DE1273521B - Process for the continuous production of esters used as plasticizers - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY GERMAN 4MTW ^ PATENT OFFICE Int. Cl .:

C07c

EDITORIAL

BOIj C08f German KL: 12ο-14 ^ / δ & 12g-11139b-22/06; gjjj 39c-25/01 ^ a Number: 1,273,521 File number: P 12 73 521.6-42 (P 38889) Registration date: March 2, 1966 Display day: July 25, 1968

Dicarboxylic acid esters of primary alcohols serve as plasticizers in plasticizable high polymers, especially when processing polyvinyl chloride.

Due to their good compatibility and excellent effect, they are used when processing Polyvinyl chloride, especially phthalic acid esters of primary alcohols, the alkyl group of which has 8 to 10 carbon atoms contains, application.

These esters are usually prepared by esterifying the corresponding alcohols with phthalic anhydride in the presence of acidic catalysts, such as sulfuric acid or toluenesulfonic acid. However, it is known that these acidic catalysts can be replaced by compounds of titanium or zirconium which contain one or more alkoxide groups in addition to hydroxyl groups and optionally halogen groups and which are also supported on inert supports, such as. B. activated carbon, applied, can be applied. It is also known to use Ti (OH) ₄ as an esterification catalyst. The use of the compounds mentioned has the advantage over the use of acidic catalysts, such as sulfuric acid or toluenesulphonic acid, that if sufficiently large amounts of catalyst are used, the esterification can be carried out to the end until the phthalic acid has been completely converted, with a final acid number of 0 during the main esterification. 3 to 0.4 and after the excess alcohol has been distilled off under a pressure of up to 3 Torr towards the end an acid number of 0.1 is reached and the catalyst can be separated off by filtration at the end of the reaction after the addition of filter aids, so that no alkali washing is necessary, as must be done when using acidic catalysts.

In addition to the advantage of the simpler mode of operation, this method also has the particular advantage on that an absolutely ion-free ester can be obtained thereby. Such ion-free esters are in the Production of polyvinyl chloride, which is to be used as an electrical insulation material, is preferred.

The esters obtained by esterification of phthalic acid or phthalic anhydride have im generally a faint odor of its own. This smell comes from traces of contamination, the persistently remain in the ester despite the vacuum distillation at 2 to 3 torr.

Deodorization of unpleasant smelling compounds by treatment with water vapor is commonly used. This process can be carried out using acidic catalysts such as sulfuric acid or toluenesulfonic acid, easily perform. The steam distillation is after

Process for the continuous production of
esters serving as plasticizers

Applicant:

Polycarbona-Chemie G. m. B. H., 4102 Homberg

Named as inventor:

Dipl.-Ing. Dr.-Ing. Helmut Schwarzhans,

4130 Moers

the alkali wash is carried out either in the presence of the excess alcohol or after it has been distilled off. However, such esters treated in a stirred tank are not completely odorless even after steam distillation.
In the case of esterification with a catalyst consisting of titanium or zirconium oxides deposited on activated carbon, difficulties arise during deodorization with steam, since the residual esterification of the last traces of phthalic acid takes place only in the presence of the catalyst when the alcohol is distilled off.

If the steam treatment is carried out in the presence of the catalyst, a catalytic one occurs accelerated saponification of the ester, which is noticeable in a renewed increase in the acid number power.

The catalyst must therefore in the processes which have become known up to now before the steam treatment filtered off or inactivated by adding an inhibitor.

If an inhibitor is used, the catalyst becomes unusable for repeated use and must be discarded. The separation by filtration requires the use of filter aids, because the oxides applied to activated carbon remain very finely distributed in the ester in suspension and do not move drop. However, a catalyst diluted with filter aid is for use in others Esterifications can no longer be used and must therefore also be discarded.

It has now been found that these difficulties in the continuous production of as Esters serving plasticizers by esterification of

809 587/593

3 4

primary alcohols with dicarboxylic acids in counter-hexanol (30% excess compared to the theoretical

wait of consumption applied to inert carrier material) in the presence of 30 kg of a zirconium

Oxides of the elements of group IV of the periodic catalyst (for preparation see end of examples) in

System with an ordinal number S: 22 thereby remedying the usual way implemented. After 11 hours it was can that after the practical completion of 5, the acid number 0.35. Well, gradually became one

Esterification the main amount of excess up to 3 Torr improving negative pressure of the

Alcohol is distilled off, then most of the excess alcohol is distilled off. After 5 hours it was

Catalyst at 80 to 200 ⁰ C, preferably with the acid number 0.07 and the OH number 0.6. Now was

about 120 ° C is separated from the ester and the catalysis returns ¹ J ₂ hours over three nozzles of water vapor through the sator in the esterification process, is now blown io esters, wherein the pressure at 12 Torr back

the ester passed in a known manner by treatment with and the temperature was 194 ^° C. After this

Steam deodorized and finally the rest of the treatment, the acid number was 0.16 and the OH

separates union excess alcohol. Number 0.34. The smell of the ester was barely there

The catalysts used are those which are perceptible on inert.

Support material applied oxides of titanium or 15 BeisoieI2
Zircon.

The catalyst is separated off at 80 to When the same approach as in Example 1 was used

200 ⁰ C, preferably at about 120 ° C, for example in the amount of catalyst increased to 150 kg. To

a separator. A complete separation of the 7 hours resulted in an acid number of 0.29, see above

Catalyst, e.g. B. when using a separator, 20 that could be switched to alcohol distillation,

can not be reached. Mostly about 95% of the. After 5 hours the acid number was 0.06 and the

The catalyst used was separated off, the 0.8 without further OH number. After V ₂ hours of treatment with

Reconditioning are ready for use again. Water vapor at 190 ° C and 13 Torr was the

Completely surprising and for the person skilled in the art, the acid number is not 0.25 and the OH number is 0.4. The ester odor predictably upset the rest of the ester 25 was extremely faint,
5% of the catalyst no longer remained in the steam treatment, so that there is no need for further use
Soap reaction occurs.

This surprising fact is only possible with the same approach as in example 2

the continuous implementation of the process and obtained an acid number of 0.32 after 7 hours. the

the simple recovery of the bulk of the bulk of the excess alcohol was made

Catalyst, since the ester after the distillation of the then gradually increased to 40 Torr

Most of the excess alcohol still improves negative pressure within IV ₂ hours

has an acid number of 0.15 to 0.2, which now distills off at the, after which the acid number was 0.12. That

Steam treatment is lowered to 0.1. 35 plasticizers still containing about 2% alcohol

The separation of the catalyst at the end of the mixture was cooled to about 120 ° C and then

Esterification, d. H. before distilling off the fed in a separator. The catalyst content

Excess alcohol used, is not possible, was 1.29% when passing through the separator

since the active substance of the catalyst partially decreased in the 0.07% (i.e. by 94.6%) · The catalyst

used alcohols to form 40 was returned to the reaction kettle and the

is soluble in alcoholates. Loss by adding an appropriate amount

After the main amount of fresh catalyst has been distilled off, it is balanced. The plasticizer

Alcohol disturbs the remaining amount of alcohol after heating to 194 ° C on the head

(about 2% of the total mass of the mixture) given a stripping column, which from below with

Catalyst separation surprisingly not applied steam and at a pressure of

more. After complete separation of the excess 40 Torr was operated. The one flowing down below

Alcohol would because of the higher viscosity and the plasticizer ester was odorless, anhydrous and

higher specific gravity the catalyst separation again had an OH number of <0.05. It was after

be made more difficult. Addition of 0.1% activated carbon as a filter aid

So while the catalyst is filtered out of the full 50. Of the distillation of the excess

Esters contained in excess alcohol because of the alcohol solution and the stripping column

possibility of the active substance as well as from the full distillate, the water was separated and the

finished esters due to the deficient alcoholic layer return to the esterification process.

Sedimentation speed out with simple means.

cannot be separated satisfactorily, he leaves 55 _Ώ _, · _ _ ·. t _A
in this state of about only 2%

At least about 95% of the ester contained in alcohol.

at a temperature of about 120 ° C in the simpler 1.75 t of 8 t of 2-ethylhexanol as recycled alcohol

Separate way. distilling off and from the stripping column.

The process according to the invention therefore allows 60 142 kg of the 150 kg amount of catalyst used

an ion-free, absolutely alcohol-free and odor- consisted of that recovered in the separator

loose carboxylic acid ester after a simplified catalyst. After 7 hours the acid number was 0.30.

Procedure with constant reuse of the Kata- The approach was then, as explained in Example 3,

lysators to manufacture. further processed with the same results.

. 65 The catalyst used was prepared as follows

Example ^{X has} been:

In a stirred tank of 17 m ³ capacity In a thin liquid slurry of 18.9 kg

3.51 phthalic anhydride with 8 t 2-ethyl powdered activated charcoal in distilled water

4 kg of zirconium tetrachloride are gradually introduced with stirring. For this, see further Stir until pH 7, slowly adding 10% ammonia. Then it is filtered and so long with hot washed with distilled water until the filtrate is free of chlorine. The moist, essentially solid filter cake is used as a catalyst. If he becomes dry, he will lose his activity.

In addition to 2-ethylhexanol, this process has so far used: isooctyl, isononyl and isodecyl alcohol or a mixture of straight-chain alcohols with carbon numbers from 6 to 10 or 8 to 10 (which is produced according to the process of German patent specification 1 014 088 and under the protected name »Alfol« is in the trade). In addition to phthalic anhydride, maleic and trimellitic anhydrides were used used. In all cases the procedure was found to be beneficial, and it was get appropriate results.

Claims (1)

Claim: 1. A process for the continuous production of esters serving as plasticizers by esterification of primary alcohols with dicarboxylic acids in the presence of oxides of the elements of the fourth group of the periodic system with an atomic number ^ 22, which are applied to an inert carrier material, characterized in that after the practical completion the esterification distilled off the main amount of excess alcohol, then separates most of the catalyst at 80 to 200 ⁰ C, preferably at about 120 ⁰ C, from the ester and recirculates the catalyst to the esterification process, now the ester in a known manner by treatment with steam deodorized and finally separates off the remaining excess alcohol.