DE3008174A1 - Alkylene glycol ether carboxylic ester prodn. - using organo-zirconium cpd. as catalyst and opt. co:catalyst, useful as solvent and plasticiser - Google Patents

Abstract

In the prodn. of carboxylic esters (I) of alkylene glycol ethers by reacting alkylene oxides (II) with carboxylic esters (III), the catalyst used contains organo-Zr cpd(s). (IV) of the formula Zr-(R)n (in which n is the valency of Zr and the R substits. independently are 1-4C (ox)alkyl, (ox)aryl, alkaryl with 1-4C alkyl gp(s)., aralkyl with a 1-4C alkylene gp. or a halogen atom but max. 3 halogen atoms are bound to the Zr atom). A cocatalyst (V) may also be used, i.e. a 12C N-alkyl-carbonamide, N-1-4C alkyl-pyrrolidone, benzotriazole or amine of the formula N(R')3 (in which R' is H or a 1-18C hydrocarbyl gp.; 2 R' substits. can form a cyclic hydrocarbyl gp.). Pref. (II) is ethylene oxide (EO) or propylene oxide and (III) has the formula R2-CO-OR3 (in which R2 is H or 1-4C alkyl. R3 is 1-4C alkyl). In (IV), n is 4, the R gps. are the same and are 1-3C (ox)alkyl, (ox)phenyl or benzyl and (V) is a prim., sec. or tert. 1-4C alkylamine. The amt. of (IV) used is 0.05-10 mole-% w.r.t. (II), whilst the (IV)/(V) molar ratio is 0.01-10. The (II)/(III) molar ratio is 1:1-50, reaction temp. 100-250 deg.C and conversion 1-60 wt.%. It is pref. to react EO and ethyl acetate (IIIA) in 1:3-30 molar ratio in the presence of 0.1-5 (0.5-3) mole-% (IV) w.r.t. EO and a (IV)/(V) molar ratio of 0.1-4 at 130-180 deg. C to a conversion of 5-45 (10-25) wt.%. Large amts. of monoadduct (monoalkylene glycol alkyl ether ester) can be obtd. and the conversion is relatively high. (I) are valuable solvents for paints, lacquers, adhesives or printing inks and can also be used as plasticisers.

Description

Process for the preparation of carboxylic acid esters

of alkylene glycol ethers The invention relates to a process for the preparation of carboxylic acid esters of alkylene glycol ethers by reacting alkylene oxides with Carboxylic acid esters in the presence of catalysts, preferably monoalkylene glycol ether esters can be obtained.

From the Belgian patent 660 601 it is known to use esters (carboxylic acid glycerides) with alkylene oxides in the presence of catalysts soluble in the glycerides, for example Boron trifluoride to convert to ether esters.

Furthermore, in the German Offenlegungsschrift 24 54 616 there is a method for the production of carboxylic acid esters of alkylene glycol ethers by reacting Described alkylene oxides with carboxylic acid esters in the presence of catalysts, where as catalysts halides or organometallic compounds of zinc, Aluminum, titanium, tin or iron and optionally cocatalysts, consisting from a nitrogen, phosphorus, antimony, arsenic or bismuth compound, the at least 1 halogen or carbon atom directly to the nitrogen, phosphorus, antimony, Contains arsenic or bismuth atom bound, are used.

This known process for the preparation of carboxylic acid esters of Alkylene glycol ethers have the particular disadvantage that the amount of monoalkylene glycol alkyl ether esters (Monoadducts), which should form preferentially as desired, leave something to be desired leaves. It on the other hand, relatively large amounts of tends to form undesired di-, tri- and even higher alkylene glycol alkyl ether esters (di-, tri- and polyadducts).

It has now been found, surprisingly, that these disadvantages are remedied can be and that in particular a large amount of monoadducts, at the same time also a relatively high conversion of the starting components can be obtained if the alkylene oxides are used and carboxylic acid esters in the presence of certain organozirconium compounds as catalysts implemented, with suitable cocatalysts also optionally being present.

Accordingly, the process according to the invention for the preparation of carboxylic acid esters of alkylene glycol ethers by reacting alkylene oxides with carboxylic acid esters in The presence of catalysts, characterized in that the implementation of the Alkylene oxides and carboxylic acid esters carried out in the presence of a catalyst consisting from at least one organozirconium compound of the general formula I Zr- (R) n wherein n is the valence of zirconium and the substituents R are identical or different can be an alkyl radical or oxalkyl radical with 1 to 4 carbon atoms, aryl radical or Oxaryl radical, alkaryl radical with one or more alkyl groups, each with 1 to 4 C atoms, aralkyl radical with an alkylene group with 1 to 4 C atoms, or a halogen atom mean, with the proviso that a maximum of 3 halogen atoms are bonded to the zirconium atom, and optionally a cocatalyst consisting of at least a nitrogen compound from the group of the N-alkyl-carboxamides with a total of 12 carbon atoms, N-alkyl-pyrrolidones with 1 to 4 carbon atoms in the alkyl group, benzotriazoles and the compounds of the general formula II N (R1) 3 II in which R1 is hydrogen or denotes a hydrocarbon radical with 1 to 18 carbon atoms, two substituents R1 can also form a cyclic hydrocarbon radical.

In the process according to the invention, the type of alkylene oxides and carboxylic acid esters which are used is not critical. A wide variety of alkylene oxides, expediently those having 2 to 6 carbon atoms, and carboxylic acid esters can therefore be used. Ethylene oxide and propylene oxide or carboxylic acid esters of the formula III are preferred where R2 is hydrogen or an alkyl group with 1 to 4 carbon atoms, preferably hydrogen, CH3 or C2H5, and R3 is an alkyl group with 1 to 4 carbon atoms, preferably CH3 or C2H5.

Ethylene oxide or methyl acetate or is particularly preferred Ethyl acetate.

The reaction equation on which the process according to the invention is based is shown below, for example, with ethylene oxide as alkylene oxide and ethyl acetate as carboxylic acid ester (x = number of ethylene oxide units): (In the case of x = 1, the compound formed is called monoethylene glycol ethyl ether ester of acetic acid).

The ratio (molar ratio) of the amounts of alkylene oxide and Carboxylic acid ester can be varied within wide limits. With a relatively high amount a large number of moles of (x) alkylene oxide are added to the carboxylic acid ester of alkylene oxide. In contrast, with a relatively small amount of alkylene oxide, a small amount is added Moles. In this case, the monoadduct is predominantly obtained because the Selectivity of the organozirconium compounds to be used according to the invention for addition only one alkylene oxide unit is particularly pronounced.

In the process according to the invention, the molar ratio of alkylene oxide is to carboxylic acid ester in general at 1: 1 to 1:50, preferably at 1: 3 until 1:30.

According to the invention, organozirconium compounds are used as the catalyst (base catalyst) of formula I used. The substituents R on the zirconium atom can be identical or different be, with the proviso that in the case of halogen as a substituent, the number of halogen atoms is no more than three.

The alkyl and oxalkyl radicals can be straight-chain or branched. Of the Aryl and oxaryl radicals can carry substituents, for example one or more Halogen atoms. The aryl and oxaryl substituents are preferably phenyl (CcHS-), respectively Oxphenyl (CsHsO-). The alkaryl radical is preferably tolyl or ethylphenyl. Of the The aralkyl radical is preferably benzyl or phenylethyl. Halogen as a substituent on Zirconium atom is preferably chlorine.

The value of n in formula I is preferably 2, 3 or 4, in particular 4th

According to the invention, preferred basic catalysts are such organozirconium compounds of formula I, in which n = 4 and the substituents R are the same and an alkyl or oxalkyl group with 1 to 3 carbon atoms, for example CH3-, C2H5-, C2H5O-, n-C3HXO- and iso-C3HzO, phenyl or oxphenyl group, or a benzyl group.

Although with the basic catalysts alone the implementation of Alkylene oxide and carboxylic acid ester leads to high yields of the desired monoadduct, it has proven to be particularly useful to shorten the response time, also use cocatalysts.

Preferred cocatalysts according to the invention are compounds of Formula II, in which the substituents R1, which can be identical or different, Hydrogen, an alkyl group which can be straight-chain or branched, with 1 to 4 carbon atoms or a cycloalkyl group with 5 to 6 carbon atoms, with the proviso, that not all three R1 are hydrogen.

Primary, secondary and tertiary C1 to C4 alkylamines are particularly preferred according to formula II, for example monoethylamine, monobutylamine, dimethylamine, dibutylamine, Trimethylamine and triethylamine.

The amount of catalyst (basic catalyst) can be used within wide limits vary. When using relatively small amounts of catalyst must be with a relatively long reaction time can be expected, with a relatively large amount of catalyst it can lead to a increased formation of by-products.

According to the invention, the amount of catalyst is generally 0.05 up to 10 mol%, preferably 0.1 to 5 mol%, especially at 0.5 to 3 mol%, based on the alkylene oxide used.

The amount of cocatalyst can also vary within wide limits. The upper limit is limited in particular because the There is a risk of the end product being contaminated with cocatalyst. In the event of the use of cocatalysts is the molar ratio of catalyst to cocatalyst according to the invention in general from 0.01 to 10, preferably from 0.1 to 4.

The catalyst and cocatalyst can be used as such. In the case of the catalytic converter in particular, there is also the option of using a conventional one Apply inert carrier material, such as clay, and use it in this form.

The reaction temperature in the process according to the invention is im generally 100 to 250 cc. Reaction times below 100 cc result in relatively long reaction times and above 250 OC there is already a risk of alkylene oxide decomposition.

A reaction temperature of 130 to 180 cc is preferred.

The inventive method for reacting alkylene oxides with Carboxylic acid esters can be carried out continuously or batchwise, the reaction being carried out at elevated pressure or at that corresponding to the reaction temperature Vapor pressure can go on.

A pressure of less than 50 bar is expediently, preferably from 10 to 20 bar, applied. In the case of discontinuous operation, the pressure falls as the reaction progresses and remains constant when the reaction has ended.

Since the reaction between alkylene oxide and carboxylic acid ester is exothermic runs, an apparatus is required that allows the heat of reaction to be dissipated. The reaction apparatus therefore expediently consists of a reaction vessel, preferably a stainless steel autoclave equipped with a stirring system and is equipped with a double jacket to accommodate cooling liquid.

The reaction can be carried out in such a way that the alkylene oxide, the carboxylic acid ester, for example that recovered from previous reactions, and the catalyst, optionally also cocatalyst, together at the reaction temperature be heated, or that carboxylic acid ester and catalyst, optionally also cocatalyst, submitted and heated to the reaction temperature, whereupon the alkylene oxide is added will.

The alkylene oxide can be used all at once or in proportions one after the other are added.

When preparing for the reaction and during the reaction, it becomes oxygen and water, which could destroy the catalyst, expediently kept away. Therefore, the reaction is preferably carried out in an inert atmosphere, for example carried out under nitrogen.

The degree of conversion to which the reaction is carried out can vary widely Limits vary. It has been found that the selectivity to monoadducts is very high if you keep a relatively low metabolic rate.

By definition, the metabolic rate is the number of percentages by weight from the sum of the amounts by weight of converted alkylene oxide and converted carboxylic acid ester, based on the quantities used for these two.

The turnover should therefore be achieved with a view to a high monoadduct yield can be kept relatively low. On the other hand, this results in that large Amounts of incurred unreacted carboxylic acid ester, which is too relative leads to high distillation costs.

In the process according to the invention, the metabolic rate is usually at 1 to 60% by weight, preferably at 5 to 45% by weight, in particular at 10 to 25 Wt%. In this case, all of the alkylene oxide used is preferably allowed to react, in order to avoid inexpedient further processing of unreacted alkylene oxide.

The reaction time can vary within wide limits, preferably but a reaction time is chosen in which the desired metabolic rate is reached in a relatively short time. It has been shown that for high monoaddhkt austeuten long residence times are usually unfavorable. In general, the Response time depending on the temperature and size of the quantities used 0.25 to 10 hours, preferably 1 to 5 hours.

After the reaction has ended, the catalyst, if it is in the reaction mixture is present in the solid phase (heterogeneous phase), filtered off and then the reaction mixture worked up by distillation, the desired products being obtained. You can also without prior removal of the catalyst and, if appropriate, cocatalyst distill (fractionate) and use the catalyst remaining in the bottom again.

If, on the other hand, the catalyst is dissolved in the reaction mixture (homogeneous liquid phase), it is not necessary to remove it before distillation, it remains in the distillation sump.

The process according to the invention leads to very high yields of alkylene glycol alkyl ether esters. In addition, they arise - precisely because of the surprisingly good selective effect of the organozirconium compounds used according to the invention - relatively high amounts to the particularly desired monoalkylene glycol alkyl ether esters. When using the chlorine-free basic catalysts proposed according to the invention the present method has the further advantage that it practically none Corrosion of the reaction apparatus made of metallic material, which before is to be feared especially in the presence of chlorine.

The use of these basic catalysts also results in that an absolutely chlorine-free reaction product is obtained, which is particularly desirable is.

The alkylene glycol alkyl ether esters are valuable solvents for Paints, varnishes, adhesives or printing inks. In addition, they are for example also used as a plasticizer.

The invention will now be explained in more detail by means of examples.

Example 1 In a 2 l steel autoclave with a magnetic stirrer, 1320 g (15 Moll dry ethyl acetate, 21.6 g (0.07 mol; 2.3 mol%, based on the Ethylene oxide) zirconium propoxide, ZrOC3H7) 4, and 4 g (0.04 mol) of triethylamine and flushed three times with dry nitrogen at 15 bar.

After the (one-time) metering in of 160 ml (3 mol) of ethylene oxide over The autoclave became a nitrogen-flushed pressure lock within an hour heated to 180 ° C. with stirring and at this temperature for 2 hours with stirring left. After this time, the ethylene oxide had completely reacted. The autoclave pressure, which initially rose to 14 bar, fell to 12 bar by the end of the reaction.

The material conversion was 30% by weight.

1450 g of dark yellow, clear reaction mixture were obtained.

After the excess ethyl acetate had been separated off by distillation, this remained 430 g of crude mixture, which - after a further fractional distillation separated - as a percentage in percent by weight composed as follows: ethylene glycol monoethyl ether 1.8 dioxane <0.2 ethyl glycol acetate 74.5 ethyl diglocol acetate 17.9 ethyl triglycol acetate 1.8 higher-boiling portion and residue 3.8 (ethyl glycol acetate, ethyl diglycol acetate and ethyl triglycol acetate is the abbreviated form for mono-, di- and triethylene glycol ethyl ether esters of acetic acid).

Example 2 In the same autoclave as in Example 1, 1320 g (15 mol) dry ethyl acetate, 7.2 g (0.023 mol; 2.3 mol%, based on the amount used Ethylene oxide) zirconium propoxide, ZrOC3H7) 4, and 1.3 g (0.01 mol) of triethylamine and flushed three times with dry nitrogen at 15 bar. After (one-off) dosing of 55 ml (1 mol) of ethylene oxide was, as described in Example 1, after the same Heating time the complete ethylene oxide addition in two hours at 180 OC and 12 bar carried out.

The material conversion was 10% by weight.

The raw mixture drained from the cold autoclave was as in Example 1 described worked up by distillation. The mixture isolated had after deducting the excess ethyl acetate, the following composition in percent by weight: Ethylene glycol monoethyl ether 0.3 dioxane <0.1 ethyl glycol acetate 90.0 ethyl diglycol acetate 5.7 higher-boiling portion and residue 3.9.

Example 3 In the 2 l steel autoclave, as described in Example 1, following batch mixture 1320 g (15 mol) of ethyl acetate 17.9 g (0.07 mol) of zirconium ethylate, Zr * OC2H5) 4 4.0 g (0.04 mol) triethylamine together with 160 ml (3 mol) ethylene oxide Brought to reaction for 4 hours at 160 ° C. and 12 bar.

The substance conversion was 30% by weight with complete ethylene oxide conversion.

After working up by distillation as in Example 1, the product had been obtained Reaction product has the following composition in percent by weight: ethylene glycol monoethyl ether 0.8 dioxane <0.2 ethyl glycol acetate 71.3 ethyl diglycol acetate 19.0 ethyl triglycol acetate 3.8 higher-boiling portion and residue 4.9.

Example 4 In a 2 l steel autoclave, as described in Example 1, following batch mixture 1320 g (15 mol) of ethyl acetate 6.0 g (4023 mol) of zirconium ethylate 1.3 g (0.01 mol) of triethylamine together with 55 ml (1 mol) of ethylene oxide for 4 hours 160 OC and 12 bar brought to reaction.

With complete ethylene oxide conversion, the material conversion was 10 percent by weight.

After working up by distillation as in Example 1, this had been obtained Reaction product has the following composition in percent by weight: ethylene glycol monoethyl ether 0.4 dioxane <0.1 ethyl glycol acetate 89kl: ethyl diglycol acetate 6.1 higher boiling point Share and residue 4.3.

Example 5 In the 2 l steel autoclave, as described in Example 1, following batch mixture 1320 g (15 mol) ethyl acetate 6.2 g (0.01 Mol) zirconium tetraethyl, Zr-tC2H5) 4 0.5 g (0.005 mol) triethylamine together with 160 ml (3 mol) of ethylene oxide reacted for 2 hours at 100 ° C. and 12 bar.

When the ethylene oxide conversion was complete, the conversion was 30 percent by weight.

After working up by distillation as in Example 1, this had been obtained Reaction product has the following composition in percent by weight: ethylene glycol monoethyl ether 0.1 dioxane <0.1 ethyl glycol acetate 65.6 ethyl diglycol acetate 26.1 higher boiling point Proportion and residue 8.1.

Example 6 In a 2 l steel autoclave, as described in Example 1, following batch mixture 1320 g (15 mol) of ethyl acetate 30 g (0.07 mol) of tetrabenzyl zirconium, Zr (CH2-C6H5) 4 4 g (0.04 mol) triethylamine together with 160 ml (3 mol) ethylene oxide Brought to reaction for 2 hours at 160 ° C. and 12 bar.

When the ethylene oxide conversion was complete, the conversion was 30 percent by weight.

After working up by distillation as in Example 1, the obtained had Reaction product has the following composition in percent by weight: Ethylene glycol monoethyl ether 0.3 dioxane <0.2 ethyl glycol acetate 68.9 ethyl diglycol acetate 22.7 higher boiling point Proportion and residue 7.9

Claims (6)

A process for the preparation of carboxylic acid esters of Alkylene glycol ethers by reacting alkylene oxides with carboxylic acid esters in the presence of catalysts, characterized in that the reaction of the alkylene oxides and carboxylic acid ester carried out in the presence of a catalyst consisting of at least an organozirconium compound of the general formula I Zr- (R) n 1 wherein n is the valency of zirconium and the substituents R, which can be the same or different, an alkyl radical or oxalkyl radical with 1 to 4 carbon atoms, aryl radical or oxaryl radical, Alkaryl radical with one or more alkyl groups each with 1 to 4 carbon atoms, aralkyl radical with an alkylene group with 1 to 4 carbon atoms, or a halogen atom, with with the proviso that at most 3 halogen atoms are bonded to the zirconium atom, and optionally a cocatalyst consisting of at least one nitrogen compound from the Group of N-alkyl-carboxamides with a total of 12 carbon atoms, N-alkyl-pyrrolidones with 1 to 4 carbon atoms in the alkyl group, benzotriazoles and the compounds of the general Formula II N (Rt) 3 II in which R1 is hydrogen or a hydrocarbon radical with 1 denotes up to 18 carbon atoms, two substituents R1 also being a cyclic hydrocarbon radical can form. 2. The method according to claim 1, characterized in that ethylene oxide or propylene oxide, carboxylic acid ester of the formula III where R2 is hydrogen or an alkyl group having 1 to 4 carbon atoms and R3 is an alkyl group having 1 to 4 carbon atoms, as well as organozirconium compounds of the formula I where n is 4 and the substituents R are the same and an alkyl or oxalkyl group having 1 to 3 C atoms, a phenyl or oxphenyl group or a benzyl group are used as catalyst, and primary, secondary or tertiary C1 to C4 alkylamines according to formula II are used as cocatalyst. 3. The method according to claim 1, characterized in that the Catalyst is used in an amount of 0.05 to 10 mol%, based on alkylene oxide and the cocatalyst in an amount such that the molar ratio of catalyst to cocatalyst is 0.01 to 10. 4. The method according to claim 1 to 3, characterized in that one Alkylene oxide and carboxylic acid ester are used in a molar ratio of 1: 1 to 1:50 and the reaction at a temperature of 100 to 250 OC and up to a metabolic rate carries out from 1 to 60 wt. 5. The method according to claim 2, characterized in that there is ethylene oxide and ethyl acetate in a molar ratio of 1: 3 to 1:30 in the presence of 0.1 up to 5 mol% catalyst, based on ethylene oxide, and in the present of cocatalyst in such an amount that the molar ratio of catalyst to cocatalyst is 0.1 to 4, converts at a temperature of 130 to 180 OC, the material conversion being brought to 5 to 45% by weight. 6. The method according to claim 5, characterized in that the catalyst is used in an amount of 0.5 to 3 mol%, based on ethylene oxide, and the conversion is carried out to a substance conversion of 10 to 25 parts by weight.