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The hydrogen and chlorine abstraction reactions by silyl (H3Si*) and trichlorosilyl (Cl3Si*) radical from the three chloromethanes ClCH3, Cl2CH2 and Cl3CH were investigated theoretically. Findings from traditional ab initio techniques were compared with those derived from a density functional method using the hybrid B3LYP and the pure BLYP functional. Results at all computational levels showed that the chlorine abstraction is highly preferred with respect to the hydrogen abstraction as experimentally observed.

A study on the chlorine channel of the OClO fragmentation was conducted to show that three-photon laser-induced fluorescence and total vacuum ultraviolet fluorescence can be used for the 'soft' identification of the new Cl atoms. These techniques do not require secondary photolysis processes resulting from high-energy photons. This study also aimed to use the method to examine the mode-selective degradation of OClO into Cl atoms.

The reaction rate parameter uncertainties in the chlorine partitioning and ozone in upper stratospheric models was investigated. A direct sensitivity analysis was used on local altitude boxes from the LLNL-2D model. Sensitivities were utilized to propagate rate constant errors through the model and to isolate those steps that are predominant in the uncertainties in the computed concentrations. The reaction OH + ClO -> HCl + O2(1Delta) was confirmed to the key source of uncertainty in chlorine partitioning in the 2-D atmospheric model.

Absolute rate coefficient measurements were performed for the Cl atom reaction with a series of esters at room temperature and in the pressure range 15-60 Torr by applying the laser photolysis-resonance fluorescence method. The reactivity of Cl with the investigated esters can be compared with the reactivity of OH radicals with the same esters. The Cl and OH reaction rate coefficients indicated similar trends with the number of carbon atoms and the branching in the esters as was shown for Cl and OH reactions with alkanes.

A study was conducted to analyze the tile reaction by monitoring the ethyl radical product using resonance-enhanced multiphoton ionization proceeding at 242 nm through highly dissociative Rydberg states. Core-extracted ion arrival profiles were determined with the photolysis laser polarization method. The measured C2H5 spatial anisotropy was then utilized to estimate the product center-of-mass velocity and change the speed distribution tot he differential cross area.

The effects of magnesium on the partitioning of fluorine and chlorine between biotite and melt were analyzed in a natural F-rich vitrophyric rhyolite from Spro Mountain, UT. Spectroscopic analysis of the Spor Mountain rhyolite indicated the presence of glass and biotite laths with fluorite, quartz and zircon. The presence of magnesium in the sample modulated halogen partitioning due to the reequilibration of degassed magma.

Stable Cl isotope ratios, measured in marine pore waters associated with the Barbados and Nankai subduction zones, extend significantly (to [similar to] -8% per thousand) the range of [[Delta].sup.37] Cl values reported for natural waters. These relatively large negative values, together with geologic and chemical evidence from Barbados and Nankai and recent laboratory data showing that hydrous silicate minerals (i.e., those with structural OH sites) are enriched up to 7.5% per thousand in 37Cl relative to seawater, strongly suggest that the isotopic composition of Cl in pore waters from subduction zones reflects diagenetic and metamorphic dehydration and transformation reactions. These reactions involve clays and/or other hydrous silicate phases at depth in the fluid source regions. Chlorine therefore cannot be considered geochemically conservative in these systems. The uptake of Cl by hydrous phases provides a mechanism by which Cl can be cycled into the mantle through subduction zones. Thus, stable Cl isotopes should help in determining the extent to which Cl and companion excess volatiles like [H.sub.2]O and C[O.sub.2] cycle between the crust and mantle.

The determination of transient chlorine concentration profiles and chlorine insertion in biofilms consisting of Klebsiella pneumoniae and Pseudomonas aeruginosa during disinfection by using a microelectrode reveal that chlorine concentrations in biofilms are less than that in bulk liquid and that the diffusion of chlorine in the matrix of the biofilms controls chlorine insertion. The region of chlorine insertion exhibits an overlapping with the nonrespiring areas. The controlled insertion of chlorine into the biofilms may be responsible for the reduced effectiveness of chlorine against the biofilms.

2-hydroxy-3-chrolobiphenyl constitutes the axenic methanotrophic culture strain CSC1 yielded by mixed-culture aquifer samples. The sample oxidized to hydroxylated chlorobiphenyl intermediates by 2-chlorobiphyenyl indicates its constituent compounds. The axenic incubation culture extracts also exhibit hydroxylated chlorobiphenyl isomer.

9-azabicyclononanes 2 and 3 can be prepared by transannular N-heterocyclization of 1,5-cyclooctadiene which employs B-bromo- or N-iodosuccinimide and cyanamide. This method is unsuccessful when N-chlorosuccinimide was used. Dehydration of the carboxamide after nucleophilic displacement with chlorine affected the preparation of chloro-substituted derivative.

Heat and chlorine influence the survival of Hartmannella vermiformis and the successive intracellular development of Legionella pneumophila. For chlorine concentration between 2 ppm and 4 ppm, H. vermiformis trophozoites are slightly affected by chlorine. There is a decrease in the concentration of H. vermiformis at 50 degrees Celsius and chlorine concentration of 2 ppm. The two organisms do not survive at a concentration of 10.0 ppm and a temperature of 60 degrees Celsius.

Mo K-alpha X-radiation is used to refine the R indices of approximately 2% of the crystal structure of three calcil c2/m amphiboles with different chlorine contents. Two distinct sites, O3 and O3', are separated by approximately 0.5 angstroms and are split by the monovalent anion site. A strong preference for Fe2+-Cl short-range order is seen in the variations in bond lengths, as a function of cation and anion site populations. A concomitant expansion of the tetrahedral chain occurs partly by chain straightening but mostly by the increased substitution of (4)Al for Si. This is required by the expansion of the octahedral sheet caused by the incorporation of chlorine. Increasing Fe2+, K and /4~Al are required by the increasing chlorine content in the amphiboles.

The sensitivity to free chlorine of feline calicivirus (FCV), a norovirus surrogate with respect to the chlorine demand is studied. The analysis reveals that the sensitivity of FCV to free chlorine increases with a reduction in the host cell debris.

The geometry and vibrational frequencies of the GdX3 (X = F and Cl) molecules are analyzed at the ab initio level with extended basis sets, employing relativistic effective core potential, and evaluating electronic correlation by means of second-order perturbative (MP2) and coupled cluster (CCSD and CCSD(T)) methods. Anharmonicities, temperature and inert-gas matrix effects are explicitly included in the study.

Investigations of the metabolite (pm)-(1beta,6alpha,9beta, 10alpha)-9-chloro-10-hydroxy-8-(methoxycarbonyl)-4- methylene-2, 5-dioxabicyclo-(4.4.0)dec-7-en-3-one (1), accomplished the total synthesis of racemic 1 by the lactonization of diester 3, which was obtained from dimethyl chorismate. 1 is a chlorine-containing metabolite that was isolated from various fungi.

Chlorine is used in swimming pools to maintain algae growth to a minimum and to prevent the growth of bacteria. However, chlorine has been found to wear down swimsuit fabrics [...]

A study investigated the branching ratio of the reaction of OH with ClO conducted at pressures between 100 and 200 Torr and at a range of temperatures extending to those found in the lower stratosphere using a novel, laboratory-developed technique. It also conducted statistical rate theory calculations on the OH + lO reaction system. Experimental and theoretical calculations were compared. Experimental methods, findings and conclusions are discussed.

Fourier transform infrared-smog chamber methods were employed to assess the rate constants for the gas-phase reaction of Cl and F atoms with CH3C(O)C(O)CH3 and F atoms with CH3C(O)F. Two pathways for the reaction of Cl and F atoms with CH3C(O)C(O)CH3 were observed. Pulse radiolysis in combination with ultraviolet absorption spectroscopy was employed to investigate the kinetics of the reaction of F atoms with CH3C(O)C(O)CH3.