Development of a KI Annular Denuder for NO2 Collection

Abstract

The use of a KI-coated annular denuder for eliminating NO₂ interference during sampling of airborne particulate matter on filter media is proposed. The performances of this novel diffusion sampler were evaluated in a series of practical tests concerning optimization of the sorption efficiency of NO₂. Results pointed out that a properly sized annular denuder under 1 m long could be able to remove HO₂ before collecting aerosols at laminar airflows as high as 15 1 min^?1.     

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.     

Preparation and X-Ray Structure of Cubane-Type Mixed Metal Aqua Ion, [Mo3NiS4(H2O)10]4+

Abstract

We have recently reported that the incomplete cubane-type aqua ion, [Mo₃S₄(H₂O)₉]⁴⁺ (A), reacts with metals (Fe,¹ Cu,², and Hg³) to give cubane-type mixed metal aqua ions, the core structures of which have been verified by the X-ray structure analyses of the complexes derived from the aqua ions. In addition, it was found that the reaction of A with metallic magnesium gave a double cubane-type aqua ion.⁴ We now present the preparation, properties, and X-ray structure of a new cubane-type molybdenum-nickel-sulfur mixed metal cluster compound, [Mo₃NiS₄(H₂O)₁₀](CH₃°C₆H₄·SO₃)₄·6H₂O (B), prepared from the aqua ion A and metallic nickel. Mo₂Ni₂Cp₂(CO)₂ is the only compound so far reported to have the cubane-type Mo-Ni-S core.⁵     

Use Of Diffusion Controlled Preconcentration Systems With Chemically Immobilized Coatings For The Determination Of Atmospheric Nitric Acid

Abstract

A new coating procedure for different diffusion controlled preconcentration methods (tubular denuder, annular denuder, diffusion screen) is described for the determination of nitric acid in air. In this study, a silanization reaction is applied to obtain a chemically fixed coating with an end placed functional NH₂-group, which can be used as a sink to collect acidic compounds from air. This coating must be carried out only once and can be used for a long time. The denuders, coated with this procedures, were compared with conventionally coated NaF denuders.     

Ab initio study of the potential energy surface and product branching ratios for the reaction of O(D) with CH3CH2F

The potential energy surface of O(¹D) + CH₃CH₂F reaction has been studied using QCISD(T)/6-311++G(d,p)//MP2/6-311G(d,p) method. The calculations reveal an insertion–elimination reaction mechanism of the title reaction. The insertion process has two possibilities: one is the O(¹D) atom inserting into C–F bond of CH₃CH₂F produces one energy-rich intermediate CH₃CH₂OF and another is the O(¹D) atom inserting into one of the C–H bonds of CH₃CH₂F produces two energy-rich intermediates, IM1 and IM2. The three intermediates subsequently decompose to various products. The calculations of the branching ratios of various products formed though the three intermediates have been carried out using RRKM theory at the collision energies of 0, 5, 10, 15, 20, 25 and 30 kcal/mol. CH₃CH₂O is the main decomposition product of CH₃CH₂OF. HF and CH₃ are the main decomposition products for IM1; CH₂OH is the main decomposition product for IM2. Since IM1 is more stable and more likely to form than CH₃CH₂OF and IM2, HF and CH₃ are probably the main products of the O(¹D) + CH₃CH₂F reaction. Our computational results can give insight to reaction mechanism and provide probable explanations for future experiments.     

Annular diffusion denuder for simultaneous removal of gaseous organic compounds and air oxidants during sampling of carbonaceous aerosols

A specially designed annular diffusion denuder for simultaneous removal of organic gaseous compounds and atmospheric oxidants in carbonaceous aerosol sampling is presented. Various kinds of denuder coatings were compared with respect to the collection efficiency of both organic gaseous compounds and NO₂ and ozone. The optimum sorbent is a mixture of activated charcoal and sulfite on molecular sieve. To ensure high collection efficiency over long-term field operation, two annular diffusion denuders are combined in series. The first half of the first denuder is filled with Na₂SO₃ on molecular sieve (23 cm long layer) while the second half of the first denuder and the whole second denuder are filled with activated charcoal (the total length of the charcoal section is 67 cm).     

VIBRATIONAL SPECTRA AND STRUCTURE OF ALKOXY AND CHLOROALKOXY DERIVATIVES OF ANTIMONY(V)

Abstract

Vibrational spectra of (CH₃O) _n SbCl_5–n . n = 1: 1; n = 2: 2: n = 3: 3: n = 4: 4; n = 5: 5; have been recorded. According to ir and Raman data 1–5 are centrosymmetrical bridged dimers. The Raman spectra of 3–5 exhibit v(Sb–O) doublets of terminal CH₃O at 530–541 and 550–570 cm^?1; vibrations of the 4-membered Sb₂O₂ ring, observed in the 500–517 cm^?1 region of the ir spectra of 1–5, are absent. The v(C–O) bands of bridged and terminal CH₃O are shifted to higher wave numbers (60 and 31 cm^?1, respectively) in the series 1 → 5. The stability of the dimers increases in the series 1 < 2 < 3 < 4 ? 5. At 100–120°C and in CH₃CN solutions dimers of 1–3 dissociate to monomers (v(Sb–O) 537–540 cm^?1, ir data). The monochloride, 4, is partially dissociated in CH₃CN. On solution of the tetrachloride, 1, in benzene a dimer-monomer equilibrium has been observed, with the dimeric form being predominant.     

Synthesis,crystal structures and NIR luminescence of sandwich-like tetradentate salophen phenoxo-bridged heterotrinuclear metal complexes

Six phenoxo-bridged tetradentate salophen heterotrinuclear Zn₂Ln complexes, [Ln(ZnL)₂(NO₃)₃(CH₃OH)₂]·CH₃OH·CH₂Cl₂ [Ln?=?Pr (1), Nd (2)] and [Ln(ZnL)₂(NO₃)₃(CH₃OH)]·CH₃OH·CH₂Cl₂ [Ln?=?Eu (3), Ho (4), Er (5), and Yb (6)], have been isolated from reactions of N,N′-bis(salicylidene)-1,2-(phenylene-diamine) with Ln(NO₃)₃6H₂O and Zn(OAc)₂2H₂O. X-ray diffraction analysis reveals that 1–6 are isomorphic with phenoxo-bridged, sandwich-like {Zn₂Ln} core. Near infrared (NIR) luminescence spectra show that 6 exhibits typical emission of Yb³⁺ upon excitation at the ligand-centered absorption band at 357?nm.     

“Instant Methylide” Modification of the Corey–Chaykovsky Epoxide Synthesis

Abstract

We report that Me₃S(O)⁺I^? (1) and Me₃S⁺I^? (2) form stable, dry mixtures with KOt-Bu and NaH, respectively, which remain stable upon prolonged storage (>1 year). The corresponding methylides (Me₂SO=CH₂ and Me₂S=CH₂) are generated upon addition of DMSO or DMSO/THF solutions of carbonyl compounds, cleanly affording epoxides via the Corey–Chaykovsky reaction in good yields and short reaction times (as short as 20 min when 1–2 mmol of various ketones and aldehydes were treated with a mixture of 1 and KOt-Bu at 50–60°C).     

反式2-甲基-2-丁烯酸甲酯与臭氧反应机理的计算研究

采用G3B3方法构建反式2-甲基-2-丁烯酸甲酯与O3反应体系以及后续Criegee自由基有、无水分子参与下异构化反应的势能面剖面.结果表明,反式2-甲基-2-丁烯酸甲酯与O3反应首先生成一个稳定的五元环中间体,此中间体按断键位置不同后续裂解反应存在两条路径,分别生成产物P1(CH3CHOO+CH3OC(O)C(CH3)O)和P2(CH3CHO+CH3OC(O)C(CH3)OO).利用经典过渡态理论(TST)并结合Wigner矫正模型计算了200-1200 K温度区间内标题反应的速率常数kTST/W.计算结果显示,294 K时,该反应速率常数为7.55×10-18cm3molecule-1s-1,与Bernard等对类似反应所测实验值非常接近.生成的Criegee自由基(CH3CHOO和CH3OC(O)C(CH3)OO)可分别与水分子发生α-加成及β-氢迁移反应,其中Criegee自由基与水的α-加成反应较其与水的β-氢迁移反应具有优势.另外与无水分子参与CH3CHOO和CH3OC(O)C(CH3)OO异构化反应相比,水分子的参与使得异构化反应较为容易进行.     

Determination of Spin-Spin Coupling Constants J(PP) on the Basis of 13C and 31p NMR Data

Abstract

The diphosphine dioxides Ph₂P (O) CH₂P (O)Ph₂.(I, Ph₂P(O)CH₂CH₂P(O)Ph₂ (II), Ph₂P(O)CH=CHP(O)Ph₂-cis (III), -trans (IV), [Ph₂P(O)] C=CH (V), [Ph₂P(O) 1₂C=PPh₃ (VI), and also non-symmetric Ph₂(P)OCH=CHP(O)PhEt-trans (VII), Et²P(O)CH=CHP(O)PhEt-trans (VIII), have been studied in CH²C1₂ and CHCl₃ solutions by means of ¹³C and ³¹P NMR.     

Vertical proton affinities of CH2O and CH2OH+ in their ground singlet,excited triplet and ionized doublet states

Vertical proton affinities were calculated with closed and open shell direct SCF-MO methods for the ground, excited triplet and ionized doublet states of CH₂O and CH₂OH⁺.The computed gas phase basicity of CH₂O follows the order: CH₂O(¹ A ₁) > CH₂O*(³ A ₁ or ³ A ₂) > CH₂O⁺(² B ₂ or ² B ₁).     

Synthesis,Characterization, and Structures of α-Substituted Selenenyl-Acetophenones

Abstract

A series of α-substituted selenenyl acetophenone derivatives of the types, [PhC(OCH₂CH₂O)CH₂Se]₂, [PhC(OCH₂CH₂O)CH₂SeR], (PhCOCH₂Se)_2, and [PhCOCH₂SeR] have been prepared. These compounds have been characterized by elemental analyses, IR and NMR (¹H, ¹³C, ⁷⁷Se) spectroscopy. The compounds, [PhC(OCH₂CH₂)CH₂Se]₂ and (PhCOCH₂Se)₂ have been structurally characterized by single crystal X-ray diffraction analyses. The former shows intra-molecular Se‐?‐?‐O interaction, while the latter exhibits inter-molecular nonbonding Se‐?‐?‐O interaction.

[Supplementary materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements for the following free supplemental files: Additional text and figures.]     

Tin Tetrachloride Adducts with Arylphosphoramidates: A Multinuclear (31P, 19F,and 119Sn) NMR Characterization in Solution

Abstract

The synthesis of octahedral complexes [SnCl₄L₂] (L = R₂NP(O)(OCH₂CF₃)(O-p-tolyl): R₂N = Me₂N (1), Et₂N (2), CH₂(CH₂CH₂)₂N (3), and O(CH₂CH₂)₂N (4), or L = R₂NP(O)(OCH₂CF₃)(O-p-PhNO₂): R₂N = Me₂N (5), Et₂N (6), and O(CH₂CH₂)₂N (7) is described. The new adducts have been characterized by multinuclear (³¹P, ¹⁹F, ¹¹⁹Sn) NMR, IR spectroscopy, and elemental analyses. The solution NMR data show the presence of a mixture of cis and trans isomers. The structure of the complexes in solution was further confirmed by ¹¹⁹Sn NMR spectra, which display a triplet for each isomer, indicating an octahedrally coordinated tin center. The effects of the nature of R and Ar substituents on the donor ability of the P=O group in the ligands R₂NP(O)(OCH₂CF₃)(OAr) were investigated on the basis of ¹¹⁹Sn NMR chemical shifts and used to classify these ligands according to their Lewis basicity.     

Feinreinigung von Radiostrontiumproben mittels Ionen-Chromatographie

Summary An annular denuder system for simultaneous determination of gaseous and particulate pollutants in ambient air was developed. Inorganic acids (HCl, HNO₃) were collected in a NaF-coated denuder, while organic acids (HCOOH, CH₃COOH) were trapped in one coated with KOH. NH₃ was sampled with a H₃PO₄-coated denuder tube. Particulate H₂SO₄ was evaporated at elevated temperature (145°–155°C) and deposited on a NaF-coating together with HCl and HNO₃ originating from thermal decomposition of NH₄Cl and NH₄NO₃. NH₃ resulting from deammoniation of (NH₄)₂SO₄ as well as NH₃ remaining from NH₄Cl and NH₄NO₃ were collected in a H₃PO₄-coated denuder. The practical collection capacity of the tubes ranged from 0.35 to 1.0 mol calculated from an experimentally determined sorption efficiency of at least 90%. The precision, expressed as relative standard deviation, of sampling and analytical procedures was determined from duplicate measurements in ambient air. The reproducibility varied from 9% to 14% for the gaseous components, while that of the particulate compounds ranged from 12% to 23%. Aqueous extracts of the denuder coatings were analysed for ionic components by ion chromatography using conductivity detection. The minimum detectable concentration in air was found to be 1.5 to 14 nmol/m³ for the different compounds calculated for 1.6 m³ sample volume, based on 3-h measurements at a flow of 9 l/min.

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Bestimmung der atmosphärischen Konzentrationen von anorganischen und organischen gasförmigen Säuren, NH₃, teilchenförmigem SO ₄ ^2– , NO ₃ ^2– und Cl^– mit einem Ringspaltrohr-Diffusionsdenudersystem

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On leave from the Institute of Occupational Health, Helsinki, Finland     

The reactions of non-gem-hexanedioxytetrachlorocyclotriphosphazene with 2-(2-hydroxyethyl)thiophene,benzyl alcohol and 1,1,3,3-tetramethylguanidine. Spectroscopic studies of the derived products

Abstract

Reactions of non-gem-hexanedioxytetrachlorocyclotriphosphazene (1) with monofunctional nucleophilic reagents, 2-(2-hydroxyethyl)thiophene (2), benzyl alcohol (3) and 1,1,3,3-tetramethylguanidine (4) were investigated. The reactions, using an excess of NaH, in THF solutions, under refluxing conditions and with 1:2?mole ratios allow the synthesis of the following novel cyclotriphosphazene derivatives: 2,4-dichloro-2,4-(hexane-1,6-dioxy)-6,6-[2-(2-ethoxy)hiophene]-cyclotriphosphazatriene, N₃P₃Cl₂[O(CH₂)₆O-(C₆H₈OS)₂] (5); 2,4-(hexane-1,6-dioxy)-2,4,6,6-[2-(2-ethoxy) thiophene]-cyclotriphosphazatriene, N₃P₃[O(CH₂)₆O-(C₆H₈OS)₄] (6); 2,4-dichloro-2,4-(hexane-1,6-dioxy)-6,6-(methoxybenzene)-cyclotriphosphazatriene, N₃P₃Cl₂[O(CH₂)₆O-(C₆H₅CH₂O)₂] (7); 2,4-(hexane-1,6-dioxy)-2,4,6,6-(methoxybenzene)-cyclotriphosphazatriene, N₃P₃[O(CH₂)₆O-(C₆H₅CH₂O)₄] (8); and 2,4-dichloro-2,4-(hexane-1,6-dioxy)-6,6-(1,1,3,3-tetramethyguanidine)-cyclotriphosphazatriene, N₃P₃Cl₂[O(CH₂)₆O-HN-CN₂(CH₃)₄] (9). The structures of the synthesized compounds (5–9) have been characterized by elemental analysis, TLC-MS, ¹H, ¹³C and ³¹P {+¹H} and {?¹H} NMR spectral data.     

Syntheses,crystal structures,and magnetic properties of a series of Fe2Ln complexes

A family of phenoxo-bridged heterometallic Schiff base trinuclear complexes, [Fe₂LnL₂(C₃H₇COO)(H₂O)]·CH₃OH·CH₃CN·H₂O (Ln = Sm, 1; Gd, 2; Tb, 3; Dy, 4) is reported. Those complexes were afforded by “one-pot” reaction of a polydentate Schiff base ligand 2-hydroxy-3-methoxy-phenylsalicylaldimine (H₂L) with Fe(NO₃)₃·9H₂O, Ln(NO₃)₃·6H₂O and sodium butyrate (C₃H₇COONa) in a mixture of methanol and acetonitrile in the presence of triethylamine as a base. Single-crystal X-ray diffraction analysis reveals that the structures of the four complexes are isomorphic. In each complex, two anionic [FeL₂]^? units coordinate to the central lanthanide ion as a tetradentate ligand using its four phenoxo oxygens, forming a two-blade propeller-like molecular shape. Magnetic properties of 1–4 were investigated using variable temperature magnetic susceptibility, and weak ferromagnetic exchange between the Fe^III and Ln^III ions has been established for the Gd derivative. The Tb and Dy complexes show no evidence of slow relaxation behavior above 2.0 K.     

Self-assembled tetrameric H2O clusters in the crystal lattice of [Cu(μ2-OH){Ph2P(O)NP(O)Ph2-κ1O,O′}(1,10-phen-κ2N,N′)]2·2H2O

Abstract

The synthesis and characterization of the dinuclear Cu(II) complex [Cu(μ²-OH){Ph₂P(O)NP(O)Ph₂-κ¹O,O′}(1,10-phen-κ²N,N′)]₂·2H₂O (1), 1,10-phen?=?1,10-phenanthroline, is described. X-ray crystallographic studies reveal that the Cu(II) centers of 1 are bridged by two OH^? groups and are coordinated by the (O,O)?= Ph₂P(O)NP(O)Ph₂^? ligand in a monodentate fashion, unprecedented for Cu(II). The crystal lattice of 1 also contains H₂O molecules, which are involved in the formation of a hydrogen bonding network with bridging OH^? groups and noncoordinated O atoms of the (O,O) ligand. These H₂O molecules are arranged in the crystal lattice of 1 as tetrameric clusters. The packing of molecules in the structure of 1 was investigated by Hirshfeld Surface analysis.     

Glycol modified cis -diisopropoxy- bis ( N -phenylsalicylideneiminato)zirconium(IV): syntheses,characterization and low temperature transformation to nanocrystalline zirconia

Zr(OPrⁱ)₄·PrⁱOH reacts with N-phenylsalicylideneimine in anhydrous benzene in 1 : 2 molar ratio to afford [Zr{O(C₆H₄)CH=NPh}₂{OPrⁱ}₂] (1). Further reactions of 1 with various glycols yield heteroleptic complexes of the type [Zr{O(C₆H₄)CH=NPh}₂{O–G–O}] [where–G–= (CH₂)₂ (2), (CH₂CHCH₃) (3), (CH₃CHCHCH₃) (4), (CH₂CHC₂H₅) (5), (CH₂)₃ (6), (CH₂CH₂CHCH₃) (7), and (CH₂)₆ (8)]. All new derivatives have been characterized by elemental analyses, FTIR and NMR (¹H and ¹³C{¹H}) studies. FAB mass spectra of 1 and 7 revealed the monomeric nature of these complexes. Complete hydrolyses and low temperature transformations of 1 and 7 using Sol-Gel technique formed tetragonal phase of ZrO₂ at 700°C, whereas transformation of tetragonal to monoclinic phase occurred at 900°C. SEM observations of these samples indicate formation of agglomerates of nanocrystalline zirconia (Scherer analysis).     

A Novel Three-Dimensional Network Isophthalato-Bridged Lanthanide Complex: {Ln[C6H4(COO−)2-1,3](CH3COO−)(H2O)2}·H2O

The three-dimensional network of lanthanide (III) complexes with isophthalato (IPT) ligand, (Eu[C₆H₄(COO^?)₂-1,3](CH₃COO^?)(H₂O)₂}·H₂O 1 and {Sm[C₆H₄(COO^?)₂-1,3](CH₃COO^?) (H₂O)₂} H₂O 2, has been prepared by the hydro(solvo)thermal reaction of Eu(C1O₄)₃·6H₂O or Sm(C1O₄)₃·6H₂O, 1,3-dicyanobenzene and acetic acid in the presence of ethanol and H₂O. In the reaction, 1,3-dicyanobenzene was hydrolyzed to give IPT ligand. Single crystal x-ray analysis revealed that crystals 1 and 2 are isomorphous with the isostructural {M[C₆H₄(COO^?)₂-1,3](CH₃COO^?)(H₂O)₂}·H₂O unit. In 1 and 2, IPT acts as a bridging ligand to connect three adjacent metal atoms, forming a network like an undulating sheet paralleling the bc plane. The carboxylate from acetate bridges two adjacent metal atoms in a tridentate mode between the different sheets to extend the structure into a three-dimensional network.