FI65423C - FRUIT PROTECTION OF 2,2'-METHYLENBIS (4,6-DIALKYLFENOL) DERIVATIVES - Google Patents

Description

Preparation 2,6423 in which the bridging bond is in the para position relative to the OH group. The o, o and ο, ρ isomers are formed in the known method only to a small extent as an impurity.

Batch processes for the preparation of 2,2'-methylenebis (4,6-dialkylphenols) based on the emulsion condensation of 2,4-dialkylphenols with a condensing agent are known in the art (DE Patent 1058065 and U.S. Patent 2,796,444). For example, formaldehyde is used as a condensing agent. The condensation is carried out in the presence of an acid catalyst, e.g. sulfuric acid. The process is carried out in an aqueous emulsion of 2,4-dialkylphenol containing a surfactant and an organic solvent at a temperature of 75 to 90 ° C. The main disadvantage of this process is the formation of large amounts of wastewater contaminated with surfactant and organic solvents.

Other sources (U.S. Patents 2,758,032, 2,834,752 and 2,675,366) describe a process for preparing 2,2'-methylenebis (4,6-dialkylphenols) which comprises condensing 2,4-dialkylphenols with formaldehyde in an organic solvent at 90-110 ^ C. The method fails to ensure a high yield of pure product. The formation of wastewater is also not ruled out, as formaldehyde is used as a 37% aqueous solution.

In some processes (U.S. Patents 2,675,366 and 2,538,355), the para form is used as the condensing agent, but the desired product is obtained in low yield and poor quality. Condensation with trioxymethylene is performed in aqueous formic acid.

Therefore, the formation of wastewater is also possible.

A process for the preparation of 2,2'-methylenebis (4,6-dialkylphenols) by aqueous emulsion condensation of 2,4-dialkylphenols using a 36% aqueous solution of formaldehyde as a condensing agent is also known in the art (U.S. Patent 2,796,445).

As the 2,4-dialkylphenols, for example, 4-methyl-2-tert-butylphenol, 4-ethyl-2-tert-butylphenol and 4-ethyl-2-tert-octylphenol are used.

The reaction is carried out in the presence of an organic solvent, e.g. heptane, chlorobenzene, a surfactant and sulfuric acid as a catalyst.

The reaction temperature is maintained in the range of 30-140 ° C, e.g. between 75-90 ° C.

This results in a mixture containing the desired product. The mixture is neutralized with sodium hydroxide solution and the desired product 3,6423 is isolated by known methods such as filtration or centrifugation. The yield of the desired product is 96-98%.

The method is disadvantageous in that large amounts of wastewater containing impurities of organic solvent and surfactant are used: 12,000 to 15,000 liters of wastewater are generated per tonne of product desired.

The same drawback is characteristic of the known continuous process for the preparation of 2,2'-methylenebis- (4-methyl-6-tert-butylphenol), which process is based on the aqueous emulsion condensation of 4-methyl-2-tert-butylphenol with formaldehyde.

The object of the present invention is to eliminate the above-mentioned drawback.

The main object of the present invention is to provide a process for the preparation of 2,2'-methylenebis (4,6-dialkylphenols) which eliminates the formation of waste water and ensures a high yield of high-quality end product.

The invention relates to a process for the preparation of 2,2'-methylenebis (4,6-dialkylphenol) derivatives of the formula R1 R1 wherein R is an alkyl group having 1 to 6 carbon atoms or a cycloalkyl group, an alkyl group having 1 to 4 carbon atoms and R3 is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, by reacting 2,4-dialkylphenol of the formula

OH

ιφ R1 wherein R and R1 have the same meaning as above, to react with a condensing agent in the presence of an acid catalyst at a temperature of 30-140 ° C and separating the final product from the reaction mixture.

The invention is characterized in that the condensing agent is an aliphatic acetal of the formula (R20) 2 CHR1 (HI) »wherein R2 is an alkyl group having 1 to 3 carbon atoms and R1 is the same as in formula (I), and that the condensing agent is used in excess 65423 up to 10 moles per mole of 2,4-dialkylphenol.

Sulfur, phosphorus, perchloric, toluenesulfonic and other mineral or organic acids as well as cation exchange resins, e.g. a sulphated copolymer of styrene and divinylbenzene, can be used as catalysts.

The reaction proceeds in an acetal medium which is both a condensing agent and a solvent. Therefore, it is taken in amounts of 1 to 10 moles per one mole of 2,4-dialkylphenol (preferably 4 to 5 moles); the stoichiometric ratio is 0.5 moles of acetal per mole of 2,4-dialkylphenol. Excess acetal that does not participate in the reaction is removed and used in subsequent syntheses.

As acetals, it is preferable to use, for example, methyl, diethyl formal, dimethyl acetal, diethyl acetal, diisopropyl acetal and the like.

Condensation of 2,4-dialkylphenols with acetals allows the production of 2,2'-methylenebis (4,6-dialkylphenols) not only in the batch process but also continuously without the formation of wastewater and waste products. The yield of 2,2'-methylenebis- (4,6-dialkylphenols) obtained by this method is as high as 98%. The products are of high quality. Thus, for example, 2,21-methylenebis (4-, ethyl-6-tert-butylphenol) has a melting point of at least 128-129 ° C.

The method is technologically simple. No new hardware is needed to implement it.

Due to the use of acetals, the reaction takes place in solution.

It is not necessary to add surfactants to the reaction mixture.

The method according to the invention is carried out as follows.

The 2,4-dialkylphenol is dissolved in acetal and the solution is stirred in the presence of catalytic amounts of acid catalyst e.g. e.g. sulfuric or phosphoric acid, sulfated copolymer of styrene and divinylbenzene and the like.

The reaction can be carried out over a wide temperature range of ΙΟΙ40 ° C. This results in a reaction mixture containing the desired product. The mixture is then cooled, the catalyst is neutralized and removed. When a sulfated copolymer of styrene and divinylbenzene is used as the catalyst, it is removed from the reaction mixture immediately after cooling this mixture. Next, the unreacted acetal is distilled off from said mixture and the desired product is delivered in the form of a melt for flocculation.

5 65423 To better understand this invention, typical examples are given below.

Example 1 2 g of 4-methyl-2-tert-butylphenol, 200 ml of methylal and 2.5 g of concentrated sulfuric acid are placed in a reactor equipped with a thermometer, condenser and stirrer.

The contents of the reactor are stirred for 2 hours at 60-70 ° C. The reaction mixture obtained is then cooled to 20 [deg.] C. Calcium oxide is added to neutralize the sulfuric acid and, after stirring for a further 20 minutes, it is filtered. The unreacted methyl is distilled off from the filtrate. The residue is 2,2'-methylenebis (4-methyl-6-tert-butylphenol), m.p. 128-129 ° C. The yield of the product is 98% of theory.

Example 2 60 g of a cation exchange resin (sulfated copolymer of styrene and divinylbenzene) and a solution of 82 g of 4-methyl-2-tert-butylphenol in 180 ml of methylal are placed in the reactor described in Example 1. The contents of the reactor are stirred for 3 hours at 30-70 ° C. The resulting reaction mixture is cooled to 20 ° C, the catalyst is filtered off and the unreacted methyl is distilled off from the filtrate. The product obtained is analogous to the product of Example 1. The yield is 97% of theory.

Example 3 103 g of 2,4-di-tert-butylphenol, 220 ml of methylal and 3 g of concentrated sulfuric acid are placed in the reactor shown in Example 1. The contents of the reactor are stirred for 1.5 hours at 80-100 ° C.

Work-up of the resulting reaction mixture and isolation of the desired product are carried out as described in Example 1.

2,21-Methylenebis (4,6-ditert-butylphenol) is obtained, m.p. 141-142 ° C. The yield of the product is 98% of theory.

Example 4 A 30% methylal solution of 4-methyl-2-tert-butylphenol is passed through two series of tubular reactions filled with a cation exchange resin similar to that described in Example 2.

6 65423 The temperature in the first reactor is 50-60 ° C and in the second 70-80 ° C. The solution is introduced into the reactor at a rate of 50-60 ml / h. After the second reactor, the unreacted methyl is removed from the resulting reaction mixture. The residue is 2,2'-methylenebis (4-methyl-6-tert-butylphenol), m.p. 129-130 ° C. The yield of the product is 99% of theory. The distilled methyl is returned to prepare a solution of 4-methyl-2-tert-butylphenol.

Example 5 82 g of 4-methyl-2-tert-butylphenol, 300 ml of diethylformal and 2.5 g of concentrated sulfuric acid are charged to the reactor described in Example 1. The contents of the reactor are stirred for 2.5 hours at 85-95 ° C. Work-up of the resulting reaction mixture and separation of the desired product is carried out according to the procedure described in Example 1.

Formed 2,2'-methylenebis (4-methyl-6-tert-butylphenol), 3p. 128-129 ° C in 86% yield from theory.

Example 6 60 g of a cation exchange resin as described in Example 2 and a solution of 82 g of 4-methyl-2-tert-butylphenol in 250 ml of diethylformal are charged to the reactor described in Example 1. The contents of the reactor are stirred for 4 hours at 85-95 ° C. Work-up of the resulting reaction mixture and isolation of the desired product is carried out according to the procedure described in Example 2.

Formed 2,2'-methylenebis (4-methyl-6-tert-butylphenol), m.p. 128-129 ° C. The yield of the product is 92% of theory.

Example 7 82 g of 4-methyl-2-tert-butylphenol, 250 ml of dimethylacetal and 2.5 g of concentrated sulfuric acid are charged to the reactor described in Example 1. The contents of the reactor are stirred for 2.5 hours at 64-70 ° C. Work-up of the resulting reaction mixture and separation of the desired product is carried out according to the procedure described in Example 1.

2,2'-ethylidenebis (4-methyl-6-tert-butylphenol) is formed, m.p. 104-105 ° C. The yield of the product is 80% of theory.

Example 8 103 g of 2,4-di-tert-butylphenol, 300 ml of diethyl formal and 3 g of concentrated sulfuric acid are introduced into the reactor described in Example 1. The contents of the reactor are stirred for 25 hours at 85-95 ° C. The work-up of the obtained 7 65423 reactor mixture and the separation of the desired product are carried out according to the procedure described in Example 1.

2,2'-methylenebis (4,6-ditert-butylphenol) is obtained, m.p. 141-142 ° C, in 75% yield from theory.

Example 9 82 g of 4-methyl-2-tert-butylphenol, 400 ml of diethyl acetal and 2.5 g of concentrated sulfuric acid are charged to the reactor described in Example 1. The contents of the reactor are stirred for 3 hours at 103-110 ° C. The work-up of the obtained reaction product and the separation of the desired product are carried out according to the procedure described in Example 1.

2,2'-Ethylidenebis (4-methyl-6-tert-butylphenol) is obtained, m.p. 104-105 ° C. The yield of the product is 70% of theory.

Example 10 61 g of 2,4-xylenol, 400 ml of diisopropyl acetal and 2.5 g of concentrated sulfuric acid are charged to the reactor described in Example 1. The contents of the reactor are stirred for 3 hours at 82-90 ° C. The work-up of the obtained reaction product and the separation of the desired product are carried out according to the procedure described in Example 1.

Forms 2,21-ethylidenebis (4,6-dimethylphenol), m.p. 125-126 ° C, in 85% yield from theory.

Example 11 61 g of 2,4-xylenol, 220 ml of methylal and 2.5 g of phosphoric acid are placed in the reactor described in Example 1. The contents of the reactor are stirred for 3 hours at 95-110 ° C.

Work-up of the resulting reaction mixture and separation of the desired product is carried out according to the procedure described in Example 1.

2,2'-methylenebis (4,6-dimethylphenol) is formed, m.p. 125-126 ° C, in 83% yield from theory.

Example 12 82 g of 4-methyl-2-tert-butylphenol, 250 ml of dimethylacetal and 3 g of toluenesulfonic acid are placed in the reactor described in Example 1. The contents of the reactor are stirred for 2.5 hours at 75-80 ° C. Work-up of the reaction mixture and separation of the desired product is carried out according to the procedure described in Example 1.

2,2'-ethylidenebis (4-methyl-6-tert-butylphenol) is formed, m.p. 104-105 ° C, in 82% yield from theory.

8 65423

Example 13 82 g of 4-methyl-2-tert-butylphenol, 200 ml of methylal and 3.5 g of perchloric acid are placed in the reactor described in Example 1. The contents of the reactor are stirred for 3 hours at 30-40 ° C. The work-up of the obtained reaction mixture and the separation of the desired product are carried out according to the procedure described in Example 1.

2,2'-methylenebis (4-methyl-6-tert-butylphenol) is formed, m.p. 128-129 ° C, in 85% yield from theory.

Example 14 60 g of a cation exchange resin similar to that described in Example 2 and a solution of 87 g of 4-ethyl-2-tert-butylphenol in 200 ml of methylal are placed in the reactor described in Example 1. The contents of the reactor are stirred for 3 hours at 80-85 ° C. The work-up of the obtained reaction mixture and the separation of the desired product are carried out according to the procedure described in Example 2.

2,2'-methylenebis (4-ethyl-6-tert-butylphenol) is formed, m.p. 123-125 ° C, in 81% yield from theory.

Example 15 93 g of 4-methyl-2-cyclohexylphenol, 220 ml of methylal and 3 g of concentrated sulfuric acid are charged to the reactor described in Example 1. The contents of the reactor are stirred for 2 hours at 85-95 ° C. The work-up of the obtained reaction product and the separation of the desired product are carried out according to the procedure described in Example 1.

2.2'methylenebis (4-methyl-6-cyclohexylphenol) is formed, m.p. 118-119 ° C in 90% yield from theory.

Example 16 60 g of a cation exchange resin similar to that used in Example 2 and a solution of 82 g of 4-methyl-2-tert-butylphenol in 75 ml of methylal are placed in an airtight steel reactor equipped with a stirrer. The contents of the reactor are stirred for 1 hour at 135-140 ° C. The reactor is then opened. The work-up of the obtained reaction mixture and the separation of the desired product are carried out according to the procedure described in Example 2. 2,2'-methylenebis (4-methyl-6-tert-butylphenol) is formed, m.p. 129-130 ° C, in 99% yield from theory.

Claims (3)

9 65423 A process for the preparation of 2,2'-methylenebis (4,6-dialkylphenol) derivatives of the formula OH OH ... II R1 R1 wherein R is an alkyl group having 1 to 6 carbon atoms or a cycloalkyl group is a compound having 1 to 4 carbon atoms an alkyl group and R 1 is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, by reacting a 2,4-dialkylphenol of the formula OH Ίφ R 1 in which R and R 1 have the same meaning as above with a condensing agent in the presence of an acid catalyst at a temperature of 30- 140 ° C and separating the final product from the reaction mixture, characterized in that the condensing agent is an aliphatic acetal of formula (R20) 2 CHR1 (III) in which R2 is an alkyl group having 1 to 3 carbon atoms and R1 is as defined above, and that the condensing agents is used in excess of up to 10 moles per mole of 2,4-dialkylphenol. Process according to Claim 1, characterized in that 4 to 5 moles of acetal are used per mole of 2,4-dialkylphenol. Process according to Claims 1 to 2, characterized in that the acetal is methylal, diethylformal, dimethylacetal or diisopropylacetal.