JP2928673B2 - Method for producing benzyl dicarboxylic acid ester - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a benzyl dicarboxylic acid ester.

[0002]

2. Description of the Related Art Hitherto, benzyl dicarboxylic acid esters have been used in various applications such as dyes, paints, sensitizers for photocurable resins or intermediates for pharmaceuticals. This benzyl dicarboxylic acid ester is generally produced by subjecting a benzoin dicarboxylic acid ester to an oxidation reaction in the presence of various oxidizing agents.

As the oxidizing agent used here, for example, copper sulfate-pyridine, nitric acid, chlorine, iodine, sodium hypochlorite, sodium bromate and the like are widely known [Org. Sy.
m. Collective Volume 1 (1967) P87]. However, among them, the method using copper sulfate-pyridine requires a large amount of copper sulfate twice or more moles of the benzoin compound, and the cost is high. Further, there is a problem that it takes time and effort to remove copper sulfate during the post-treatment. Further, the method using nitric acid has a risk that the reaction vessel may be corroded, and the method using a halogen compound has drawbacks such that the effect on the human body cannot be ignored.

[0004]

Accordingly, the present inventors have conducted intensive studies on a method for producing a benzyl dicarboxylic acid ester from benzoin dicarboxylic acid ester easily, cheaply and safely. However, they have found that they can be manufactured in the same manner as before, and have reached the present invention.

[0005]

That is, the present invention provides the following formula (I)

[0006]

Embedded image

[Wherein, R may be the same or different and is an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 5 to 10 carbon atoms, or an aryl group having 6 to 20 carbon atoms. ]
Wherein the benzoin dicarboxylic acid ester represented by the formula is uniformly dissolved or uniformly dispersed in a solvent and reacted while bubbling with a gas containing oxygen.

[0008]

Embedded image

[Wherein, R has the same meaning as in formula (I). ] A method for producing a benzyl dicarboxylic acid ester represented by the formula:

Hereinafter, the present invention will be described in detail.

The aromatic compound used as a raw material in the present invention is a benzoin dicarboxylic acid ester represented by the above formula (I). In the formula (I), R may be the same or different, and may be an alkyl group having 1 to 6 carbon atoms, 5 carbon atoms.
A cycloalkyl group having from 10 to 10 and an aryl group having from 6 to 20 carbon atoms. Specific examples include methyl, ethyl, propyl, butyl, cyclopentyl, cyclohexyl, phenyl, tolyl, naphthyl, and the like. Of these, methyl is preferred as R.

The benzoin dicarboxylic acid ester represented by the formula (I) used in the present invention can be synthesized by a known method. For example, it can be obtained from a corresponding aromatic aldehyde by utilizing a benzoin condensation reaction.

The solvent used in the production method of the present invention may be any solvent capable of uniformly dissolving or dispersing the compound, and ordinary organic solvents can be used. Examples of such a solvent include methanol, ethanol, acetone, dioxane, toluene, xylene, tetrahydrofuran, dimethylformamide, chloroform, dimethylsulfoxide and the like, and among them, ethanol is preferably used. The amount of the solvent is not particularly limited, and may be an amount capable of dissolving or uniformly dispersing the aromatic compound of the formula (I). It is preferable to use about twice.

In the reaction, it is necessary to carry out the reaction while bubbling the reaction solvent with a gas containing oxygen. Here, the gas containing oxygen means a gas containing 5% or more, preferably 10% or more, particularly preferably 15% or more in volume percentage of oxygen gas. The component other than oxygen in the gas may be any component that reacts with the aromatic compound or does not inhibit the intended oxidation reaction.Specifically, nitrogen, argon, helium, carbon dioxide, etc. Can be illustrated. As the oxygen-containing gas, it is preferable to use air or a gas whose oxygen concentration is improved by selectively permeating or adsorbing air.

The method of bubbling a gas into the reaction solution is not particularly limited, but examples thereof include a method of sucking gas from one side of the reaction vessel and a method of using compressed air.

The reaction temperature is not particularly limited as long as the reaction proceeds, but is preferably from 30 ° C. to the boiling point of the solvent.

The reaction time varies depending on conditions such as the reaction temperature, the solvent and the concentration of the raw materials, but is usually 1 to 100 hours, preferably 2 to 50 hours.

According to the present invention, the above formula (II)
Can be obtained, but from the viewpoint of shortening the reaction time or improving the yield, it is also preferable to add a small proportion of the catalyst. Examples of the catalyst include copper compounds such as copper sulfate, copper oxide, and copper chloride.

The addition amount of the catalyst is preferably 30 to 0 mol% based on the benzoin dicarboxylic acid ester of the formula (I),
20 to 0 mol% is particularly preferred. It is also preferable to add an auxiliary agent together with the catalyst in order to increase the activity of the catalyst. Examples of the auxiliary include organic compounds having coordination ability such as pyridine and quinoline. The amount of the auxiliary agent to be added is preferably from 60 to 0 mol%, particularly preferably from 50 to 0 mol%, based on the benzoin dicarboxylic acid ester of the formula (I).

After completion of the reaction, if the formed benzyl dicarboxylic acid ester is insoluble in the solvent used, filtration is carried out.
When soluble, the target compound can be isolated by concentrating the solvent. Further, a compound having high purity can be obtained by using a normal production method such as recrystallization and distillation.

[0021]

According to the present invention, in the process for producing benzyl dicarboxylic acid ester, it is possible to oxidize benzoyl dicarboxylic acid ester in the absence of a catalyst or in the presence of a small amount. Therefore, benzyl dicarboxylic acid esters can be produced inexpensively and effectively. Further, the amount of the metal catalyst used can be reduced, and the environment is safe.

[0022]

The present invention will be described below in detail with reference to examples. In the examples, "parts" means parts by weight. In addition, the infrared absorption spectrum (IR) was measured by a KBr disk method.
The magnetic resonance spectrum (NMR) was measured using deuterated chloroform as a solvent and tetramethylsilane as a standard.

The present invention is not limited by these embodiments.

[0024]

Example 1 100 parts of 4,4'-dicarboxymethylbenzoin and 600 parts of ethanol were placed in a reaction vessel equipped with a stirrer, a condenser and a bubbling tube having a glass filter at the tip, and were uniformly dissolved. The temperature of the reaction solvent was maintained at 60 ° C. while bubbling while introducing air from the other side by suctioning the upper part of the condenser with an aspirator, and the mixture was reacted for 13 hours by stirring. After completion of the reaction, the yellow crystals formed were separated by filtration and recrystallized with dioxane to obtain 50.3 parts of 4,4'-dicarboxymethylbenzyl. The melting point of the compound is 206 ° C., and its IR spectrum and NMR spectrum are shown in FIGS. 1 and 2, respectively.

[0025]

Example 2 A method similar to that of Example 1 was used except that 164 parts of 4,4'-dicarboxymethylbenzoin and 700 parts of ethanol were used, heated to 40 ° C. in an oil bath, and bubbled using compressed air. A time reaction was performed. As a result, 85 parts of 4,4'-dicarboxymethylbenzyl was obtained. The melting point of the compound was 206 ° C.

[0026]

Example 3 Using 164 parts of 4,4'-dicarboxymethylbenzoin and 700 parts of ethanol, the oxygen concentration was adjusted to 40.
The reaction was carried out for 7 hours in the same manner as in Example 2 except that oxygen-enriched air concentrated to% was used. As a result, 4,4'-
87 parts of dicarboxymethylbenzyl were obtained. The melting point of the compound was 206 ° C.

[0027]

Example 4 300 parts of 4,4'-dicarboxymethylbenzoin, 3000 parts of ethanol, 22.5 parts of copper sulfate,
The reaction was carried out for 4 hours in the same manner as in Example 1 using 34 parts of pyridine and 90 parts of water. As a result, 280 parts of 4,4'-dicarboxymethylbenzyl was obtained. The melting point of the compound was 206 ° C.

[Brief description of the drawings]

FIG. 1 is an IR spectrum of 4,4′-dicarboxymethylbenzyl obtained in Example 1.

FIG. 2 is an NMR spectrum of 4,4′-dicarboxymethylbenzyl obtained in Example 1.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI C07C 69/773 C07C 69/773 (56) References Chem. Soc. , 1963, p. 1371-1377 Org. Syn. , Collective volume 1, 1967, p. 87 (58) Field surveyed (Int.Cl. ⁶ , DB name) C07C 69/76 C07C 67/313 C07C 69/773 C07C 45/37 CA (STN) CAOLD (STN) CAPLUS (STN) REGISTRY (STN)

Claims (1)

(57) [Claims] 1. A compound represented by the following formula (I): [Wherein R may be the same or different and has 1 to 1 carbon atoms.
6, an alkyl group, a cycloalkyl group having 5 to 10 carbon atoms,
It is an aryl group having 6 to 20 carbon atoms. Wherein the benzoin dicarboxylic acid ester represented by the formula (II) is uniformly dissolved or dispersed in a solvent and reacted while bubbling with a gas containing oxygen. [Wherein, R has the same meaning as in formula (I). A method for producing a benzyl dicarboxylic acid ester represented by the formula: