DE2107249A1 - Process for the catalytic esterification of 3,5-dicarboxybenzenesulfonates of alkaline metals with ethylene glycol - Google Patents

Description

PATENT ADVOCATE

February 15, 1971 Application file: 75,301

PATENT APPLICATION Applicant CeskoslovenskS Ökademie ved., Praha 1, Narodni tr. 3

"Process for the catalytic esterification of 3,5-dicarboxybenzenesulfonates of alkaline metals with ethylene glycol"

The invention relates to a method for catalytic esterification of 3,5-dicarboxybenzenesulfonates of alkaline metals with ethylene glycol.

German Offenlegungsschrift No. 1 952 735 describes a process for the preparation of bis / 2-hydroxyethyl / esters of 3,5-dicarboxybenzenesulfonates of alkaline metals, the subject of which is based on the direct esterification of the sulfonates mentioned with ethylene glycol. The process takes place at a mutual molar ratio of Is3 to 1:12, at elevated temperatures and in the absence or presence of zinc, tin, titanium, antimony or germanium compounds as esterification catalysts. The description of this invention shows that the corresponding bis - / - 2-hydroxyethyl / esters can be obtained in yields of 80-90% by crystallization of the esterification product after reaction times between 5 hours 20 minutes up to 2 hours 15 minutes.

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For the further processing of the esterification product from the reaction a 3,5-dicarboxybenzenesulfonate of an alkaline metal with Ethylene glycol and for direct application of this product, d. H. of the bis / 2-hydroxyethyl / ester of 3,5-dikarboxybenzenesulfonate of an alkaline metal as a monomer - if possible without further Purification of the starting sulfonate - however, it is advisable to achieve the highest possible conversion of the 3,5-dicarboxysulfonate during the esterification process and thereby to achieve the highest possible yield of his bis / 2-hydroxyethyl / ester.

" R

As is well known, the esterification of carboxy acids is made with. Ethylene glycol is always accompanied to a greater or lesser extent by the formation of diethylene glycol, which has a negative effect on the quality of the monomer and the resulting polycondensation products.

Achieving the highest possible conversion of 3,5-dicarboxybenzenesulfonate of an alkaline metal in the esterification with ethylene glycol combined with the lowest possible formation of diethylene glycol thus represents a desirable improvement in the Manufacturing process for this bis / 2-hydroxyethyl / ester.

In addition to the above-mentioned published application, it was determined that that if 3,5-dicarboxybenzenesulfonate is an alkaline Metal with ethylene glycol at a molar ratio of 1:20 to 1: 4O in a stream of inert gas at temperatures of 170-197 ° C. and in the presence of compounds soluble in the reaction mixture, e.g. B. of zinc, calcium, manganese or cobalt as esterification catalysts,

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together with inorganic or organic bases either in pure state or as an azeotropic mixture with water boiling up to 150 C and their dissociation constant in the order of magnitude

-3-8

from 10 to 10, are esterified ^ then the brs- / 2-hydroxyethyl / esters of the 3,5-dicarboxybenzenesulfonates of the alkaline metals used are obtained completely free of the starting substances used / the 3,5-dicarboxybenzenesulfonates of the alkaline metals) and with basically lower content of ester-bound diethylene glycol than in the case of the esterification, which was carried out in the absence of the aforementioned inorganic or organic bases, the resulting bis - / 2-hydroxyethyl / ester of 3,5-dicarboxybenzenesulfonate of an alkaline metal can then from the Reaction mixture can be isolated by simply distilling off the excess ethylene glycol and the volatile inorganic or organic bases; the product is then, without any further purification, Z ₀ B. polycondensation with other monomers usable.

However, the other can described in the aforementioned Laid-Open Publication as esterification catalysts may be used in the reaction medium-soluble metal compounds ₀

For the purposes of the present invention, z. B _{0 the} following bases are used! Triethylamine with a dissociation

-4 ο

constant of 5.65.10 and with a boiling point of 89.4 C in pure State and of 75.8 C as an azeotropic mixture with water, without

-5 tri-n-butylamine with a dissociation constant of 8.51.10 and with a boiling point as an azeotropic mixture with water of 99.8 ° C

-8 or beta-picoline with a dissociation constant of 1.00.10 and a boiling point of 143.4 C ₀ proved to be a suitable base

1 0 9 0 - ·; / 1 8 3 1

-5 also ammonia, with a dissociation constant of 1.79.10, Its boiling point is already -33.4 C, but that in the given Reaction mixture due to the acidity of the 3,5-dicarboxybenzenesulfonate temporarily, is bound. As the esterification of the 3,5-dicarboxybenzenesulfonate progresses, the bound base becomes gradually and after released and discharged by the inert gas. If the base forms an azeotropic mixture with water, the water formed by the esterification is also removed from the reaction mixture, which expediently contributes to the acceleration of the reaction. The base released from the reaction system, such as. B. triethylamine, the tri-n-butylamine, or the beta-picoline, can be found in a simpler way ^ Collected in a manner and without substantial purification for further reactions to be used. As the most significant effect by which the aforementioned basic compounds are involved in the esterification of S, 5-dicarboxybenzenesulfonates claim, however, is the up to 14-fold reduction in the content of the first bound diethylene glycol and the up to a 7-fold reduction in the total conversion of ethylene glycol in diethylene glycol.

In order to keep the discoloration of the reaction mixture small, it is advantageous to the esterification in the presence of inhibitors of Äthylenfe glycoloxydation - such. B. of salts of hypophosphorous acid,

z. B. of sodium hypophosphite monohydrate - to perform. One uses in this case concentrations of 0.03-0.5% by weight, based on the 3,5-dicarboxybenzenesulfonate.

The invention relates to a process for the esterification of 3,5-dicarboxybenzenesulfonates alkaline metals of the general formula

1 0 9 e ■■■ -) / 1 8 3 1

3,5-C Hg (COpH) ₉ SO-Mj in which M denotes a sodium or potassium atom, with ethylene glycol in the presence of metal esterification catalysts, and it consists in that the aforementioned 3,5-dicarboxybenzenesulfonate with ethylene glycol in a molar ratio of 1 : 20 to 1:40 and mixed with 0.1 to 1.0 wt .- ^ zinc, calcium, manganese or cobalt oxide or acetate as esterification catalysts and in an inert gas stream - optionally with the addition of inhibitors of ethylene glycol oxidation - until the disappearance of free carboxyl groups is heated at 170 - 197 C, with still in the reaction mixture

-1 -3
2.3 * 10 to 6.5.10 mol of inorganic or organic bases per 1 mol of the 3, 5-DikarboxyE> enzolsulfonat are present, which boil up to 150 C either in the pure state or in the form of an aqueous acetate and their dissociation constants in the order of magnitude from 10 to 10, after which the bis - / 2-hydroxyethyl / ester of 3,5-dicarboxybenzenesulfonate of an alkaline metal formed by the reaction is isolated by distilling off the excess ethylene glycol and the aforementioned inorganic or organic base.

The examples given below illustrate the invention Esterification process of 3,5-dicarboxybenzenesulfonates more alkaline Metals with ethylene glycol, without limiting or restricting them.

example 1

In a 500 cm glass flask, which is fitted with a stirrer with a mercury seal, a thermometer, a 30 cm long reflux condenser with ethylene glycol tempered to 40 - n0 ° C in the condenser jacket and one

10 9839/183 1

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Nitrogen supply / oxygen content less than 5 ppm), 35 g (0.1305 mol) of sodium 3 ₇ 5-dicarboxybenzenesulfonate, 162.0 g (2.6100 mol) of ethylene glycol (diethylene glycol content 0.2% by weight ) t 0.175 g (0.50 wt .- # based on the 3,5-Dikarboxybenzolsulfonat) zinc oxide and 0.830 g of tri-n-butylamine, introduced (3,43.10 ~ ² mol / mol 3,5-Dikarboxybenzolsulfonat). The flask was then flushed out with nitrogen and immersed in a thermostat preheated to 210 ° C. After switching on the stirrer, the nitrogen flow was set to 2 l / h. The temperature of the glycol circulating in the cooler jacket was initially maintained at 40 ° C. The temperature of the reaction mixture rose to 175 ° C. within 10 minutes. After 2 hours, the temperature in the condenser was increased to 110 ° C. and the temperature of the reaction mixture was increased to 197 ° C. over the course of 30 minutes. The water formed by the reaction and escaping through the reflux condenser together with the tri-n-butylamine was collected before the condenser was sealed off from the atmosphere. After a further 45 minutes, the concentration of the 3,5-dicarboxybenzenesulphonate fell to zero, the nitrogen flow was increased to 10-15 l / h and the reaction ended after a further 20 minutes. The excess ethylene glycol, which according to the analysis contains 0.41 wt .- # diethylene glycol, was removed from the completely crystal-clear reaction mixture in vacuo (13 torr). According to the analysis, the distillation residue (46 g) no longer contained any free carboxyl groups; After converting the analysis results to the theoretically expected amount of bis / 2-hydroxyethyl / ester of sodium 3,5-dicarboxybenzenesulfonate, the ester-bound diethylene glycol content is 0.86% by weight . The total conversion of ethylene glycol to diethylene glycol that occurred in the course of the esterification was accordingly 0.77% by weight .

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In a parallel experiment carried out at 197 C with the same concentrations of the starting material (molar ratio of 3,5-dicarboxybenzenesulfonate to ethylene glycol 1:20) and with the same concentration of ZnO as catalyst, but in the absence of the amine, practically the theoretical yield of carboxyl-free was again obtained bis - ^ - HydroxyathyV-ester, the excess ethylene glycol distilled off from the reaction mixture after the reaction, however, contained 0.74 wt Diethylene glycol of 2.17 % during esterification.

Example 2

In the reactor described in Example 1, 50 g (0.1864 mol) of sodium 3,5-dicarboxybenzenesulfonate, 347.15 g (5.593 mol) of ethylene glycol (diethylene glycol content 0.2% by weight ), 0.25 g (0 , 5 wt .- # on the 3,5-dicarboxybenzenesulfonate) zinc oxide and 6.67 g (3.53.10 mol / mol of 3,5-dicarboxybenzenesulfonate) triethylamine introduced. The temperature in the cooler jacket was initially set to 40 ° C. The temperature of the reaction mixture rose to 185 ° C. within 15 minutes. After 2 hours, the temperature in the cooler jacket was increased to 110 and the temperature of the reaction mixture to 196.degree. The water escaping from the reaction mixture together with the triethylamine via the reflux condenser was collected before the condenser was sealed off from the atmosphere. After 1 hour, the concentration of the 3,5-dicarboxybenzenesulfonate fell to zero, the nitrogen flow was increased to 10-15 l / h and the reaction ended after a further 30 minutes. The reaction mixture was processed in

1 0 9 Γ:: - ■ / 1 8 3 1

- ο -

as described in example 1. The excess ethylene glycol distilled off from the reaction mixture contains, according to the analysis, 0.15 wt .-jS ester-bound diethylene glycol, which corresponds to a total conversion of ethylene glycol to diethylene glycol of 0.30 % during the esterification.

In an experiment conducted at 197 C parallel experiment at the same concentrations of the starting materials (molar ratio 1 s30) and in the presence of 0.75 wt -.% Zinc oxide, but in the absence of Triäthylamins, you won Although practically the theoretical yield of karboxylfreiem bis- / 2- Hydroxyethyl / ester, the excess ethylene glycol distilled off from the reaction mixture after the esterification, however, contained 0.50 wt.% Of free diethylene glycol and the ester 3.18 wt Diethylene glycol of 1.08 % during esterification.

Example 3

In the reactor described in Example 1, 40 g (0.1492 mol) of sodium 3,5-dicarboxybenzenesulfonate, 370.31 g (5.9660 mol) of ethylene glycol (diethylene glycol content 0.2% by weight ), 0.30 g (0.75 g) zinc oxide

-3 and 0.10 g of triethylamine (6.6.10 mol / mol of 3,5-dicarboxybenzenesulfonate) brought in. The temperature in the reflux cooler was initially set to 110 C, the temperature of the reaction mixture * rose gradually from the initial value 190 C up to 197 C. The other reaction conditions were the same as those given in Example 2. After 3.5 The concentration of 3,5-dicarboxybenzenesulfonate decreased for hours

-P-

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Zero value from and after a further 45 minutes, in which the nitrogen flow was increased to 10-15 l / h, the reaction was ended. According to the analysis, the excess ethylene glycol distilled off from the reaction mixture contains 0.36 wt. Diethylene glycol and the distillation residue, the bis - / 2-hydroxyethyl / ester of sodium 3,5-dikarboxybenzolsulfonats, then 1.07 wt -.% Estergebundenen Diäthylenglykols, representing a total conversion of ethylene glycol to diethylene glycol of 0.31% during the esterification is equivalent to.

Example 4

The experiment described in Example 3 was treated with the same concentrations of the starting materials (molar ratio 1:40), and the same proportion of the same catalyst, but at a temperature of 185-197 ⁰ C and in the presence of 0.2 g (1,32JO " ² mol / mol 3,5-dicarboxybenzenesulfonate) triethylamine repeated The bis - / 2-hydroxyethyl / ester is again obtained in practically theoretical yield, the excess ethylene glycol distilled off from the reaction mixture after the esterification is complete contains 0.26 wt. Diethylene glycol, the isolated bis / 2-hydroxyethyl / ester then 0.86% by weight of ester-bound diethylene glycol, which corresponds to a total conversion of ethylene glycol to diethylene glycol of 0.18 % during the esterification.

In a parallel test carried out at 197 C with the same concentrations of the starting materials as above and with 0.28 g (0.70 Wt .- ^) zinc oxide and 0.012 g (0.03 wt .-%) calcium acetate as esterification catalysts, but in the absence of triethylamine, won one after 1.75 hours practically the theoretical yield of

- 10 -

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bis - ^ - HydroxyäthylZ-ester, the excess ethylene glycol distilled off from the reaction mixture after the esterification, however, contained 0.43 wt .- # diethylene glycol and the ester 2.45 Gevi, -% ester-bound diethylene glycol, which corresponds to a total conversion of ethylene glycol to diethylene glycol of 0 , Corresponds to 65% during the esterification.

Example 5

In an experiment carried out according to Example 3 with the same concentration of the starting materials and the zinc oxide as a catalyst, but at 195-197 ° C and in the presence of 0.2 g (1.44.10 " ² mol / mol 3,5-dicarboxybenzenesulfonate) beta picoline proceeded, it practically won after 2.25 hours, the theoretical yield of the bis- / 2-hydroxyethyl / ester of sodium 3,5-dikarboxybenzolsulfonats ₀ the distilled after the esterification from the reaction mixture Excess ethylene glycol containing 0.42 wt. -% diethylene glycol and the ester 0.84 wt .- /? Ester-bound diethylene glycol, which corresponds to a total conversion of ethylene glycol to diethylene glycol of 0.38 % during the esterification.

In a parallel experiment carried out at 197 ° C. and according to Example 3 with the same concentrations of the starting materials and the zinc oxide as catalyst, but in the absence of beta-picoline, the theoretical yield of the bis / 2-hydroxyethyl / ester of sodium was also obtained -3,5-dikarboxybenzolsulfonats, but the distilled after the esterification from the reaction mixture Excess ethylene glycol containing 0.47 wt -.% Diäthylengiykols and the ester 3.19 wt .- ^ estergebundenen Diäthylenglykols, representing a total conversion of ethylene glycol to diethylene glycol was 0, 69 % during the esterification.

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Example 6

In the reactor described in Example 1, 60 g (0.2237 mol) of sodium 3 _/ 5-dicarboxybenzenesulfonate, 347.16 g (5.5931 mol) of ethylene glycol (diethylene glycol content 0.2% by weight), 0.3360 g (0.56% by weight)

Manganese tetraacetate and 0.0600 g (0.10% by weight) cobalt tetraacetate as

" -1

Esterification catalysts are weighed in and 3.00 g (2.35.10 mol ammonia / mol 3,5-dicarboxybenzenesulfonate) ammonium carbonate monohydrate and 0.02 g sodium hypophosphite monohydrate added as an inhibitor of ethylene glycol oxidation. The reaction mixture is heated to 197 ° C. and left at this temperature for 3 hours, after which the reaction mixture already contained no free carboxyl groups. The remainder of the ammonia was removed from the reaction mixture by a nitrogen stream of 10-15 l / h and the excess ethylene glycol was distilled off under reduced pressure. According to the analysis, the distillation product contains 0.23 wt. % ester-bound diethylene glycol, which corresponds to a total conversion of ethylene glycol to diethylene glycol of 0.42 % during the esterification.

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Claims (1)

- 12 PATENT CLAIMS: .1. Process for the esterification of 3,5-dicarboxybenzenesulfonates of alkaline metals of the general formula 3,5-C ₆ H ₃ (CO ₂ H) ₂ SO ₃ M ₇ in which M denotes a sodium or potassium atom, with ethylene glycol in the presence of metal esterification catalysts, characterized in that the aforementioned 3,5-dicarboxybenzenesulfonate with ethylene glycol in a molar ratio of 1:20 to 1:40 and with 0.1 to 1.0 wt .-% zinc, calcium, manganese or cobalt oxide or -Acetates mixed as esterification catalysts and mixed in a stream of inert gas with the addition of inhibitors of ethylene glycol oxidation until free carboxyl groups disappear at 170 - 197 C is heated, with 2.3.10 to in the reaction mixture -3 6.5.10 moles of inorganic or organic bases from 1 mole of des 3,5-dikarboxybenzenesulfonate used are present, either in the pure state or in the form of an aqueous acetone up to 150 C boil and their dissociation constants in the order of magnitude from TO "to 10", after which the one formed by the reaction "bis - / 2 ~ hydroxyethyl / ester of 3,5-dikarboxybenzenesulfonate one alkaline metal by distilling off the excess ethylene glycol and the aforementioned inorganic or organic bases is isolated. 2. The method according to claim 1, characterized in that that as inorganic or organic bases trialkalamine, z. B. triethylamine, tri-n-butylamine ^ also pyridine bases, z. B. Beta picoline, or ammonia can be used. - 13 - 10 9 8 3 9/1831 3. The method according to claim 1 and 2, characterized in that g <e characterizing. net that the esterification in the presence of inhibitors of Ethylenglykoioxydation, z. B ₀ of 0.03-0.5% by weight of salts of hypophosphorous acid, for example of sodium hypophosphite monohydrate, is carried out. 10 9 8 3 9/1831