JPS63174950A - Production of aromatic ester - Google Patents

Abstract

PURPOSE:To obtain the titled compound in high yield, in high selectivity and stably, by adding a bismuth compound soluble in a system and/or a lead compound to a reaction system and oxidizing benzene (derivative) with O2 in the presence of an aliphatic carboxylic acid by the use of a solid catalyst in a liquid phase. CONSTITUTION:In oxidizing benzene or a benzene derivative shown by formula I (R1 and R2 are H, 1-4C alkane or 2-4C alkene) with oxygen or an oxygen- containing gas in a liquid phase in the presence of an aliphatic carboxylic acid shown by formula II (R3 is H or 1-6C alkane) by the use of a solid catalyst, a compound (preferably a catalyst obtained by supporting palladium and bismuth or lead on a carrier) shown by formula III (X is Bi and/or Pb) and a bismuth compound or a lead compound (e.g. bismuth oxide, lead chloride, etc.) soluble in the reaction system are added to the reaction system and esterification reaction is oxidatively performed. Stability of the catalyst is extremely improved. The titled compound is useful as a perfume component, solvent, phenolic precursor, benzyl alcohol precursor, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing aromatic esters by liquid phase oxidation of benzene or benzene derivatives. More specifically, when benzene or benzene derivatives are oxidized in the liquid phase with oxygen or oxygen-containing gas using a solid catalyst in the presence of an aliphatic carboxylic acid, system-soluble bismuth compounds and/or
Alternatively, the present invention relates to a novel method for producing an aromatic ester by coexisting a lead compound in a reaction system.

[Prior Art] Aromatic esters, such as phenylacetate and benzyl acetate, are useful in themselves as various fragrance ingredients and as solvents for alkyd resins and cellulose resins.

Phenyl acetate can be hydrolyzed with alkali or acid to give phenol and is a useful precursor of phenol.

In addition, benzyl acetate can be easily hydrolyzed with alkali or acid to give benzyl alcohol, and this benzyl alcohol is used as a volatilization retaining agent for fragrances, a color development aid for photographs, a glossing agent for resins and paints, and in various chemicals. It is also widely used as a raw material for the synthesis of products.

In the case of xylylene diacetate, xylylene glycol is also obtained by hydrolysis. This aromatic alcohol is useful as a raw material for synthetic fibers, synthetic resins, plasticizers, polyurethane, composite materials with carbon fibers, etc., and especially as a raw material for producing heat-resistant polymeric substances. Not only are aromatic esters themselves industrially useful, but their hydrolysis products, aromatic alcohols, are also useful compounds.

Conventionally, in the reaction to obtain methylbenzene carbonyl by oxidizing methylbenzene in the presence of an aliphatic carboxylic acid,
Palladium is known to be an effective catalyst. For example, The Journal of Organic Chemistry (J.

Orq. Chem. >, (34) 4.1106 ~ 11
0B (1969) reports a method for synthesizing xylylene diacetate by air oxidizing xylene in acetic acid using palladium acetate as a catalyst. However, since this method uses a homogeneous catalyst, there are problems in separation and recovery of expensive palladium, and it cannot be called an industrial production method.

In addition, J
3, methods using various supported catalysts have also been reported for the purpose of facilitating the recovery and regeneration of palladium.

For example, Japanese Patent Publication No. 50-28945 discloses a method using palladium supported on activated carbon,
No. 8232 discloses a method using a catalyst supporting a carboxylate of a metal selected from the group consisting of palladium-antimony, alkali metals, alkaline earth metals, zinc, cadmium, and lead, JP-A-53-147039. JP-A-53-79832 discloses the use of catalysts containing palladium, arsenic, alkali metals or alkaline earth metals; JP-A-53-79832 discloses the use of palladium, bismuth and manganese or chromium-based catalysts; JP-A-57-102840 discloses the use of catalysts containing palladium, arsenic, alkali metals or alkaline earth metals; discloses a catalyst in which two or more of palladium, an alkali metal compound, and a cobalt, nickel, or tin compound are supported on activated carbon, each of which has improved catalyst activity and life.

When aromatic esters are synthesized using such a supported solid catalyst, what is important from an industrial perspective is that the catalyst has high activity and selectivity, as well as high stability. The stability of the catalyst used is important when carrying out either the gas phase method or the liquid phase method. In the case of liquid phase reaction,
Catalytic active components such as palladium tend to be leached out during the reaction, so the catalyst activity decreases over time and may even become deactivated. Regarding the liquid phase method, there is currently no effective method for preventing the elution of active catalyst components, and a technical solution is desired.

[Problems to be Solved by the Invention] The present invention aims to solve the above-mentioned problems by esterifying benzene or benzene derivatives with molecular oxygen using a solid catalyst in the presence of an aliphatic carboxylic acid. By doing so, with higher yield and selectivity than conventionally known methods,
And stably produce aromatic esters from benzene or benzene derivatives! The purpose is to provide a method for J-building.

[Means for Solving the Problems] The object of the present invention is to provide a method according to the present invention, wherein R1 and R2 are H, C, -4 alkane groups, or C alkene groups 2-4. show. ] and general formula % formula % [In the formula, R3 represents H or an alkane group of 01 to 6, or H in the group is substituted with C4). ] [In the reaction of oxidizing both compounds represented by [or oxygen-containing gas], Pd-X (in the formula, X represents 3i and/or Pb) and a system-soluble compound of the X are present in the reaction system. This is achieved by a method for producing an aromatic ester characterized by the following.

[Effect 1] As the catalyst used in the oxidative esterification reaction of the present invention, a catalyst in which palladium and bismuth or lead are supported on a carrier is suitable.

A catalyst supporting at least one promoter metal selected from the group consisting of copper, silver and gold or at least one promoter metal selected from the group Nb of the periodic table excluding mercury as a third component. It is valid. Any catalyst carrier can be selected, such as activated carbon, silica gel, silica/alumina, viscosity, bauxite, magnesia, diatomaceous earth, pumice, etc., but S + 02 is particularly excellent in the catalyst composition of the present invention. ing.

m of the metal component in the catalyst is usually palladium 0.1-20E
aff1%, bismuth or lead 0.01 to 30w%. The atomic ratio of bismuth or lead to palladium in the catalyst is selected in the range from 0.1 to 10. Furthermore, when adding a promoter metal as a third component,
The concentration is selected from the range of 0.01 to 30% by weight.

In the case of the palladium and bismuth or lead catalysts used in the present invention, both catalyst components are believed to be present in the metallic state on the support. In addition, from the perspective of the manufacturing method, palladium and bismuth, and palladium and lead form alloy-like complexes, and some palladium exists in the form of palladium hydride (for example, Pd/H). ,7.

However, complexes of palladium and bismuth or lead are not stable in reaction media containing aliphatic carboxylic acids, and as the oxidative esterification reaction progresses, bismuth or lead dissolves and is eluted into the medium. . For example, when acetic acid is used as the aliphatic carboxylic acid, it is thought that it will be eluted in the form of bismuth acetate or lead acetate. Furthermore, it is presumed that molecular oxygen present in the reaction system is also involved before and after bismuth or lead is converted into acetate.

In this way, when the bismuth or lead component constituting the catalytically active species is eluted, palladium, which is the main active species, is eluted in parallel, resulting in a decrease in catalytic activity and deactivation.

Therefore, if it is possible to suppress excessive elution of bismuth or lead into the reaction medium in a palladium- or lead-based catalyst, it is thought that elution of palladium can also be prevented and stable use of the catalyst will become possible.

In the method of the present invention, the stability of the catalyst can be dramatically improved by adding a soluble bismuth compound or a soluble lead compound to the reaction system and carrying out the oxidative esterification reaction. As a system soluble bismuth compound to be added,
Bismuth oxide, bismuth hydroxide, bismuth chloride, bismuth chloride, bismuth nitrate, bismutyl nitrate, basic bismuth carbonate, bismuth acetate, etc. Examples of soluble lead compounds include lead oxide, lead hydroxide, lead chloride, lead carbonate, basic Compounds with relatively high solubility in aliphatic carboxylic acids, such as lead carbonate and lead acetate, are preferably used.

Furthermore, metal bismuth and metal lead can also be used if necessary. Among the soluble bismuth or lead compounds, it is particularly preferable to add a bismuth or lead compound corresponding to the aliphatic carboxylic acid used in the oxidative esterification reaction.

The concentration of soluble bismuth or lead salt used in the reaction is selected in the range of 0.01 to 10% by weight in 3i or pbcJ degrees.

The soluble bismuth or lead compound added to the reaction system is recovered in a dissolved form in the product solution, and known methods are applied for separation and purification.

That is, when acetic acid is used as the aliphatic carboxylic acid,
Bismuth or lead acetate has low solubility in aromatic esters, so it can be recovered as crystals in the aromatic ester recovery and production process, and can be easily separated and recovered by normal filtration operations. . In addition, the recovered bismuth or lead acetate can be reused in the reaction as it is or after further purification.

The present invention performs liquid phase oxidation in aliphatic carboxylic acids, but aliphatic carboxylic acids are used in view of oxidation stability and ease of recovery and recycling of carboxylic acids when aromatic esters are hydrolyzed. Acetic acid is preferred, and in addition, formic acid,
Propionic acid, butyric acid, iso1li311i? , valeric acid,
Unsubstituted aliphatic monocarboxylic acids such as caproic acid and substituted aliphatic monocarboxylic acids such as lower alkoxy- or chloro-substituted monocarboxylic acids such as acetoacetic acid, chloroacetic acid, and chloro-O-pionic acid may also be used. can.

The amount of aliphatic carboxylic acid to be used is not limited, but it is preferably 1 to 20 times the molar amount of benzene or benzene derivative. Since the aliphatic carboxylic acid also functions as a solvent, there is no need to add a solvent. Although there are no particular restrictions, it is preferable to use the aliphatic carboxylic acid in an anhydrous state as much as possible.

In addition, when carrying out the liquid phase oxidation of the reaction of the present invention in acetic acid,
When benzene and benzene derivatives such as toluene, ethylbenzene, and styrene are oxidized, phenylacetate,
Benzyl acetate, α-phenylethyl acetate,
β-acetoxystyrene is obtained.

Moreover, in the case of xylene, methylbenzyl acetate and xylylene diacetate are obtained, and xylylene diacetate is obtained from methylbenzyl acetate.

The oxidative esterification reaction can be carried out using any method such as a fixed bed catalyst method or a suspended catalyst method. Moreover, any of the continuous method, semi-continuous method, and batch method can be carried out.

The reaction pressure is generally from normal pressure to 30 to 9/ctJ, but preferably from 5 to 20 to 9/ctJ in consideration of deterioration of the catalyst or reduction in reaction rate due to excess oxygen.

The reaction temperature is 80-180°C, preferably 90-15
It is 0°C.

The reaction time is preferably 1 to 10 hours, although it depends on the temperature and pressure.

The molecular oxygen used in the practice of this invention need not be pure oxygen, but may be oxygen diluted with an inert gas, such as air. Continuous or consumption 1 when introducing! f
A method of replenishing i portion intermittently may also be used.

[Examples] Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to these Examples unless it departs from the gist of the present invention. Throughout this specification, all temperatures are in degrees Celsius, and parts and percentages are in degrees Celsius unless otherwise specified.

LL Bismuth nitrate (27Q) was dissolved in a 15% nitric acid aqueous solution (2001
After dissolving in 1 d, crushed silica (100°) of 0.3 to 0.5 m+Φ was immersed and evaporated to dryness on a hot bath. The dried product was calcined in an electric furnace at 500° C. for 2 hours in an air atmosphere.

Separately, add palladium chloride (8,930) to 5% hydrochloric acid (200
ate) and heated to 60 to 70°C on a hot water bath to form a homogeneous solution. After the solution was cooled to room temperature, the baked product was immersed in the solution and evaporated to dryness on a hot bath. This dried product was treated under nitrogen flow at 150°C for 2 hours, and then reduced under hydrogen flow at 200°C for 2 hours and at 400°C for 4 hours. The catalyst thus prepared had a palladium loading of 5.4% by weight.
The atomic ratio of palladium and bismuth was 1/1.11. Using this catalyst (2,5i,
A performance test was conducted in batch mode under the following conditions. Baraxylene and acetic acid were used as raw materials.

19 Kyousu encounter 1 a) Reactor; autoclave with electromagnetic stirrer contents nail o
, in, Material S IJ S 316b) Reaction temperature 2
90℃ C) Reaction pressure 10 to 9/Cl71 (however, the initial reaction air charging pressure is shown) d) Reaction time: 2 hours e) Raw material charging basin: 25- f) Raw material composition; acetic acid/baraxylene = 8 ( molar ratio) g)
Bismuth acetate concentration: 0.9% by weight (as Bi) This batch operation was repeated for the test. That is, after the reaction, the catalyst was filtered and washed, recovered, and further raw materials were added and reacted, which was repeated. The reaction results for the first and 200th repetition are as follows, and no substantial difference in activity and selectivity was observed. Furthermore, no elution of palladium was observed.

Number of repetitions: 13il 200th time - xylene conversion rate % 32.9 32.9 Selectivity% p-MBA 74.2 73.3p-X
LDA 22.3 23.2 Space-time collection fla [g/
41 cat, hrlp-MBA 145.3
143.61)-XLDA 59.2
61.4 Palladium elution level [ppm]* p-MBA: D-methylbenzyl acedate p-X
LDA: Indicates the concentration in the 2 reaction product solution in p-xylylene diacetate.

Tests were carried out in the same manner as in Example 1, except that the bismuth acetate added in Example 1 was changed to bismuth oxide.

However, the added bismuth oxide was made to be excellent, corresponding to a bismuth concentration of 0.9% by weight.

The first test result was almost the same as Example 1, and 10
There was no change in catalyst performance after repeated tests. Also, no palladium elution was observed.

I couldn't.

L failure 1 - A repeated test similar to Example 1 was conducted except that bismuth acetate was not added to the reaction raw materials.

- In the fourth test, the same reaction results as in Example 1 are obtained, but in the fourth test, palladium elutes and the palladium concentration in the reaction solution becomes 660 [ppm], so the ρ-xylene conversion rate is 10%. It became the following.

Example 3 Example 1 except that chloroauric acid was used simultaneously with bismuth nitrate
A gold-containing catalyst was prepared in exactly the same manner. The atomic ratio of palladium/bismuth/gold in the prepared catalyst is 1/1.1
It was 110.5. A test was conducted in the same manner as in Example 1 using 2.5 g of this catalyst.

1st time, conversion rate of p-xylene 37.0%, p-MBA
The space-time yields of p-XLDA and p-XLDA were 136.4 and 8, respectively.
3.4 [0/N cat, hr], p-MBA and D
- The selectivity of XLDA is 28.0. 61.9%
Met. This reaction result did not change even after 10 repetitions.
Furthermore, no elution of palladium was observed.

Example 4 A test similar to Example 1 was conducted using the same catalyst except that propionic acid was used instead of acetic acid.

In the first run, the p-xylene conversion rate was 28%, and the selectivity of benzyl paramethylpropionate and baraxylylene dipropionate was 71% and 19%, respectively.

X Lid 3J A test similar to Example 1 was conducted using the same catalyst except that toluene was used instead of p-xylene and the raw material composition was changed as follows.

Raw material composition: acetic acid/toluene-7,5 (molar ratio) Bismuth acetate concentration: 0.71% by weight (as 8i) 1st time, toluene conversion rate 35%, benzyl acetate selectivity 96.5
%, benzyl acetate space-time collection ff1205.5 [0
/j! It was cat, hrl. Even after repeating the test 20 times, the reaction results remained unchanged, and no elution of palladium was observed.

The same test as in Example 5 was conducted except that propionic acid was used instead of acetic acid. 1st time, toluene conversion rate 31%
, the selectivity for benzyl propionate was 93%.

Σ'111 A test similar to Example 1 was conducted using the same catalyst except that ethylbenzene was used instead of p-xylene.
10th, ethylbenzene conversion rate 21%, α-phenylethyl acetate selectivity 62%, α-phenylethyl acetate space-time yield [177°6 [0/jl cat, hr
It was l. Even after repeating the test 10 times, the reaction results did not change.

A test similar to that of Example 1 was conducted using styrene instead of p-xylene and the same catalyst.

1st time, styrene conversion rate 14.5%, β-acetoxystyrene selectivity 86%, β-acetoxystyrene space-time yield f
f168.3 [Q/j cat, hrl. 1
Even after repeating the test 0 times, the reaction results did not change.
Further, no elution of palladium was observed.

Example 9 A test similar to Example 1 was conducted except that benzene was used instead of p-xylene and some of the reaction conditions were changed as follows.

Reaction conditions to be changed: temperature rt 180°C, acetic acid/benzene =
5.3 (Molar ratio) The reaction results for the 1st and 10th reactions were unchanged, with a benzene conversion rate of 7.8%, phenylacetate selectivity, and space-time yield of 91% and 46.3 [g/j cat, hr, respectively].
There was lr.

A palladium-lead catalyst was prepared by conducting the same test as in Example 1, except that lead vnate (18.5 g) was used instead of bismuth nitrate.

The catalyst had a metal palladium loading rate of 5.4 ffl% and an atomic ratio of palladium to lead of 1/1.11. A test was conducted under the same reaction conditions as in Example 1 using this catalyst 2.50% and p-xylene and acetic acid as raw materials. However, the reaction raw materials contain vinegar'W instead of bismuth acetate.
I lead was added so that the lead a degree was 0.8%.

Even after repeating the reaction 1 to 20 times, the reaction results did not change: p-xylene conversion was 23.4%, p-MBA and D-XLDA (7) selectivity, and empty R yield were 5 each.
7.7 and 23.3%, 80.0 and 43.8 [0/j
It was cat, hrl.

Furthermore, no elution of palladium was observed.

! A test was conducted in the same manner as in Example 10, except that the same catalyst as in Example 10 was used and the lead compound added to the raw material was changed from lead acetate to lead oxide.

Even if the reaction was repeated 1 to 20 times, the reaction results did not change, p-xylene conversion rate was 23.2%, and ffl selectivity of p-MBA and p-XLDA. = space-time yield is 5 each
7.7 and 23.3%, 79.7 and 43.6 [0/j
! It was cat, hrl.

Furthermore, no elution of palladium was observed.

MLM2 Example 10 except that lead acetate was not added to the reaction raw material
The test was conducted in exactly the same way. , the same results as in Example 10 were obtained in the 1st to 3rd repeated tests, but 4
After the third reaction, palladium elution of 600 ppm or more was observed in the reaction solution, and the p-xylene conversion rate was 5% or less.

Example 12 A test was conducted as in Example 10 using the same catalyst, except that toluene was used instead of p-xylene.

Even when the reaction was repeated 1 to 20 times, the reaction results did not change: toluene conversion rate was 46.4%, benzyl acetate selectivity was 87.4%, and benzyl acetate space-time yield was 24%.
0 [g/J cat, hr].

Furthermore, no elution of palladium was observed.

Example 13 A test was conducted as in Example 10 using the same catalyst, except that styrene was used instead of p-xylene. 1
Even after repeating the reaction ~20 times, the reaction results remained unchanged: styrene conversion rate was 16%, β-acetoxystyrene selectivity was 82%, and β-acetoxystyrene space-time yield 1 was 77.
3 [g/jcat, hr].

Furthermore, no elution of palladium was observed.

Claims (1)

[Claims] General formula ▲ Numerical formula, chemical formula, table, etc. ▼ [In the formula, R_1 and R_2 represent H, a C_1-4 alkane group, or a C_2_-_4 alkene group. ] and general formulas ▲ Numerical formulas, chemical formulas, tables, etc. ▼ [In the formula, R_3 indicates H or an alkane group of C_1_ to_6, or H in the group is substituted with Cl. ] In the reaction of oxidizing both compounds shown in with oxygen or oxygen-containing gas, Pd-X [wherein X represents Bi and/or Pb] and a system-soluble compound of the X are present in the reaction system. A method for producing an aromatic ester, characterized by: