Anthracene as a Launchpad for a Phosphinidene Sulfide and for Generation of a Phosphorus-Sulfur Material Having the Composition PS, a Vulcanized Red Phosphorus That Is Yellow.

Thermolysis of a pair of dibenzo-7-phosphanorbornadiene compounds is shown to lead to differing behaviors: phosphinidene sulfide release and formation of amorphous PS. These compounds, BuP(S)A (1, A = CH or anthracene; 59% isol. yield) and HP(S)A (2; 63%), are available through thionation of BuPA and the new secondary phosphine HPA (5), prepared from MeNPA and DIBAL-H in 50% yield.

Kinetics of the Reactions between the Criegee Intermediate CHOO and Alcohols.

Reactions of the simplest Criegee intermediate (CHOO) with a series of alcohols have been studied in a flash photolysis flow reactor. Laser photolysis of diiodomethane at 355 nm in the presence of molecular oxygen was used to produce CHOO, and the absolute number densities were determined as a function of delay time from analysis of broadband transient absorption spectra obtained using a pulsed LED. The kinetics for the reactions of CHOO with methanol, ethanol, and 2-propanol were measured under pseudo-first-order conditions at 295 K, yielding rate constants of (1.

UV photodissociation dynamics of CHICl and its role as a photolytic precursor for a chlorinated Criegee intermediate.

Photolysis of geminal diiodoalkanes in the presence of molecular oxygen has become an established route to the laboratory production of several Criegee intermediates, and such compounds also have marine sources. Here, we explore the role that the trihaloalkane, chlorodiiodomethane (CHICl), may play as a photolytic precursor for the chlorinated Criegee intermediate ClCHOO. CHICl has been synthesized and its UV absorption spectrum measured; relative to that of CHI the spectrum is shifted to longer wavelength and the photolysis lifetime is calculated to be less than two minutes.

Reactions between Criegee Intermediates and the Inorganic Acids HCl and HNO3 : Kinetics and Atmospheric Implications.

Criegee intermediates (CIs) are a class of reactive radicals that are thought to play a key role in atmospheric chemistry through reactions with trace species that can lead to aerosol particle formation. Recent work has suggested that water vapor is likely to be the dominant sink for some CIs, although reactions with trace species that are sufficiently rapid can be locally competitive. Herein, we use broadband transient absorption spectroscopy to measure rate constants for the reactions of the simplest CI, CH2 OO, with two inorganic acids, HCl and HNO3 , both of which are present in polluted urban atmospheres.

Dynamics and spectroscopy of CH₂OO excited electronic states.

The excited states of the Criegee intermediate CH2OO are studied in molecular dynamics simulations using directly potentials from multi-reference perturbation theory (MR-PT2). The photoexcitation of the species is simulated, and trajectories are propagated in time on the excited state. Some of the photoexcitation events lead to direct fragmentation of the molecule, but other trajectories describe at least several vibrations in the excited state, that may terminate by relaxation to the ground electronic state.

High resolution absolute absorption cross sections of the B ̃(1)A'-X ̃(1)A' transition of the CH2OO biradical.

Carbonyl oxides, or Criegee intermediates, are formed from the gas phase ozonolysis of alkenes and play a pivotal role in night-time and urban area atmospheric chemistry. Significant discrepancies exist among measurements of the strong B ̃(1)A'-X ̃(1)A' electronic transition of the simplest Criegee intermediate, CH2OO in the visible/near-UV. We report room temperature spectra of the B ̃(1)A'-X ̃(1)A' electronic absorption band of CH2OO acquired at higher resolution using both single-pass broadband absorption and cavity ring-down spectroscopy.

Kinetics of IO Production in the CH2I + O2 Reaction Studied by Cavity Ring-Down Spectroscopy.

Cavity ring-down spectroscopy was used to study the kinetics of formation of IO radicals in the reaction of CH2I + O2 in a flow cell at 52 ± 3 Torr total pressure of N2 diluent and a temperature of 295 K. CH2I was produced by photolysis of CH2I2 at 355 nm and IO probed on the A(2)Π3/2–X(2)Π3/2 (3,0) and (3,1) bands at 435.70 and 448.