GC determination of volatile organoiodine and organobromine compounds in Arctic seawater and air samples

Summary During September 1992 seawater and air samples were collected on Spitzbergen, Norway, and the concentrations of volatile organoiodine and organobromine compounds of biogenic origin were determined by a GC system supplied with a capillary column and an electron capture detector. A purge and trap technique was used to isolate the organohalogen compounds from the seawater samples, whereas the air samples were collected by an adsorption tube filled with Carbosieve S-III. The iodinated compounds CH₃I, CH₂I₂, CH₂C1I, CH₃CH₂CH₂I and CH₃CHICH₃ were determined in Arctic seawater and air samples with mean concentrations in the range of (0.3–6.2) ng/l and (0.7–2) pptv, respectively. This is the first time that 1- and 2-propyl iodide could be analysed both in atmospheric samples and in seawater samples of the Arctic. CH₂Br₂, CHBr₃, CH₂BrCl, CHBrCl₂ and CHBr₂Cl were determined as biogenic brominated methanes in mean concentrations of (0.1–164) ng/l and (0.1–0.5) pptv in seawater and air samples, respectively. The highest concentrations in seawater samples were found for CH₂I₂ and CHBr₃, respectively, whereas in air samples the most abundant iodinated compound was CH₃I and the most abundant brominated compounds with equal mean concentrations were CH₂Br₂ and CHBr₃. Significant differences were found in the seawater concentration from the middle of the fjord and the shore site, compared with samples from a field of algae. In all cases the concentration was higher for the samples from the field of algae with an especially high excess by a factor of 4–9 for CH₂I₂ and CHBr₃. This result shows that algae are an important biological species in the polar region for the production of these halogenated substances. Whereas the brominated compounds in seawater samples correlate well with each other, CH₃I or any other iodinated compound does not correlate with the bromomethanes. This indicates a different biogenic mechanism for their formation. Under certain preconditions the annual flux from the Arctic Ocean to the atmosphere could be calculated for CH₃I to be 4×10⁹ g, for CHBr₃ to be 5.4×10¹⁰ g, which is an essential contribution to the total global budget of these important atmospheric trace gases.Dedicated to Professor Dr. Wilhelm Fresenius on the occasion of his 80th birthday     

Reaction of α,α,ω-trichloro- and α,α,α,ω-tetrachloroalkanes with alkali metal acylates in aprotic solvents

Polychloroalkanes and -alkenes R(CH₂)_nCl (R=CHCl₂CH₂, CCl₂=CH, n=1, 3) in dipolar aprotic solvents — dimethylformamide (DMF), dimethylsulfoxide (DMSO), hexamethylphosphoramide (HMPA) — at 130–150°C react selectively at the CH₂Cl group with salts of carboxylic acids RCO₂K(Na) to form dichloroesters RCO₂· (CH₂)_nR (R=CHCl₂CH₂, CCl₂=CH). In tetrachloroalkanes CCl₃CH₂(CH₂)_nCl (n = 1, 3, 5) under the same conditions the selectivity of the CCl₃ and CH₂Cl groups relative to the nucleophile RCO₂K(Na) is altered — unsaturated esters RCO₂(CH₂)_nCH=CCl₂ are formed in one stage with yields of 75–90%. Under the selected conditions, high conversion of polychloroalkanes to esters is attained 3 to 5 times more rapidly than in acid media. The structure of the ester obtained has been confirmed by their PMR spectra.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2790–2793, December, 1990.     

Kinetics and mechanism of the pyrolysis of 1-chloro-1,1-difluoroethane in the presence of additives

The thermal dehydrochlorination CF₂ClCH₃→CF₂(DOUBLEBOND)CH₂+HCl has been studied in a static system between 597 and 664 K in the presence of CCl₄, C₂Cl₆, CF₂(DOUBLEBOND)CH₂, HCl, and CF₃CH₃. A kinetic radical and molecular reaction model has been developed. In addition to describing earlier results on the acceleration of the pyrolysis by CCl₄ and the further acceleration by HCl, this model describes quantitatively up to conversions of 20% (i) the dependence of the catalytic effect of CCl₄ at low concentrations, (ii) the stronger catalytic effect of C₂Cl₆, and (iii) the inhibitory effect of added CF₂CH₂ and CF₃CH₃ when CCl₄ is used as a catalyst. © 1998 John Wiley & Sons, Inc. Int J Chem Kinet 30: 359–366, 1998     

Simultaneous measurements of formaldehyde and ozone in air by annular denuder-HPLC techniques

Summary A denuder sampling method combined with HPLC analysis for the simultaneous determination of formaldehyde and ozone in ambient air is described. It is based on the reactions of CH₂O and O₃ with 2,4-dinitrophenylhydrazine (DNPH) and 4-allyl-2-methoxyphenol (eugenol)_respectively, both acting as coatings of two annular denuders connected in series. Formaldehyde released from the ozonolysis of eugenol is quantitatively collected on a third downstream DNPH-coated denuder. The two DNPH denuders are then extracted and analyzed as hydrazone derivative by HPLC with UV absorbance detection.The stoichiometric factor of the eugenol-ozone reaction was found to be 2.0±0.1 moles of O₃ per mole of CH₂O. The limits of detection are 0.8gm^–3 CH₂O and 3gm^–3 O₃ for 100l air sampled, corresponding to 1-h sampling at 1.7l min^–1.     

Absorption of CH3 131I in various solutions from air

Procedures and results of CH₃ ¹³¹I absorption in water and ethanol solutions have been studied. These are: 1%, 5%, 15%, 30%, 50% or saturated solutions Na₂S₂O₃, C₆H₅–OH, Hg₂(NO₃)₂, AgNO₃, K₄(Fe(CN)₆), KI, NaOH, KOH and (COOH)₂. Methyl iodide was carried with the laboratory air stream through five bubblers filled with a selected solution. The CH₃ ¹³¹I released from the last bubbler was absorbed in 2 cartridges in series filled with 5% TEDA impregnated charcoal. Efficiency of CH₃ ¹³¹I absorption was studied in dependences of the kind of solutions, their concentrations, order of bubblers and CH₃ ¹³¹I concentration in the carrier air. Results of these experiments are discussed.     

Amines containing the CCl3 group and their basic dissociation constants

Summary Dissociation constants were measured for amines of the series CCl₃(CH₂)nNH₂, in which n=1–4, and for amines of the series CCl₂=CH(CH₂)nNH₂, in which n=1 and 2.     

Radical addition of polychloromethanes toα,α-dichlorovinyl compounds

Conclusions The reaction of CCl₄ and CHCl₃ with CCl₂=CHR, where R=(CH₂)₃H (I) and (CH₂)₃Cl (II), gives compounds of type HCCl₂CH(CCl₃)R, and the adducts HCCl₂CH(CCl)₂CH₂CH₂CH₂Cl (V) from (I) and HCCl₂CH·(CCl₃)CH₂CH₂CHCl₂ (VIII) from (II).From CCl₄ and CC1₂=CHCH₂CH₂CH=CH₂, besides the usual addition product CCl₂=CHCH₂CH₂CHClCH₂· CCl₃, is formed 1,1-dichloro-2-(trichIoromethyl)-5-(chloromethyl)cyclopentane due to stabilization of the CCl₂CH(CCl₃)R radical by intramolecular addition to the CH=CH₂ group and the subsequent cleavage of chlorine.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1569–1574, July, 1975.     

The vertical distribution of halocarbons in the stratosphere

Summary By means of cryogenic sampling and subsequent gas-chromatographic analysis vertical profiles of CCl₄, CCl₃F, CCl₂F₂, CClF₃, CF₄, C₂Cl₃F₃, C₂Cl₂F₄, C₂ClF₅, C₂F₆, CH₃Cl and CH₃CCl₃ were derived for stratospheric heights up to 35 km. Vertical profiles of halocarbons computed by means of one-dimensional and two-dimensional models fall off less rapidly in the stratosphere than the measured profiles, this systematic discrepancy being due to deficiencies in the radiation and transport schemes of present models. It is shown that measured profiles of fully halogenated hydrocarbons provide a tool for systematically studying these deficiencies and thus improving the models. Sources and sinks of halocarbons are discussed, and an assessment of past and future sources of organically bound chlorine in the atmosphere is made.

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Die vertikale Verteilung halogenierter Kohlenwasserstoffe in der stratosphäre

Zusammenfassung Die vertikalen Profile von CCl₄, CCl₃F, CCl₂F₂, CClF₃, CF₄, C₂Cl₃F₃, C₂Cl₂F₄, C₂ClF₅, C₂F₆, CH₃Cl und CH₃CCl₃ wurden für stratosphärische Höhen bis zu 35 km mit Hilfe kryogener Probenahme und anschließender gas-chromatographischer Analyse bestimmt. Die mit Hilfe von ein- und zweidimensionalen Modellen berechneten Profile fallen in der Stratosphäre weniger schnell ab als die gemessenen. Dieser systematische Unterschied ist auf Mängel in den Strahlungs- und Transportmechanismen der gegenwärtigen Modelle zurückzuführen. Es wird gezeigt, daß die gemessenen Profile der vollhalogenisierten Kohlenwasserstoffe dazu dienen können, diese Mängel zu untersuchen und die Modelle zu verbessern. Ursprung und Verbleib der halogenierten Kohlenwasserstoffe werden beschrieben und vergangene und zukünftige Quellen organisch gebundenen Chlors in der Atmosphäre diskutiert.

     

Determination of aliphatic amines in air by membrane enrichment directly coupled to a gas chromatograph

Summary A method is described for the determination of shortchain aliphatic amines in ambient air based on impinger sampling in dilute H₂SO₄, selective enrichment across a PTFE gas membrane and quantification by gas chromatography. The enrichment step is carried out in a flow system directly connected to the chromatograph. The separation is performed on a packed column with nitrogen selective detection. The enrichment per sample volume was in the range 7.3 to 8.2 mL^–1 for C₁–C₆ amines. Detection limits were ca 3–10 nM with enrichment of a 2.9 mL liquid sample. After impinger sampling of 5 m³ air in 10 mL absorption solution, this corresponds, to 0.4–0.8 ng/m³ (ca 0.2–0.5 ppt by volume) in air.     

Urban air pollutants and their micro effects on medieval stained glass windows

Levels of urban gaseous and particulate pollutants were investigated in the Cathedral of Cologne, Germany in the framework of the EU-project “VIDRIO”. The purpose of this study was to evaluate the influence of a protective double glazing system on the preservation of ancient stained glass windows by sampling at protected and unprotected windows (indoors, in the interspace and outdoor of the Cathedral). The interspace between the ancient stained glass window and the protective glazing is flushed in the Cathedral by indoor air, hence isolating the historic glass from the outdoor air and exposing it to indoor air on both sides of the glass panels. Concentrations of aggressive gaseous pollutants such as NO₂, SO₂, O₃ and CO₂ as well as elemental concentrations of bulk particles and relative abundances of single particles were surveyed at all sampling locations. Elemental concentrations in bulk particulate matter were found to be significantly lower inside the Cathedral in comparison to the outdoor air. This result is advantageous for the stained glass windows. Single particle analysis of the samples from Cologne showed also soil dust and organic particles as well as sulphates and nitrates, from which the latter two compounds are dangerous for the stained glass windows. On the base of the obtained results, it can be concluded that the protective glazing system in the Cathedral of Cologne can be considered as predominantly advantageous from both the gases' point of view (except for NO₂-candles burning) and from the particles' point of view.     

Reaction of α,α,ω-trichloroalkenes with 1,1,1-trichloroethane and 1,1,1,3-tetrachloropropane,accompanied by rearrangement of radicals

Conclusions In the reaction of CCl₃CH₃ with CCl₂=CHCH₂CH₂CH₂Cl, and of CCl₃CH₂CH₂Cl with CCl₂= CHCH₂Cl, initiated by Fe(CO)₅+DMF, the main addition products are respectively compounds of structure HCCl₂CH(CCl₂CH₃)CH₂CH₂CHCl₂ and HCCl₂CH(CCl₂CH₂CHCl₂)CH₂C1. The formation of these compounds was explained by the isomeriza'tion of the radical-adducts CCl₂CH(CCl₂CH₃)CH₂CH₂CH₂Cl and CCl₂CH(CCl₂CH₂CH₂Cl)CH₂Cl, with migration of a hydrogen atom from the CH₂Cl groups found in the 5 position to the radical center.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1857–1861, August, 1980.     

Reactions of recoil bromine with bromochloromethanes

Reactions of recoil^{80, 80m}Br with CH₂ClBr and CCl₃Br have been investigated. Relative reactivities of recoil bromine atoms in binary mixtures of CH₂ClBr and CCl₃Br with c–C₆H₁₂, CH₃OH and C₆H₅N/CH₃/₂ have been determined using the model developed by Kontis and Urch.     

Dissociation of Physisorbed Halomethane Molecules by KrF Excimer Laser Radiation

The competitive processes of photolysis and desorption of CF₂Cl₂, CCl₄, CHF₂Cl, CHCl₃, CH₂Cl₂, CH₂I₂, and CH₃I halomethane molecules physisorbed on fused silica were experimentally studied. These processes were induced by the absorption of high-intensity UV radiation from a KrF excimer laser by these molecules. It was shown that a common feature in the behavior of all of these compounds is nonlinear dependence of desorption on radiation intensity, typical nonlinearity indices being very high: n = 5–7. One-photon dissociation was carried out in the adsorbed state of CCl₄, CH₂I₂, and CH₃I molecules absorbing radiation with a wavelength of 248 nm and in a gas phase. The photofragments are characterized by kinetic energies lower than 0.2 eV. The multiphoton fragmentation of the adsorbed molecules was observed and discussed.     

Vibrational population lifetimes of polyatomic molecules in liquids

CH-stretching modes were first excited by picosecond infrared pulses and the generated excess population was monitored by anti-Stokes scattering of subsequent ultrashort probe pulses. Experimental data are reported on five molecules: CHCl₃, CH₂Cl₂, CH₃CCl₃, CH₃CH₂OH, and CH₃I in the neat liquid and/or in solutions of CCl₄. The observed time constants vary between 1 and 100 ps depending upon the individual molecule and surrounding. Theoretical calculations show that rotational coupling, Fermi resonance, Coriolis coupling, and resonance energy transfer can strongly effect the vibrational population lifetime. The relevance of these processes is quite different for the various molecules investigated.     

Kinetics and mechanism for the oxidation of 1,1,1-trichloroethane

The reaction mechanisms for oxidation of CH₃CCl₂ and CCl₃CH₂ radicals, formed in the atmospheric degradation of CH₃CCl₃ have been elucidated. The primary oxidation products from these radicals are CH₃CClO and CCl₃CHO, respectively. Absolute rate constants for the reaction of hydroxyl radicals with CH₃CCl₃ have been measured in 1 atm of Argon at 359, 376, and 402 K using pulse radiolysis combined with UV kinetic spectroscopy giving ??(OH + CH₃CCl₃) = (5.4 ± 3) 10^?12 exp(?3570 ± 890/RT) cm³ molecule^?1 s^?1. A value of this rate constant of 1.3 × 10^?14 cm³ molecule^?1 s^?1 at 298 K was calculated using this Arrhenius expression. A relative rate technique was utilized to provide rate data for the OH + CH₃ CCl₃ reaction as well as the reaction of OH with the primary oxidation products. Values of the relative rate constants at 298 K are: ??(OH + CH₃CCl₃) = (1.09 ± 0.35) × 10^?14, ??(OH + CH₃CClO) = (0.91 ± 0.32) × 10^?14, ??(OH + CCl₃CHO) = (178 ± 31) × 10^?14, ??(OH + CCl₂O) < 0.1 × 10^?14; all in units of cm³ molecule^?1 s^?1. The effect of chlorine substitution on the reactivity of organic compounds towards OH radicals is discussed.     

Analysis of sulfur-containing compounds in ambient air using solid-phase microextraction and gas chromatography with pulsed flame photometric detection

A new analysis method for sulfur-containing compounds in air using solid-phase microextraction (SPME), gas chromatography and pulsed flame photometric detection (PFPD), SPME-GC-PFPD method, has been developed. The analysis method is simple, fast and easily performed. To demonstrate the usefulness and versatility of the method air samples collected in geothermal areas in Rotorua, at a muddy beach in Auckland (cities in New Zealand), and in a wastewater treatment plant were analysed. COS, H₂S, CS₂, SO₂, CH₃SH, (CH₃)₂S and CH₃(CH₂)₂CH₂SH were identified in the samples from Rotorua. It was noted that air quality in residential areas with respect to sulfur compounds was better than that around geothermal sources. Samples from the wastewater treatment plant contained COS, H₂S, CS₂, SO₂, CH₃SH, (CH₃)₂S and (CH₃)₂S₂. It was found that the emission of sulfur compounds was reduced in the course of the wastewater treatment process. The potential impact of the detected sulfur compounds on human health is briefly discussed.     

Determination of chlorinated hydrocarbons in single and multi component test gases

Summary For comparing the efficiency of active and diffusive sampling methods two diffusive samplers with different properties were used to determine chlorinated hydrocarbons (CH₂Cl₂, CHCl₃, CCl₄) in single and multi component test gas mixtures. One of the chosen diffusive samplers can also be used for active sampling.In general, good correlations of all tested methods could be observed in the direct comparison of active and diffusive sampling and in the determination of the efficiencies.During the application of active and diffusive sampling methods in multi component test gases of the analytes possible interferences could not be ascertained.     

Radical telomerization of 3,3,3-trifluoro-1-propene with carbon tetrachloride

Telomerization of 3,3,3-trifluoropropene with CCl₄ was carried out in the presence of Fe(CO)₅ in combination with dimethylformamide (DMF) or hexamethylphoshoric triamide (HMPA) with formation of the telomers CCl₃(CH₂CHCF₃)_nCl, n=1–3, as the main products. Chromatography-mass spectrometry showed the presence of CCl₃CH₂CH(CCL₃)CF₃, a product of recombination of the adduct radical and CCl₃, in the reaction mixture, which confirms the radical nature of the process. The structure of all the reaction products was confirmed by¹³C NMR and (or) mass spectrometry.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1807–1811, August, 1990.     

Experimental and theoretical study on the structure and reactions of 1-methoxypropane radical cations

Structure and mechanism of thermal and photochemical reactions of radical cations of methyl n-propyl ether (MPE) were studied in irradiated freonic matrices CFCl₃, CF₂ClCFCl₂, and CF₃CCl₃ at 77 K. The quantum chemical calculations of the structure of radical cations and products of their transformations were carried out with methods based on the density functional theory (DFT). Experimental and calculation results show that the MPE radical cations are characterized by substantial delocalization of spin density to the propyl group. The action of light on the MPE radical cations in a CF₃CCl₃ matrix at 77 K results in intramolecular rearrangement yielding the distonic radical cation ^.CH₂CH₂CH₂(OH⁺)CH₃. It was found that the primary MPE radical cations underwent irreversible transformation to CH₃CH₂CH₂OCH ₂ ^. radical as a result of an ion-molecule reaction that occurred in a CF₂ClCFCl₂ matrix upon heating the sample to 110–120 K or in a CFCl₃ matrix upon increasing the solute concentration.Translated from Khimiya Vysokikh Energii, Vol. 39, No. 2, 2005, pp. 105–113.Original Russian Text Copyright © 2005 by Belevskii, Feldman, Tyurin.This revised version was published online in April 2005 with a corrected cover date.     

Carbon-13 NMR spectra of some polychlorinated telomerisation products

The study of 28 specially selected compounds containing chlorine shows that ¹³C NMR signals of the CCl₃, CCl₃CH₂ and CH₂Cl groups are registered in the ranges of 93 to 105, 49 to 71 and 38 to 59 ppm (from TMS), respectively and are readily identified in ¹³C NMR spectra of polychloro compounds. The weak electron withdrawing ability of the CCl₃CHCl and CH₂Cl groups, as well as the extremely strong influence of CCl₃ and CH₂Cl groups on the methylene group between them in 1,1,1,3-tetrachloropropane, is noted.