JPS63107947A - Production of complex ester - Google Patents

Abstract

PURPOSE:To obtain a complex ester together with a dicarboxylic acid diester, by subjecting a dicarboxylic acid and a diol optionally in the presence of a monohydric alcohol to dehydrating esterification reaction to give a complex acid and then subjecting the complex acid to de-esterification reaction with a monohydric alcohol. CONSTITUTION:A diol (e.g. 1,3-butanediol, etc.) shown by formula I (X is diol residue) and a dicarboxylic acid (e.g. adipic acid, etc.) shown by formula II (A is dicarboxylic acid residue) are subjected to dehydrating esterification reaction in a molar ratio of 1:2.5 optionally in the presence of a monohydric alcohol (e.g. 2-ethylhexanol, etc.) shown by the formula ROH (R is alcohol residue) by the use of a titanium catalyst (preferably solid polytitanic acid) to give a ester carboxylic acid shown by formula III or an ester thereof when the monohydric alcohol is present. Then the ester carboxylic acid or the ester thereof is reacted with a dicarboxylic acid to give a complex acid shown by formula IV or an ester thereof when a monohydric alcohol is present. Further the complex acid is reacted with a monohydric alcohol to give a dicarboxylic acid diester shown by formula V and a complicated ester shown by formula VI.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides low volatility and high plasticizers, lubricating oils,
Alternatively, the present invention relates to a method for producing composite esters that can be used as monomers for copolymerization.

[Prior Art] In this specification, the complex ester refers to a dicarbonate represented by the general formula [11] and a diol (
HOXOH) and a monofunctional alcohol (ROM) C, in which the residues of a dicarboxylic acid, a diol, and a monofunctional alcohol are represented by A, X, and R, respectively.

ROCOACOOXOCOACOOR [[] Substances with that structural formula have already been studied in the production of lubricating oils, for example, US Pat. Such complex esters are described as That is, it is described that the desired product is obtained by dehydrating and esterifying 2 moles of dicarboxylic acid, 1 mole of diol, and 2 moles of monofunctional monoalcohol. It was found that the generation rate was less than 50%. The complex ester product of the above US patent is obtained as a mixture with a complex ester oligomer described by RO(COACOOXO)ncOOR[II],
As a matter of course, it is true that the bis compound described as a composite ester [1 co (structurally, it has a bis structure, so it will be referred to as a bis compound) where n = 1 can be obtained in the largest amount. Oligomers corresponding to n=2+ n=3+ n=4 are produced as by-products, and although the number of oligomers with n=2 or more is small, the weight ratio of the bis compound with n=I in the product is 50 because the molecular weight becomes large. %.Based on this fact, for the purpose of mainly producing bis-compounds, we have previously carried out dealcoholization between diesters of dicarboxylic acids and diols by the transesterification method to obtain products. Attempts were made to reduce the amount of the bis compound by half unless the amount of diester was at least 4 moles or more in the reaction.
The inventor of the present invention found that the proportion of high molecular weight esters increases as the number of moles decreases to 2 moles, and the present inventors described this in JP-A-60-45547.

On the other hand, the inventor of the present application has conducted a dehydration esterification reaction by reacting a dicarboxylic acid, a diol, and a monoalcohol to form an ester alcohol [m] and a dicarboxylic acid diester [IV].
] and perform dealcoholization between these compounds to perform a transesterification reaction.ROCOACOOXO)I E mco + nROcO
AcOOREIV] = [11] + ROH It was discovered that the desired complex ester [I[] could be produced, and the production method was disclosed in JP-A No. 61-7644.
2.

[Problem to be Solved by the Invention (1)] The compound represented by the ester alcohol ROCOACOOXOH [III], which can be produced by the reverse reaction of the complex ester produced above with the Ichinomiya functional alcohol, has a high concentration depending on the types of R and X. Although the molecular weight is low volatility, the stabilizer in polyvinyl chloride acts as a catalyst for this substance, and a low volatility alcohol is produced by transesterification with the ester group of the coexisting plasticizer. Since the amount of volatilization increases, it is inappropriate to use a complex ester containing ester alcohol [II[] as a plasticizer, and it is necessary to remove as much ester alcohol as possible from the plasticizer.

[Means for Solving the Problem (1)] Based on the research results of these manufacturing methods, the present inventor further investigated the methods described below, and as a result, the following method was developed.
The present invention has been completed by discovering that the most excellent method can be obtained by utilizing the two manufacturing techniques disclosed in JP-A No. 45547 and JP-A No. 61-76442.

The reaction process of the present invention is sequentially described. In the presence of a small amount of a monofunctional alcohol, a dicarboxylic acid and a diol are reacted in equimolar amounts, and an ester carboxylic acid containing a compound partially esterified with a monofunctional alcohol is obtained. Complex acids HOCOACOOXOCOA, including those partially esterified with a monofunctional alcohol by reacting with a dicarboxylic acid in an excess of dicarboxylic acid to form HOCOACOOXOH
COOH is produced and then dehydrated and esterified with a complex acid and a functional alcohol to form a complex ester ROCOACOOX.
Generate OCOACOORCII. As a side reaction, the above-mentioned ester carboxylic acids that are intermediate in this reaction react, and when a monofunctional alcohol further reacts with this, 1)
0COACOOXOH→HO(COACOOXO)nH
−+ As in [II], a complex ester oligomer [■] is finally produced as a by-product through a polymer acid or an oligomer acid. To prevent this reaction it is necessary to use an excess amount of dicarboxylic acid.

On the other hand, the presence of a monofunctional alcohol will suppress the formation of oligomers, but if an excessive amount of alcohol is used, the aforementioned ester alcohol ROCOACOOXOH [
111] and the dicarboxylic acid diester ROCOACOOR[rVco are produced. Although the method of industrially producing by-products is not a good method, the by-product dicarboxylic acid diester [IV]
is first described in Japanese Patent Application Laid-open No. 60-455 by the inventor of the present application.
47, a complex ester is obtained by transesterification with a diol, and a partially by-produced ester alcohol [ml is the above-mentioned Japanese Patent Application Laid-open No. 61-7644 by the inventor of the present invention]
[11] was obtained using the transesterification method with a dicarboxylic acid diester using method 2.

The diol is thus added to the excess dicarboxylic acid to form the ester carboxylic acid HOCOACOOX as described above.
Oh.

This initiates a dehydration esterification reaction that appears to form the complex acid HOCOACOOXOCOACOOH which reacts with the dicarboxylic acid, and the monofunctional alcohol is not added at the beginning of the reaction or is added in a suppressed amount, e.g. A monofunctional alcohol less than 1/2 of the stoichiometric amount is added, and a required amount of monofunctional alcohol that is less than the stoichiometric amount is sequentially added to the reaction system to form a dehydrated ester between the above complex acid and the monofunctional alcohol. The reaction of monofunctional alcohol is approximately 9
At the end of the reaction, which has progressed to 0%, a slight excess amount is added to proceed with the reaction to produce the complex ester ROCOACOOXOCOACOOR, and its reverse reaction ROCOACOOXOCOACOOR+ROIl-R
While minimizing the production of ester alcohol [ml] by OCOACOOXOH+ROCOACOOR, the acid value is brought to a sufficiently low value, that is, the reaction is allowed to proceed.

Ester alcohol still remains as a by-product [I11]
is prevented from forming by carrying out a transesterification reaction between the dicarboxylic acid and the monofunctional alcohol with the dicarboxylic acid diester produced as a by-product. That is, by heating under reduced pressure to perform dealcoholization and transesterification with the aid of a titanium catalyst as a catalyst for the dehydration esterification reaction, the ester alcohol [ ] produced as a by-product can also be converted into the target compound ester.

As mentioned above, the removal of the ester alcohol is important. In other words, the compound represented by ROCOACOOXOH[III] may have a high molecular weight and low volatility depending on the types of R and Complex esters containing ester alcohols [ml] are unsuitable for use as plasticizers because transesterification occurs with ester groups to produce low-volatility alcohols and increase the amount of volatile matter. It is. Therefore, it is necessary to remove as much ester alcohol as possible from the plasticizer.

That is, the present invention is based on the technology of preventing the formation of ester alcohol by suppressing the initial amount of monofunctional alcohol added, and also on the above-mentioned two technologies, namely, JP-A-60-455.
47 and JP-A No. 61-76442, it is believed that although the industrially disadvantageous dicarboxylic acid diester is produced as a by-product, it is an excellent method for producing the target compound ester. . The present invention performs a dehydration esterification reaction using a titanium catalyst together with a dicarboxylic acid in an amount of at least 2.5 moles or more and 3.5 to 5 moles per mole of polyol, and the above-mentioned suppressed amount of monofunctional alcohol. The present invention relates to a method for producing a composite ester together with a dicarboxylic acid diester by starting a dehydration esterification reaction by adding a required amount of monofunctional alcohol (the amount added is increased at the end of the reaction).

[Problem to be solved by the invention (2)] The production method for composite esters is good or bad depending on how much the production ratio of the pure bis compound El in the product is increased. To achieve this, it is necessary to increase the amount of dicarboxylic acid, but the only way to reduce the amount of dicarboxylic acid used in the three components is to use dicarboxylic anhydride to selectively form a half-ester. Even in some cases, oligomers are formed as by-products, increasing the viscosity of the product. If a large amount of dicarboxylic acid is used, it will naturally be necessary to remove or reuse the diester, so using a large amount of dicarboxylic acid is not a desirable method, and therefore there is no point in using a large amount of dicarboxylic acid. It's here. However, it has been found that by using the method described above in combination and converting the by-product diester into a composite ester, it is possible to increase the manufacturing unit consumption and obtain a product that is comparable in quality.

[Problem to be solved by the invention (3)] In the esterification reaction of acids using alcohol, esterification progresses in proportion to the removal of water in the dehydration reaction. An excessive amount of alcohol is used. If there is insufficient alcohol, acid remains and the acid value of the ester does not decrease, and when it is made into a product with a high acid value, physical properties such as electrical properties, water resistance, and chemical resistance deteriorate. is required. Similar to other high molecular weight polyesters, if the acid value of complex esters is high, even if you try to remove the acid with alkali washing, the salt formed with the acid will act as an emulsifier, resulting in poor oil-water separation, and the alkali salt will It is easy to eliminate this phenomenon, where the acid value is not dispersed in the oil and is not removed, and even after repeated alkaline and hot water washing, the acid value does not become low, or even if it does, it is very time consuming and difficult. In order to obtain a low acid value ester, it is naturally necessary to use a low acid value ester mixture during production.

The present inventor conducted research on this problem and found that solid polytitanium acid catalysts have the ability to lower the acid value compared to soluble titanium catalysts. 219140, patent application 1986-28
0220 and Japanese Patent Application No. 61-132618.

That is, in a solid polytitanic acid catalyst, alcohol adsorption is very fast, and the rate-limiting reaction is acid adsorption, so the acid value decreases in linear proportion to the acid concentration. On the other hand, in the case of soluble alkoxytitaniums, alcohol adsorption is also rate-limiting, depending on the type of alcohol, resulting in a secondary or higher order reaction, so the acid value ultimately does not decrease as much as expected over time. The amount of alcohol used naturally controls the reaction rate, so we want to increase the alcohol concentration and lower the acid value.
In the complex ester system, a transesterification reaction occurs using a titanium catalyst, and the reverse reaction shown by the following formula also proceeds to produce ester alcohol [III] in the product.

ROCOACOOXOCOACOOR[I] +Ro
o+ROCOACOOXO)l [[] +ROCOA
COORThis reaction is particularly likely to occur at a relatively low acid value, which corresponds to the final stage of the esterification reaction, and therefore it is preferable to increase the reaction rate.However, in order to increase the reaction rate, excess alcohol may be added from the beginning of the reaction. It is not preferable to carry out the reaction in a state where ester alcohol is likely to be formed.

In addition, in order to obtain a high-quality ester with a low acid value, such a reaction must occur to some extent, so it is absolutely necessary to return the ester alcohol [ml] once produced.

[Means for Solving the Problems (2) and (3)] It has been found that the above problems can be solved very easily if the specific manufacturing method uses the techniques already described.

That is, a diol is added to a large excess of dicarboxylic acid, and in some cases, a portion of a monofunctional alcohol is added to start the dehydration-esterification reaction, and the necessary amount of monofunctional alcohol is added in proportion to the amount of dehydration. When performing an esterification reaction, even if the monofunctional alcohol is butanol, which has a low boiling point, the dehydration and esterification reaction proceeds at a relatively high temperature, and as a result, the reaction rate is high and the esterification proceeds. After reducing the acid value as much as possible, the reaction solution is transferred to a vacuum heater and further transesterified with an excess monofunctional alcohol under reduced pressure to remove the produced alcohol. Any titanium catalyst can be used for the transesterification reaction, and the higher the degree of vacuum, the better.
Heating at a temperature of 140-200°C is required, but the lower the temperature, the slower the heating rate.

Using a large excess of monofunctional alcohol will result in the production of ester alcohol [ml] as mentioned above, but even without using a large excess, the reaction rate is sufficiently fast with a polytitanic acid catalyst, and even with the use of alkoxy titanium. Partial addition of alcohol can increase the reaction temperature and speed up the reaction rate. In particular, it is recommended to partially add an excess amount of alcohol to the reaction system in the final stage of the reaction when less water is distilled out, and when 80 to 95% of the acid has reacted, the minimum amount necessary to lower the acid value is added. is necessary.

If the temperature is sufficiently high and the pressure is sufficiently low after removing the excess alcohol, 30 minutes to 1 hour is sufficient for the transesterification reaction, and the alcohol produced is distilled off little by little. The ester mixture esterified in this manner has a large amount of diester produced as a by-product depending on the amount of dicarboxylic acid used, and the molecular weight of the composite ester becomes small.

Although dehydration and esterification reactions may be possible to achieve extremely low acid values using polytitanic acid catalysts, generally a titanate or alkoxy titanium catalyst is used to reduce the acid value until the acid value is 0.05 or less. Therefore, by washing with a very small amount of alkali and hot water after decatalyzing, low acid value esters can be easily converted into products with low acid values, and high molecular weight esters with extremely low acid values. can be made. Then, the dicarboxylic acid diester is removed by distillation, and the complex ester [II] is obtained as a residual liquid. The viscosity of this composite ester becomes lower as the content of the bis compound increases, and the plasticizing efficiency when used as a plasticizer changes depending on the viscosity, and the lower the viscosity, the higher the plasticity.

When used as a plasticizer, it may be a mixture with a diester, and the volatile content decreases depending on the amount of the high-boiling complex ester, so the complex ester can also be used as a mixture with a diester.

On the other hand, a large amount of by-produced diester can be converted into a composite ester by direct transesterification using diols and a titanium catalyst. This technology and the previously mentioned JP-A-60-4
To restate the differences in the technology of 5547, the amount of monofunctional alcohol used and the reaction route (IllI order) are different, and this method uses monofunctional alcohol in the low acid value region at the end of the reaction. This method uses the minimum necessary excess amount, specifically 0.05 to 0.5 mole amount. As is the case in the prior art where a large excess of monofunctional alcohol is used as the amount needed to produce ester alcohol [ml plus the amount needed to give a low acid value] Therefore, a technique for partially transesterifying and removing the ester alcohol is also used to produce a composite ester.

The catalyst used may be an alkoxy titanium, but is most preferably a polytitanic acid catalyst. As already mentioned, polytitanic acid catalysts have the advantage of having a low acid value, and their catalytic activity is equal to or higher than that of alkoxy titanium, and the catalyst can be easily removed by filtration after the reaction is completed. In some cases, it may be used as a plasticizer.

The polytitanic acid catalysts shown in the examples were produced as follows according to the method for producing polyol polytitanic acid catalysts having a polytitanic acid structure.

1 mole of tetrabutoxytitanium is added to a mixture of 3 moles of 2-ethylhexanol and 1 mole equivalent of pentaerythritol and heated, resulting in 4 atoms of titanium per mole of pentaerythritol and 3 atoms of 2 atoms per mole of titanium. The reaction is carried out under heating in the proportion of ethylhexanol to sufficiently remove butanol, and then a 1.5 molar amount of a water-butanol solution is added, and the 2-ethylhexanol produced is heated under reduced pressure to sufficiently remove and increase the A solid polytitanic acid catalyst obtained by molecularization and hyper-crosslinking to produce a polyol polytitanic acid having a polytitanic acid structure and activation by heating and stirring with an excess amount of water-butanol at 80-85° C. was used.

The dicarboxylic acids, diols, and monofunctional alcohols used may be any conventionally known compounds; adipic acid is used as the dicarboxylic acid for economical reasons, but succinic acid, geltaric acid, azelaic acid, and speric acid can also be used. etc. and mixtures thereof may also be used. The diol is ethylene glycol, l.

2-propanediol, 1.3-propanediol, l
.

2,2- such as 3- or 1,4-butanediol, l,6-hexanediol and neopentyl glycol
Substituted or 1,2-substituted 1,3-propanediol or diethylene gellicol, triethylene glycol, dipropylene glycol, tripropylene glycol, thiodiglycol, etc. are used. The monofunctional alcohol most commonly used is butanol or 2-ethylhexanol, but it may also be an oxo-produced alcohol having a straight or side chain of 6 to 9 carbon atoms.

Examples will be described below, but the three-component silk combination is not limited to the description of the examples.

Example 1 - ? −shi
-234g
of adipic acid (1,6 mol), 36 g (0,4 mol) of 1,3-butanediol and 20 g of 2-ethylhexanol.
8 g (1.6 mol) and 0.8 g of a polyol polytitanic acid catalyst having a polytitanic acid structure were added, and the mixture was placed in an azeotropic dehydration esterification apparatus and heated, and a dehydration esterification reaction was started together with a small amount of toluene. From the point when -3/3 of the calculated amount of water comes out, the remaining 2-ethylhexanol 104
The reaction was carried out while adding 58 g, and finally an excess of 58 g was added. After 3 hours, approximately the calculated amount of water was distilled out and the acid value was 1.3.
Tonafuta. After 4.5 hours, the acid value decreased to 0.03, and the esterification reaction solution was transferred to a vacuum heating device to distill excess octatool, and then heated at 3 m m H for another 1 hour.
A substantially quantitative amount of 2-ethylhexanol was recovered by stirring at 180° C. under reduced pressure of H.

It was then washed with an alkaline aqueous solution containing 0.2 g of caustic soda and hot water, distilled under reduced pressure, and heated to 150-180'C.
10.3mm+ dioctylazibe) (D OA
) was recovered, and 180 g of 1,3-butanediol bis-2-ethylhexyl adipate was obtained as a residual liquid. The viscosity of this product at 20°C is 70 centiboise, and the analysis results by liquid chromatography show that it is about 65% bis compound with formula [■] and n = 2.3. It was a mixture of the compound of n=4 and an extreme amount of the compound of n=4.

Soft polyvinyl chloride resin 100 with a polymerization degree of 1050
2 parts of dibutyltin maleate and 0.15 parts of dibutyltin maleate as a stabilizer as well as 50 or 80 parts of the plasticizer, and kneaded for 3 minutes with a roll kneader at 160-165°C. Then 100 at 170-175℃
A 1 mm sheet was produced by press molding under atmospheric pressure. The surface hardness of each of these 50PI (R and 80PHH sheets) was measured after being left at 21°C for 48 hours, and 50PHR and 80PHR were measured using DOP as a standard.
Find the average distance from the reference line created by connecting the values obtained on the PHR sheet, draw a line parallel to the reference line, and calculate DOPf5.
The amount of plasticizer that gave the same hardness as that of 0 PHR was determined. This value will be described below as plasticization efficiency. Its value was 45. That is, using 45 parts of plasticizer had the same effect as using 50 parts of DOP. Also 100℃
The results of a 7-week heating test showed that the surface hardness was almost unchanged and there was no volatility even when used as a plasticizer, indicating excellent properties.

Example 2 - - Gu - Shi
292 g (2 mol) of Shipabe-adipic acid and 45 g of 1,4-butanediol (
0.5 mol) and 74 g of butanol (1 mol) were added, and 0.8 g of polytitanic acid catalyst was added to start the dehydration esterification reaction. From the moment 18 ml (1 mol) of water comes out,
The remaining amount corresponds to the amount of water produced by dehydrating butanol.
The addition was terminated when 48 g (2 moles) were added and 50 ml of water was distilled off. When an additional 65 ml was distilled, the excess amount was 40
g was added dropwise. The reaction temperature of this dehydration esterification reaction was approximately 180-200°C. 195-200℃
The mixture was heated and stirred for 6 hours, and approximately the calculated amount of water was distilled out, and the acid value at that time was 0.2, and after 10 hours it was 0.05.
Met. 25mdg of the reaction solution was heated and stirred at 180°C for 1 time.
The butanol produced over time was removed. 3 at 85℃
ml of water was added, stirred for 1 hour, filtered to remove catalyst residue, washed with water containing a very small amount of alkali and hot water, and distilled under reduced pressure. 117-120℃70.3mm
260 g of dibutyl adipate (DBA) was obtained using Hg, and 165 g of 1,4-butanediol bisbutyl adipate was obtained as a residual liquid. The viscosity at 21"C was 45 centimeters. The plasticization efficiency was 43, and the loss on heating of the plasticized vinyl chloride sheet at 170°C for 3 hours was 3.2.
%, slightly volatile, but DBA, DOA, D'
Compared to BP and DOP, it had very little high plasticity and low volatility.

Example 3 234 g (1.6 mol) of thiodiglycol (49 g)
0,4 mol) and 82 g n-hexanol (0,8
mol) was added to start the dehydration esterification reaction in the presence of 0.8 g of polytitanic acid catalyst. When 1 mol of water was released, 163 g (1.6 mol) of hexanol residue and 45 g (0.4 mol) of excess hexanol were added to carry out the dehydration esterification reaction, and as a result, the 3-hour acid soaking value was 1. to .0,
After 3.5 hours, it became 0.05. After 4 hours, distillation was performed under reduced pressure to remove excess hexanol, and 180-
The mixture was heated and stirred at 190'C/25 mmHg for 50 minutes to remove generated hexanol and carry out a transesterification reaction.

Add 3 ml of water, stir at 70°C for 1 hour, add 10 g of activated clay, filter, and then wash with water containing 40 mg of caustic soda and hot water to give an acid value of 0.03. Dihexylazibe) (DHP) 151-157℃10.
282 g of 3 mm Hg was distilled to obtain 164 g of thiodiglycol bis-n-hexyl adipate as a residual liquid.

The viscosity at 21° C. was 91 centivoice, the plasticizing efficiency was 40, and the result of heating at 100° C. for 7 weeks showed excellent plasticity and volatility resistance and weather resistance, making it a preferred plasticizer.

Claims (3)

[Claims] (1) A diol of the formula HOXOH [wherein X is a diol residue] and a 2.5 mol or more amount of the formula HOCOACO per 1 mol of this diol.
OH [in the formula, A is a dicarboxylic acid residue] dicarboxylic acid and the dicarboxylic acid, initially from 0 to 1/1 of the stoichiometric amount.
In the presence of a monofunctional alcohol with the formula ROH of less than 2 [wherein R is an alcohol residue], a titanium-based catalyst is used to carry out a dehydration esterification reaction, and the ester carboxylic acid of HOCOACOOXOH and the monofunctional alcohol are initially present. When a small amount of the monofunctional alcohol is present, the ester carboxylic acid is reacted with the excess dicarboxylic acid in situ to form the complex acid HOCOACOOXOCOACOOH and when the monofunctional alcohol is initially present. forms an ester with a small amount of its monofunctional alcohol, while adding the monofunctional alcohol ROH so that the amount of the dicarboxylic acid is always less than the stoichiometric amount until near the completion of the reaction. A method for producing a complex ester ROCOACOOXOCOACOOR together with a dicarboxylic acid diester ROCOACOOR by subjecting a functional alcohol to a dehydration esterification reaction. (2) The production method according to claim 1, wherein the catalyst used is an alkoxytitanium or a solid polytitanic acid produced from an alkoxytitanium. (3) The method for producing a composite ester according to claim 1, wherein the esterification reaction is carried out by adding an excess amount of monofunctional alcohol at the very end of the dehydration esterification reaction.