SU1368309A1 - Method of joint production of pyrocatechol and hydroquinone - Google Patents

Abstract

The invention relates to aromatic alcohols, in particular the preparation of pyrocatechin (PCP) and hydroquinone (GC), intermediates for the production of antioxidants. The goal is to increase the PCH selectivity. The process is carried out by oxidation of phenol (I) (I) in the presence of a 0.02-0.24% aqueous solution of FeS04 (III) with the latter being fed in parallel with a molar ratio of 1: 11: 111 1: (O, 37-0 , 61) - (4,510) in an atmosphere of inert gas supplied at a rate of 0.15-1.1 min. The method ensures the reduction of up to 68% of the content of PCH in the medium of the target substances, as well as a large total concentration of them in the reaction mass, which generally increases the productivity of the process. The selectivity of the process for phenol is up to 74.3%, and for HjO up to 45%. 1 tab.

Description

The invention relates to an improved method for the joint production of pyrocatechol and hydroquinone, which are widely used as intermediates for the production of antioxidants,

The aim of the invention is to increase the selectivities for pyrocatechol by changing the mode of the process,

The goal is achieved by the method of joint production of pyrocatechol and hydroquinone by reacting phenol with hydrogen peroxide in the presence of ferric sulfate divalent as a catalyst at elevated temperature and uniformly adding an aqueous solution of hydrogen peroxide to an aqueous solution of phenol during the entire oxidation process, while ferrous sulfate is in the form of 0.020- , A 0.240% aqueous solution is added in parallel with a water solution of hydrogen peroxide and the process is carried out in an inert gas atmosphere at a volume rate of ti its filing 0,15 - 1,10. The process is conducted at 65–70 ° С with a molar ratio of phenol; hydrogen peroxide: iron sulfate, equal to 1: 0,37-0,61: 3, 0 10 -4,5 -

Carrying out the process with the stated parameters allows one to reach J more than the known solution of pyrocatechol among the target products (up to 68%), as well as a greater total concentration in the reaction mass, which determines the greater productivity of the process as compared with the known method . Besides,; heat removal is improved due to a smoother process in the first moments of the reaction. Going beyond the limits of the declared parameters leads to a deterioration in the quantitative indicators. Thus, a decrease in the phenol: hydrogen peroxide ratio eliminates the selectivity of the process and the relative content of pyrocatechin. Increasing this ratio decreases the conversion of phenol. Addition of initial reagents immediately at the beginning of the reaction, as well as an increase in the content of the catalyst in excess of the requirement: results in parameters. to cHi-selectivity and to a strong overheating of the reaction mixture (heat occurs, emission), the decrease in catalyst content increases the time 51 pro0

0

five

0

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process and leads to incomplete consumption of hydrogen peroxide.

An inert gas supply, an increase in temperature, as well as an anhydrous process are used to reduce the selectivity and decrease the productivity of the target products.

Q Phenol. In the latter case, in addition, an induction period appears and the duration of the reaction increases. A decrease in temperature leads to an increase in the duration

5 process. Finally, with an increase in the volumetric feed rate in excess of the claimed, ablation from the reaction mass of phenol begins.

Example 1 o A 400 ml batch reactor, equipped with a jacket, two dropping funnels and a magnetic stirrer, in which the temperature is maintained at 70 ° C, is placed

5 180 g (1.92 mol) of phenol, 20 g of water and 88 g (0.80 mol) of a 31% aqueous solution of hydrogen peroxide and 10 g of a 0.033% aqueous solution of FeS04 7H20 are added dropwise within 35 minutes. AT

Q the reaction during the reaction mass is a stream of argon with a bulk velocity O ,, 50 minutes After completion of the addition of the reagents, the reaction mass is kept for 5 minutes and analyzed by GLC for the content of phenocol pyrocatechol and hydroquinone, as well as iodometrically for the content. The content of pyrocatechin 24.95 g, hydroquinone 13.27 g, phenol 135.8 g, 0.0 g. The final volume of the reaction mass is 290 ml, the total concentration of the target products in it is 1.198 mol / l. Under a residual pressure of 135 mm Hg, water was removed from the reaction mass using a distillation column. Then, at a pressure of 90 mm rToSt. 134.9 g of phenol were added. Then, on a vacuum evaporator with a residual pressure of 8 mm Hg. a mixture of pyrocatechol and hydroquinone is separated. Finally, this mixture is distilled at a residual pressure of 11 mm Hg, and 24.89 g of pyrocatechin and 13.19 g of hydroquinone are obtained. The ratio of pyrocatechol to hydroquinone is 1.88; 1 (6552% pyrocatechol among the target products). The selectivity for phenol is 73578% and is selectivity for hydrogen peroxide 43e4%.

Example 2. The conditions of example 1, with the difference that 132 g (1.2 mol) of a 31% aqueous solution of hydrogen peroxide were added. The content of pyrocatechin 33.53 g, hydroquinone 17.23 g

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phenol 113.3 g, 0.2 g. Ratio of pyrocatechin to hydroquinone 1.95: 1 (67% pyrocatechin among the target products). The final volume of the reaction mass was 334 ml, the total concentration of the target products in it was 1.38 mol / l. Selectivity for phenol 65%, selectivity for hydrogen peroxide 38.5%.

The results of examples 1-19 are summarized in table.

As follows from the table, carrying out the process with the stated parameters allows increasing the content of pyrocatechin among the target products (up to 68%), as well as increasing their total concentration in the reaction mass, which determines the productivity of the process. In addition, heat removal during the reaction is improved and separation of the reaction mixture is simplified (Examples 1-3, 6, 7, 10, 12 and 14). A decrease in the ratio of phenol and hydrogen peroxide (Example 4) reduces the selectivity of the process, as well as the percentage of pyrocatechol among the target products. An increase in this ratio (Example 5) leads to a low degree of phenol conversion, which decreases the productivity of the target products. A decrease in the catalyst content (Example 8) increases the process time and leads to incomplete consumption of hydrogen peroxide. An increase in its content of more than claimed parameters (Example 9) leads to a decrease in the selectivity of the process and to a strong overheating of the reaction mixture so that the process becomes: uncontrollable. The same results are obtained by adding the initial reagents immediately at the beginning of the reaction without dosing (examples 17 and 18).

measures 15) leads to an increase in its duration, and hydrogen peroxide is not consumed completely. Increasing the temperature reduces the selectivity and productivity of the target products (Example 16). Carrying out the process using anhydrous phenol increases the reaction time due to the occurrence of the induction period and reduces the selectivity of the process (Example 19).

PRI me R 20. Continuous production of pyrocatechin and hydroquinone.

Continuous hydroxylation of phenol with hydrogen peroxide is carried out in a cascade of 8 complete mixing reactors. Each 50 ml reactor is equipped with a jacket, which is supplied with coolant, a turbine agitator, three baffles, two drip funnels and a barbater, through which inert gas is fed. A solution of water in phenol with a phenol concentration of 9.5 mol / l is pumped into the first reactor at a speed of 5.30 ml per minute. A 31% HjOz solution at a rate of 0.26 ml / min and a 0.2% solution of the catalyst FeS04 7H O are fed into each reactor at a rate of

thirty

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0.125 ml / min, and also pass argon current with a volumetric rate of 0.25 min.

Thus, per minute, 4.733 g of phenol, 0.712 g, which is 0.05035 mol / min and 0.0210 mol / min, are supplied to the cascade, respectively. 3.377 g / min of phenol, 0.397 g / min of hydroquinone, and 0.794 g / min of pyrocatechin are released from the last reactor. The volume of the reaction mixture in each reactor is chosen so that the arrival time is everywhere 5 minutes. The total contact time is 40 minutes.

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Selectivity for phenol 73 mol.% When the degree of conversion of phenol 29.5%. The selectivity of 51.6%. The content of pyrocatechin among the target pro-. The supply of inert ga-QQ products 67.0% is insufficient. The total volumetric flow leads to a drop in the selectivity of the reaction mixture leaving the preparatory process and a decrease in the productivity of the target products (Example 13). With an increase in the volumetric flow rate of the inert gas in excess of the claimed content, the ablation of the phenol from the reaction mass begins: in Example 11 it is

the last reactor is 7.50 ml / min. Con (1 (concentration of the desired products in the reaction mixture was 1.371 mol / l.

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Thus, from the data of the table and Example 20, it follows that the observance of the stated conditions of the process, provides an increase in production of 12.5% of the consumed phenol. Reducing the process temperature (at

five

0

measures 15) leads to an increase in its duration, and hydrogen peroxide is not consumed completely. Increasing the temperature reduces the selectivity and productivity of the target products (Example 16). Carrying out the process using anhydrous phenol increases the reaction time due to the occurrence of the induction period and reduces the selectivity of the process (Example 19).

PRI me R 20. Continuous production of pyrocatechin and hydroquinone.

Continuous hydroxylation of phenol with hydrogen peroxide is carried out in a cascade of 8 complete mixing reactors. Each 50 ml reactor is equipped with a jacket, which is supplied with coolant, a turbine agitator, three baffles, two drip funnels and a barbater, through which inert gas is fed. A solution of water in phenol with a phenol concentration of 9.5 mol / l is pumped into the first reactor at a speed of 5.30 ml per minute. A 31% HjOz solution at a rate of 0.26 ml / min and a 0.2% solution of the catalyst FeS04 7H O are fed into each reactor at a rate of

0

0.125 ml / min, and also pass argon current with a volumetric rate of 0.25 min.

Thus, per minute, 4.733 g of phenol, 0.712 g, which is 0.05035 mol / min and 0.0210 mol / min, are supplied to the cascade, respectively. From the latter reactor, 3.377 g / min of phenol, 0.397 g / min of hydroquinone and 0.794 g / min of pyrocatechin are released. The volume of the reaction mixture in each reactor is chosen so that the arrival time is everywhere 5 minutes. The total contact time is 40 minutes.

Selectivity for phenol 73 mol.% When the degree of conversion of phenol 29.5%. The selectivity of 51.6%. The concentration of pyrocatechin among target products is 67.0%. The total volumetric flow of the reaction mixture leaving the

Selectivity for phenol 73 mol.% When the degree of conversion of phenol 29.5%. The selectivity of 51.6%. The content of pyrocatechin among the target products is 67.0%. The total volumetric flow of the reaction mixture leaving the

the last reactor is 7.50 ml / min. Con (1 (concentration of the desired products in the reaction mixture was 1.371 mol / l.

Selectivity for phenol 73 mol.% When the degree of conversion of phenol 29.5%. The selectivity of 51.6%. The content of pyrocatechin among target products of QQ is 67.0%. The total volumetric flow of the reaction mixture leaving the

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Thus, from the data of the table and Example 20, it follows that the observance of the stated conditions for the conduct of the process ensures an increase in the production of 1368309®

Claims (1)

pyrocatechin, as well as the formula of the invention simplifies the technology due to the provisional method of jointly producing pyrocals of a smooth temperature regime, catechin and hydroquinone by mutually simplifying the separation of the reactive action of phenol with algae peroxide, because as a result of the reaction in the presence of 0.02-0.24% aqueous solution more concentrated solutions of the target products. ferrous sulfate bivalent solution at 65-70 С and uniform yes in the presence of 0.02-0.24% water ferrous sulfate bivalent solution at 65-70 С and uniform  8 "80 32 0.066 8.0 8B, 0 nineteen 180 0.066 8.0 88.0 1: 0.42: 12.4-10 thirty 4.7 0.004 -, 0.3: 0.33: 4.5l-tO (E5g-ny solution of I.O.) 1: 0.42M2.4-) 0- 70 40 0.50 30.8 70 65 0.50 28.1 60 40 t8,4 addition of: an aqueous solution of hydrogen peroxide at a molar ratio of phenol: hydrogen peroxide: catalyst, equal to 1: 0.37-0.61: 3.0.10-4, characterized in that, in order to increase the selectivity of pro98.0 0.9, 14.67 58.1 41.6 100 27.4 2.8.t 66.9 45.2 100 3.25 2.57 90.0 50.0 the process of pyrocatechin, in parallel with the addition of hydrogen peroxide to the solution, evenly add the catalyst solution, and the process is carried out in an atmosphere of inert gas at a flow rate of 0, 15-1.1 minutes 7 1,147 61.0 The catalyst was added all at once at the beginning of the reaction. Severe overheating. The mixture is partially ejected from the reactor. Process not controlled Peroxyl hydrogen is added immediately at the beginning of the reaction. Severe overheating, unmanaged process 261 1,400 68.0 45 1,174 55i84 The catalyst was added without dosing at the beginning of the reaction.