SU263492A1 - METHOD FOR OBTAINING COMPLEX PENYL AIR - Google Patents

Description

This invention relates to a process for the preparation of phenyl ester of saturated aliphatic or cycloaliphatic carboxylic acids, which are valuable raw materials for various branches of the chemical industry.

It is known that acetic acid phenyl ester, together with diphenyl, is obtained from benzene and acetic acid in the liquid phase in the presence of palladium acetate in a stoichiometric reaction. The disadvantage of the method is that the selectivity of this reaction with respect to phenylacetate is small, the method is carried out in a discontinuous manner.

According to the proposed method, a mixture of benzene, saturated aliphatic carboxylic acids and molecular oxygen in a gas or vapor phase is reacted in the presence of a compound of an eighth group element of a periodic system, the valency of which in the compounds does not exceed 4 or a mixture of these compounds.

As carboxylic acids, saturated aliphatic or cycloaliphatic monocarboxylic acids with up to 8 carbon atoms or their mixture are used. Suitable, for example, propionic, oily and iso-butyric acids, especially acetic acid. It is advisable to use acids in a concentrated form, for example, acetic acid - in the form of glacial acid. A small amount of water in the acids used is acceptable. You can use a mixture of carboxylic acids with their anhydrides.

Oxygen is supplied as such or in the form of air. When the components of the reaction are circulated, it is best to use pure or almost pure oxygen.

The starting materials may contain substances that do not interfere with the preparation of the main reaction product, for example, saturated hydrocarbons, noble gases, carbon oxides or water.

Elements such as radium, iridium, platinum, ruthenium and especially palladium compounds can be used as compounds of noble metals. The noble metal compounds can also be used as a mixture with one another or in a mixture with other metals. They can be, for example, during the reaction, partially converted to the corresponding noble metals.

Noble metal compounds such as their salts with saturated aliphatic or cycloaliphatic carboxylic acids and their hydroxides are used. Salts of noble metals and those carboxylic acids, which are used in the reaction as a component, are the greatest advantage.

In addition, complexes of salts of noble metals with unsaturated organic compounds, in particular complexes of salts of noble metals with aromatic compounds, for example, with benzene, can be used.

Noble metal compounds can be used on their own or on a carrier, for example, on alumina, aluminum silicate, silica gel, charcoalites, pumice, clay. The application of the noble metal compounds to the carrier is made by the known method.

The concentration of the noble metal compound on the support can vary widely. In many cases, even low concentrations of these compounds are effective, for example, 0.1: 10 wt.% Based on the total weight of the system consisting of the support and the catalyst. However, phenyl ether, and in this case phenol, is obtained already at a concentration of noble metal compounds below 0.1 wt.%, For example, up to 0.05 wt.%, Or at lower concentrations. The compounds can be used in a concentration above 10% by weight.

Along with compounds of noble metals, the catalyst may contain small amounts, for example, up to 50 mol. % of other metals or metal compounds that are not themselves active, for example, gold, copper, silver, iron, manganese, and their compounds such as gold oxide, copper acetate, silver propionate, ferrous sulfate, manganese phosphate and t dd

Particularly good results are achieved with the use of activators, which can be applied to salts of strong bases and weak acids, for example, carbonates or acetates of alkali or alkaline earth metals, or zinc or cadmium. Salts which, with the carboxylic acids used, form a buffer system, in particular sodium or borax phosphates, can also be used as activators. Activators in the form of alkaline salts of carboxylic acids used have a particularly great effect. In the case of the conversion of acetic acid, for example, alkali metal acetate is often used, as well as in a mixture with the other above-mentioned acetates. The activator in solid form can be applied on the same carrier as the catalyst, can be, for example, dissolved in the carboxylic acid used, or suspended in it, or reacted with this acid.

The amount of activator on the catalyst can vary within wide limits, preferably from 0.1 to 10% by weight.

Temperature varied over a wide range. It is advisable to carry out the reaction at temperatures from 75 to 300 ° C, preferably from 100 to 250 ° C.

Maximum pressure, with nonylenoM and increased, the best results are achieved at pressures ranging from 1 to 25, in particular from 1 to 10 atm.

The proposed method makes it possible to obtain expensive aromatic products, namely phenyl ether and phenol, from technical starting products using the catalytic oxidation method at relatively low concentrations.

temperaturah. The method is highly selective and economical.

Example 1. 400 ml of sintered silicic acid are impregnated with 6.35 g of palladium acetate and 4.25 g of potassium acetate dissolved in 130 ml

acetic acid. The contact catalyst made in this way is dried in vacuum at 50 ° C and introduced into a reaction tube heated with an inner diameter of 30 mm. Through a catalyst comprising

1.5 wt.% Palladium and 1.7 wt.% Potassium, at a temperature of 170 ° C and a pressure of 5 atm, 3.2 mol of benzene, 0.64 mol of oxygen and 3.2 mol of acetic acid containing 0 before evaporation are passed through, 8 wt.% Potassium acetate. Gazov

the mixture leaving the reactor is cooled, the condensate formed is processed. In 1 hour, 1.4 g of phenyl ester of acetic acid and 0.09 g of phenol are obtained. The output in terms of the entered benzene is close to 100%.

The unreacted starting materials after separation of the final products (carbon dioxide and water are only partially removed) are returned to the process. The resulting mixture of phenyl ester of acetic acid and phenol is evaporated, diluted with water vapor (molecular ratio of water and ether 1: 1) and passed through a quartz tube at 600 ° C for 12 seconds. At the same time, 72% of the ester is washed in phenol.

The reaction products are separated by distillation, the unreacted ether is reintroduced into the hydrolysis zone, and the resulting acetic acid, after separation of most of the water, is fed to the contact.

Example 2. Pre-converted into a mixture containing 0.1 mol of benzene and acetic acid, together with 1 l of oxygen and 0.5 l of nitrogen per 1 hour, passed through 75 ml of catalyst at 170 ° C and normal

the pressure in the heated glass reactor with an internal diameter of 20 mm and a length of 300 mm.

The catalyst contains it (on a carrier of silicic acid, the diameter of the granules 0,25-

0.5 L1m) 3 wt.% Palladium in the form of hydroxide. To prepare the catalyst, the carrier impregnated with palladium chloride is mixed with dilute sodium alkali, washed thoroughly and dried at 130 ° C for 1 hour. After that, 1% by weight of potassium and 2% by weight of cadmium in the form of their acetate are applied to the hydrate oxide catalyst. 5 selectivity in terms of converted bepzol. Unreacted spova starting material is introduced into the reaction cycle. The subject matter of the invention 1. A method of producing a phenyl ester using benzene, characterized in that, in order to increase the selectivity of the process, benzene is reacted with ali-fatic or carboxylic aliphatic carboxylic acid and molecular oxygen at a temperature of 75-300 ° C at a pressure of from atmospheric to 25 atm in the presence of a catalyst — compounds of elements of group VIII of the periodic system, the valence of element in which does not exceed 4, or a mixture of ethn compounds. 6 2. A method according to claim I, characterized in that the process is carried out at a temperature of 100-250 ° C and a pressure of 1-10 atm. 3. The method according to paragraphs. 1 and 2, characterized by the i & u, that palladium hydroperoxide, a palladium salt, and a saturated aliphatic and / or cycloaliphatic carbopic acid are used as compounds of the elements of group VIII. 4. The method according to paragraphs. 1, 2 and 3, characterized in that a catalyst is used on a carrier, for example, clay, silica gel, silicate, zeolite. 5. A method according to claim 1, characterized in that an activator, for example an alkali salt of a carboxylic acid, is introduced into the catalyst.