Production process and purification process for 1,2,3,4-tetrachlorohexafluorobutane
It is an object of the present invention to provide a process for producing 1,2,3,4 -tetrachlorohexafluorobutane industrially inexpensively and efficiently by utilizing expensive fluorine gas efficiently and to provide a process which is capable of stably producing 1,2,3,4 -tetrachlorohexafluorobutane and in which, by carrying out fluorination reaction at a low temperature, side reactions such as formation of a low-boiling substance due to cleavage of C—C bonds and formation of an excess fluoride are difficult to occur. The process for producing 1,2,3,4-tetrachlorohexafluorobutane of the present invention is characterized in that it includes feeding fluorine gas to 1,2,3,4-tetrachlorobutane using plural reactors in the presence of a solvent and in the absence of a catalyst to allow the 1,2,3,4-tetrachlorobutane and the fluorine gas to react with each other, wherein a part or all of unreacted fluorine gas discharged from one reactor is introduced into a reactor different from said one reactor.
1. A process for producing 1,2,3,4-tetrachlorohexafluorobutane, comprising feeding fluorine gas to 1,2,3,4-tetrachlorobutane using plural reactors in the presence of a solvent containing hydrogen fluoride and in the absence of a catalyst to allow the 1,2,3,4-tetrachlorobutane and the fluorine gas to react with each other, wherein
the plural reactors are comprised of a first reactor on an upstream side and a second reactor on a downstream side and are arranged in series, and a part or all of unreacted fluorine discharged from the first reactor is introduced into the second reactor,
the concentration of fluorine gas in a dilute mixed gas introduced into the first reactor is not less than 30% by volume, and
the concentration of fluorine gas contained in discharged gas from the second reactor is not more than 10% by volume.
2. The process for producing 1,2,3,4-tetrachlorohexafluorobutane as claimed in claim 1 , wherein a part or all of unreacted fluorine gas discharged from a reactor on the downstream side is further introduced into a reactor on the upstream side.
3. The process for producing 1,2,3,4-tetrachlorohexafluorobutane as claimed in claim 1 , wherein in 100% by mass of the 1,2,3,4-tetrachlorobutane, a dl form that is an optical isomer thereof is contained in an amount of not less than 40% by mass.
4. The process for producing 1,2,3,4-tetrachlorohexafluorobutane as claimed in claim 1 , wherein the reaction solution containing 1,2,3,4-tetrachlorohexafluorobutane obtained by the reaction of the 1,2,3,4-tetrachlorobutane with the fluorine gas is introduced into a distillation column,
the reaction solution is separated into a liquid containing 1,2,3,4-tetrachlorohexafluorobutane and a liquid containing the solvent, and
the separated liquid containing the solvent is returned to a reactor for carrying out reaction of 1,2,3,4-tetrachlorobutane with fluorine gas and recycled.
5. A process for purifying 1,2,3,4-tetrachlorohexafluorobutane, comprising:
introducing a reaction solution containing 1,2,3,4-tetrachlorohexafluorobutane obtained in the process as claimed in claim 1 into a distillation column,
separating the reaction solution into a liquid containing 1,2,3,4-tetrachlorohexafluorobutane and a liquid containing the solvent, and
bringing at least a part of the separated liquid containing 1,2,3,4-tetrachlorohexafluorobutane into contact with an alkaline substance and/or water.
6. The process for purifying 1,2,3,4-tetrachlorohexafluorobutane as claimed in claim 5 , wherein the liquid containing 1,2,3,4-tetrachlorohexafluorobutane which has been brought into contact with an alkaline substance and/or water is further brought into contact with a porous purifying agent.
7. The process for purifying 1,2,3,4-tetrachlorohexafluorobutane as claimed in claim 6 , wherein the porous purifying agent is zeolite.
8. The process for producing 1,2,3,4-tetrachlorohexafluorobutane as claimed in claim 2 , wherein the plural reactors are two reactors arranged in series.