Reactions Of Organic Compounds Research Articles

Structure and Reactivity of Radical Ions: New Twists on Old Concepts

Electron transfer is the simplest reaction possible, yet it has a profound impact on the structure and reactivity of organic compounds. These changes allow a new look at some of the fundamental concepts that are used to explain organic chemistry, such as symmetry, aromaticity, and bonding. The results from high-level electronic structure calculations are used to analyze the mechanistic differences in the pericyclic reactions of simple hydrocarbons and their radical cation counterparts. The importance of state symmetry correlation, Jahn-Teller distortions, delocalization, and fractional bonding for the reaction pathways of hydrocarbon radical cations is discussed.

Characteristics of Fine Particle Growth Events Observed Above a Forested Ecosystem in the Sierra Nevada Mountains of California

Atmospheric aerosols from natural and anthropogenic processes have both primary and secondary origins, and can influence human health, visibility, and climate. One key process affecting atmospheric concentrations of aerosols is the formation of new particles and their subsequent growth to larger particle sizes. A field study was conducted at the Blodgett Forest Research Station in the Sierra Nevada Mountains of California from May through September of 2002 to examine the effect of biogenic volatile organic compounds on aerosol formation and processing. The study included in-situ measurements of concentration and biosphere-atmosphere flux of VOCs, ozone, aerosol size distribution, aerosol physical and optical properties, and meteorological variables. Fine particle growth events were observed on approximately 30 percent of the 107 days with complete size distribution data. Average particle growth rates measured during these events were 3.8 ± 1.9 nm hr−1. Correlations between aerosol properties, trace gas concentrations, and meteorological measurements were analyzed to determine conditions conducive to fine particle growth events. Growth events were typically observed on days with a lesser degree of anthropogenic influence, as indicated by lower concentrations of black carbon, carbon monoxide, and total aerosol volume. Days with growth events also had lower temperatures, increased wind speeds, and larger momentum flux. Measurements of ozone concentrations and ozone flux indicate that gas phase oxidation of biogenic volatile organic compounds occur in the canopy, strongly suggesting that a significant portion of the material responsible for the observed particle growth are oxidation products of naturally emitted very reactive organic compounds.

Determination of Four Quinones in Diesel Exhaust Particles, SRM 1649a, and Atmospheric PM2.5Special Issue ofAerosol Science and Technologyon Findings from the Fine Particulate Matter Supersites Program

Quinones are reactive organic compounds and are known to initiate reactions associated with many toxicological events. Their presence in air pollution has been demonstrated, but routine quantitative measurements are lacking. A quantitative method for the determination of four quinones was developed using diesel exhaust particles (DEP) and National Institute of Standards and Technology (NIST) Standard Reference Material (SRM) 1649a. The method was then used to analyze ambient air samples from different sites in Southern California. After extraction in dichloromethane, the target compounds were converted to their stable diacetyl derivatives and determined by electron impact GC-MS using selected ion monitoring. Calibration plots were obtained with deuterium-labeled internal standards. The four quinones, 1,2-naphthoquinone (1,2-NQ), 1,4-naphthoquinone (1,4-NQ), 9,10-phenanthraquinone (9,10-PQ), and 9,10-anthraquinone (9,10-AQ), were quantified in DEP, in SRM 1649a, and in ambient air samples of PM2.5 collecte...

A novel approach based on solid phase microextraction gas chromatography and mass spectrometry to the determination of highly reactive organic compounds in cells cultures: styrene oxide.

A solid phase microextraction (SPME) gas chromatography/mass spectrometry (GC/MS) method was developed to assess actual doses of highly reactive organic compounds like styrene oxide (SO) in exposed cell cultures. Using SPME, we set up a method to measure accurately extracellular SO concentrations as well as to obtain an approximate assessment of intracellular levels. The SPME-GC/MS method was developed and validated using two different coating materials, carboxen-PDMS and polyacrylate. In cell-free systems, linearity was established over 3 orders of magnitude for both fibers, but carboxen-PDMS showed higher extraction efficiency and a lower limit of detection (0.5 x 10(-7) vs 10(-6) M for polyacrylate). Precision calculated as % RSD was within 4-16% for all intra- and interday determinations. Experiments performed to study SO stability in cell-free medium showed a time-dependent decrease in SO concentration (11% of initial the concentration after 24 h), mostly due to the spontaneous hydrolysis of SO into styrene glycol, which was measured by liquid chromatography/tandem mass spectrometry (LC/MS/MS). When the neuronal cell line (SK-N-MC) was exposed to a nominal concentration of 0.3 x 10(-4) M SO, the actual concentration measured in the supernatant was considerably lower and was found to decrease during incubation. Intracellular SO was estimated indirectly, by difference between the amount measured in the medium without cells and in the supernatant of the cell-containing medium.

03/02148 Synthetic fuel briquet comprising coal dust, water and a reactive organic compound, and a process for making such synthetic fuel: Cutright, P. and Gambino, J. U.S. Pat. Appl. Publ. US 2003 41,509 (Cl. 44–553; C10&L1/10), 6 Mar 2003, Appl. 935,107

03/02148 Synthetic fuel briquet comprising coal dust, water and a reactive organic compound, and a process for making such synthetic fuel: Cutright, P. and Gambino, J. U.S. Pat. Appl. Publ. US 2003 41,509 (Cl. 44–553; C10&L1/10), 6 Mar 2003, Appl. 935,107

HS-SPME analysis of volatile organic compounds of coniferous needle litter

The composition of volatile emission of Scots pine (Pinus sylvestris) and spruce (Picea exelsa) litter was studied by gas chromatography-mass spectrometry (GC-MS) and samples were collected by solid-phase microextraction (SPME) method. The list of identified compounds includes over 60 organic substances of different classes. It was established that volatile emission contain not only components of essential oils of pine and spruce needles but also a large number of organic compounds which are probably secondary metabolites of litter-decomposing fungi. They include lower carbonyl compounds and alcohols as well as products of terpene dehydration and oxidation. These data show that the processes of litter decomposition are an important source of reactive organic compounds under canopy of coniferous forests.

Ground-based PTR-MS measurements of reactive organic compounds during the MINOS campaign in Crete, July–August 2001

Abstract. This study presents measurements of acetonitrile, benzene, toluene, methanol and acetone made using the proton-transfer-reaction mass spectrometry (PTR-MS) technique at the Finokalia ground station in Crete during the Mediterranean INtensive Oxidant Study (MINOS) in July-August 2001. Three periods during the campaign with broadly consistent back trajectories are examined in detail. In the first, air was advected from Eastern Europe without significant biomass burning influence (mean acetonitrile mixing ratio 154 pmol/mol). In the second period, the sampled air masses originated in Western Europe, and were advected approximately east-south-east, before turning south-west over the Black Sea and north-western Turkey. The third well-defined period included air masses advected from Eastern Europe passing east and south of/over the Sea of Azov, and showed significant influence by biomass burning (mean acetonitrile mixing ratio 436 pmol/mol), confirmed by satellite pictures. The mean toluene:benzene ratios observed in the three campaign periods described were 0.35, 0.37 and 0.22, respectively; the use of this quantity to determine air mass age is discussed. Methanol and acetone were generally well-correlated both with each other and with carbon monoxide throughout the campaign. Comparison of the acetone and methanol measurements with the MATCH-MPIC model showed that the model underestimated both species by a factor of 4, on average. The correlations between acetone, methanol and CO implied that the relatively high levels of methanol observed during MINOS were largely due to direct biogenic emissions, and also that biogenic sources of acetone were highly significant during MINOS (~35%). This in turn suggests that the model deficit in both species may be due, at least in part, to missing biogenic emissions.

Detoxification of reactive compounds by a cyclic electrolytic system with surface-modified ion-exchange resin

Electrolysis of water generates hydroxide ions at the cathode that can be used for the hydrolysis of reactive organic compounds that are used as pesticides or nerve agents. Electrolytic decomposition of reactive compounds was tested with our small-scale cyclic system that contained surface-modified ion-exchange resins with n-hexadecyl chain and 2-hydroxylethyl group. Such a system could eliminate the need for addition of cationic surfactant and catalyst for hydrolysis, while maintaining high and constant reactivity, and did not leave any remaining reactant or byproduct after hydrolysis. Comparisons among surface-modified resins are made, together with a brief discussion of the reasons for different reactivity and general application to purification of water resources.

Volatile organic compound emissions from terrestrial ecosystems: A primary biological control over atmospheric chemistry

AbstractPlants produce a variety of non‐methane volatile organic compounds (NMVOCs) that react with photochemical components of the atmosphere and influence the production of atmospheric oxidants. In this review, the case is made that biogenic NMVOC emissions exert one of the primary controls over regional and global atmospheric chemistry. The diversity of biogenic, reactive organic compounds capable of fueling atmospheric chemistry is immense, including terpenes, alcohols, aldehydes, ketones, and organic acids. Considerable effort has been devoted to the design of models capable of predicting NMVOC emission rates, and thus driving atmospheric chemistry models. Over the past decade, however, what once seemed like promising conceptual connections of NMVOC emissions to fundamental biochemical processes such as photosynthesis, have not been realized; this has delayed the development of mechanistic NMVOC emissions models. Future progress in this area will require new subcellular experimental systems, and the biochemical insight that will accompany these investigations. The past use of existing coupled biogenic emission—photochemistry models at the global scale, even with their mechanistic limitations, has revealed the potential for NMVOC emissions from terrestrial ecosystems to cause reductions in tropospheric hydroxyl radical concentration and increases in the concentration and lifetime of radiatively important trace gases such as methane and ozone.

Volatile organic compounds from leaves litter.

Qualitative composition of volatile emissions of litter of five species of deciduous trees was investigated by GC-MS. The list of identified substances contains more than 70 organic compounds of various classes. It was established that the composition of components emitted by the litter into the gas phase greatly differs from that of essential oils extracted by hydrodistillation from turned leaves collected from trees during fall. It is suggested that most compounds found in litter emissions are products of vital activity of microorganisms decomposing it. The reported data indicate that after the vegetative period is over the decomposition processes of litter are important seasonal sources of reactive organic compounds under the forest canopy.

Glutathione S-transferase pi expression in forestomach carcinogenesis process induced by gavage-administered 2,4-hexadienal in the F344 rat.

2,4-Hexadienal (2,4-Hx), an unsaturated aldehyde formed by in vivo and in vitro peroxidation of unsaturated lipid induced, in National Toxicology Program (NTP) gavage studies of F344 rats, forestomach hyperplasia in 13-week and 2-year exposures and squamous papilloma and carcinoma in 2-year studies. Hyperplasia was characterized by thickening of all layers of epithelium with particularly prominent proliferation of the basal cells. The present investigation describes the nature and potential significance of glutathione-S-transferase-Pi (GST-Pi) immunoexpression of normal forestomach epithelium, compared to that of 2,4-Hx-related basal cell hyperplasia and squamous cell papilloma and carcinoma. Paraffin-embedded forestomachs from these NTP studies were used to investigate possible correlations between the carcinogenic process and expression of GST-Pi, a physiological metabolic barrier and an inducible phase II detoxifying enzyme suggested to decrease the responsiveness of reactive oxygen species (ROS) and organic electrophilic compounds. The amount of immunopositive staining was graded on a scale of 0 (no staining) to 4 (marked staining). The simple basal epithelium of control rats showed strong immunopositivity. In cases of basal cell hyperplasia from the 13-week and 2-year studies, these cells usually expressed strong immunopositivity for GST-Pi (grade 3 to 4). In the 2-year treated animals only, occasional focal reduction (grade 0 to 2) in immunoreactivity for GST-Pi was noted. In papillomas and squamous cell carcinomas, a wide range of GST-Pi expression was observed, perhaps indicating irregularities in its induction or change in the phenotype of these cells compared to normal or hyperplastic ones. Reduced expression of GST-Pi by the foci of basal cell hyperplasia and in tumor cells may suggest changes in cellular protection from oxidative or electrophilic DNA damage; these changes may result in genetic alterations and be the precursor to clonal expansion.

ChemInform Abstract: Reactivity of Organic Compounds in Superheated Water: General Background

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Reactivity of organic compounds in superheated water: general background.

Reactivity of organic compounds in superheated water: general background.

The Synthesis of Silicon-containing Polyester Directly from SiO2 and Characterization of Its Structure

ABSTRACTA new approach to the synthesis of a novel silicon-containing polyester by noncarbothermal method directly from SiO2 was studied. At first, a high reactive pentacoordinate organic silicon compound (KSi(OCH2CH2O)2(OCH2CH2OH)) was prepared by the reaction of the fumed silica with ethylene glycol (EG) and KOH. Then, a novel double hydroxy tetracoordinate silicon monomer (OCH2CH2O)Si(OCH2CH2OH)(OCH2CH2OCH2CH2OH) was synthesized by the reaction of ClCH2CH2OH with reactive pentacoordinate silicon compound. Finally, a silicon-containing polyester was synthesized by low temperature solution condensation between tetracoordinate silicon compound and p-phthaloyl chloride in dimethyl sulfoxide (DMSO). The product was characterized by FTIR, TG, GPC, etc. The IR spectra of polyester exhibited a characteristic strong absorption band for ester carbonyl in the 1722.2cm-1. IR spectra also showed absorption at 1124.6cm-1 due to the O-Si-O group. TG analysis showed its good thermal stability. GPC analysis showed that the number average molecular weight of this siliconcontaining polyester was about ninety thousand.

From Cyclic Voltammetry to Scanning Electrochemical Microscopy: Modern Electroanalytical Methods to Study Organic Compounds, Materials, and Reactions

This review shows some recent developments in the use of electroanalytical methods in the context of organic electrochemistry. Several techniques (cyclic voltammetry, spectroelectrochemistry, electrochemical quartz microgravimetry, and scanning electrochemical microscopy) for elucidation of properties and reactivity of organic compounds and materials are discussed. Such techniques also allow the detailed analysis of electron transfer initiated chemical reactions. Advantages added by techniques not only recording current-potential-time relationships, but including spectral, mass, and spatial information are pointed out. Thus, structures of redox active or electron transfer generated species become accessible, properties of surface bound and deposited molecules can be determined, and lateral resolution for both, analysis of the chemical nature of electrode surfaces, and induction of reactions on electrodes is provided.

Automated Sequential Sampler for Collection of Highly Volatile Atmospheric Contaminants

AbstractRapid and accurate measurement of atmospheric concentrations of highly volatile organic compounds is important in obtaining reliable information for the assessment of environmental pollution or the volatilization mechanisms of the chemicals. Nonmechanized sample collection requires intensive labor and effort, and may cause large random or systematic errors. An automated solenoid switching system was developed to assist in obtaining precise environmental concentrations of highly volatile organic compounds. The design, construction, and operation are described in the paper for potential application in similar studies. Using this sampling system, two experiments were conducted to determine atmospheric volatilization flux density of three highly volatile and reactive organic compounds (methyl bromide, 1,3‐dichloropropene, and propargyl bromide). The automated solenoid switching system significantly reduced the requirements for labor and time. Results from the two experiments indicate that reliable sample collection was achieved. The automated sampling system was also relatively inexpensive and can be easily modified to accommodate a variety of sources, sampling intervals, and multiple number of solenoid valves.

Reactivity of aromatic compounds toward diphenylcarbonyl oxide

The reactivity of organic compounds (PhH, PhMe, PhF, PhCl, PhOH, PhOEt, PhCHO, Ph2CO, PhCN, Ph2S, Ph2SO, Ph2SO2, andp-Me2C6H4) toward diphenylcarbonyl oxide Ph2COO was characterized by thek33/k31 ratio, wherek33 andk31 are the rate constants for the reactions of Ph2COO with the arene and diphenyldiazomethane Ph2CN2, respectively. The values ofk33/k31 vary from 2.6·10−3 (PhCN) to 0.65 (Ph2S) (70°C, MeCN). The reaction is preceded by formation of a complex with charge transfer from a substrate to Ph2COO. In the reactions with aromatic substances (except for Ph2SO, PhCHO, and Ph2CO), carbonyl oxide behaves as an electrophile.

Molecular indicators of diagenetic status in marine organic matter

The fluxes of individual carbohydrates, amino acids, lipids and pigments have been determined in net-plankton, particulate matter and sediments from three sites (9°N, 5°N, and 0°N) in the central equatorial Pacific to evaluate sources and reactivities of organic compounds. Although primary production rates vary markedly across this 9° swath, vertical trends in biochemical compositions remained remarkably parallel. Together these one hundred plus biochemicals account for 80% of the total organic carbon (C org) in net-plankton and particles sinking from the euphotic zone, but represent only 24 and 20% of the organic carbon in deep-water particles and surface sediments, respectively. Scaled profiles of relative abundances, clearly illustrate (a) exponential losses of plankton remains and increases in heterotroph biomarkers throughout the water column, (b) elevated proportions of bacterial markers near the sediment surface, and (c) preservation of selected remains of bacteria, phytoplankton and vascular land plants deeper in the sediments. In spite of one of the most comprehensive analyses of major biochemicals yet applied to marine particulate samples, percentages of molecularly uncharacterized organic carbon increase progressively down the water column to values near 80% in the underlying sediments. The composition, formation pathway and information potential of this uncharatterized fraction are among the most fascinating questions in marine organic geochemistry.

Emissions of organic trace gases from savanna fires in southern Africa during the 1992 Southern African Fire Atmosphere Research Initiative and their impact on the formation of tropospheric ozone

CO, CH4, and organic trace gases were measured in air samples collected during several flights with a DC‐3 aircraft through the plumes from savanna fires and agricultural fires during the SAFARI 92 campaign in southern Africa in September and October 1992. In all samples a variety of higher molecular weight organic compounds was found, most of which are very reactive. More than 70 of the roughly 140 major components present could be identified. Typically, mixing ratios of several hundred parts per billion carbon of organic compounds were measured inside the plumes, corresponding to an emission ratio of total organic carbon relative to CO2of up to 1%. About 50% of these emissions were in the form of oxygenated and unsaturated compounds. The contributions of still unknown compounds to the total emission of organic compounds add up to another 20–30%. The observed emission ratios relative to CO2show a considerable variation depending on the fuel type and the burning stages of the fire. The lowest value of the emission ratio of the sum of all identified organic compounds relative to CO2was found for a sugar cane fire with (1.7±0.7)×10−3(ppb C/ppb CO2). For a large savanna fire in Kruger National Park the ratio was (7.4±1.6)×10−3(ppb C/ppb CO2). The highest value was (13.7±0.9)×10−3(ppb C/ppb CO2) for an uncontrolled fire of mainly wood and shrub in the Drakensberg region. Results of model calculations show that in biomass‐burning plumes, reactive organic compounds contribute significantly to the formation of ozone, especially during the initial phase of photochemical processing.

Wastewater derived interferences in cyanide analysis

Common, cellulose-derived and other naturally occurring organics which are likely to be present, or generated in wastewater discharges were evaluated. During cyanide analyses, reactive organic compounds produced CN − in samples containing oxidized nitrogen ions. The study showed that oxidized nitrogen species (NO − 2 and NO − 3) can be generated when hypochlorite or hydrogen peroxide is added to ammonia solutions. Under the conditions existing during cyanide analysis, nitrate and nitrite ions are converted to nitric and nitrous acid respectively. These acids react with organic molecules present in solution to form intermediate oximes, nitro-alkanes, hydroxamic acids and other transient compounds which are unstable in hot, strongly acidic environments. The thermally oxidatively labile intermediates break down to produce CN − and other degradation products. Some condensation of nitrogen oxides with organics in solution may occur prior to distillation, since addition of sulfamic acid to samples in the study did not completely eliminate all cyanide formation. The formation of these labile intermediates is greatly reduced, however, when NO x is removed by sulfamic acid prior to distillation. This study revealed the general nature of these cyanide forming reactions with common hydroxyl, poly-hydroxyl, aldehyde, ketone and other functional groups.