On the behaviour of Eu oxo-species in molten NaBr–NaI (0.77:0.23) mixture at 973 K

The interaction of Eu₂O₃ with molten NaBr–NaI (0.77:0.23) mixture at 973 K was studied by sequential addition method with the use of YSZ membrane oxygen electrode for controlling of course of the process. The Red-Ox process is accompanied with formation of EuO in the melt. The total solubility of EuO (sum of concentration of Eu²⁺, O^2–, non-dissociated EuO) in the molten NaBr–NaI at 973 K (mole fraction 2.7 × 10^–4) is considerably lower than in pure NaI melt (4.2 × 10^–4), which can be explained using the ‘hole’ model by reduction of a number of holes of comparable with EuO particle size because of addition of smaller bromide ion to the iodide melt.

The solubility of EuO is appreciably affected by its dispersity and the value of surface energy causing these solubility changes is estimated as 37 J m^–2.     

An N-protection free ligation of the peptide thioester and the peptide with an N-alkoxy- or N-aryloxyamino group at its N-terminus

Peptides with an N-alkoxy or N-aryloxy amino acid at their N-terminus were synthesized and successfully ligated with a peptide thioester by silver ion activation under a slightly acidic condition without requiring protection of the side chain amino groups. The N-methoxy group was easily cleaved by the SmI₂ reduction in CH₃OH aq. to obtain the desired peptide with a native peptide bond. This method was successfully applied to the synthesis of the human atrial natriuretic peptide showing the efficiency of the novel ligation.     

KI与无机铵盐催化CO2与环氧丙烷合成碳酸丙烯酯

以无毒、合成简单、廉价的无机铵盐(氨基甲酸铵、碳酸氢铵、碳酸铵等)为助催化剂,研究其对卤化钾(KCl、KBr、KI)催化CO2与环氧丙烷合成碳酸丙烯酯(PC)的影响.结果表明,卤化钾与无机铵盐显示出很好的协同催化效应.其中以氨基甲酸铵为助催化剂,KI为主催化剂时,催化合成PC的效果最好.同时考察了催化剂用量、反应温度、CO2初始压力、PC的预加入量、反应时间等因素对反应的影响.在优化条件下,PC收率大于99%.     

Short-living absorption and emission of CsI(Na)

This paper investigates the short-living absorption and the emission of CsI(Na) under a pulsed electron beam (Е_e=0.25 MeV, t_1/2=15 ns and W=0.003…0.16 J/cm²). The bands of singlet self-trapped excitons, as well as Na⁰ and V_k color centers have been detected in the transient absorption spectrum of CsI(Na). It has been found that the activator luminescence spectrum, peaking at 3.0 eV, fits a Gaussian (E_m=3.0 eV and FWHM=0.44±0.02 eV at 80 K) and remains the same at different time delays within 10⁻⁸-10⁻³ s. The decay kinetics of the 3.0 eV emission has one nanosecond exponential component and two microsecond ones with time constants 1.0 and 3.0 μs, which remain unchanged within 78-150 K. It is concluded that the activator emission is due to the radiative annihilation of sodium-perturbed two halide excitons from the non-relaxed singlet state. The pathways of such excitons creation are discussed.     

Mild and efficient oxy-iodination of alkynes and phenols with potassium iodide and tert-butyl hydroperoxide

An efficient synthesis of 1-iodoalkynes and iodophenols was easily achieved by employing simple KI and TBHP. The reaction does not involve the use of a metal and base combination. A variety of substituted alkynes and phenols were prepared with good to excellent yield.     

State of Water in Hydration Spheres of Potassium Iodide

Ion hydration has been studied for potassium iodide solutions with concentrations from 0 to 51 wt.% at temperatures from 288.15 to 308.15 K based on ultrasonic measurements and molar adiabatic compressibility data. For hydration complexes, structural characteristics have been determined. The structure of noncoordinated water plays a significant role even in concentrated solutions. An electrostatic ion field has a strong effect on the temperature dependence of the molar volume of hydration water. A method for the precise determination of the total solvation boundary is presented.     

Synthesis and Crystal Structure of 3,5-Dicyano-2,6-diethylthiopyridine

3,5-Dicyano-2,6-diethylthiopyridine has been synthesized by the alkylation of cyanothioacetamide with ethyl iodide in DMF and its molecular and crystal structures have been investigated. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1351–1354, September, 2005.     

Neue quaternäre Chalkogenohalogenide

The quaternary chalcogeno halides AgHgSI, AgHgSBr and CuHgSI have been synthesized by annealing mixtures of silver (copper) halides and mercury sulphide. AgHgSI decomposes peritectoidally at 593±3 K and crystallizes in the orthohombic system with lattice constants ofa=772.3 (3),b=847.7 (3) andc=707.3 (3) pm. The phase diagram AgI-HgS resembles the AgI-Ag₂S system closely. Contrary to the literature the only stable compound in this system is AgHgSI. The previously mentioned Ag₂HgSI₂ is metastable. The reported compound Ag₂HgSBr₂ could not be synthesized. The substitution of Hg²⁺ by Cd²⁺ in CuHgSI leads to a red phase Cu₂Cd₃S₂I₄ which crystallizes in the wurtzite type structure with lattice parameters ofa=424.7 (1) andc=695.2 (1) pm.