US2305498A - Tall oil treatment - Google Patents

Description

. surface of the waste liquor.

Patented j;

National -0il Products Ccinpany,"liarrilon, N L, ncorporation of New Jersey Serial No. 309,103

- No Drawing. Application-Deccan 1 Claims. (o etc-5 911.5) i

phate process. In the sulphate process wood is I digested with an alkaline liquor containing sotit-inst;-

-' an improved and {more eiflc'ient process forseparating tall oil intoits main constituents. A further obiect'of the invention is to provide an improvedprocess for separatingitall,oil-into I itsconstituents and recovering the fatty acids;

in amore saturated form so that the same can be adapted to a wider industrial use;

Other "objects will in part be-obvious'andwill inpart appearhereaften'.

dium sulphate, during which process tall oil-accumulates in the form of its sodium soap on the uents of this oil, after acidification, comprise re-' sinic acids and fatty acids, the latter consisting mainly of oleic, linoleic and linolenic acids, each of which are valuable commodities in substan- The main constittially pure form. Various processes have been proposed inan attempt to effect separation of tall 011 into its main constituents, i. e., fatty acids and resinic acids. One process comprises esterifying the fatty acids in tall oil with a low boiling alcoholand separating the resulting fatty ester from the free rosin acids by distillation or by alkali extraction. Another known process comprises esterifying the fatty acids with'a polyhydric alcohol and distilling off the resinic acids. According to another process, both the fatty acids and the resinic acids are esterifled with a polyhy- 'The foregoing and other objects are accomplished according to the-broader aspects 'ofthe invention whereby tall oil in its acidand/or ester form is'dissolved in a suitable solvent andsubjected to temperatures suillciently low'toeif'ect precipitation of acertain. fraction of or "all of the fatty acids or esters thereof,lfollowed by'removal ofsaid precipitated fraction by'iiltration or centrifuging or byany other known means.

of separating an insoluble solid from a liquid. For the purposes of this invention, .the tall oil esters of the mon'ohydric .aliphaticalcohols 'contaming-from l to 5 carbon atoms are considered,

equivalent to the tall oil-acids, and are, therefore,

to be included in the generic expression tall oil. The resinio acids alone or in admixture with'the more highly unsaturated fatty acids remaining in the solvent may be recovered by distilling oil the solvent. The-tall oil or its esters employed dric alcoholand the resin esters are then catalytically split and the liberated-resinic acids distilled ofi. While theforegoing and other known processes have been employed with varying degrees of success, they all exhibit certain disadvantages, primarily in that only partial separation is effected. Moreover, the fatty acid fraction obtained by these processes, consisting main ly of a mixture of oleic, linoleic and linolenic acids,

is not particularly suitable for a'wide variety of industrial uses. Usually having an iodine value in accordance with the process of the invention may be in, the crude or distilled state and they may be subjected to partial or complete. hydrogenation before being subjected to the chilling and separating steps. If the talloilused in the above mentioned process is of thecrude-or distilled type and has not been subjected to liydrogenation, the filtrate obtained upon separation of the precipitated fatty acids will also contain fatty acids or esters of the more highly unof about 120 or 130, this fatty acid'fraction 0'l" its esters) shows some drying properties, but

these drying properties are not pronounced enough for a drying oil of good quality. On the other hand, this fatty acid fraction\ is too highly un-g saturated to find extensive application in some of the largest fat-consuming industries, namely the soap industry, and in the manufacture of specialties for the textile and tanning trades, the I saturated type, mostly linoleic and linolenic acids. These higher unsaturated fatty acids may then be separated from the rosin by esterification fol- I lowed by alkali extractlon'of the rosin, or by methods disclosed in my co-pending applications,

- Serial NOS. 21"],9'1 -1 and '3Q3,535, filed July 7, l938,

and Ndve'mber9, 1939, respectively. If the tall oil or its esters are hydrogenated 'to-a degree where a at least all the highly unsaturated fatty acids bulk of fats used in these industries being of the l more highly saturated type.

The general object of this invention is to obviate the foregoing and other disadvantages.

A specific object of the invention is to provider-5 have beenconverted t0 oleic acid, the fatty acid fraction can be completely separated from the resinicacids by cooling and iflltrationalone'.

This invention accordingly comprises the severalsteps' andthe relation of one or more of such steps with respect to each of the others thereof, which will be'exemplified in the process I hereinafter disclosed, and the scope of the invention will be indicated in the claims.

In carrying out the process of the invention, the first step involves the dissolving of tall oil in a suitable solvent therefor which is characterized by the property of retaining the resinic acids or derivatives thereof in solution at low temperatures and permitting the fatty acids or derivatives thereof to precipitate out at low tempera-. tures. Examples of such solvents include, inter alia, petroleum hydrocarbons, such as, gasoline,

kerosene, heptane, mineral spirits, etc.; aromatic hydrocarbons, such as, benzene, toluene, xylene,

etc.; alcohols, such as ethyl alcohol, methyl alcohol, isopropyl alcohol, etc.; ketones, such as acetone, ethyl methyl ketone, cyclohexanone, etc.; chlorinated hydrocarbons, such as, ethylene dichloride, trichlorethylene, etc. The tall oil may be in a crude or a partially or completely refined state at the outset; moreover, the tall oil may be in its usual acid form and composed essentially of a mixture of rosin and fatty acids. The

tall oil may also be used in its partially or com-- pletely esterifled-form, i. e., the fatty acids in the tall oil may be esterified with a monohydric aliphatic alcohol, preferably containing not more than 5 carbon atoms, whereby the rosin acids remain in their acidic form, or both the fatty ature range ,of about 5 C. to -70 C. vIt is obvious, of course, that temperatures outside of this range may also be operative to carry out the objects of the invention. The degree of cooling will be varied according to thenature of the solvent used and according to the form in which the-fatty and resinous materials occur. ,Moreover, the degree of hydrogenation of the tall oil constituents will play an important role in determining the time and temperature under which precipitation will be effected. The precipitated fatty acids or esters are removed from the solvent solution by any suitable means including centrifuging and filtration. The precipitated prodand rosin acids may be in'their esterified form.

The tall oil in any of itsvaforementioned forms may be subjected to varying degrees of hydrogenation before the chilling step, depending upon the type of end products desired. For example, the fatty acids found in tall oil comprises essen tially oleic, linoleic and linolenic acids, the latter two of which are highly unsaturated as compared to oleic acid, which contains only one double bond. The solubility of the highly unsaturated acids-such as linoleic and linolenic acids and their esters is somewhat comparable to the rosin acids and they remain in solution along with the rosin acids during the chilling operation during which the oleic acid or its esters precipitate out. Such a result in certain cases is desirable, i. e., to remove the oleic acid and recover the mixture remaining in the solvent, which comprises essentially rosin acids and linoleic and linolenic acids or their esters. From this latter mixture the unsaturated fatty acids may be separated from the rosin acids by anysuitable process including those aforementioned. Moreover, this mixture of rosin acids and unsaturated fatty acids may be used as such in the preparation of other products such as drying oils, which is to form the subject matter of another application.

Where it is desired to substantially completely recover the fatty acids in a more saturated form from the rosin acids, the original tall oil fatty ucts after removal are preferably washed with a suitable solvent, 1. e., the same solvent as used in the process, and preferably at substantially the same temperature at which the precipitating operation was carried out.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following examples, which are given-merely to illustrate the invention and are not to be construed in a limiting sense. 1

Example I 100 gms. of distilled tall oil (having arosin content of 32%) were dissolved in 650 ml. of acetone and cooled to 60 C. for 1 hour. The oleic acid fraction which has crystallized out is then washed with 350 ml. of fresh acetone which has previously been cooled to -60 C. 40 gms. of fatty acids were obtained which consisted chiefly of oleic acid having an iodine value of about 80 and being practically free from rosin.

From the filtrate the solvent was distilled off and the residue consisting mainly of rosin, linacids or esters are subjected to partial or com- 'the fatty acids will be converted into stearic acid or a mixture having an average iodine value of about 10 or less. The tall oil in any of its aforementioned formsmay be subjected to hydrogenation either before or after it has been dissolved in the desired solvent; moreover the hydrogenation may be effected before esterification in those oleic and linolenic acids was esterifiedby heating 50 gms. of it with 5.5 gms. of anhydrous glycerol at such a rate that the temperature gradually rose and reached 280 C. at the end of the sixth hour. The product thus obtained has excellent film-forming properties and may be used in the manufacture of varnishes as a substitute for linseed oil and ester gum.

Example 11 gms. of distilled tall oil were-dissolved in 700 ml. of ethyl alcohol. The solution was maintained at 60 C. for two hours, and the crystallized fatty acids were filtered and washed with fresh alcoholwhich had previously been cooled to 60 C. The filter cake was freed from any residual alcohol by vacuum distillation. 42 gms. of rosin-free fatty acids were obtained having an iodine value of 71.5 and an unsaponiflable content of 1.8%.

To the above filtrate there was added 0.35 gm. of sulphuric acid and the mixture was refluxed for four hours. The sulphuric acid was then neutralized with an equivalent quantity of caustic soda and the excess alcohol was recovered by vacuum distillation. The residue was then dissolved in 200 ml. of commercial heptane and caustic soda of 12% strength was added with rapid stirring in an amount -l%'in excess of that needed to neutralize the rosin acids. The rosin soap which settled to the bottom of the vessel was then drawn ofif and was washed once with 100 ml. of heptane. The solution of the ethyl esters in heptane was then washed with water until the last traces of soap had been removed and finally the heptane was distilled oil rated fatty acids.

- to recover the ethyl esters of the highly unsatu- The rosin soap was then dissolved in water and split with sulphuric acid to recover the rosin in a free state.

Example III Distilled tall oil was hydrogenated under a pressure of 10 atmospheres and at a temperature of 120 C. for one-half hour using 2% of nickel 2 as a catalyst. Analysis of the product showed that practically all of the highly unsaturated acids had been selectively andpartially hydrogenated to oleic acid, while the oleic acid and the rosin originally present had either not or only very slightly reacted with the hydrogen. The fatty acids separated by analytical means, i. e., by the esterification and alkali wash method had an iodine value of 89.7, comparing favorably with that of oleic acid of commercial quality. 100 gms. of the partly hydrogenated product were dissolved in 800 ml. of acetone and cooled to 60" for 2 hours. The oleic acid which had crystallized out was filtered off and washed with 400 ml. of fresh cold acetone. 63 gms. of oleic acid were obtained.

The rosin was recovered from the filtrate .by distilling off the acetone.

- Example IV Distilled tall oil (having a rosin content of 32%) was hydrogenated for two hours at a pressure of 120 atmospheres and at temperatures ranging from 150 C. to 200 C. using 2% nickel as a catalyst. 100 gms. .of the hydrogenated product which had an iodine value of 28.1 and a titer of 524 C. was dissolved in 1000 m1. of f methanol. The solution was cooled at 6 C. for 8 hours and the precipitated fatty acids were then filtered off and washed three times with 100 ml. portions each of methanol which had previously been cooled to 6 C. The fatty acids thus obtained were substantially free from rosin and consist of a pure white solid having a melt} ing point of 57 C.

The filtrate upon distillation of the solvent yielded a heavy viscous fluid of light-brown color consisting chiefly of the rosin, some unsaponiflable matter and a small portion of fatty acids.

Erample V,

The fatty acids in 100 gms. ofdistilled tall oil were esterified by refluxing for three hours with ml. of methanol and 2 gms. of sulphuric acid. Th product ,(after distilling off the excess alcohol and washing out the sulphuric acid) was composed of methyl esters of the fatty acids,

then filtered oil and washed four times each. with portions of 70 ml. acetone cooled to 18' C.

Thefilter cake consisting of themethyl esters of the fatty acids isa pure white solid below room temperature and upon analysis it showed a rosin content or 32% and an iodine value of 9.7.

The rosin was then recovered from the filtrate by distilling oi! the acetone.

Example VI gms. of the'methyl esters of tall oil, which were prepared by completely esterifying tall oil under pressure with methanol, were hydrogenated to .an iodine value of 18.5. The hydrogenated product was then dissolved in 600 ml. of ethylene chloride and cooled at 18' C. for 12 hours. The

' solid methyl esters of the fatty acids were then filtered off and washed severaltimes with cold ethylene chloride. The methyl esters thus recovered had a rosin content of 1.9%.

The methyl abietate in the filtrate was then recovered by distilling oilf the solvent.

Example VII In a closed vessel which was provided with a reflux condenser, 100 gms. of distilled tall oil having a rosin content of 35% were heated with 11 gms. of anhydrous. glycerol at such a rate that the temperature rose gradually to 280C. during six hours. The triglyceride of tall 011 thus obtained (having an acid value of 3.0) was then hydrogenated at a pressure of 'l atmospheres and at a temperature of to C. using 2% of nickel as a catalyst. The hydrogenated 7 in the purview of the inventionto employ the process for separating resinic acids from fatty acids present in any mixture.

Since certain changes may be made in carrying out the above process without departing;

from the scope of the invention, it is intended that all matter'contained in the above description shall be interpreted as illustrative and not in a limiting sense.

' It is also'to be understood that the following claims are intendedto cover all the generic and specific features of the invention herein described, and all statements of the scope of the invention, which as a matter of language might be said to fall therebetween.

6% of .unsaponiiiable matter and 24% of. free rosin. This'mixture was thenhydrogenated for 2 hours at a pressure of 140 atmospheres and at a temperature Cf'170 C. in presence of 3% of nickel as a catalyst.

100 gms. of the hydrogenated product which had an iodine value of 25.4 were dissolved in 750 m1. of acetone and cooled at -18 C. overnight. The precipitated esters of the fatty acids were Having described my invention, what I claim as new and desire to secure by Letters Patent is: I 1. A process of treating hydrogenated tall oil to separate fatty acids therefrom which comprises dissolving tall oil which has been bydrogenated to the extentwherein the. original unsaturated fatty acids, more unsaturatedth'an oleic acid, have been converted at least to oleic acid in asuitable solvent therefor, decreasing the temperature thereof to eflect precipitation of fatty acids and removing the precipitated fatty acids from the remaining solution.

2. A process of treating tall oil to separate oleic acid therefrom which comprises converting the linoleic and linolenic acids in tall oil to oleic acid by hydrogenation, dissolving the hydrogenated oil in a suitable solvent therefor, decreasing the temperature to effect precipitation of oleic acid and removing the precipiitated acid from the remaining solution.

3. A process for treating tall oil to separate fatty acids therefrom which comprises hydrogenating tall 011 to convert the unsaturated fatty acids into saturated fatty acids, decreasing the temperature of the resulting hydrogenated oil in the presence of a solvent therefor to effect precipitation of the fatty acids and removing the precipitated fatty acids from the remaining solution.

4. A process for treating tall oil to separate the fatty acids therefrom which comprises dissolving the tall oil in a suitable solvent therefor, hydrogenating the fatty acids in the tall oil solution to the extent wherein the original unsaturated fatty acids, more unsaturated than oleic acid, have been converted at least to oleic acid, decreasing the temperature of the solution to effect precipitation of fatty acids and removing the precipitated fatty acids from the remaining solution.

5. A process of treating tall oil to separate fatty acids therefrom which comprises hydrogenating the-fatty acids of talloil under the influence of heat and pressure to the extent wherein the original unsaturated fatty acids, more unsaturated than oleic acid, have been converted at least to oleic acid. dissolving the hydrogenated product in acetone, decreasing the temperature of the solution to effect precipitation of the fatty acids and removing the fatty acids from the rosin-acetone solution.

6. A process of treating tall 011 to separate the fatty acids therefrom which comprises converting the fatty acids in tall oil to their substantially completely saturated form by hydrogenation, dissolving the resulting mass in methanol, cooling the solution to a point below 0 C. to eifect precipitation of the fatty acids and removing the precipitated fatty acids from the remaining methanol-rosin solution.

7. In a process of separating fatty acids from tall oil which has been hydrogenated to the extent wherein the original unsaturated fatty acids, more unsaturated than oleic acid, have been converted at least to oleic acid, the step which comprises chilling a solution of such hydrogenated tall oil in an organic solvent therefor to eifect precipitation of fatty acids.

- ERNEST SEGESSEMANN.