JPH0460457B2 - - Google Patents

Description

Detailed Description of the Invention The present invention uses 2,6-di-t-butylphenol (hereinafter abbreviated as 26B) as a starting material, and uses 3,5,
Through 3′,5′-tetra-t-butyldiphenoquinone (hereinafter abbreviated as TBDPQ) and 3,5,3′,5′-tetra-t-butylbiphenol (hereinafter abbreviated as TBBP), p , p'-biphenol.

In recent years, p,p'-biphenol has been in the spotlight as a raw material for engineering plastics, particularly as a raw material for heat-resistant resins, and demand is expected to increase in the future. By the way, regarding the method for producing p,p'-biphenol from 26B as a starting material,
According to what is described in known literature, the method generally consists of the following three steps.

First step: Oxidation coupling of 26B
Get TBDPQ.

Second step: TBDPQ is reduced or reacted with 26B to obtain TBBP.

Third step: TBBP is debutylated in the presence of a catalyst to obtain p,p'-biphenol.

Regarding the first and second steps above, J.Org.
Chem. 22 1439 (1957) oxidized 26B in t-butyl alcohol (hereinafter abbreviated as t-BuOH) by blowing oxygen into it in the presence of a caustic potash catalyst to produce TBDPQ, and the resulting crude TBDPQ was A method is disclosed in which purified TBDPQ is obtained by recrystallization from ethanol, which is dissolved in ethanol again, reduced with sodium dithionite, and filtered after cooling to obtain TBBP. However, this method requires easy stirring because the TBDPQ obtained by blowing oxygen is poorly soluble in t-BuOH, and as the oxidation progresses, the reaction mixture becomes a viscous slurry. A large amount of t-BuOH is required for tightening.
In addition, the TBDPQ mentioned above is dispersed in t-BuOH as fine particles, and it is extremely difficult to recover it with high purity through filtration. There is a disadvantage that it must be subjected to a reduction reaction (second step) after separation and purification.

On the other hand, Japanese Patent Publication No. 44-25077 teaches a method for obtaining TBBP by subjecting the TBDPQ produced in the first step to the second step without isolating it. In this method, in the first step, 26B is
% to synthesize TBDPQ, and then reacted with the remaining 26B as shown in the following formula.
A method for producing TBBP by such a reaction operation is also described in Japanese Patent Publication No. 102-1972.

These methods are similar to the aforementioned J.Org.Chem., 22 1439 in that the first and second steps can be performed in the same reactor.
(1957), but it has the disadvantage that the yield of TBBP is low because it is difficult to completely react the theoretical amount of 26B with TBDPQ in the second step. By the way, in Example 2 of Japanese Patent Publication No. 44-25077, the yield of TBBP is only 63%.

As a result of extensive research into the reaction conditions of the first and second steps, the present inventors found that the reaction rate of 26B was increased by 20 to 50%, rather than reacting 26B to 50% in the first step as in the conventional method. It is better to keep the amount of unreacted 26B at around 40% and actively leave it, and then react this remaining 26B with TBDPQ in the second step to reduce TBBP.
was found to be obtained with a high yield of 70-90%. This is a new fact not taught in known literature, and is one of the features of the present invention.

Regarding the third step, when debutylating the TBBP produced in the second step,
Publication No. 42-102 discloses that debutylation is carried out by heating to 240 to 280°C using aluminum isopropoxide as a catalyst, and U.S. Patent No. 3,631,208 discloses that biphenols are used as a solvent for debutylation. It is proposed that. However, since the melting point of p,p'-biphenol is extremely high at 280°C or higher, it is not only quite difficult to find phenols as high-boiling point solvents suitable for this, but also when phenols are used as a solvent. ,
Transalkylation may also occur. Regarding this point, Shida and Kawahara, members of the present inventors, previously proposed in the invention of Japanese Patent Application No. 130345/1987 that diphenyl ether is extremely suitable as a solvent for debutylation of TBBP. did. The present inventors further developed this, and obtained in the second step
If diphenyl ether is used as a solvent for debutylation of TBBP, it has a low viscosity at room temperature and is chemically stable, so it can be used to remove butylation from the oxidative coupling reaction in the first step to the debutylation in the third step. It has been found that the processes up to the chemical reaction can be carried out in a liquid phase state, and that the process for producing p,p'-biphenol can be greatly streamlined. During debutylation, diphenyl ether may be partially butylated to become mono, di, tri-t-butyl diphenyl ether, but such mixed diphenyl ether is also liquid at room temperature and cannot be debutylated. Can be used as a solvent.

Therefore, the method for producing p,p'-biphenol according to the present invention includes (a) bringing 26B into contact with an oxygen-containing gas in a t-BuOH solvent in the presence of a caustic potassium (KOH) catalyst to perform an oxidative coupling reaction. 20 of 26B
~40% is converted to TBDPQ, and (b) the resulting reaction mixture is heated to evaporate the solvent while reacting the 26B remaining in the reaction mixture with TBDPQ to form TBBP.
After producing 26B, unreacted 26B is distilled off under reduced pressure to recover a bottom liquid containing TBBP as the main component, and (c) this bottom liquid is converted into one or more diphenyl ethers. The method is characterized in that it is dissolved and the insoluble catalyst is filtered off, and the resulting filtrate is added with a debutylation catalyst and heated to perform debutylation.

To explain one specific example of carrying out the present invention, an alkali metal hydroxide can be used as a catalyst in the oxidation coupling reaction in the first step, but KOH is the most suitable among them. . Although various solvents can be used as the solvent, t-BuOH is most suitable because it does not produce by-products and is stable against oxidation. t-
There is no need to strictly control the moisture content of BuOH;
Azeotropic fraction recovered by distillation (purity 85-88
%) can be used as is. Therefore, during the actual preparation, 85% t-BuOH was used as the solvent.
to which the molar ratio of KOH/26B is 0.01~
26B with KOH to be 0.5, preferably 0.1-0.2
dissolve. Next, the liquid temperature is maintained at about 50° C., and an oxidation coupling reaction is carried out for a certain period of time while blowing an oxygen-containing gas, typically air, at a constant rate. Of course, the oxygen-containing gas may be oxygen gas itself. When the oxidative coupling reaction is carried out until the conversion rate of 26B reaches 20-40%,
A reaction solution containing about 10-20% TBDPQ is obtained.

This reaction solution is gradually heated to distill off the water-containing t-BuOH, and further heated to bring the temperature of the solution to about 200℃.
By the reaction between 26B and TBDPQ by raising the temperature to
Complete the generation of TBBP. Thereafter, this reaction solution is subjected to vacuum distillation under conditions of a pressure of 30 to 10 mmHg and a temperature of 180 to 200°C, and this is continued until distillation of unreacted 26B is completed to obtain a bottom liquid containing TBBP as a main component.

Without cooling this bottom liquid, add an appropriate amount of diphenyl ethers and filter it as it is at 80 to 130°C, or add at least one of acid clay, diatomaceous earth, and activated carbon to remove tar and catalyze it. Filter together with KOH. The amount of diphenyl ethers used is at least 0.5 times the weight of the bottom liquid,
In particular, it is preferably 1 to 2 times the weight. The filtrate is a clear yellow liquid. The filtration residue is washed with an appropriate amount of diphenyl ethers, and the washing liquid and the previous filtrate are combined. Next, as a debutylation catalyst, for example, p-toluenesulfonic acid is added to this at a concentration of 0.01 to TBBP.
~10% by weight, preferably 0.1-3% by weight,
Heat with stirring to 200-300℃, preferably
Raise the temperature to 240-260°C and perform debutylation. Sulfuric acid, benzenesulfonic acids, aluminum phenoxides, aluminum alkoxides, etc. can also be used as debutylation catalysts, but p-toluenesulfonic acid is preferred because it is easily available and does not require catalyst filtration. Optimal. Isobutylene generated during debutylation is discharged from the system via a backflow condenser. After maintaining the predetermined temperature until the generation of isobutylene has almost stopped, the reaction solution is cooled to precipitate p,p'-biphenol, which is filtered to obtain a filter cake. When this cake is washed with a small amount of toluene and dried, highly purified p,p'-biphenol with a purity of over 99% can be obtained as pure white crystals. The yield is 75-90% of theory based on the consumed 26B.

As is clear from what has been described above, in the conventional method for producing p,p'-biphenol,
While operations such as removing the catalyst by neutralizing water washing, washing the isolated intermediate product with a solvent, or recrystallizing it are necessary, the present invention does not require these operations at all, and is also free from troublesome wastewater treatment. Ru.
Therefore, the present invention has extremely great industrial significance in that it can streamline the entire process for producing p,p'-biphenol.

The present invention will be specifically explained below with reference to Examples, but the present invention is not limited to these Examples.

Example 1 26B309g in a four-necked flask equipped with stirrer, thermometer, air blowing pipe and backflow condenser
(1.5 mol), 85% t-BuOH 309g, 48% KOH 17.5
(0.15 mol, KOH/26B molar ratio 0.1) was charged and dissolved, the liquid temperature was maintained at 49-51°C, and air was blown out at 300 c.c./
The reaction was carried out for 4 hours by blowing at a rate of min. 639.7g of the obtained reaction solution had a TBDPQ of 11.4% (26B conversion rate).
23.9 mol%) and was in the form of a slurry. This was then heated to 200° C. over 1 hour and 40 minutes, during which time 325.7 g of water-containing t-BuOH was recovered and, at the same time, TBDPQ was converted to TBBP by reaction with 26B. The bottom liquid containing TBBP obtained here was reduced to 30 to 10 mmHg in an inert gas stream, and the liquid temperature was
The mixture was treated at 180 to 200°C until no unreacted 26B was distilled out, yielding 86.2 g of recovered 26B. Add 180 g of diphenyl ether to 225 g of the remaining liquid (crystal precipitation temperature 185 °C) and dissolve at 190 °C.
The mixture was cooled to 90°C, filtered and the residue was washed with 45g of hot diphenyl ether. 34.3 g of waste catalyst and 415.3 g of filtration and washing liquid were obtained. Add p-toluenesulfonic acid to this filtrate and washing liquid.
0.45g (0.2% by weight of TBBP) was added and the temperature was raised from 129°C to 250°C with stirring for 5 hours, during which time 103.1g of isobutylene generated in the debutylation reaction was pumped into the system via a backflow condenser. It was discharged outside. 250℃ until the generation of isobutylene stops.
The reaction solution was cooled and filtered. The filtered crystals were washed with 80 g of toluene and dried, p.
76.1 g of p'-biphenol was obtained. This was a shiny white crystal with a purity of 99.5% and a melting point of 281.5-282.7°C. The yield was 75.6% versus theory.

Example 2 Into the same apparatus as in Example 1, 309 g (1.5 mol) of 26B,
Recovery 85% t-BuOH 309g, 48% KOH 17.5g (0.15
mol, KOH/26B molar ratio 0.1) and dissolve it, keep the liquid temperature at 49 to 52℃ and air at 300c.c./min.
Oxidation is carried out by blowing at a rate of 6 hours,
641.7 g of a slurry oxidation reaction solution containing 17.38% TBDPQ (26B conversion rate 36.3 mol%) was obtained. This was heated to 200℃ over 1 hour and 40 minutes, and 85% t-
293.5 g of BuOH and 29.5 g of distilled water were also distilled. During this process, the reaction progressed and the bottom liquid was produced.
Contains TBBP and unreacted 26B, crystal precipitation temperature 138
It was warm at ℃. This is carried out at a pressure of 30~ in an inert gas stream.
Vacuum distillation was performed under conditions of 10 mmHg and a temperature of 180 to 200°C to recover 70.8 g of unreacted 26B. The residual liquid is heated to 190℃.
After adding 370 g of diphenyl ether, the mixture was cooled to 100° C., 7.4 g of acid clay (3% by weight to TBBP) was added, treated at 100 to 105° C. for 30 minutes, and then filtered while hot. The cake was washed with 40 g of hot diphenyl ether to obtain 30.3 g of spent catalyst KOH and 630 g of filtrate and washing liquid. The crystal precipitation temperature of this product was 77 DEG C., and it was treated in the same manner as in Example 1 to obtain 93.2 g of p,p'-biphenol as pure white crystals. Melting point 281-282.5℃, purity 99.3%.
The yield was 86.6% vs. 26B theory.

Example 3 The procedure was carried out in exactly the same manner as in Example 2 except that activated carbon was used instead of acid clay, and as pure white crystals p,
86.7 g of p'-biphenol was obtained. Melting point 281.5~282.5
℃, and the purity was 99.4%. The yield was 84.55% vs. 26B theory.

Example 4 Mixed diphenyl ethers including butylated diphenyl ether produced during the debutylation reaction (14% diphenyl ether, 43% mono t-butyl diphenyl ether, 43% di t-butyl diphenyl ether)
The reaction was carried out in exactly the same manner as in Example 1, except that %) was used as the solvent, and 74.3 g of p,p'-biphenol was obtained. The melting point was 281-282.3°C, and the yield was 75.2% versus the theoretical value.

Claims (1)

[Claims] 1 (a) 2,6-di-t-butylphenol is brought into contact with oxygen or an oxygen-containing gas in the presence of a caustic potash catalyst in a t-butyl alcohol solvent to remove 20 to 40% of the 2,6-di-t-butylphenol. 3,5,3',5'-tetra-t-butyldiphenoquinone, and (b) heating the resulting reaction mixture to distill off the solvent while removing the 2,6-diphenoquinone remaining in the reaction mixture. -t
- reacting butylphenol with 3,5,3',5'-tetra-t-butyldiphenoquinone,
After producing 5,3',5'-tetra-t-butylbiphenol, unreacted 2,6-di-t-butylphenol is distilled off under reduced pressure to produce 3,5,3', A bottom liquid containing 5'-tetra-t-butylbiphenol as a main component is collected, and (c) the obtained bottom liquid is dissolved in one or more diphenyl ethers and the undissolved catalyst is filtered out. A method for producing p,p'-biphenol, which comprises separating the filtrate, adding a debutylation catalyst to the obtained filtrate, and heating to perform debutylation. 2. The method according to claim 1, wherein the diphenyl ether used in step (c) comprises a butylated diphenyl ether. 3. The method according to claim 1, wherein the catalyst is filtered out by adding at least one of acid clay, diatomaceous earth, and activated carbon to the diphenyl ether dispersion liquid of the bottom liquid.