JPH0321538B2 - - Google Patents

Description

[Detailed description of the invention]

<Industrial Application Field> The present invention relates to a method for producing succinyl succinic acid diester, and more specifically, to produce succinyl succinic acid diester in high yield and industrially advantageously through a condensation reaction between succinic acid diester and an alkali metal alcoholate. It relates to a manufacturing method. Succinyl succinic acid diester is a compound useful as an intermediate for quinacridone pigments. <Prior art> A method for producing succinyl succinic acid diester has been known for a long time, for example, as described in US Pat. No. 3,024,268.
Specifications and organic chemistry handbook (Gihodo/Showa
47) on page 430 discloses the condensation reaction of diethyl succinate in a solvent such as ethanol and aromatic hydrocarbons in the presence of sodium metal or sodium ethylate. <Problems to be Solved by the Invention> All of these conventional methods relate to the production of ethyl ester, but on the other hand, when methyl ester is the target product, the yield is significantly reduced. That is, when a reaction was attempted according to the method described in U.S. Pat. No. 3,024,268, succinyl succinic acid diethyl ester was certainly obtained with a yield of 80% as described in the example. , 55 for succinyl succinic acid dimethyl ester
It was found that only ~60% yield could be obtained. Therefore, although it is possible to obtain diethyl ester at a yield level of approximately 80% using the conventional method described above, it is extremely inconvenient for dimethyl ester to be carried out industrially. is pointed out. Therefore, an object of the present invention is to provide an industrially advantageous method for producing succinyl succinic acid diester, particularly its dimethyl ester. <Means for Solving the Problems> That is, the present invention provides a solution to a polyalkylene glycol selected from the group consisting of polyalkylene glycol, alkylene glycol alkyl ether, and polyalkylene glycol alkyl ether in a mixed solvent consisting of an aromatic hydrocarbon and a lower alcohol. There is a method for producing a succinyl succinic acid diester, which comprises carrying out a condensation reaction of a succinic acid dialkyl ester in the presence of at least one kind and an alkali metal alcoholate, followed by neutralization. As the raw material dialkyl succinate, lower alkyl esters are generally used, and corresponding succinyl succinic diesters can be obtained, but as raw materials for synthesis of quinacridone pigments, industrially inexpensive methyl esters or ethyl esters are preferred. In particular, methyl esters are economically advantageous. As the alkali metal alcoholate, a sodium or potassium alkyl alcoholate is used, and usually an alcoholate corresponding to the alkyl group of the raw material dialkyl succinate, such as a methylate in the case of methyl ester, is used. The alkali metal alcoholate may be prepared in advance and charged into the reaction system, or may be prepared in advance by reacting an alkali metal and alcohol prior to the condensation reaction. The amount of alkali metal alcoholate used is 1.0 to 2.0 per mole of raw material dialkyl succinate.
It is used in moles, preferably in the range of 1.0 to 1.3 moles. If the amount is less than 1.0 mol, the yield will be poor, and if it exceeds 2.0 mol, the yield will not increase accordingly and it will be uneconomical. The aromatic hydrocarbons used in the present invention include benzene, toluene, xylene, ethylbenzene, etc., and aromatic hydrocarbons have a boiling point of 80 to 150°C under normal pressure and hardly azeotrope with the alcohol produced during the reaction. used. The most distinctive feature of the present invention is that at least one compound selected from the group consisting of polyalkylene glycol, alkylene glycol alkyl ether, and polyalkylene glycol alkyl ether is added to a mixed solvent consisting of an aromatic hydrocarbon and a lower alcohol. It is about making it exist. As the polyalkylene glycol, polypropylene glycol, polyethylene glycol, etc. with a molecular weight in the range of 100 to 3000 are used; as the alkylene glycol alkyl ether, ethylene glycol monobutyl ether, ethylene glycol dimethyl ether, etc. are used; as the polyalkylene glycol alkyl ether, diethylene glycol is used. Specific examples include monobutyl ether, but are not limited to these. The amount of these compounds added is in the range of 1 to 20% by weight based on the raw material dialkyl succinate, and even if the amount exceeds 20% by weight, no significant effect on yield is observed and it is uneconomical. be. The condensation reaction is usually carried out at a temperature of 90 to 150°C, preferably 100 to 150°C.
The reaction is carried out by heating to 130°C, and a sufficient yield can be obtained with a reaction time of about 2 to 20 hours, preferably about 3 to 15 hours. The condensation reaction is carried out while distilling off the alcohol produced, and the dialkali metal salt of succinyl succinic acid diester precipitated from the product thus obtained is neutralized by dropping dilute sulfuric acid, and the precipitated succinyl succinic acid is The diester is filtered and dried to produce a product. Further, the organic solvent layer is separated from the liquid, concentrated, and the precipitated crystals are filtered and dried to efficiently recover the target product. In addition, by reusing the mixed solvent, which is the liquid from which the dialkali metal salt crystals have been removed, in the next condensation reaction, it is possible to further recover the target product remaining dissolved. <Effects of the Invention> As described above in detail, the method for producing succinyl succinic diester of the present invention includes polyalkylene glycol, alkylene glycol alkyl ether, and polyalkylene glycol in a mixed solvent consisting of an aromatic hydrocarbon and a lower alcohol. The method is characterized in that a dialkyl succinate is subjected to a condensation reaction in the presence of at least one selected from the group consisting of alkyl ethers and an alkali metal alcoholate, and then neutralized. As shown, the yield of the target product is significantly improved, and in particular, in the case of dimethyl succinyl succinate, it can be obtained at a high yield that could not be achieved by conventionally known methods. EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but it goes without saying that the present invention is not limited thereto. Example 1 550g ortho-xylene and metallic sodium
Heat 25.3g to 100-105℃, stir, disperse metallic sodium under a stream of _N2 , and add 54.3g of methyl alcohol.
g was gradually added dropwise, and the mixture was further stirred at 10°C for 1 hour to completely dissolve the sodium. Next, polypropylene glycol average molecular weight
Add 15g of 400, then add 146g of succinic acid dimethyl ester, heat at 10°C for 4 hours,
During this time, methanol produced by the reaction was distilled off and recovered. Then add 15% to the precipitated succinyl succinic acid dimethyl ester sodium salt cooled to 50-60 °C.
% aqueous sulfuric acid solution was added dropwise for neutralization, and the precipitated succinyl succinic acid diester was filtered, washed with water, and dried to obtain 76.1 g of crystals (primary crystals). On the other hand, the liquid was separated into an aqueous layer and an ortho-xylene layer, the ortho-xylene was distilled off under reduced pressure, and the precipitated crystals were dried to obtain 19.4 g of crystals (secondary crystals). The total yield of succinyl succinic acid dimethyl ester was 95.5 g, giving a yield of 83.8 mol%. The melting point of this product was 155.1°C. Examples 2 to 5 The same procedure as in Example 1 was carried out except that polyethylene glycol having an average molecular weight of 300, ethylene glycol monobutyl ether, ethylene glycol dimethyl ether, and diethylene glycol monobutyl ether were used instead of polypropylene glycol. The results are shown in Table 1.

[Table] Example 6 The same procedure as in Example 1 was carried out except that ethyl alcohol was used instead of methyl alcohol and 174 g of diethyl succinate was used instead of dimethyl succinate. 84.0 mol%). The melting point of this product was 12.70°C. Comparative Example 1 Succinyl succinic acid dimethyl ester was synthesized in the same manner as in Example 1 except that polypropylene glycol was not used in Example 1. The yield was 68 g (yield 59.6 mol%).

Claims (1)

[Claims] 1. Dialkyl succinate in a mixed solvent consisting of an aromatic hydrocarbon and a lower alcohol in the presence of at least one member selected from the group consisting of polyalkylene glycol, alkylene glycol alkyl ether, and polyalkylene glycol alkyl ether and an alkali metal alcoholate. 1. A method for producing succinyl succinic acid diester, which comprises carrying out a condensation reaction of ester and then neutralizing it.