Can I read Proton affinities of some polyfluoroalkanes in comparison to the unsubstituted alkanes. The estimation of the proton affinities of polytetrafluoroethylene and polyethylene by applying theoretical methods on EtoBox?

Proton affinities of some polyfluoroalkanes in comparison to the unsubstituted alkanes. The estimation of the proton affinities of polytetrafluoroethylene and polyethylene by applying theoretical methods by André H. Otto; Dietrich Prescher; Erard Gey; Sigurd Schrader is a Chemistry article available to read on EtoBox.

What is Proton affinities of some polyfluoroalkanes in comparison to the unsubstituted alkanes. The estimation of the proton affinities of polytetrafluoroethylene and polyethylene by applying theoretical methods about?

Applying ab initio and semiempirical quantum chemical methods, the proton affinities (PA) for some simple polytetrafluoroethylene (PTFZ) models, and also for propane as a polyethylene (PE) model, have been estimated. Using AMI, a systematic (more than 20-30 kcal mol-') overestimation of the proton affinities was found. In contrast, a much better agreement with ab initio data was obtained by using MNDO and PM3. While the former values are too high, an underestimation by PM3 was established. Reliable results are obtained, however, when the mean values from MNDO and PM3 for PAS are used. Further investigations were carried out, applying MNDO and PM3 to larger perfluorinated alkanes and all three semiempirical methods to alkanes. Using the mean PAS from MNDO and PM3, convergence values of 116 kcal mol-' were obtained for PTFJX and 154 kcal mol-' for PE. According to the theoretical results, protonation of alkanes leads to a C-H bond cleavage in agreement with experiment. Ab initio MPn/6-31G\*//3-21G (n=2,3) geometries of protonated propane, where all bonds are kept after protonation, correspond to a transition state. The calculated PA of approximately 135 kcal mol-' falls between the r

Who reads Proton affinities of some polyfluoroalkanes in comparison to the unsubstituted alkanes. The estimation of the proton affinities of polytetrafluoroethylene and polyethylene by applying theoretical methods?

Author

André H. Otto; Dietrich Prescher; Erard Gey; Sigurd Schrader

Publisher

Elsevier Science; Elsevier ; Elsevier BV (ISSN 0022-1139)

Published

1997

Language

EN

Field

Chemistry (Physical Sciences)