The rate constants for the reactions of OH radicals with CH 3 OCF 2 CF 3 , CH 3 OCF 2 CF 2 CF 3 , and CH 3 OCF(CF 3 ) 2 have been measured over the temperature range 250-430 K. Kinetic measurements have been carried out using the flash photolysis, laser photolysis, and discharge flow methods combined respectively with the laser induced fluorescence technique. The influence of impurities in the samples was investigated by using gas-chromatography. The following Arrhenius expressions were determined: ϩ0.90 k(CH OCF CF ) ϭ (1.90 ) ϫ 3 2 3 Ϫ0.61 exp[Ϫ(1510 Ϯ 120)/T], exp[Ϫ(1540 Ϯ 80)/T], and 3 3 2

The OH reaction rate constants have been measured for CH3OCF2CHF2, CHF2OCH2CF2CHF2, CHF2OCH2CF2CF3, and CF3CH2OCF2CHF2 over the temperature range 250−430 K. Kinetic measurements have been carried out using the flash photolysis, laser photolysis, and discharge flow methods, combined respectively with the laser-induced fluorescence technique to monitor the OH radical concentrations. The influence of impurities contained in the samples of fluorinated ethers has been investigated by means of sample purification using gas chromatography. No sizable effect of impurities was found on the measured rate constants of these fluorinated ethers, if the purified samples were used in the kinetic measurements. The Arrhenius rate constants have been determined from the respective kinetic data as k(CH3OCF2CHF2) = 2.60 × 10-12 exp[−(1420 ± 170)/T], k(CHF2OCH2CF2CHF2) = 2.49 × 10-12 exp[−(1500 ± 170)/T], k(CHF2OCH2CF2CF3) = 2.14 × 10-12 exp[−(1580 ± 170)/T], and k(CF3CH2OCF2CHF2) = 1.49 × 10-12 exp[−(1520 ± 170)/T] cm3 molecule-1 s-1, where the quoted errors represent the 95% confidence level and included systematic errors. Uncertainty factors at 298 K (with the formulation of the NASA panel for data evaluation14) for these fluorinated ethers were 1.1.

A Pb/Al bimetal system was used to carry out reductive addition of tetrachloromethane, tetrabromomethane, bromotrichloromethane, trichloroacetamide, and trichloroacetonitrile to aldehydes. Subsequent 1,2-elimination of the halogen atom and hydroxyl group from the coupling products was also performed with the Pb/Al bimetal system. The technology was successfully applied to stereocontrolled syntheses of ethyl trans-and c¿s-3-(2,2dihaloethenyl)-2,2-dimethylcyclopropanecarboxylates.

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