JPH0159257B2 - - Google Patents

Description

[Detailed description of the invention]

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a combination of palladium or a compound of palladium, a compound of chromium, and Zn in a liquid phase of a mixture of an aromatic hydrocarbon, molecular oxygen, a carboxylic acid, and optionally a hydrocarbon solvent. , benzene, naphthalene, anthracene, biphenyl, phenanthrene, fluorene, terphenyl, etc., in the presence of a catalyst consisting of a compound of at least one metal selected from the group consisting of , Mn, Sn, Co, and Ni. An improved method for producing aryl esters from aromatic hydrocarbons is provided. Description of the Prior Art The production of phenols by direct oxidation of benzene with oxygen is known. For example, there are thermal methods that are carried out at very high temperatures;
As described in U.S. Patent No. 2,223,383,
Significant yield losses occur as the phenols produced are more susceptible to oxidation. In the presence of a catalyst, oxidation can be carried out at somewhat lower temperatures as in U.S. Pat. No. 3,133,122, but as in U.S. Pat.
2,392,875, the reaction was inhibited by low conversion and excessive formation of undesirable by-products. Chem ． and Ind. , March 12, 1966, p. 457, in the presence of palladium acetate in the liquid phase,
It has been proposed to produce phenyl acetate and biphenyl acetate from benzene and acetic acid by a stoichiometric reaction without addition of molecular oxygen. U.S. Pat. No. 3,542,852 describes the formation of hydroxyaromatic compounds by 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. Manufacture is listed. More recently, group metals (U.S. Pat. No. 3,642,873) or compounds of such metals (U.S. Pat. No. 3,651,127)
The preparation of phenyl esters and phenols by the reaction of benzene, molecular oxygen, and lower aliphatic carboxylic acids in the presence of a catalyst consisting of Similarly, variations of this type of reaction are described in U.S. Pat.
It is described in No. 3959352 and No. 3959354. 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. U.S. Patent No. 3,772,383
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. is described. U.S. Pat. No. 3,644,486 describes the oxacylation product of a fused aromatic compound, a saturated aliphatic or cycloaliphatic carboxylic acid, and molecular oxygen in the presence of a noble metal of a group of the Mendeleev periodic table or a compound thereof. and optionally catalytic preparation of hydroxylated products. The patent also states that transition metals can be used with group metals and that carbonates or acylates of alkali metals or alkaline earth metals can also be used as activators in the catalyst system. ing. However, it has been shown that the yield of hydroxylated products is very low. Generally speaking, these prior art methods:
Mostly gas phase oxidation reactions or liquid phase reactions where all reactants (other than oxygen in some cases) are initially included in the reaction mixture and using lower alkyl carboxylic acids such as acetic acid and propionic acid . 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 phenols or naphthols 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 that the present invention is based on the use of a catalyst system comprising a compound of palladium, a compound of chromium, and a compound of at least one metal selected from the group consisting of Zn, Mn, Sn, Co, Ni. , benzene, naphthalene, anthracene, biphenyl, phenanthrene, terphenyl, fluorene, etc., with molecular oxygen and higher carboxylic acids to form the corresponding aromatic carboxylic acid esters with good conversion and desired products. An improved oxidation method was discovered for the conversion to with good selectivity. The method of the invention is particularly suitable for aromatic hydrocarbons such as naphthalene, anthracene, biphenyl, phenanthrene, terphenyl, fluorene, etc.
Solvents for aromatic hydrocarbons can also be used when they contain more than one carbon atom and two or more aromatic rings. 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 invention may be used alone or supported on a carrier or support material. 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 formulas R
(COOH) _o (where n is an integer from 1 to 5, R
is a hydrocarbon group having at least 5-n carbon atoms), mono- and polycarboxylic acids having from 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, in the reaction,
A small amount of carboxylic acid anhydride may be included along with the carboxylic acid. Organic solvents for higher aromatic hydrocarbons that may be useful for entrainment and removal of water from the reaction mixture include those with the formula CnH _2o-2 (where n is 4) such as heptane, pentane, octane, etc. ~14)
linear hydrocarbons having the formula _CnH2o , where n is from 4 to 14, linear and cycloaliphatic ethers. The method of the present invention uses 10
95% conversion rate of carboxylic acid to ester
The selectivity to phenyl ester occurs at a certain degree. 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 reacted in an oxygen-containing atmosphere at about 100%
at a reaction temperature ranging from ~300°C, preferably from about 140 to 200°C, from about 1 to 100 atmospheres, preferably from 1 to 200°C.
10 atmospheres, most preferably at or near normal pressure,
Contact with catalyst. 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) is 1.0:0.1:0.1~
In the range of 1:20:20, preferably from 1:0.2:0.2
Must be in the range 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, and 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 a long period 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 detrimental 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. Example 1 0.67 g in a 250 ml three-necked flask equipped with a mechanical stirrer, reflux condenser, and Dean-Stark tube.
(0.003 mol) of palladium acetate () and 0.66 g
(0.003 mol) of zinc acetate, 0.74 g (0.003 mol) of chromium acetate () monohydrate, 39.81 g (0.276 mol) of octanoic acid, and 4.09 g (0.051 mol) of benzene were charged. Stir the resulting mixture
It was heated to 170° C. and oxygen was bubbled through the reaction mixture at a flow rate of about 50 c.c./min. During the reaction, water was produced and was continuously removed by azeotropic distillation with excess benzene as it was produced. During the reaction process,
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 mol). After 5 hours of reaction time, GLC analysis of the reaction mixture revealed phenyl octoate (19 mmol) and a small amount of phenyl ester for a total of 26.8 mmol of phenyl ester (approximately 10% conversion of octanoic acid). It showed the formation of bisoctanoyloxyesters (o, m, p-mixture) (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. show. The method described in Example 1 was followed.
However, the catalyst is 0.67g of palladium acetate ()
(0.003 mol) and 0.74 g of chromium acetate (). of the reaction mixture after 5 hours of reaction time.
GLC analysis showed that only 5 mmol of octanoic acid phenyl ester (2% conversion) was formed. Examples 2-5 The procedure of Example 1 was repeated. However, instead of 0.003 mol of zinc acetate (), the same amount (0.003 mol) of acetate as shown in the following table was used as part of the catalyst system. The amount of phenyl ester for 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 table below.

【table】
4 Co 20 6.6

5 Ni 17.5 5.8

Claims (1)

[Claims] 1. A reaction mixture of an aromatic hydrocarbon, a carboxylic acid, and molecular oxygen is mixed with palladium or a palladium compound and a chromium compound in a liquid phase at a temperature in the range of 100° to 300°C. An oxidation method for producing an aryl ester comprising contacting with a catalyst comprising at least one member selected from the group consisting of zinc, manganese, tin, cobalt and nickel. 2. The method according to claim 1, wherein the aromatic compound is selected from the group consisting of benzene, naphthalene, anthracene, biphenyl, phenanthrene, fluorene, and terphenyl. 3 Carboxylic acid has the formula R(COOH) _o (in the above formula, n
is an integer from 1 to 5 and R is a hydrocarbon group having at least 5-n carbon atoms. 4 n is 1 and R is an aliphatic hydrocarbon group having 7 to 11 carbon atoms, Claim 3
The method described in section. 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.