JPH01313446A - P-dichlorobenzene-benzopinacol clathrate compound, production thereof and method for separating p-dichlorobenzene from p-dichlorobenzene-containing mixture - Google Patents

Abstract

NEW MATERIAL:A clathrate compound of p-dichlorobenzene and benzopinacol containing the p-dichlorobenzene as a guest molecule and the benzopinacol as a host molecule. USE:An intermediate capable of selectively separating p-dichlorobenzene useful as a raw material for mothproofing agents or polyphenylene sulfide resins from a mixture containing the above-mentioned compound, e.g., nuclear isomers of the dichlorobenzene. PREPARATION:p-Dichlorobenzene(PDCB) is brought into contact with benzopinacol(BP) to afford a clathrate compound of PDCB-BP. Furthermore, the PDCB-containing mixture, such as nuclear isomers of the dichlorobenzene, is brought into contact with the BP to form the above-mentioned clathrate compound, which is then separated to further separate the PDCB. Thereby, separation of the PDCB which is conventionally difficult to separate can be efficiently, readily and economically carried out.

Description

[Detailed Description of the Invention] A) Purpose of the Invention [Field of Industrial Application] The present invention provides stable and easy release of para-dichlorobenzene that includes para-dichlorobenzene (hereinafter abbreviated as PDCB) as a guest molecule. The present invention relates to a novel baladiclobenzene-benzopinacol clathrate compound that can be used.

[Conventional technology]

Several clathrate compounds of organic compounds are already known.
For example, 1, 1, 6 with a glycidyl compound as a guest molecule
．． 6-tetraphenylhexer 2,4-diyne-1,6
- Inclusion compound of diol and glycidyl compound (JP-A-62-89674), inclusion compound of 1,1,2,2-tetraphenyl-1,2-niethanediol and picoline with picoline as a guest molecule (Journal of the Chemical Society of Japan, 19B
6.1,927-931), etc.

However, inclusion compounds with PDCB as a guest molecule,
Alternatively, there is no known method for separating PDCB from a PDCB-containing mixture using the clathrate.

PDCB is a useful compound that is widely used as an insect repellent and as a raw material for polyphenylene sulfide resin, which is one of the engineering plastics, and is obtained by the chlorination reaction of benzene or chlorobenzene.

The composition of the reaction product varies depending on the reaction conditions, catalyst, etc., but it is approximately 860 to 90% by weight of PDc, 5 to 40% by weight of orthodichlorobenzene (hereinafter abbreviated as 0DCB), and a trace amount of metadichlorobenzene. (hereinafter abbreviated as MDCB) and trichlorohenzene (hereinafter abbreviated as TCB) are produced (Japanese Patent Publication No. 57-776'31, Japanese Patent Publication No. 57-776'31,
9-163329).

In order to obtain PDCB from this reaction product, there is usually a method of cooling the reaction solution to 10 to -20°C, separating the precipitated PDCB, and purifying the resulting crude PDCB crystals (
Japanese Patent Publication No. 47-40621, Japanese Patent Publication No. 54-20467).

Alternatively, a method of extractive distillation of the reaction solution using an extractant such as dimethyl sulfoxide, sulfolane, cresol, etc.
-174333), a method using an adsorbent such as zeolite or silica (Japanese Patent Application Laid-open No. 58-131924.5B-1
50524), and a method using a eutectic agent such as 1-bromo-4-chlorobenzene (Japanese Patent Laid-Open No. 61-2686)
Various methods have been proposed, such as Publication No. 37).

However, with conventional methods, it has been difficult to efficiently separate and obtain PDCB in high yield.

[Problem to be solved by the invention]

When PDCB is obtained by the chlorination reaction of benzene or chlorobenzene, the reaction solution is cooled to 10 to -20°C and P
In the method of obtaining DCB, since the reaction is usually carried out at 60 to 300°C, in order to increase the amount of PDCB crystals obtained, it is necessary to cool it to below -10°C, which requires a large amount of cooling energy. Economically unfavorable. Furthermore, it is necessary to further purify the obtained crude PDCB using a purification method such as zone melting, which complicates the process.

In addition, in the method of separation by distillation, the boiling point difference between PDCB and 0DCB, which are the main components, is 5.1°C1. Furthermore, the boiling point difference between PDCB and MDCB, which is produced as a by-product during the reaction, is 0.9"CL (for rectification separation). This method requires a rectification device with high efficiency, resulting in high equipment costs and high heat consumption.

Extractive distillation methods have been proposed to compensate for this drawback, but the extractive separation performance is not very good and the safety of the extractant is poor.
Stability etc. becomes a problem.

Furthermore, methods using adsorbents such as zeolite require alternate adsorption and desorption, making the fruiting equipment more than twice as large, and is not economical when physical and chemical losses of the adsorbent are taken into account. It is hard to say that it is a manual input method.

The method using a eutectic agent attempts to perform the above-mentioned cooling crystallization even more efficiently, but the temperature is -10°C or less, which requires a large amount of cooling, which solves the essential problem of the cooling crystallization method. However, this does not solve the problem of energy costs.

The present inventors solved the above problems and conducted various studies on methods for separating and obtaining PDCB efficiently, easily, and economically in a short period of time.
(abbreviated as P) selectively includes PDCB, creating a new P
We have discovered that a DCB-BP clathrate compound is formed, and based on this phenomenon, it is possible to selectively separate and obtain only PDCB from a PDCB-containing mixture, such as a mixture of dichlorobenzene nuclear isomers, etc., in high yield, The invention has been completed.

(1) Structure of the invention [Means for solving the problem] The present invention provides a PDCB-BP clathrate compound in which PDCB is a guest molecule and BP is a host molecule, a method for producing the same, and a PDCB-BP clathrate compound using the clathrate compound. The present invention relates to a method for separating PDCB from a containing mixture.

PDCB, which is a guest molecule in the present invention, may be produced by a conventional method, for example, by a chlorination reaction of penzene or chlorohenzene.

In addition, in the present invention, the PDCB-containing mixture refers to PDCB
For example, nuclear isomers produced as by-products when producing PDCB, i.e. 0DCB, MDC
B or a small amount of by-product TCB may be contained, and any material may be used as long as it does not inhibit inclusion of PDCB or easily desorb PDCB from the generated clathrate compound. The concentration of PDCB in the PDCB-containing mixture is not particularly limited.

The PDCB-BP clathrate compound of the present invention is a combination of PDCB and BP.
produced by contacting

There are various methods for contacting, for example, directly contacting BP with PDCB or a mixture containing PDCB.
Alternatively, they may be mixed or added in the presence of a solvent such as carbon tetrachloride or chloroform.

The blending ratio of PDCB and BP may be determined as appropriate depending on the concentration of PDCB in the PDCB-containing mixture, the solubility of the generated clathrate compound in the solvent when a solvent is used, the desired degree of separation and purification of PDCB, etc. However, BP is preferably 0.5 to 4.0 times mole relative to PDCB, more preferably 1.
It is 5 to 3.0 times the mole. If it is less than 0.5 times the mole, there is a risk that the amount of the desired clathrate compound obtained will be reduced.
If it exceeds 4.0 times the mole, the utilization rate of BP decreases and it can no longer be said to be economical.

The reaction temperature between PDCB and BP is not particularly limited, but is preferably 0 to 100°C, more preferably 10 to 100°C.
It is 60°C. Furthermore, when the reaction is carried out in the presence of a solvent, the produced clathrate may partially dissolve in the solvent, so it is desirable to cool it as much as possible in order to increase the amount of the clathrate obtained. Preferably, this is carried out by cooling to 30°C.

The clathrate compound may be separated from the reaction product by a conventional separation method such as filtration or centrifugation.

The obtained PDCB-BP clathrate compound is PDCB/BP
It is a solid crystal with a molar ratio of 1/2 and can be purified by recrystallization or the like.

The clathrate compound of the present invention can be easily converted into PDC by, for example, distillation.
It can be separated into B and BP.

When separating PDCB by distillation, it is desirable to perform distillation under reduced pressure in order to prevent decomposition of BP, preferably at a distillation temperature of 60 to 170°C, more preferably 70 to 150°C.
°C is good. Below 60°C, the melting point of PDCB is 52°
Since it is C, there is a possibility that evaporated PDCB will solidify in the cooling zone, and if the temperature exceeds 170°C, BP will decompose at 194°C, which may be disadvantageous during recovery and reuse.

PDCB separated by distillation has a high purity of 99% or more, and can be used for various purposes without any further purification.

Further, the distillation residue obtained by distilling off PDCB essentially consists of BP, and can be used as it is again to form the clathrate compound.

[Effect]

Why is only PDCB B in a mixture containing dichlorobenzene?
It forms an inclusion compound with P, but the details are unknown, but BP
Only PDCB is stably incorporated into the crystal of BP.
This is presumed to be due to the formation of new crystals in which PDCB is incorporated into the space while maintaining the crystal structure of .

At this time, it is considered that the difference in the crystal structure of 0DCB, MDCB, and PDCB is largely involved in the formation of an inclusion compound with BP. Whereas PDCB has a melting point of 53°C,
The melting point of 0DCB is -17°C The melting point of 5MDCB is -24
, 8°C, and its structural formula shows that PDCB is 0DCB.
, it is presumed that this is because it has a more symmetrical planar structure compared to MDCB, which is why it is easily incorporated into BP.

Furthermore, the binding force between PDCB and BP in the obtained clathrate compound is easily dissociated by operations such as distillation, and the original PDC
Since it returns to B and BP, it is considered to be a very weak bond.

〔Example〕

The present invention will be specifically explained below with reference to Examples. Note that parts represent parts by weight.

Example I After heating and dissolving 9.9 parts of PDCB, 84.1 part of 0DC, and 50 parts of BP in 300 parts of chloroform, the solution was left at room temperature for 3 days.
The precipitated crystals were filtered to obtain 23 parts of crystals. As a result of infrared absorption spectrum analysis of this crystal, 1470.1390
．． The absorption of PDCB is at 1010.820 cm-', and also at 3050, 1600.1490, 1260.1090
BP absorption was observed at ', 1020 cm-', and OD
No absorption of C'B was observed. Further, as a result of differential thermal analysis of this crystal, it was found that it was a crystal of an clathrate compound with a molar ratio of PDCB and BP of 1/2. The ratio of PDCB to 0DCB in the filtrate from which the crystals were separated was 60/40.

The above crystals were distilled at 110-150°C under reduced pressure to obtain 3 parts of PDCB with a purity of 99.7%.

Example 2 0DC88.8 parts, PDCB8.8 parts, MDC88.8
1 part and 51 parts of BP were mixed at room temperature and left for one day. As a result of analyzing the crystals obtained by suction filtration of 44 parts of the precipitated crystals, it was confirmed that the crystals were crystals of an clathrate compound having a molar ratio of 2 parts of PDCB/BP-1.

c) Effects of the invention The present invention provides a novel PDCB- that selectively includes PDCB.
It is a BP clathrate compound, and by using the clathrate compound, separation of PDCB from PDCB-containing mixtures such as dichlorobenzene nuclear isomer mixtures, which has been difficult in the past, can be efficiently, easily, and economically performed. This makes it possible to obtain PDCB economically.

[Brief explanation of the drawing]

FIG. 1 is an infrared absorption spectrum diagram of the crystal obtained in Example 1, and FIG. 2 is a differential thermal analysis curve diagram of the same crystal.

Claims (1)

[Claims] 1. A paradichlorobenzene-benzopinacol clathrate compound having paradichlorobenzene as a guest molecule and benzopinacol as a host molecule. 2. The method for producing a paradichlorobenzene-benzopinacol clathrate compound according to claim 1, characterized in that paradichlorobenzene and benzopinacol are brought into contact. 3. Contacting the paradichlorobenzene-containing mixture with benzopinacol to produce the paradichlorobenzene according to claim 1.
A method for separating paradichlorobenzene from a paradichlorobenzene-containing mixture, comprising forming a benzopinacol clathrate, separating the clathrate, and separating paradichlorobenzene from the clathrate.