1 research outputs found
Photochemistry of UV-Excited Trifluoroacetylacetone and Hexafluoroacetylacetone I: Infrared Spectra of Fluorinated Methylfuranones Formed by HF Photoelimination
The photochemistry of gas-phase 1,1,1-trifluoroacetylacetone
(TFAA)
excited with ultraviolet (UV) light involves a significant photoelimination
channel that produces hydrogen fluoride and a fluorinated methylfuranone,
2,2-difluoro-5-methyl-3Â(2<i>H</i>)-furanone (2FMF). This
pathway is remarkable because it is a gas-phase unimolecular reaction
that forms a five-membered ring product. This report is the first
of such a TFAA photoelimination channel, which is similar to one observed
with 1,1,1,5,5,5-hexafluoroacetylacetone (HFAA), resulting in 2,2-difluoro-5-trifluoromethyl-3Â(2<i>H</i>)-furanone. We present infrared spectral observations of
2FMF produced by pulsed, UV-laser excitation of TFAA, along with analogous
results from HFAA, supported by density functional theory (DFT) computational
studies. DFT results for the infrared spectrum of 5-methyl-3Â(2<i>H</i>)-furanone, the expected comparable acetylacetone photoelimination
product, help suggest that UV excitation of acetylacetone fails to
follow a similar type of photoelimination. We use a weighted RMS approach
as a figure of merit for comparing calculated infrared frequencies
with experimental data. Results from the three acetylacetones reveal
how the presence of fluorine atoms in acetylacetone influences the
gas-phase molecular photochemistry