NL8320436A - PROCESS FOR THE PREPARATION OF BETA - (4-HYDROXY 3,5-DI-TERT.BUTYLPHENYL) PROPIONIC ACID ALKYL ESTERS. - Google Patents

Description

\ -1- 24803 / Vk / mvl 8 3 2 0 4; :: 3

Short designation: Process for the preparation of $ - (4-hydroxy 3,5-di-tert-butylphenyl) -propionic acid alkyl esters.

The present patent application relates to the organic synthesis and more particularly to a process for the preparation of B- (4-hydroxy 3,5-di-tert-butylphenyl) -propionic acid alkyl esters.

Japanese patent 62731, 1973 discloses a process for the preparation of alkyl esters of B- (4-hydroxy 3,5-di-tert-butylphenyl-propionic acid) by reacting an alkyl acrylate with 2.6-10 di- tert-butylphenol at a temperature between 110 and 120 ° C in the presence of a catalyst, metallophenoxide, such as sodium phenolate, aluminum phenolate or potassium 2,4-dimethylphenolate in an amount of 50 mol%, based on 2,6-di-tert-butylphenol When methyl acrylate is used, the yield of B- (4-hydroxy 3,5-di-tert-butylphenyl) -15 propionic acid methyl ester after 5 hours of reaction is 82.3%, however, in this process a large amount of insufficiently active catalyst becomes which adversely affects yield and separates the desired product.

A process is also known for the preparation of alkyl esters of 8- (4-hydroxy 3,5-di-tert-butylphenyl) -propionic acid by reacting an alkyl acrylate with 2,6-di-tert-butylphenol in the presence of 5-25 mol% of an alkali metal base, such as an alkali metal hydroxide, at a temperature between 25 and 200 ° C. Thus, after heating 37.3 parts by weight of 2,6-di-tert-butylphenol and 17.7 parts by weight of methyl acrylate and 3.5 parts by weight of potassium hydroxide in 500 parts by weight of t-butyl alcohol for 18 hours, at a temperature of 50 ° C, after which neutralization takes place, extraction with diethyl ether and fractionation under reduced pressure, the desired product is obtained in the form of a yellow oil which crystallizes after storage into crystals with a melting point of 63-64.5 ° C ( see U.S. Patent 3,247,240). This patent also states that the yield of the desired product is less than the yield of this product obtained under comparable conditions but using 2.1 parts by weight of metallic potassium in t-butanol. Therefore, in the process using potash-35 hydroxide as a catalyst, the desired yield of product becomes lower than in the process using potassium as a catalyst based on an alkali metal. Furthermore, organic 8320438-2-24803 / Vk / mvl solvents are used in the process, which makes separation of the desired product more difficult. The process also gives low productivity, which is also indicative of insufficient activity of the catalyst, potassium hydroxide or metallic potassium in tert-butanol. Furthermore, the use of metallic potassium can lead to an explosion.

The present invention is directed to obtaining a process for preparing 8- (4-hydroxy 3,5-di-tert-butylphenyl) -propionic acid alkyl esters with an active catalyst and under conditions such that it allows the desired increase yield of product, reduce the time for the process and avoid the use of organic solvents.

This object is achieved by using a process for preparing 8- (4-hydroxy 3,5-di-tert-butylphenyl) -propionic acid alkyl esters by reacting 2,6-di-tert-butylphenol with a alkyl acrylate in the presence of a catalyst containing an alkali metal hydroxide at a temperature between 70 and 150 ° C, using, according to the present invention, 2,6-di-tert-butylphenol and alkyl acrylate in a molar ratio of 1: 1-1, respectively , 3 and the process is carried out in the presence of a catalyst containing, in addition to the alkali metal hydroxide, a 4-R-2,6-di-tert-butylphenolate of an alkali metal and 4-R-2,6-di-tert-butylphenol wherein R is H, CH 2, C 1 CH 2) ^ in the following amounts of the above compounds, expressed in parts by weight: alkali metal hydroxide 0.05-20 25 alkali metal 4-R-2,6-di-tert-butyl - _ Q, phenolate 2,05-yy, y4 4-R-2,6-di-tert-butylphenol rest

The catalyst is used in an amount ranging from 2 to 20 mol%, based on 2,6-di-tert-butylphenol based on the total amount of alkali metal hydroxide and 4-R-di-tert-butyl phenolate of the alkali metal.

The catalyst used in the process according to the invention shows a high activity which, in combination with the process conditions, allows a reduced duration of the process and a reduction to 1-2 hours. It also becomes possible to avoid the use of organic solvents, which results in higher process productivity and reduced energy consumption. The yield of the desired product is between 86 and 98% · 83 2.0 4 36 -3- 24803 / Vk / mvl

As mentioned previously, the process is based on the reaction between 2,6-di-tert-butylphenol and the alkyl acrylate, conducted at a temperature between 70 and 150 ° C. Below 70 ° C, it is not recommended to carry out the reaction according to the invention because of the reduced speed of the reaction at a temperature below 70 ° C. It is also not recommended to carry out the process at a temperature above 150 ° C, due to the formation of by-products.

The reaction between 2,6-di-tert-butylphenol and the alkyl acrylate should preferably be carried out at a molar ratio of 10 and 1: 1-1.3, respectively. With an excess of 2,6-di-tert-butylphenol, it is undesirable to carry out the reaction because a mixture of 2,6-di-tert-butylphenol and an alkyl ester of 8- (4-hydroxy 3,5-di -t-butylphenyl) -propionic acid is formed, the separation of which in the individual components is rather complicated. The use of alkyl acrylate in an excess of more than 1.3 times does not result in an increased conversion of 2,6-di-tert-butylphenol.

The reaction process between 2,6-di-tert-butylphenol and alkyl acrylate should preferably be carried out in the presence of a catalyst in an amount of 2 to 20 mol% based on 2,6-di tert-butylphenol, based on the total amount of alkali metal hydroxide and alkali metal 4-R-2,6-di-tert-butylphenolate. The amount determined is based on the catalyst composition, the temperature during the reaction and the amounts of reagent. It is not recommended to use the catalyst in an amount of less than 2 mol%, because there is a possibility that the activity may be reduced.

Also, an amount of catalyst above 20 mol% is ineffective because of the limited solubility of the catalyst in the mixture of 2,6-di-tert-butylphenol with the alkyl acrylate.

The catalyst used in the process of the invention is prepared in a manner known per se, for example, according to U.S. Pat. No. 2,745,882, by 4-R-2,6-di-tert-butylphenol, wherein R is the meaning of H, CH 2, C 1 CH 2) -, to be heated with an alkali metal hydroxide in an inert gas at a temperature between 50 and 150 ° C in an organic solvent such as xylene, heptane, azeotropically distilling off water and distilling off the solvent from the reaction mixture. The amounts of the components in the catalyst can be varied by changing the amount of starting materials and the reaction time, which is controlled by measuring the amount of distilled water in the azeotropic distillation.

The calculated amounts of 2,6-di-tert-butylphenol and alkyl acrylate are added to the catalyst prepared as indicated above. The reaction can be performed in both an open and a closed system (autoclave). When the reaction is carried out between 2,6-di-tert-butylphenol and alkyl acrylate in an open system (under atmospheric pressure), a reflux condenser is used. The reaction takes place at a temperature between 70 and 150 ° C, but it is desirable that the process be carried out at the boiling point of the reaction mixture. After the completion of the reaction, the desired product is recovered by fractionation under reduced pressure or by crystallization. The method according to the present invention is easy to perform both with regard to the technology to be used and the equipment to be used therewith.

The invention is further illustrated by the following examples. The composition of the catalyst and its consumption in the examples are shown in the table after the examples.

Example I

In a flask equipped with a reflux condenser, a water collecting vessel and an inert gas supply tube, 42 g (0.2 mol) of 2,6-di-tert-butylphenol was heated under nitrogen with 7 g (0.125 mol) of potassium hydroxide in 250 ml of xylene and at a reflux temperature of 88-140 ° C. Thereby, 2 ml of water was collected in the receiving vessel for 1.5 hours. The solvent was distilled off in an amount of 200 ml, the residue filtered off and heated at a temperature of 150 ° C for 10 minutes. The catalyst thus obtained had the following composition, expressed in parts by weight; 0.5 parts of potassium hydroxide, 99 parts of 2,6-di-tert-butylphenolate, 0.5 parts of 2,6-di-tert-butylphenol as listed in the table.

To 0.43 g of catalyst of the above composition was added 9 95 g (0.048 mol) of 2,6-di-tert-butylphenol and 5 ml (0.056 mol) of methyl acrylate. The reaction mixture was refluxed for 2 hours, raising the temperature from 70 to 150 ° C, then the reaction mixture was cooled to 70 ° C, neutralized with 5% sulfuric acid. The methyl ester of 8- (4-hydroxy 3,5-di-tert-butylphenyl) -8320436-524803 / Vk / mvl propionic acid was filtered off in an amount of 14.5 g (98% of the theoretical amount) and a melting point of 64-65 ° C.

Example II

In the same manner as described in Example 1, from 45 g (0.2 mol) 4-methyl 2,6-di-tert-butylphenol, 5 g (0.125 mol) sodium hydroxide in 250 ml xylene, a catalyst was obtained, of which the composition is indicated in the table.

To 0.93 g of catalyst was added 20.4 g (0.099 mol) of 2,6-di-tert-butylphenol together with 9.5 ml (0.105 mol) of methyl acrylate and the procedure was further carried out as described in Example 1. After the completion of the reaction, 26 g (90% of the theoretical amount) of 8- (4-hydroxy-3,5-di-tert-butylphenyl) -propionic acid methyl ester were separated by fractionation under reduced pressure and this substance had a melting point of 64-65 ° C.

Example III

The catalyst was prepared in the same manner as in Example 1 except that the filtered residue (1/14 part of the total amount) was mixed with 103 g (0.5 mol) of 2,6-di-tert. butylphenol and held at a temperature of 150 ° C for 15 minutes under reduced pressure. The mixture was then cooled and mixed with 50 ml (0.56 mol) of methyl acrylate, and the reaction mixture was refluxed for 3.5 hours. The reaction mixture was then cooled, neutralized and 490 g (96% of theory) of methyl ester of 8- (4-hydroxy 3,5-di-tert-butylphenyl) -propion-25 acid was separated, m.p. 64-65 ° C.

Example IV

In a device similar to that described in Example I, 20.6 g (0.1 mole) of 2,6-di-tert-butylphenol was heated with 5.6 g (0.1 mole) of potassium hydroxide and 250 ml of heptane at a temperature of 79 ° C and 1.4 ml of water was collected in the collection vessel. The solvent was distilled off under reduced pressure to obtain the catalyst whose composition is shown in the table.

To 1.05 g of catalyst was added 9.6 g (0.048 mol) of 2,6-di-tert-butylphenol and 5.8 ml (0.064 mol) of methyl acrylate. The reaction mixture was autoclaved at a temperature of 140 ° C for 3.5 hours and after the treatment similar to that in Example I, 12.5 g (86% of the theoretical amount) of methyl ester of (3- (4-hy- droxy 3,5-di-tert-butylphenyl) -propionic acid obtained with a melting point of 64-65 ° C.

8320436 ♦ -6- 24803 / Vk / mvl

Example V

A catalyst of a composition as stated in the table was prepared under the conditions as in Example I with the only difference that 26.2 g (0.1 mol) of 2,4,6-tri-tert-butylphenol 5 was heated with 2.76 g (0.069 mol) of sodium hydroxide in 250 ml of xylene and after completion of the reaction, the solvent was distilled off under reduced pressure.

To 5.0 g of catalyst was added 20.6 g (0.1 mole) of 2,6-di-tert-butylphenol and 9 ml (0.1 mole) of methyl acrylate. The reaction mixture was heated at a temperature of 140 ° C for 2.5 hours and 25.4 g (88% of the theoretical amount) of methyl ester of 3- (4-hydroxy 3,5-di-tert-butylphenyl) propionic acid was separated under fractionation under reduced pressure, mp 64-65 ° C.

Example VI

A catalyst was prepared in the same manner as in Example 1 except that the residue after filtration was heated to a temperature of 150 ° C under reduced pressure (20 mm Hg) and 2,6-di-tert-butylphenol was added. distilled. Then, in a three-necked flask, 39.14 (0.16 mole) of 2,6-di-tert-butylphenol, 2.44 g (0.01 mole) of catalyst (listed in the table) and 2.35 ml (0, 25 mol) of methyl acrylate. The mixture was heated and kept at a temperature of 120 ° C for 1 hour and also at 130 ° C for 1 hour. The reaction mixture was then cooled to a temperature of 80 ° C and diluted with 50 ml of gas oil. The solution in the gas oil was mixed with 48 ml of 3% hydrochloric acid, washed with water until neutral, the organic layer was separated and evaporated, the residue was distilled under reduced pressure of 20 mm Hg and the intended fraction had a boiling range of 200 to 204 ° C to obtain 52.9 g (0.5% of theory) of the methyl ester of 8- (4-hydroxy 3,5-di-tert-butylphenyl) propionic acid, m.p. 64-65 ° C.

Example VII

A catalyst was prepared in the same manner as in Example 1 except that 42 g (0.02 mole) of 2,6-di-tert-butylphenol was heated with 5 g (0.125 mole) of sodium hydroxide in 250 ml. xylene, followed by heating the residue at a temperature of 150 ° C under a reduced pressure of 20 mm Hg. Thereafter, from a mixture of 39.14 g (0.19 mol) of 2,6-di-tert-butylphenol and 51 ml (0.24 mol) of butyl-8320436 ► -7- '24803 / Vk / mvl of acrylate in the presence of 2.28 g (0.01 mol) of catalyst under the conditions of Example VI, followed by neutralization with acetic acid, washing with water and distillation under reduced pressure, 59 g (88% of the theoretical amount) of butyl ester of β- (4-hydroxy-5 3,5-di-tert-butylphenyl) propionic acid obtained with a boiling range of 205-209 ° C.

Example VIII

To a 50 L reactor connected to a heat exchanger, 20.6 kg (100 moles) of the commercially available 2,6-di-tert-butyl-10 phenol (main product content is 98.5 wt. %) and 0.35 kg (6.3 mol) of potassium hydroxide and the catalyst was prepared under the conditions of Example 1 at a temperature between 110 and 130 ° C. Then 11.1 kg (130 mol) of the commercially available methyl acrylate with a water content of 0.1% by weight was added. The reaction was carried out at a temperature of 135-140 ° C for

1.5-2 hours. The methyl ester of B- (4-hydroxy 3,5-di-tert-butylphenyl) propionic acid was recovered by distillation under reduced pressure in an amount of 27.3 kg (95% of the theoretical amount) to give a product with a boiling point of 202-204 ° C under 20 mm Hg. Example IX

A catalyst was prepared in the same manner as in Example I from 20.6 g (0.1 mole) of 2,6-di-tert-butylphenol and 5.6 g (0.1 mole) of potassium hydroxide in 250 ml of xylene with this difference, that about 1.8 ml of water was collected at the boiling point of the mixture. 20.6 g (0.1 mole) of 2,6-di-tert-butylphenol and 10.5 g (0.05 mole) of acrylic acid bis-diethylene glycol ester were added to 1.5 g of the catalyst. The mixture was maintained at a temperature of 135 ° C for 2.5 hours, after which the reaction mixture was cooled to a temperature of 65 ° C and diluted with 300 ml of gas oil, neutralized with 3% hydrochloric acid, washed with water until neutral reaction. The solvent was distilled off from the organic layer under reduced pressure before crystallization started. The yield of bis-diethylene glycol ester of β-{4-hydroxy 3,5-di-tert-butylphenyl) propionic acid was 26 g (86% of the theoretical amount). The melting point was 85-87 ° C.

Comparative example 1

To a mixture of 9.95 g (0.048 mol) of 2,6-di-tert-butylphenol and 0.2 g (0.0036 mol) of potassium hydroxide as catalyst, 5 ml (0.056 mol) of methyl acrylate was added and after carrying out the reaction under conditions 8320430 ft -8- 24803 / Vk / ml mentioned in Example I, followed by fractionation under reduced pressure, 1.77 g (12% of the theoretical amount) of methyl ester of 6- (4-hydroxy 3, 5-di-tert-butylphenyl) propionic acid is obtained. The product had a melting point of 64-65 ° C.

The process for the preparation of 8- (4-hydroxy 3,5-di-tert-butylphenyD-propionic acid alkyl esters of the present invention makes it possible to obtain the desired product in a yield of 86 to 98%, the purity of which is increased by a more complete continuation of the reaction, reducing the consumption of catalyst 10 by a factor of 2.5, shortening the reaction time by a factor of 1.5-4, allowing the process to be intensified and minimizing the unwanted polymerization of alkyl acrylate and simplifying the process by avoiding the use of a solvent and preventing the formation of waste water, and the process being carried out more safely thanks to the use of a harmless catalyst.

TABLE

catalyst composition for 4-R-2,6-di-tert-6-di-amount * 1 alkali metal butylphenolate. ". Ί meaning catalyst base, 66 hydroxide of the alkali metal of R based on 2.6-20. . phenol .... , Metaal 'metal di-tert-butyl- (parts by weight) __ (parts by weight) (parts by weight) ___ phenol (mol%) I 0.5 99 0.5 H 4 II 1.8 95.5 2 .7 CH3 4.1 25 III 0.05 2.05 97.90 H 2 IV 20 77 3 H 10 V 1 68 31 c (CH3) 3 20 VI 0.05 99.94 0.01 H 5.2 30 VII 0.05 99.94 0.01 H 6.25 VIII 1.6 6.7 91.7 H 6.3 IX 10 88 2 H 7.5

Note *) calculated for the total amount of alkali metal hydroxide and the alkali metal of 4-R-2,6-di-tert-butylphenolate.

8320436 Λ -9- 24803 / Vk / mvl

Industrial applicability.

The process according to the invention makes it possible to prepare alkyl esters of 3- (4-hydroxy 3,5-di-tert-butylphenyl) -propionic acid which are suitable as anti-oxidants for polymeric substances and the preparation of thermostabilizers for polyolefins, polyamines and other polymers.

In summary, the invention therefore relates to a process for the preparation of β- (4-hydroxy 3,5-di-tert-butylphenyl) -propionic acid alkyl esters by reacting 2,6-di-tert-butylphenol with 10 an alkyl acrylate at a molar ratio of 1: 1-1.3 and at a temperature between 70 and 150 ° C in the presence of a catalyst consisting of an alkali metal hydroxide, an alkali metal 4-R-2,6-di-tert. butylphenolate and 4-R-2,6-di-tert-butylphenol, wherein R has the meaning of H, CH 2, C 1 CH 2) in the following amounts by weight: 15 alkali metal hydroxide 0.05-20 alkali metal 4-R-2, 6-di-tert-butylphenolate 2.05-99> 94 4-R-2,6-di-tert-butylphenol moiety, using the catalyst in an amount of 2 to 20 mol% of 2,6-di- tert-butylphenol, based on the total amount of alkali metal hydroxide and alkali metal 4-R-2,6-di-tert-butyl phenolate.

8320436

Claims (2)

4-R-2,6-di-tert-butylphenol residue, which catalyst is used in an amount of 2 to 20 mol% of 2,6-di-tert-butylphenol, based on the total amount of alkali metal hydroxide and alkali metal 4- R-2,6-di-tert-butylphenolate. 8320436 ♦ v -11- 24803 / Vk / mvl IMPROVED CONCLUSION for international patent application PCT / SU / 83/00045. Process for the preparation of 8- (4-hydroxy 3,5-di-tert-butyl-phenyl) -propionic acid alkyl esters by reacting 2,6-di-tert-butylphenol with an alkyl acrylate in the presence of a catalyst which an alkali metal hydroxide at a temperature between 70 and 150 ° C, characterized in that 2,6-di-tert-butylphenol and the alkyl acrylate are used in a molar ratio between 1: 1-1.3 and the process is continued in presence of a catalyst containing, in addition to the alkali metal 10-hydroxide, the alkali metal of 4-R-2,6-di-tert-butylphenolate and 4-R-2,6-di-tert-butylphenol, where R is H, CH 2 <RTI ID = 0.0> CiCH </RTI> in the following amounts of the above compounds, expressed in parts by weight: alkali metal hydroxide 0.05-20 15 alkali metal of 4-R-2,6-di-tert-butylphenolate 2.05-99 »94 4-R-2,6-di-tert-butylphenol residue, the catalyst being used in an amount of 2 to 20 mol% of 2,6-di-tert-butylphenol, based on the total amount of the alkali metal hydroxide and alkali metal 4-R-2,6-di-tert-butyl-20 phenolate. Eindhoven, July 1985 «8320436