US2288947A - Conversion and separation of the constituents of organic mixtures containing both fatty and resin acids, particularly tall oil - Google Patents

Description

"Patented July 1, 1942 A CONVERSION AND SEPARATION OF THE CONSTITUENTS OF ORGANIC MIXTURES. CONTAINING BOTH FATTY AND RESIN ACIDS, PARTICULARLY TALL OIL Frederick 11. Gayer and Charles 2. Fawkes, cm-

cago, Ill.,-assignors to Continental Research Corporation, Chicago Heights, 111., a corporation of Illinois No 1mm. Application July 17, 1939,

Serial No. mp1s 9Claims.

This invention relates to a process for the separation of the major constituents of organic mixtures or oils containing-both fattyand resin acids aration of the fatty and resin acid portion of ,tall oil but obtain as a result of that separation derivatives of fatty and resin acids respectively,

and especially to the clean, sharp and economic separation of the fatty and resin acids from such mixtures or oils, and particularly from tall oil. A more particular feature of our invention is the recovery of fatty nd resin acids in the form 01 ttheir commercially useful and valuable derivaves. Tall oil is a by-product of sulphate pulp or kraft paper manufacture and is composed preponderantlyof fatty acids, resin acids, unsaponifiable matter and coloring impurities. ,The

unsaponifiable matter is composed of hydrocarbons and cyclic alcohols belonging to the group of phytosterols of which tall oil is an unusually rich source. 1

In our co-pending applications Serial No. 169,655 and No. 169,656 the latter now issued as Patent No. 2,223,850, both filed October 18, 1937,

we have disclosed processes for the refining oi crude tail oil and obtaining valuable by-productsv thereof. According to those applications we remove the coloring substances from .crude tall 01. and recover the commercially valuable phytosterol ina substantially quantitative yield and obtain a refined oil of light, color and containing only a fraction of the unsaponifiable matter originally present. Crude tall'oil also can be refined'by distillation at reduced pressure. A greater portion of the fatty and resin acids and commercially more valuable than either fatty or resin acids in themselves.

Numerous processes have been prepared relating to the separation of the components of tall oil, and one such process is disclosed in our copending application Serial No. 169,654 now issued as Patent No. 2,166,812, which'deals with the separation of the fatty and resin acids by a procas involving esterification df the fatty acids, neutralization of the resin acids with an alkali metal base and separating the fatty acid esters from the resin acid soaps by means comprising furfural and water and whereby we obtain as final products fatty acid esters and after acidifying the resin acid soaps, the free resin acids.

- In distinction from our aforementioned process the present invention comprises esterification of the fatty acids, converting the resin acids into their aluminum salts and separating the fatty acid esters from the aluminum resinates. By this process We obtain high grade fatty acid esters and aluminum resinates, both products of considerably greater commercial value than either tall oil or fatty and resin acids in themselves.

In the present process, as in Serial No. 169,654,

- our Patent No. 2,166,812, we have taken advanof the unsaponifiable matter distill over, the.

coloring matter and phytosterol remaining in the still residue. The'tall oils refined by distillation are also of a considerably liahter color than the crude oil and also are essentially mixtures of fatty and resin acids with a rather high proportion of unsaponifiable matter.

Relatively. little-use has been made so far of crude or refined tall oil, as the simultaneous pres-- ence of both fatty and resin acids is of great disadvantage. These components in themselves, however, as fatty and resin acids respectively are of great commercial'importance. A large number of useful compounds are derived from these acids and find innumerable industrial applications. A .processwhich. effects a sharp separation. of the components of tall oil is, therefore, of great commercial value, especially in view of the .vast potential supply of tail of]. resultl s -from the increasing importance of the sulphate process for, P per making. According to the process of the present invention hereinafter set forth we not only effect a clean andsharp septo b low the boiling point, of the. alcohol used in tage of the fact that the fatty acids in tall 011 may be readily esterified with monohydric, aliphatic alcohols, such as methyl-, ethylor higher alcohols, whereas, given the proper conditions, the resinacids remain unchanged. This known chemical principle has been made the basis of a new and useful process of separation and is an integral part thereof," as hereinafter set forth.

That is. the essence of this invention resides in taking together the old process of selective esterification of the fatty acid components carried out under controlled and specified conditions in combination with the new step of converting the resin acids into their aluminum salts and separating the fatty'acid esters from the aluminum may be eflecte'd by several methods, such as refiuxing or otherwise reacting the tall 011 with a monohydric alcohol, such as methylor ethyl alcohol, or a higher monohydric alcohol. The alcohol isv preferably used in excess over that required for the quantitative esterification of the fatty acids. Esterification can be effected at or tion.

the presence of catalysts, such as, for example,

sulphuric acid, or by any other conventional or suitable method. We prefer the esterification method disclosed in our co-pending application Serial No. 284,915, filed July 17, 1939, whereby esterification is effected in the absence of a catalyst at higher than atmospheric pressure. Esterification according to this method produces a mixture of fatty acid esters, resin acids, unsaponifiable matter, excess alcohol and the water formed in the esterification reaction. We then distill off the excess alcohol and the water and obtain a mixture consisting of fatty acid esters, resin acids'and a minor portion of uns'aponifiable matter.

The next step in our process comprises the conversion of the resin acids contained in this mixture into aluminum resinates. We achieve this conversion by what is ordinarily known in the art as precipitation, namely, neutralizing the greater traction residue aluminum resinates which, after driving ofi the solvent, disintegrate into a fine white powder, and a liquid extract which contains a small quantity of aluminum resinates andv some free resin acids which are easily removed from the esters by an alkali wash. Distillation resin acids contained in the esterified mixture,

with an alkali metal base, such as for instance, sodium hydroxide, and converting the alkali resinates into aluminum resinates by reacting them with a solution ofan aluminum salt, such as for instance, aluminum chloride or sulphate. For example, we neutralize the acidity of the esterified mixture with the required quantity of a one-half to one normal solution of sodium hydroxidein water and pour the resulting mixture into somewhat more than the calculated amount of a 0.2 to 0.4 normal aluminum sulphate solution while the mixture is rapidly stirred. There results on the surfaceof the, aqueous layer a pasty or oily layer composed of fatty acid esters and aluminum resinates. Heating of the mixture now causes dehydration of the top layer and subsequent draining of the aqueous layer leaves a crust of a mixture of fatty acid esters and aluminum resinates. This mixture has the consistency of a soft solid with an oily touch, beingessentially a mixture of a solid (aluminum resinates) with an oily liquid (fatty acid esters).

We obtain substantially the same result if instead of reacting the sodium resinate with an aluminum salt solution we react the'mixture of fatty acid esters and resin acids with freshly precipitated aluminum hydroxide suspended in water. On continued shaking or stirring all the resin acids are converted into aluminum resinates. Heating the mixture and separating the solid from the water gives thesame mixture as that obtained by the first method. The reaction with aluminum hydroxide, however, has timedvantage that the volumes of reactants can be kept much smaller than in the case of precipita- The final step of our process consists of the separation of this mixture into fatty acid esters and aluminum resinates. We have found solvent extraction a'convenient method for. achieving this separation. By extracting the mixture with solvents which dissolve the fatty acid esters but are ates entirely free from esters. For instance, the

major portion of methyl alcohol which at ordinary temperatures is a poor solvent for the fatty 'acid esters of tall oil becomes miscible with these esters in all proportions if the temperatureis raised above the critical solution temperature,

which in this case is 33 C. It has, however, substantially no solvent power for the aluminum resinates.

of the esters yields high grade fatty acid esters of light color.

The following example will illustrate our process, although we do not limit ourselves to the conditions as disclosed in this particular example.

v Example The fatty acids contained in a refined tall oil, are esterified with methyl alcohol. Three and one-half kilograms of the esterified mixture are stirred into a quantity of 0.7 normal aqueous sodium hydroxide solution suflicient to neutralize the resin acids. The resulting ester-soap mixture is slowly poured and stirred into an approximately one-third normal solution of aluminum sulphate present slightly in excess over that required to react with the resin acid soaps. Heating of the reaction mixture causes it to solidify and float on the surface of the aqueous layer. After washing with 10 liters of neutral water the mixture is centrifuged to remove occluded water. The dry mixture is now extracted with methyl alcohol. We obtain 1.05 kilograms of aluminum resinate as a fine white powder and 2.40 kilograms of a yellowoil which after exhaustive washing with a dilute sodium hydroxide solution is distilled at reduced pressure. We obtain 2.0 kilograms of pale yellow fatty acid esters.

We claim as our invention:

l. Theprocess of separating fatty acids fro resin acids contained in tall oil, which comprises converting the fatty acids into their alkyl esters, converting the resin acids into their aluminum salts and separating the alkyl esters of the fatty acids fromv the aluminum resinates.

2. The process of separating fatty acids from resin acids contained in tall oil, which comprises converting the fatty acids into their alkyl esters, converting the resin acids into their aluminum salts and separating the fatty esters from the aluminum salts by extraction with a solvent which is substantially a non-solvent for alumi num resinates.

3. The process of separating fatty acids from resin acids contained in tall oil, comprising reacting the tall oil with a monohydric aliphatic alcohol to esterify the fatty acids, converting the resin acids into their aluminum salts and separating the fatty acid esters from d. The process of separating fatty acids from resin acids contained in tall oil, which comprises converting the fatty acids into their alkyl esters, reacting the resultant mixture with a suspension of aluminum hydroxide in water to convert the resin acids into their aluminum salts.

the aluminum removing the water and separating the fatty acid Y esters from the aluminum resinates.

5. The process of separating fatty acids from resin acids contained. in tall oil, which comprises converting the fatty acids into their alkyl esters; neutralizing the resin acids with aqueous alkali, reacting the mixture with a solution of an aluminum salt to convert the alkali resinates into aluminum resinates, removing the water and separating the fatty acid esters from the aluminum resinates. 6. The process of separating tall oil into fatt acids and resin acids, which comprises converting the fatty acids into their alkyl esters, con- I verting the resin acids into their aluminum resinates and extracting the fatty acid esters with a volatile solvent which is substantially a nonsolvent for aluminum resinates, removing the solvent and recovering the fatty acid esters.

7. The process of separating tall oil into fatty acids and resin acids, which comprises converting the fatty acids into their alkyl esters, converting the resin acids into their aluminum res- I a low molecular weight aliphatic alcohol at a temperature above their critical solution temperature, removing the solvent by distillation and recovering the fatty acid esters.

9. In a process of separating tall oil into fatty .acids and resin acids, the step which comprises converting the tall oil into a mixture of alkyl esters of fatty acids with aluminum resinates by esterifying flrstlthe fatty acids with a monohydric aliphatic alcohol and subsequently converting the resin acids into aluminum resinates.

- FREDERICK H. GAYER.

CHARLES E. FAWKES.