JP2013166723A - Method of producing 2,2-difluorobutane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of producing 2,2-difluorobutane from only butynes and hydrogen fluoride with a high yield.SOLUTION: In a process of producing 2,2-difluorobutane by bringing butynes into contact with hydrogen fluoride, 2,2-difluorobutane can be produced at a high yield while suppressing polymerization among alkynes by controlling the number of rotations of the main shaft of a stirring blade.

Description

  The present invention relates to a method for producing 2,2-difluorobutane useful as a gas for plasma reaction such as etching or CVD, or a fluorine-containing pharmaceutical intermediate or hydrofluorocarbon solvent, which is useful in the field of manufacturing semiconductor devices. Highly purified 2,2-difluorobutane is particularly suitable for plasma etching gas, chemical vapor deposition (CVD) gas, and the like in the field of manufacturing semiconductor devices using plasma reaction.

Several methods for producing 2,2-difluorobutane have been disclosed.
In Patent Document 1, as a method of producing 2,2-difluorobutane with high efficiency and good economic efficiency, by reacting 2-butyne with hydrogen fluoride, by adding terpenes, mercaptans or phenols, 2,2-difluorobutane is obtained in a relatively good yield.
In Patent Document 2, in order to improve the yield, 2-butyne and hydrogen fluoride are reacted in a nonpolar solvent such as n-pentane to obtain 2,2-difluorobutane at a yield of 89%. ing.
Patent Document 3 discloses a method for producing 2,2-difluorobutane by bringing 2-chloro-2-butene and hydrogen fluoride into contact with each other. However, the yield is only 67%, and the industrial production level is low. Absent.
In Non-Patent Document 1, 1-butyne is used as a raw material, and the target product is obtained with a yield of 46% by contacting with 10 equivalents of hydrogen fluoride.

Japanese Patent Laid-Open No. 5-221892 Japanese Patent Application Laid-Open No. 6-1000047 US2, 364, 818

Journal of American Chemical Society, Vol. 64, 2289 (1942)

In Patent Document 1, gem-difluoroalkanes containing 2,2-difluorobutane can be produced in high yield by adding additives such as cyclic terpenes and mercaptans. Additives are not uniformly dispersed in hydrogen fluoride and alkynes, and local concentration deviation may induce polymerization of alkynes, resulting in a decrease in yield. . Further, when using mercaptans, decomposition products such as sulfur may be mixed even if distillation is performed, and there is a problem in terms of quality when used for semiconductor materials.
In Patent Document 2, when hydrogen fluoride and butynes are reacted, they are reacted in a nonpolar hydrocarbon addition system such as n-pentane or cyclopentane to produce gem-difluoroalkanes in a high yield. However, it is necessary to separate nonpolar hydrocarbons from gem-difluoroalkanes in a purification step after the reaction. In particular, in the case of 2,2-difluorobutane and n-pentane used as a solvent, the difference in boiling point between them is only about 3 to 4 ° C., and a rectifying column requiring a high number of theoretical plates is required. Cause problems in terms of equipment.
In Patent Document 3, 2-chloro-2-butene is used as a raw material. To produce this substance, a by-product of 2,2-dichlorobutane obtained by reacting 2-butanone and phosphorus pentachloride, The number of steps is increased, such as adding a step of preparing raw materials, such as hydrolysis of 2,3-dichlorobutane obtained by chlorinating 2-butene with an alkali, which is disadvantageous in terms of cost.
Non-Patent Document 1 employs a method in which 1-butyne having a terminal triple bond is previously charged into a reactor and a large excess of hydrogen fluoride is dropped, but the yield is very low.

Under such a conventional technique, no liquid additive is used, and a non-polar solvent is not used. Hydrolysis with an alkali is not required, and a liquid phase is obtained from only butynes and hydrogen fluoride obtained by refining a petroleum fraction. As a result of investigating a method for producing 2,2-difluorobutane in a high yield in the reaction, the temperature in the reactor is controlled in the range of −30 ° C. to −10 ° C., and the rotation speed of the main shaft of the stirring blade is set. The inventors have found that the desired 2,2-difluorobutane can be produced with good yield by controlling the stirring within a specific range, and the present invention has been completed.
That is, the present inventors have found that the yield of 2,2-difluorobutane produced varies greatly depending on the rotational speed of the main shaft of the stirring blade of the reactor. In other words, by optimizing the rotation speed of the main shaft of the stirring blade, undesired reactions such as polymerization reaction due to local reaction heat generation due to contact between butines are suppressed, and butynes come into contact with hydrogen fluoride efficiently. Therefore, it is estimated that the yield of 2,2-difluorobutane is improved. This tendency was particularly prominent during synthesis on an industrial production scale.

  Examples of the raw material butynes used in the present invention include hydrocarbons having a carbon-carbon triple bond in the molecule or at the molecular end, 1-butyne and 2-butyne. Among these, 2-butyne having a boiling point of 27 ° C. is preferably used because of easy handling.

In the present invention, a metal reactor such as stainless steel or hastelloy equipped with a safety valve and a stirring blade is cooled by a refrigerant, and then a predetermined amount of hydrogen fluoride is supplied and stored in the reactor.
Although the inside of the reactor is stirred by a stirring blade, since this reaction is an exothermic reaction, heat removal is required, so the reactor is maintained in the range of -30 to -10 ° C by cooling.
While maintaining the cooling temperature, the reaction is carried out in such a manner that the butynes as the raw material are fed into the reactor over time.

  The reactor is cooled to about −40 ° C. or less in a refrigerant bath such as dry ice / methanol or in an apparatus such as a circulating refrigerator. Next, a predetermined amount of hydrogen fluoride is supplied from a cylinder and stored in a reactor cooled to a predetermined temperature. The amount of hydrogen fluoride is appropriately used in the range of usually 2 to 10 mol, preferably 2 to 5 mol, with respect to 1 mol of butynes as a raw material. If the amount of hydrogen fluoride used is small, the conversion of butynes will not increase, the yield of 2,2-difluorobutane will be low, and if the amount of hydrogen fluoride is too large, polymerization will be induced easily, This causes problems such as the need for a large amount of alkali in the alkali neutralization treatment.

The contents are stirred by a stirring blade, and in that state, butynes as raw materials are a mass flow controller or the like in the case of a gaseous compound such as 1-butyne, and a pump or the like in the case of a liquid compound such as 2-butyne. Thus, a predetermined amount is fed into the reactor continuously or intermittently. The feed rate of butines is usually 600 to 3000 mol / m ³ / h, more preferably 1200 to 2400 mol / m ³ / h per unit volume and unit time of the reactor. If the supply rate is too high, the reaction with hydrogen fluoride occurs abruptly, causing rapid polymerization and causing sudden boiling of the contents, which is dangerous. In addition, if the supply rate is too slow, the reaction time becomes long, and a long time is required until the reaction is completed.

  Since this reaction is an exothermic reaction, it is usually allowed to proceed under low temperature conditions in order to suppress polymerization of butynes due to exotherm. The reaction temperature is usually in the range of −30 ° C. to −10 ° C., more preferably in the range of −30 ° C. to −10 ° C. The reaction time varies depending on the kind of raw material butynes, the amount used, the reaction temperature and the like, but is usually 0.5 hours to 10 hours, preferably 1 to 5 hours.

In this reaction, the yield of 2,2-difluorobutane, which is the target product, varies greatly depending on the rotational speed of the main shaft of the stirring blade.
If the rotational speed of the main shaft of the stirring blade is less than 13 s ⁻¹ , the mixed state of butynes and hydrogen fluoride becomes non-uniform, and the contact opportunity between butines increases, thereby causing a polymerization reaction due to heat generation. , 2-Difluorobutane yield is reduced. On the other hand, when the rotation speed of the main shaft of the stirring blade exceeds 25 s ⁻¹ , a part of the reaction mixture is scattered from the liquid phase to the gas phase, resulting in insufficient contact between butynes and hydrogen fluoride. It is estimated that the rate goes down.
As the stirring blade, an anchor type, a paddle type, or a max blend blade can be preferably used.

Therefore, in this reaction in which 2,2-difluorobutane is produced by adding hydrogen fluoride to butynes as a raw material, the rotational speed of the main shaft of the stirring blade is in the range of 13 to 25 s ⁻¹ , and about 15 to A range of 20 s ⁻¹ is preferred.

In order to complete the reaction after the supply of the raw materials is completed, a method of raising the reactor to room temperature and continuing stirring for about 1 to 2 hours is employed. In this case, the rotation speed of the main shaft of the stirring blade may be 13 to 25 s ⁻¹ described above.

  After completion of the reaction, the contents in the reactor are sent into another container containing an aqueous alkali solution such as sodium hydroxide or potassium hydroxide to neutralize unreacted hydrogen fluoride. After the two-layer separation, the upper 2,2-difluorobutane can be purified with a drying agent such as molecular sieves or alumina, and then purified by simple distillation or a distillation column with a low theoretical plate number.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited the range by the following Examples.

The analysis conditions adopted below are as follows.
・ Gas chromatography analysis (GC analysis)
Apparatus: GC-2010 (manufactured by Shimadzu Corporation)
Column: TC-1 manufactured by GL Sciences Inc., length 60 m, inner diameter 0.25 mm, film thickness 1.0 μm
Column temperature: After holding at 50 ° C. for 10 minutes, the temperature is raised at 20 ° C./minute, and then held at 250 ° C. for 10 minutes.
Injection temperature: 200 ° C
Carrier gas: Nitrogen gas split ratio: 100/1
Detector: FID

[Example 1]
The inside of a 1 L stainless steel autoclave provided with a safety valve and an anchor type stirring blade was depressurized by a vacuum pump. The autoclave was immersed in a dry ice / ethanol bath and cooled to -40 ° C. Anhydrous hydrogen fluoride (280 g) collected in advance in another small container was sent into the autoclave and stored.
The autoclave was heated to −30 ° C., and 2-butyne (340 g, manufactured by Tokyo Chemical Industry Co., Ltd.) was pumped into the autoclave at a rate of 2 mL / min over 3 hours and dropped. Meanwhile, the stirring blade was stirred with a three-one motor (manufactured by HEIDON, product name “BLh3000”; electronic control type) at a rotational speed of 13 s ⁻¹ of the main shaft of the stirring blade. After the addition of 2-butyne was completed, the autoclave was heated to room temperature, and stirring was continued for 1 hour at the same number of rotations. The contents were sampled and analyzed by gas chromatography. As a result, 2-butyne as a raw material was almost consumed.
Next, an aqueous potassium hydroxide solution in which potassium hydroxide (290 g) was dissolved in 1 L of water was charged into a 3 L glass three-necked flask and cooled to 0 ° C. The contents in the autoclave were fed into this alkaline aqueous solution while being pressurized with nitrogen to neutralize unreacted hydrogen fluoride. After standing, the upper organic layer was separated and dried with Molecular Sieves 3A. After filtering the molecular sieves 3A, the filtrate was subjected to simple distillation to obtain 539 g (yield 91%) of 2,2-difluorobutane which was the target product.

[Example 2]
In Example 1, the reaction was performed according to Example 1 except that the rotation speed of the main shaft of the stirring blade was changed from 13 s ⁻¹ to 17 s ⁻¹ . The contents in the autoclave were fed into an aqueous potassium hydroxide solution while being pressurized with nitrogen to neutralize unreacted hydrogen fluoride. After standing, the upper organic layer was separated and dried with Molecular Sieves 3A. After filtering the molecular sieves 3A, the filtrate was subjected to simple distillation to obtain 544 g (yield 92%) of 2,2-difluorobutane which was the target product.

[Example 3]
In Example 1, the reaction was performed according to Example 1 except that the number of revolutions of the main shaft of the stirring blade was changed from 13 s ⁻¹ to 25 s ⁻¹ . The contents in the autoclave were fed into an aqueous potassium hydroxide solution while being pressurized with nitrogen to neutralize unreacted hydrogen fluoride. After standing, the upper organic layer was separated and dried with Molecular Sieves 3A. After filtering the molecular sieves 3A, the filtrate was subjected to simple distillation to obtain 527 g (yield 89%) of 2,2-difluorobutane as a target product.

[Example 4]
In Example 1, 2-butyne was changed to 340 parts of 1-butyne (manufactured by Tokyo Chemical Industry Co., Ltd.), and the mass flow controller was used except that it was supplied over about 3.9 hours at a rate of 600 ml / min. The reaction was carried out in the same manner as in Example 1.
After completion of the reaction, the same operation as in Example 1 was performed to obtain 521 g of 2,2-difluorobutane which was the target product (yield 88%).

[Comparative Example 1]
In Example 1, the reaction was performed according to Example 1 except that the number of revolutions of the main shaft of the stirring blade was changed from 13 s ⁻¹ to 9 s ⁻¹ . The contents in the autoclave were fed into an aqueous potassium hydroxide solution while being pressurized with nitrogen to neutralize unreacted hydrogen fluoride. After standing, precipitation of a white solid was observed at the interface between the upper layer and the lower layer. The produced solid content and the upper organic layer were separated from the lower layer together and dried with Molecular Sieves 3A. After filtering the molecular sieves 3A and the white solid, the filtrate was subjected to simple distillation. As a result, only 420 g (yield 68%) of 2,2-difluorobutane was obtained. Moreover, when the inside of the kettle after distillation was observed, oligomeric substances were also confirmed. Thus, when the number of revolutions of the stirring blade is small, the contact efficiency between butyne-2 and hydrogen fluoride is insufficient. Rather, there is an increased chance of contact between butyne-2, so that a part of butyne-2 is polymerized. I understand that

[Comparative Example 2]
In Example 1, the reaction was performed according to Example 1 except that the number of revolutions of the main shaft of the stirring blade was changed from 13 s ⁻¹ to 33 s ⁻¹ . After the supply of butyne-2 as a raw material was completed, the contents were sampled and analyzed by gas chromatography. As a result, butin-2 remained 17% in area%, and the reaction was not completed.

  In this way, when the butynes are brought into contact with hydrogen fluoride, the reaction is carried out by controlling the rotation speed of the main shaft of the stirring blade within the optimum range, whereby terpenes as described in the prior art are used. Therefore, 2,2-difluorobutane can be obtained in a high yield and the production process can be simplified.

Claims (2)

In a liquid phase reaction in which butynes and hydrogen fluoride are brought into contact to produce 2,2-difluorobutane, the temperature in the reactor is controlled to −30 ° C. to −10 ° C., and the rotation speed of the main shaft of the stirring blade Is controlled within the range of 13 to 25 s ⁻¹ to carry out the reaction, a method for producing 2,2-difluorobutane. The method according to claim 1, wherein the butynes are 2-butyne.