JPH01246229A - Separation of 4,4'-diisopropylbiphenyl - Google Patents

Abstract

PURPOSE:To obtain the subject compound from a mixed stock liquid produced by the alkylation of biphenyl, in high yield and purity, advantageously from the viewpoints of industry and economy, by adding a solvent to a mixed feed oil containing more than specific amount of the subject compound and cooling the mixture, thereby selectively crystallizing the subject compound. CONSTITUTION:A mixed stock liquid containing >=15wt.%, preferably 25-70wt.% of 4,4'-diisopropylbiphenyl (4,4'-DIPBP) is mixed with a solvent such as 1-4C aliphatic alcohols and/or 6-8C paraffins, preferably 1-4C aliphatic alcohols. The amount of the solvent is 50-500 pts.wt. per 100 pts.wt. of the mixed stock oil when the 4,4'-DIPBP-content of the mixed stock oil is 15-70wt.%. The obtained mixture is cooled to crystallize and separate the 4,4'-DIPBP useful as an intermediate for 4,4'-dicarboxybiphenyl (a raw material for novel polymer), in high efficiency at a low cost.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for separating 4,4°-diisopropylbiphenyl from a raw material mixture oil obtained by an alkylation reaction of biphenyl.

[Prior Art] 4.4゛-diisopropylbiphenyl is a compound useful as a raw material for the production of 7-dicarboxylic polymers, and is also a compound useful as an intermediate for the production of 4,4°-dicarboxyhyphenyl. is.

As the alkylation reaction of biphenyl, a method of reacting it with propylene in the presence of an aluminum chloride catalyst or a solid acid catalyst, and a method of transalkylating it with a polyisopropyl compound such as polyinpropylbenzene are generally known.

The composition of the reaction mixture obtained by these reactions is monoisopropylbiphenyl (hereinafter referred to as IPBP),
Diisopropylbiphenyl (hereinafter referred to as DIPBP)
Approximately 30 types of compounds have been detected in gas chromatography analysis, including triisopropylbiphenyl (hereinafter referred to as TIPBP) and unreacted hiphenyl, and many diisopropyl-substituted biphenyls. gastric bodies have been detected. and 4,4°- in such a reaction mixture.
The content of DIPBP is usually as low as 1-5% by weight.

Therefore, the present inventors conducted precision distillation of the reaction mixture obtained in the alkylation reaction of biphenyl to produce 4,4゛-DIPB.
We attempted to isolate P, but it was difficult to separate and remove 3,4°-DIPBP and 3.5,3°-TIPBP.
It has proven difficult to isolate 4,4°-DIRBP by distillation alone.

That is, 3,4°-DIPBP is 4.4'-D I
It is a component that distills out just before PBP, and it is a component that distills out just before PBP.
I PBP is a component distilled immediately after 4.4'-D I PBP. If it is attempted to completely separate and remove these, the loss of the target product, 4,4°-DIPBP, will increase, and a higher number of plates in the distillation column, a higher reflux ratio, etc. will be required, resulting in a significant increase in cost.

[Problems to be Solved by the Invention] As a result of further intensive research into a method for efficiently separating 4,4°-DIPBP from the reaction mixture of biphenyl alkylation reaction, the present inventor discovered that biphenyl alkylation Obtained by distillation of the reaction mixture, 4.4'-D
The present invention was completed by discovering that 4,4°-DIPBP selectively crystallizes by cooling a raw material mixed oil containing 15% by weight or more of I PBP.

Therefore, an object of the present invention is to separate 4,4°-DIPBP from a mixed oil containing 4,4°-DIPBP obtained by biphenyl alkylation reaction with high purity and high yield, and at low cost. The purpose is to provide a way to obtain

[Means for Solving the Problems] That is, the present invention involves the separation of 4,4°-DIPBP by adding a solvent to a raw material mixed oil containing 15% or more of 4,4°-DIPBP and crystallizing it by cooling. It's a method.

In the method of the present invention, the raw material mixed oil containing 15% or more of 4,4°-DIPBP can be used, for example, by isopropylating biphenyl using propylene in the presence of an aluminum chloride catalyst or a solid acid catalyst, or by chlorinating biphenyl. A reaction mixture obtained by a conventionally known alkylation reaction, such as a method of transisopropylating biphenyl and a polyisopropyl compound such as polyisopropylbenzene in the presence of an aluminum catalyst or a solid acid catalyst, is concentrated by an appropriate means such as distillation. of which 4.4'-[)I
15% by weight or more of PBP, preferably 25 to 70 weight ω
%. 4,4°− in this raw material mixed oil
If the DIPBP content is lower than 15% by weight, crystallization will cause
．． It is difficult to separate 4'-DIPBP.

In addition, the following conditions should be met for the solvent added to such raw material mixed oil: (1) It must have a low freezing point, preferably below -30'C, (2) It must have a low viscosity and will crystallize after cooling. , 4'-D I P
B The solubility of 4,4°-DIPBP is low, and the solubility is 15 g/100 g or less at the solid-liquid separation temperature of BP, preferably 10 c, p or less. , preferably less than 5 g/1009, ■4,4°-DIP
It has high compatibility with alkylated biphenyl products other than BP, and a state of complete dissolution is more preferable, but even if liquid-liquid separation occurs, it can be uniformly dispersed by stirring and has the effect of lowering the apparent viscosity; ■From an industrial standpoint, it is preferable to use a material that satisfies the following requirements: low toxicity, low cost, versatility, and easy disposal, recovery, and reuse. Examples of solvents that satisfy these conditions include aliphatic alcohols having 1 to 4 carbon atoms and paraffins having 6 to 8 carbon atoms, preferably aliphatic alcohols having 1 to 4 carbon atoms. . Regarding these solvents, only one type can be used alone, and
It can also be used as a mixed solvent in which two or more types are mixed.

In the method of the present invention, such a solvent addition is an essential condition.

That is, when the solid-liquid equilibrium of the raw material mixed oil containing 15% by weight or more of the above 4.4-DI RBP was measured, -5
4.4°-DI from the raw mixed oil even when cooled to °C.
Only PBP crystallizes, but the viscosity of this raw material mixture oil rapidly increases as the temperature decreases, and the crystals and mother liquor form a viscous thriller state, even if solid-liquid separation by suction filtration or centrifugation is not possible. Even if solid-liquid separation is carried out for a long time using a highly efficient separation means, the solid phase becomes a paste, making further separation of the mother liquor difficult. However, in order to improve the recovery rate of the target product 4,4'-D I PBP, the cooling temperature of the raw mixed oil and the temperature during solid-liquid separation must be adjusted within an industrially and economically possible range. Even if the raw material mixture oil with a low content of 4,4°-DIPBP is used as a raw material, this 4.4'-D I
It is desirable to recover PBP. This problem may have been solved by the addition of solvent HO. By adding a solvent during the cooling crystallization of the raw material mixture oil, even if the temperature during cold comb 11 and solid-liquid separation is lowered, it is still industrially solid. This enables liquid separation.

Regarding the amount of solvent used for this purpose, does it vary depending on the 4,4°-DIPBP content in the raw mixed oil?4. ! The content of l'-D I RBP is 15 to 70
In terms of weight percent, the solvent is 50 to 500 parts by weight per 100 parts by weight of the raw mixed oil. If the amount of solvent used is less than 50 parts by weight, it will not be effective in reducing the viscosity of the raw mixed oil, and if it is more than 500 parts by weight, the amount of processing will increase, resulting in problems such as larger equipment and increased cooling costs. This is economically disadvantageous.

After adding a solvent to the raw material mixed oil and performing solid-liquid separation by cooling and crystallization, the resulting 4,4°-D I PBP crystals can be further washed with an appropriate solvent to remove the adhesion to the crystals. Removal of the mother liquor improves the purity of 4,4°-DTPBP. The cleaning solvent used for this purpose can be selected based on the same criteria as the solid-liquid separation solvent used for the purpose of solid-liquid separation, and even if it is the same as this solid-liquid separation solvent,
Alternatively, they may be different. Further, the operating temperature of this cleaning solvent is preferably the same as that of the solid-liquid separation solvent, or higher than the operating temperature of the solid-liquid separation solvent within a range of 10'C or less. Generally, the amount of cleaning solvent to be used is preferably about 0.5 to 5 times the weight of the mother liquor or the attached crystals.

Furthermore, in order to obtain high-purity 4.4'-D I RBP, the same solvent as that used for solid-liquid separation is used for the cooling crystallization operation and solvent washing operation performed after adding the above-mentioned solvent. It may be possible to combine the recrystallization operation using a suitable solvent.

The number of recrystallization operations depends on the composition of the raw material mixture oil used as raw material,
Cooling temperature during crystallization, required 4,4°-DIPBP
Depending on the purity, etc., by effectively incorporating a solvent washing operation, it is possible to increase the purity in a small number of times. By combining these purification operations, 4.4'-D I P
The purity of BP can be easily increased to 99% or more.

[Example 1] Hereinafter, the method of the present invention will be specifically explained with reference to Examples.

Example 1 1,380 ffi parts of biphenyl and 3,640 parts by weight of triisopropylbenzene were reacted at 200° C. for 0.5 hour in the presence of an acidic catalyst and with stirring.

After the reaction is completed, the catalyst is separated into solid and liquid, and further distilled to remove the benzene ring compound to obtain 2.040 parts (q) of reaction product oil.The composition of this reaction product oil is determined by gas chromatography analysis. , biphenyl or 2% by weight, IPBPh)1
8% by weight, 52% by weight of DIPBP, 22% by weight of TIPBP
% by weight and 6% by weight of other compounds. Also, D
The proportion of each isomer in IPBP is 3.5 monomer at 14%,
3,3゛ one piece is 30%, 3,4 degree one piece is 39%, 4,4
'Integrated was 13% and other was 4%.

This reaction product oil was roughly distilled to obtain 180 parts by weight of raw material mixed oil. The composition of this raw material mixed oil was determined by 3. /l'-D I RBP is 26% by weight, 4.4'-D I PB P is 48% by weight, D I
PBP was 14% by weight and others were 122% by weight.

Next, 100 parts by weight of the raw material mixed oil thus obtained and 100 ffl parts of isopropanol (as a solvent) were charged into a container equipped with a stirrer and stirred to form a uniform solution.

Then, while stirring, the temperature of this solution was gradually lowered to -30
Stirring was continued for 1 hour at 'C to precipitate crystals, solid-liquid separation was carried out while maintaining this cooling temperature, and the solid phase was washed with isopropanol at -30'C and dried to obtain a purity of 99% by weight. 38 crystals of 4.4'-DIPBP were obtained. The recovery rate of 4,4°-DIRBP at this time was 78% by weight. The results are summarized in Table 1.

Examples 2 to 4 As shown in Table 1, -F Separation of 4,4°-DIPBP was carried out in the same manner as in the above example. The results are shown in Table 1.

Comparative Example 1 4,4'-DIPBP48% deuterium in the same container as Example 1
100 parts by weight of raw material mixed oil containing the following were charged, gradually cooled while stirring, and stirring was continued at 5° C. for 1 hour. The contents of the container were in the form of a viscous slurry.

'The contents of this container were subjected to solid-liquid separation in the same manner as in Example 1, resulting in 28 parts by weight of 4,4°-DIPBP crystals with a purity of 85% by weight (recovery rate of 51% by weight).

Comparative Example 2 4. Same as Comparative Example 1 except that the cooling temperature was 0°C.
An attempt was made to separate 4'-DIPBP. In Comparative Example 2, the contents of the container became a very viscous slurry, and solid-liquid separation took a long time and was not easy.

Comparative Example 3 4.4'-DI RBP Using the raw material mixed oil with a P content of 10% by weight as it was, 4.4° was prepared in the same manner as in Example 1.
- A separation operation of DIPBP was performed. In the case of Comparative Example 3, no crystal precipitation was observed.

[Effects of the Invention] According to the method of the present invention, 4,4°-DIPBP can be produced with high purity and high yield from the mixed oil obtained by the alkylation reaction of biphenyl, while still being industrially and economically efficient. can be advantageously separated.

Patent applicant: Nippon Steel Chemical Co., Ltd.

Claims (2)

[Claims] (1) A method for separating 4,4'-diisopropylbiphenyl, which comprises adding a solvent to a raw material mixed oil containing 15% by weight or more of 4,4'-diisopropylbiphenyl, and crystallizing it by cooling. (2) Claim 1 in which an aliphatic alcohol having 1 to 4 carbon atoms and/or a paraffin having 6 to 8 carbon atoms is used as the solvent.
The method for separating 4,4'-diisopropylbiphenyl as described.