtained.

Numerous methods have been devised for removing color, odor or other impurities from fatty acids, fatty oils and fats, but in many of these processes the fatty material is changed in its physical properties by the treatment. Chemical change, saturation, and/or polymerization often occur in the prior art processes of purification. By the presentinvention, it is now possible to remove dark, malodorous and/or unstable impurities without substantially modifying the fatty material being treated.

In producing wood pulp by an alkaline process, for example the sulphate process, the cellulose portions of the wood are obtained by digesting the wood with a solution of sodium' hydroxide, sodium sulphide and sodium sulphate, with separation from the cellulosic portion of various organic products, including fatty acid soaps, ligneous material, soaps of resin-like material, phytosterols, phenolic bodies, oxygengated and sulphur-containing bodies, tar, pitch, the treating chemicals and the water. This mixture of products, commonly termed black liquor, is subsequently treated to recover the soda which it contains by evaporating the water and roasting there separates from the black liquor the crude floating soap referred to above, which mainly consists of the sodium salts of fatty acids and sodium salts of resin acids, together with a considerable proportion of unsaponifiable material. The crude floating soap is dark in color and has an extremely objectionable odor. It may be treated wtih dilute solutions of acids and/or acid gases, such as sulphuric acid, hydrochloric acid, and sulphur dioxide, to liberate the fatty acids and the other acids, which mixed product is commonly known as tall oil. This product has an undesirable color and odor, and contains roughly about 90% of a mixture of fatty acids and some resin acids, and about of unsaponifiable material, including hydroxylated material, hydrocarbon material, etc, The com- During such recovery position of the various constituents is very complex, and the exact chemical structure thereof is not known. The proportions of the various constituents may vary more or less widely, depending upon the source, the particular method of treatment of the wood to produce the paper pulp, etc.

The present invention is directed to a process for the production of relatively pure, uniform, organic materials, including commercially valuable soaps, from tall oil or its soaps, either in the form of crude floating soap, crude tall oil, distilled tall oil, or fractionated tall oil, or purified by various methods, including solvent extraction, alkali brine extraction, and/or high temperature steam treatment of the anhydrous soap thereof. It has now been made possible by the present invention to prepare relatively pureproducts from tall oil, which materials may be used for various purposes in the form of individual constituents or admixtures thereof. The fatty acids, with or without additional treatments, are-preferably converted to soaps with or without the other acids and materials present in the original mixture.

In accordance with the present invention the tall oil or other fatty acid material, with or without pretreatment, is treated with a halide of an amphoteric metal, preferably anhydrous stannic chloride, thereby precipitating the dark-colored constituents in the tall oil and leaving a lightcolored material suitable for the preparation of fatty acid soaps. The tall oil is preferably dissolved in a solvent, particularly a hydrocarbon solvent, of which the preferred type is a gasoline or other saturated aliphatic hydrocarbon. When talloil is dissolved in gasoline, a brown fibrous precipitate is often formed, which precipitate appears to be ligneous material. This precipitate may or may not be separated by decanting, centrifuging, and/or filtering. The amphoteric metal halides likewise may be dissolved in the same or a different solvent before addition to the tall oil or solution thereof, but this, although sometimes desirable, is not essential. It is possible to dissolve the amphoteric metal halide in a solvent which itself has the property of extracting certain substances from a gasoline solution of tall oil. For example, the gasoline solution of tall oil may be admixed with a liquid sulphur dioxide solution of an amphoteric metal halide, at a temperature at which liquid sulphur dioxide and a gasoline solution are miscible, and the mixture then cooled to form immiscible layers of the two solvents. The gasoline layer of the preferred product may then be decanted from the dark-colored residue in liquid sulphur dioxide.

It is another feature of this invention to react the fatty acid material or its soap with nascent hydrogen to a limited extent, to alter the more reactive, less soluble, colored or potentially colored and/or gum-forming bodies in the oil. Tall oil may be treated with the hydrogen generated in situ by the reaction between an acid and a metal, such as sulphuric acid and zinc, or an alkali and a metal, such as caustic soda and aluminum.

One variation of the invention involves the use of a metal and a hydrohallde, which materials not only generate nascent hydrogen, but also produce amphoteric metal halides which exert the additional purifying action described hereinbefore. For example, zinc and hydrochloric acid will yield nascent hydrogen and zinc chloride, both of which aid in the purification of the tall oil under treatment.

Although it is not essential in treating the tall oil with theacid-reacting metal halides and/or with th nascent hydrogen, it is preferred so to treat the tall oil while dissolved in a solvent such as gasoline. It is within the scope of this invention to separate the gasoline-insoluble resinous matter, before and/or after these treatments, by

decantation, centrifugation, and/or filtration.

The gasoline solution also may be extracted by furfural, liquid sulphur dioxide, or other organic or inorganic solvents. V

In preparing purer products it is .also possible to pretreat the tall oil soaps, thinned with water,

with a current of steam and/or other gases, and then to contact this material with an alkaline sodium chloride brine. vIt is advantageous to treat the thinned soap with the steam or other gases in an alkaline condition and/or in the presence of added inorganic salts. Discoloration of the fatty acids is prevented by having them in the form of alkaline soaps, and the inorganic tional distillation of the acids obtained from the tall oil soaps preferably from. soaps, which have been treated to remove the non-saponifiable materials. The fractionation may be before or after the treatment with the amphoteric metal halide. The distillation may be conducted with or without additional materials such as aliphatic, alicyclic, terpene and aromatic hydrocarbons, fatty acids,

' and mixtures thereof.

bases and salts serve to open the soap in order to facilitate passing the steam and other gases therethrough. The blowing may be combined with a graining operation by treating the tall oil soaps with an alkaline brine, meanwhile stirring well with a current of steam or the like. The operation may be conducted at any time, but is preferably conducted shortly after the crude soap is removed from the black liquor. The soap is salted out of the mixture by this treatment, and sodium phenates and lignin-like materials pass into the brine solution.

) The unsaponifiable materials are preferably removed from the tall oil by the treatment of the tall oil. with or without other pretreatments, after or during saponification, at relatively high temperatures, at least above the melting point of the anhydrous soap thereof, while passing a strong current of steam or inert gas through it, advantageously under reduced pressure, in the substantial absence of air and liquid water. The

tall oil may be purified by this or any of the other procedures described in detail in the Dreger U. S. Patent No. 2,240,365, granted April 29, 1941, before, during or after the novel treatments of this invention. The product, thus freed from unsaponifiable material, is also free from objectionable odor and forms a harder soap when grained, and the acids which may be liberated from it have a considerably lower iodine number and higher viscosity, indicating a change in the constitution thereof. The unsaponiflable material may be re- The invention will be further illustrated by the following specific examples, although it is not limited thereto.

Example I 150 parts of crude tall oil are dissolved in 600 parts of light petroleumether. 1.5 parts of anhydrous stannic chloride in 20 parts by volume of light petroleum ether are added to the solution. The solution turns dark in color and a dark precipitate forms. This precipitate is filtered from the supernatant solution and the clear solution is washed with water. The petroleum ether solution is then dried and the solvent evaporated. The yield of purified tall oil is about 96%.

Example III.

100 parts by weight of crude tall oil acids from which the gasoline insolubles have been separated are dissolved in 500 volumes of petroleum ether. 0.5 part by weight of anhydrous stannic chloride is dissolved in 20 volumes of petroleum ether. The solution of acids is then mixed with the stannic chloride solution. A dark precipitate forms'and is filtered out of the solution. The filtrate is washed with water and dried over sodium sulphate. The solvent is distilled off and a yield of about of purified oil is obtained.

Example IV parts by weight of tall oil acids (obtained by acldulation of crude tall oil soap which has been brine washed) dissolved in 500 volumes of petroleum ether are treated with 1 part by weight of anhydrous stannic chloride. The procedure of Example I is repeated. The yield of improved tall oil acids is 90%.

Example V 100 parts by weight of crude tall oil are dissolved in 300 volumes of petroleum ether. To this solution 5 parts of stannic chloride are added and the mixture is refluxed on the steam bath at about 60 C. for one hour. A dark precipitate Example VI 50 parts by weight of crude tall oil are treated with 2.5 parts by weight of zinc dust and 100 parts by weight of water and heated to 80 C. 50 volumes of concentrated hydrochloric acid are added in small increments during a thirty minute period with agitating. After no more evolution of gas occurs, the material is cooled and extracted with petroleum ether. The solvent-oil solution is washed with water and dried over Na2SO4. An improved tall oil amounting to 96% of starting material is obtained.

Example VII 50 parts by weight of crude tall oil are mixed with 2.5 parts by weight of zinc dust and then about 100 parts by volume of concentrated hy-- drochloric acid are added, with mixing, in small increments over a period of about thirty minutes. The mixture is then cooled and extracted with petroleum ether. The solution is dried with sodium sulphate and the solvent removed. The yield of purified tall oil is about 98% and the product is better than that obtained according to the process of Example VI.

Example VIII 200 parts by weight of dark-colored oleic acid (red oil) dissolved in. 600 parts by volume of a pentane-hexane fraction of petroleum are thoroughly admixed at room temperature with a solu time of 1 part by weight of stannic chloride in 100 parts by volume of the same solvent. A darlz precipitate forms which is filtered ofi. The hydrocarbon solution of treated oleic acid is washed with water and the purified oil recovered by evaporation of the solvent. A yield of 98% of light colored material possessing a pleasant odor is ob tained. The physical properties of the product correspond to those of oleic acid, thus demonstrating that this treatment, even of unsaturated fatty acids, does not cause any noticeable chemical change of the fatty material.

Stannic chloride is preferred, but it is also within the scope of this invention to use, alone or in admixture, other amphoteric metal halides such as zinc chloride, aluminum chloride, aluminum bromide, starmous chloride, stannic bromide, titanium tetrachloride, zinc bromide, and antimony chloride, and even the more reactive metal halides such as boron fluoride and boron chloride. Other halides, particularly those of the monovalent elements or groups, including the hydrohalides, ammonium halides, and alkali metal halides, may be used in combination with the amphoteric metal halides. These may be used as mixtures of the individuals or in complexes. For example, it is also possible to use the complex salts of these compounds, such as stannic ammonium chloride, chlorostannic acid, plumbic ammonium chloride, sodium borofluoride, or salts mixed with sodium chloride, potassium chloride or other halides. These halides function most effectively in the anhydrous state, but those which are stable in contact with water may be employed in the presence thereof. The quantity of metal halide used depends on the matemetal halide will aid in the purification, it is preferred to use between 0.1% and 1.0% for effective economical operation. The proportion of amphoteric metal halide may be higher, but in excess of 5%-the improved results do not ordinarily merit the increased cost. The time of treatment may be varied from a few minutes contact to several hours, but only a short period is usually required.

For economy of operation and because of its selective solvent action, it is preferred touse gasoline or the corresponding saturated aliphatic hydrocarbons such as hexane, heptane, octane and higher homologues. It is also within the scope of this invention, however, to employ other solvents for tall oil and/or the metal halides.

Among such solvents are carbon tetra-chloride,

ethyl ether, ethylene dichloride, chloroform, ethyl acetate, isopropyl ether, liquid sulphur dioxide, naphtha, kerosene, turpentine, propane, butane, pentane, hexane, octane, benzene, toluene, xylene, ethyl benzene, olefines, dichlordifluormethane, dichlordiethylether, trichlorethylene, and the like, or various mixtures thereof.

When employing the normal gaseous solvents it is, of course, necessary to operate at low temperatures and/or increased pressures. The temperature of operation may be varied over a wide range and depends to a large extent on the relative reactivity of the amphoteric metal halide employed and the character and viscosity of the mixture under treatment. It is advantageous to operate at moderate temperatures in order to obtain good separation without substantial modification of the fatty acid material. The preferred temperature range with unsaturated fatty acids isbetween about 0 and 40 C., but much higher temperatures may be employed with the saturated fatty acids.

The treatment may be continuously operated by continuously dissolving tall oil in a solvent, continuously adding a solution of the amphoteric metal halide to the tall oil solution, continuously filtering the tall oil solution with or without the aid of silica gel, filter clay or the like, continuous,- ly counter-currently washing the tall oil solution with water or aqueous salt solution such as ammonium chloride brine to remove residual amphoteric metal'halide therein, continuously heating the tall oil solution to an elevated temperature, continuously flashing the tall oil solution to remove the solvent, and continuously blowing the tall oil free of solvent with steam in a suitable column. The stannic chloride or other amphoteric metal halides may be recovered from the separated precipitate and re-used. The filter aid may be recovered by solvent extraction of the organic material and/or by burning of the residual organic matter therein.

It is within the scope of this invention to treat other fatty acid materials according to any of the procedures described hereinbefore for treating tall oil. Suitable organic acid materials which maybe so treated alone or along with tall oil are wool fat, certain grades of garbage grease, whale oil and fish oils including salmon oil, menhaden oil, cod liver oil, and shark oil, spermaceti, tallow, coconut oil, olive oil, cottonseed oil/cottonseed oil foots, linseed oil, China-wood oil, soya bean oil, palm oil, palm nut oil, mont'an wax, carnauba wax, Japan wax, Chinese wax, tung oil, rape seed oil, peanut oil, sunflower oil, babassu nut oil, corn oil, sesame oil, cocoa. butter, cashew nut oil, cashew nut shell oil, oxidized petroleum, naphthenic acids, the individual saturated and unsaturated fatty acids thereof, or mixtures of any of the above listed waxes, fatty acids, fats, fatty oils, and/or other esters thereof.

It is possible to use either the amphoteric metal halide treatment or the nascent hydrogenation treatment alone, in combination, or simultaneously as indicated above. These treatments may be in any order and may be conducted in combination with one or more of the other purification procedures herein disclosed. Although it is not essential, these novel treatments are preferably conducted after all other purification methods have been performed but prior to the formation of a finished soap. If any solvent type of tetraphosphoric, pyrophosphoric or hexa-' metaphosphoric acid and their alkali metal, ammonia, and certain amine salts or alkyl esters; methyl and ethyl cellulose; coloring matter, such as dyes, lakes, and pigments; abrasives and fillers, such as silica, pumice, feldspar, precipitated chalk, infusorial earth, bentonite, talc, starch, and air; liquids, including carbon tetrachloride, perchlorethylene, trichlorethylene, glycerine, ethyl alcohol, glycol, tetrahydrofurfuryl alcohol, phenol,

cyclohexanol, water, tetralin, decalin, pine oil, mineral oil, mineral oil extracts, and naphtha; perfumes and deodorants; fats, oils, fatty acids, monoglycerides, waxes, gums, glue and resins; germicides, such as phenol and organic or inorganic mercury compounds; any of the common, water-soluble alkali metal or ammonium salts, and various mixtures thereof. The type of addit on a ent to be used will depend, of course, on the ultimate use of the new soap composition. The various ingredients may be mixed with the soap by any of the common methods, such as milling, stirring, kneading, crutching, fusing, and drying of mixed solutions or dispersions.

1. A process which comprises treating tall oil in a liquid state with stannic chloride at a temperature not greater than 40 C. in order to improve the fatty acids in the tall 011.

2. A, process which comprises treating a liquid solution of tall oil with stannic chloride at a temperature not greater than 40 C., separating the insoluble material from the tall oil solution, hydrolyzing the remaining stannic chloride, removing the solvent and treating with steam.

3. A process which comprises treating a liquid solution of tall oil with stannic chloride and hydrochloric acid at a temperature not greater than 40 C., and separating the insoluble material from the improved tall oil.

4. A process which comprises treating a liquid solution of tall oil with chlorostannic acid at a temperature not greater than 40 C. and sep- Where, in this specification and the appended claims, reference is made to tall oil, it is understood that it refers to that product which is obtained as a by-product from the processing of wood to produce paper pulp, which product consists of a mixture of fatty acids and other organic acids, unsaponifiable material and impurities, whether produced by the sulphate, sulphite, soda or other processes, and whether distilled or not;

and where reference is made to saponified tall oil,

it is understood that it is to such a product in saponified form, whether obtained by saponlfying tall oil, or in the crude form which is directly separated from the liquors of the paper-making process without acidification to produce the tall oil.

As many widely different embodiments of the invention may be made without departing from arating the insoluble material from the improved tall oil.

5. A process which comprises extracting a tall oil soap with an alkali brine solution, acidifying the tall oil soap, dissolving the tall oil acids in benzine, treating the liquid benzine solution with stannic chloride at a temperature not greater than 40 C., separating the benzine solution from the material insoluble therein, removing excess stannic chloride from the benzine solution of tall oil, removing the solvent from the oil, and treating the oil with steam thereby removing residual solvent and improving the odor.

6. A process of improving impure fatty acid material which comprises treating under acidic conditions a water-insoluble long-chain fatty acid material of the class consisting of fatty acids and esters thereof in a liquid state with stannic chloride at a temperature up to about 60 C. but below the temperature of substantial modification of the fatty acid material.

'7. A process of improving impure fatty acid material which comprises treating under acidic conditions a solution of a water-insoluble longchain fatty acid material of the class consisting of fatty acids and esters thereof with stannic chloride at a temperature up to about 60 C. but below the temperature of substantial modification of the fatty acid material, and separating the insoluble material from the solution of improved fatty acid material.

8. A process of improving impure fatty acid material which comprises treating under acidic conditions-a hydrocarbon solution of a waterinsoluble long-chain fatty acid material of the class consisting of fatty acids and esters thereof with stannic chloride at a temperature of about 60 C., and separatingthe insoluble material from the hydrocarbon solution of improved fatty acid material.

9. A process of improving impure fatty acid material which comprises treating under acidic conditions a solution of one part of water-im soluble long-chain fatty acid material of the class consisting of fatty acids and esters thereof in at least threeparts of petroleum hydrocarbon solvent with stannic chloride at a temperature up to about 60 C. but below the temperature of substantial modification of the fatty acid material, and separating the insoluble material from the hydrocarbon solution of improved fatty acid material.

10. A process of improving impure fatty acid material which comprises treating under acidic conditions a water-insoluble long-chain fatty acid material of the class consisting of fatty acids and esters thereof in a liquid state with stannic chloride at a temperature not greater than 40 C.

11. A process of improving impure fatty acids which comprises treating under acidic conditions a water-insoluble long-chain fatty acid in a liquid state with stannic chloride at a temperature up to about 60 C. but below the temperature of substantial modification of the fatty acid.

12. A process of improving impure fatty acids which comprises treating under acidic conditions a petroleum hydrocarbon solution of a waterinsoluble long-chain fatty acid with stannic chloride at a temperature up to about 60 C. but

below the temperature of substantial modifica-' tion of the fatty acid, and separating the insoluble material from the solution of improved fatty acid.

13. A process of improving impure fatty acids which comprises treating under acidic conditions a water-insoluble long-chain fatty acid in a liquid state with stannic chloride at a temperature not greater than 40 C.

14. A process of improving impure fatty acids which comprises treating under acidic conditions a solution of a water-insoluble long-chain fatty acid with stannic chloride at a temperature not greater than 40 C., and separating the insoluble material from the solution of improved fatty acid.

15. A process of improving impure fatty acids which comprises treating under acidic conditions a water-insoluble long-chain fatty acid in a liquid state with stannic chloride and a halide of a non-amphoteric element at a temperature not reater than C., and separating the insoluble material from the improved fatty acid.

16. A process of improving impure tall oil which comprises treating tall oil in a liquid state with stannic chloride at a, temperature up to about 17. A process of improving impure tall oil which comprises treating a hydrocarbon solution of tall oil with stannic chloride at a temperature material which comprises treating under acidic conditions a water-insoluble long-chain fatty acid material of the class consisting of fatty acids and esters thereof in a liquid state with a member of the group consisting of stannic chloride and chlorostannic acid at a temperature up to about 60 C. but below the temperature of substantial modification of the fatty acid material.

JOSEPH EDWARD MI'ICHELL.