JPH03167141A - Production of perfluoro compound - Google Patents

Abstract

PURPOSE:To safely obtain the subject substance with hardly any consumption of fluorine by fluorinating a compound having triple bond in the molecule with one or two or more selected from CoF3 AgF2, MnF3 and a complex salt of KF with CoF3. CONSTITUTION:A compound having triple bond in the molecule (preferably acetylene or a compound in which intramolecular hydrogen is substituted with F) is fluorinated with one or two or more selected from CoF3, AgF2, MnF3 and a complex salt (KcoF4) of KF with CoF3 at 250-350 deg.C to afford a perfluoro compound. The resultant perfluoro compound is useful as an etching gas, cleaning gas, vapor-phase insulator, etc., in the semiconductor industry in the case of a gas and as various testing liquids, cooling liquids, etc., in the case of a liquid.

Description

[Detailed description of the invention] Industrial Summer ■Separation The present invention relates to a method for producing perfluorinated compounds.

Perfluorinated compounds have a wide range of uses in the semiconductor industry, such as etching gases, cleaning gases, gas-phase insulators, and leak test agents, when they are gaseous at room temperature, and when they are liquid at room temperature, they are used in the semiconductor industry. It has uses such as various test liquids and cooling liquids, and both are industrially important compounds.

の　′　That.

The production of a perfluoro compound will be explained below using the production of hexafluoroethane as an example.

Methods for producing hexafluoroethane include (1) a direct fluorination method in which fluorine gas is used to react with ethane, (2) an electrolytic fluorination method using ethane and/or ethylene as raw materials,
(3) Pyrolysis method of thermally decomposing tetrafluoroethylene, etc., (4
) There is a method of fluorinating ethane and/or ethylene using a metal fluoride. However, since the method (1) above uses highly reactive fluorine gas, there is a risk of explosion and corrosion, and a reactor with a special structure must be used. In order to suppress side reactions such as cutting and polymerization, it is necessary to coexist with a large amount of inert gas. Method (2) involves many side reactions and has problems in separation and purification of the product, while method (3) requires high temperatures for the reaction and has a low yield.

In addition, method (4) is shown in the reaction formula: When ethane is used as a raw material, C! )16 + 12CoFff→CzF* + 6H
P + 12CoFz, and the by-product Coat is fluorinated with fluorine gas, converted to CoF, and reused.

That is, 12CoPz +6Fz −' 12COF3
In addition, when using ethylene as a raw material, CzHa + 10COF3 - C2F4 + 4
8F + 10CoFz10CoFz+5F2-+
As is clear from the reaction formula of 0 or more which is 10CoF3,
When using ethane as a raw material, 6 moles of fluorine are required per mole of ethane, and when using ethylene as a raw material, 5 moles of fluorine are required per mole of ethylene.0The heat of reaction is proportional to the number of moles of fluorine; The greater the amount, the greater the reaction heat. As a result, carbon-carbon bonds are easily broken and explosions occur.
This results in a decrease in yield and poses a problem in industrial operations. In addition, fluorine is usually acidic potassium fluoride (KP・21
1F) is produced by molten salt electrolysis, and is expensive due to high electricity and steam costs. Therefore, it is desirable that the amount of fluorine used be as small as possible.

An object of the present invention is to reduce the amount of fluorine consumed and to produce perfluorinated compounds safely and efficiently.

The present invention uses compounds with triple bonds in their molecules such as cobalt trifluoride (CoFs), silver difluoride (^gh), manganese trifluoride (MnF3), and potassium fluoride and cobalt trifluoride. This is a method for producing a perfluoro compound, characterized by fluorination with one or a mixture of two or more of complex salts (CoF4).

Compounds with triple bonds in the molecule include acetylene,
In addition to hydrocarbons such as methylacetylene, 2-butyne, methylethylacetylene, and 4-methyl-2-pentyne, compounds in which part or all of hydrogen is replaced with fluorine, such as CHECP, ChCEC)l, CFsCmiCCF ,,C
PsC=CCH2, CtFsC=CH:(CH3)s
CCmiCP, refers to compounds such as H(CFg)sCmiC(CFt)sH In the present invention, particularly favorable results are obtained when acetylene or a compound in which hydrogen in its molecule is replaced with fluorine is used as a raw material. can get.

The reaction formula for producing hexafluoroethane according to the present invention is as follows.

C*Hg+8CoFs →' CzPh+2HF+8C
oFx8CoFz+ 4Fz -8CoF.

In other words, it is only necessary to use 4 moles of fluorine gas per 1 mole of acetylene, the reaction heat can be easily controlled, and it has great industrial utility value.The reason why this method has not been implemented or suggested in the past is probably that Although this is probably due to the strong awareness of the dangers of oxidation and the tendency for triple bonds to break, the method of the present invention makes it possible to safely obtain the desired perfluorinated compound in a high yield.

The preferred reaction temperature in the present invention is 150 to 400°C, particularly preferably 250 to 350°C.

EXAMPLE 1 The contents of the present invention will be explained in more detail by showing examples below.

555 kg of CoP was charged into a reactor made of nickel and heated to 300°C in a nitrogen stream, and then acetylene gas was heated to 8°C.
The reaction product gas fed at a flow rate of 00 d/min was passed through an alkali washing tower in which a 10% aqueous potassium hydroxide solution was circulated.
After removing hydrogen fluoride, the composition was analyzed by gas chromatography.

The reaction continued for 2 hours and analysis was performed at 20 minute intervals.
The average gas composition was as follows.

CF, 1.8% (area percentage, same below)
clp, 98.1% Others 0.1% CF4 is thought to be formed by cleavage of C-C bonds, but the cleavage of C-C bonds is estimated to be 0.9%.

Next, after passing nitrogen into the reactor and cooling it to 200°C, fluorine gas was introduced at a flow rate of 5 Fz to convert Cod into CoF.
After the conversion was completed, the fluorine gas in the reactor was replaced with nitrogen while the temperature was raised to 300°C, and acetylene gas was again fed at a flow rate of 800 d/min.

The reaction gas was analyzed as before and almost identical values were obtained.

1 ship 11 The temperature of the reactor used in Example 1 was set at 220°C, and acetylene gas was fed at a flow rate of 300 InlZ.

As a result of analysis in the same manner as in Example 1, the average gas composition was as follows.

CP, 0.2% C2F,
97.4% CHF, CP, and CHFz
CHPz 1.3% Others 1.1
% Actual difference When 50 kg of MnF+ was charged into the reactor used in Example 1 and a reaction was carried out under the same conditions as in Example 1, the average gas composition was as follows.

CF4 1.9% CzF6 97.0% Others 1.1% 1 kg of AgF was placed in a nickel reactor (diameter 5.3 cm and length 100 cm), and acetylene gas was heated to 50 m 1Z at 250'C. Fluorination was carried out by feeding at a flow rate.

When analyzed in the same manner as in Example 1, the average gas composition was as follows.

CF4 0.2% C2F, 96.3% Others 3.5% AgF was used in the reactor used in Fuwao Example 4, and CaF was used instead of AgF.
2 was charged, and the reaction and analysis were carried out in the same manner as in Example 4, and the average gas composition was as follows.

CF, 0.2% CzFa 95.9% Others 3.9% The temperature of the reactor used in Example 1 was set at 300°C,
Next, ethane gas (CH3CH3) was introduced at a flow rate of 800 d/min.The calorific value of the reaction was large and 20 minutes after the start of the reaction, 4
The analysis of the zero reaction gas that had risen to 60°C revealed the following.

CFa 31.2% Cff1F, 53.6% Others 15.2% Next, when ethylene gas (CH3CH3) was fluorinated under the same conditions, the temperature was 425°C 30 minutes after the start of the reaction.
The zero reactant gases that rose to 0 were as follows:

CF4 17.9% C2F4 64.6% Others 17.5% It can be seen that in these cases, the amount of CF4 produced is large and the cleavage of the C--C bond is greater than in the case of acetylene.

Claims (1)

[Claims] 1. Compounds with triple bonds in the molecule include cobalt trifluoride (CoF_3), silver difluoride (AgF_2), manganese trifluoride (MnF_3), and a composite salt of potassium fluoride and cobalt trifluoride (KCoF_4). 1. A method for producing a perfluoro compound, which comprises fluorinating with one or a mixture of two or more of the following.