FI79294B - FRAMSTAELLNING AV HOEGRE ARYLESTRAR. - Google Patents

Description

1 79294

Preparation of higher aryl esters

The present invention relates to an oxidation process for the preparation of aryl esters by reacting an aromatic compound, a molecular oxygen and an aliphatic carboxylic acid with a metal compound.

Preparation of phenol by direct oxidation of benzene Hapel-la is known. For example, there are methods that are performed at very high temperatures where the phenol formed is sensitive to further oxidation so that a significant decrease in yield occurs, as disclosed in U.S. Patent 2,223,383. In the presence of catalysts, oxidation can be performed at somewhat lower temperatures, such as in U.S. Patent 3,133,122, but low conversions and excess production of unwanted by-products have been typical of reactions, as disclosed in U.S. Patent 2,392,875.

The preparation of phenylacetates and biphenyl from benzene and acetic acid in the liquid phase in the presence of palladium acetate and without the addition of molecular oxygen by stoichiometric reaction has already been proposed in Chem. and Ind., March 12, 1966, page 457.

U.S. Patent 3,542,852 discloses the preparation of oxyaromatic compounds by the reaction of an aromatic compound and oxygen in the presence of a catalyst consisting of iron, a noble 2,79294 metal, or a compound of either nitrate ion and a carboxylic acid. Still later, the preparation of phenyl esters and phenols by the reaction of benzene, molecular oxygen and a lower aliphatic carboxylic acid in the presence of a catalyst comprising a Group VIII metal (U.S. Patent 3,642,873) or a compound of such a metal (U.S. Patent 3,651,127) has been described. Accordingly, variations of this type of reaction are disclosed in U.S. Patents 3,646,111; 3,651,101; 3,772,383; 3,959,352 and 3,959,354. U.S. Patent 3,959,354 concludes that liquid phase reactions of this type are disadvantageous to the industrial process due to catalyst elution problems, etc. U.S. Patent 3,772,383 describes a liquid phase reaction using a highly complex catalyst system using nitric acid and a lower aliphatic carboxylic acid such as acetic, propionic, n-butyric, isobutyric or caproic acid. In general, these prior art methods, which mostly deal with vapor phase reactions where all reactants (except oxygen in some cases) are initially included in the reaction mixtures, use lower aliphatic carboxylic acids such as acetic and propionic acid and often require an alkali or alkaline earth metal carboxylate. More specifically, prior art catalyst processes have generally produced relatively low conversions, generally less than 10%, with poor selectivity for the desired phenyl ester, and phenol is often the primary product. The use of lower saturated carboxylic acids, especially acetic acid, in prior art processes provides a highly corrosive system, which can cause reaction equipment problems and unreasonable recycling costs, as well as low conversions and poor selectivities as mentioned above. None of the prior art processes involve the continuous addition of aromatic hydrocarbons or the continuous removal of water from the reaction mixture as it forms, nor do they disclose or suggest the use of a solvent for higher aromatic compounds in the oxidation process.

3 79294

An improved oxidation process has been invented for the conversion of higher aromatic hydrocarbons comprising 10 or more carbon atoms and two or more aromatic rings such as naphthalene, anthracene, biphenyl, phenanthrene, terphenyl and the like to a molecular oxygen and higher carboxylic acid aroma with good conversions and selectivities to the desired product by incorporating a solvent into the aromatic hydrocarbon in the process. The invention is characterized by what is stated in the characterizing part of claim 1. The invention is based on the use of mono- or polycarboxylic acids having 5 or more carbon atoms, as well as on the use of a certain type of palladium antimony catalyst in connection with the use of a solvent with a higher aromatic hydrocarbon.

It has also been found that the liquid phase reaction produces high conversions and substantial quantitative yields of higher aryl esters when the higher aromatic hydrocarbon either reacts with the carboxylic acid in the presence of an inert solvent or is continuously added as a solution in an inert solvent to the reaction mixture during the reaction and preferably continuously removed from the reaction mixture. The solvent may be one which has the ability to remove water as droplets so that the water formed, when the higher aromatic hydrocarbon is converted to the ester, is continuously removed from the reaction mixture in the process. If water, a by-product of the oxidation reaction, is allowed to remain in the reaction mixture, it can cause hydrolysis of the aryl ester to form aromatic hydroxy compounds, which in turn can cause catalyst deterioration and inactivation.

Ko. the catalysts useful in the process are preferably composed of palladium metal and palladium compounds and usually palladium carboxylate for convenience in conjunction with an anti-poly compound and usually antimony carboxylate, and alternative specific metal carboxylates may also be present. The use of significant amounts of other materials, such as those described in the prior art as catalyst accelerators, in addition to the essential palladium and antimony, and alternatively special metal compounds, in the catalyst is usually detrimental. method. The catalysts of this invention may be used alone or in conjunction with a support or supports. Suitable carriers include silica, alumina, carbon, quartz, pumice, diatomaceous earth and the like, as well as others known in the art.

Useful carboxylic acids of the invention are mono-polycarboxylic acids having 5 or more carbon atoms, corresponding to the formula R (COOH), where n is an integer of 1 n or more and R is a hydrocarbon group having at least 5 n carbon atoms. A carboxylic acid anhydride may be included in the reaction with the carboxylic acid, if necessary.

Higher organic solvents for aromatic hydrocarbons, which may also be useful for removing water from the reaction mixture, include linear hydrocarbons of formula CH wherein n is from 4 to 14 such that n is 2n + 2 for heptane, pentane, hexane, octanes, and the like, cyclic hydrocarbons. is the formula CH, where n 2n n = 4-14, and linear and cyclic aliphatic esters.

The process of this invention produces carboxylic acid conversions of about 10% or greater with naphthalene reactants as the reactant, with selectivities to naphthyl ester of about 100%. Thus, the the process produces the desired product in such significant quantities that it is immediately competitive with the best available techniques for the production of alpha- and bethanaphthyl esters and the naphthols themselves. Naphthyl esters prepared by the process of this invention can be readily converted to the corresponding naphthols and the corresponding carboxylic acid by known means by hydrolysis or pyrolysis. Naphthols can be readily recovered by known means, and the carboxylic acid, ketene, or acid anhydride is readily recyclable for use in the oxidation reaction of this invention.

In a typical reaction according to the present invention, a solution of naphtholene in heptane and a carboxylic acid is contacted with a catalyst in an oxygen-containing atmosphere at a reaction temperature of about 100 to 300 ° C, and preferably about 140 to 200 ° C, and 1 to 100, preferably 1 to 10 atmospheres most preferably at or near atmospheric pressure. The molecular oxygen may be oxygen, or a gaseous mixture containing oxygen. For example, molecular oxygen may be in the form of air for ease. The catalyst may be a mixture of (CH 2 COO) 2 D and (CH 2 COO) 2 Sb, for example in a molar ratio of about 1: 1. This Pd: Sb molar ratio can range from 1: 0.1 to 1:20 and is preferably from 1: 0.1 to 1:10. An alternative chromium, cobalt, nickel, manganese, iron or tin compound may be present in a catalytic molar ratio of 0-1-20-1 / mole of palladium and antimony in the catalyst. During the reaction, the liquid reaction mixture slowly turns dark brown and the water formed is easily removed with an organic naphthalene solvent by continuous evaporation during the process. The main product (and in most cases the only product) in the reaction, naphthyl carboxylate, far exceeds the best yields achieved in the art, mainly in quantitative selectivity. As previously mentioned, the naphthyl carboxylate thus obtained can be hydrolyzed, if desired, to produce naphthol or naphthols by known means, and the carboxylic acid and catalyst can be recycled to the oxidation reaction.

Since substantially no naphthol is produced in the process of this invention, the catalyst activity is believed to be maintained for extended periods of time in continuous use. The rapid removal of water from the reaction mixture is likely to be at least in part due to the absence of naphthol in the reaction product. The presence of naphthol in the reaction product, if it were to occur, is believed to be the cause of the catalyst deterioration and consequently the short catalyst life. The process 6 79294 of the present invention is described in more detail in the following examples.

Example I

Acetoxylation of naphthalene was performed in a glass reactor equipped with a thermometer, a mechanical stirrer,

With Dean-Stark type collector with reflux condenser and gas and liquid pipes. 43.3 g (300 mmol) of octanoic acid, 10 g (78 mmol) of naphthalene, 0.17 g (0.75 mmol) of Pd (OAc), 0.22 g (0.75 mmol) of Sb (OAc) were fed to the reactor. ) 2 and 0.17 g (0.75 mmol) of Cr (OAc). H 0 (Pd / Sb / Cr = 1: 1: 1).

3 2 To this was added 10 mmol of heptane, and the reaction mixture was stirred continuously, and the reaction temperature was maintained at about 170 ° C, and oxygen was blown through the reaction liquid at a flow rate of about 50 cm / minute. Water was formed during the reaction and was continuously removed when azeotroped with heptane. The reaction temperature was maintained at + 2 ° C + 170 ° C during the reaction. The reaction was continued in this manner for 4 hours, during which time about 1.3 moles of water were formed. GLC analysis of the reaction mixture after a reaction time of 4 hours showed that 85% of the naphthalene had been almost selectively converted (about 100%) to the naphthyl ester of octanoic acid (16.8 g; 66 mmol). Only a small amount (less than 0.3 g) of CO was prepared. The 2 moles of naphthyl ester produced per mole of palladium catalyst per hour (denoted as catalyst reversal, T.N.) was found to be 16.5. The isomer distribution (alpha versus beta) was found to be 92% (alpha-naphthyl ester) versus. 8% (beta-naphthyl ester).

Other reactions performed under identical reaction conditions replacing heptane with other hydrocarbon solvents such as octane and nonane resulted in similar results.

Example II

This reaction was carried out exactly as in the previous example except that 46.9 g (305 mmol) of octanoic acid were fed as well as 10.1 g (79 mmol) of naphthalene, 0.08 g (0.35 mmol) of Pd (OAc) 2, 0.48 g (1.6 mmol) of Sb 7 79294 (OAc) 2 and 0.09 g (0.35 mmol) of Cr (OAc) 3. IVto and 10 ml of heptane. Analysis showed that 30% of the naphthalene fed was converted to give 24 mmol of octanoic acid naphthyl ester (5.4 g) with almost 100% selective water. The T.N. of the catalyst was obtained at about 69 per 5 hours. Only small amounts of CO2 were formed.

Example III

This example was performed with a slight modification of the procedure of Example I. A solution of naphthalene was made in heptane (10% solution by weight). This was continuously fed to the reactor at a quiet rate (0.5 ml / minute). The reactor was initially charged with 41 g (284 mmol) of octanoic acid, 1.35 g (6 mmol) of Pd (OAc) 2, 1.80 g (6 mmol) of Sb (OAc) 3, 1.48 g (6 mmol) of ) Cr (OAc) 2. H 2 O and 5 mL of a naphthalene solution in heptane. The reaction was carried out at a temperature of 160- + 2 ° C, 3 and Cl 2 was produced at a rate of 50 cm / min. A solution of naphthalene in heptane was slowly pumped (0.5 ml / minute) into the reaction mixture. Excess heptane and water formed in the reaction were continuously removed, which also helped maintain the reaction temperature at 160 + 2 ° C. The reaction was thus continued for 5 hours, during which time 14.3 g (112 mmol) of naphthalene was introduced into the reactor. GLC analysis of the reaction mixture showed that in 5 hours about 82% of the derived naphthalene was converted to give an almost quantitative (about 100% selectivity) naphthyl ester (23 g; 91 mmol).

Example IV

In this experiment, a Soxhlet extraction type technique was used to introduce naphthalene into the reactor. The solid naphthalene was placed in a tank and introduced into the reactor by dissolving it *; in an inert solvent such as heptane.

In a typical experiment, 48 g (333 mmol) of octanoic acid, 1.35 g (6 mmol) of Pd (OAc) 2, 1.80 g (6 mmol) of Sb (0Ac) 3 and 1.48 g (6 mmol) of mmol) Cr (OAc) 2. H20 added. Solid naphthalene (8.2 g; 63 mmol) was placed in the tank.

β 79294 equipped with a condenser and attached to a Dean-Stark tube. 8 ml of heptane was used as an inert solvent in the reactor. The reaction mixture was stirred mechanically, and the reaction was continued at 160 ° C -2 ° C for 5 hours, during which time all the naphthalene dissolved and was introduced into the reactor by returning heptane. GLC analysis after 5 hours showed that all of the naphthalene introduced into the reactor had been converted (100% conversion) to give the naphthyl ester (15.6 g; 62.0 mmol). Only a small amount of CC 2 was formed.

Example V

This reaction was carried out exactly according to Example I, except that 48 g (333 mmol) of octanoic acid, 3.2 g (25 mmol) of naphthalene, 1.35 g (6 mmol) of Pd (OAcJ) and 1.8 g (6 mmol) of mmol) Sb (OAc) 2.

No chromium salt was used in this experiment. The reaction was carried out at 160 2 ° C for 5 hours. GLC analysis of the mixture showed that 100% naphthalene was converted to the naphthyl ester with a selectivity of about 100. The isomer distribution was found to be about 80% alpha and about 20% bethanaphthyl ester.

Example VI

This reaction was carried out exactly as in Example III except that 2.0 g (0.16 mmol) of naphthalene was introduced into the reaction and the catalyst used did not contain chromium salts.

After 5 hours of reaction, 100% naphthalene was converted to give the naphthyl ester.

Example VII

This reaction was carried out exactly as in Example V, except that Mn (OAc) 2 was also added in 3 mmol of both Pd (OAc) and Sb (OAc). There was 10 g (78 mmol) of naphthalene fed. At 170 ° C to + 5 ° C, about 20% of the naphthalene had been converted to give the naphthyl ester, with only a small amount of CCl 2 formed.

9 79294

Example VIII

This reaction was carried out in the same manner as in Example III except that glyme (ethylene glycol dimethyl ether) was used as the solvent instead of heptane, and 14.5 g of naphthalene was introduced into the reactor. Due to the water solubility of the glyme, water and glyme were continuously removed in such an amount that the reaction temperature remained at 160 + -2 ° C. GLC analysis showed that about 10% of the naphthalene had been converted to give the naphthyl ester. Almost exclusively alpha-naphthyl ester was obtained (more than 98%).

Example IX

This procedure was performed exactly as in the above example except that tetrahydrofuran was used as the solvent. After 5 hours of reaction at 160 + 2 ° C, GLC analysis showed that about 12% of the naphthalene had been converted to the naphthyl ester.

Example X

This reaction was performed exactly as in Example V except that 66 g (338 mmol) of lauric acid was used instead of octanoic acid and 10 g (78 mmol) of naphthalene were fed. The reaction was performed at 160-2 ° C for 5 hours, resulting in about 30% conversion of naphthalene to give lauric acid naphthyl ester (99% selectivity). The isomer distribution was found to be about 60% alpha and about 40% bethanaphthyl ethers.

Example XI

This reaction was performed as in Example I except that 66 g (333 mmol) of lauric acid, 10 g (78 mmol) of naphthalene, 1.35 g (6 mmol) of Pd (0Ac) 2, 1.8 g (6 mmol) of

Sb (OAc) 2 and 1.48 g (6 mmol) Cr (OAc) 3. H 2 O was used as the reaction feed. 10 ml of heptane was used as solvent.

After 5 hours of reaction at 170- + 5 ° C, 100% conversion of naphthalene was observed to give the naphthyl ester of lauric acid.

10 79294

Example XII

This experiment was performed using biphenyl as starting material instead of naphthalene. The reaction was carried out exactly as in the previous example except that 10 g (67 mmol) of biphenyl was used instead of naphthalene and 48 g (333 mmol) of octanoic acid were used instead of lauric acid. The Pd / Sb / Cr catalyst was used in half the amount of the previous example, i.e. 0.67 g (3 mmol) of Pd (OAc) 2, 0.9 g (3 mmol) of Sb (OAc) 2 and 0.75 g (6 mmol) of Cr (OAc). + 2 ° C for 5 hours, and the water formed (2 ml) was removed with heptane, GLC analysis showed that about 65% of the biphenyl was converted to give the biphenyl ester of octanoic acid, with an isomeric distribution of about 62% ortho, about 30% meta- and 8% paraphenylphenol ester.

Example XIII

A. This experiment describes the differences between reactions with or without the use of an inert solvent. Here, the reactor was fed exactly the starting materials of Example V except that 10 g of unused heptane and naphthalene were fed.

: After 5 hours of reaction, GLC analysis showed that 31% of the naphthalene reacted to give the naphthyl ester of octanoic acid: (67% selectivity) and the undesired by-product binaphthyl (3% selectivity).

B. Similarly, in the second experiment, when 1,10-decanedicarboxylic acid (64 g, 278 mmol) was used instead of octanoic acid, only 12% conversion of naphthalene occurred to give naphthyl ester (45% selectivity) and unwanted binaphthyls (55% selectivity).

C. In another experiment using octanoic acid (48 g; 333 mmol) when chromium salt 1.48 g (6 mmol) of Cr (OAc) 2 H 2 O was added in conjunction with Pd / Sb (6 mmol each), 58% in 5 hours 10 g of naphthalene were converted to give 60% selectivity for naphthyl ester and 40 l for binaphthyl.

11 79294 These experiments clearly show that in the absence of the solvent not only lower conversions were observed, but also the selectivity to the naphthyl ester deteriorated greatly, and by-products were obtained, i. binaphthyl.

Claims (8)

1. As an oxidation process for the preparation of aryl esters, reacting an aromatic compound, a molecular oxygen and an aliphatic carboxylic acid with a metal compound, characterized in that higher aryl esters are prepared from a higher aromatic hydrocarbon having 10 or more carbon atoms and two or more aromatic organic - a silicic acid of the formula R (COOH), where n is an integer of 1. n or more and R is a hydrocarbon group having at least 5 carbon atoms, and the reaction mixture of molecular oxygen is contacted in the liquid phase at a temperature between 100 and 300 ° C with a catalyst consisting of palladium or a palladium compound, an antimony compound and optionally at least one such metal compound. , which is chromium or manganese, wherein a higher aromatic hydrocarbon is continuously added to the reaction mixture, and the water formed in the process is continuously removed from the reaction mixture as an organic water-immiscible solvent when an ester is formed. Process according to Claim 1, characterized in that the higher aromatic hydrocarbon is naphthalene. Process according to Claim 1 or 2, characterized in that the catalyst consists of compounds of palladium and antimony. Process according to one of the preceding claims, characterized in that the water-immiscible organic solvent is a linear hydrocarbon of the formula C H, n 2n + 2 where n is the number 4-14. Process according to one of the preceding claims, characterized in that the organic solvent is a linear or cyclic aliphatic ether. 13 79294 Process according to one of Claims 1, 3 to 5, characterized in that the aromatic compound is biphenyl. Process according to one of the preceding claims, characterized in that the catalyst consists of compounds of palladium, antimony and chromium. Process according to one of Claims 1 to 6, characterized in that the catalyst consists of compounds of palladium, antimony and manganese.