JPS6022690B2 - Method for producing hexafluoro-2-propanone - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing hexafluoro-2-propanone, and more particularly to a method for efficiently producing hexafluoroprobene from hexafluoro-2-propanone using a specific catalyst.

In the present invention, hexafluoroprobene refers to a straight or branched alkene in which all hydrogen atoms have been replaced by one or more halogen atoms. Here, halogen refers to fluorine, chlorine and bromine.

Perhaloalkanones are useful as intermediates for the synthesis of various halohydrocarbons, and in particular, their carbonyl groups easily add to water, alcohols, or other hydroxyl group-containing compounds to produce diols, acetals, etc. For this reason, it is widely used as an intermediate raw material.

Furthermore, hydrates of perhaloalkanones have uses as solvents and plasticizers for polymeric substances containing hydrogen-bonding groups such as polyamides and acetal resins. Conventionally, one method for producing perhaloalkanones having various uses is to oxidize perhaloalkenes to obtain epoxy perhaloalkenes, and then rearrange the epoxy perhaloalkenes to obtain perhaloalkanones. method is known.

For example, perhaloalkenes and oxygen
Perhaloalkanes can be obtained by contacting them with activated silica gel at 000°C, which can be rearranged in the presence of Lewis acids such as aluminum oxide to produce perhaloalkanones [US Pat. No. 37]
7 payment 3 account statement]. As mentioned above, the secondary method requires a two-stage reaction, but as a result of various studies, the present inventors have already found that silica alumina can be obtained by treating it with a fluorinating agent. We have found a method for producing hexafluoro-2-propanone from hexafluoroprobene and oxygen in one step by using fluorinated silica alumina as a catalyst.

That is, the gist of the present invention is to obtain hexafluoro-2-propanone by contacting fluorinated silica alumina with hexafluoroprobene in the gas phase at 80 to 300 o in the presence of oxygen. -Lists in the method of producing propanone.

The fluorinated silica aluminum used as a catalyst in the method of the present invention contains aluminum, silicon, fluorine and oxygen as essential components, and in particular has a fluorine content of 0.5 to
It is desirable to use 50% by weight.

Such fluorinated silica alumina can usually be prepared by treating silica alumina with a fluorinating agent.

The ratio of silica to alumina is preferably 25:7 by weight.
5-90:10, particularly preferably 30:70-80:2
It is 0. As the fluorinating agent, either an inorganic fluorinating agent or an organic fluorinating agent can be used.

Examples of inorganic fluorinating agents include silicon tetrafluoride, sulfur fluoride (eg, sulfur tetrafluoride, sulfur hexafluoride), sulfuryl fluoride, thionyl fluoride, and the like. Examples of organic fluorinating agents include fluorohydrocarbons, chlorofluorohydrocarbons, bromofluorohydrocarbons, and the like. In addition, aHbX in the fluorine-containing compound C (where X is an oxygen or nitrogen atom, n is an integer from 1 to 8, a is an integer from 1 to m+m, b is an integer from 0 to m+m-, m is x
When x is an oxygen atom, it represents an integer of 2, and when x is a nitrogen atom, it represents an integer of 3. ) can also be used (Samurai Kaisho 47-1
578 specification). Specific examples include hexafluoroacetone, hexafluoro-1,2-epoxyethane, decafluoroether, tri(trifluoromethyl)amine, and tetrafluorethyl methyl ether. Furthermore, when sulfur fluoride, sulfuryl fluoride, or thionyl fluoride is used as a fluorinating agent, silica alumina may be brought into contact with the sulfur fluoride at, for example, 300 to 500°C.

Although a sulfur compound may be produced as a by-product in some cases, this does not serve as a catalyst in the reaction of the method of the present invention. Moreover, when using an organic fluorinating agent as a fluorinating agent, silica alumina is used in an amount of 100 to 60 pp0.

It is preferable to contact the fluorinated hydrocarbon at 150 to 45 psi. Note that when an organic fluorinating agent is used as the fluorinating agent, silica alumina may be treated with a chlorohydrocarbon or a bromohydrocarbon prior to the treatment.

Furthermore, during the treatment of silica alumina and an organic fluorinating agent, a chlorohydrocarbon or a bromo hydrocarbon may be allowed to coexist, thereby allowing the fluorination of silica alumina to be carried out more smoothly at a lower temperature. The above-mentioned chlorohydrocarbons or bromohydrocarbons are saturated or unsaturated hydrocarbons having not more than 8 carbon atoms (preferably not more than 4), in which at least one hydrogen is replaced by a chlorine or bromine atom. is used.

In general, a high degree of substitution by chlorine or bromine atoms is preferred, and substitution may be carried out by either one or both of chlorine or bromine atoms. Among the various chloro and bromo hydrocarbons, particular preference is given to using perchlorohydrocarbons. That is, fluorinated silica alumina can be produced by using silica alumina as a raw material instead of activated alumina in the conventional method for producing fluorinated alumina.

However, production methods using hydrogen fluoride, ammonium fluoride, etc. as fluorinating agents are inappropriate. When this catalyst is used for a long time, carbonaceous deposits are formed on the surface and the catalytic activity is reduced.

In such cases, it is possible to restore the catalytic activity by heating it to 350-500 DEG C. under an atmosphere of oxygen or an oxygen-containing mixture, for example air. To carry out the process of the invention, hexafluoroproben and oxygen may be brought into contact with the above-mentioned catalyst according to conventional contacting means.

That is, a suitable reactor is used, a flow system or a closed system is adopted, and a hexafluoropolymer is added to a fixed bed, a moving bed, or a fluidized bed of the catalyst.

All you have to do is bring the pen into contact with oxygen. The mixing ratio of hexafluoroproben and oxygen is usually 1:10 to 0.1 (molar ratio), particularly preferably 1:2 to 0.3.

Outside the above range, the oxygen content may be small or the rate of change may be low.
It shows that the yield decreases when there is a lot of oxygen. If necessary, an inert gas such as carbon dioxide, nitrogen, or helium may be used as a diluent. The reaction temperature during contact is usually 80 to 30,000 qo, preferably 100 to 250 qo
It is.

When the temperature is low, the rate of change decreases, and when the temperature is high, the yield decreases. There is almost no reaction at temperatures lower than 80°C, and the yield is extremely low at temperatures higher than 300 qo.

The pressure used is atmospheric pressure or higher, and generally higher pressures are preferred because the conversion rate and yield are improved. Industrially, it is common to use a pressure of 0 to 20k9G. The contact time depends on other conditions, especially the temperature, and as with other general reactions, it is better to shorten the contact time at higher temperatures and longer at lower temperatures.

Generally, the time is preferably 30 minutes or less and 0.9 seconds or more. The longer the contact time, the higher the conversion rate. A suitable contact time is selected from an economical point of view. For example, about 100-250q○
In a flow system using a temperature of 1 to 10 minutes, it is common to use a reaction time of 1 second to 10 minutes. As mentioned above, whereas the conventional method employs a multi-step reaction to produce perhaloalkanone from perhaloalkene, the method of the present invention performs this in one step, and has this point. The latter can be said to be more efficient than the former.

Incidentally, when the reaction mixture was analyzed, epoxyhexafluoroprobene, which was observed to be produced in the middle of the former, was not detected in the latter. Further, the latter reaction in the former is generally carried out using a Lewis acid as a catalyst. Example 1 Granular silica alumina (SiQ: phantom 203
Weight ratio 60:40) 35 minutes were prepared, and 40 minutes was prepared in a N2 stream.
The temperature was raised to 0'0, heat dehydration was performed at that temperature for 2 hours, and then cooled to 200 qo.

At 20,000 yen, the gas was switched to N2, and CC12F2 gas was flowed at 50 g/min for 4 hours.

Then, the mixture was maintained in an air flow of 300 oo for 1 hour to obtain fluorinated silica alumina. As a result of cooling this fluorinated silica alumina bed and removing and analyzing about 0.5 liters of reactant, the amount of fluorine in the fluorinated silica alumina was 3.2% by weight.
Met. Next, this fluorinated silica alumina bed was
The mixture was heated to 0 qo and hexafluoroblobene and oxygen were passed through at a flow rate of 50 [/min and 30 [/min], respectively, under conditions of a total pressure of 1 atm.

After 3 hours, the exhaust gas was analyzed by gas chromatography and the conversion rate of hexafluoroprobene was 10.
0 mol%, and the yield of hexafluoro-2-propanone at that time was Satoshi. It was 8 mol%.

A comparative test was conducted using silica alumina as a catalyst under the same conditions except that the temperature was 200 qo and the aeration time was 15 hours.

Claims (1)

[Claims] 1. Hexafluoro-2-propanone, which is obtained by contacting fluorinated silica alumina with oxygen and hexafluoropropene in a gas phase at 80 to 300°C to obtain hexafluoro-2-propanone. Manufacturing method. 2. The manufacturing method according to item 1 above, wherein the fluorinated silica alumina contains 0.5 to 50% by weight of fluorine. 3. The manufacturing method according to item 1 or 2 above, wherein the fluorinated silica alumina is obtained by treating silica alumina with an inorganic fluorinating agent. 4 The inorganic fluorinating agent is silicon tetrafluoride, sulfur fluoride,
4. The production method according to item 3, wherein at least one substance selected from the group consisting of sulfuryl fluoride and thionyl fluoride is used. 5. The manufacturing method according to item 1 or 2, wherein the fluorinated silica alumina is obtained by treating silica alumina with an organic fluorinating agent. 6. The fifth above, wherein the organic fluorinating agent is a fluorinated hydrocarbon.
Manufacturing method described in section.