JPS6075438A - Method for separating 4,4'-dimethyldiphenyl from mixture containing the same - Google Patents

Abstract

PURPOSE:To obtain the titled substance useful as an intermediate for 4,4-diphenyldicarboxylic acid, by bringing a mixture containing 4,4'-dimethyldiphenyl into contact with metacyclophane to form a clathrate compound, and heating the separated clathrate compound, etc. to give the titled substance therefrom. CONSTITUTION:A mixture of dimethyldiphenyls obtained by oxidative dimerization of toluene is brought into contact with metacyclophane of the formula at 20-150 deg.C to give a compound trapping 4,4'-dimethyldiphenyl in the metacyclophane, and the resultant clathrate compound is then separated at 0-90 deg.C by a means, e.g. separation of the solid from a liquid, and then heated to 100-280 deg.C or brought into contact with a solvent, e.g. n-hexane or benzene, to afford the aimed 4,4'-dimethyldiphenyl. The amount of the metacyclophane to be used is preferably 0.05-20mole based on one mole 4,4'-dimethyldiphenyl in the mixture.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for separating 4,41-dimethyldiphenyl from a mixture containing 4,4'-dimethyldiphenyl using metacyclophane represented by the following formula (Il).

For example, 4,4'-dimethyldiphenyl can be converted into H,C-7\I by the reaction shown below using a suitable oxidizing agent.
)CH, +301→nooc()(I3- C0OH+
2H,04.4'-diphenyldicarboxylic acid, and 4.4'-diphenyldicarboxylic acid is disclosed in, for example, JP-A-47-42992 and JP-B-Sho.47-
As stated in Publication No. 2687, it is an important raw material for producing polyester compounds by reacting itself or its dimethyl ester derivatives with various polyols.
Jomon polyester exhibits excellent physical properties such as high heat resistance.

4,4'-dimethyldiphenyl is generally produced by oxidative trimerization of toluene (Chsmlstry & Ind.
industry 457 (1966)).

At this time, various isomers are generated and their boiling points are very close to each other, so it is difficult to separate 4,4'-dimethyldiphenyl by distillation or other operations.
It has been desired to develop an efficient method for separating -dimethyldiphenyl from the above-mentioned isomers.

As a result of intensive research into an effective separation method for such 4,4'-dimethyldiphenyl, the present inventors found that the formula +I)
Metacyclophane expressed as
・4・4′- from a mixture containing 4′-dimethyldiphenyl
The inventors have discovered that it is possible to separate dimethyldiphenyl from other isomers, and have arrived at the present invention.

That is, the present invention provides a clathrate in which 4,4'-dimethyldiphenyl is included in the metacyclophane by contacting the metacyclophane represented by the formula (I) with a mixture containing 4,4'-dimethyldiphenyl. forming a compound, separating the clathrate, and separating the 4,4'-
4 characterized by separating and recovering dimethyldiphenyl
・4・4′ from a mixture containing 4′-dimethyldiphenyl
- A method for separating dimethyldiphenyl.

In the present invention, the metacyclophane contains 4.4
'-Dimethyldiphenyl can be selectively included, and based on this phenomenon, 4,4'-dimethyldiphenyl can be separated from a mixture containing 4,4'-dimethyldiphenyl with high selectivity and high recovery rate. can be done.

The present invention will be explained in detail below.

The metacyclophane in the present invention may be a cyclic compound represented by the above formula (I), and it can be obtained by various production methods. For example, the manufacturing methods include (a) Helvetica, Kimica, Acta (Helv@t1c
a+ ChimieaActa) fi Volume O F, 5c
iculus 7 (1967) A204 (Symtbaslg) 424 (1974) isobarically described.

In the present invention, various methods can be applied to obtain the clathrate compound of metacyclo-77 and 4,4'-dimethyldiphenyl of the general formula (It).

For example, the metacyclophane may be added to a mixture containing 4,4'-dimethyldiphenyl, or the mixture obtained by adding metacyclophane may be added as described above to achieve complete inclusion. It can also be obtained by heating the solution to completely dissolve it, cooling it and separating the resulting crystals.By either method, 4,4'-dimethyldiphenyl is easily included in metacyclophane. Inclusion compounds can be obtained.

The amount of metacyclophane of formula (I) used is 4.4'
o, ooi to 100 mol per mol of 4,4'-dimethyldiphenyl in the monodimethinosidiphenyl-containing mixture,
Preferably 0.01 to 50 mol, especially 0.05 to 20 mol
A 5-molar proportion is advantageous.

When 4,4'-dimethyldiphenyl is included in metacyclophane as described above, generally -50 to 350
'O% preferably θ~200'O.

In particular, it is carried out at a temperature in the range from 20 to 150'O.

In order to separate the clathrate compound thus formed from a mixture containing it, it is usually preferable to use solid-liquid separation (for example, filtration, centrifugation, sedimentation, etc.) or to remove the solvent component by evaporation by distillation. I can do it. In either method, the operating temperature is -50 to 120'O, preferably 0.
A range of ~90'0 is desirable.

In the present invention, the 14,4'-dimethyldiphenyl-containing mixture from which 4,4'-dimethyldiphenyl is separated may be any mixture containing 4,4'-dimethyldiphenyl; Any component other than dimethyldiphenyl may be used as long as it does not inhibit clathration or easily desorb 4,4'-dimethyldiphenyl from the generated clathrate, and in particular, it may dissolve the clathrate easily. It is preferable that the content of 4,4'-dimethylphenyl in the 4,4'-dimethyldiphenyl-containing mixture is extremely low. Since clathrate compounds can be obtained even if
A wide range is fine. For example, when dimethyldiphenyls are used as the 4,4'-dimethylphenyl-containing mixture,
By adding metacyclophane to the mixture and causing clathration, the 4,4' dimethyldiphenyl clathrate compound can be easily separated from the dimethyldiphenyls.

Dimethyldiphenyls refer to compounds having the general formula fill, having one methyl at any of the 2, 3, and 4 positions of the diphenyl nucleus, and 2'.

A general term for compounds having one methyl group at either the 3' or 4' position.

Among these compounds, 3,3'-dimethyldiphenyl and 3,4'-dimethylphenyl are particularly close in boiling point to 4,4'7-1-dimethyldiphenyl, and can be removed by ordinary laboratory precision distillation. However, it is extremely difficult to immediately separate highly pure substances.

However, from the clathrate compound of metacyclophane and 4,4'-dimethyldiphenyl represented by the general formula (II), 44
4,4'-dimethyldiphenyl obtained by separating '-dimethyldiphenyl is of very high purity, almost approaching 100% purity. Metacyclophane+Il has the advantages of not only its performance as described above, but also that it can be synthesized at low cost and that an economical process can be freely selected.

This can be an extremely advantageous process industrially.

The 4,4'-dimethyldiphenyl-containing mixture applicable to the present invention is, for example, the reaction product @ (
(see JOC34p18 (1969)).

Alternatively, a wide variety of 4,4'-dimethyldiphenyl-containing mixtures can be applied, such as a mixture obtained by isomerizing a by-product produced when toluene is oxidized to produce benzyl acetate.

Also, examples: Eva 3,3'-dimethyldiphenyl, 3,4'-
The present invention is particularly suitable for use in processes for producing 4,4'-dimethyldiphenyl by isomerizing dimethyldiphenyl alone or dimethyldiphenyl isomers containing other dimethyldiphenyls using a catalyst such as silica-alumina. sell.

Furthermore, from the clathrate compound of metacyclophane (I) and 4,4'-dimethyldiphenyl, 4,4'-dimethyldiphenyl can be easily desorbed by various methods, resulting in pure 4,4'- Dimethyldiphenyl can be obtained.

In the present invention, metacyclophane + I) h 4・4'
- When separating 4,4'-dimethyldiphenyl from the clathrate with dimethyldiphenyl, various methods are adopted, for example (a) separating the clathrate from 90 to 350
'O, preferably a method for separating 4,4'-dimethyldiphenyl by heating to a temperature in the range of 100 to 280 '0;
(b) In the clathrate compound, for example, n 9- to -? A method of separating 44'-dimethyldiphenyl by bringing it into contact with a solvent such as -111-one, benzene, cyclohexane, a7ton, etc. is advantageously applied.

Next, metacyclophane (Il
The results of various analyzes regarding the clathrate compound obtained by contacting the clathrates are shown below.

+11 Infrared analysis; (a) Metacyclophane (Il characteristic absorption (cm-1)
3050 ~ 2850, 1610, 1590, 1490° 1445.1080, 790, 460° (b) 4.4
'-dimethyldiphenyl; characteristic absorption (6n-') 305
0~2850, 1900, 1640, 1610°156
0.1485, 1445, 1310, 1180°111
5.1035,960,940,835,800°20 (c) Inclusion compound; characteristic absorption (tyn-')305
0-2850, 1610, 1590.150B.

1490.1445,1175,1090,905゜9
00.885-880,850, 840, 795
, 780.

-1〇 - 710.700 (2) Gas chromatography analysis: Analysis by gas chromatography (silicone 0V-1° Anachrome Q carrier, 2m column) revealed that 4. The concentration of 4'-dimethyldiphenyl is 97.3%, and the concentration of 4'-dimethyldiphenyl is almost 4.4%.
'-Dimethyldiphenyl.

(3) Differential thermal analysis: Differential thermal analysis of the clathrate compound showed 94゛0-101'
It showed an endotherm to O. This is an endotherm that neither 4,4'-dimethyldiphenyl nor metacyclophane has. Furthermore, the clathrate compound obtained by contacting only 4,4'-dimethyldiphenyl with metacyclophane +11 and a mixture of 4,4'-dimethyldiphenyl and other isomers are brought into contact with metacyclophane CII K. It exhibited an endotherm at the same temperature as the clathrate compound obtained by this method.

As shown in the examples, the above results demonstrate that even if the 4,4'-dimethyldiphenyl mixture contains one or more components other than 4,4'-dimethyldiphenyl in any proportion, The clathrate compound of the invention is obtained, which shows that 4,4'-dimethyldiphenyl can be selectively included and separated from a 4,4'-dimethyldiphenyl-containing mixture by the use of metacyclophane. It shows that it is possible.

The present invention will be described in detail below with reference to Examples.

In the examples, me indicates metacyclophane, and the selectivity (β) is a value calculated based on the following formula.

Example 1 2.5 parts of 4,41-dimethyldiphenyl and 2.5 parts of metacyclophane were dissolved in 20 parts of m-xylene.
After heating at 0 °C for 30 minutes, 0.1 volume part of m-xylene is removed, and white crystals are precipitated when cooled. Separate the crystals, wash with 30 parts of isopropyl alcohol, and thoroughly dry under reduced pressure. 1.7 parts of white crystals were obtained which showed the same infrared absorption spectrum as above. (m, p,
85-90'O) According to the results of analysis by gas chromatography, this crystal (clathrate compound) was an clathrate compound of metacyclophane and 4,4'-dimethyldiphenyl in a ratio of approximately 1:1. Further, this substance exhibited an endotherm between 94 and 101'O as a result of differential thermal analysis.

Example 2 [4,4'-dimethyldiphenyl and 3,3'-dimethyl] 10 parts of a 1 part 1 mixture of 13-3,3'-dimethyldiphenyl and 4,4'-dimethyldiphenyl and 21 parts of methane and 5 parts of methane Dissolved in 40 parts of m-xylene, heated at 105"0 for 30 minutes, mixed with 20 parts of m-xylene, and cooled to precipitate white plate-like crystals. The crystals were filtered once and washed with 30 parts of isopropyl alcohol. By thoroughly drying under reduced pressure, 5.1 parts of white crystals were obtained.The infrared absorption spectrum of these crystals showed exactly the same absorption as that of the 4,4'-dimethyldiphenyl clathrate, and in differential thermal analysis, also showed an endotherm in exactly the same temperature range.

Furthermore, according to Gascou analysis, 4・4′ in all the clathrate components
The concentration of -dimethyldiphenyl was 97.3% and the selectivity β was 61.9.

Example 3 8.1 parts of 14-4,4'-dimethyldiphenyl clathrate compound were melted by heating and distilled under normal pressure to obtain 1.5 parts of a component distilled at 294-295°0. The infrared absorption spectrum of this substance is exactly the same as that of 44'-dimethyldiphenyl, and gask μ madogram analysis shows that 4.4'
-Identical to dimethyldiphenyl.

Comparative example [3,3'-dimethyldiphenyl inclusion test] 3,3'
-5.0 parts of dimethyldiphenyl and 5.0 parts of metacyclophane.
0 part was dissolved in 40 parts of m-4 silene, heated at 105'O for 30 minutes, mixed with 30 parts of m-xylene, and cooled to precipitate white needle-like crystals. The crystals were filtered, washed with 30 parts of isopropyl alcohol, and thoroughly dried under reduced pressure to obtain 2.5 parts of white crystals. (m, p, 108
~120゛0) The infrared absorption spectrum of this crystal is the same as that of metacyclophane, and differential thermal analysis shows an endotherm at 125-129'O, indicating that it is metacyclophane, not an clathrate. Ta.

Claims (1)

[Scope of Claims] Metacycloane represented by the following formula (II) is brought into contact with a mixture containing 441-dimethyldiphenyl to form an inclusion compound in which the metacyclophane (I) includes 441-dimethyldiphenyl. A method for separating 44'-dimethyldiphenyl from a mixture containing 44'-dimethyldiphenyl, which comprises separating the clathrate and recovering 44'-dimethyldiphenyl from the clathrate.