JP2000281599A - Production of 1,4-bis(chlorodifluoromethyl)benzene - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a 1,4-bis(chlorodifluoromethyl)benzene useful as an intermediate for medicaments and agrochemicals, raw materials for functional substances or the like in a good yield by the chlorination of a bis(difluoromethyl)benzene with chlorine in the presence of a radical polymerization initiator. SOLUTION: By the chlorination of 1 mol, 1,4-bis(difluoromethyl)benzene with >=2 mol supply chlorine in the presence of (preferably 0.00001-0.05 mol) radical polymerization initiator at preferably the reaction temperature of 0-120 deg.C and the reaction pressure of 1-3 kg/cm2. The radical polymerization initiator is preferably an azo-based initiator (e.g. azobisisobutyronitrile or the like). The reaction may be carried out in the presence of a solvent (e.g. carbon tetrachloride or the like) and a reactor having lining made of glass, stainless steel or the like is employed as the reaction zone. The contacting method may be e.g. flow-through-type, batch-type or the like. The obtained compound can be purified by distillation or the like to impart a high purity product.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing 1,4-bischlorodifluoromethylbenzene, which is useful as an intermediate for medical and agricultural chemicals, a raw material for functional substances, and the like.

[0002]

2. Description of the Related Art Parylene polymer has been attracting attention as a dielectric film material used in the field of electronic components and optical components because of its high dielectric constant and high melting point. Parylene polymers are obtained by chemical vapor deposition (CVD) of parylene dimers. Among the parylenes, poly α, α, α ',
α′-Tetrahalogenopallylene, particularly polyα, α, α ′, α′-tetrafluoroparylene, in which halogen is fluorine, is a particularly desirable substance in which both the dielectric constant and the melting point are higher than those of other halogen polymers. .

[0003] α, α, α ', α'-tetrafluoroparylene dimer (octafluoro- [2,2] paracyclophane) is obtained by dehydrogenating 1,4-bistetrafluorobenzene or its halogen-substituted product. It is known that it can be obtained by dehalogenating and dimerizing.

Literature (J. Org. Chem. Vol. 35 (No. 1) 20-22 (197
In (0), 1,4-bischlorodifluoromethylbenzene is a mercury lamp that passes chlorine gas at a reflux temperature to 1,4-bisdifluoromethylbenzene dissolved in carbon tetrachloride and passes Pyrex glass (TM) there. Is described.

[0005]

While the photochlorination process is a process suitable for producing limited quantities, the present invention provides a process that is more industrially suitable for mass production.

[0006]

The present inventors have studied means for solving the above-mentioned problems.
-The presence of a specific initiator in the reaction system comprising bisdifluoromethylbenzene and chlorine allows 1,4
It was found that -bischlorodifluoromethylbenzene was formed, and the present invention was reached.

That is, the present invention is a method for producing 1,4-bischlorodifluoromethylbenzene, comprising chlorinating 1,4-bisdifluoromethylbenzene with chlorine in the presence of a radical initiator.

[0008] 1,4-bisdifluoromethylbenzene may be produced by any method.
For example, a method of obtaining 1,4-bistrifluoromethylbenzene by fluorinating 1,4-bisdibromomethylbenzene with antimony trifluoride under the condition of no solvent at 100 to 150 ° C. and 20 to 100 mmHg is known. (Chemical abstract, 124, 11684
8).

A method of fluorinating terephthalaldehyde with sulfur tetrafluoride at 150 ° C. (J. Am. Chem. Soc,
82 543 1960) and a method of fluorinating with molybdenum fluoride and boron trifluoride (French Patent No. 2109416).

A method of fluorinating 1,4-bisdichloromethylbenzene obtained by chlorinating para-xylene with a metal fluoride (WO 98/24743) is known. And conditions for reacting with KF in a slurry state have been proposed.

Further, a method for fluorinating 1,4-bisdichloromethylbenzene with hydrogen fluoride has been filed by the present applicant (Japanese Patent Application No. 10-333014).

The chlorination reaction of the present invention is carried out by contacting chlorine in a reaction zone. As the reaction region, a reaction vessel lined with glass, stainless steel, iron, glass, fluororesin, or the like is employed. 1,4-
The method of contacting bisdifluoromethylbenzene with chlorine is not particularly limited, and can be carried out by a flow system, a batch system, or a semi-batch system. To give an example, it is common and preferable to blow chlorine gas into 1,4-bisdifluoromethylbenzene charged in a reaction vessel in advance.

To advance the reaction, a radical initiator, for example, an azo compound such as azobisisobutyronitrile and azobisvaleronitrile, benzoyl peroxide, dodecanoyl peroxide, dilauroyl peroxide, t-butylperoxypi An azo compound is preferred, using a radical initiator such as a peroxide such as valate. The amount of the radical initiator used is 0.000001 to 0.1 mol based on 1 mol of 1,4-bisdifluoromethylbenzene,
0001-0.05 mol is preferred. The initiator can be charged in a required amount at the start of the reaction, but it is preferable to add the initiator sequentially with the progress of the reaction in terms of controlling the reaction.

The reaction temperature varies depending on the type of initiator used, but is about 0 to 120 ° C., preferably 40 to 100 ° C. If the temperature is lower than 0 ° C., the reaction hardly proceeds. Since the chlorination reaction is exothermic, the reaction temperature can be adjusted by externally heating or cooling and changing the chlorine introduction rate or by diluting the chlorine gas with an inert gas, for example, nitrogen, argon, helium, or the like. it can. Since the reaction pressure has little effect on the reaction, it is not necessary to particularly apply pressure, and it is usually 0.5 to 10 kg / cm ² ,
It can be performed at 3 kg / cm ² .

The amount of chlorine used in the reaction may be at least 2 moles per mole of 1,4-bisdifluoromethylbenzene, but is about 2 to 4 moles to optimize the reactor or reaction operation. By this, it can be about 2 mol. Optimization is performed by setting reaction conditions such as temperature and raw material ratio, and since the chlorination reaction is a gas-liquid contact reaction, conventional means for increasing the contact efficiency, such as a stirrer, a gas blowing device, and a spar Use of jars,
Alternatively, it is effective to appropriately employ a method using a multi-stage chlorination reactor.

The method of the present invention can be carried out in the presence of a solvent. The solvent used is capable of dissolving the raw materials and the product, is an inert solvent in the chlorination reaction, and preferably has a sufficient boiling point difference with the product, for example, carbon tetrachloride, chloroform, Tetrachloroethane, monochlorobenzene, o-, m-, p
-Dichlorobenzene, trichlorobenzene, monobromobenzene, dibromobenzene, 2,3-, 2,4-,
Examples thereof include 2,5-, 2,6-, 3,4-, 3,5-dichlorobenzotrifluoride, 3,4,5-trichlorobenzotrifluoride, and bistrifluoromethylbenzene.

The 1,4-bischlorodifluoromethylbenzene obtained by the chlorination reaction according to the present invention can be made into a high-purity product by ordinary purification treatment such as distillation.

Hereinafter, the present invention will be described in detail with reference to examples, but embodiments of the present invention are not limited thereto. The percentage in the examples represents the area percentage of the gas chromatograph unless otherwise specified.

[0019]

EXAMPLES Example 1 A reflux condenser was attached to a 50 ml three-necked flask, 20.0 g of 1,4-bisdifluoromethylbenzene was charged, and nitrogen gas was slowly blown in while stirring to start heating. When the temperature of the reaction solution reached 60 ° C., the introduction of nitrogen gas was stopped, and 38 mg of 2,2′-azobisbutyronitrile (AIBN) was added.
Minutes later, the supply of chlorine gas was started. This time is defined as the start of the reaction. Gas exiting the reactor was discharged through a water trap and then an aqueous caustic soda trap. Reaction temperature 6
While maintaining the temperature at 0 to 80 ° C., 37 mg of AIBN was added every 2 hours, and the reaction was continued for 4 hours. Thereafter, the introduction of chlorine gas was stopped, and nitrogen gas was introduced to cool the reactor to room temperature.

The content of the reactor was 26.8 g, and analysis by gas chromatography revealed that 1,4-bischlorodifluoromethylbenzene was 99.4%.

[0021]

According to the method of the present invention, 1,4-bischlorodifluoromethylbenzene can be produced from 1,4-bisdifluoromethylbenzene in a simple manner with a high yield.
This is advantageous as an industrial production method.

Claims (3)

[Claims] 1. A process for producing 1,4-bischlorodifluoromethylbenzene, comprising chlorinating 1,4-bisdifluoromethylbenzene with chlorine in the presence of a radical initiator. 2. The method for producing 1,4-bischlorodifluoromethylbenzene according to claim 1, wherein the radical initiator is an azo-based initiator. 3. A reaction temperature of 0 to 1 in the presence of a radical initiator.
The production of 1,4-bischlorodifluoromethylbenzene according to any one of claims 1 to 2, comprising supplying 2 mol or more of chlorine to 1 mol of 1,4-bisdifluoromethylbenzene at 20 ° C to cause a reaction. Method.