Download or read book Kinetics and Mechanisms of the Hydroxyl Radical Initiated Oxidation of Oxygenated Volatile Organic Compounds Under Simulated Tropospheric Conditions written by Konrad Stemmler and published by . This book was released on 1998 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Kinetics and Mechanisms of the OH Radical Initiated Oxidation of Volatile Organic Compounds Under Simulated Tropospheric Conditions written by Jürg Ernst Eberhard and published by . This book was released on 1994 with total page 93 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Atmospheric Degradation of Organic Substances written by Walter Klöpffer and published by John Wiley & Sons. This book was released on 2008-01-08 with total page 258 pages. Available in PDF, EPUB and Kindle. Book excerpt: This compilation on the degradation of 1,100 commercially important chemical products is the first publication to make this knowledge publicly accessible in one book. The data and annotations have been painstakingly assembled over a 10-year period in a collaboration between academia and regulatory authorities. The work explains in detail the methods, including computational ones, for the environmental assessment of volatile and semi-volatile substances, and is rounded off with data tables of degradation rates. A key resource for manufacturers and regulators of such substances.

Download or read book Kinetic and Mechanistic Studies of the Hydroxyl Radical Initiated Photo oxidation of Saturated Hydrocarbons Under Simulated Atmospheric Conditions written by and published by . This book was released on 1988 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Kinetics and Products of the Reactions of Hydroxyl Radicals with Selected Volatile Organic Compounds Including Oxygenated Compounds written by Heidi Lynn Bethel and published by . This book was released on 2002 with total page 414 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Mechanisms of Atmospheric Oxidation of the Oxygenates written by Jack Calvert and published by Oxford University Press. This book was released on 2011-08-01 with total page 1634 pages. Available in PDF, EPUB and Kindle. Book excerpt: Prepared by an international team of eminent atmospheric scientists, Mechanisms of Atmospheric Oxidation of the Oxygenates is an authoritative source of information on the role of oxygenates in the chemistry of the atmosphere. The oxygenates, including the many different alcohols, ethers, aldehydes, ketones, acids, esters, and nitrogen-atom containing oxygenates, are of special interest today due to their increased use as alternative fuels and fuel additives. This book describes the physical properties of oxygenates, as well as the chemical and photochemical parameters that determine their reaction pathways in the atmosphere. Quantitative descriptions of the pathways of the oxygenates from release or formation in the atmosphere to final products are provided, as is a comprehensive review and evaluation of the extensive kinetic literature on the atmospheric chemistry of the different oxygenates and their many halogen-atom substituted analogues. This book will be of interest to modelers of atmospheric chemistry, environmental scientists and engineers, and air quality planning agencies as a useful input for development of realistic modules designed to simulate the atmospheric chemistry of the oxygenates, their major oxidation products, and their influence on ozone and other trace gases within the troposhere.

Download or read book Chemistry of the Upper and Lower Atmosphere written by Barbara J. Finlayson-Pitts and published by Elsevier. This book was released on 1999-11-17 with total page 993 pages. Available in PDF, EPUB and Kindle. Book excerpt: Here is the most comprehensive and up-to-date treatment of one of the hottest areas of chemical research. The treatment of fundamental kinetics and photochemistry will be highly useful to chemistry students and their instructors at the graduate level, as well as postdoctoral fellows entering this new, exciting, and well-funded field with a Ph.D. in a related discipline (e.g., analytical, organic, or physical chemistry, chemical physics, etc.). Chemistry of the Upper and Lower Atmosphere provides postgraduate researchers and teachers with a uniquely detailed, comprehensive, and authoritative resource. The text bridges the "gap" between the fundamental chemistry of the earth's atmosphere and "real world" examples of its application to the development of sound scientific risk assessments and associated risk management control strategies for both tropospheric and stratospheric pollutants. Serves as a graduate textbook and "must have" reference for all atmospheric scientists Provides more than 5000 references to the literature through the end of 1998 Presents tables of new actinic flux data for the troposphere and stratospher (0-40km) Summarizes kinetic and photochemical date for the troposphere and stratosphere Features problems at the end of most chapters to enhance the book's use in teaching Includes applications of the OZIPR box model with comprehensive chemistry for student use

Download or read book Hydroxyl Radical Reactions with Volatile Organic Compounds Under Simulated Tropospheric Conditions written by Marco Semadeni and published by . This book was released on 1994 with total page 141 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Mechanisms of Atmospheric Oxidation of the Alkanes written by Jack G Calvert and published by Oxford University Press. This book was released on 2008-09-15 with total page 1005 pages. Available in PDF, EPUB and Kindle. Book excerpt: An international team of eminent atmospheric scientists have prepared Mechanisms of Atmospheric Oxidation of the Alkanes as an authoritative source of information on the role of alkanes in the chemistry of the atmosphere. The book includes the properties of the alkanes and haloalkanes, as well as a comprehensive review and evaluation of the existing literature on the atmospheric chemistry of the alkanes and their major atmospheric oxidation products, and the various approaches now used to model the alkane atmospheric chemistry. Comprehensive coverage is given of both the unsubstituted alkanes and the many haloalkanes. All the existing quality measurements of the rate coefficients for the reactions of OH, Cl, O(3P), NO3, and O3 with the alkanes, the haloalkanes, and their major oxidation products have been reviewed and evaluated. The expert authors then give recommendations of the most reliable kinetic data. They also review the extensive literature on the mechanisms and rates and modes of photodecomposition of the haloalkanes and the products of atmospheric oxidation of the alkanes and the haloalkanes, and make recommendations for future use by atmospheric scientists. The evaluations presented allow an extrapolation of the existing kinetic and photochemical data to those alkanes and haloalkanes that are as yet unstudied. The current book should be of special interest and value to the modelers of atmospheric chemistry as a useful input for development of realistic modules designed to simulate the atmospheric chemistry of the alkanes, their major oxidation products, and their influence on ozone and other trace gases within the troposphere.

Download or read book Kinetic Study of Reactions with Interest to Atmospheric Chemistry by Simultaneous Detection of OH and RO2 Radicals Coupled to Laser Photolysis written by Emmanuel Assaf and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The hydroxyl radical OH and hydroperoxy radical HO2 radicals are key species in many oxidation processes in the atmosphere. The degradation of volatile organic compounds under tropospheric conditions is induced by reactions with hydroxyl radicals followed by the subsequent chemistry of the initial OH oxidation products with O2. This thesis was focused on the kinetic study of some of these atmospherically relevant reactions to better understand their oxidation mechanisms using an experimental system of laser photolysis coupled to Laser Induced Fluorescence (LIF, for OH radical) and continuous-wave Cavity Ring-Down Spectroscopy (cw-CRDS, for OH, HO2 and RO2 radicals) detection techniques. After determining the infrared spectrum of OH, HO2 and CH3O2 radicals in the near infrared region and the absorption cross-sections of few selected lines, four systems were studied with the above mentioned techniques: CH3O2 + OH, C2H5O2 + OH, C3H7O2 + OH and C4H9O2 + OH. The rate constant and the HO2 yield of the four reactions were determined. In addition, the rate constants of few secondary reactions such as CH3O + HO2, CH3O + CH3O or OH + HO2 have been determined.

Download or read book The Hydroxyl Radical Initiated Oxidation of Unsaturated Hydrocarbons in the Troposphere written by Erin Elizabeth Tullos and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Isoprene is the dominant non-methane organic compound emitted by vegetation into the atmosphere, with a global emission rate of ~ 500 Tg yr-1. Its oxidation serves as a major source of ground level ozone in North America during the summer months. Despite the significant impact on tropospheric chemistry, questions remain concerning the detailed oxidation mechanism. The initial step in the mechanism is the addition of OH to form four distinct isomers. The relative branching between these isomers influences the distribution of the final products. I present a comprehensive investigation into the mechanistic details of early steps in the oxidation mechanism of unsaturated hydrocarbons in the troposphere and employ theoretical and experimental techniques. To understand the detailed kinetics of the initial OH addition to unsaturated hydrocarbons, I first present a model developed for the ethylene-OH system. I present the details of a robust two-transition state model. I extend the developed two-transition state model to the case of OH addition to isoprene. Excellent agreement with observed temperature and pressure dependent rate constants affords a high confidence level in understanding of the kinetics and in the calculated branching ratio of the initial OH addition step. I then focus attention on the subsequent reactivity of the OH-isoprene adducts. Until recently, all four of the OH-isoprene adducts were supposed to have reacted with O2 via addition to form alkylperoxy radicals. Previous computational results suggest that two of the OH-isoprene adducts undergo an intramolecular cyclic isomerization followed by hydrogen abstraction by O2 to form stable carbonyl compounds. I have synthesized photolytic precursors, presenting a novel approach to probe the subsequent reactivity of individual hydroxyalkyl radicals. Initial verification of the cyclic isomerization pathway involved synthesis of the photolytic precursor corresponding to the 1,3-butadiene-OH adduct. A culmination of theoretical and experimental techniques allowed verification of the cyclic isomerization pathway. I synthesized the photolytic precursor, which provided a single isoprene-OH adduct. Employing laser photolysis/laser induced fluorescence, time-dependent multiplexed mass spectrometry, velocity map ion imaging, and theoretical techniques, we present the full characterization of the reactivity of the single isoprene-OH adduct in the presence of O2.

Download or read book The Mechanisms of Reactions Influencing Atmospheric Ozone written by Jack G. Calvert and published by Oxford University Press. This book was released on 2015-05-13 with total page 608 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ozone, an important trace component, is critical to life on Earth and to atmospheric chemistry. The presence of ozone profoundly impacts the physical structure of the atmosphere and meteorology. Ozone is also an important photolytic source for HO radicals, the driving force for most of the chemistry that occurs in the lower atmosphere, is essential to shielding biota, and is the only molecule in the atmosphere that provides protection from UV radiation in the 250-300 nm region. However, recent concerns regarding environmental issues have inspired a need for a greater understanding of ozone, and the effects that it has on the Earth's atmosphere. The Mechanisms of Reactions Influencing Atmospheric Ozone provides an overview of the chemical processes associated with the formation and loss of ozone in the atmosphere, meeting the need for a greater body of knowledge regarding atmospheric chemistry. Renowned atmospheric researcher Jack Calvert and his coauthors discuss the various chemical and physical properties of the earth's atmosphere, the ways in which ozone is formed and destroyed, and the mechanisms of various ozone chemical reactions in the different spheres of the atmosphere. The volume is rich with valuable knowledge and useful descriptions, and will appeal to environmental scientists and engineers alike. A thorough analysis of the processes related to tropospheric ozone, The Mechanisms of Reactions Influencing Atmospheric Ozone is an essential resource for those hoping to combat the continuing and future environmental problems, particularly issues that require a deeper understanding of atmospheric chemistry.

Download or read book Chemical Processes in Atmospheric Oxidation written by Georges Le Bras and published by Springer Science & Business Media. This book was released on 1997 with total page 348 pages. Available in PDF, EPUB and Kindle. Book excerpt: Oxidation and removal of atmospheric constituents involve complex sequences of reactions which can lead to the production of photo-oxidants such as ozone. In order to understand and model these complex reaction sequences, it is necessary to have a comprehensive understanding of reaction mechanisms and accurate estimates of kinetic parameters for relevant gas-phase atmospheric reactions. This book presents recent advances in the field and includes the following topics: e.g. the oxidation of simple organic compounds, NOx kinetics and mechanisms, OH radical production and rate constants for the OH attack on more complex organic compounds, peroxy and alkoxy radical reactions, photo-oxidation of aromatic and biogenic compounds, and the interaction between radical species.

Download or read book Unimolecular Reaction of Hydroxyperoxyl Radicals in the Troposphere written by Sui So and published by . This book was released on 2016 with total page 346 pages. Available in PDF, EPUB and Kindle. Book excerpt: [Beta]-Hydroxyperoxyl radicals are formed during atmospheric oxidation of unsaturated volatile organic compounds (VOCs) such as isoprene. They are also important intermediates in the combustion of alcohols. In these environments the unimolecular isomerisation and decomposition of [beta]-hydroxyperoxyl radicals may be of importance. Results of ion-trap mass spectrometry generating a prototypical distonic charge-tagged [beta]-hydroxyalkyl radical anion •CH2C(OH)(CH3)CH2C(O)O- have been obtained by a collaborating research group. The subsequent reaction of the radical anion with O2 in the gas phase has been investigated under conditions that are devoid of complicating radical-radical reactions. In this thesis, quantum chemical calculations and master equation/RRKM theory modelling are used to rationalise the results and discern a reaction mechanism. Reaction is found to proceed via initial hydrogen abstraction from the [gamma]-methylene group and [beta]-hydroxyl group, with both reaction channels eventually forming isobaric product ions due to loss of either •OH + HCHO or •OH + CO2. Isotope labelling studies confirm that a 1,5-hydrogen shift from the [beta]-hydroxyl functionality results in a hydroperoxyalkoxyl radical intermediate that can undergo further unimolecular dissociation. Furthermore, facile decomposition of [beta]-hydroxyperoxyl radicals has been confirmed to yield •OH in the gas phase. Moreover, the influence of an anionic charge on the reaction chemistry of [beta]-hydroxyperoxyl radicals has been investigated by examining the molecular orbitals of a distonic [beta]-hydroxyperoxyl radical anion analogue •OOCH2CH(OH)CH2C(O)O-. Instead of following the conventional Aufbau principle, the radical anion exhibits a peculiar electronic arrangement, where the singly occupied molecular orbital (SOMO) is no longer the frontier orbital and carries energy lower than other doubly occupied molecular orbitals (HOMOs). This phenomenon is manifested as SOMO-HOMO conversion and is caused by the through space stabilisation between the interaction of the anion and radical site. Further investigation of the other C4H6O5•- isomers involved in the unimolecular reaction mechanisms of the hydroxyperoxyl radical anion •OOCH2CH(OH)CH2C(O)O- revealed that these radical anion isomers exhibit different extent of orbital conversion. As a result, the reaction chemistry of this radical anion is influenced by various additional stabilities associated with the unconventional electron arrangement, switching the dominant reaction pathway from [beta]-OH abstraction in the relevant neutral radical to C-H abstraction at the [beta]-carbon in the radical anion analogue. Despite the change in product distribution, all reaction pathways remain the same in both the neutral radical and radical anion analogues. Enols are emerging as trace atmospheric components that may play a significant role in the formation of organic acids in the atmosphere. They are unsaturated VOCs and their oxidation involves hydroxyperoxyl radicals as key intermediates. It has recently been discovered that acetaldehyde can undergo UV-induced isomerisation to vinyl alcohol (the enol counterparts) under atmospheric conditions. The •OH-initiated oxidation chemistry of vinyl alcohol has been investigated in this thesis, using quantum chemical calculations and energy-grained master equation simulations. The reaction proceeds by •OH addition at both the [alpha]-carbon (66%) and [beta]-carbon (33%) of the [pi] system, yielding the C-centred radicals •CH2CH(OH)2 and HOCH2C•HOH respectively. Subsequent trapping by O2 leads to the respective peroxyl radicals. About 90% of the chemically activated population of the major peroxyl radical adduct •O2CH2CH(OH)2 is predicted to undergo fragmentation to produce formic acid and formaldehyde, with regeneration of •OH. The minor peroxyl radical CH2(OH)CH(OH)O2• is even less stable and almost exclusively undergoes HO2• elimination to form glycolaldehyde. The •OH-initiated oxidation of vinyl alcohol ultimately leads to three main product channels, being (i) •O2CH2CH(OH)2 (8%), (ii) HC(O)OH + HCHO + •OH (56%) and (iii) HOCH2CHO + HO2• (37%). This study supports previous findings that vinyl alcohol should be rapidly removed from the atmosphere by reaction with •OH and O2, with glycolaldehyde being identified as a previously unconsidered product. Moreover, it is also shown that direct chemically activated reactions can lead to •OH and HO2• (HOx) recycling. Following the study on the acetaldehyde-vinyl alcohol pair, the photo-isomerisation of glycolaldehyde to 1,2-ethenediol has been studied. The keto-enol isomerisation is associated with a barrier of 66 kcal mol-1 and involves a double hydrogen shift mechanism to give the lower energy Z isomer. This barrier lies below the energy of the UV/Vis absorption band of glycolaldehyde and is also considerably below the energy of the products resulting from photolytic decomposition. The atmospheric oxidation of 1,2-ethenediol by •OH is initiated by radical addition to the [pi] system to give the •CH(OH)CH(OH)2 radical, which is subsequently trapped by O2 to form the peroxyl radical •O2CH(OH)CH(OH)2. According to kinetic simulations, collisional deactivation of the latter is negligible and cannot compete with rapid fragmentation reactions, which lead to (i) formation of glyoxal hydrate and HO2• through an [alpha]-hydroxyl mechanism (96%) and (ii) two molecules of formic acid with release of •OH through a [beta]-hydroxyl pathway (4%). The lifetime of the two enols in the presence of tropospheric levels of •OH is determined to be around 4 hours and 68 hours respectively. Phenomenological rate coefficients for these two oxidation reactions are obtained for use in atmospheric chemical modelling. Finally, photo-induced dissociation and isomerisation of other common tropospheric carbonyl compounds, namely methyl vinyl ketone (MVK) and methacrolein (MACR), has been reinvestigated. The reaction of both molecules proceeds through dissociation, cyclisation and hydrogen shift (including keto-enol isomerisation) pathways. From the simulation of reaction dynamics, MACR photolysis is significantly less efficient than MVK photolysis, which is consistent with the experimental data in the literature. Isomerisation dominates dissociation in the actinic spectrum at longer wavelengths for both MVK and MACR photolysis. The total photolysis rate of MVK and MACR is calculated to be 3.8 x 10-5 s-1 and 8.6 x 10-7 s-1 respectively. The study reveals that MVK and MACR photolysis may lead to formation of new atmospheric VOCs such as hydroxylbutadiene from MVK and dimethylketene from MACR.

Download or read book Study of the Hydroxyl Radical Initiated Photooxidation of Volatile Organic Compounds and the Application of These Reactions written by Clifford Koenig and published by . This book was released on 2002 with total page 174 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book International Journal of Chemical Kinetics written by and published by . This book was released on 1993 with total page 620 pages. Available in PDF, EPUB and Kindle. Book excerpt: Topics covered in this publication include quantitative relationships between molecular structure and chemical activity, organic/inorganic chemistry, biochemical kinetics, and reaction mechanisms. Surface kinetics are also explored.

Download or read book Volatile Organic Compounds in the Atmosphere written by Ralf Koppmann and published by John Wiley & Sons. This book was released on 2008-04-15 with total page 512 pages. Available in PDF, EPUB and Kindle. Book excerpt: Every day, large quantities of volatile organic compounds (VOCs) are emitted into the atmosphere from both anthropogenic and natural sources. The formation of gaseous and particulate secondary products caused by oxidation of VOCs is one of the largest unknowns in the quantitative prediction of the earth’s climate on a regional and global scale, and on the understanding of local air quality. To be able to model and control their impact, it is essential to understand the sources of VOCs, their distribution in the atmosphere and the chemical transformations which remove these compounds from the atmosphere. In recent years techniques for the analysis of organic compounds in the atmosphere have been developed to increase the spectrum of detectable compounds and their detection limits. New methods have been introduced to increase the time resolution of those measurements and to resolve more complex mixtures of organic compounds. Volatile Organic Compounds in the Atmosphere describes the current state of knowledge of the chemistry of VOCs as well as the methods and techniques to analyse gaseous and particulate organic compounds in the atmosphere. The aim is to provide an authoritative review to address the needs of both graduate students and active researchers in the field of atmospheric chemistry research.