JPS6151594B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing cis-epoxysuccinic acid ester. More specifically, in the esterification reaction using cis-epoxysuccinic acid or its salt as a starting material, by using an acid with a nucleophilic constant of 1.0 or less as a catalyst, there are no by-products, high yield, and a low reaction rate. The present invention provides a fast, industrially excellent and advantageous method for producing cis-epoxysuccinic acid ester. Cis-epoxysuccinic acid ester is an industrially important raw material as a builder crosslinkable polymer for polyamides and detergents. As a conventional reaction for obtaining cis-epoxysuccinic acid ester, it is known, for example, in Japanese Patent Publication No. 36248/1983, to carry out an esterification reaction of cis-epoxysuccinic acid in an alcohol solvent using hydrochloric acid as a catalyst. The present inventors carried out an esterification reaction using hydrochloric acid to synthesize cis-epoxysuccinic acid ester. The results are shown in Comparative Example 5, which will be described later.
Cis-epoxysuccinic acid has an oxirane ring as a functional group, so it is a 2-epoxysuccinic acid with hydrochloric acid added to it.
A considerable amount of chloro-3-hydroxysuccinic acid ester is produced as a by-product. Since the boiling point of this by-product is very close to the boiling point of the target cis-epoxysuccinic acid ester, it has the drawback that it cannot be separated by simple distillation, and this method cannot necessarily be said to be industrially advantageous. The present inventors conducted statistical research to compensate for the shortcomings of the conventional methods, and as a result, they found that the production of the above-mentioned byproducts and the reaction rate are greatly affected by the type of acid used as a catalyst. As a result of further research, it was discovered that the counter anion of the acid used as a catalyst plays an important role in the production of the above-mentioned by-products, leading to the completion of the present invention. The present invention is a cis-epoxy succinic acid ester characterized by using an acid having a nucleophilic constant of 1.0 or less as a catalyst when producing a cis-epoxy succinic acid ester by reacting cis-epoxy succinic acid or a salt thereof with an alcohol. This is a method for producing succinic acid ester. The cis-epoxysuccinic acid or salt thereof used in the present invention is not particularly limited, and any known one can be used as is. The method for producing cis-epoxysuccinic acid and its salts is not particularly limited and may be obtained by any method, but generally it is obtained by epoxidizing maleic acids with hydrogen peroxide in the presence of a tungsten catalyst. is preferably used. As the salt of cis-epoxysuccinic acid used in the present invention, either an acid salt or a normal salt can be used. Acid salts of alkali metals, alkaline earth metals, etc., such as sodium salt, cis-epoxy hydrogen succinate 1/2 calcium salt, cis-epoxy sodium hydrogen succinate 1/2 calcium salt, cis-epoxy hydrogen potassium salt, etc. Normal salt etc. can be suitably used. Further, the alcohol used in the present invention is not particularly limited as long as it reacts with the cis-epoxysuccinic acid or its salt to produce a cis-epoxysuccinic acid ester during the reaction of the present invention.
In general, lower alcohols such as methanol, ethanol, propanol, butanol, etc. are preferably used. The most important feature of the present invention lies in the catalyst used when reacting cis-epoxysuccinic acid or its salt with alcohol. That is, the catalyst used in the present invention needs to be an acid with a nucleophilic constant of 1.0 or less. The nucleophile constant is, for example, “Acids and Bases” by Yoshiyuki Okamoto, published by Tokyo Kagaku Dojin Co., Ltd. (January 1967).
It is detailed on pages 90-91 (published on the 25th) and is already well known. However, the present invention is the first to establish the influence of acid catalysts used in the production of esters from cis-epoxysuccinic acid or its salts and alcohols. As mentioned above, in the above-mentioned esterification reaction, by-products generated by addition to the oxirane ring of cis-epoxysuccinic acid or its salt pose a problem. The catalyst used in the present invention has a nucleophilic constant of 1.0 as described above.
As it is small, there is almost no by-product reaction added to the oxirane ring, and the esterification reaction is very fast. Therefore, the selectivity of cis-epoxysuccinic acid ester is extremely high, and it can be said that it is an industrially excellent catalyst. The nucleophilic constant of the catalyst is
If an acid catalyst larger than 1.0 is used, reaction by-products will be generated as described above, which will not only reduce the selectivity of cis-epoxysuccinate ester but also increase the
The production reaction rate of epoxysuccinate ester also varies depending on the type of catalyst and is not necessarily determined by the size of the nucleophile constant. Although this phenomenon is not necessarily clear, the present inventors believe that the behavior of acids as catalysts in alcohol is not limited, and that the formation of by-products has some adverse effect on the formation of cis-epoxysuccinate. I suspect that there are. The catalyst used in the present invention is not particularly limited as long as it is an acid with a nucleophilic constant of 1.0 or less as described above, but perchloric acid, perbromic acid, periodic acid, Para-toluenesulfonic acid and the like are preferably used. The esterification reaction of cis-epoxysuccinic acid or its salt and alcohol in the present invention is not particularly limited and can be carried out under known reaction conditions. For example, the reaction temperature is generally below the boiling point of the alcohol, preferably between room temperature and the boiling point of the alcohol. Further, the raw material ratio of cis-epoxysuccinic acid or its salt and alcohol in the present invention is not particularly limited and may be selected according to a general esterification reaction. In general, the molar ratio of alcohol is 10
It is suitable to use it in a range of 200 to 200 times the mole, preferably 20 to 100 times the mole. Further, the amount of the catalyst used as the catalyst of the present invention varies depending on the type of starting materials, reaction type, etc., and cannot be absolutely limited. Generally, when cis-epoxysuccinic acid is used as a starting material, the H proton of the catalyst is preferably used in an amount of 0.02 to 4 molar equivalents, preferably 0.10 to 2.0 molar equivalents, per mole of cis-epoxysuccinic acid. Further, when using cis-epoxysuccinate as a starting material, it is preferable to select an equivalent amount including the amount of acid necessary to convert the cis-epoxysuccinate to cis-epoxysuccinic acid. EXAMPLES The present invention will be specifically explained below with reference to Examples, but the present invention is not limited to these Examples. Examples 1 to 2 and Comparative Examples 1 to 4 1.32 g (10 mmol) of cis-epoxysuccinic acid was dissolved in 20 ml of dry methanol, and 1 mmol of the catalyst shown in Table 1 was added thereto. _0.5mMol for _H2SO4
added. The mixture was placed in an L-shaped test tube with a capacity of 50 ml, and the mixture was shaken and stirred at 30°C. Analysis was performed using gas chromatography. (SF-30 5% Column length 1.5m Column temperature
160℃)

[Table] Comparative Example 5 6.60 g (0.05 mole) of cis-epoxysuccinic acid was dissolved in 25 g of dry methanol, 25 g of 9.21 wt/wt% hydrogen chloride-methanol was added, and the mixture was stirred at room temperature for 2 days. Excess methanol was distilled off under reduced pressure, and the residue was extracted with 100 ml of ethyl acetate, washed with water, washed with a cold 5% aqueous sodium bicarbonate solution, washed with water again, dried over Glauber's salt, and analyzed by gas chromatography. As a result, the by-product 2-chloro-3-hydroxysuccinic acid dimethyl ester was found to have a molar ratio of 2-chloro-3-hydroxysuccinic acid dimethyl ester to cis-epoxysuccinic acid dimethyl ester.
It was generated at a ratio of 50.9:49.1. Example 3 6.60 g (0.05 mole) of cis-epoxysuccinic acid was dissolved in 50 ml of dry methanol, and 70 wt% HClO ₄ was added.
2.00g was added and stirred at room temperature for 2 days. The same operation as in Comparative Example 5 was carried out, and from the obtained solution of ethyl acetate, ethyl acetate was distilled off under reduced pressure.
7.05g of liquid was obtained. Gas chromatography, IR, NMR, and elemental analysis revealed that it was 100% pure cis-epoxysuccinic acid dimethyl ester. Example 4 6.60 g (0.05 mole) of cis-epoxysuccinic acid was dissolved in 80 ml of dry ethanol, 0.86 g of para-toluenesulfonic acid was added, and the mixture was stirred at 40° C. for 2 days. After distilling off excess ethanol under reduced pressure, Comparative Example 5
The same treatment as above was carried out to obtain 8.47 g of cis-epoxysuccinic acid diethyl ester. Example 5 cis-epoxy sodium hydrogen succinate 7.70g
(0.05 mole) to 100 ml of dry methanol, and
10.05 g of 70wt% HClO ₄ was added and stirred at 40°C for 2 days. After filtering the precipitate, excess methanol was distilled off under reduced pressure and the same treatment as in Comparative Example 5 was performed to obtain 6.97 g of cis-epoxy dimethyl succinate. Example 6 Disodium cis-epoxysuccinate 8.80g
(0.05 mole) to 100 ml of dry methanol, and
17.22 g of 70wt% HClO ₄ was added and stirred at 40°C for 2 days. After precipitation, excess methanol was distilled off under reduced pressure, and the same treatment as in Comparative Example 5 was performed to obtain 6.88 g of cis-epoxysuccinic acid dimethyl ester.

Claims (1)

[Claims] 1. When producing a cis-epoxysuccinic acid ester by reacting cis-epoxysuccinic acid or its salt with an alcohol, a catalyst having a nucleophilic constant
A method for producing cis-epoxysuccinic acid ester, characterized by using an acid of 1.0 or less. 2. The method according to claim 1, wherein the catalyst is perchloric acid. 3. The method according to claim 1, wherein the catalyst is para-toluenesulfonic acid.