1221564-02-8Relevant articles and documents
Multicomponent Cluster Ions. 2. Comparative Stabilities of Cationic and Anionic Hydrogen-Bonded Networks. Mixed Clusters of Water and Hydrogen Cyanide
Meot-Ner, (Mautner) Michael,Speller, Carlos V.
, p. 3663 - 3666 (1989)
The thermocemistry of cluster ions containing nH2O and mHCN molecules,for cluster up to rank r = n + m = 5, was obtained from equilibrium measurements.The clustering of H2O about H3O+ and OH- and the clustering of HCN about HCNH+ show distinct shell filling effects, but the clustering of H2O and HCN about CN- does not.Hydratation by one water molecule eliminates the difference of 5 kcal/mol between the proton affinities of HCN and H2O.Hydration also decreases the difference between the intrinsinc deprotonation energies, i.e., ΔH0acid, of H2O and HCN from 37.7 to 19.8 kcal/mol in the 4-fold hydrated species.In protonated clusters of a given rank r, exchange of H2O by HCN does not significantly affect the total stability of the cluster.This is in contrast to H2O/CH3OH and H2O/CH3CN protonated clusters and H2O/HCN anionic clusters, where increasing nonaqueous content is stabilizing.In the latter, the most stable clusters of any size are the neat CN-.nHCN clusters.
Thermal decomposition of hydrogen peroxide in the presence of sulfuric acid
Wu,Chen,Cheng,Lee,Shu
, p. 115 - 120 (2009/02/02)
Hydrogen peroxide (H2O2) is popularly employed as a reaction reagent in cleaning processes for the chemical industry and semiconductor plants. By using differential scanning calorimetry (DSC) and vent sizing package 2 (VSP2), this study focused on the thermal decomposition reaction of H2O2 mixed with sulfuric acid (H 2SO4) with low (0.1, 0.5 and 1.0 N), and high concentrations of 96 mass%, respectively. Thermokinetic data, such as exothermic onset temperature (T 0), heat of decomposition (ΔH d), pressure rise rate (dP/dt), and self-heating rate (dT/dt), were obtained and assessed by the DSC and VSP2 experiments. From the thermal decomposition reaction on various concentrations of H2SO4, the experimental data of T 0, ΔH, dP/dt, and dT/dt were obtained. Comparisons of the reactivity for H2O2 and H2O2 mixed with H2SO4 (lower and higher concentrations) were evaluated to corroborate the decomposition reaction in these systems.
Excited state dynamics of liquid water: Insight from the dissociation reaction following two-photon excitation
Elles, Christopher G.,Shkrob, Ilya A.,Crowell, Robert A.,Bradforth, Stephen E.
, p. 1 - 8 (2009/02/03)
The authors use transient absorption spectroscopy to monitor the ionization and dissociation products following two-photon excitation of pure liquid water. The primary decay mechanism changes from dissociation at an excitation energy of 8.3 eV to ionization at 12.4 eV. The two channels occur with similar yield for an excitation energy of 9.3 eV. For the lowest excitation energy, the transient absorption at 267 nm probes the geminate recombination kinetics of the H and OH fragments, providing a window on the dissociation dynamics. Modeling the OH geminate recombination indicates that the dissociating H atoms have enough kinetic energy to escape the solvent cage and one or two additional solvent shells. The average initial separation of H and OH fragments is 0.7±0.2 nm. Our observation suggests that the hydrogen bonding environment does not prevent direct dissociation of an O-H bond in the excited state. We discuss the implications of our measurement for the excited state dynamics of liquid water and explore the role of those dynamics in the ionization mechanism at low excitation energies.
Preferential oxidation of CO in H2 by aqueous polyoxometalates over metal catalysts
Kim, Won Bae,Voitl, Tobias,Rodriguez-Rivera, Gabriel J.,Evans, Steven T.,Dumesic, James A.
, p. 778 - 782 (2007/10/03)
Stream cleaning: CO in CO/H2 mixtures is oxidized preferentially at room temperature with an aqueous polyoxometalate (POM) solution over gold catalysts (see scheme). The rate of H2 oxidation is slow and is inhibited by CO. This process can be used to remove CO efficiently from H 2 gas streams. The solution containing protons and reduced POM can be used to produce electrical energy at a fuel-cell anode through re-oxidation of the reduced POM.
Kinetic study of the complex formation of boric and boronic acids with mono- and diprotonated ligands
Ito, Hideaki,Kono, Yoko,Machida, Akinori,Mitsumoto, Yoko,Omori, Kenji,Nakamura, Noriko,Kondo, Yuichi,Ishihara, Koji
, p. 28 - 36 (2008/10/08)
The complex formation reactions of boric and boronic acids (RB(OH)2: R=OH, n-Bu, Ph, and m-NO2Ph) with 4-isopropyltropolone (Hipt) and chromotropic acid (H2cht2-) have been studied kinetically at various pH. The reactions of H2ipt+ with boronic acids were faster than those of Hipt by a factor of 1.5-11, and fully deprotonated ipt- also reacted with m-NO2PhB(OH)2, but slower than Hipt. The tetrahedral m-NO2PhB(OH)3- ion did not react with Hipt. Reaction routes for the complexation of boric acid with chromotropic acid could not be specified because of the unexpected problem of proton ambiguity. Mechanism for the reactions of boronic acids with bidentate ligands was discussed in terms of rate determining chelate ring closure. It was concluded that at least one proton is necessary for the OH- in the tetrahedral intermediates to be eliminated smoothly as water, and a doubly hydrogen-bonded intermediate was proposed for the reactions with diprotic ligands.
Interaction of water with GeCl4, SnCl4, and AsCl 3
Efremov,Potolokov,Nikolashin,Fedorov
, p. 837 - 846 (2008/10/08)
The interaction of water with GeCl4, SnCl4, and AsCl3 was studied by IR spectroscopy. The results demonstrate that these chlorides contain molecular water in monomeric form. At water concentrations above 10-2 mol/l, GeCl4 also contains H3O+ ions. The mechanisms of GeCl4 and AsCl3 hydrolysis were studied over a wide range of water concentrations.
Kinetics of the reaction of O2+ with CH4 from 500 to 1400 K: A case for state specific chemistry
Dotan,Viggiano
, p. 6112 - 6118 (2007/10/03)
The temperature dependent rate constants and branching ratios for the reaction of O2+ with CH4 and O2 with CD4 from 500 to 1400 K were determined. By comparing to previous studies, the influence on vibrational excitation in the CH4 reactant was derived.
Orthorhombic B2CN crystal synthesized by high pressure and temperature
He,Tian,Yu,Wang,Liu,Guo,Li,Jia,Chen,Zou,Yanagisawa
, p. 431 - 436 (2008/10/08)
B0.54C0.28N0.18 precursor powder with turbostratic structure was prepared by using melamine and boric acid. The precursor was transformed into orthorhombic B2CN under definite high pressure and temperature conditions. The composition of the orthorhombic B2CN powder is B0.47C0.23N0.30. Its lattice parameters are a=0.4776 nm, b=0.4585 nm and c=0.3629 nm. A strong absorption band from 1088 to 1385cm-1 of orthorhombic B2CN was observed by infrared measurement. In the photoluminescence (PL) spectrum of orthorhombic B2CN powder measured at room temperature, a broad peak corresponding to its band-edge emission centers at 374 nm.
Temperature dependence of adlayers on Pt(1 1 1) and Au(1 1 1) in a sulfuric acid solution studied by in situ IRAS
Shingaya,Ito
, p. 425 - 430 (2008/10/08)
Temperature dependence studies of adsorption of sulfuric acid species on Pt(111) and Au(111) electrodes were carried out using in situ infrared reflection absorption spectroscopy. A temperature-dependent shift of the interconversion potential between HSO4-/H3O+ and H2SO4 on a Pt(111) electrode was observed. A temperature-dependent frequency shift of the absorption bands of HSO4- was also observed on both Pt(111) and Au(111) electrodes in the potential region where a √3×√7 structure evolved. Modelling experiments in ultrahigh vacuum revealed that ordering of the overlayer water molecules played an important role in the frequency of the absorption bands of HSO4-.
[Ru(II)(hedta)]- complexes of 2,2'-dipyridylamine (dpaH) and a bifunctional tethered analog, N,N,N',N'-tetrakis(2-pyridyl)adipamide (tpada)
Shepherd, Rex E.,Chen, Ya,Kortes, Richard A.,Ward, Matthew S.
, p. 30 - 39 (2008/10/08)
[Ru(II)(hedta)L]- complexes (hedta3- = N-hydroxyethylethylenediamine-N,N,N'-triacetate); L = dpaH (2,2'-dipyridylamine) and tpada (N,N,N',N'-tetrakis(2-pyridyl)adipamide)) have been studied by 1H NMR and electrochemical methods in aqueous solution. The bidentate rings of dpaH and tpada are differentiated as shown by NMR upon coordination to Ru(II) due to differences in the local environment. The dpa-R headgroup of each ligand binds 'in-plane' with the en backbone of hedta3- and with one pyridyl ring being nearer the amine of hedta3- having the pendant glycinato group (matching the known arrangement with bpy (2,2'-bipyridine)). Ru(II/III) E(1/2) values follow the order dpaH (0.32 V) a weaker π-acceptor ligand than bpy, and that the withdrawing carbonyl functionality enhances the π-acceptor capacity for the tpada ligand, approaching the stability imparted by bpy. Only the 1:1 [Ru(II)(hedta)(dpaH)]- complex forms even in the presence of excess dpaH. [Ru(II)(hedta)(dpaH)] has a pK(a) of the dipyridylamine proton of approximately 5.0 with [Ru(II)(hedta)(dpa-)] undergoing aquation (k(H2O)= 1.4 10-2 s-1) and OH--assisted dissociation (k(OH) = 1.33 104 M-1 s-1). The {[Ru(II)-(hedta)]2(tpada)}2- complex serves as a water-soluble model as to how {[ML']2(tpada)} complexes might act as an extended bridge between two metal binding sites, potentially those of metallo-derivatized DNA strands, or between one DNA strand and a protein crosslink. In this model M represents an appropriate metal for DNA derivatization such as Ru(II), Pt(II) or Pd(II) and L' represents the attachments to DNA nucleobase sites, aminocarboxylates/peptide coordination for antitumor purposes. (C) 2000 Elsevier Science S.A.
