The process for preparing hexafluoroisobutylene is disclosed which comprises reacting, in the liquid phase, formaldehyde or a formaldehyde-generating compound with hexafluorothioacetone dimer in an aprotic solvent containing at least a catalytic amount of an alkali metal fluoride or a sulfonic acid having general formula RSO3 H is disclosed. The preferred aprotic solvents are dimethylformamide, N-methyl pyrrolidone and dimethyl sulfoxide. The preferred alkali metal fluoride is KF; the preferred sulfonic acids are CH3 SO3 H and p-CH3 C6 H4 SO3 H. The production of hexafluoroisobutylene by contacting hexafluoropropene with elemental sulfur and a catalytic amount of an alkali metal fluoride such as KF in an aprotic solvent such as dimethyl sulfoxide or N-methyl pyrrolidone at a temperature of between about 40° and about 70° C. for a time sufficient to produce hexafluorothioacetone dimer combined with contacting said dimer in said aprotic solvent containing said alkali metal fluoride at a temperature between about 100° C. and 150° C. for a time sufficient to produce an effluent stream containing hexafluoroisobutylene which is recovered therefrom is also disclosed.
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(2008/06/13)
Conversion of hexafluorothioacetone dimer into hexafluoroacetone
The production of hexafluoroacetone by contacting, in the liquid phase, hexafluorothioacetone dimer with at least a stoichiometric amount of an aprotic solvent selected from the group consisting of dimethylacetamide, dimethylformamide, dimethyl sulfoxide and N-methyl pyrrolidone and at least a catalytic amount of an alkali metal fluoride or a sulfonic acid having general formula RSO3 H is disclosed. Dimethylformamide and dimethyl sulfoxide are the preferred aprotic solvents; KF is the preferred alkali metal fluoride; and CH3 SO3 H and pCH3 C6 H4 SO3 H are the preferred sulfonic acids. The production of hexafluoroacetone by contacting hexafluoropropene with elemental sulfur and a catalytic amount of an alkali metal fluoride in an aprotic solvent at a temperature of between about 40° and about 70° C. for a time sufficient to produce hexafluorothioacetone dimer combined with increasing the temperature to between about 90° and 150° C. and maintaining said temperature for a time sufficient to produce hexafluoroacetone is also disclosed.
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(2008/06/13)
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