“A 500 cm3 round bottom three-neck flask was fitted with a thermometer, dropping funnel, still head and condenser. KOH (36 g, 0.64 mol) was added to the flask followed by water (100 cm3). With magnetic stirring and ice cooling, hexafluoro-2-propanol (Aldrich Chemical Co., 100 g, 0.59 mol) was added so that the temperature did not exceed 20°C. The mixture was then warmed to 70°C and methyl sulfate (82 g, 0.65 mol) added at such a rate to keep the temperature in the range 68—70°C. The product distilled (still head temperature 50—54°C) and was collected in an ice cooled flask to give a cloudy liquid (82 g). This product was stirred with powdered KOH (0.5 g) for 0.5 h and then distilled to give a colourless liquid (77.8 g, b.p. 49—50°C). This liquid was shaken with ice-cold potassium hydroxide solution (1 M, 50 cm3), then separated (it is the lower layer) and distilled through a 15-cm silvered vacuum jacketed column, discarding the first 0.6 g (b.p. 47.5—49°C), to give the product (68.3 g, b.p. 49—51°C).”

“Generation of gas-air mixtures

Dynamic exposure conditions were used with trifluoroethanol and hexafluoroisopropanol. Briefly, the solvents were evaporated, diluted with room air, and led to a 3.3-l exposure chamber. Each nominal concentration was calculated from the amount of evaporated chemical and the total gas-air flow (set between 18 and 25 l/min). Chamber concentrations were monitored continuously by infrared (IR) spectroscopy (Nielsen and Alarie 1982; ASTM 1984). The differences between the nominal and the monitored exposure concentrations were normally less than 10%. Air concentrations are given in ppm: ml gas per m3 gas-air mixture (Kristiansen et al. 1989). Static exposure conditions were used with investigation of methyl hexafluoroisopropyl ether due to the large quantities of the chemical required to elicit response. The ether was evaporated in a 34.6-l stainless steel tank. Tank, exposure chamber, IR analyser and a pump were connected in a closed loop system (Hansen et al. 1991; Nielsen and Alarie 1992). The exact exposure concentrations were obtained from IR spectroscopy.

Exposure conditions

Each mouse was placed in a body plethysmograph attached to the exposure chamber so that the head of the mouse protruded into the 320 exposure chamber which was fitted with four plethysmographs. The respiratory rate and the relative tidal volume of each mouse were obtained continuously by attaching a pressure transducer to each plethysmograph. Data were recorded on a dynograph and collected on a computer. At each exposure experiment, a preexposure period of 10 min was used for collecting base line values. The exposure was 30 min with the dynamic conditions and 10 min with the static conditions. Then the exposure chamber was flushed with room air for a 20-min recovery period (Nielsen and Alarie 1982; ASTM 1984; Nielsen et al. 1993).”

Note: concentrations were converted to mg/m3 by the extractor.

Male Ssc:CF-1 Mice