JPS6212786B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention is based on the general formula () (In the formula, R ₁ and R ₂ each independently represent a C _1-8 alkyl group, R ₃ and R ₄ each independently represent a hydrogen atom or an alkyl group, and R ₅ represents a C _{1-20 alkyl} group. This invention relates to an improved method for producing phenols represented by (representing an alkyl group). Phenols represented by the general formula () are useful as stabilizers for many organic compounds such as plastics such as polyethylene, polypropylene, and polyvinyl chloride, other animal and vegetable oils, and rubber, and various methods are known for their production. . For example, 2,6-di-t-butylphenol and methyl acrylate may be reacted in t-butanol using potassium hydroxide as a catalyst;
A method is known in which t-butylphenol and an acrylic acid alkyl ester are reacted in dimethyl sulfoxide using potassium hydroxide or sodium hydroxide as a catalyst. However, when using the former method, the reaction yield is low and it is not practical, and when cheap sodium hydroxide is used instead of potassium hydroxide, there are problems such as the reaction does not proceed at all. When using this method, there is a problem that hydrolysis of the produced compound occurs. It is also known to carry out the above reaction in a solution made by reacting, for example, metallic potassium with an excess amount of t-butanol; There is a problem with the manufacturing method. Furthermore, 2.
A method of reacting 6-di-alkylphenol and acrylic acid alkyl ester is also known,
The corresponding 2,6-di-alkyl phenoxide is not used as a catalyst and recovery of the catalyst is required. In addition, when using a metal salt of phenol as a catalyst, the acrylic acid alkyl ester reacts with the metal salt.

It is known that [Formula] is produced as a by-product [J.Amer.Chem.Soc., 68 ,
544 (1946); 69 , 2966 (1947); 72 , 2205
(1950)], this method uses a large amount of metal phenoxide, making the purification process extremely complicated, and furthermore, the reaction temperature is high and an autoclave is required.
There are problems as an industrial manufacturing method. In view of the above, the present inventors have conducted various studies in order to improve these drawbacks and produce the phenols represented by the general formula (2) in an industrially advantageous manner, resulting in the present invention. That is, the present invention is based on the general formula () (In the formula, R ₁ and R ₂ have the same meanings as above.) A phenol compound represented by the formula and an alkali metal hydroxide or an alkaline earth metal hydroxide are reacted in advance at a molar ratio of 1:0.05 to 0.5. After converting a part of the raw material phenol compound into the corresponding metal phenoxide, removing the produced water and making the system substantially anhydrous, the general formula () is added to the system. (In the formula, R ₃ , R ₄ and R ₅ have the same meanings as above.)
This is a method for producing phenols represented by the above general formula (), which comprises adding up to 2 times the amount by mole and causing the reaction. Advantageous features of the present invention are that by using the metal phenoxide of the raw material compound [general formula () compound] as a catalyst, the reaction operation is facilitated, the problem of catalyst recovery is eliminated, and the process can be performed at low temperature, in a short time, and in high yield. The point is to obtain the target compound. Examples of the alkali metal hydroxides used in the present invention include potassium hydroxide and sodium hydroxide, and examples of the alkaline earth metal hydroxides include calcium hydroxide. Further, as the phenol compound represented by the general formula (), for example, 2,6-di-t-butylphenol, 2-methyl-6-t-butylphenol, 2,6-diisopropylphenol, 2-methyl-6- Isopropylphenol, 2-sec-
Butyl-6-t-butylphenol, 2,6-bis(1,1-dimethyl-n-propyl)phenol, 2-methyl-6(1,1,3,3-tetramethyl-n-butyl)phenol, 2.6-di(3
-methyl-n-butyl)phenol, 2-ethyl-6-t-butylphenol, and the like. In addition, as a compound represented by the general formula (),
Examples include acrylic acid alkyl esters, methacrylic acid alkyl esters, crotonic acid alkyl esters, etc., where the alkyl groups include methyl, ethyl, propyl, butyl, amyl, hexyl, heptyl, octyl, and nonyl groups. group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group,
Examples include hexadecyl group, heptadecyl group, nonadecyl group, and eicosyl group. The reaction between the above metal hydroxide and the compound of general formula () is carried out directly or by heating in an organic solvent such as an aliphatic hydrocarbon, an alicyclic hydrocarbon, or an aromatic hydrocarbon. The produced water is removed under reduced pressure or by azeotropic distillation with an organic solvent until the system becomes substantially anhydrous. The desired compound of general formula () is produced by adding the compound of general formula () to the system thus obtained and reacting with the compound of general formula (). The reaction at this time may be performed without a solvent or with a solvent. Can be used. These solvents can also be used in combination with the organic solvent used in the reaction between the metal hydroxide and the compound of general formula (). The reaction temperature is usually 25°C to 200°C, preferably 40 to 120°C.
It may be carried out in a pressurized system. The metal hydroxide is usually used in an amount of 5 to 50 mol % based on the compound of general formula (), and the compound of general formula () is used in an amount of 1 to 2 times the amount of the compound of general formula (). The present invention will be explained below with reference to Examples. Comparative Example 1 51 g of 2,6-di-t-butylphenol, 50 ml of dimethyl sulfoxide and 6 g of potassium hydroxide were placed in a 300 ml four-necked flask, and after replacing the inside of the reactor with nitrogen, 24 g of methyl acrylate was added in 20 minutes. Drop it and keep warm at 60-65℃ for 8 hours. The solvent is then recovered under reduced pressure (20 mmHg, bath temperature 150°C or less). Cool to room temperature, add 120 ml of benzene, and add 50 ml of benzene.
After washing the aqueous layer with ml of water until it becomes neutral, the benzene is distilled off, and the temperature is reduced to 2 mmHg, 140~ by vacuum distillation.
46.1 g (64% of theory) of methyl-β-(3,5-di-t-butyl-4-hydroxyphenyl)propionate was obtained as a fraction at 150°C. Furthermore, 4.2 g (6% of theory) of β-(3,5-di-t-butyl-4-hydroxyphenyl)propionic acid was obtained by acid precipitation of the washing water. This means that in this method, methyl-β-
This shows that hydrolysis of (3,5-di-t-butyl-4-hydroxyphenyl)propionate is occurring. Comparative Example 2 250 ml of dry t-butanol, 1.8 g of potassium hydroxide and 2,6-di-
After charging 18.7 g of t-butylphenol, purging the reactor system with nitrogen, adding 8.9 g of methyl acrylate, and keeping the temperature at 50 to 55°C for 18 hours, the produced methyl-β-(3,5-di- When t-butyl-4-hydroxyphenyl) propionate was measured by gas chromatography, only 6% of the theoretical amount was found to be produced. Comparative example 3 Sodium phenoxide 7.5 in a 200ml flask
After charging 25.5 g of 2,6-di-t-butylphenol and 12 g of methyl acrylate and purging the inside of the reactor with nitrogen, the temperature was raised to cause a reaction. Internal temperature 95
Reflux started around ℃, and the internal temperature reached 110℃ about 4.5 hours after the start of reflux. At this point, methyl-β- produced by gas chromatography
(3,5-di-t-butyl-4-hydroxyphenyl)propionate was measured versus theory 21
It was %. Example 1 41.2 g of 2,6-di-t-butylphenol, 100 ml of n-heptane, and 1.4 g of potassium hydroxide were placed in a 500 ml four-necked flask, and after heating and refluxing for about 1 hour under a nitrogen atmosphere, the product was produced in the system. By removing the water from the reaction system by azeotropy, potassium 2.
2,6- containing 6-di-t-butyl phenoxide
A solution of di-t-butylphenol in n-heptane is obtained. (The water content was 0.01% as measured by the Karl Fischer method) 54 ml of t-butanol was added to this, and methyl acrylate was heated at 80±3°C.
Drop 20.6g. After the completion of dropping, keep warm at 80±3°C for 3 hours under nitrogen atmosphere. It is then neutralized with acetic acid and the water-soluble substances are extracted with water. Thereafter, the solvent was removed under reduced pressure, and the resulting residual material was vacuum distilled to yield 55.6 g (95% of theory) of methyl β-
(3,5-di-t-butyl-4-hydroxyphenyl)propionate is obtained. Example 2 41.2 g of 2,6-di-t-butylphenol and 1.4 g of potassium hydroxide in a 500 ml 4-neck flask
After charging and keeping at 100 to 110°C for 1 hour under nitrogen atmosphere, 100 ml of t-butanol is added and about 60 ml is distilled under normal pressure, and the water produced is removed from the reaction system.
20.6 g of methyl acrylate was added dropwise to this at 80±3°C. After the completion of dropping, keep warm at 80±3°C for 3 hours under nitrogen atmosphere. Then, by carrying out the same treatment as in Example 1, methyl β-(3,5-di-t-butyl-4-hydroxyphenyl)propionate was obtained with a theoretical yield of 95%. Example 3 41.2 g of 2,6-di-t-butylphenol, 100 ml of n-heptane, and 2.0 g of sodium hydroxide were placed in a 500 ml four-necked flask, and after heating under reflux for about 1 hour in a nitrogen atmosphere, By azeotropically removing the produced water from the reaction system, an n-heptane solution of 2,6-di-t-butylphenol containing sodium 2,6-di-t-butylphenoxide is obtained. To this was added 27 ml of t-butanol, and 20.6 g of methyl acrylate was added dropwise at 80±3°C. After completion of dropping, keep warm at 80±3°C for 4 hours under nitrogen atmosphere. Next, by carrying out the same treatment as in Example 1, methyl β-(3,5-di-
t-Butyl-4-hydroxyphenyl)propionate is obtained. Example 4 41.2 g of 2,6-di-t-butylphenol and 1.4 g of potassium hydroxide in a 100 ml 4-necked flask
After charging and maintaining the temperature at 100 to 110° C. for 1 hour under a nitrogen atmosphere, the water produced is removed under reduced pressure to make the reaction system substantially anhydrous. 20.6 g of methyl acrylate was added dropwise to this at 80±3°C. After completion of dropping, keep warm at 80±3°C under nitrogen atmosphere for 4 hours. Then, by carrying out the same treatment as in Example 1, methyl β-(3,5-di-t-butyl-4-hydroxyphenyl)propionate was obtained with a theoretical yield of 80%. Example 5 20.6 g of 2,6-di-t-butylphenol, 100 ml of n-heptane, and 0.7 g of potassium hydroxide were placed in a 300 ml four-necked flask, and after heating under reflux for about 1 hour in a nitrogen atmosphere, Potassium 2.
2,6- containing 6-di-t-butyl phenoxide
A solution of di-t-butylphenol in n-heptane is obtained. Add 27ml of t-butanol to this and
Add 38.9 g of stearyl acrylate at ±3°C and keep warm at 80±3°C for 4 hours under nitrogen atmosphere. After neutralization with acetic acid and extraction of water-soluble substances with water, the solvent is removed under reduced pressure. By recrystallizing the obtained residue from methanol, n-octadecyl β-(3,5-di-t-butyl-4-hydroxyphenyl)propionate was obtained in a theoretical yield of 90%.
It can be obtained with

Claims (1)

[Claims] 1. General formula (In the formula, R ₁ and R ₂ each independently represent a C _1-8 alkyl group.) The phenol compound represented by the formula and the alkali metal hydroxide or alkaline earth metal hydroxide are mixed in a molar ratio of 1: 0.05 to 0.5 to convert a part of the raw material phenol compound into the corresponding metal phenoxide, remove the produced water to make the system substantially anhydrous, and then add the general formula into the system. (In the formula, R ₃ and R ₄ each independently represent a hydrogen atom or an alkyl group, and R ₅ represents a C _1-20 alkyl group.)
A general formula characterized by adding ~2 mole times and reacting (In the formula, R ₁ , R ₂ , R ₃ , R ₄ and R ₅ have the same meanings as above.) A method for producing a phenol.