OH Radical and Chlorine Atom Kinetics of Substituted Aromatic Compounds: 4-chlorobenzotrifluoride (-ClCHCF).

The mechanisms for the OH radical and Cl atom gas-phase reaction kinetics of substituted aromatic compounds remain a topic of atmospheric and combustion chemistry research. 4-Chlorobenzotrifluoride (-chlorobenzotrifluoride, -ClCHCF, PCBTF) is a commonly used substituted aromatic volatile organic compound (VOC) in solvent-based coatings. As such, PCBTF is classified as a volatile chemical product (VCP) whose release into the atmosphere potentially impacts air quality.

Kinetic fall-off behavior for the Cl + Furan-2,5-dione (CHO, maleic anhydride) reaction.

Rate coefficients, k, for the gas-phase Cl + Furan-2,5-dione (C4H2O3, maleic anhydride) reaction were measured over the 15-500 torr (He and N2 bath gas) pressure range at temperatures between 283 and 323 K. Kinetic measurements were performed using pulsed laser photolysis (PLP) to produce Cl atoms and atomic resonance fluorescence (RF) to monitor the Cl atom temporal profile. Complementary relative rate (RR) measurements were performed at 296 K and 620 torr pressure (syn.

Conformational Preference Determined by C-H···π Interaction of an O-H···O Hydrogen-Bonded Binary Complex of p-Fluorophenol with 2,5-Dihydrofuran: A Laser-Induced Fluorescence Spectroscopy Study.

Conformational preferences of a binary hydrogen-bonded complex between p-fluorophenol (pFP) and 2,5-dihydrofuran (DHF) have been studied by means of laser induced fluorescence (LIF) spectroscopy in a supersonic jet expansion. Calculation predicts two major conformers for this complex, one having a nearly linear geometry in which the two molecular moieties are bound only by an O-H···O H-bond, but in the other an additional C-H···π type interaction between an ortho C-H group of pFP and ethylene group of DHF contributes to the binding stabilization and results in a folded geometry for the complex with respect to a global view, although the H-bond angle of the latter is relatively larger. This prediction is realized experimentally by identifying transitions corresponding to the two discrete conformers in a vibrationally resolved LIF excitation spectrum of the complex, and the red shifts of S-S origin band of pFP moiety of the two conformers are 542 and 659 cm, respectively.

Photo-oxidation of Acetone to Formic Acid in Synthetic Air and Its Atmospheric Implication.

Acetone photo-oxidation in synthetic air under exposure of 311 nm ultraviolet light has been studied, and the photo-oxidation products are identified by means of infrared spectroscopy. Analysis reveals that formic acid is one of the major products, although there have been debates in the past concerning the authenticity of formation of this acid in synthetic air via the photo-oxidation pathway. The quantum yield of formation of this acid is similar to that of other major photoproducts like methanol, formaldehyde, and carbon monoxide.