JP2511689B2 - Bromine-containing iodine compound and its synthetic intermediate - Google Patents

Description

TECHNICAL FIELD The present invention relates to a bromine-containing iodine compound and a synthetic intermediate thereof. More specifically, it relates to a bromine-containing iodine compound and a synthetic intermediate thereof that form a radical that becomes an addition growth reaction point during the production of a fluorinated copolymer and a cross-linking point during the vulcanization of the fluorinated copolymer. .

[Conventional technology]

Generally, a fluorinated elastomer vulcanizate is excellent in heat resistance, solvent resistance, weather resistance, ozone resistance, creep resistance, etc., and therefore, for example, oil seals, packings, gaskets, sealing materials such as O-rings, diaphragms, Widely used industrially as hose linings, coating agents, adhesives, etc.

Conventionally, as one method for obtaining such a fluorinated elastomer vulcanizate, a peroxide vulcanization method using an organic peroxide as a vulcanizing agent has been adopted, and as the fluorinated elastomer in this case, iodine or Those in which bromine is bonded as a crosslinking point are used. Some examples of them are described below, but they all have the following problems.

JP-A-53-125491: Method using an iodine compound represented by the general formula RfIx (Rf is a fluorohydrocarbon group or a chlorofluorohydrocarbon group). This iodine compound is disclosed in the following JP-A-60-221,401. As described in (1) above, it is expensive and highly toxic, and iodine bound to the fluorine-containing elastomer is easily released under the irradiation of light.

JP 60-221,409 JP: Formula RI _{1 2} (R is a hydrocarbon is a group having 1 to 3 carbon atoms) toxicity than the iodine compound method using an iodine compound represented by the inexpensive, yet the RfIx compound However, it is inferior in terms of vulcanization rate, heat resistance of the vulcanizate and compression set.

JP-A-59-20310: Method using a bromine compound represented by the general formula RBrx (R is a saturated aliphatic hydrocarbon group). This invention is jointly with the invention described in JP-A-53-125491. It is said that some of the inventors have in common and have superior performance to the fluorine-containing elastomer bonded with iodine. In fact, the fluorine-containing elastomer bonded with bromine is good in light stability, but inferior in vulcanization rate, heat resistance and compression set of the vulcanized product.

JP-B-54-1585: Bromotrifluoroethylene, 4-bromo-3,3,4,4
-Method using brominated olefin compound such as tetrafluorobutene-1 The resulting fluoroelastomer is not only easy to gel and inferior in processability (flow characteristics), but also in terms of elongation and compression set of the vulcanized product. Is not enough.

JP-A-60-195,113: General formula ROCX = CYZ (one or two of X, Y and Z is selected from bromine and iodine, the rest is hydrogen, fluorine or chlorine, and R is a chain) Or a cyclic alkyl group, an alkenyl group, or an aryl group), and the vinyl ether cure site monomer represented by about 5 mol% or less,
Preferred is a method of copolymerizing 0.1 to 1.5 mol% As the vinyl ether curing site monomer, a compound substituted with both bromine and iodine can be selected from the above general formula, but in the publication, X, Y and It is described that a bromine-containing or iodine-containing vinyl ether whose halogen substituent represented by Z is bromine or, to a lesser extent, iodine is used as a cure site monomer.

Also in the case of this method, the same drawbacks as those of the invention described in Japanese Patent Publication No. 54-1585 can be seen.

[Problems to be Solved by the Invention]

The present applicant solves the problems found in the above-mentioned prior art and produces a peroxide-vulcanizable fluorine-containing elastomer capable of providing a vulcanizate excellent in processability, vulcanization characteristics and vulcanization physical properties. As a result of repeated earnest studies on the above, by polymerizing a fluorinated olefin in the presence of a bromine-containing iodine compound as a chain transfer agent, and simultaneously introducing bromine and iodine as crosslinking points into a fluorine-containing elastomer molecule, such a problem can be solved. We first found that it could be effectively resolved (Japanese Patent Application No. 62-58145).

The bromine-containing iodine compound used here has the general formula RBrn
Im (R is a fluorohydrocarbon group, a chlorofluorohydrocarbon group, a chlorohydrocarbon group or a hydrocarbon group), n and m are both 1 or 2, and mainly n and m are both 1 is the preferred one.

The present inventor has found that 2 bromine atoms and 1 iodine atom or 1 bromine atom, 1 iodine atom and 1
A trifunctional bromine-containing iodine compound having each unsaturated bond was newly synthesized as a chain transfer agent for producing a fluoroelastomer, and at the same time, a synthetic intermediate thereof was also newly synthesized.

[Means for solving the problem]

Therefore, the present invention relates to a bromine-containing iodine compound, which comprises 3,4-dibromo-1-iodo-1,
1,2,2,4,4-hexafluorobutane or 2-bromo-
4-iodo-1,1,3,3,4,4-hexafluorobutene-1
Consists of.

The present invention also relates to 3,4-dibromo-1-iodo-1,1,2,
As an intermediate for synthesizing 2,4,4-hexafluorobutane, 4-iodo-1,1,3,3,4,4-hexafluorobutene-1 and 1,4-diiodo-1,1, Provide 3,3,4,4-hexafluorobutane.

3,4-Dibromo-1-iodo-1,1,2,2,4,4-hexafluorobutane (hereinafter abbreviated as dibromoiodohexafluorobutane) is synthesized from tetrafluoroethylene through the following steps. It

(1) CF ₂ = CF ₂ + I ₂ → ICF ₂ CF ₂ I + I (CF ₂ CF ₂ ) _2-20
I (2) ICF ₂ CF ₂ I + CF ₂ = CH ₂ → ICF ₂ CF ₂ CH ₂ CF ₂ I (3) ICF ₂ CF ₂ CH ₂ CF ₂ I + KOH → ICF ₂ CF ₂ CH = CF ₂ (4) ICF ₂ CF ₂ CH = CF ₂ + Br ₂ → ICF ₂ CF ₂ CHBrCF ₂ Br Of these series of reaction steps, the reaction (1) is described in JP-B-53.
No. 17565, the reactions (2) to (4) are novel and each give a novel substance.

In the reaction of (2), 1,2-diiodoperfluoroethane (hereinafter, abbreviated as diiodoperfluoroethane) is charged into an autoclave, and vinylidene fluoride is added thereto in an amount of about 30 to 30.
It is carried out by press-fitting under a pressure of 40 Kg / cm ² and reacting at about 100 to 200 ° C., preferably about 120 to 160 ° C. for about 50 to 120 hours. The ultimate pressure in this reaction is about 45 to 50 Kg / c.
the m ^2.

In the reaction of (3), 1,2-diiodo-1,1,3,3,4,4-hexafluorobutane (hereinafter, abbreviated as diiodohexafluorobutane) that is the reaction product of (2) is distilled. After purification with about 30-60% by weight potassium hydroxide aqueous solution and about 80-12
The reaction is carried out at 0 ° C., and a dehydroiodination reaction is carried out.

In the reaction of (4), 4-iodo-1,1,3,3,4,4-hexafluorobutene-1 (hereinafter abbreviated as iodohexafluorobutene-1) which is the reaction product of (3) is bromine-containing. And add
It is carried out by reacting at about 80 to 120 ° C. However, the conversion of this reaction is as low as about 6 to 8%, but the conversion can be improved by adding a small amount of niobium as a catalyst thereto. The final product obtained, dibromoiodohexafluorobutane, is purified by distillation.

In addition, 2-bromo-4-iodo-1,1,3,3,4,4-hexafluorobutene-1 (hereinafter abbreviated as bromoiodohexafluorobutene-1) is 1-bromo-2,2- It is synthesized from difluoroethylene through the following steps.

(1) CF ₂ = CHBr + ICl → CF ₂ ClCHBrI (2) CF ₂ ClCHBrI + KOH → CF ₂ = CBrI (3) CF ₂ CBrI + CF ₂ = CF ₂ → CF ₂ = CBrCF ₂ CF ₂ I Of these series of reaction steps, ( The reactions 1) and 2) are described in J. Org. Chem. Vol. 23, pp. 1661-5 (1958), and the reaction (3) is new and gives a new substance.

This reaction (3) is 1-synthesized by the above method.
Bromo-1-iodo-2,2-difluoroethylene (hereinafter abbreviated as bromoiododifluoroethylene) is R-11
Since it is obtained as a 3 solution, it is used for the reaction as it is and charged into an autoclave, and tetrafluoroethylene is injected therein at a pressure of about 5 to 30 Kg / cm ² , preferably about 10 to 20 Kg / cm ² , and about 100 to It is carried out by reacting at 200 ° C., preferably about 120 to 160 ° C. for about 200 to 300 hours. In the reaction mixture, unreacted raw material (bromoiododifluoroethylene), liberated I ₂ and ICF ₂ CF ₂ I added to tetrafluoroethylene are mixed, so I ₂ is removed by reduction and purified by distillation. And isolate the desired product.

[Action] and [Effect of the Invention] According to the present invention, two kinds of bromine-containing iodine compounds, namely, 3,
4-dibromo-1-iodo-1,1,2,2,4,4-hexafluorobutane and 2-bromo-4-iodo-1,1,3,3,4,4
-Hexafluorobutene-1 is also the former synthetic intermediate, 4-iodo-1,1,3,3,4,4-hexafluorobutene-1 and 1,4-diiodo-1,1,3,3 Each of 4,4,4-hexafluorobutane is provided as a new substance.

These bromine-containing iodine compounds easily cleave bromine and iodine radicals during the polymerization reaction of fluorine-containing olefins by the action of an organic peroxide radical generation source, and the radicals generated there are highly reactive, so that the monomer The reaction is stopped by adding growth reaction and then withdrawing bromine and iodine from the bromine-containing iodine compound to give a fluorine-containing elastomer having bromine and iodine bonded to the molecular ends.

Further, the fluorine-containing elastomer thus produced easily undergoes radical cleavage of bromine and iodine at the molecular end in the presence of a radical generation source, and the polymer radical generated there has the same reactivity, so that it is polymerized multiple times. It is also possible to obtain a segmented polymer depending on the type of the polymerized monomer by carrying out.

These bromine-containing iodine compounds generally give fluorine-containing elastomers which are bound to the molecular ends to achieve efficient cross-linking, and the content thereof is about 0.001 to 5% by weight as bromine and iodine in the resulting fluorine-containing elastomer, respectively.
It is preferably used in an amount of about 0.01 to 3% by weight for binding. If the amount is less than this, the crosslinking density of the fluoroelastomer will be low and vulcanization will be insufficient. On the other hand, if the amount is greater than this, the rubber elasticity (elongation) and heat resistance will be poor. It comes to come.

〔Example〕

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

Example 1 In a stainless steel autoclave having a capacity of 500 ml, 436 g of diiodoperfluoroethane was charged, and after depressurization, vinylidene fluoride was injected under its own pressure to a pressure of about 35 kg / cm ² . The autoclave was heated to 140 ° C. and reacted for 70 hours. The maximum pressure at this time was 45 Kg / cm ² . After cooling the autoclave and opening it, and taking out the contents,
Since I ₂ was precipitated, this was reduced with an aqueous sodium sulfite solution to obtain 339 g of a liquid. Gas chromatograph and mass spectrometry (Shimadzu GC-MS QP-1000
As a result, it was confirmed that diiodohexafluorobutane was produced at a conversion rate of 56.7%. Then, distillation was carried out to obtain 168.5 g of diiodohexafluorobutane having a boiling point of 48 ° C./10 mmHg (yield 32.7%).

¹³ F-NMR (CF ₃ COOH standard): +38 ppm multiplet +19 ppm singlet −30 ppm multiplet Example 2 Water-cooled condenser, capacity −80 m equipped with −80 ° C. trap, dropping funnel and stirrer connected to it, respectively
150 g of water and 90 g of potassium hydroxide were placed in a l-separable flask, and 138 g of diiodohexafluorobutane obtained in Example 1 was slowly added dropwise while heating and stirring at 100 ° C., and heating was continued for 2 hours after completion of the addition. Stirring was continued. 51.1 g of iodohexalfluorobutene-1 in the trap
(Yield 54.0%) was collected.

Gas chromatography-mass spectrometry: M / e fragment _{290 ICF 2 CF 2 CH = CF} 2 177 ICF 2 - 127 I- 113 CF 2 = CHCF 2 - 100 -CF 2 CF 2 - 63 CF 2 = CH- 19 F-NMR ( CF ₃ COOH standard): +29 +12 +4 +3 ppm Multiplet Example 3 Iodohexafluorobutene-1 obtained in Example 2
44.4 g of the above was placed in an eggplant flask with a water-cooled condenser having a capacity of 30 ml, to which 36.7 g of bromine and 3 g of niobium were added, and 1
The reaction was carried out at 00 ° C for 24 hours. After completion of the reaction, unreacted bromine was reduced and filtered by treating the reaction mixture with an aqueous sodium sulfite solution. The filter cake was analyzed by gas chromatography and the same mass spectrometry, and the conversion rate was 28.8.
It was confirmed that dibromoiodohexafluorobutane was produced in%. This is further distilled under reduced pressure (30 mmH
g), dibromoiodohexafluorobutane as a residue
7.0 g (yield 10.2%) was obtained.

¹⁹ F-NMR (CF ₃ COOH standard): +30 +20 +19 -26 ppm Both are multiplets Example 4 4889 g of R-113 solution of bromoiododifluoroethylene (concentration 56.8 wt%) was placed in an autoclave having a pre-depressurized volume of 10. After charging, tetrafluoroethylene was further injected under its own pressure up to a pressure input of about 10 kg / cm ² . After this, the temperature was raised with vigorous stirring as much as possible, and the reaction temperature was maintained at 140 ° C. The reaction pressure is increased to 25 Kg / cm ^2, was dropped over time, the autoclave was returned to room temperature at the time the pressure drops to about 15 Kg / cm ^2, tetrafluoroethylene pressed again -
The operation of increasing temperature and cooling was repeated, and the reaction was stopped when the total time of maintaining the temperature at 140 ° C. reached 240 hours. The reaction product recovered in an amount of 6426 g was subjected to gas chromatography and mass spectrometry, and it was confirmed that bromoiodohexafluorobutene-1 was produced at a conversion rate of 38.5%. Further, this was subjected to vacuum distillation to obtain 95 g (yield 2.5%) of bromoiodohexafluorobutene-1 as a fraction having a boiling point of 51 ° C./11 mmHg.

¹⁹ F-NMR (CF ₃ COOH standard): -22 to -50 ppm Multiplet infrared absorption spectrum: 1700 cm ^-1 C = C

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location C07C 21/14 C07C 21/14 21/18 21/18 C08F 2/38 MCL C08F 2/38 MCL 14/16 MKT 14/16 MKT

Claims (4)

(57) [Claims] 1. 1,4-Dibromo-1-iodo-1,1,2,2,4,4
-Hexafluorobutane. 2. 4-Iodo-1,1,3,3,4,4-hexafluorobutene-1. 3. 1,4-Diiodo-1,1,3,3,4,4-hexafluorobutane. 4. 2-Bromo-4-iodo-1,1,3,3,4,4-
Hexafluorobutene-1.