2557-72-4Relevant academic research and scientific papers
Bimolecular kinetic studies with high-temperature gas-phase 19F NMR: Cycloaddition reactions of fluoroolefins
Shtarov,Krusic,Smart,Dolbier Jr.
, p. 9956 - 9962 (2001)
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 °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=9.3×106 exp(-20.1 kcal mol-1/RT) L/mol-1 S-1 and k3=1.2×106 exp(- 18.4 kcal mol-1/RT) L/mol-1 S-1, respectively] in the temperature range 130-210 °C.
