The fluorine-initiated reaction of tetrafluoroethylene with oxygen, in a liquid phase at low temperature, leads to almost quantitative yields of polymeric perfluoroethers made by CF2CF2O and CF2O units and containing variable amounts of peroxy bonds. This chain reaction is studied in a series of semibatch experiments, and the results are interpreted on the basis of a rather simplified reaction mechanism involving a sequence of elementary steps of different free-radical species. A most unexpected experimental finding is the positive action exerted by the oxygen pressure on the initiation rate; this effect is attributed to a competitive reaction of fluorine atoms with molecular oxygen to form FO 2 reactive species which are able to produce a substantial number of chain-initiating biradicals. The kinetic relationships deduced from the overall reaction model are proved to fairly describe, in a quantitative way, the correlation between the operating variables and the various polymer structure indexes. The values of the typical kinetic parameters of the process are estimated; they appear to be consistent with an emerging general picture of the reactivity characteristics of the different perfluorinated oxygenated radical species in the condensed state.

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The chiral differentiation of the enantiomers of 2-methylbutanoic acid, 2-methylpentanoic acid and 2-methylhexanoic acid was achieved by diastereomeric derivatization with (R)-( -)-pantolactone. GC separation on achiral DB-I, DB-1701 and DB-WAX capillary columns as well as 'H-and 13C-NMR enantiodiscrimination were obtained, affording good resolution and quantitative evaluation of enantiomer composition. The method applied to 2-methylbutanoic acid present in the aromatic fraction extracted from cultivated strawberry (Fragaria uesca) indicated a high enantiomeric excess of the (S)-isomer.

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