DE1177124B - Process for the separation of a mixture of dihydric alcohols having 19 carbon atoms. - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Boarding school Class: C 07 c

German KL: 12 ο -5/03

Number: 1177 124

File number: R 32624 IV b / 12 ο

Filing date: May 4, 1962

Opening day: September 3, 1964

The German Auslegeschrift 1 109 661 describes processes which have as their subject the production of ln-heptadecanedicarboxylic acid by the catalytic addition of CO and H ₂ onto unsaturated C ₁₈ monocarboxylic acids. The separation of the unbranched 1,17-heptadecanedicarboxylic acid from the branched components is also described here, and a procedure based on the use of selective solvents was also explained.

German Patent 1 030 195 and other proposals relate to processes for the production of dialcohols with 19 carbon atoms from unsaturated C ₁ ^ monocarboxylic acids by the catalytic addition of CO and H ₂ , initially aldehyde carboxylic acids and, after hydrogenation, isomer mixtures of C ₁₉ dialcohols .

In the further processing of the C ₁₉ diols, the presence of one or the other component is perceived as a nuisance, since the high stock C ₁₉ dialcohols, which mainly consist of straight-chain components, increase the melting point, while the low stock fractions, for example, make the production of linear polyesters impossible do.

For the production of uniform intermediate products, there is therefore a desire for a flawless one Method for the separation of the high stump parts from the low stump parts.

Several working methods have already become known for solving similar tasks. So can according to German patent 1010 062 the separation of mixtures of high molecular weight alcohols in constituents with different melting points are made by the fact that the mixture of high molecular weight Alcohols dispersed in an aqueous medium and the dispersion using a centrifuge separates, one phase with liquid portion and another phase with suspended solids Alcohols is obtained. The procedure of US Pat. No. 2,234,916 is used in a similar manner. Here wax and oil are supposed to be separated by a hot, aqueous carrier liquid, which makes a division caused by specific gravity. Here, too, separation is carried out by centrifugation. A special apparatus arrangement for the separation of liquid mixtures with different specificities Weight describes U.S. Patent 2,534,210. In each of these known cases, according to the principle of a separation of dispersions or suspensions according to the specific weight worked using centrifuges.

Method for separating a mixture of
dihydric alcohols
with 19 carbon atoms

Applicant:

Ruhrchemie Aktiengesellschaft,

Oberhausen (Rhld.) - Holten

Named as inventor:

losef Meis, Oberhausen (Rhld.) - Osterfeld,

Dr. Karl Büchner, Moers (Ndrh.)

Distillative separation methods are ruled out from the outset for working up the alcohol _{mixtures, since the boiling points of the C 19} diols are not only very high, but also close together.

The separation by means of urea requires a relatively large amount of work and chemicals, while separation by molecular sieves is difficult on an industrial scale.

In the German Auslegeschrift 1 109 661 is a way of working to separate the high stock 1,17-dicarboxylic acids from the deeply stagnant dicarboxylic acids with a total of 19 carbon atoms described by using selective solvents. Trying to this procedure also applies to the separation of the high-volume dialcohols from the low-volume ones Using dialcohols with a total of 19 carbon atoms, it turned out that the process was not transferable. The use of heptane as a solvent gave unsatisfactory results, as did the use higher-boiling unsaturated aliphatics such as iso-octane, diisobutylene and iso-dodecane. A little better, yes the results were still unsatisfactory when using cycloalkanes such as cyclohexane, Terpenes, hydrogenated and substituted aromatics such as decalin and chlorobenzene. Finally it turned out that the best results could be achieved with aromatics, but with very specific working conditions had to be adhered to.

It has been found that when the high-stocking fractions are separated from those present at the same time deep-stocking isomers of a mixture

409 659/426

of dialcohols with 19 carbon atoms, which has been obtained by oxo synthesis and subsequent hydrogenation from unsaturated C ₁₈ monocarboxylic acids, by treatment with selective solvents and fractional crystallization, very good results can be achieved if the mixture of dialcohols is heated with preferably off Dissolves aromatics existing solvents, eliminates the high-stock components by strong cooling, brings the excreted product, which still contains low-stock components, to the solution again in the heat and cools it to a higher temperature than the first cooling temperature, after which the high-stock solid components are isolated.

In this procedure, it has been found that it is advantageous to carry out the first cooling to a temperature between -5 and +5 ⁰ C and the second cooling to a temperature 15 to 25 ⁰ C temperature.

Benzene and toluene have proven to be particularly favorable solvents for this procedure.

The procedure according to the invention is expediently carried out as follows:

Is dissolved at about 70 ⁰ C the mixture of the C ₁ "dialcohols (melting range 50 to 60 ⁰ C) in the four-fold amount of technical benzene or toluene, wherein the toluene is to be given because of the lower pour point of the preference, the solution is cooled (if appropriate after filtration) to +5 ⁰ C., can at this temperature for a few hours of standing, separated at the same temperature the solid fraction off and washed with cooled to +5 ⁰ C toluene, and the crystals dissolved again at 70 to 80 ⁰ C. in twice the amount of toluene and cools to normal temperature (18 to 22 ⁰ C). After separation from the solvent to the mixture employed and the highly faltering C obtained in a yield of 12.5% ₁₉ dialcohols having a pour point 91-98 ⁰ C and a hydroxyl number of 368 (calculated: 373).

In the process according to the invention, the low stock content is obtained from the feed in a yield of about 70% by removing the solvent by distillation. This low stock content shows pour points around 0 ⁰ C and a hydroxyl number of 357 (calculated: 373).

The remaining remainder of the insert is in the solvent used for the separation, which is returned to the separation passage.

The process according to the invention for separating the high-stock C ₁₉ dialcohols from the low-stock isomers can also be carried out continuously in a simple manner, the solvent cycle being designed so that the _{mother solution remaining after the high-stock C 19} dialcohol has crystallized out is fed to a separation column which the solvent is drawn off overhead and returned to the first and second dissolution process, while the low-volume dialcohols with the C ₁₈ monoalcohol are obtained at the bottom of the column. The mother liquor from the second solution process is returned to the first solution process without distillation. Solvent losses are expediently supplemented in the second solution process.

example 1

10 g each of a C ₁₉ dialcohol mixture in 40 ml each of chloroform, isopropyl ether, benzene, toluene and xylene were introduced, heated and allowed to cool. Weight fell from the chloroform solutions after the hot filtration on cooling 10 of a crystalline precipitate from a Schmelzo range of 60 to 80 ⁰ C, while the dissolved in chloroform the product after solvent stripping showed lard-like consistency, thus containing even higher halting play. 15 percent by weight of isopropyl ether was used for

ίο get the same way of working while the dissolved fractions after removal of the solvent a clear liquid with crystalline precipitate revealed. In the case of the solution in aromatics, on the other hand, there were 18% solid fractions with melting ranges of 60 to 85 ° C, while the liquid portions presented clear liquids with no precipitates.

Example 2

200 g of the Cjg dialcohol mixture, as used in the previous example, were dissolved in 800 ml of hot toluene. After the solution had entered, after removing the heating, the mixture was cooled down to 20 ° C. with stirring, which took several hours. Crystals precipitated out and could be easily filtered off from the mother solution. After the precipitate had been sucked dry on the suction filter, it (45 g) was dissolved in a further 180 ml of hot toluene and ^{cooled again to 20 °} C. with stirring. This gave 18 g of a crystallized product (9% of the input) with a melting range of 95 to 98 ^° C. and a hydroxyl number of 377. The work-up of the filtrates gave the following picture:

From this example it can be seen that the separation of the high-stocking C ₁₉ -dialcohols from their low-stocking isomers cannot be effected by recrystallization as is customary in practice, because the melting ranges of the fractions remaining dissolved in the toluene show the presence of straight-chain fractions in the branched-chain fractions.

yield
in g OH number Enamel
Point
⁰ C 1. Filtrate
Toluene flow
1 parliamentary group 497.6
15.0 314 + 13 2 faction 133.0
18.6 357
288 + 11
+ 38 Residue 142.6
8.7 319 about 20 2. filtrate
Toluene flow
Residue

Example 3

200 g C ₁₉ -Dialkoholgemisch was dissolved as hot in the past game in 800 ml of toluene and the clear solution cooled with stirring for 2 hours at +4 ⁰ C. The precipitated solid fraction could be easily separated on a suction filter. The amount

was found to be 150 g (moist). This was dissolved in 600 ml of toluene again hot and allowed to cool with stirring to 2O ⁰ C, with stirring for 2 hours long. +5 ⁰ C) was stirred: in this case a residue of 22 g (dry) with a melting range of 95 to 97 ° C and a hydroxyl number of 368. The work up of the filtrates gave the following image was obtained. In the second stage was again extracted by stirring at -5 ⁰ C, and 49 g lard-like residue was obtained. After repeated dissolution and stirring at room temperature, g (~ 11.5% of ^the input) of a crystallized product with a melting range of 96 to 101 ^° C. and an OH number of 370 were obtained.

lot
in g OH number Enamel
area
⁰ C 1. Filtrate
Toluene flow
1st parliamentary group 384.0
7.5
112.5 281
344 + 12
- 3 2nd parliamentary group 17.4
555.8
11.2 222
315 24 to 39
+ 13 Residue 9.4 265 about 53 2. filtrate
Toluene flow
1st parliamentary group 2nd parliamentary group

B e i s ρ i el 6

The ethyl acetate was prepared from the low-stock C _{19 dialcohols obtained in the previous examples.} At the same time, the ethyl acetate prepared from the total dialcohol-Cjg mixture under the same conditions was used for comparison.

Compared to the previous example, a fraction of deeply stagnant C ₁₉ dialcohols with a pour point of -3 ° C could already be obtained from the 1st filtrate, while no high stubborn proportions were found in the fractions.

30 Example 4

200 g of Qg dialcohol mixture with a hydroxyl number of 355 (calculated from this content of C ₁₈ monoalcohol = about 10%) were dissolved in 800 ml of hot toluene as in the previous examples and then the bare solution was cooled and stirred at + 5 ° C for 3 hours . The solid portion that formed was filtered off with suction and redissolved in 468 ml of hot toluene. After cooling to room temperature (18 to 22 ⁰ C), a solid portion of 25 g ~ 12.5% was recovered from the insert with a melting range of 91-98 ⁰ C and a hydroxyl number of 368. The toluene solutions were worked up as follows: The solution cooled to + 5 ° C. was distilled and gave the fractions

lot
in g OH-
number EP
⁰ C Mixture of C ₁₉ -Di-
alcohols and C ₁₈ -
Mono alcohol 1 22nd 314 + 5 Cjg dialcohols 2
Back
was standing 116
9 357 + 2

55

The second toluene solution, which had only cooled to room temperature, was put back into operation used. It contains only about 4.5% non-toluene components with a hydroxyl number of 333 and one Freezing point of + 17 ° C.

65 Example 5

The procedure of Example 6 was changed so that in the first stage at -5 ° C (instead of iso-heptadecanedimethylol diacetate (C ₂₃ H ₄₄ O ₄ )

iso-n-heptadecanedimethylol diacetate (C ₂₃ H ₄₄ O ₄ )

Sdp.

⁰ C

155 / 0.02 torr 155 / 0.02 torr

Claims (6)

Patent claims: 1. A process for separating a mixture of dihydric alcohols having 19 carbon atoms, which has been obtained by oxo synthesis and subsequent hydrogenation from unsaturated C ₁₈ monocarboxylic acids, into high-stock and low-stock isomers by treatment with selective solvents and fractional crystallization, characterized in that the mixture of dialcohols is dissolved in the heat with solvents preferably consisting of aromatics, the high-build-up fractions are separated out by vigorous cooling, the precipitated product, which still contains low-build-up fractions, is dissolved again in the heat and cooled to a temperature higher than the first cooling temperature, after which the tall solid parts are isolated. 2. The method according to claim 1, characterized in that the first cooling to a temperature between -5 and +5 ⁰ C and the second cooling to a temperature between 15 and 25 ⁰ C takes place. 3. The method according to claim 1 and 2, characterized in that the solvent is toluene is used. 4. The method according to claim 1 to 3, characterized in that the low-stock isomers are obtained by distilling off the solvent from the first extraction stage, the accompanying C ₁₈ monoalcohol being suitably separated from the low-stock isomers by subsequent fractionation. 5. The method according to claim 1 to 4, characterized in that the distilled solvent is partly reused in the second and partly in the first extraction stage. 6. The method according to claim 1, characterized in that it is carried out continuously, 7 8 by making the solvent cycle so, is returned, while at the bottom of the that after the crystallization of the high column the low-stock dialcohols remain. stagnant C ₁₉ dialcohol remaining mother solution is fed to a separating column, for publications under consideration: which removed the solvent overhead and 5 German Auslegeschrift No. 1 010 062; again in the first and second solution processes U.S. Patents Nos. 2,234,916, 2,534,210. 409 659M26 8.64 © Bundesdruckerei Berlin