JP3433766B2 - Method for producing acyclic esters having an aromatic group - 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 acyclic esters having an aromatic group by subjecting an acyclic ketone having an aromatic group to liquid phase oxidation.

[0002]

Acyclic esters having an aromatic group are
It is a useful substance used for various industrial chemicals such as solvents, functional resins, and pharmaceuticals, and their synthetic intermediates.

As a method for synthesizing an ester corresponding to an acyclic ketone having an aromatic group, the Bayer-Villiger reaction is still general. Since this reaction is a homogeneous reaction, it is difficult to separate products, and an expensive peracid is used, which is economically disadvantageous.

As a reaction similar to the Bayer-Villiger reaction, Japanese Examined Patent Publication No. 39-5921 and Japanese Unexamined Patent Publication No. 53-255.
16, JP-B-55-36667 and JP-A-5-6.
Japanese Patent No. 5245 describes a method for producing a lactone from an alicyclic ketone. However, in all of these publications, the final end product is limited to lactone, and there is no description about a method of synthesizing an ester corresponding to an acyclic ketone having an aromatic group. The publication also includes the problem of toxicity due to the catalyst.

[0005]

DISCLOSURE OF THE INVENTION The present invention is capable of obtaining acyclic esters having an aromatic group in a high yield under mild reaction conditions, and there is no toxicity due to the catalyst. It is an object of the present invention to provide a new production method which can be easily separated.

[0006]

Means for Solving the Problems In order to solve the above-mentioned problems of the prior art, the inventors of the present invention have conducted extensive studies on the catalyst used during the reaction. As a result, the inventors have obtained the knowledge that the problems of the prior art can be solved only by using a specific catalyst, and completed the present invention.

That is, the present invention provides a method for producing an acyclic ester having an aromatic group by liquid phase oxidation of an acyclic ketone having an aromatic group in the presence of a catalyst, aldehydes and oxygen. Is a solid base catalyst, and relates to a process for producing acyclic esters having an aromatic group.

As the acyclic ketone having an aromatic group, which is a raw material in the present invention, various known ones can be used without particular limitation. Specific examples thereof include 4-methoxyacetophenone, 2-ethoxy-2-phenylacetophenone, benzoylacetone, o-benzoylbenzoic acid, 2-benzoylpyridine, benzophenone, propiophenone, pentophenone, 4-methoxyphenylcyclopropyl. Examples thereof include ketone, cyclopentylphenylbutanone, phenylhydrazone, myristophenone, butyrophenone, chlorophenylethanone, fluorophenylmethanone, bromophenylbutanone, 1-phenyldodecaffenone, and heptanophenone.

The basic solid catalyst used in the present invention includes alkali metal oxides such as Na ₂ O, K ₂ O, Rb ₂ O and Cs ₂ O; alkaline earth metals such as MgO, CaO, SrO and BaO. Oxides: La ₂ O ₃ , ZrO ₂ , ThO ₂ ; Na-Al ₂ O ₃ , alkali metal-supported oxides such as K-SiO ₂ ; Na-Y, Na-mordenite, Na-Z
Examples thereof include alkali metal-exchanged zeolites such as SM3; hydrotalcites, various similar compounds, and the like.

The above-mentioned hydrotalcite has the following formula: [M _1-x ²⁺ M _x ³⁺ (OH) ₂ ] ^{x +} [A _{x / n} ⁿ -mH ₂
O] ^x- (in the formula, M ²⁺ represents a divalent metal, M ³⁺ represents a trivalent metal, A ^n- represents an n-valent anion, and x represents 0 to 0.33). Two
Examples of the valent metal include Mg ²⁺ , Zn ²⁺ , Ni ^{2+ and the} like, trivalent metals such as Al ³⁺ , Fe ³⁺ and Cr ³⁺ , and examples of the n-valent anion include Cl ⁻ and NO ₃ ^−. , CO ₃ ²⁻ , salicylic acid, oxalic acid, citric acid and the like can be exemplified. The hydrotalcite-like compound does not satisfy the range of x in the above formula, for example, [Mg ₂ Al ₂ (OH) ₈ ] ⁺ [(CO ₃ ).
mH ₂ O] ^- it is true. Of these hydrotalcites and their similar compounds, the Mg-Al-CO ₃ system and the Mg-Al-Cl system are the most typical and easily available.

The amount of the above basic solid catalyst used is usually 0.5 to 25 with respect to the aromatic-containing ketones which are the raw materials.
It is about wt%, preferably 1 to 15 wt%. 0.5
If it is less than wt%, a sufficient reaction rate cannot be obtained because the catalytic effect is low. If it exceeds 25% by weight,
There are disadvantages in terms of catalyst cost and catalyst separation work.

Except for hydrotalcites, the basic solid catalysts described above usually have a basic point of 4 or less because gases such as oxygen and nitrogen are easily adsorbed and desorbed.
It is preferable to treat at a high temperature of 00 ° C. or higher to develop a basic point before use. Hydrotalcites are most preferable because they exhibit sufficient catalytic activity regardless of such high temperature treatment.

In the production method of the present invention, it is not always necessary to carry out the reaction in the presence of a solvent, but it is preferable to carry out the following solvent system from the viewpoint of the yield of the ester compound containing an aromatic compound. As the solvent, at least one selected from alkyl nitrites, alkyl halides, carbon halides, inert ketones other than the above-mentioned starting ketones, esters and aromatic hydrocarbons can be used.

Among the above-mentioned solvents, examples of alkyl nitriles include various known ones such as acetonitrile, propionnitrile, butyl nitrile, etc. Among them, acetonitrile is preferable. Known alkyl halides can be used, but those having about 1 to 5 carbon atoms are preferable, and dichloromethane, trichloromethane, dichloroethane, trichloroethane, dichloropropane, dichlorobutane, trichloropropane, trichlorobutane,
Examples include tetrachloropropane and tetrachlorobutane. Examples of the halogenated carbon include carbon tetrachloride, hexachloroethane, octachloropropane and the like. As the ketones, inert ketones that do not participate in the liquid phase oxidation of the present invention correspond, and examples thereof include acetone, methyl ethyl ketone, methyl isobutyl ketone, diethyl ketone, dibutyl ketone and the like. Examples of the esters include methyl acetate, ethyl acetate, isobutyl acetate, methyl propionate, ethyl propionate, isobutyl propionate and the like, and aromatic hydrocarbons include benzene, toluene, xylene, ethylbenzene, isobutylbenzene and tetralin. Etc. can be illustrated. Any of the above solvents may be used alone or in combination of two or more. Among the above solvents, alkyl halides are preferable, and dichloroethane is particularly preferable, from the viewpoint of yield of esters containing an aromatic compound.

The amounts of the acyclic ketones having an aromatic group, the aldehydes and the optionally used solvent may be appropriately determined according to the kind of the ketone. Usually, the amount of aldehyde is 1 part by mole or more, preferably 1 to 50 parts by mole, relative to 1 part by mole of the ketone. When the amount of aldehydes is less than 1 part by mole, the reaction is difficult to proceed sufficiently. The amount of the solvent used is usually 1 part by weight or more with respect to 1 part by weight of aldehydes,
It is preferably 2 to 125 parts by weight. If the amount of solvent used is less than 1 part by weight, the reaction rate will decrease.

In the production method of the present invention, a predetermined amount of aldehydes is dissolved in the solvent, the aldehydes are autoxidized in an oxygen atmosphere to generate peroxides, and then the starting ketones are collected. A two-step method in which a predetermined amount of raw material ketones is esterified at the same time as the generation of a peroxide as an intermediate can be employed. The one-step method is preferable in terms of reaction efficiency.

In the production method of the present invention, there is no particular limitation on the method for forming an oxygen atmosphere. For example, if an oxygen stream is supplied to the gas phase of the reaction system or oxygen is bubbled directly into the liquid phase, the oxygen atmosphere can be easily obtained. Can be prepared. Oxygen supply is
It must be carefully determined because it correlates with the amount of peracid generated in the reaction system. Normally, the supply amount of the reaction solution per unit volume per unit time is 0.1 to 1200 liters hr ^-1 liters.
⁻¹ , preferably 25 to 200 liters · hr ⁻¹ · liter ⁻¹ .

The production method of the present invention is characterized in that the target ester compound can be obtained at a normal pressure and a high yield by employing the above-mentioned specific catalyst, but it does not exclude the pressurizing condition. Absent. The reaction temperature is preferably such that the peracid generated from the aldehydes is not decomposed, usually about 5 to 65 ° C, more preferably 30 to 50 ° C.
℃. If the temperature exceeds 65 ° C, the yield of the ester containing aromatic tends to decrease. When a solvent is used and the reaction is carried out at normal pressure, it is preferable that the temperature is within the above temperature range and below the boiling point of the solvent. The reaction time varies depending on the kind of the starting ketones and the reaction temperature, but is usually about 2 to 10 hours.

[0019]

EFFECTS OF THE INVENTION According to the present invention, acyclic esters having an aromatic group can be produced in a high yield of about 50 to 100% under mild conditions. In addition, since the present invention uses a solid base catalyst, it has effects such as no toxicity and easy separation and disposal of the catalyst.

[0020]

The present invention will be described in more detail with reference to the following examples and comparative examples, but the present invention is not limited to these examples.

Example 1 A 100 ml _three- necked flask equipped with a reflux tube was charged with 15 ml of dichloroethane as a solvent and hydrotalcite ([Mg ₁₀ Al ₂ (OH) ₂₄ ] ⁺ [(CO ₃ ) .mH) as a catalyst.
₂ O)] ^- ) 0.025 g and benzaldehyde 1.22 ml as an aldehyde compound are added and heated to 40 ° C., and then oxygen is supplied at a rate of 45 to 55 ml / min to 30%.
Bubbling for a minute. Then, dichloroethane 5 in advance
A solution in which 0.628 g (4.18 mmol) of p-methoxyacetophenone as a raw material ketone was dissolved in ml was used.
The mixture was added dropwise over 10 minutes, and further reacted for 4 hours and 20 minutes to obtain an ester as a target product. Analysis of the ester containing the aromatic was carried out by gas chromatography. Conversion rate,
The selectivity is shown in Table 1. The selectivity refers to the ratio of the target product in the converted raw materials.

Examples 2 to 18 and Comparative Examples 1 to 3 The same procedure as in Example 1 was carried out except that at least one of raw material ketones, reaction time, catalyst and solvent was changed as shown in Table 1. Table 1 shows the conversion rate and the selectivity.

[0023]

[Table 1]

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) C07C 67/42 C07C 69/157 C07C 69/76 C07D 213/803

Claims (4)

(57) [Claims] 1. A method for producing an acyclic ester having an aromatic group by liquid phase oxidation of an acyclic ketone having an aromatic group in the presence of a catalyst, aldehydes and oxygen, wherein the catalyst is a solid base. A method for producing an acyclic ester having an aromatic group characterized by being a catalyst. 2. The method according to claim 1, wherein the solid base catalyst is hydrotalcites. 3. An organic solvent is present in the reaction system.
Or the production method described in 2. 4. The organic solvent is at least one selected from alkyl nitriles, alkyl halides, carbon halides, inert ketones other than the above-mentioned aromatic-containing ketones, esters and aromatic hydrocarbons. The manufacturing method according to claim 3.