JPS617273A - Production of perfluoro-1,2-ethanesultone - Google Patents

Abstract

PURPOSE:To carry out the reaction of tetrafluoroethylene with sulfur trioxide for the production of the titled substance, preventing the explosion hazard, by diluting the reaction system with a diluent gas at a specific dilution ratio. CONSTITUTION:The compound of formula (sultone) is produced by the reaction of CF2=CF2 with SO3. The reaction is carried out by diluting the reaction system with a diluent gas at a volume ratio Z of the gaseous phase of <0.6 and keeping the ratio X of SO3 in the gaseous phase (SO3+sultone+diluent gas) to <=Y (=0.16+0.067Z). The diluent gas is tetrafluoroethylene used as a reaction material or an inert gas (preferably N2 gas). The ratio X of SO3 can be maintained to <=Y by introducing SO3 and CF2=CF2 into the reaction system containing the objective sultone. USE:Synthetic raw material or synthetic intermediate for various functional fluorine compounds.

Description

Detailed Description of the Invention [Industrial Field of Application] Concerning the method for producing monoethane sultone, more specifically, a specific reaction method of tetrafluoroethylene (CF2 = CF2) and sulfur trioxide (SO3) is used to reduce the explosive range. The present invention relates to a new method for producing perfluoro-1,2-ethane sultone that avoids the above problems and enables industrially safe and reliable operation.

[Prior Art] Perfluoro-1,2-nitane sultone (hereinafter sometimes abbreviated as sultone) is a difunctional compound that can be easily and quantitatively analyzed in the presence of a base such as triethylamine. It can be rearranged to FOC-CF2-9O2F,
It is known to be useful as a synthetic raw material or synthetic intermediate for various functional fluorine compounds. See, eg, US Pat. No. 2,852,554. It has also been known for a long time that such nulltons can be produced in good yields by the reaction of CF2'4;F2 and S03.

The above-mentioned U.S. Patent No. 2,852,554 and U.S. Patent No. 3
See the specification of No. 16311t56, etc.

In the method for producing sultone by the reaction of CF2 = CF2 and S03, freshly distilled anhydrous S03 is usually charged into a pressure-resistant reactor, and CF, = GF2 are continuously introduced therein under pressure to start the reaction system. The temperature is 80'C! Generally, an operation is adopted in which the reaction is allowed to occur while maintaining the temperature below (cooling as it is an exothermic reaction). In such conventional reaction operations, the desired sultone can be obtained almost quantitatively by continuing the reaction until absorption of CF2=CF2 stops.

[Problems to be Solved by the Invention] There is a report that a violent explosion once occurred in the method for producing sultone by the reaction of CF2=CF2 and S03 as described in -1-2. In this report, the raw material S0
3 and the product sultone are unstable and prone to explosion over a wide range of mixing ratios, especially at l:l mixing ratios, and the presence of ignition sources or overheating must be avoided. has been pointed out.

The mixture of raw material SO3 and product sultone is especially l:
The fact that it is easy to explode when the mixture ratio is 1 leads to the following serious problems in industrial implementation. In other words, in the process of producing sultone as the reaction progresses,
The mixing ratio of S03 and sultone falls within the above-mentioned explosive range, resulting in the danger of explosion. Although it is possible to adopt a reaction device that can avoid the presence of ignition sources and overheating, the fact that the reaction process always passes through the explosion range is disadvantageous for industrial implementation due to the danger of unexpected accidents. .

Means for Solving Problem 1 The present invention has been made to solve the above-mentioned problem, and in a method for producing tons by the reaction of CF2=CF2 and S03, the above reaction is carried out using tetrafluoroethylene and non-fluoroethylene. The reaction is carried out with or without dilution with at least one kind of diluent gas selected from the group consisting of active gases, and the dilution ratio Z of the gas phase portion of the reaction system by the diluent gas is less than 0.6, and the reaction is carried out with or without dilution. By keeping the proportion X of S03 in the gas phase part of the system below Y,
The present invention provides a new method for producing perfluoro-1,2-ethane sultone, which is characterized by carrying out a reaction between 2=CF2 and SO3. However, in the above, and Y is 0.16+0.0872.

The present invention was completed based on the discovery of the following fact. That is, the boiling points of S03 and sultone are close to each other, 46°C for the former and 42°C for the latter, and the composition ratios of S03 and sultone in the liquid phase part and the gaseous phase part of the reaction system are close to each other. In the gas phase part! Therefore, if explosion in the gas phase of the reaction system is prevented,
Explosion of the entire reaction system can be effectively prevented.

According to the research of the present inventor, when diluting the reaction system to a certain value or more with an appropriate diluent gas, even if the presence of an ignition source or overheating is not avoided, all of S03 and sultone are Although no explosion occurs at all mixing ratios, if no dilution or dilution ratio is less than a specific value, the explosion can be effectively prevented by keeping the proportion of S03 in the gas phase of the reaction system below a specific value. We have discovered that this can be prevented.

In the present invention, the reaction between CF2 = CF and S03 is carried out with or without dilution with a specific diluent gas. As the diluent gas, an inert gas that is inert to tetrafluoroethylene, which is a reaction raw material in the present invention, and the reaction raw materials and products in the present invention may be employed. Examples of the inert gas that can be employed in the present invention include nitrogen gas, carbon gas, argon gas, and helium gas, but nitrogen gas can be preferably employed in industrial implementation. The dilution ratio Z of the reaction system in the present invention is the volume ratio of the diluent gas based on the total amount of SulfI, S03, and diluent gas present in the gas phase portion of the reaction system, that is, it is full.

In the present invention, the ratio X of S03 based on the total amount of sultone, S03, and diluent gas in the gas phase portion of the reaction system is maintained at a specific value Y or less shown in CF2=CF2 and S0
It is important to carry out reaction 3. The specific value Y is 0.18+'0.0, corresponding to the above dilution ratio Z.
872. For example, when carrying out the reaction without dilution, the specific value Y is 0.16, and the proportion of S03
When carrying out the reaction with a dilution ratio Z of 0.16 or less and a dilution ratio Z of 0.5, the specific value Y will be approximately 0.19, and the proportion X of S03 will be selected from a value of approximately 0.18 or less. etc.

In the present invention, as long as the configuration described in item 2 is satisfied, a wide range of conventionally known or well-known conditions can be appropriately adopted as other reaction conditions and operations. For example, the reaction temperature is usually preferably about 25 to 80°C, and the reaction pressure is usually about 0 to 3 kg/'cvdG. Also, CF2 = CF2 and S0
The reaction molar ratio of 3 is not particularly limited and can be adopted over a wide range, for example, the reaction molar ratio of S to the target product sultone
C in a reactor in which sultone and S03 are charged at a predetermined ratio so that the ratio of 03 is within the range of the specified value specified in
0F2=CF2 and S03 are introduced into a reactor in which F2=CF2 is continuously introduced or sultone is charged in advance.
can be introduced continuously at an appropriate feeding speed.

The reaction between CF2 = CF2 and S03 proceeds at a high reaction rate and almost quantitatively, but since it is an exothermic reaction, it is usually carried out under cooling in order to suppress the rapid rise in temperature within the reaction system. desirable. Furthermore, it is desirable to avoid the introduction of water into the reaction system, as this may cause undesirable side reactions. The reaction in the present invention does not particularly require the use of a catalyst or reaction medium, but an inert medium may be used as appropriate, if necessary.

In the present invention, explosion can be effectively avoided by maintaining the ratio of S03 in the reaction system below a specific value and carrying out the reaction between OF, = CF2 and 903. In the reaction operation, it is preferable to make the target substance sultone exist in the reaction system in advance, and to introduce S03 and CF2=CF2 therein. Thus, by controlling the rate of introduction of S03, it is possible to always carry out the reaction with the abundance ratio of 503 below a specific value. Such a reaction operation can naturally be carried out in a batch manner, but it can also be easily carried out as a continuous process. For example, a bubble column type reactor is filled with sultone in advance, CF2 = CF2 and S03 are continuously introduced from the bottom of the reactor and reacted while being moved to the L section of the reactor, and the remaining sultone is introduced from the top of the reactor. A continuous process is possible in which the mostly O sultone of S03 is continuously extracted.

[Example] Next, an uninvented example will be explained in more detail, but it goes without saying that the present invention is not limited to this explanation in any way.

Cylindrical container (wall thickness: 5 mm) made of heat-resistant glass (product name: "Pyrex") with an inner diameter of 120 iI 1 mφ and a height of 100 + am
) A sealed tank explosion limit measuring device was assembled in which the lower part of the tank was sandwiched between polypropylene thick plates (10 cm thick). A hole with a diameter of 90 mm is bored in the upper thick plate, and the chain hole is closed with a movable plate made of polypropylene acid. A stirrer for uniform gas mixing, a thermometer, and two electrodes for providing an ignition source are installed inside the tank.

After thoroughly evacuating the inside of the container using a vacuum pump,
S03. Sulton, N2 (or/and) CF2
= Prepare CF2 while reading it with a mercury manometer. Keep the total pressure slightly lower than atmospheric pressure, -100 to -150mm
The tests were carried out within the Hg range. The container was heated from the outside with an infrared lamp and the temperature inside the container was maintained at 55 to 60° C. to prevent condensation of S03 and sultone.

After the tank was sufficiently stirred, electric discharge was performed using an impulse generator (Nodel-5595, manufactured by Tohoku Metal Industry Co., Ltd.). The presence or absence of an explosion was determined by the movement of the movable plate at the top of the tank and the swing of the mercury manometer. Note that the energy applied between the two electrodes was 2.25 to 12.2 Joules.

An experiment was conducted by changing the gas composition charged into the tank as shown in Table 1 below, and the presence or absence of an explosion when electric discharge was investigated was investigated.
The results are summarized in Table 1 below.

Table 1 As is clear from the experimental results in Table 1 above, even in a system where nitrogen gas or C2F4 gas does not exist in the gas phase of the reaction system (i.e., a reaction system without dilution), the proportion of S03 (volume ratio ) is kept below 0.16, no explosion will occur. Also, the dilution ratio (volume ratio) by dilution gas is 0.
．． If it is less than 6, for example 0.3, 0.16+0
．． If the ratio of S03 is kept below 087 XO,3=0.18, explosion can be avoided.

Example I A stainless steel bubble column with an inner diameter of 2811 mm and a height of 2 Il, equipped with a C2F4 gas inlet, an S03 liquid inlet, a perforated plate, and a jacket, was charged with 900 g of sulton.

While maintaining the jacket cooling water temperature at 25°C, C2F4 gas was supplied at 28 liters/hour from the gas inlet installed at the bottom of the bubble column, and from the liquid inlet slightly above the perforated plate at the bottom of the bubble column. 8 SO3 from which inhibitors have been removed by distillation in advance
It was fed at 5g/hour. When the product flowing out from the overflow pipe provided 20c+a below the top of the column was analyzed by gas chromatography, it was found that the remaining S03 in the obtained sultone effluent was almost O. Since a large amount of sultone remained in the reaction system, the abundance ratio of S03 was kept very low, and there was no danger of explosion.

Example 2 A stainless steel autoclave with an internal volume of 84 mm and equipped with a jacket and a stirrer was charged with 70 kg of sultone and 5 kg of SO3 from which the inhibitor had been removed by distillation. The inside of the autoclave was sufficiently purged with nitrogen gas in advance to make sure there was no moisture.

After adjusting the jacket cooling water temperature to maintain the autoclave internal temperature at 25°C, gradually open the C2F4 introduction valve and inject C2F until the pressure reaches 0.3 kg/cydG.
4 was supplied into the autoclave.

The reaction started immediately, and since the pressure decreased by the amount of C2F4 consumed, C2F4 was continuously charged in an amount corresponding to the amount of C2F4 consumed. Further, the jacket cooling water temperature was adjusted so that the reactor internal temperature was maintained at 25 to 30°C.

The reaction continues in this state until there is no pressure decrease, and the supply of C2F4 is stopped at 1.5 cycles after the start of the reaction, and then 1.5 cycles after the start of the reaction.
Stirring was continued for 114 f. The total supply of C2F4 is E
l,! It weighed 3 kg.

Oh!・Cool the internal temperature of the crepe to 10℃ or less to remove unreacted C.
After purging 2F4, 11.0 kg of the product was extracted from the extraction valve at the bottom of the autoclave.

5 kg of S03 was charged again, and the reaction was repeated according to the same procedure as above.

Due to the large amount of sultone present in the reaction system, the presence of S03 was kept very low and there was no risk of explosion.

[Effects of the Invention] As described above, the present invention provides a method for producing sultone by the reaction of CF2=CF2 and S03, in which the dilution ratio is adjusted regardless of whether the dilution ratio with the diluent gas is small or when there is no dilution. Accordingly, by keeping the abundance ratio of SO3 in the reaction system below a specific value and allowing the reaction to occur, it is an excellent method that achieves the effect of effectively preventing explosions. Further, the present invention has an extremely large advantage in industrial implementation because it effectively avoids explosions and enables safe and reliable operation even in a continuous manufacturing process.

Claims (1)

[Claims] 1. CF_2 = Barfluoro-1,2 of the formula ▲There are mathematical formulas, chemical formulas, tables, etc.▼ due to the reaction of CF_2 and SO_3
- A method for producing ethane sultone, which comprises carrying out the above reaction with or without dilution with at least one kind of diluent gas selected from the group consisting of tetrafluoroethylene and an inert gas, and the reaction system is controlled by the diluent gas. The dilution ratio Z of the gas phase part is less than 0.6, and the proportion X of SO_3 in the gas phase part of the reaction system is Y
Barfluoro-1 characterized in that the reaction between CF_2=CF_2 and SO_3 is carried out by holding the following conditions:
, 2-ethane sultone manufacturing method. However, Z = diluent gas / SO_3 + sultone + diluent gas [volume ratio] X = SO_3 / SO_3 + sultone + diluent gas [volume ratio] Y = 0.16 + 0.067 Introducing CF_2=CF_2 and SO_3 into the system,
The method for producing perfluoro-1,2-ethane sultone according to claim 1, wherein CF_2=CF_2 and SO_3 are reacted.