über die Reaktionen von CH3OCl,CF3OCl,CF3OF und CF3OH mit dem supersauren System HF/MF5 (M = As,Sb) Darstellung und Charakterisierung von CH3OCl(H)+MF6− und CF3OCl(H)+MF6−

On the Reactions of CH₃OCl, CF₃OCl, CF₃OF, and CF₃OH with the Superacid System HF/MF₅ (M = As, Sb). Preparation and Characterization of CH₃OCl(H)⁺MF₆^? and CF₃OCl(H)⁺MF₆^? The preparation of the chlorine oxoniumsalts CH₃OCl(H)⁺MF₆^? and CF₃OCl(H)⁺MF₆^? by protonation of CH₃OCl and CF₃OCl in the superacid solution of HF/MF₅ (M = As, Sb) is described. However CF₃OF and CF₃OH have not been protonated under the same conditions. In the case of CF₃OH the formation of F₂CO · MF₅ is observed. The novel compounds are characterized by nmr- and vibrational spectroscopy.     

Facile synthesis of 3-substituted indoles containing highly polarized double bonds

In this paper, an effective procedure is described for the synthesis of novel indoles containing highly polarized double bonds. The strategy involves the preparation of (indolylmethyl)malononitriles via the one-pot three-component reaction of an aldehyde, malononitrile and indole in the presence of Zn(OAc)₂/NaOAc under silent and ultrasonic conditions. The reaction further proceeds through oxidative elimination under solvent-free conditions in the presence of Ca(OCl)₂ to furnish indolylacrylonitriles in high yields and short reaction times.     

Fragmentation of chloroperoxides: hypochlorite-mediated dehydration of hydroperoxyacetals to esters

Hypochlorites efficiently dehydrate hydroperoxyacetals to furnish the corresponding esters. The reaction, which can be accomplished with stoichometric Ca(OCl)₂ or with catalytic amounts of t-BuOCl, appears to involve formation and heterolytic fragmentation of secondary chloroperoxides, species not previously described in solution chemistry.     

Reaction of tert-butyl hypochlorite with carbonium ion from styrene epoxide in an acidic alcoholic solution

The kinetic regularities of the change in the concentration of tert-butyl hypochlorite in the presence of the binary system (BS) styrene epoxide??p-toluenesulfonic acid in a tert-butanol solution were studied using iodometry and HPLC and compared with the data obtained earlier for hydroperoxide decomposition. The expressions for the rates of transformation of Bu^tOCl, epoxide, and ROOH in the BS through the reactant concentrations are of the same type (the first order for the acid and the zero order for epoxide, Bu^tOCl, and ROOH) and indicate that the reactions are related to epoxide heterolysis. Dioxygen ceases ROOH decomposition in the BS but exerts no effect on the decrease in the concentration of Bu^tOCl, which efficiently inhibits the O₂ uptake in the BS and almost an order of magnitude retards the accumulation of benzaldehyde (the product of styrene epoxide oxidation) with a low (up to 15%) decrease in the heterolysis rate. The inhibition effect is due to the heterolytic interaction of Bu^tOCl with the carbocation formed by the cleavage of the three-membered ring of protonated styrene epoxide. The introduction of Bu^tOCl in the BS decreases the stationary concentration of the carbocation and, as a consequence, the stationary concentration of phenylcarbene responsible for O₂ uptake.     

Selective method for the preparation of 5-chloropentan-2-one

A selective method for the preparation of 5-chloropentan-2-one by interaction of 1-methylcyclobutanol with Ca(OCl)₂ followed by decomposition of the hypochlorite thus obtained in the presence of Fe^II salt is proposed. The selectivity of the ketone formation from the alcohol is 98%, while the conversion of the alcohol is 35–40%.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 774–776, April, 1995.     

Circumventing the OCl versus OOH scaling relation in the chlorine evolution reaction: Beyond dimensionally stable anodes

The development of selective electrocatalysts for the chlorine evolution reaction (CER) is majorly restrained by a scaling relation between the OCl and OOH adsorbates, rendering that active CER catalysts are also reasonably active in the competing oxygen evolution reaction (OER). While theory predicts that the OCl versus OOH scaling relation can be circumvented as soon as the elementary reaction steps in the CER comprise the Cl rather than the OCl adsorbate, it was demonstrated recently that PtN₄ sites embedded in a carbon nanotube follow this theoretical prediction. Advanced experimental analyses illustrate that the PtN₄ sites also reveal a different reaction kinetics compared to the industrial benchmark of dimensionally stable anodes (DSA). A reverse Volmer–Heyrovsky mechanism was identified, in which the rate-determining Volmer step for small overpotentials is followed by the kinetically limiting Heyrovsky step for larger overpotentials. Since the PtN₄ sites excel DSA in terms of activity and chlorine selectivity, we suggest the Cl intermediate as well as the reverse Volmer–Heyrovsky mechanism as the design criteria for the development of next-generation electrode materials beyond DSA.     

Regioselectivity of the oxygen addition-induced dechlorination of PCBS and DDT metabolites in electron capture mass spectrometry

The electron capture mass spectra of 28 ³⁵Cl-labeled polychlorinated biphenyls (PCBs) and 4 ³⁷Cl-labeled 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) metabolites were obtained by using a 20% oxygen in methane mixture as the reagent gas. The degree of regioselectivity of the PCB oxygen addition-induced dechlorination reaction was determined by measurement of the residual amount of label in the M-19 ions produced by addition of O₂ and subsequent loss of OCl from the molecule. Chlorine was lost in a random manner from the PCBs, contrary to the dechlorination reaction observed when methane alone was used. For the DDT metabolites, many dechlorination reactions were observed in addition to the one that generated the M-19 ions. Loss of Cl, loss of Cl₂, and addition of O₂ with the loss of one or two HCl molecules also were seen. These various dechlorination reactions involved only the aliphatic chlorines. Addition of O₂ followed by loss of Cl at the beta position of 2,2-bis(4-³⁷Cl-chlorophenyl)-1-chloroethylene and 2,2-bis(4-³⁷Cl-chlorophenyl)-1,1-dichloroethylene may be due to the ability of the diphenyl methane moiety to stabilize the intermediates. Formation of an ion that corresponds to 4,4′-dichlorobenzophenone also was observed for three of these labeled DDT metabolites.     

Die Kristallstrukturen von α- und β-K3OCl

The Crystal Structures of α- and β-K₃OCl The orange coloured compound K₃OCl has been prepared. It exists in a low temperature modification (α-K₃OCl) and a high temperature modification (β-K₃OCl). The transition temperature is 364 ± 5 K. The crystal structures were determined by x-ray diffraction. α-K₃OCl crystallizes at room temperature in the orthorhombic space group Pbnm (Z = 4) with the cell parameters a = b = 723.9(2) pm and c = 1 027.7(2) pm in the anti-GdFeO₃-structure type. The high temperature modification β-K₃OCl crystallizes (Z = 1) in the cubic space group Pm3m in the β-Ag₃SI-structure type with a = 516.2(2) pm (T = 393 K).     

Chlorofluorieren mit Trifluormethylhypochlorit CF3OCl. Darstellung und spektroskopische Charakterisierung von Trifluormethyliodchloridfluorid CF3I(Cl)F

Chlorofluorinate with Trifluoromethylhypochlorite CF₃OCl. Preparation and Spectroscopic Characterization of Trifluormethyliodinechloridefluoride CF₃I(Cl)F The preparation of a new iodine(III) compound, trifluormethyliodinechloridefluoride CF₃I(Cl)F, via oxidative addition of trifluoromethylhypochlorite CF₃OCl to trifluoromethyliodide CF₃I is described. The thermolabile compound has been characterized by i.r., Raman, ¹⁹F NMR, and mass spectroscopy.     

A Practical Catalytic Procedure for Oxidation of Alcohols Into Aldehydes or Ketones with RuCl3/Water and Ca(OCl)2 or NaIO4

Ruthenium complexes catalyze the oxidation of alcohols to the corresponding ketones or aldehydes when Ca(OCl)₂ or NaIO₄ are used as oxygen donors in the presence of water (5–10 equiv.). The reactions take place at room temperature affording products in yields of 45–80%.     

An ab initio study of the structures and energetics of CH3OCl and CH3ClO

The equilibrium structures, vibrational spectra, and heats of formation for CH₃OCl and CH₃ClO have been estimated using high levels of ab initio molecular orbital theory. The lowest energy isomer is found to be CH₃OCl, and its heat of formation is estimated to be −13.5±2 kcal mol⁻¹, in good agreement with bond additivity estimates. Results for the CH₃ClO isomer are presented for the first time, and it is found to be 40.5 kcal mol⁻¹ higher in energy relative to CH₃OCl. ©1999 John Wiley & Sons, Inc. Int J Quant Chem 73: 29–35, 1999     

Spectroscopic properties and luminescence concentration quenching of the Pr3+ ion in La1−xPrxOCl

Luminescence spectra ofLa_1−xPr_xOCl(0.01 ≤ x ≤ 0.3) were recorded at liquid helium and room temperature. From these spectra, the energy level diagram of Pr³⁺ in LaOCl was deduced. The decay times of the Pr³⁺ emission in La_1−xPr_xOCl were measured using a high-resolution dye laser system. The linear concentration quenching and exponential decay times are explained assuming cross relaxation and energy transfer between the Pr³⁺ ions.     

Advanced Statistical Optimization of Parameters of Synthesis Process of Oxygenated Carbonated Apatite

The synthesis process of oxygenated carbonated apatite was optimized by an advanced statistical planning of experiments. Full factorial design of 24 experiments was used to find the effects of five principal parameters: pH of the reaction medium, atomic ratio Ca/P of the reagents, concentration of the calcium solution (Ca²⁺), temperature of the reaction medium (T) and duration of the reaction (D), with fixing the H₂O₂ composition at 30% and stirring to 600 turns/min. Studied responses were the atomic ratio Ca/P, % O₂, % O₂ ^2? and % CO_{3 2?}. Optimum synthesis parameters were found to be pH = 7.38, Ca/P = 1.647, [Ca2+] = 0.636 M, T = 40°C and D = 1 h. The prediction responses were Ca/P = 1.575, % O₂ = 0.76, % O₂ ^2? = 0.50 and % CO₃ ^2?= 1.84. The actual experimental results were in agreement with the prediction.     

Kinetics of metal exchange reaction of Cu(II)-poly(vinyl alcohol) complex with Ca(II)-ethylenediamine-N,N,N′,N′-tetraacetic acid in aqueous solution

The kinetics of the metal exchange reaction between the Cu(II)-poly(vinyl alcohol) complex (Cu(II)-PVA) and Ca(II)-ethylenediamine-N,N,N′,N′-tetraacetic acid (Ca(II)-EDTA) were studied by mixing both solutions in a spectrophotometer at pH 9.7–11.0, at μ = 0.10(KNO₃) and at 25°C. The reaction is initiated by the formation of unstable Cu(II)-H-PVA by the attack of H⁺ to Cu(II)-PVA, and while both ligand exchange and metal exchange steps occur, the latter may be rate-determining. The kinetic expression of this reaction was determined as -d[Cu(II)-PVA]/dt = k[Cu(II)-PVA] [H⁺] [PVA]/[Ca(II)-EDTA], where k = k₁ + k′₂[H⁺], k₁ = 3.85 × 10⁻² sec⁻¹, k₂ = k′₂ · K^−H_Cu(II)-H-PVA 9.59 × 10⁵ 1 mol⁻¹ sec⁻¹.     

La3OCl[AsO3]2: Ein Lanthan‐Oxidchlorid‐Oxoarsenat(III) mit “lone‐pair”‐Kanalstruktur

La₃OCl[AsO₃]₂: A Lanthanum Oxide Chloride Oxoarsenate(III) with a “Lone‐Pair” Channel Structure La₃OCl[AsO₃]₂ was prepared by the solid‐state reaction between La₂O₃ and As₂O₃ using LaCl₃ and CsCl as fluxing agents in evacuated silica ampoules at 850 °C. The colourless crystals with pillar‐shaped habit crystallize tetragonally (a = 1299.96(9), c = 558.37(5) pm, c/a = 0.430) in the space group P4₂/mnm (no. 136) with four formula units per unit cell. The crystal structure contains two crystallographically different La³⁺ cations. (La1)³⁺ is coordinated by six oxygen atoms and two chloride anions in the shape of a bicapped trigonal prism (CN = 8), whereas (La2)³⁺ carries eight oxygen atoms and one Cl^? anion arranged in the shape of tricapped trigonal prism (CN = 9). The isolated pyramidal [AsO₃]^3? anions (d(As–O) = 175–179 pm) consist of three oxygen atoms (O2 and two O3), which surround the As³⁺ cations together with the free, non‐binding electron pair (lone pair) Ψ¹‐tetrahedrally (?(O–As–O) = 95°, 3×). One of the three crystallographically independent oxygen atoms (O1), however, is exclusively coordinated by four (La2)³⁺ cations in the shape of a real tetrahedron (d(O–La) = 236 pm, 4×). These [(O1)(La2)₄]¹⁰⁺ tetrahedra form endless chains in the direction of the c axis through trans‐edge condensation. Empty channels, constituted by the lone‐pair electrons of the Cl^? anions and the As³⁺ cations in the Ψ¹‐tetrahedral oxoarsenate(III) anions [AsO₃]^3?, run parallel to [001] as well.     

Oxidation of Aqueous Unsymmetrical Dimethylhydrazine by Calcium Hypochlorite or Hydrogen Peroxide/ Copper Sulfate

Abstract

The oxidative destruction of unsymmetrical dimethylhydrazine (UDMH) by a molar excess of Ca(OCl)₂ leads mainly to formaldehyde dimethylhydrazone and tetramethyl tetrazene, but not to N-nitrosodi-methylamine (NDMA). An alternate method using H₂O₂/CuSO₄ leads to ca. 25% NDMA. The amount of UDMH destroyed is affected by the order of addition of the H₂O₂, and CuSO₄: when the CuSO₄ is added first, only ca. 65% of the UDMH is destroyed, while the reverse order of addition leads to 100% destruction of UDMH.     

[{μ‐Cy8Si8O13}2Ca(DME)Ca(THF)2] – The First Metallasilsesquioxane Derivative of a Heavier Alkaline Earth Metal

[{μ‐Cy₈Si₈O₁₃}₂Ca(DME)Ca(THF)₂] ( 2 ), the first metallasilsesquioxane derivative of a heavier alkaline earth metal, has been prepared by a reaction of Cy₇Si₇O₉(OH)₃ ( 1 ) with metallic Ca in liquid ammonia / THF followed by recrystallization from DME. In the course of the reaction ligand rearrangement under formation of the (Cy₈Si₈O₁₃)^? dianion takes place. In the dinuclear calcium complex 2 the anionic silsesquioxane cages act as bridging ligands. The Ca²⁺ ions are unsymmetrically coordinated by THF and DME molecules.     

Development of a method based on inductively coupled plasma-dynamic reaction cell-mass spectrometry for the simultaneous determination of phosphorus,calcium and strontium in bone and dental tissue

A method, based on the use of a quadrupole-based inductively coupled plasma-mass spectrometry instrument equipped with a quadrupole-based collision/reaction cell (dynamic reaction cell, DRC), was developed for the simultaneous determination of phosphorus, calcium and strontium in bone and dental (enamel and dentine) tissue. The use of NH₃, introduced at a gas flow rate of 0.8 mL min^− 1 in the dynamic reaction cell, combined with a rejection parameter q (RPq) setting of 0.65, allows interference-free determination of calcium via its low-abundant isotopes ⁴²Ca, ⁴³Ca and ⁴⁴Ca, and of strontium via its isotopes ⁸⁶Sr and ⁸⁸Sr that are freed from overlap due to the occurrence of ArCa⁺ and/or Ca₂⁺ ions. Also the determination of phosphorus (³¹P, mono-isotopic) was shown to be achievable using the same dynamic reaction cell operating conditions. The bone certified reference materials NIST SRM 1400 Bone Ash and NIST SRM 1486 Bone Meal were used for validation of the measurement protocol that was shown capable of providing accurate and reproducible results. Detection limits of P, Ca and Sr in dental tissue digests were established as 3 µg L^− 1 for P, 2 µg L^− 1 for Ca and 0.2 µg L^− 1 for Sr. This method can be used to simultaneously (i) evaluate the impact of diagenesis on the elemental and isotopic composition of buried skeletal tissue via its Ca/P ratio and (ii) determine its Sr concentration. The measurement protocol was demonstrated as fit-for-purpose by the analysis of a set of teeth of archaeological interest for their Ca/P ratio and Sr concentration.     

关于在钾与负氢混合物中钾钙嬗变的检测

报道了在室温下钾与负氢混合物中钾钙发生嬗变的现象，负氢是由NaBH₄、LiBH₄和NH₃BH₃提供的.实验中的钾和钙的浓度分别用诱导耦合等离子发射光谱法（ICP-OES）和诱导耦合等离子质谱法（ICP-MS）进行检测.ICP-OES结果表明随着混合物中钾浓度的降低伴随着钙的浓度增加.此外ICP-MS结果还表明⁴⁰Ca浓度的增加伴随着⁴¹K浓度的增加，可能表明在负氢存在的条件下混合物中⁴⁰Ca的生成与⁴¹K物种有关.     

Zur Kenntnis des Verhaltens der Oxidsulfate der Seltenen Erden gegen Chlorwasserstoff. II. Charakterisierung und thermisches Verhalten der Umsetzungsprodukte der Oxidsulfate mit Chlorwasserstoff

The reaction products of the oxide sulphates of rare earths with hydrogen chloride are mixtures of chlorides M^IIICl₃ and chloride-sulphates M^IIICl₃ and chloride-sulphates M^IIIClSO₄. By oxidation of these mixtures, oxide sulphates MO₂SO₄ are formed as final products. Intermediary products are mixtures of M^IIIOCl? M^IIIClSO₄.