JPS6232184B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to the general formula () (In the formula, R ₁ and R ₂ are each independently a hydrogen atom, R ₃ is a C ₁ to ₈ alkyl group, R ₄ is each independently a hydrogen atom and an alkyl group, and R ₅ is a C ₁ to This invention relates to an improved method for producing phenols represented by ₍₂₀ alkyl groups).

Phenols represented by the general formula () are useful as stabilizers for many organic compounds such as lubricating oils, fuel oils, animal or vegetable oils, waxes, soaps, greases, gasoline, rubbers, and resins, and their production Various methods are also known.

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, for example, reacting metallic potassium with an excess amount of t-butanol, but in this case, an expensive and dangerous metal is used, so There was a problem with the manufacturing method.

Under these circumstances, the present inventors conducted various studies to improve these drawbacks and produce the compound of the general formula () industrially advantageously, and as a result, they arrived at the present invention.

That is, in the present invention, an excess amount of an aliphatic alcohol having 1 to 8 carbon atoms is reacted in advance with an alkali metal hydroxide or an alkaline earth metal hydroxide (hereinafter simply referred to as metal hydroxide), and the resulting water is is removed to make the system substantially anhydrous, and then the general formula () (However, R ₁ and R ₂ have the same meaning as above)
Compounds and general formulas shown by () (However, R ₃ , R ₄ and R ₅ have the same meanings as above.) This is a method for producing a compound represented by the above general formula (), which comprises reacting the compound represented by the following.

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.

Aliphatic alcohols or alicyclic alcohols having 1 to 18 carbon atoms (hereinafter simply referred to as alcohols) include methyl alcohol, ethyl alcohol, n
-Propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, sec-butyl alcohol, t-butyl alcohol, n-amyl alcohol, isoamyl alcohol, sec-amyl alcohol, diethyl carbinol, t-amyl alcohol, n-hexyl Alcohol, methyl amyl alcohol, methyl ethyl carbinol, 3-heptanol, dimethyl pentanol, n-octyl alcohol, sec-octyl alcohol, ethylhexyl alcohol isooctyl alcohol, n-nonyl alcohol,
Diisobutylcarbinol, n-decyl alcohol, undecanol, dodecanol, tridecanol, tetradecanol, pentadecanol, hexadecanol, heptadecanol, octadecanol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol , dipropylene glycol, butylene glycol, etc., and tertiary alcohols are particularly preferably used.

In addition, examples of the compound represented by the general formula () include phenol, ortho-cresol, metacresol, para-cresol, 2,6-di-t-
Butylphenol, 3-methyl-6-t-butylphenol, 4-methyl-6-t-butylphenol, 2,4-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, etc.

In addition, as a compound represented by the general formula (),
Examples include acrylic acid alkyl ester, methacrylic acid alkyl ester, and crotonic acid alkyl ester, where the alkyl group is a methyl group,
Ethyl group, propyl group, butyl group, amyl group, hexyl group, heptyl group, octyl group, nonyl group,
Examples include decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, nonadecyl group, and eicosyl group.

The reaction between the metal hydroxide and the alcohol is usually carried out in a large excess of the alcohol, preferably by heating and refluxing under a nitrogen atmosphere, and the water produced in the reaction is entrained with the excess alcohol,
Alternatively, it is removed by azeotropic distillation until the inside of the system becomes substantially anhydrous. At this time, the alcohol is not completely distilled off, but a portion thereof remains and is used as a reaction solvent in the next reaction.

The catalyst system thus obtained has the general formula ()
By adding and (), the desired compound of general formula () is produced. The reaction at this time is usually 25°C to 200°C (under pressure), preferably 40°C to 200°C.
The reaction temperature is carried out at 120°C, but the reaction temperature varies depending on the type of alcohol used and the boiling point of the compound of general formula ().

In this reaction, the compound of general formula () is added in advance to the reaction system of the metal hydroxide and the alcohol, and after the reaction is completed, the system is made into a substantially anhydrous state, and then added to the reaction system. It is also possible to add a compound of general formula (), and this method can be said to be industrially advantageous.

Here, the metal hydroxide is usually used in an amount of 5 to 50 mol% based on the general formula () compound, and the general formula () compound is used in an amount of 1 to 50 mol% based on the general formula () compound.
2 moles are used. The amount of alcohol used is not particularly limited, and is the sum of the amount consumed in the reaction with the metal hydroxide, the amount consumed in removing the produced water, and the amount required as a reaction solvent.

The present invention will be explained below with reference to Examples.

Example 1 200ml of t-butanol in a 300ml 4-necked flask,
1.4 g of potassium hydroxide and 41.2 g of 2,6-
After adding di-t-butylphenol and heating under reflux for about 1 hour in a nitrogen atmosphere, 120 ml of the solvent is distilled off to make the reaction system substantially anhydrous. It was 0.01% when measured by the method). Then 80±
20.6 g of methyl acrylate was added dropwise at 3°C, and after the addition was completed, the mixture was kept at 80±3°C for 3 hours in a nitrogen atmosphere.

Neutralize the catalyst with 35% hydrochloric acid and recover the solvent by distillation. Vacuum distillation of the residual substance obtained yields 2mm
54.4g of Hg as a fraction of 140-150℃ (vs. theory 93
%) of methyl β-(3,5-di-t-butyl-4
-hydroxyphenyl) propionate is obtained.

Example 2 In a 300 ml four-necked flask, 200 ml of t-butanol, 1.4 g of potassium hydroxide, and 41.2 g of 2,
After adding 6-di-t-butylphenol and heating under reflux in a nitrogen atmosphere for about 1 hour, 120 ml of the solvent is distilled off to make the reaction system substantially anhydrous. Then 70g of stearyl acrylate at 80±3℃
is added dropwise in a molten state, and after the completion of dropping, the mixture is kept at 80±3°C for 3 hours in a nitrogen atmosphere.

Neutralize with 35% hydrochloric acid and recover the solvent by distillation. By recrystallizing the obtained residual substance from methanol, stearyl β-(3,5-di-t-
95.5 g (90% of theory) of butyl-4-hydroxyphenyl) propionate are obtained.

Example 3 By carrying out the same operation as in Example 1 using 2.0 g of sodium hydroxide, 49.7 g of methyl β-
(3,5-di-t-butyl-4-hydroxyphenyl)propionate (85% of theory) is obtained.

Example 4 By using 32.8 g of 3-methyl-6-t-butylphenol in the method of Example 1, the yield was increased.
Methyl β-(3,5-di-t-butyl-2) at 68%
-hydroxyphenyl) propionate is obtained.

Comparative Example 1 250 ml of dry t-butanol, 1.8 g of potassium hydroxide, and 18.7 g of 2,6-di-t-butylphenol were placed in a 500 ml four-necked flask, and after purging the inside of the reactor with nitrogen, methyl acrylate was added. Add 8.9g and keep warm at 50-55℃ for 18 hours.

The produced methyl β-(3,5-di-t-butyl-4-hydroxyphenyl)propionate was measured by gas chromatography, and the results were as follows: Theory 6
Only % of the production was observed.

Comparative Example 2 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 4-necked flask, and after replacing the inside of the reactor with nitrogen, 24 g of methyl acrylate was added dropwise over 20 minutes. 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, wash with 50 ml of water until the aqueous layer becomes neutral, and then distill off the benzene.
Distilled under reduced pressure as a 2mmHg140-150℃ fraction
46.1 g (64% of theory) of methyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate was obtained.

In addition, by acid precipitation of the washing water, 4.2g (6% of theory) of β-(3,5-di-t-butyl-4
-Hydroxyphenyl)propionic acid is obtained,
In this method, methyl β-(3,5-di-
It was confirmed that hydrolysis of t-butyl-4-hydroxyphenyl)propionate had occurred.

Claims (1)

[Scope of Claims] 1. An excess amount of an aliphatic alcohol having 1 to 8 carbon atoms is reacted with an alkali metal hydroxide or an alkaline earth metal hydroxide in advance, and the produced water is removed to substantially eliminate the inside of the system. After the system is brought to an anhydrous state, the general formula (In the formula, R ₁ and R ₂ each independently represent a hydrogen atom or a C ₁ to C ₈ alkyl group.) (In the formula, R ₃ and R ₄ are each independently a hydrogen atom or an alkyl group, and R ₅ is a C ₁ to C ₂₀ alkyl group.) general formula to (In the formula, R ₁ , R ₂ , R ₃ , R ₄ and R ₅ are the same as above.) A method for producing a phenol represented by the following.