The oxidation of thiosulphate ions by octacyanotungstate(V) in weak acidic medium

The kinetics of the oxidation of thiosulphate ions by octacyanotungstate(V) ions has been studied in the pH range 3.9–5.0. The reaction showed zero-order kinetics with respect to [W(CN)₈^3?] and is consistent with the rate law R = k[H⁺][S₂O₃^2?]². A reaction mechanism is proposed for the reaction with a third-order rate constant of 0.26 M^?2 s^?1 at 25°C.     

Formation and thermodynamic properties of mixed complexes of Cd(II) with thiourea and nitrite or thiosulphate ions as ligands

Formation and thermodynamic parameters of mononuclear mixed complexes Cd(SCN₂H₄)_n(NO₂)^2?p_p and Cd(SCN₂H₄)_n(S₂O₃)^2(1?p_p in aqueous solution were investigated by potentiometric measurements at different temperatures and μ = 1 for KNO₃.     

The reaction of pentaborane(9) with sodium cyanide and sodium cyanotrihydroborate

The reaction of pentaborane(9) with NaCN occurs in a 1:1 molar ratio at temperatures between ? 30° and + 10°C to yield the complex Na[B₅H₉CN], which can be isolated in the form of a dioxanate. When excess pentaborane(9) is used the reaction is relatively clean and yields predominantly the [B₉H₁₄]^? ion. With NaBH ₃CN no intermediates of the type Na[B₅H₉CN] are detected, and the major product is the [B₉H₁₄]^? ion, but no hydrogen is evolved in the reaction. Structures for the intermediate anions are suggested. No monocarbon carbaboranes were detected in any of the reactions.     

The reaction of lithiun aluminium hydride with carbon dioxide or sodium bicarbonate

The reaction of LiA1H₄ with CO₂ or NaHCO₃ at elevated temperatures has been investigated. Methane and ethylene are the primary products of each reaction. These molecules are probably the “explosive” reaction products formed when CO₂ fire extinguishers are used on LiAlH₄ fires.     

Synthesis and characterization of new complexes between sodium monoalkyl benzeneazophosphonates and dibenzo-18-crown-6

A new series of crystalline complexes of sodium monoethyl ester and sodium monobutyl ester of [α-(4-benzeneazoanilino)-N-benzyl]phosphonic acid,     

Micellization and intermicellar interactions in aqueous sodium dodecyl benzene sulfonate solutions

Quasielastic light scattering was used to investigate the size and shape of sodium dodecyl benzene sulfonate (SDBS) micelles in aqueous solutions. Measurements were made as a function of temperature and NaCl and SDBS concentrations. Light scattering data indicate that the micelles are spherocylinders with a semiminor axis of 22 Å. The length of the micelles increases strongly with salt concentration and decreases with temperature. The minimum micelle has an aggregation number of n⁰ = 28 and a hydrodynamic radius of R = 22 Å. Diffusion coefficient and intensity data were analyzed using a thermodynamic theory of micellar aggregation and a model based on DLVO theory of interactions.     

The solubility of uranium(IV) hydrous oxide in sodium hydroxide solutions under reducing conditions

The solubility of hydrous UO₂ in sodium hydroxide solutions containing sodium dithionite and/or Zn metal powder as reductants has been measured. The results provide no firm evidence for any amphoteric behavior of U(IV) but do set an upper limit of K ≤ 2 x 10^?23 for the hypothetical reaction:

The results provide no evidence for such a reaction.     

A study of some reactions of acetylacetonatobis(ethylenediamine)cobalt(III) ion in sodium hydroxide solution

The reactions of acetylacetonato cobalt (III) ion in sodium hydroxide solutions have been studied spectrophotometrically over a range of temperatures and hydroxide ion concentrations. The activation enthalpy, ΔH^≠ was 70.6 kJ mol^?1 and the activation entropy, ΔS^≠ was ? 119 JK^?1mol^?1, with a rate law of k_obs = k₂ [OH^?]². A mechanism involving initial de-chelation of the acetylacetone ligand is suggested. The rate of exchange of methyl hydrogen of the acetylacetone ligand was studied, using proton nuclear magnetic resonance. The rate law was k_obs = k [OH^?]. Initial de-chelation is also suggested as a mechanism for this process. The ¹³C nuclear magnetic resonance spectrum of the complex is reported.     

Raman study of halogen exchange equilibria in low melting mixtures consisting of sodium tetrachloroaluminate and tetrabromoaluminate

The halogen-redistribution reactions between [AlCl₄]^? and [AlBr₄]^? in molten mixtures of NaAlCl₄ and NaAlBr₄ with widely varying mole ratios have been studied by Raman spectroscopy at 160–300°C and the melting points have been measured. By monitoring the intensities of the totally symmetric stretching a₁-modes of both the parent tetrahalides as well as those of the mixed halides [AlCl₃Br]^?, [AlCl₂Br]^? and [AlClBr₃]^? it is concluded that the mixtures equilibrate very fast and consist of an almost random distribution of the five species. NaAlCl₄ and NaAlBr₄ form an eutectic mixture with a molar ratio near to 4:1, with a melting point of ca 142°C.     

Absorption and emission spectroscopy and magnetic susceptibility of sodium β-alumina doped with Mn,Co, and Ni

The absorption spectrum and magnetic susceptibility vs temperature have been measured for β-alumina doped with Mn, Co, and Ni. In addition, the emission spectra of Mn-doped samples have been measured. Mn and Co are shown to occupy tetrahedral sites and to be in the +2 oxidation state in β-alumina, in agreement with the results of previous investigators. Nickel is shown to occupy both octahedral and tetrahedral sites in β-alumina. Evidence indicates that nickel on octahedral sites is in the +3 oxidation state while that occupying tetrahedral symmetry sites is in the +2 oxidation state. The bands in the absorption spectrum for each metal are assigned and Dq, B, and C are calculated where possible.     

The isolation and x-ray crystal structure of a complex between sodium hexafluorophosphate and dibenzo-36-crown-12

The crystal structure of 2NaPF₆·dibenzo-36-crown-12 was determined by X-ray diffraction methods. The 2:1 (metal:ligand) complex crystallises in the monoclinic system, space group P2₁/n with cell constants of a = 14.189(2), b = 9.372(1), c = 16.750(3) Å, and β = 108.98(1)°. The two NaPF₆ units are each coordinated through five oxygen atoms to opposite faces of the macrocycle in a centrosymmetric manner.     

Investigations into the formation and characterization of microemulsions. I. Phase diagrams of the ternary system water—sodium alkyl benzene sulfonate—hexanol and the quaternary system water—xylene—sodium alkyl benzene sulfonate—hexanol

The phase diagrams of the ternary system water—sodium alkylbenzene sulfonate (NaDBS)-hexanol and the quaternary system water—xylene—NADBS—hexanol have been established at three different temperatures, namely 25, 37, and 50°C. The different phases formed have been qualitatively examined using optical (phase contrast and polarizing) microscopy. The textures of the various liquid crystalline phases in the ternary system have been identified, by comparison with previous studies in the literature. Some of the liquid crystalline phases have been quantitatively assessed using low angle X-ray diffraction. The latter measurements were also used to determine the unit cell dimensions in the various phases studied. With the quaternary system, particular attention was paid to the transparent region which consisted of an L₂ (inverse micellar) phase extending into another transparent region which has a blue “tinge” in some cases, namely the microemulsion (M) region. The amount of water solubilized in the L₂ (reverse micelle) or M + L₂ phase was calculated from the phase diagrams. With the ternary system the results showed a maximum in moles of water solubilized per mole total surfactant (NaDBS + hexanol) at a concentration of 0.3 mole surfactant, at an optimum molar ratio of n-hexanol to NaDBS of 4.5:1. This maximum was about twice with the quaternary system, when compared with that of the ternary system, indicating the importance of the role of xylene in solubilization of water by the surfactants. The present investigation has also shown that the extent of the microemulsion region is significantly reduced by increases of temperature when the NaDBS is lower than 15 wt%.     

The crystal structure of a sodium molybdenum oxide,Na6Mo10O33, containing cross-linked chains of octahedra and square pyramids

Na₆Mo₁₀O₃₃ crystallizes in the triclinic system with unit-cell dimensions a = 8.049(4), b = 12.180(6), c = 7.576(4) Å, α = 99.96(9), β = 100.74(1), γ = 109.88(10)°, and space group $\text{P}\text{1}$ with z = 1. The structure was solved using Patterson and Fourier methods. Of the 3045 unique reflections measured by counter techniques 2758 with I ≥ 3σ(I) were used in the least-squares refinement of the model to a conventional R of 0.030 (R_w = 0.034). The structure of Na₆Mo₁₀O₃₃ consists of two different types of chains of molybdenum-oxygen polyhedra linked to one another approximately at right angles. One chain of edge- and corner-shared distorted MoO₆ octahedra is approximately parallel to [001] and the second chain, consisting of corner-shared pairs of octahedra edge-shared to pairs of edge-shared MoO₅ square pyramids (inverted with respect to one another), is approximately parallel to [100]. These linked chains form an infinite three-dimensional network in the interstices of which the sodium atoms are located. One of the chains of the Na₆Mo₁₀O₃₃ structure is the same as that found in Ag₆Mo₁₀O₃₃; the second chain, however, does not occur in Ag₆Mo₁₀O₃₃.     

The effect of selfassociation of mercurated carbonyl compounds of mercury-199 chemical shifts

Temperature and concentration dependences of mercury-199 chemical shifts in benzene solutions of bis(methylethylketone)mercury Hg(CH₂COC₂H₅) (I) and α-bis(methylacetoacetone)mercury Hg(CH₂COCH₂COOCH₃)₂ (II) are determined by the ¹H-{¹⁹⁹Hg}method. The NMR data obtained and the IR spectra are indicative of selfassociation of I and II in solution with the formation of weak intermolecular coordination bonds Hg ← :OC. The enthalpies of complex formation calculated on the assumption of one mercury atom bonding with only one carbonyl function are equal to ?3.2 ± 0.1 kcal/mol and ?2.2 ± 0.1 kcal/mol for I and II, respectively.     

The formation of flouride complexes of titanium(IV)

The complex formation equilibria between titanium(IV) and fluoride ions have been studied at 25°C in 3 M(Na)Cl ionic medium by measuring, with an ion selective electrode for F^?, the free HF concentration in acid Ti(IV) solutions. The [H⁺] was kept within 0.25 and I M where the predominant form of uncomplexed metal is the dihydroxotitanium(IV) ion, Ti(OH)²⁺₂. The potentiometric data have been explained by assuming Ti(OH)₂F⁺, TiF₄ and HTiF^?₆, with equilibrium constants given in Table 3. Within the accuracy of the present e.m.f. study, ±0.2 mV, no evidence for intermediate complexes bearing 2, 3 and 5 F^? was found.From a special series of measurements, carried out by replacing a large part of the Cl^? with ClO^?₄, it is concluded that no appreciable amount of Ti(IV)Cl complexes is formed at the 3 M level employed as ionic medium.     

Structural study of a new hexagonal form of tungsten trioxide

A new form of tungsten trioxide WO₃ has been obtained by dehydration of $\text{WO}{}_3\text{·}\text{1}\text{3}\text{H}{}_2\text{O}$ hydrate. The structural study was carried out from X-ray powder diffraction and selected area electron diffraction data. The crystallographic characteristics are: the hexagonal system; a = 7.298(2) Å, c = 7.798(3) Å; Z = 6. This hexagonal WO₃ is built up of slightly distorted (WO₆) octahedra sharing their corners arranged in six-membered rings in layers normal to the hexagonal axis; stacking of such layers leads to formation of large hexagonal tunnels. Some confirmations of this structure were made by high-resolution electron microscopy. Powder X-ray diffraction allowed us to determine an average structure. Absence of suitable single crystals has not permitted us to perform a complete structural determination. Although the existence of such a hexagonal structure for pure WO₃ had been considered as likely, it had not been hitherto observed.     

Synthesis of silver (II) oxide by oxidation of silver or silver oxide by means of ozone

The oxidation by ozone of a suspension of silver or silver oxide in an aqueous solution of sodium hydroxide is described. It has been shown that the oxidation proceeds in two steps:Ag^O₃→Ag₂O^O₃→AgO.The experimental results are in good agreement with a mechanism of dissolution and precipitation. The silver (II) oxide obtained has remarkable properties of stability in alkaline solution and of reducibility to metallic silver. These special properties are probably due to the large size of the particles.     

Molar excess volumes of ternary mixtures of nonelectrolytes

Molar excess volumes V^E_ijk of methylenebromide i + pyridine j + β-picoline (k, cyclohexane (i) + pyridine (j) + β-picoline(K), benzene(i)+toluene(j)+1,2-dichloroethane(k), benzene(i) + 0-xylene(j) + 1,2-dichloroethane(k) and benzene(i) + p-xylene(j) + 1,2-dichloroethane(k) mixtures have been determined dilatometrically at 298.15 K. The data have been examined in terms of Sanchez and Lacombe theory and the graph-theoretical approach, and it is found that they are described well by the latter. Self- and cross-volume interaction coefficients V_jk, V_jjk and V_jkk, etc., have also been evaluated and the values utilised to study molecular interactions between the jth and kth molecular species in the presence of the ith in these i + j + k mixtures.     

Syntheses of N-silylformamidines by the hydrosilylation of carbodiimides

The hydrosilylation of carbodiimides was found to proceed at higher temperatures in the presence of catalytic amounts of palladium chloride or tris-(triphenylphosphine)chlororhodium to afford N-silylformamidines in high yield. These were found to be good precursors to formamidines and N-acetyl-formamidines.     

Degradation of aromatic compounds in ground-water, and methods of sample preservation

The degradation of acenaphthylene, acenaphthene, 2-methylnaphthalene, 2-methylindene, 3-methylindene and indene in water solutions was studied. These compounds at the 25-150 mug/l. level were almost totally degraded at ambient temperature within three days. The microbial population responsible for the degradation occurs naturally in ground-water taken from an aquifer in Ames, Iowa, which is contaminated with coal-tar products. These unidentified micro-organisms adapt readily to other waters when used as an inoculant for the degradation of aromatic compounds. The preservation of water to prevent such degradation was also investigated. Filtration through a 0.45-mum filter was found the most effective procedure for preserving the hydrocarbons in these waters.