Biogenic volatile organoiodine and organobromine hydrocarbons in the Atlantic Ocean from 42°N to 72°S

During the cruise ANT X/1 and 2 of the research vessel Polarstern from November 1991 to March 1992, 39 surface water samples of the Atlantic Ocean from 42°N to 72.5°S were collected and analysed for their concentration of volatile iodinated and brominated hydrocarbons. The concentration of chlorophyll-a was used as an indicator for phytoplankton, which is one of the main producers of iodinated and brominated compounds in the ocean. For determination of chlorophyll-a, fluorescence spectroscopy was applied, whereas the measurement of halogenated volatile hydrocarbons was carried out by a purge and trap system with subsequent gas chromatographic separation and detection by an electron capture detector. With this technique the brominated substances CHBr₃, CH₂Br₂, CHBr₂Cl and CHBrCl₂ have been detected in the range of <0.03?ng/L to 15?ng/L. For these volatile bromomethanes a distinct concentration profile was found. CHBr₃ was always found to be the substance with the highest concentration followed by CH₂Br₂, CHBr₂Cl and CHBrCl₂. It could also be shown that in addition to CH₃I, which for a long time was believed to be the only volatile iodinated substance in the marine environment, other iodinated substances like CH₂ClI, CH₂I₂ and CH₃CH₂CH₂I exist in the range of <0.01?ng/L to 2.2?ng/L in surface water of the Atlantic Ocean. Although it is improbable that chlorophyll-a is directly involved in the marine production of halogenated hydrocarbons, it was found that it could be used as an indicator for the biogenic formation of brominated compounds, whereas the correlation between chlorophyll-a and the iodinated substances was not of the same quality. The positive correlation between bromoform and dibromomethane proves the same biogenic origin and mechanism of formation, which could not be found for the different iodinated compounds.     

Kinetics of the R + HBr RH + Br (CH3CHBr, CHBr2 or CDBr2) equilibrium. Thermochemistry of the CH3CHBr and CHBr2 radicals

The kinetics of the reaction of the CH₃CHBr, CHBr₂ or CDBr₂ radicals, R, with HBr have been investigated in a temperature-controlled tubular reactor coupled to a photoionization mass spectrometer. The CH₃CHBr (or CHBr₂ or CDBr₂) radical was produced homogeneously in the reactor by a pulsed 248 nm exciplex laser photolysis of CH₃CHBr₂ (or CHBr₃ or CDBr₃). The decay of R was monitored as a function of HBr concentration under pseudo-first-order conditions to determine the rate constants as a function of temperature. The reactions were studied separately from 253 to 344 K (CH₃CHBr + HBr) and from 288 to 477 K (CHBr₂ + HBr) and in these temperature ranges the rate constants determined were fitted to an Arrhenius expression (error limits stated are 1σ + Student’s t values, units in cm³ molecule⁻¹ s⁻¹, no error limits for the third reaction): k(CH₃CHBr + HBr) = (1.7 ± 1.2) × 10⁻¹³ exp[+ (5.1 ± 1.9) kJ mol⁻¹/RT], k(CHBr₂ + HBr) = (2.5 ± 1.2) × 10⁻¹³ exp[−(4.04 ± 1.14) kJ mol⁻¹/RT] and k(CDBr₂ + HBr) = 1.6 × 10⁻¹³ exp(−2.1 kJ mol⁻¹/RT). The energy barriers of the reverse reactions were taken from the literature. The enthalpy of formation values of the CH₃CHBr and CHBr₂ radicals and an experimental entropy value at 298 K for the CH₃CHBr radical were obtained using a second-law method. The result for the entropy value for the CH₃CHBr radical is 305 ± 9 J K⁻¹ mol⁻¹. The results for the enthalpy of formation values at 298 K are (in kJ mol⁻¹): 133.4 ± 3.4 (CH₃CHBr) and 199.1 ± 2.7 (CHBr₂), and for α-C–H bond dissociation energies of analogous compounds are (in kJ mol⁻¹): 415.0 ± 2.7 (CH₃CH₂Br) and 412.6 ± 2.7 (CH₂Br₂), respectively.     

Reaction of 3,3,3-trifluoropropene-1 with bromoform and methylene bromide

The radical telomerization of 3,3,3-trifluoropropene with bromoform and methylens bromide has been studied. The nature of the products with bromoform depends substantially on the method of initiation. In the presence of Fe(CO)₅ + DMF, telomers of CHBr₂(CH₅₂CHCF₃)_nBr are formed, while with initiation with benzoyl peroxide other compounds are also formed that contain two, three, or four bromine atoms per molecule. To elucidate the formation of these products a reaction scheme is proposed that involves rearrangement of CHBr₂CH₂CH(CF₃)CH₃CHCF₃ radicals to CBr₂CH₂CH(CF₃)CH₂CH₂CF₃ radicals.Deceased.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2558–2562, November, 1989.     

The structure of the mineralomimetic cadmium cyanide-dimethyl carbonate clathrate

Cd(CN)₂·(CH₃O)₂CO (1) contains a mineralomimetic framework of Cd(CN)₂ analogous to the low temperature form of cristobalite. The host framework is isostructural to those of previously reported Cd(CN)₂·G compounds (G = CHCl₂CH₂Cl2, (CH₃)₂CHBr3). The dimethyl carbonate molecules in the adamantane-like cage display orientation disorder associated with the location of the carbonyl oxygen atom.Presented at the Sixth International Seminar on Inclusion Compounds, Istanbul, Turkey, 27–31 August, 1995.     

The formation of clathrate-like hydrates of tetrabutylammonium halogenated carboxylates

The solid-liquid phase diagrams of binary mixtures of tetrabutylammonium halogenated carboxylates with water were examined in order to confirm the formation of clathrate-like hydrates. It was found that, among thirteen carboxylates examined, four carboxylates having CH₂FCOO^–, CHF₂COO^–, CF₃COO^–, and CH₂ClCOO^–, formed a hydrate with hydration numbers around 30 and seven carboxylates having CHCl₂COO^–, CCl₃COO^–, CH₂BrCOO^–, CHBr₂COO^–, CBr₃COO^–, CH₃CHClCOO^–, and CH₃CHBrCOO^– formed a hydrate with hydration numbers around 23. The latter hydrate has not been reported earlier. The melting points of these newly found hydrates were fairly high: they lie between 10 and 16°C. The effect of Cl and Br atoms attached to the carbon atom of the-position of a carboxylate anion both on the type of hydrate formed and on its stability was greatly different from that of a CH₃ group attached to the same position of the carboxylate anion.Dedicated to Dr D. W. Davidson in honor of his great contributions to the sciences of inclusion phenomena.     

Functionalization of saturated hydrocarbons by aprotic superacids 4. Ionic bromination of ethane and other alkanes and cycloalkanes with molecular bromine in the presence of systems based on polyhalomethanes and AlBr3 under mild conditions

Aprotic organic superacids CBr₄ · 2AlBr3, CBr₄ · AIBr₃, CHBr₃ · 2AlBr₃, CCl₄ · 2AlBr3, and C₆F₅CF₃ -2AlBr3 efficiently catalyze the bromination of alkanes and cycloalkanes with Br₂. Ethane is selectively brominated at 55–65 °C to give mostly 1,2-dibromoethane (stoichiometric reaction). Propane, butane, cyclopentane, cyclohexane, and methylcyclopentane react with Br₂ at -40 to -20 °C with good selectivity affording monobromides in high yields (catalytic reactions).Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1208–1213, May, 1996.     

On the role of solvent in complexation equilibiria. II. The acid-base chemistry of some sulfhydryl and ammonium-containing amino acids in water—acetonitrile mixed solvents

The macroscopic and microscopic acid-base chemistry of a series of sulfhydryl and ammonium-containing amino acids HS–R–NH₃ [R=–CH₂CH(COOH)–, cysteine (CYS); R=–C(CH₃)₂CH(COOH)–, penicillamine (PEN); R=–CH(COOH)CH₂CH₂CONHCH(–CH₂)CONHCH₂COOH, glutathione (GSH)] was characterized in water and its binary mixtures with acetonitrile (16.3, 34.2, and 53.9 mass % acetonitrile). Macroscopic acid dissociation constants were obtained by potentiometric titration using the glass-calomel electrode pair. Microscopic acid dissociation constants were calculated from ultraviolet absorption measurements at ca. 232 nm where the deprotonated sulfhydryl group absorbs. The macroscopic constants decrease uniformly as the solvent becomes enriched in acetonitrile. The microscopic constants, which characterize the relative concentrations of the two monoprotonated tautomers of the molecules (I and II) reveal that as the solvent becomes enriched in acetonitrile, the fraction of molecules existing as highly charged tautomer I decreases for CYS (0.68–0.40), PEN (0.85–0.34), and GSH (0.61–0.30). These results are related to the decreasing concentration of water as the solvent becomes enriched in acetonitrile.     

Chemistry of organic traces in air,XI: Sources and variations of volatile halocarbons in rural and urban air in Southern Germany

The variations of concentrations of volatile halocarbons (CHCl₃, CCl₄, CH₂Cl—CH₂Cl, CCl₃—CH₃, CHCl—CCl₂, and CCl₂=CCl₂) in rural and urban air are demonstrated by two series of air sampling carried out in Southern Germany. The interpretation of the changes in concentrations for the individual compounds is based on specific local input for the chlorinated solvents and on changing weather conditions during the sampling periods.Dedicated to Professor J. F. K. Huber on the occasion of his 65th birthday     

Phenolic-iodine Redox Products: Mass Spectrometry,Thermal and Other Physico-chemical Methods of Analyses

Three interesting new compounds formed as a result of phenols-iodine redox reactions were investigated by mass spectral fragmentation (MS) and thermal analyses (TA) as well as some other physicochemical methods as microanalysis and infra-red spectroscopy to elucidate their structures. The characterization of the compounds was satisfactorily achieved by using the above analytical tools and their proposed general formulae, were found to be C₂₄H₁₅O₈I (PC-IO ₃ ^– ), C₂₄H₁₄O₁₂ I₂ (PG-IO ₃ ^– ) and C₁₂H₈O₆I₂ (PG-IO ₄ ^– ).The fragmentation pathways of PC-IO ₃ ^– , PG-IO ₃ ^– and PG-IO ₄ ^– have been examined using electron ionization (EI) mass spectrometry in comparison with thermal analyses (TG and DTA). Both decomposition modes were investigated, and the fragmentation pathways were suggested. The combined application of mass spectrometry and thermogravimetry (MS and TG) in the analysis of the products allowed the characterization of the fragmentation pathway in MS.The major pathway in both techniques of PC-IO ₃ ^– is due to the loss of CHO followed by CH₃I+2H₂O. It is due to the loss of 2H₂O followed by the loss of 2CH₃I for PG-IO ₃ ^– . While for PG-IO ₃ ^– it is related to the loss of 2H₂O followed by loss of 2CH₃I molecule stepwise. Different stabilities for initial products and some fragments are discussed.This revised version was published online in November 2005 with corrections to the Cover Date.     

Measuring Contact Angles at Copper Electrodes

Potential dependences of the angle of contact between perfluorodecaline C₁₀F₁₈ and copper, copper(I) sulfide, and copper telluride Cu₄Te₃ in 0.1 M CH₃COONa are measured. The data are in good agreement with the metal hardness measured in 1 M KOH. The uncharged-surface potentials (USP) for copper, copper(I) sulfide, and copper telluride equal 0.05–0.07, –0.02 to –0.04, and 0.05–0.07 V (NHE) in 0.1 M CH₃COONa. Studying the effect of Br^– ions shows that USP for copper and Cu₂S shift in, respectively, the negative and positive directions with an increase in [Br^–]. For copper telluride, USP shifts in the positive direction at low Br^– concentrations, and at NaBr concentrations in excess of 0.04 M, in the negative direction.     

Volumetric properties of tetraphenylporphine,their metallo-complexes and some substituted tetraphenylporphines in benzene solution

Densities, apparent molar volumes and partial molar volumes of benzene solutions of tetraphenylporphine, H₂TPP, tetraphenylporphine metallo-complexes, MTPP (where M=Ni,Cu,Zn,Pd,Ag, and Cd), and some substituted tetraphenylporphines H₂T(i-R)PP (where i=2–4 and R=–Cl,–CH₃,–OCH₃) H₂T(i-F)PP (where i-2,3), H₂T(3-Br)PP, and H₂T(3-I)PP were determined at 25°C. It was found that the partial molar volumes of the studied compounds correlate linearly with the first ionization potential of the corresponding metal atom. The calculated values of the surface and volume accessible to the solvent, and the solvent-excluded volume for different conformations of H₂TPP, were compared with experimental data. The volume per molecule for different crystalline forms of H₂TPP and MTPP were compared with the partial molar volumes of the corresponding compounds in benzene solutions. The correlation between the partial molar volumes of H₂T(3-R)PP and their Van der Waals volumes are presented for R=–H, –F,–CH₃,–Cl,–Br,–OCH₃, and –I. The experimental data are rationalized in terms of differences in the conformational states of the molecules.     

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.     

Molecular,thermodynamic, and kinetic parameters of iodomethanes and iodomethyl radicals: <Emphasis Type="Italic">ab initio</Emphasis> calculations

The wave functions and enthalpies of formation of the ground states of iodomethanes CH_{4– x} I_x and iodomethyl radicals CH_3–x I_x. (x = 1–3) were calculated ab initio with regard to electron correlation. The geometries of the molecules of these compounds were determined, as well as the normal mode frequencies and other parameters, which were used for calculating the thermodynamic functions in the 0–1500 K range. These functions were used for calculating the constants of the CH_4–x I_x CH_4–x I _x–1 + I and CH_4–x I_x + I CH_{4– x} I _x–1 + I₂ equilibria, which, in turn, were used for calculating the corresponding rate constants in the high concentration limit.Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 11, 2004, pp. 1812–1822.Original Russian Text Copyright © 2004 by Dymov, Skorobogatov, Tschuikow-Roux.This revised version was published online in April 2005 with a corrected cover date.     

Organotin speciation in aquatic matrices by CGC/FPD, ECD and MS, and LC/MS

Summary The sensitivity and reproducibility of CGC coupled to selective detectors for the determination of alkyl and aryltin compounds (R_xSnY_z, where R=C₄H₉ or C₆H₅, and Y=CH₃ or Cl) (x+z=4) have been evaluated. In this regard, single or dual flame FPD configurations, with or without interference filter (600 nm) have been compared. The electron impact (EI) selected ion monitoring detection (SIM) CGC-MS was also considered for confirmation of the FPD assignments as well as for quantitative purposes. Alternatively, the accuracy and sensitivity of the direct analysis of organotin chlorides (Y=Cl) by cold on-column injection CGC-ECD or by thermospray LC-MS were determined. According to this, an analytical protocol based on acid digestion, extraction with organic solvents modified with tropolone, derivatization with CH₃MgCl, cleanup with alumina and CGC-FPD analysis has been successfully applied to the characterization of organotin compounds in seawater, sediments and biota. The relative detection limits of the whole procedure were dependent of the tin species and the environmental compartment considered, ranging from 0.5 to 6.5 ng l^–1 for seawater, in the filterless operation mode, and 0.1–2 ng g^–1 and 0.7–8 ng g^–1 for sediments and biota, respectively, using a 600 nm interference filter. Reproducibility was in the range of 15% RSD. Aryl and hydroxyalkyltin were identified for the first time in the aquatic compartments.     

Trace detection of ambient brominated compounds by laser-induced photofragmentation/fragment detection spectrometry

Studies have been performed to evaluate the analytical capabilities of a novel, one color, laser-induced photofragmentation/fragment detection technique for the detection of ambient brominated compounds. Laser radiation at 260.634 nm is used to both fragment the brominated compounds and excite the characteristic Br atom photofragment via its two-photon 4p⁴5p⁴D⁰ ← 4p⁵ 2P^o transition. Detection is accomplished by either (2 + 1) resonance-enhanced multiphoton ionization (REMPI), or by laser-induced fluorescence (LIF) or stimulated emission (SE) from the 4p⁴5p⁴D⁰ → 4p⁴51s⁴P _, transitions at 844 and 751 nm, respectively. The SE signal is coaxial to the laser beam and is approximately two orders of magnitude greater than the LIF signal at 844 nm. Measurements are performed in a photolysis cell at total pressures of 1–760 Torr. For REMPI detection, total (nonselective) ion collection is employed using a miniature pair of electrodes. The absorption cross section of the two-photon 4p⁴5p⁴D° ← 4p⁵²P⁰ transition is estimated to be 1.8 × 10⁻⁴⁵cm⁴s and limits of detection in the ppb are obtained for CH₃Br, CHBr₃, and CHClBr₂.     

Elucidation of biochemical formation of C1/C2-(bromo-/chloro)-hydrocarbons

Summary To elucidate possible biochemical pathways of the formation of halogenated C₁/C₂-hydrocarbons we investigated the product pattern of the reaction of chloroperoxidase (CPO) with natural substances including the haloform reaction as a second step. The analysis of the reaction products was performed by HRGC-ECD. We report here first results. As substrates we used acetic acid and acetone while KBr and NaCl served as halogen sources. The system acetic acid/KBr/CPO formed tribromomethane as the main product, with dibromochloromethane (CHBr₂Cl) and 1,1,2,2-tetrachloroethane as by-products. Incubation with acetone resulted in the formation of CHBr₃ as the main product, with CHBr₂Cl, CH₂Br-CH₂Br, CHCl₂-CHCl₂, CHCl₂-CCl₃ and trichloroethene as side products, while the reaction of acetone with NaCl and CPO yielded chloroform as a main product.Results partly presented at the ANAKON '91 in Baden-Baden, April 22–24, 1991     

Reactions of organylhalosilanes with 1,1,3,3-tetra- and hexamethyldisilazane

Organylchlorosilanes, and also SiCl₄, decompose 1,1,3,3-tetra- and hexamethyl-disilazanes with formation of hitherto unknown organylchlorosilazanes of general formulas R_4–nSiCl_n–1NHSiH(CH₃)₂ and R_4–nSiCl_n–1NHSi(CH₃)₃ (n=2–4) in yields of 54–98%. The IR and mass spectra of the prepared compounds were studied.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1159–1162, May, 1991.     

Synthesis of Silver Complexes in DMSO–HX and DMSO–HX–Ketone Systems

Comparative analysis of the oxidizing and complexing properties of the DMSO–HX (X = Cl, Br, I) and DMSO–HX–ketone (X = Br, I; the ketone is acetone, acetylacetone, or acetophenone) systems toward silver was performed. The reaction products are AgX (X = Cl, Br, I), [Me₃S⁺]Ag _n X^– _m (n= 1, 2; m= 2, 3; X = Br, I) and [Me₂S⁺CH₂COR]AgX^– ₂(R = Me, Ph; X = Br, I). The composition of the obtained complexes depends on both the DMSO : HX ratio and the nature of HX, as well as on the methods used to isolate solid products from the solution. It was noted that the formation of the [Me₂S⁺CH₂COMe]AgBr^– ₂complex in the Ag⁰–DMSO–HBr–acetylacetone system occurs with cleavage of the acetylacetone C–C bond and follows a specific reaction course. The optimum conditions for production of the silver compounds in the title systems are determined.     

Determination of volatile halogenated hydrocarbons in tap water,seawater and industrial effluents by glass capillary gas chromatography and electron capture detection

A rapid and sensitive method to determine volatile organohalides in different types of waters has been developed. The chromatographic system is based on the resolving power of the glass capillary column and the high sensitivity of the electron capture detector. The capillary columns were connected to the detector so that the eluate from the column is mixed with thermostatted purge gas to minimize band broadening due to dead volumes. The low column bleeding and decreased band spreading from capillary columns enhance the sensitivity to very low levels: 1 fg (10^?15g) for carbon tetrachloride, despite dilution of the column eluate by the purge gas. The water samples of 100 ml were extracted with 1 to 10 ml n-pentane which is the most practical alkane with respect to purity. When using high water to pentane ratios corrections had to be made, due to low extraction yield, to get accurate quantifications. A column with Carbowax 400 stationary phase permits direct tap water injection. The water peak concealed the substances eluated after CHCl₃ and CHBrCl₂. The gas chromatographic separation of haloforms in tap water could be shortened to 30 seconds using a 10 m SE–52 column with an increased film thickness. Besides tap water and seawater, industrial waste water from a pulp mill was analyzed. Ten different halogenated organic compounds, ranging from 1 ng/I to 760 μg/I, were quantified in the different waters. Bromoform, which had not previously been found in seawater, was detected. Chromatogram of a standard mixture containing 11 organohalides. Stationary phase, SE-52; 33 m × 0.3 mm i.d. inj. temp. 200°, column temp. 50°, interface 250°, detector temp. 250°. Helium carrier gas flow rate, 36 cm/s, scavenger'gas flow 30 ml/min. Split ratio 1:20, 1 = CH₂CI₂, 2 = CHC1₃, 3 = CH₃CC1₃, 4 = CC1₄, 5 = CHCICCI₂, 6 = CHBrCI₂, 7 = CBrC1₃, 8 = CHBr₂Cl, 9 = CCl₂CC1₂, 10 = CHCl₂l, 11 = CHBr₃.     

Tin(IV) complexes ofSchiff bases derived from salicylaldehyde and aminoalcohols

11 and 12 molar reactions of tin(IV) chloride with theSchiff bases, HO–C₆H₄CHNROH [where R=–(CH₂)₂–, –CH₂–, –CH(CH₃)–, –(CH₂)₃–, and –CH(C₂H₅)CH₂–] have been studied in different stoichiometric ratios and derivatives of the type SnCl₄(SBH₂) and SnCl₄(SBH₂)₂ (whereSBH₂ represents theSchiff base molecule) have been isolated. These have been characterised by elemental analysis, conductivity measurements and I.R. spectral studies.