CN1267391C - Method for preparing alpha, omega diiodo perfluo-alkane - Google Patents
Method for preparing alpha, omega diiodo perfluo-alkane Download PDFInfo
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- CN1267391C CN1267391C CN 200510013228 CN200510013228A CN1267391C CN 1267391 C CN1267391 C CN 1267391C CN 200510013228 CN200510013228 CN 200510013228 CN 200510013228 A CN200510013228 A CN 200510013228A CN 1267391 C CN1267391 C CN 1267391C
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Abstract
The present invention discloses a preparation method of alpha, omega-diiodoperfluoroalkane. The method comprises the following steps: catalysts which contain copper powder or alloy powder thereof, 1, 2-diiodoperfluoroethane solvent and solid iodine are added to a closed container, C2F4 gas is led in during sufficient stir, and the reaction lasts for 40 to 60 minutes at the temperature of 140 to 200 DEG C and under the pressure of 0.6 to 1.2MPa; reaction products are heated to continue the reaction; the temperature of the materials is lowered to 140 to 200 DEG C, and the C2F4 gas is continuously led in to react with the iodine in the object system until the iodine is completely converted into 1, 2-diiodoperfluoroethane. The present invention has the advantages that the degree of telomerization and deiodination poly reaction is reasonably adjusted, the tendency of imbalance between the conversion rate and the selectivity of pure deiodination poly reaction or telomerization is overcome, the conversion rate and the selectivity of the reaction are reasonably balanced, and therefore, the conversion rate of raw materials of the reaction and the selectivity of a target product reach 75%, the total yield of the process reaches 57%, and the cost of product preparation is low.
Description
Technical Field
The invention relates to a preparation method of α omega-diiodoperfluoroalkane, in particular to a method for preparing α omega-diiodoperfluoroalkane with medium chain length by telomerization and deiodination polymerization of 1, 2-diiodoperfluoroethane, ethylene and iodine in the presence of a catalyst.
Background
The α, omega-diiodoperfluoroalkanes of medium chain length are very versatile chemical intermediates, and can be used to synthesize a variety of useful fluorochemical compounds and monomers for the production of a variety of fluoropolymers.
For example, α, the acylation compound obtained by the reaction of omega-diiodoperfluoroalkane and oleum is hydrolyzed to obtain perfluoro aliphatic diacid.
Perfluoroaliphatic diacids can be used as monomers for the synthesis of fluorine-containing polyesters, for example, α, omega-diiodoperfluoroalkane, is reacted with ethylene to form two alkylene groups at the end of the formula after the intermediate product is HI-removed,
CH2＝CH(C2F4)nCH＝CH2can be used as a monomer for synthesizing fluorine-containing polyolefin and can be further prepared into other useful fluorine-containing compounds.
Because α, omega-diiodoperfluoroalkanes have wide applications in chemical production, there are continuous reports on methods and improvements for preparing α, omega-diiodoperfluoroalkanes, and comprehensive reports on methods and improvements for preparing α, omega-diiodoperfluoroalkanes with medium chain length can be summarized into two categories:
1. the α, omega-diiodoperfluoroalkane with medium chain length is produced by taking 1, 2-diiodoperfluoroethane as a telogen and tetrafluoroethylene as a main chain substance through telomerization.
2. 1, 2-diiodoperfluoroethane is taken as a raw material, and is heated for deiodination polymerization reaction to produce α, omega-diiodoperfluoroalkane with medium chain length:
1, 2-diiodoperfluoroethane is prepared by reacting iodine with tetrafluoroethylene.
Haszoldine first proposed in 1951 a process for the preparation of α, omega-diiodoperfluoroalkanes from iodine and tetrafluoroethylene, or 1, 2-diiodoperfluoroethane and tetrafluoroethylene, by telomerization.
In 1961 Knunnyants et al tried to repeat the work of Haszeldine but the yield of the desired telomeric product was very low, and many researchers have conducted systematic studies on the reaction conditions for the preparation of α, omega-diiodoperfluoroalkane by telomerization, including temperature, pressure, reaction time, manner and rate of stirring, ratio of telogen to backbone, etc. the results show that high reaction temperatures (>260 ℃) and maintenance of high reaction pressures (>3.1MPa) are required to achieve reasonable conversions and yields in the preparation of α, omega-diiodoperfluoroalkanes from tetrafluoroethylene and iodine, or from tetrafluoroethylene and 1, 2-diiodoperfluoroethane.
Preparation of α, omega-diiodoperfluoroalkanes by telomerization of tetrafluoroethylene with 1, 2-diiodoperfluoroethane in Dindi Hasan and Hagedorn J (EP1422211) 2004The hydrocarbon is reacted at 245 deg.c and 3.65-3.86MPa for 12-20 hr in 1, 2-diiodoperfluoroethane/ethylene mol ratio of 1/1.5 to obtain reaction conversion rate of 1, 2-diiodoperfluoroethane of 96.0% to α omega-diiodoperfluoroalkane I (C)2F4)nThe selectivity of I (n ═ 2-5) was 53.0%, and the overall yield of the process was 50.1%.
In the preparation of α, omega-diiodoperfluoroalkane with medium chain length by heating 1, 2-diiodoperfluoroethane for deiodination polymerization, iodine is generated, iodine can be recovered from the reaction mixture by filtration or reduction treatment, but the operation complexity and iodine loss are increased.in 1976, JP51-133206 adopts a method of introducing tetrafluoroethylene into the iodine-containing reaction mixture obtained by heating deiodination polymerization to convert free iodine into 1, 2-diiodoperfluoroethane, and after α, omega-diiodoperfluoroalkane is recovered by distillation, 1, 2-diiodoperfluoroethane can be returned to the reactor for recycling.
In the preparation of α, omega-diiodoperfluoroalkanes of medium chain length by heating deiodination polymerization of 1, 2-diiodoperfluoroethane, perfluorocyclobutane is one of the major by-products affecting the process yield.1978 JP53-144507 proposes that the amount of perfluorocyclobutane produced can be reduced by adding free iodine to the starting material 1, 2-diiodoperfluoroethane in advance.A document JP53-144507 uses 1, 2-diiodoperfluoroethane for deiodination polymerization at 250 ℃ with the conversion of 1, 2-diiodoperfluoroethane being 70.0% for the reaction of I (C)2F4)nThe selectivity of I (n ═ 2, 3, 4) was 56.7%, 13.8%, 1.06%, respectively, the total selectivity was 71.6%, and the overall process yield was 50.1%.
In contrast to telomerization, where the conversion of 1, 2-diiodoperfluoroethane is significantly lower than that of telomerization, but the selectivity of the reaction is significantly improved, the overall yields of the two preparation methods are almost the same.
Disclosure of Invention
The invention aims to provide α, omega-diiodoperfluoroalkane I (C) with medium chain length2F4)nThe preparation method of I (n-2, 3, 4 or 5) has mild reaction conditions, high conversion rate of raw materials and high selectivity to target products, and the target products have concentrated molecular weight distribution.
The invention is realized by the following technical scheme that α omega-diiodoperfluoroalkane I (C)2F4)nA process for the preparation of I (n ═ 2, 3, 4 or 5), characterized by comprising the following steps:
1. adding 5-500 mesh Cu, Sn, Re, Ru, Rh, Pt, V or Ag metal powder or their alloy powder, or their mixture catalyst, and 1, 2-diiodoperfluoroethane IC as solvent into a sealed container2F4I and solid iodine, introducing C under full stirring2F4Reacting the gas; the reaction temperature is 140-200 ℃, the reaction pressure is 0.6-1.2MPa in the process, and the reaction time is controlled to be 40-60 minutes. The addition amount of the iodine is 0.1-3 times of the mass of the solvent 1, 2-diiodoperfluoroethane, the addition amount of the catalyst is 0.1-10% of the mass of the iodine, and C is2F4The amount of gas introduced is 2-3 times the molar amount of iodine.
2. Heating the reaction product obtained in the step 1 to 180-260 ℃, increasing the reaction pressure to 1.0-2.0MPa along with the temperature, and continuing to react for 3-5 hours.
3. After the reaction in the step 2 is finished, the temperature of the material is reduced to 140-2F4The gas reacts with the iodine in the neutralization system until the iodine is completely converted into 1, 2-diiodoperfluoroethane, and the corresponding reaction pressure is 0.6-1.2 MPa.
The catalyst is copper metal powder or copper alloy powder.
Compared with the existing α, omega-diiodo perfluoroalkane preparation process, the main advantages of the invention are as follows:
1.α, omega-diiodoperfluoroalkane is prepared by the technical scheme, telomerization reaction of tetrafluoroethylene and 1, 2-diiodoperfluoroethane and deiodination polymerization reaction of 1, 2-diiodoperfluoroethane exist in the process, wherein the 1, 2-diiodoperfluoroethane comprises 1, 2-diiodoperfluoroethane which is added into a system in advance as a solvent and 1, 2-diiodoperfluoroethane generated by reaction of tetrafluoroethylene and iodine, and proper feeding proportion is selected, so that the occurrence degree of telomerization reaction and deiodination polymerization reaction can be reasonably adjusted, the advantages and the disadvantages of the two types of reactions are complemented, the tendency that the pure deiodination polymerization reaction or telomerization reaction is excessively biased between the conversion rate of raw materials and the selectivity of target products and is unfavorable to the other side is overcome, the conversion rate of the raw materials and the selectivity of the target products of the reaction are reasonably balanced, and further measures are adopted to improve the conversion rate of the raw materials and the selectivity of the target products to a higher level.
2. The α, omega-diiodo perfluoroalkane is prepared by the technical scheme, the generation of a byproduct perfluorocyclobutane in the deiodination polymerization reaction can be reduced by adding iodine at the beginning of the reaction, and the raw materials for generating 1, 2-diiodo perfluoroethane and α, omega-diiodo perfluoroalkane with ethylene in the telomerization reaction are also used, and the addition of the iodine has double effects.
3. The addition of the proper catalyst is the key of the technical scheme, on the basis of the advantages 1 and 2, the reaction condition for preparing α omega-diiodoperfluoroalkane by the technical scheme is milder, compared with the preparation process without the catalyst, the conversion rate of raw materials and the selectivity of target products can reach 75% in a shorter reaction time at a lower reaction temperature and a lower reaction pressure, and the total yield of the process reaches 57%, which is higher than the total yield of the process ofdeiodination polymerization or telomerization in the literature by 50%.
4. Among the numerous metal catalysts that can be used in the present reaction, such as copper, tin, rhenium, ruthenium, rhodium, platinum, vanadium, silver, etc., copper is most preferably selected because it not only has good catalytic activity, but also is readily available at a low cost.
Detailed Description
Example 1:
a closed autoclave having a volume of 5 liters was charged with 3900gIC2F4I, 60g of copper powder, heating the material in the reactor to 220 ℃ while stirring after vacuumizing, raising the pressure in the reactor to 0.6MPa, and continuously reacting for 4 hours at the temperature under full stirring. After the reaction, the temperature of the materials in the kettle is quickly reduced to 160 ℃, and C is continuously and stably introduced into the reaction kettle under the condition of full stirring2F4Gas, C2F4The gas is introduced at a rate that ensures that the temperature of the reaction kettle is maintained at 160 ℃ relatively stably, and the gas C is stopped when the pressure in the kettle begins to rise2F4In the process of introducing C2F4The amount of gas was 534 g. The reaction vessel was cooled to room temperature and the pressure was released, leaving 4253g of liquid product in the vessel, which was analyzed by liquid chromatography to give a product composition of 2C: 4C: 6C: 8C: 72.83: 24.78: 2.24: 0.15 (mol%).
The results of the experiment are shown in table 1:
| composition of the mixture | Reaction raw materials (g) | Reaction product | ||
| Mol fraction | Weight fraction of | Weight (g) | ||
| I(C2F4)I | 3900 | 0.7283 | 0.6718 | 2857 |
| I(C2F4)2I | 0.2478 | 0.2932 | 1247 | |
| I(C2F4)3I | 0.0224 | 0.0324 | 138 | |
| I(C2F4)4I | 0.0015 | 0.0026 | 11 | |
| Total of | 1.00 | 1.00 | 4253 | |
According to I (C)2F4) The total process yield calculated by I is 57.26%
Comparative example 1:
a closed autoclave having a volume of 5 liters was charged with 3900gIC2F4I, after vacuumizing, heating the materials in the reactor to 250 ℃ while stirring, and increasing the pressure in the reactor to 0.8 MPa. Thereafter, the procedure is as in example 1, in the course of which C is introduced2F4The amount of gas was 527g, giving 4241g of liquid producthaving a composition, by liquid chromatography analysis, of 76.81: 4C: 6C: 8C: 19.60: 3.18: 0.41 (mol%).
The results of the experiment are shown in table 2:
| composition of the mixture | Reaction raw materials (g) | Reaction product | ||
| Mol fraction | Weight fraction of | Weight (g) | ||
| I(C2F4)I | 3900 | 0.7681 | 0.7133 | 3025 |
| I(C2F4)2I | 0.1960 | 0.2334 | 990 | |
| I(C2F4)3I | 0.0318 | 0.0462 | 196 | |
| I(C2F4)4I | 0.0041 | 0.0071 | 30 | |
| Total of | 1.00 | 1.00 | 4253 | |
According to I (C)2F4) The overall process yield calculated for I was 50.88%.
Example 2:
the process includes three stages.
1. A closed autoclave having a volume of 5 liters was charged with 700gI (C)2F4)I，1524g of iodine and 20g of copper powder are pumped into the reactor, the materials in the reactor are heated to 160 ℃ while stirring after being vacuumized, and C is continuously and stably introduced into the reactor while fully stirring2F4Gas, C2F4The gas is introduced at a rate such that the temperature and pressure of the reaction vessel are maintained at 160 deg.C and 0.7MPa, and the gas C is stopped when the pressure in the reaction vessel begins to rise2F4In stage 1, C is introduced2F4The amount of gas was 602 g.
2. The contents of the autoclave were heated to 220 ℃ with sufficient stirring, the pressure in the autoclave was 1.6MPa at this temperature, and the reaction was carried out at this temperature and pressure for 4 hours.
3. After the reaction, the temperature of the materials in the kettle is quickly reduced to 160 ℃, and C is continuously and stably introduced into the reaction kettle under full stirring as in the stage 12F4Introducing C until the pressure does not decrease any more2F4The amount of gas was 384 g. Cooling the reaction kettle to room temperature, removing pressure to obtain 3080g liquid product, and analyzing by liquid chromatography to obtain product with composition of 2C: 4C: 6C: 8C: 72.82: 24.78: 2.25: 0.15
The results of the experiment are shown in table 3:
| composition of the mixture | Reaction raw materials (g) | Reaction product | ||
| Mol fraction | Weight fraction of | Weight (g) | ||
| Free iodine | 1524 | |||
| I(C2F4)I | 700 | 0.7282 | 0.6717 | 2069 |
| I(C2F4)2I | 0.2478 | 0.2932 | 903 | |
| I(C2F4)3I | 0.0225 | 0.0325 | 100 | |
| I(C2F4)4I | 0.0015 | 0.0026 | 8 | |
| Total of | 1.00 | 1.00 | 3080 |
According to I (C)2F4) The overall process yield calculated for I was 57.27%.
Comparative example 2
The method is the same as that of example 2 except for the following differences:
in stage 1, the charge introduced into the autoclave does not comprise copper powder, C being introduced in this stage2F4The amount of gas was 604 g.
In stage 2, the temperature of the kettle is 260 ℃ and the pressure is 2.0 MPa.
In stage 3, C is introduced2F4The gas amount was 379 g.
3071g of liquid product is obtained after the reaction, and the composition of the product is 76.76: 19.61: 3.18: 0.42 according to the liquid chromatography analysis
The results of the experiment are shown in table 4:
| composition of the mixture | Reaction raw materials (g) | Reaction product | ||
| Mol fraction | Weight fraction of | Weight (g) | ||
| Free iodine | 1524 | |||
| I(C2F4)I | 700 | 0.7676 | 0.7131 | 2190 |
| I(C2F4)2I | 0.1961 | 0.2335 | 717 | |
| I(C2F4)3I | 0.0318 | 0.0462 | 142 | |
| I(C2F4)4I | 0.0042 | 0.0072 | 22 | |
| Total of | 1.00 | 1.00 | 3071 | |
According to I (C)2F4) The overall process yield calculated for I was 50.92%.
Example 3:
the process includes three stages.
1. A closed autoclave having a volume of 5 l was charged with 1600gI (C)2F4) I, 1000g of iodine and 20g of copper powder, vacuumizing, heating the materials in the reactor to 160 ℃ while stirring, and continuously and stably introducing C into the reaction kettle while fully stirring2F4Gas, C2F4The gas is introduced at a rate such that the temperature and pressure of the reaction vessel are maintained at 160 deg.C and 0.7MPa, and the gas C is stopped when the pressure in the reaction vessel begins to rise2F4In stage 1, C is introduced2F4The amount of gas was 464 g.
2. The contents of the autoclave were heated to 260 ℃ with sufficient stirring, the pressure in the autoclave was 2.0MPa at this temperature, and the reaction was carried out at this temperature and pressure for 3 hours.
3. After the reaction, the temperature of the materials in the kettle is quickly reduced to 160 ℃, and then C is continuously and stably introduced into the reaction kettle under full stirring as in the stage 12F4The gas is not reduced until the pressure is not reduced, and C is introduced in the process2F4The amount of gas was 402 g. Cooling the reaction kettle to room temperature, removing pressure, and obtaining 3120g liquid product with the composition of 2C: 4C: 6C: 8C ═ 65.89: 30.46: 3.07: 0.67 by liquid chromatography
The results of the experiment are shown in table 5:
| composition of the mixture | Reaction raw materials (g) | Reaction product | ||
| Mol fraction | Weight fraction of | Weight (g) | ||
| Free iodine | 1000 | |||
| I(C2F4)I | 1600 | 0.6589 | 0.5945 | 1855 |
| I(C2F4)2I | 0.3046 | 0.3525 | 1100 | |
| I(C2F4)3I | 0.0307 | 0.0420 | 130 | |
| I(C2F4)4I | 0.0067 | 0.0112 | 35 | |
| Total of | 1.0000 | 1.0000 | 3120 | |
According to I (C)2F4) The overall process yield calculated for I is 68.15%.
Claims (2)
1. A process for preparing α, omega-diiodoperfluoroalkanes of the formula,
I(C2F4)nwherein n is 2, 3, 4 or 5;
the method is characterized by comprising the following steps:
1) adding a catalyst of metal powder of copper, tin, rhenium, ruthenium, rhodium, platinum, vanadium, or silver or alloy powder thereof, or a mixture of the metal powder or the alloy powder thereof, having a particle size of 5 to 500 mesh, and a solvent of 1, 2-diiodoperfluoroethane IC in a closed container2F4I and solid iodine, introducing C under full stirring2F4Reacting the gas; the reaction temperature is 140-200 ℃, the reaction pressure is 0.6-1.2MPa in the process, the reaction time is controlled to be 40-60 minutes, the addition of the iodine is 0.1-3 times of the mass of the solvent 1, 2-diiodoperfluoroethane, the addition of the catalyst is 0.1-10% of the mass of the iodine, and C is2F4The introduction amount of the gas is 2 to 3 times of the molar amount of the iodine;
2) heating the reaction product obtained in the step 1) to 180-260 ℃, increasing the reaction pressure to 1.0-2.0MPa along with the temperature, and continuing to react for 3-5 hours;
3) after the reaction in the step 2) is finished, the temperature of the material is reduced to 140-2F4The gas reacts with the iodine in the neutralization system until the iodine is completely converted into 1, 2-diiodoperfluoroethane, and the corresponding reaction pressure is 0.6-1.2 MPa.
2. The process of claim 1 wherein the catalyst is copper metal powder or copper alloy powder.
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