JP3128967B2 - Method for producing 1-bromo-2-iodotetrafluoroethane - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing 1-bromo-2-iodotetrafluoroethane. More specifically,
1-bromo-2- with tetrafluoroethylene as raw material
The present invention relates to a method for producing iodotetrafluoroethane.

[0002]

2. Description of the Related Art 1-Bromo-2-iodotetrafluoroethane is useful as an intermediate for synthesizing various fluorine-containing compounds. For example, 1-bromo-2-iodotetrafluoroethane is oxidized and pyrolyzed to convert it to difluorobromoacetyl fluoride, then reacted with hexafluoropropene oxide, and further neutralized and thermally decomposed. It can be converted to perfluoro (2-bromoethyl vinyl ether), which is useful as a raw material for fluororesins. In addition, 1-bromo-2-iodotetrafluoroethane is also useful as a crosslinkable monomer for various fluoropolymers.

[0003] Conventionally, 1-bromo-2-iodotetrafluoroethane is generally produced by adding iodine bromide to tetrafluoroethylene.
However, this method not only requires the use of expensive iodine bromide, but also has the disadvantage that the reaction requires a long time of about 30 hours.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to prepare 1-bromo-2-iodotetrafluoroethane using tetrafluoroethylene as a raw material without using expensive iodine bromide, and relatively. An object of the present invention is to provide a production method capable of performing a reaction in a short time.

[0005]

SUMMARY OF THE INVENTION The object of the present invention is as follows.
This is achieved by reacting tetrafluoroethylene with bromine and iodine in the presence of a solvent to produce 1-bromo-2-iodotetrafluoroethane. This reaction is preferably performed in the presence of a chlorofluorocarbon-based solvent or fluorine oil.

As the chlorofluorocarbon-based solvent, 1-bromo-2-iodotetrafluoroethane which is a target of this reaction, and 1,2-dibromotetrafluoroethane and 1,2-diiodotetrafluoroethane which are by-products are used. Can be used. In addition, Freon-111 (1,1,1,2,2-pentachlorofluoroethane), Freon-112 (1,1,2,2-tetrachlorodifluoroethane), Freon-112a (1,1,2 Chlorine-substituted perfluoroethanes such as 1,2-tetrachlorodifluoroethane), Freon-113 (1,1,2-trichlorotrifluoroethane) and Freon-113a (1,1,1-trichlorotrifluoroethane) -
n-pentane, perfluoro-n-hexane, perfluoro-
n-octane, perfluoro (3,3-dimethylcyclohexane), perfluoroalkane such as perfluoro (1-methyldecalin), perfluoro (4-methylmorpholine), perfluoro (2-ethyltetrahydrofuran), perfluoro ( 2-butyltetrahydrofuran), perfluoro (dibutylether), perfluoro (dihexylether),
N- or O-inert solvents such as perfluoro (tripropylamine) and perfluoro (tributylamine) are used.

[0007] The fluorine oil has a viscosity of 100 cst.
The following general formula Rf, Rf ′: perfluoro lower alkyl group a, b, c: 0 to 10
An integer of 0 is used, and a commercially available product having the following structure is actually used.

[0008] These fluorocarbon solvents or fluorine oils are generally used in a weight of about the total amount of bromine and iodine.
It is used in an amount of about 0.5 to 5 times. Bromine and iodine are used in a molar ratio of iodine to bromine of about 0.5 to 2, preferably about 0.8 to 1.2.

In practice, iodine is charged into an autoclave, the pressure is reduced by a vacuum pump, and then bromine and a chlorofluorocarbon-based solvent are added, followed by stirring at about 50 to 80 ° C. for about 2 to 4 hours. This is considered to generate iodine bromide in the reaction system.

Next, the temperature of the reaction system is raised to about 70 to 90 ° C., tetrafluoroethylene is added over about 4 to 6 hours, and the mixture is stirred for about 2 to 4 hours after completion of the addition. 1-bromo-2-iodotetrafluoroethane, which is an addition reaction product, can be obtained.

When 1,2-diiodotetrafluoroethane is used as the chlorofluorocarbon-based solvent, the reaction mechanism is different from that in the case of using another chlorofluorocarbon-based solvent. It is believed that both halogen addition reactions occur. That is, under the condition of about 50 to 80 ° C. in the presence of 1,2-diiodotetrafluoroethane,
Iodine bromide is produced from bromine and iodine.
It is considered that the halogen exchange reaction occurs under the condition of time. That is, a part of iodine of 1,2-diiodotetrafluoroethane and bromine of iodine bromide perform a halogen exchange reaction, and it is considered that 1-bromo-2-iodotetrafluoroethane and iodine are generated. . As a result, most of the iodine bromide is consumed, and iodine is present in the reaction system.

Next, the reaction temperature is lowered to about 70 to 90 ° C.
Tetrafluoroethylene is added over 2 to 4 hours, and 1,2-diiodotetrafluoroethane is obtained from iodine and tetrafluoroethylene over about 2 to 4 hours after the addition. The 1,2-diiodotetrafluoroethane obtained here is almost equal to the amount of 1,2-diiodotetrafluoroethane consumed by halogen exchange in the previous reaction, and therefore, is offset by each other when viewed as a whole reaction system. The reaction is apparently the same as in the synthesis of 1-bromo-2-iodotetrafluoroethane.

However, in this case, it is a solvent.
By increasing the amount of 1,2-diiodotetrafluoroethane,
The yield of 1-bromo-2-iodotetrafluoroethane can be easily improved. This is mainly attributable to the improvement in apparent selectivity, but since the amount of 1,2-diiodotetrafluoroethane is essentially larger than the amount of bromine charged, it is important when halogen exchange is performed. This is because 1,2-dibromotetrafluoroethane, which is a by-product, is hardly produced.

The desired product can be easily separated from the reaction mixture by distillation.
Iodotetrafluoroethane can be obtained.

[0015]

In producing 1-bromo-2-iodotetrafluoroethane using tetrafluoroethylene as a starting material, expensive iodine bromide is produced by reacting tetrafluoroethylene with bromine and iodine in the presence of a solvent. The desired product can be obtained in a relatively short reaction time without using any.

[0016]

Next, the present invention will be described with reference to examples.

Example 1 In a 500 ml autoclave equipped with a stirrer, 127 g of iodine was charged, and the pressure was reduced by a vacuum pump.
g and 1,1,2-trichlorotrifluoroethane Cl ₂ FCCF ₂ C
l140 g was added, and the mixture was heated to 50 ° C. and stirred for 2 hours. Thereafter, the temperature was raised to 80 ° C., and 110 g of tetrafluoroethylene was added over 5 hours. After the completion of the dispensing, stirring was continued for another 2 hours, and then the autoclave was cooled.

The removed reaction mixture weighed 406.2 g,
When this was analyzed by ¹⁹ F-NMR, the target product, 1-bromo-
It contained 40.7% by weight of 2-iodotetrafluoroethane, and the yield based on the total amount of iodine and bromine as the charged raw materials was 53.8% by mol.

Example 2 In Example 1, the reaction solvent was changed to 1,2-dibromotetrafluoroethane BrF ₂ CCF ₂ Br.

Example 3 In Example 1, the reaction solvent was changed to 1,2-diiodotetrafluoroethane IF ₂ CCF ₂ I.

Example 4 In Example 1, the reaction solvent was Cl ₂ FCCF ₂ Cl-BrF ₂ CCF ₂ Br
(Weight ratio: 74.2: 25.8) It was changed to a mixed solvent.

Example 5 In Example 1, the reaction solvent was C ₃ F ₇ O [CF (CF ₃ ) CF ₂ O] nC ₂ F
_The reaction was performed with the change to ₅ (25 cst). After the reaction was completed, the opened autoclave was heated to 150 ° C. with stirring, and the generated gas was collected in a cooling trap at −20 ° C.

In the above Examples 2 to 5, the following results were obtained. Real-2 real-3 real-4 real-5 reaction mixture (g) 433.0 430.8 437.5 236.2 Desired product content (%) 40.8 38.9 41.0 66.1 Desired product yield (%) 57.5 54.6 58.4 50.8

Example 6 63.5 g of iodine was charged into a 500 ml autoclave equipped with a stirrer, and the pressure was reduced by a vacuum pump.
0 g and 1,2-diiodotetrafluoroethane IF ₂ CCF ₂ I 3
54 g was added, heated to 50 ° C., and stirred for 2 hours. Then 13
The temperature was raised to 0 ° C., and the mixture was stirred for 4.5 hours, then heated to 80 ° C., and 60 g of tetrafluoroethylene was added over 2.5 hours. After the completion of the dispensing, stirring was continued for another 2 hours, and then the autoclave was cooled.

The removed reaction mixture weighed 493.5 g,
When this was analyzed by ¹⁹ F-NMR, the target product, 1-bromo-
It contained 22.2% by weight of 2-iodotetrafluoroethane, and the yield based on the total amount of iodine and bromine as the charged raw materials was 71.2 mol%. aside from that,
2.5% by weight of 1,2-dibromotetrafluoroethane and 75.3% by weight of 1,2-diiodotetrafluoroethane were contained in the reaction mixture.

Example 7 In Example 6, an autoclave having a capacity of 1 L was used.
The amount of 1,2-diiodotetrafluoroethane was changed to 708 g. The removed reaction mixture is 840.4 g, in which
1-Bromo-2-iodotetrafluoroethane was contained at 14.3% by weight, and the yield was 78.0 mol%. In addition, 1,2-
0.6% by weight of dibromotetrafluoroethane and 85.1% by weight of 1,2-diiodotetrafluoroethane were contained in the reaction mixture.

Comparative Example 207 g of iodine bromide was charged into an autoclave having a capacity of 500 ml and equipped with a stirrer.
The mixture was heated to 0 ° C and 110 g of tetrafluoroethylene was added thereto over 22 hours while stirring. After the end of the dispensing, stirring was continued for further 8 hours, and then the autoclave was cooled.

The removed reaction mixture weighed 291.7 g,
The content of the target compound was 58.7% by weight, and the yield based on iodine bromide as the raw material was 55.8 mol%.

Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) C07C 17/04 C07C 19/08-19/16 CA (STN) CAOLD (STN) REGISTRY (STN)

Claims (4)

(57) [Claims] 1. A process for producing 1-bromo-2-iodotetrafluoroethane, comprising reacting tetrafluoroethylene with bromine and iodine in the presence of a solvent. 2. The method for producing 1-bromo-2-iodotetrafluoroethane according to claim 1, wherein the reaction is carried out in the presence of a chlorofluorocarbon solvent. 3. The method for producing 1-bromo-2-iodotetrafluoroethane according to claim 1, wherein the reaction is carried out in the presence of a fluorine oil. 4. A process for producing 1-bromo-2-iodotetrafluoroethane, comprising reacting bromine and iodine in the presence of a chlorofluorocarbon solvent or fluorine oil and then reacting with tetrafluoroethylene.