Some Geometric and Electronic Structural Effects of Perfluorinating Propionyl Chloride

Abstract

Propionyl chloride and perfluoropropionyl chloride have been characterized using chirped pulse Fourier transform microwave spectroscopy between the frequency range of 8 and 14 GHz. Molecules were studied in separate experiments in supersonic expansions of argon. The (35)Cl, (37)Cl, and each of the monoisotopic (13)C substituted isotopologues of propionyl chloride were observed. The (35)Cl and (37)Cl isotopologues of perfluoropropionyl chloride were observed. Analyses of the resulting microwave spectra have yielded spectroscopic constants for the target molecules. The analyses indicate that, under the conditions of these experiments, both molecules are only detectable as cis conformers in which angleCCCO = 0 degrees . Comparisons are made between the electronic and geometric structure of propionyl chloride and perfluoropropionyl chloride, and also other acyl chlorides. The data produced are relevant in regards to quantifying the known destabilizing effect of perfluoroalky chains on carbonyl groups. Distinct differences in electronegativity between the CH(3)CH(2)CO- and CF(3)CF(2)CO- groups are discussed. Methyl group internal rotation is observed for propionyl chloride and has been analyzed to produce a V(3) barrier height.

Methyl group internal rotation and the choice of Hamiltonian for the rotational spectrum of 1,1-difluoroacetone

“…This instrument has been described in detail elsewhere [1,22] and is based upon the chirped pulse experiment previously introduced by Pate and coworkers [23][24][25]. Briefly, the instrument mixes a microwave pulse of frequency m with a fast (4 ls) linear frequency sweep of 0-1 GHz generating a m ± 1 GHz broadband pulse.…”

“…Spectroscopic examinations of partially fluorinated compounds, when taken as part of a series, allow for geometric and electronic structural differences between fully fluorinated and non-fluorinated organic frameworks to be tracked as functions of the number of fluorines present in the system, see for example Refs. [1,2].…”

The microwave spectrum of methyl chlorodifluoroacetate: Methyl internal rotation and chlorine nuclear electric quadrupole coupling

“…This instrument has been described in detail elsewhere [11,12] and is based upon the chirp pulse experiment previously introduced by Pate and coworkers. [13][14][15] Briefly, the instrument mixes a microwave pulse of frequency m with a fast (4 ls) linear frequency sweep of DC-1 GHz generating a m ± 1 GHz broadband pulse.…”

Chlorine nuclear quadrupole coupling in chlorodifluoroacetyl chloride: Theory and experiment

“…Macroscopic molecular polarization was achieved and after removal of the chirped microwave pulse the ensuing molecular free induction decay was detected, amplified, digitized and fast Fourier transformed on an oscilloscope using a 20 ls gate and a Hanning filtering window. The spectrometer has been described more fully elsewhere [19,20], see also Ref. [21].…”