JPS61200944A - Manufacture of aryl ester - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to the production of palladium or palladium in a liquid phase of a mixture of an aromatic hydrocarbon, molecular oxygen, a carboxylic acid, and optionally a hydrocarbon solvent. benzene, naphthalene,
An improved method for preparing aryl esters from aromatic hydrocarbons such as anthracene, biphenyl, phenanthrene, fluorene, terphenyl, etc. is provided.

Description of the Prior Art The production of phenol by direct oxidation of benzene with oxygen is known. For example, there are thermal methods that are carried out at very high temperatures, but in this method U.S. Pat.
．． As described in No. 383, considerable yield losses occur because the phenol produced is more susceptible to oxidation. In the presence of a catalyst, U.S. Patent No. 3.133.
Although the oxidation can be carried out at somewhat lower temperatures, as in U.S. Pat. reaction was inhibited.

457, March 12, 1966, describes the stoichiometric reaction of benzene and acetic acid in the liquid phase in the presence of palladium acetate without the addition of molecular oxygen. The production of phenyl acetate and biphenyl from

U.S. Pat. No. 3,542,852 describes the reaction of aromatic compounds with oxygen in the presence of nitrate ions and carboxylic acids in the presence of a catalyst consisting of iron or a noble metal or any compound. The production of aromatic compounds is described. More recently, research has been conducted on the relationship between benzene and molecular oxygen in the presence of a catalyst consisting of a Group I metal (U.S. Pat. No. 3,642,873) or a compound of such a metal (U.S. Pat. No. 3,651,127). The production of phenyl esters and phenols by reaction with lower aliphatic carboxylic acids is described. Similarly, variations on this type of reaction are described in U.S. Pat.
．． No. 101, No. 3.772.383, No. 3.95
No. 9.352, No. 3.959.354. US Pat. No. 3,959,354 concludes that this type of liquid phase reaction is disadvantageous for industrial processes due to problems such as catalyst elution.

US Pat. No. 3,772,383 describes a liquid phase reaction using a highly complex catalyst system involving the use of nitric acid and lower aliphatic carboxylic acids such as acetic acid, propionic acid, butyric acid, etc. U.S. Pat. No. 3,644,486 discloses an oxaacyl compound of a fused aromatic compound, a saturated aliphatic or cycloaliphatic carboxylic acid, and molecular oxygen in the presence of a noble metal of Group I of the Mendeleev periodic table or a compound thereof. oxidation (oxa)
cylation) and optionally hydroxylated products. This patent also states that transition metals can be used in conjunction with Group I metals and that carbonates or acylates of alkali metals or alkaline earth metals can also be used as activators in the catalyst system. are doing. However, it has been shown that the yield of hydroxylated products is very low.

Generally speaking, these prior art methods are mostly gas phase oxidation reactions, or in which all reactants (other than oxygen in some cases) are initially included in the reaction mixture and acetic acid and propionic acid It deals with liquid phase reactions using lower alkyl carboxylic acids such as. Moreover, prior art catalytic processes generally give low conversions, usually less than 10%, have poor selectivity to the desired aryl ester, and hydroxyaromatic compounds such as phenol or naphthol are often the main products. be. The use of lower saturated carboxylic acids, primarily acetic acid, in catalytic oxidation processes creates a highly corrosive system that can result in reactor corrosion problems and excessive recycle costs and the very low conversions and selectivities mentioned above. There is sex. No prior art process describes the continuous addition of aromatic hydrocarbons and the continuous removal of water as they form from the reaction mixture, and no prior art process describes the continuous addition of aromatic hydrocarbons and the continuous removal of water as they form from the reaction mixture, nor the Nothing describes or suggests the use of solvents or catalysts of the invention for.

SUMMARY OF THE INVENTION The present inventors have disclosed a catalyst system comprising the use of a catalyst system consisting of a compound of palladium, a compound of chromium and a compound of at least one metal selected from the group consisting of 2n, Mn, Sn, Co, Ni. , benzene, naphthalene, anthracene, biphenyl, phenanthrene, terphenyl,
Improvements for the conversion of aromatic hydrocarbons, such as fluorene, with molecular oxygen and higher carboxylic acids to the corresponding aromatic carboxylic acid esters with good conversion and good selectivity to the desired products. discovered a method of oxidation. The method of the present invention is particularly useful when the aromatic hydrocarbon contains 10 or more carbon atoms and 2 or more aromatic grooves per molecule, such as naphthalene, anthracene, biphenyl, phenanthrene, terphenyl, fluorene, etc. , solvents for aromatic hydrocarbons can also be used. A preferred method of the invention uses mono- or polycarboxylic acids having 5 or more carbon atoms.

The liquid phase reaction of the present invention produces good yields of aryl esters. In particular, good yields of aryl esters are produced when the water produced when aromatic hydrocarbons are converted to esters is continuously removed in the process. If water, a by-product of the acetylation reaction, is left in the reaction mixture, it can hydrolyze the aryl ester to form aromatic hydroxyl compounds, which in turn can act as catalysts. May cause fouling and deactivation.

Catalysts useful in the process of the invention preferably include metallic palladium or a compound of palladium, usually conveniently palladium carbonate, together with a chromium compound and a compound of at least one metal selected from the group consisting of zinc, manganese, tin, cobalt, nickel. Consists of acid salts. The catalyst of the present invention may be used alone or supported on a carrier or support. Suitable supports include silica, alumina, carbon, quartz, pumice, diatomaceous earth, etc., and other supports known in the art.

Carboxylic acids useful in the present invention include formula R ([:00)1)
, (where n is an integer from 1 to 5 and R is at least 5
- is a hydrocarbon group having n carbon atoms), mono- and polycarboxylic acids having 5 to 30 carbon atoms are included. Most preferred are monocarboxylic acids in which n is 1 and R is an aliphatic hydrocarbon group having 7 to 19 carbon atoms. If desired, a small amount of carboxylic acid anhydride may be included along with the carboxylic acid in the reaction.

Organic solvents for higher aromatic hydrocarbons that may be useful for entrainment and removal of water from the reaction mixture include those of the formula CnLh, such as heptane, pentane, octane, and the like.

2 (where n is from 4 to 14), cyclic hydrocarbons having the formula CnLn (where n is from 4 to 14), linear and cycloaliphatic ethers. included.

For the benzene reactant, the process of the present invention produces conversions of carboxylic acids to esters on the order of 10% with selectivities to phenyl esters on the order of 95%. The phenyl ester produced by the method of the present invention can be easily converted into the corresponding phenol and the corresponding carboxylic acid by known hydrolysis methods. The phenol is easily recovered by known methods and the corresponding carboxylic acid is easily recycled for further use in the oxidation reaction of the present invention.

DESCRIPTION OF PREFERRED EMBODIMENTS In a typical reaction according to the present invention, benzene and a carboxylic acid are heated in an oxygen-containing atmosphere at about 100-300°C.
Contact with the catalyst is preferably carried out at a reaction temperature in the range of about 140 to 200°C, at about 1 to 100 atmospheres, preferably 1 to 10 atmospheres, most preferably at or near atmospheric pressure.

Molecular oxygen may be oxygen itself or any mixture of gases containing molecular oxygen. For example, molecular oxygen may conveniently be in the form of air. The catalyst may be in the form of a mixture of palladium acetate, chromium acetate and at least one of zinc acetate, manganese acetate, tin acetate, cobalt acetate, nickel acetate. The molar ratio of Pd:Cr:M (where M is a member selected from the group consisting of zinc, manganese, tin, cobalt, and nickel color) is 1.0: 0.1: 0.1
~1:20:20, preferably l:0.
2: Must be in the range of 0.2 to 1:10:10. During the reaction, the water produced as a by-product is conveniently continuously removed by entrainment with excess benzene or, if an organic solvent is used, with the organic solvent. As the reaction progresses, benzene or organic solvent is continuously distilled from the reaction mixture. The main product, phenyl carboxylate, can be hydrolyzed to phenol,
The carboxylic acid and catalyst can be sent back by recycling for reuse in the oxidation reaction of the present invention.

Since essentially no phenol is produced directly in the oxidation reaction of the present invention, it is believed that the catalyst remains active for long periods of time under continuous use. The rapid removal of water from the reaction mixture is probably at least one cause of the absence of phenol in the oxidation reaction product. The presence of phenol in the oxidation reaction mixture appears to be deleterious in that it fouls and deactivates the catalyst, greatly shortening catalyst life. The method of the present invention will be further explained below using Examples and Comparative Examples.

0.67 g (
0,003 mol) of palladium(II) acetate and 0.66
g (0,003 mol) of zinc acetate and 0.74 g (0
,003 mol) of chromium acetate (■) monohydrate and 39.8
1 g (0,276 mol) of octanoic acid and 4.09
g (0,051 mol) of benzene. The resulting mixture was stirred and heated to 170° C., and oxygen was bubbled into the reaction mixture at a flow rate of about 500 C/min.

During the reaction, water was produced and was continuously removed by azeotropic distillation with excess benzene as it was produced. During the course of the reaction, the reaction temperature was maintained at 170°C±2°C and additional benzene was pumped into the reactor at a slow rate. The reaction was carried out for 5 hours, and the total amount of benzene was 17.5 g (0,255
mole). After a reaction time of 5 hours, G of the reaction mixture
LC analysis revealed that a small amount of phenylenebisoctanoyloxyester (o, m, p-mix)
(3.9 mmol in total).

Comparative Example 1 This example shows that a catalyst consisting only of a palladium compound and a chromium compound is inferior to a catalyst consisting of a palladium compound, a chromium compound, and a compound of one member from the group consisting of zinc, manganese, tin, cobalt, and nickel. shows. The method described in Example 1 was followed.

However, the catalyst was 0.67 g of palladium(II) acetate.
(0,003 mol) and 0.74 g of chromium(II) acetate
It consisted of I). GLC analysis of the reaction mixture after a reaction time of 5 hours showed that only 5 mmol of octanoic acid phenyl ester (2% conversion) was produced.

Examples 2-5 The procedure of Example 1 was repeated. However, instead of 0.003 mol of zinc acetate (I[), the same amount (0,0
0.3 mol) of acetate was used as part of the catalyst system. The phenyl ester content of each sample and the number of moles of phenyl ester per mole of palladium (after 5 hours of reaction time) are also shown in the following table.

dispatch

Claims (12)

[Claims] (1) A reaction mixture of an aromatic hydrocarbon, a carboxylic acid, and molecular oxygen is mixed with palladium or a palladium compound, a chromium compound, zinc, manganese, An oxidation method for producing an aryl ester comprising contacting with a catalyst comprising at least one member selected from the group consisting of tin, cobalt and nickel. (2) Claim No. 1 in which the aromatic compound is selected from the group consisting of benzene, naphthalene, anthracene, biphenyl, phenanthrene, fluorene, and terphenyl.
) Method described in section. (3) The carboxylic acid has the formula R(COOH)_n (in the above formula,
2. A process according to claim 2, wherein n is an integer from 1 to 5 and R is a hydrocarbon group having at least 5-n carbon atoms. (4) The method according to claim (3), wherein n is 1 and R is an aliphatic hydrocarbon group having 7 to 11 carbon atoms. (5) The method according to claim (4), wherein water produced in the oxidation reaction is continuously removed from the reaction mixture. (6) The method according to claim (5), wherein the aromatic hydrocarbon is benzene. (7) The method according to claim (6), wherein the carboxylic acid is octanoic acid. (8) The method according to claim (7), wherein the catalyst comprises a palladium carboxylate, a chromium carboxylate, and a zinc carboxylate. (9) The method according to claim (7), wherein the catalyst comprises a palladium carboxylate, a chromium carboxylate, and a tin carboxylate. (10) The method according to claim (7), wherein the catalyst comprises a palladium carboxylate, a chromium carboxylate, and a manganese carboxylate. (11) The method according to claim (7), wherein the catalyst comprises a palladium carboxylate, a chromium carboxylate, and a cobalt carboxylate. (12) The method according to claim (7), wherein the catalyst comprises a palladium carboxylate, a chromium carboxylate, and a nickel carboxylate.