A gas-phase NMR kinetic technique has been used for the first time to obtain accurate measurements of rate constants of some bimolecular, second-order cycloaddition reactions. As a test of the potential use of this technique for the study of second-order reactions, the rate constants and the activation parameters for the cyclodimerization reactions of chlorotrifluoroethylene (CTFE) and tetrafluoroethylene (TFE) were determined in the temperature range 240-340 degrees C, using a commercial high-temperature NMR probe. Obtaining excellent agreement of the results with published data, the technique was then applied to the reaction of 1,1-difluoroallene with 1,3-butadiene, the results of which indicate that the use of gas-phase NMR for reaction kinetics is particularly valuable when a reagent is available only in small amounts and in cases where there are several competing processes occurring simultaneously. The major processes observed in this reaction are regioselective [2+2] and [2+4] cycloadditions, whose rates and activation parameters were determined [k2 = 9.3 x 10(6) exp(-20.1 kcal x mol(-1)/RT) L/mol(-1) x s(-1) and k3 = 1.2 x 10(6) exp(-18.4 kcal x mol(-1)/RT) L/mol(-1) x s(-)(1), respectively] in the temperature range 130-210 degrees C.

New linear perfluoropolyalkylethers (PFPEs) with regularly sequenced repeat units are prepared by a four‐step synthesis starting from simple glycols and tetrafluoroethylene. The synthesis includes: (i) the reaction of glycols with tetrafluoroethylene to give bis(tetrafluoroethyl)alkyl ethers, (ii) the dehydrofluorination of the adduct with butyllithium to obtain bis(trifluorovinyl)alkyl ethers, (iii) the polymerisation of the trifluorovinyl ethers with glycols in the presence of base to make polyfluoroalkyl polyethers, and (iv) finally the fluorination of the polymers to provide PFPEs. The repeat units of the final PFPEs are altered by the variation of diols used in steps 1 and 3. Copyright © 2010 John Wiley & Sons, Ltd.