US2506473A - Metod of obtaining fatty alcohols from their esters - Google Patents

Description

AMaly 2, 1950 s.' STEINBERGER- METHOD 0F OBTAINING FATTY ALcoHoLs FROM THEIR ESTERS Filed June 1o, 1948.

2 Sheets-Sheet 2 TTORNEYS Patented May 2, 1950 METHOD OF CBTAINING FATTY ALCOHOLS FROM THEIR ESTERS Samuel Steinberger, Brooklyn, N. Y., assignor to The Richards Chemical Works, Jersey City, N. J., a corporation of New Jersey Application .lune 10, 1948, Serial No. 32,102

12 Claims.

This invention relates to an improved method for obtaining higher fatty alcohols from their esters as found in sperm oil, spermaceti, waxes, and other esters of alcohols containing S to carbon atoms or more and including both natural esters (waxes, etc) and synthetic esters of such high boiling fatty alcohols with fatty acids.

Heretofore the principal method for recovering such higher alcohols from their esters has consisted of saponifying the esters at necessarily elevated temperatures, with essentially anhydrous, strong alkalies such as caustic soda, caustic potash, or mixtures thereof or calcium hydroxide, followed by distillation with dry steam under reduced pressures and at relatively high temperatures. The still bottoms resulting from such distillation are usually of high softening.

point and high Viscosity and must be removed from the still at an elevated temperature.

The present invention provides an improved process for obtaining higher fatty alcohols from their esters in which the successive operations of saponiiication, distillation and removal of residues are facilitated by the employment of a high boiling, water-miscible solvent which is a solvent for the fatty alcohols and the soap formed during the saponication, for example, an ether-alcohol such as triethylene glycol and the like.

The improved process in which such high boiling, water-miscible solvents are used has very practical advantages. The employment of such solvents lowers the temperature required for saponification and permits saponification to be effected within a reasonably short period of time and lowers the softening point of the residual soap mass resulting from the distillation of the fatty alcohols therefrom. The use of such high boiling solvents also promotes the distillation of the fatty alcohols from the saponied esters and gives a distillate containing both the fatty alcohols and solvent. The water-miscible properties of the high boiling solvent enables strong aqueous caustic alkali solutions to be employed for the saponification, as well as solid and essentially anhydrous alkalies. The utilization of such watermiscible solvents also permits alcohols to be separated from admixed high boiling solvent by adding water to form an aqueous-solvent layer in which the fatty alcohols are insoluble. The presence of the high boiling water-miscible solvents is also advantageous in the saponication residue, which can be diluted with water to form an aqueous solution of soap and solvent and then acidined to set free the fatty acid from the soap and form an aqueous solvent solution which also contains salt.

. The present invention includes improvements in the saponification operation, in the distillation operation, in the residual soap treating operation, in .the separation of distilled fatty alcohol from high boiling solvent, and in cyclic operations in which the high boiling, water-miscible solvent is separated from its aqueous solution for reuse in the process.

The high boiling solvents used have boiling points or have a boiling point range similar to that of the higher fatty alcohols, for example, a boiling point range under ordinary atmospheric pressure of around 200 to 350 C. The high boiling solvents may have a boiling point somewhat higher than that of the fatty alcohol to be distilled or somewhat lower than that of the fatty alcohol. And where the ester saponied gives high boiling alcohols of different boiling points the solvent may have a boiling point higher or lower or between those of thealcohols. The high boiling solvents used have such a high boiling point that the distillation of the higher fatty alcohols is at a temperature such that the saponiiication mixture in the still is anhydrous, and the distillation results in the production of an anhydrous soap residue diluted with the high boiling solvent, while the mixed distillate of higher fatty alcohol and solvent is also anhydrous, except for the presence of some water which may be present during the saponication and which may be removed during the early portion of the distillation.

The solvents used are not only high boiling, but are also water-miscible. Among such high boiling water-miscible solvents are included various members of the group of ether-alcohols such as polyalkylene glycols and alkyl ethers thereof as well as high boiling water soluble polyamines such as polyalkylene polyamines, and alkylolamines such as triethanolamine. Among such high boiling solvents may be mentioned ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, butylene glycol, ethoxy triglycol, dimethoxytetraglycol, triethylene tetramine, tetraethylenepentamine, triethanolamine, amino ethyl ethanolamine, methyl diethanolamine, etc.

Where the fatty alcohols have a boiling point range around 200, the high boiling water-miscible solvents advantageously have a similar boiling point. With esters such as those of sperm oil and spermaceti, the alcohols from which have higher boiling points, higher boiling solvents are advantageously used.

The solvents in some cases permit distillation of the fatty alcohol to take place at a temperature lower than that at which either the alcohol or the solvent alone will distill, apparently forming constant boiling mixtures. Even where such constant boiling mixtures are not formed the alcohol and solvent will be distilled together and the distillation of the solvent will promote or facilitate the distillation of the alcohol.

The solvents used promote the saponliication.

An advantageous method of carrying out the process is by using strong aqueous solutionsl of sodium or potassium hydroxide instead of the solid 'and essentiallyh anhydrous alkales. With water vmiscible high'boiling solvents the saponif`ication can be carried 'out by employing such strong, aqueous caustic solutions without appreciablyV affecting the saponication rate or the quality of the"saponi'icatio'n, while the mixing and handling of the reaction mixture is facilit'ated.

The saponication step and the subsequent distillation step 'of the process can be carried out in the same vessel which will serve iirst as reactionvessel at a lower temperature and later as la still vat a higher temperature. processing time may be reduced in this case by beginning the distillation before the saponincation isbompleted, with the two processes pro ceedin'g simultaneously. The apparatus or vese sels or Vstills employed will be provided with suit-` able heating means and with stirrers or agitators. Where saponiiication' is carried out in one vessel and distillation in another, the saponiiication may be completed before the distillation begins or the incompletely saponied charge may be transferred to the still and the saponication completed during the early period of distillation.

The distillation of the high'boiling fatty alcohols is carried out at pressuresbelow atmospheric in order to take advantage of. the low temperatures at which the charge maybe maintained in the rluid state aswell as tov insure greater heat economy. Other things being equal,Y the. degree of vacuum required is` preferablythat which will yield a high ratio of fatty alcohol to solvent in the distillate.

In general the amount ofasolvent present in the sapoiiication step maybe kept to a minimum, with the use of. sufcient solvent to give a thinly iuid mixture for saponiflcation, but without undue dilution of the reaction mixture with. sol.- vent. During. the course of the distillation, however, more solvent isy advantageously added as requiredto make up for. that which is distilled with the fatty alcohol and to insure thatall of the fatty alcohol is distilled from the charge. Practically quantitative yields` of alcohol could be obtained. During the early or main portion of the distillation a high ratio of fatty alcohol to solvent is distilled. After most of the fatty alcohol has been distilled, during the last portiongof the distillation, the I'distillate is largely solvent; and this pOrton of the distillate is advantageously set aside and reused in a succeedingbatch. The distillation is remarkable for its almost complete freedom from foaming until the still bottoms contain. a 4low concentrationof solvent. "lhe"z distillationl residue can be freed from most of its,` solvent buty suiiicient solvent should be. left to insure that the residue is still iiuidwhencooled:.IY The distillation residue The total is an anhydrous soap diluted with anhydrous solvent.

After the distillation, the residue in the still is cooled to a point where it is still fluid, which is the case at moderate temperatures, and the process is in this respect distinguished from processes carried out in the" absence of a solvent where the residue is highly viscous even at 200 C. or higher in the case of s permacetl. After cooling the fluid, anhydrous residue is added to aqueous acid, or is added to water with subsequent addition of acid, to set free the fatty acids which separate as a layer on top of the aqueous solvent layer. The water-miscible solvent readily mixes with the added water. Any solvent separating with the fatty acids is readily washed out to give a substantially solvent-free fatty acid layer. The aqueous solvent` mixture containing salt from the acidification' of the soap is advantageously treated thereafter' to recover the solvent for reuse.'

The distillate is advantageously collected in two separate parts, the rst and main part containing most of the fatty alcohol mixed with anhydrous solvent; and the latter part being mainly solvent with a small amount of fatty alcohol. This second amount of anhydrous solvent with a small amount of fatty alcohol is advantageously returned to the process and used as a solvent in treating a further. batch of ester. The main portion of the, distillate is advantageously treated by adding water which extracts the solvent and separates the insoluble fatty alcohol, giving a fatty alcohol layer and an aqueous solvent layer. The fatty alcohol fraction, after washing with fresh Water, is of aV high grade. The aqueous sc ,Jlvf-:nt` mixture isthen distilled to remove the waterv and give anhydrous solvent for return to the process.

Ehe separation ofthe solvent andl fatty alcohol can be carried out by the use ofv organic materials such as ligroin, etc. which exert a selective solvent action and extract the alcohol from the` high boiling solvent. But for practical operation, the use of water to separate the watermisciblehigh boiling solvent from the high boiling fatty alcoholis a more advantageous method.

The nature of the process will be further described connection with the accompanying drawings which illustrate, in a somewhat conventional and diagrammatic manner, in Fig. l, an arrangement of; apparatus and processing steps, and in Eig. 2'-, a flow sheet, but it will be UBFeFSPQQd; that; the iliverltiorl.V is. not limited thereto.

Referring tov the4 diagrammatic arrangement shown in Eig. 1, acauvstic; liquor. supply tank is conventionallyshown at l, supply, tanks for ester at2` and 3, for sperrngoiland.spermaceti, respectively, as. theesters'. to; betreatecl and a solvent supply is, indicatedconventionally at d. These supply, tanks, are connected through pipe connections havingscontrol-valves therein and meters 5, therein to.the,sapQniiier-.-and still E, having stirrer. 'i thereinand providedwith heating `means (not, shown), The. arrangement vis, such that -a suitable. charge4 of esterasuch as sperm oil or spermaceti with anfappropriate charge-of caustic liq'uorand solvent caribe suppliedinitially to saponiiier, fon theA saponicationstep of the process; and additional solvent can: be supplied as` required, duringL the.V subsequentdistillation step.

The Adistillate fronihe stillA 6: is condensed in the. 001.1@ensei,- gfand; collected yin thezrecever.. 9

which is connected through the line I with a vacuum pump (not shown) by which a high vacuum can be maintained on the still during distillation. From the receiver 9 the main portion of distillate containing most of the high boiling fatty alcohol is collected in the concentrated distillate storage receptacle II, while the latter part of the distillate containing mainly solvent and with a small amount of fatty alcohol is collected in the dilute distillate storage tank I2 and returned through the line I3 to be added to the solvent in the tank 4, so that this solvent can be used over again in a subsequent charge and its fatty alcohol content subsequently recovered.

The concentrated distillate in the form of an anhydrous mixture of high boiling solvent and high boiling fatty alcoho1 passes from the tank II through the line I4 to the proportioning pump I5 and then through the line I6 to the bottom of the tank Il, where dilution takes place with separation of alcohol and a concentrated aqueous solvent layer. The alcohol passes through line 24 to the bottom of a second separating tank I9 where the alcohol is further washed with water to remove solvent from it and the resulting crude fatty alcohols pass through the line to the storage tank 2 I.

Water is supplied through the proportioning pump 22 and passes through the line 23 to the top of the tower I9 Where the fresh water serves to wash the fatty alcohol passing upwardly therethrough, to remove water-miscible solvent from it. The resulting dilute aqueous solvent solution passes through the line I8 to the top of the tower I1 where it serves to effect the preliminary separation of the solvent-alcohol mixture into an upper alcohol layer and a lower layer of concentrated aqueous solvent. The concentrated aqueous solvent is drawn olf through the line 25 to the dewatering column or still 26, where the mixture is heated and water distilled through the line 21 and from which the resulting anhydrous solvent is returned through the line 28 to the solvent storage tank 4.

After the distillation of the flatty alcohol from the still is completed, and after part of the remaining solvent has been removed from the still, the residue, made up of the anhydrous soap and sufficient solvent to give a liquid mixture, is discharged through the line 30 to the acidifying vat 3| where it is treated with acidified water to set free the fatty I'acids from the soap, and to form an aqueous solvent layer containing the salt formed. r["he crude fatty acids are drawn off through the line 32 to the crude fatty acid storage tank 33. The brine containing the salt and the organic solvent in aqueous solution is drawn off through the line 34 and is also subjected to concentration to distill the water from it and to separate the salt from it and to give solvent which can also be returned for further use in the process.

In the alpparatusand diagrammatic arrangement of process steps illustrated and above described, and in the flow sheet of Fig. 2, the solvent and caustic will be charged to the agitated salponilcation kettle through meters o-r weighing tanks and heated and the ester from the storage tank added and the saponication then conducted more or less to completion. In the arrangement shown in Fig. l the mass is distilled in the same vessel, although it could I,be transferred to a separate still as shownV in Fig. 2. or stored for treatment in a continuous 6 distillation system. The distillate is diverted either in the concentrated storage tank for further treatment to separate the fatty alcohol from the solvent and to recover the solvent for reuse; or, in the later stages of distillation the dis-- tillate may be diverted into the tailings or dilute distillate storage receiver from which solvent for the next sraponication batch may be drawn, or returned to the saponier as shown in Fig. 2.

"In the course of the distillation additional solvent will be drawn from the storage tank as required to replace the solvent driven olf with the fatty alcohol and to insure that the charge in the still is freed from all of the fatty alcohol. The residue from the still may then be cooled as desired and dropped into the laciclied water to liberate the fatty acids from the soap and to give a crude fatty acid as one of the products of the process. 'Ilhe lye or brine from which the fatty acids are separated and which contain salts, water and solvent may be concentrated to remove water and precipitate the salts and to recover the solvent for reuse.

'Ihe concentrated distillate from the still may be treated with water either batchwise or continuoirsly to separate fatty alcohols from the solvent. In the arrangement shown in Fig. 1 the distillate is passed successively through the countercurrent extraction towers I'I and lI9 against water with regulation of the amount of water and distillate by the proportioning pump. The washed, crude alcohol goes to the storage tank from which it may be removed for drying, fractionation or immediate use. The diluted solvent is then passed through the concentrating column where it is freed from water and the solvent recovered and returned to the process.

The cyclic nature of the Iprocess and the inter-- relation of the various steps when carried out; in a cyclic manner is illustrated in the drawings.` It will be seen that the same high boiling, watermiscible solvent is recovered and used in a cyclicv manner. From the drawings, and from the foregoing description, it will be seen that the high boiling solvent is added :and is :present during saponiication to promote the saponification; that it is also present and is used during the distillation to promote the distill-ation; and that advantage is taken of the water-miscible properties of the solvent to facilitate separation of the fatty alcohols therefrom and also to facilitate the acidification of the soap and the recovery of fatty acids therefrom; while the solvent, separated as an aqueous solution, is freed from water and returned to the process in a cyclic manner.

The invention will be further illustrated by the following specific examples lhut is not limited thereto.

Example 1.-A mixture of 400 parts of triethylene glycol and 40 lparts of 48 Be. NaOH (assaying 47.1% NaOH and 0.8% NaZCOa) was heated to C., whereupon 200 parts of spermaceti was added gradually. The mixture was then heated with agitation to 95 C. for one and one-half hours. Titration of an aliquot at this point indicated that the saponificationy was essentially complete.

202 parts of the mixture containing 28.4 parts of fatty alcohols was transferred to a distilling vessel and distilledy lat a pressure of 8-12 mm. absolute. Additional glycol was added at intervals. A first cut distilling between 146 and 160, and amounting to 122 parts, contained 19.9 parts or 70% of the theoretical. Further cuts, total.

7 ling 188 parts, brought the recovered alcohol to 28.4 parts, or approximately 100%.

To the above distillate, water was added suficient to bring the glycol concentration to a 70 aqueous solution (70% solvent and 30% water); the alcohols separated almost quantitatively from the solution, and contained-only a small amount of glycol and Water. This wasy removed by 'a second wash.

Example 2.-To a mixture of 330 parts of tetraethylene glycol and 54 parts of 40% aqueous NaOH at 70 C., 210 parts of sperm oil was added gradually, and the mixture was heated to 90 C; for about two hours. Saponification was essentially complete.

To 559 parts of this product corresponding to 196 parts of sperm oil, was added 100 parts more tetraethylene glycol, and the mixture was dis-y tilled at ia pressure of 16i2 mm., between 180 and 205 C. 95 parts of distillate contained 37 parts of fatty material. As the distillation proceeded, more of the glycol was introduced; sucmaterial, totaling 40.3% of the sperm oil taken.

Addition of water to the distillate caused a separation into two layers, the upper of which contained practically all of the fatty alcohols.

Example 3.-210 parts of sperm oil, 400 parts of triethanolarnine'and 54 parts of 40% NaOH were heated for one and one-half hours at 90-'100 C. Distilledat -16 mm. between 18S-207 C. a main fraction containing 42% of fatty alcohols, amounting to 37.5% or the sperm oil taken, was removed; further distillation yielded a less concentrated cut, bringing the total yield to 41.8% on the weight of the sperm oil.

Addition of water to the distillate caused a separation into two layers, the upper of which contained practically all of the fatty alcohols.

The above examples illustrate the saponiiication and distillation steps of the process and the .separation of the fatty alcohols from the high boiling wateremiscible solvent. The recovery of the solvent for reuse and the acidification of the .soap to recover fatty acids are not included in the :above examples.

it will thus be seen that the present invention 'provides an improved method for recovering high boiling. fatty alcohols from their esters in which 'high boiling water-miscible solvents are used to promote the saponii-lcation and subsequent dise tillation; and that such solvents are advantage ously used in a cyclic man-ner. It will further be seen that the use of-such high boiling watermiscible solvents has many advantages in profmoting the saponication and distillation as well as the subsequent treatment of distilled residue and the recovery of the distillate, Iadvantage bee ing taken of both the high boiling properties of the solvents during the distillation and of the water-miscible properties of the solvents to promote separation ci the reaction products.

I claim: v

1. The method of recovering high boiling fatty alcohols containing 8 to Y2G carbon atoms or more from their esters which comprises saponifying such esters with an alkaline agent inthe pres'- ence of a water-miscible solvent which is al sole vent for the fatty alcohols' an'd soap' formed by the saponiication and which has a boiling point withinV the range from about 200' to about 350 C.,

and then distilling the mixture to obtain a codistillate containing suchl solvent and the fatty alcohols.

2f. The improvement in the methodof recover-i ing of fatty alcohols containing 8 to 20 carbon atomsfrom their esters by saponifying such esters with an alkaline agent and then distilling the alcohol from the s-aponilcation mixture, which comprises promoting the distillation of the fatty alcohol by carrying out such distillation of the saponication mixture with a water-miscible solvent which is a solvent for the fatty alcohols and soap formed by the saponication and which has a boiling point within the range from about 200 to about 350 C., to obtain a co^distillate containing such solvent and the fatty alcohols.

3. The process according to claim 1 in which the co-distillate of water-miscible solvent and fatty alcohols is treated with Waterv to separate the fatty alcohols and form an aqueous solvent mixture and in which the solvent is recovered from such aqueous mixture by distillation for further use in the process.

4. The process according to claim 1 in which the residue from the distillation, in the form of an anhydrous mixture of soap and solvent, is treated with acidined water to set free the fatty acids and form an aqueous-solvent-salt mixture, followed by separation ofA the solvent from the water and salt and return of the solvent to the process.

5. The process according to claim 1 in which the cc-distillate of solvent and fatty alcohols is obtained in the form of a C13-distillate with a'high content ci" fatty alcohols and a nal distillate of solvent with a small amount of fatty'alcohols; with return of the seconddistillate for use as a solvent in the further carrying out of the saponication step of the process.

The process according to claim 1 in Which the co-distillateof solvent and fatty alcohol is treated with Water to separate the fatty alcohol and form an aqueous-solvent mixture by passing the distillate through successive treatments of counter-now with waterfto form a concentrated aqueous solution of the solvent. and to wash the alcohol free from solvent, followed by distillation of the aqueous solvent and return of the resultingv anhydrous solvent to the process.

7. The process according to claim l'in which the water-miscible solvent is a polyalkylene glycol solvent.-V

8. The process` according to claim 1 in which the water-miscible solvent is a polyalkylene glycol ether solvent.

Y 9. Thev process according to claim 1 in which the water-miscible solvent is triethylene glycol.

10. The process according to claim 1 in which the water-miscible solvent is a polyamine.

11. The process according to claim 1 in which the water-misci'ele solvent is an alkylolamine.

12. The process according to claim- 1 in which additional solvent is admixed with the mixture being distilled in order to maintain such mixture in a iiuid condition without undue dilution of said mixture. v

SAMUEL STEINBERGER.

REFERN'CES CITED VThe following references are oi record in the file of this patent:

UNITED STATES PATENTS Number Name Date I 1,814,654 Youtz July 14, 1931 1,967,319 Moore et al July 24', 1934 2,021,926 'sexton -n n Nov. 26, 1935 2,245,538 Thurman che- June-10, 1941

Claims (1)

1. THE METHOD OF RECOVERING HIGH BOILING FATTY ALCOHOLS CONTAINING 8 TO 20 CARBON ATOMS OR MORE FROM THEIR ESTERS WHICH COMPRISES SAPONIFYING SUCH ESTERS WITH AN ALKALINE AGENT IN THE PRESENCE OF WATER-MISCIBLE SOLVENT WHICH IS A SOLVENT FOR THE FATTY ALCOHOLS AND SOAP FORMED BY THE SAPONIFICATION AND WHICH HAS A BOILING POINT WITHIN THE RANGE FROM ABOUT 200 TO ABOUT 350*C., AND THEN DISTILLING THE MIXTURE TO OBTAIN A CODISTILLATE CONTAINING SUCH SOLVENT AND THE FATTY ALCOHOLS.

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