Critical parameters and normal boiling temperatures of five fluorinated ethers and two fluorinated ketones

The critical parameters and normal boiling temperatures of five fluorinated ethers. (1,1,1,2,4,4,4-heptafluoroisobutyl trifluoromethyl ether, tert-per fluorobutyl methyl ether, 1,1,1,2-tetrafluoro-2-difluoromethoxyethyl difluo romethyl ether, 2,3,3,5,5,6,6-heptafluoro-1,4-dioxane, and 2-trifluoromethy l-4,4,5,5-tetrafluoro-1,3-dioxolane) and two fluorinated ketones (1,1,1,2,2 -pentafluoro-3-butanone and 1,1,1,2-tetrafluoro-2-trifluoromethyl-3-butanon e) were measured using static-type apparatuses, in which a small amount of a sample fluid of 5 cm(3) was required to determine the thermodynamic prope rties accurately. The uncertainties in the critical parameters were +/- 30 mK in temperature, +/-2 kPa in pressure, +/-0.2% in density, and +/- 10 mK in normal boiling temperature, respectively. Lydersen's group contribution method estimated the critical parameters fairly well, but no group contribu tion method could predict the normal boiling temperature reasonably.