The present invention provides a process for preparing a diester compound of the following general formula (1), having a dimethylcyclobutane ring, wherein R.sup.1 and R.sup.2 represent, independently of each other, a monovalent hydrocarbon group having 1 to 10 carbon atoms, the process comprising reacting a dimethylcyclobutanone compound of the following general formula (2), wherein R.sup.1 is as defined above, with a phosphonic ester compound of the following general formula (3), wherein R.sup.2 and R.sup.3 represent, independently of each other, a monovalent hydrocarbon group having 1 to 10 carbon atoms, to produce the diester compound (1), having a dimethylcyclobutane ring. ##STR00001##

The present invention provides a process for preparing a diester compound of the following general formula (1), having a dimethylcyclobutane ring, wherein R.sup.1 and R.sup.2 represent, independently of each other, a monovalent hydrocarbon group having 1 to 10 carbon atoms, the process comprising reacting a dimethylcyclobutanone compound of the following general formula (2), wherein R.sup.1 is as defined above, with a phosphonic ester compound of the following general formula (3), wherein R.sup.2 and R.sup.3 represent, independently of each other, a monovalent hydrocarbon group having 1 to 10 carbon atoms, to produce the diester compound (1), having a dimethylcyclobutane ring.

##STR00001##

The present invention provides a process for preparing a diester compound of the following general formula (1), having a dimethylcyclobutane ring, wherein R.sup.1 and R.sup.2 represent, independently of each other, a monovalent hydrocarbon group having 1 to 10 carbon atoms, the process comprising reacting a dimethylcyclobutanone compound of the following general formula (2), wherein R.sup.1 is as defined above, with a phosphonic ester compound of the following general formula (3), wherein R.sup.2 and R.sup.3 represent, independently of each other, a monovalent hydrocarbon group having 1 to 10 carbon atoms, to produce the diester compound (1), having a dimethylcyclobutane ring.

##STR00001##

Provided is a process for making 2-chloro-1,1,1,2-tetrafluoropropane. The process has the step of hydrofluorinating 2-chloro-3,3,3-trifluoropropene in the presence of a catalyst selected from the group consisting of SbCl.sub.3, SbCl.sub.5, SbF.sub.5, TiCl.sub.4, SnCl.sub.4, Cr.sub.2O.sub.3, and fluorinated Cr.sub.2O.sub.3.

Provided is a process for making 2-chloro-1,1,1,2-tetrafluoropropane. The process has the step of hydrofluorinating 2-chloro-3,3,3-trifluoropropene in the presence of a catalyst selected from the group consisting of SbCl.sub.3, SbCl.sub.5, SbF.sub.5, TiCl.sub.4, SnCl.sub.4, Cr.sub.2O.sub.3, and fluorinated Cr.sub.2O.sub.3.

The present invention aims at that in a series of processes of producing 1,2,3,4-tetrachlorohexafluorobutane from 1,3-butadiene, by-products can be converted to a target substance by a relatively simple operation, raising the production efficiency as the whole process. There is provided a method for producing 1,2,3,4-tetrachloro-1,1,2,3,4,4-hexafluorobutane including step (a) of reacting chlorofluorobutane represented by the formula (1): C.sub.4Cl.sub.nF.sub.10-n (1), wherein n is an integer satisfying 5n7, with chlorine monofluoride (ClF) to thereby produce 1,2,3,4-tetrachloro-1,1,2,3,4,4-hexafluorobutane.

The present invention aims at that in a series of processes of producing 1,2,3,4-tetrachlorohexafluorobutane from 1,3-butadiene, by-products can be converted to a target substance by a relatively simple operation, raising the production efficiency as the whole process. There is provided a method for producing 1,2,3,4-tetrachloro-1,1,2,3,4,4-hexafluorobutane including step (a) of reacting chlorofluorobutane represented by the formula (1): C.sub.4Cl.sub.nF.sub.10-n (1), wherein n is an integer satisfying 5n7, with chlorine monofluoride (ClF) to thereby produce 1,2,3,4-tetrachloro-1,1,2,3,4,4-hexafluorobutane.