JP2001247493A - Method for producing octafluorocyclopentene - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for industrially advantageously producing high- purity 1,2,3,3,4,4,5,5-octafluorocyclopentene without using any high-purity raw materials. SOLUTION: This method comprises the following two consecutive steps: 1st step: in the presence of a mixed solvent system composed of a polar solvent and nonpolar solvent, a mixture comprising at least two chlorofluorocyclopentenes is reacted with a metal fluoride to fluorinate the mixture, the resultant crude product is distilled to isolate a fraction A comprising 1-chloroheptafluorocyclopentene and a fraction B comprising 1,3and 1,4- dichlorohexafluorocyclopentenes, and 2nd step: the fraction A and/or the fraction B is(are) further reacted with a metal fluoride to effect complete fluorination to obtain the objective 1,2,3,3,4,4,5,5-octafluorocyclopentene.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing octafluorocyclopentene. More specifically, the present invention relates to a method for producing 1,2,3,3,4,4,5,5-octafluorocyclopentene useful as a plasma reaction gas used in the field of semiconductor device production and the like.

[0002]

2. Description of the Related Art Recent VLSI (ultra-integrated circuit), ULS
As seen in the production of ultra-integrated circuits (I), etc., as the integration and performance of semiconductor devices progress, technological demands are also placed on the plasma reaction gas used in the manufacturing process of these devices. There is a growing demand for uniform, high-purity gases.

[0003] By the way, saturated fluorocarbons such as carbon tetrafluoride gas have been mainly used as the plasma reactant gas. However, saturated perfluorocarbons have an extremely long atmospheric life of several thousand years or more, and have a global warming potential. It has been pointed out that this will have a negative effect on biodiversity. From such a viewpoint, various new fluorine-containing compounds have been developed as substitutes.
Among them, 1,2,3,3,4,4,5,5-octafluorocyclopentene (hereinafter sometimes abbreviated as OFCPE), which has an unsaturated bond in the molecule and has an extremely short atmospheric life, It is attracting attention as a very promising plasma reaction gas.

[0004] Such OFCPE is a known substance having a molecular weight of 212 and a boiling point of 27 ° C under normal pressure.
Using N, N-dimethylformamide as a reaction solvent, 1,2
A method of reacting dichlorohexafluorocyclopentene with potassium fluoride is known (U.S. Pat.
24,290 and 3,567,788). However, in this method, the yield is 48-59%.
Therefore, several improved methods for producing OFCPE have been proposed.

For example, in Japanese Patent Application Laid-Open No. 9-95458, potassium fluoride and N, N-dimethylformamide are charged into a reaction vessel equipped with a rectification column, and 1,2-dichlorohexafluoro is added through a dropping funnel. A production method has been proposed in which generated OFCPE is withdrawn from a rectification column while cyclopentene is sequentially dropped. According to this method,
It is described that OFCPE is obtained with a yield of 87.9% and a purity of 99.8%.

[0006] The publication also discloses 1,2,4-trichloro-3,3,4,5,5-pentafluorocyclopentene and 1,2,4,4-tetrachloro-3,3,5,5.
While the mixture of 5-tetrafluorocyclopentene is sequentially dropped from the dropping funnel in the same manner as described above, O
When FCPE is extracted from the rectification column, OFCPE yields 91
% And a purity of 99.98%.

Furthermore, WO 97/43233 discloses a crude product containing four types of chlorofluorocyclopentenes obtained by reacting hexachlorocyclopentadiene with chlorine gas and then hydrogen fluoride in the presence of antimony pentachloride. The product as it is or after rectifying and separating each component, remixed to give 1,2-dichloro-3,3,4,
4,5,5-hexafluorocyclopentene, 1,2,2
3-trichloro-3,4,4,5,5-pentafluorocyclopentene and 1,2,3,5-tetrachloro-
A method for producing OFCPE using a mixture of 3,4,4,5-tetrafluorocyclopentene as a raw material is described.

[0008] In this fluorination method, a method is employed in which the product is extracted out of the reaction system while sequentially adding the raw materials as in the above-mentioned publication, but the yield of OFCPE is 90.5 to 9
It is described as 3.1% and the purity is 99.8 to 99.9%.

[0009]

However, for example, when OFCPE is used as an etching gas for a semiconductor device, it cannot be said that the purity obtained by the above-described conventional manufacturing method is still sufficiently high. In addition, there was room for improvement in the reaction yield. In view of such problems of the related art, an object of the present invention is to provide a method for producing octafluorocyclopentene with extremely high purity in a high yield.

[0010]

Means for Solving the Problems In order to achieve the above object, the present inventors have conducted intensive studies on a method for producing OFCPE, and as a result, have adopted a specific reaction condition without using a raw material having high purity. The present inventors have found that extremely high-purity OFCPE can be obtained with a high yield by performing the above-mentioned steps and performing a specific purification operation, thereby completing the present invention.

Thus, according to the present invention, a mixture of at least two kinds of chlorofluorocyclopentenes represented by the above formula 1 and a metal fluoride are reacted in the presence of a mixed solvent system comprising a polar solvent and a nonpolar solvent. The chlorofluorocyclopentene mixture is fluorinated and the resulting crude product is distilled to obtain a fraction A containing 1-chloroheptafluorocyclopentene and 1,3-dichloro-2,3,3.
A first step of isolating a fraction B containing 4,4,5,5-hexafluorocyclopentene and 1,4-dichloro-2,3,3,4,5,5-hexafluorocyclopentene; 1,2,3,3,4,4 comprising a second step of reacting at least one fraction of fraction A and fraction B with metal fluoride to complete fluorination
A method for producing 5,5-octafluorocyclopentene is provided. The fluorination reaction in the second step is preferably performed in the presence of an aprotic polar solvent.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION First Step (Mixture of Chlorofluorocyclopentene) In the production method of the present invention, a mixture of at least two kinds of chlorofluorocyclopentene represented by the above formula 1 is used as a reaction raw material in the first step. Can be Chlorofluorocyclopentene has a cyclopentene skeleton, and each of two unsaturated bond carbons (positions 1 and 2) has one chlorine atom.
Hydrogen atoms are not bonded to the remaining three saturated bond carbons (positions 3, 4 and 5), and X fluorine atoms (X =
3-6) as long as they are bonded and (6-X) chlorine atoms are bonded.

As such chlorofluorocyclopentene, for example, 1,2-dichloro-3,3,4,4,4
5,5-hexafluorocyclopentene, 1,2,3-
Trichloro-3,4,4,5,5-pentafluorocyclopentene, 1,2,4-trichloro-3,3,4,
5,5-pentafluorocyclopentene, 1,2,3
4-tetrachloro-3,4,5,5-tetrafluorocyclopentene, 1,2,3,3,4-pentachloro-
4,5,5-trifluorocyclopentene and the like.

These chlorofluorocyclopentenes are used as a mixture of two or more. The mixing ratio is not particularly limited, but based on the total weight of the mixture, 1,2-
The content of dichloro-3,3,4,4,5,5-hexafluorocyclopentene is preferably 5 to 95% by weight, more preferably 10 to 93% by weight, and particularly preferably 20 to 90% by weight. The method for producing the raw material mixture is not particularly limited, and for example, it can be produced by a known method using perchlorocyclopentadiene as a starting material.

(Metal Fluoride) Examples of the metal fluoride used in the present invention include fluorides such as alkali metals, alkaline earth metals, and transition metals. Preferably, it is an alkali metal fluoride. Specific examples of the alkali metal fluoride include sodium fluoride, potassium fluoride, lithium fluoride, and cesium fluoride. Of these, potassium fluoride is preferred. These metal fluorides may be used alone or in combination of two or more.

The amount of metal fluoride used is determined by dividing the total (in terms of mole atoms) of the chlorine atoms present in the mixture of chlorofluorocyclopentene used as the raw material by the number of moles of the raw material into the desired product. When a value obtained by subtracting 1 which is the minimum value of the remaining chlorine atoms is taken as 1 equivalent, preferably 1.1 to 2.0 times equivalent, more preferably 1.2 equivalent.
1.5 equivalents.

(Reaction Solvent) It is essential that the reaction solvent used in the first step of the present invention is a mixed solvent of a polar solvent and a non-polar solvent. An aprotic polar solvent is usually used as the polar solvent. Specific examples of such aprotic polar solvents include N, N-dimethylformamide,
N, N-dimethylacetamide, N-methylpyrrolidone, N, N′-dimethylimidazolidinone, dimethylsulfoxide, sulfolane and the like.

As the non-polar solvent, a hydrocarbon solvent compatible with the polar solvent is usually used. Specific examples of such a non-polar solvent include alicyclic hydrocarbons such as cyclopentane, cyclohexane, cyclooctane, and decalin; aromatics such as benzene, toluene, xylene (ortho, meta, para), ethylbenzene, and t-butylbenzene. Although a hydrocarbon etc. are mentioned, an aromatic hydrocarbon is preferable. The combination of the polar solvent and the non-polar solvent is not particularly limited, but a combination of N, N-dimethylformamide and toluene is preferable.

The amount ratio (volume ratio) of the polar solvent and the nonpolar solvent to be used is not particularly limited.
When used as a volume part, the amount of the nonpolar solvent used is usually 0.1.
It is 5 to 1.5 parts by volume, preferably 0.8 to 1.2 parts by volume. If the amount of the nonpolar solvent used is too small, perfluorocyclopentene is easily produced as a by-product. If the amount of the nonpolar solvent used is too large, the reaction rate will decrease.
The amount of the mixed solvent composed of the polar solvent and the non-polar solvent,
Usually 100 to 100 parts by weight of the metal fluoride
It is 1000 parts by weight, preferably 120 to 600 parts by weight, more preferably 150 to 300 parts by weight.

(Fluorination Reaction and Distillation Fractions A and B) The reaction temperature of the fluorination reaction in the first step is 20.
The temperature can be appropriately selected within a range of 50 to 150 ° C.
Is preferable, and 80 to 130 ° C. is more preferable. The reaction time is generally 0.5-30 hours, preferably 2-20 hours. The reaction method and apparatus are not particularly limited, but a batch method or a continuous method in which the raw materials are continuously supplied to the reaction vessel and the reaction product is discharged from the reaction vessel is employed.

When the reaction is carried out in a batch mode, after completion of the reaction, a purification operation is carried out by a distillation apparatus usually used in industry, and a fraction A containing the desired 1-chloroheptafluorocyclopentene (boiling point: 56 ° C.) ) And 1,3-dichloro-2,3,4,4, which is by-produced specifically by the reaction.
5,5-hexafluorocyclopentene and 1,4-
Dichloro-2,3,3,4,5,5-hexafluorocyclopentene (hereinafter, these 1,3-dichloro form and 1,4-dichloro form are collectively referred to as "1,3- and 1,4
-Dichlorohexafluorocyclopentene ") (boiling point about 89 ° C.).

In the case of conducting the reaction in a continuous manner, the reaction is carried out using a reaction vessel equipped with a rectification column while sequentially adding the raw material mixture of the above formula 1 into a reaction solvent in which metal fluoride is dispersed. Is preferred. At this time, the target fraction A of 1-chloroheptafluorocyclopentene and 1,3 which are by-produced specifically by the reaction from the top of the rectification column.
A fraction B containing-and 1,4-dichlorohexafluorocyclopentene can be obtained separately.

As described above, according to the first step of the present invention, 1-chloroheptafluorocyclopentene contained in the intermediate for producing the target product, ie, fraction A, and the compound specifically produced as by-product, ie, fraction B, are contained. 1,3- and 1,
Because the boiling points of 4-dichlorohexafluorocyclopentene differ greatly, they can be isolated separately.

That is, the fractions A and B can be isolated by distillation at a high purity, and other reaction impurities (impurities) can be removed without being mixed into the fractions A and B. Is possible. Further, as described in the second step, not only the fraction A thus isolated but also the fraction B
Can also be used as a raw material in the second step, if necessary.

The material in the second step the second step of the present invention is at least one fraction of the obtained fraction A and fraction B at the first step. Object O
From the viewpoint of the production efficiency of FCPE, it is preferable that the fraction A and the fraction B are mixed and subjected to a fluorination reaction.

The metal fluoride used in the second step is the same as the fluoride used in the first step, but potassium fluoride is preferred. The amount of the metal fluoride to be used is preferably 1.0 to 2.0 equivalents, more preferably 1.05 equivalents, when the number of moles of chlorine atoms contained in the raw material is 1 equivalent.
1.5 equivalents.

The reaction solvent is not particularly limited as long as it is an inert solvent which does not hinder the reaction, but an aprotic polar solvent is preferably used. Specific examples of such aprotic polar solvents include N, N-dimethylformamide, N, N-dimethylacetamide, N-methylpyrrolidone, N, N′-dimethylimidazolidinone, dimethylsulfoxide, sulfolane and the like. These aprotic polar solvents may be used alone or in combination of two or more, but it is preferable to use N, N-dimethylformamide alone or as a main component of the combined solvent system.

The reaction temperature, reaction time, reaction apparatus, reaction method and the like of the fluorination reaction in the second step can be carried out in the same manner as in the fluorination reaction in the first step, but a reaction apparatus equipped with a rectification column It is preferable to extract the target product (OFCPE) from the rectification column while sequentially adding the raw materials to a reaction vessel charged with a metal fluoride and a reaction solvent in advance using the above method. By reducing the residence time of OFCPE in the reaction system by such a method, side reactions such as polymerization of OFCPE can be suppressed.

In this case, the feed rate of the raw material to the reaction system is:
What is necessary is just to set according to the extraction amount of OFCPE. The feed rate (mol / hour) of the raw material is usually 3 times or less, preferably 0.1 to 2 times, more preferably 0.5 to 1.5 times the speed of withdrawing OFCPE. OFCP which is the target
E can be obtained by controlling the temperature at the top of the rectification column. The temperature at the top of the tower can be adjusted by setting the reflux ratio in accordance with the capacity (theoretical plate number) of the rectification column to obtain an OFC.
It can be set near the boiling point of PE. The collection of the target substance, filling of the container, and the like may be performed according to a conventional method, but it is recommended that the operation be performed in an atmosphere of an inert gas such as nitrogen gas, helium gas, or argon gas.

OFCPE produced by the method of the present invention is
It is useful as an etching gas, an ashing gas, and the like in a semiconductor device manufacturing process.

[0031]

EXAMPLES The present invention will be described below in detail with reference to examples, but the scope of the present invention is not limited by these examples. In addition, Hitachi263-70 was used for gas chromatography (GC) analysis. The column is Neutrabon manufactured by GL Sciences.
d Capillary Column (length 60m,
(Inner diameter 2.5 mm). Nitrogen was flowed at a flow rate of 100 ml / min as a carrier gas.

Example 1 Fluorochlorocyclopentene mixture of the first step
Iodination reaction and isolation of fractions A and B : 597.0 g of potassium fluoride in a four-necked flask equipped with a dropping funnel, a rectification column, a thermometer and a stirrer under a nitrogen stream.
(10.3 mol) and a mixture of 480 ml of N, N-dimethylformamide and 720 ml of toluene.
The dropping funnel was charged with 1580.0 g (60.0%) of a raw material mixture composed of 55.5% of 1,2-dichlorohexafluorocyclopentene, 31.4% of trichloropentafluorocyclopentene and 12.5% of tetrachlorotetrafluorocyclopentene. .22 mol). A refrigerant at −10 ° C. was passed through a Dimroth condenser provided at the top of the rectification tower, and a fraction trap cooled to −70 ° C. was connected to the outlet of the condenser.

The flask was immersed in an oil bath and the contents were heated while stirring. After the temperature in the flask rises to 130 ° C, 5
The raw material mixture was added dropwise over time. Two hours after the start of the reaction, the temperature at the top of the rectification column reached the boiling point of the target product (56 ° C.) and became stable. From that time until the temperature at the top of the tower rose to 110 ° C. (about 13 hours from the start of the reaction), the reaction product was intermittently extracted, and as a result, two types of fractions were obtained.

When each fraction was analyzed by GC, the boiling point was 56 ° C.
Was 1-chloroheptafluorocyclopentene (977.1 g, 4.28 mol, yield 68.8).
%). Fraction B having a boiling point of about 89 ° C. is a by-product of 1,3- and 1,4-dichlorohexafluorocyclopentene (2
62.2 g, 1.07 mol, yield 17.2%) and 1,2-dichlorohexafluorocyclopentene (26.6 g, 0.11 mol, recovery rate 1.7%) contained in the raw material mixture. ).

Comparative Example 1 N, N-dimethylformamid was used as a reaction solvent in the first step.
Of chlorofluorocyclopentene mixtures using only
Fluorination reaction and distillation of crude product : Example 1 was repeated except that the entire mixture of N, N-dimethylformamide and toluene used as the reaction solvent in Example 1 was replaced with N, N-dimethylformamide. The reaction and the product were similarly extracted. As a result of GC analysis of the obtained two fractions, 1-chloroheptafluorocyclopentene in the fraction having a boiling point of 56 ° C. was only 33%, and the remainder was located at the third, fourth or fourth position from the GC analysis peak position. It was a mixture of isomers presumed to have substituted one chlorine at the 5-position saturated bond carbon. The fraction having a boiling point of about 89 ° C. was a mixture of many isomers containing 30% of unreacted 1,2-dichlorohexafluorocyclopentene.

Example 2 The distillation operation of the first step and isolation of fractions A and B :
A crude product was drawn out of the reaction system while sequentially adding raw materials in the same manner as in Example 1, except that the rectification column of the reactor of Example 1 was replaced with a simple distillation column. The crude product was purified using a rectification device comprising an oil bath, a glass distillation still, a distillation column with a theoretical plate number of 55 (sluzer type), a cooler, a fraction receiver and the like. A thermocouple thermometer was used to measure and record the temperature of the oil bath, the temperature in the still, and the temperature at the top of the rectification column. A specific distillation operation procedure is shown below.

A single distillation fraction obtained by the same reaction as in Example 1 in the distillation still, that is, octafluorocyclopentene (2.5%), 1-chloroheptafluorocyclopentene (52.8%), 1,3- And 1926.16 g of a mixture having a composition of 1,4-dichlorohexafluorocyclopentene (13.9%) and toluene (14.1%) were charged. The distillation still was attached to a rectification apparatus, immersed in an oil bath and heated to 80 ° C. After the temperature at the top of the rectification tower rose and reached a certain temperature, the whole fraction was refluxed without extracting a fraction for about 2 hours. After that, withdrawal of fraction 3 seconds / reflux 1
A fraction was withdrawn at a reflux ratio of 20 seconds. The temperature in the oil bath and the reflux ratio were changed according to the temperature in the distillation still and the temperature at the top of the rectification column. The component composition ratio of each extracted fraction is represented by G
Table 1 shows the results obtained by the C analysis. F2-5 in Table 1
The main component of (boiling point 56 ° C., fraction A) was 1-chloroheptafluorocyclopentene. The main components of F7-9 (boiling point about 89 ° C., referred to as fraction B) were 1,3 and 1,4-diclohexafluorocyclopentene.

[0038]

[Table 1]

Example 3 Second Step (Synthesis of OFCPE using fraction A of the first step)
Adult): Using the same reaction apparatus as in Example 1, potassium fluoride 27.95 g (0.48 mol reaction vessel) and N, was charged with N- dimethylformamide 100 ml.
In the dropping funnel, the fraction A (F3
100.0 g (0.44 mol). -1 to the Dimroth condenser provided at the top of the rectification tower
A refrigerant at 0 ° C. was flowed, and a fraction trap cooled to −70 ° C. was connected to the outlet of the cooler.

The reaction vessel was immersed in an oil bath and the contents were heated while stirring. After the temperature in the flask rises to 120 ° C, 1
The above-mentioned raw material (fraction A) was continuously dropped over time.
After confirming that the temperature at the top of the rectification column was stabilized at the boiling point (27 ° C.) of the target product, the reaction product was intermittently extracted. As a result of GC analysis of 81.5 g of the product extracted out of the system, the purity of OFCPE was 99.99%.

Example 4 Second Step (Synthesis of OFCPE Using Fraction B of First Step)
Adult): Using the same reaction apparatus as in Example 1, potassium fluoride 50.98g (0.88 mol reaction vessel) and N, was charged with N- dimethylformamide 200 ml.
In the dropping funnel, the fraction B obtained in Example 2 (F8
9 to 98.4 g (0.4 mol). A refrigerant at −10 ° C. was passed through a Dimroth condenser provided at the top of the rectification tower, and a fraction trap cooled to −70 ° C. was connected to the outlet of the condenser.

The reaction vessel was immersed in an oil bath and the contents were heated while stirring. After the temperature in the flask rises to 120 ° C, 1
The above-mentioned raw material (fraction B) was dropped continuously over time.
After confirming that the temperature at the top of the rectification column was stabilized at the boiling point (27 ° C.) of the target product. The reaction product was withdrawn intermittently. As a result of GC analysis of 77.2 g of the product extracted out of the system, the purity of OFCPE was 99.99%.

[0043]

According to the method of the present invention, as a first step, at least two kinds of chlorofluorocyclopentene are reacted with a metal fluoride, and together with 1-chloroheptafluorocyclopentene, 1,3 and 1,4-dichlorohexene are obtained. Although fluorocyclopentene is by-produced specifically, it can be easily purified and isolated as a fraction A and a fraction B by distillation, and other reaction impurities can be removed. Then, as a second step, at least one of these fractions A and B is reacted with a metal fluoride and completely fluorinated.
3,4,4,5,5-octafluorocyclopentene is obtained industrially advantageously.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Toshiro Yamada 1-2-1, Yakko, Kawasaki-ku, Kawasaki-shi, Kanagawa F-term in the Zeon Corporation General Development Center 4H006 AA02 AC30 AD11 BB41 BB42 BD60 BE61 EA15

Claims (2)

[Claims] 1. A mixture of at least two kinds of chlorofluorocyclopentenes represented by the following formula 1 and a metal fluoride in the presence of a mixed solvent system consisting of a polar solvent and a non-polar solvent to form a mixture of the chlorofluorocyclopentene mixture. Fluorination, the crude product obtained is distilled and the fraction A containing 1-chloroheptafluorocyclopentene is obtained.
And 1,3-dichloro-2,3,4,4,5,5-hexafluorocyclopentene and 1,4-dichloro-
A first step of isolating a fraction B containing 2,3,3,4,5,5-hexafluorocyclopentene; and reacting at least one of the fractions A and B with a metal fluoride. 1,2,3,3,4,4,5,5-
A method for producing octafluorocyclopentene. Embedded image (X in Formula 1 is an integer of 3 to 6) 2. The method according to claim 1, wherein the second step is performed in the presence of an aprotic polar solvent.