Determination of activity coefficients using a flow EMF method. 1. HCl in methanol-water mixtures at 25, 35 and 45°C

A method to determine activity coefficients of electrolytes in mixed solvent is described which makes use of ion-selective electrode(s) (ISE) and in which a concentrated electrolyte solution is continuously added. Activity coefficients for HCl in methanol-water mixtures containing 0, 10, 20, 30, 50, 70, and 90 weight percent methanol at 25, 35 and 45°C were calculated using the Pitzer equation, and the electromotive force (emf) data of the cell: The experimental results agree well with literature values indicating that the proposed method is procise and reliable.     

Ceric Ammonium Nitrate as the Novel Oxidizing Agent for the Facile Synthesis of (Dichloroiodo)arenes

Ceric ammonium nitrate (CAN) has been found to be a remarkable oxidizing agent for the oxidative conversion of iodoarenes to (dichloroiodo)arenes in acetic acid using aqueous HCl. The reaction of CAN with HCl generates in situ molecular chlorine, which is responsible for the oxidation. This method avoids the use of hazardous, toxic, and corrosive gaseous chlorine.     

Simple and fast preparation of graphene oxide@ melamine terephthaldehyde and its PVC nanocomposite via ultrasonic irradiation: Chemical and thermal resistance study

Melamine terephthaldehyde modified graphene oxide (MTR-GO) with optimum content was easily prepared via ultrasonication method and used as anti-corrosion additive for Poly (vinyl chloride) (PVC). The effects of ultrasonicated MTR-GO on the mechanical, chemical and thermal resistance of the PVC were thoroughly studied. Change percentage of tensile strength and weight change percentage of PVC (P) and PVC/MTR-GO nanocomposite (PN) in acetone and sodium hypochlorite (NaClO) media at two different exposure temperature (20 °C and 50 °C) were examined. The PN sample showed lower change loss percentage of tensile strength in acetone uptake as compared with P sample at 20 °C. In higher temperature (50 °C), P sample was decomposed while PN still showed tensile data. The change loss percentage in tensile strength of PN sample showed 13% change at 50 °C in sodium hypochlorite while P sample showed 63% change for the parameter. Protective behavior of MTR-GO nanofiller on PVC matrix against thermal HCl releasing was investigated by Congo red tests. The results showed that the nanocomposite release less amount of HCl as compare to the neat PVC.     

Highly sensitive optical humidity probe

A highly sensitive optical humidity probe based on reflectance measurements has been developed using Nafion^®-crystal violet (CV) films. This sensor can be used to calibrate relative humidity (RH) in the range 0-0.25% with a detection limit (blank signal + 3σ_b, where σ_b = the standard deviation (S.D.) of the blank signal) of 0.018% RH (∼4.37 ppm) and exhibited low hysteresis. The sensor films were fully reversible in dry nitrogen and reversal times were shown to be dependent on exposure time and % RH. The response to 1% RH was highly reproducible (S.D. = 1.67%, number of samples (n) = 5). Hydrogen chloride gas did not interfere with the response of the sensor to RH but did reduce sensor reversal times. This sensor displayed sufficient sensitivity that it could be used to detect ppm levels of moisture in process gases such as nitrogen and HCl.     

Comparative study of NH4OH and HCl etching behaviours on AlGaN surfaces

A controlled AlGaN surface preparation method avails to improve the performance of GaN-based HEMT devices. A comparative investigation of chemical treatments by (1:10) NH₄OH:H₂O and (1:10) HCl:H₂O solutions for AlGaN surface preparation by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) is reported. The XPS data clearly reveal that the native oxide on AlGaN was composed of Al₂O₃, Ga₂O₃ and NO compounds. These compounds were etched off partially or completely by both the chemical treatments, namely NH₄OH or HCl solutions, independently. The HCl treatment etches out Al₂O₃ completely from native oxide unlike NH₄OH treatment. The HCl treatment results in larger amount of carbon segregation on AlGaN surfaces, however it removes all oxides’ compounds faster than NH₄OH treatment. The AFM results reveal the improvement of surface morphology by both the chemical treatments leading to the surface roughness RMS values of 0.24 nm and 0.21 nm for NH₄OH and HCl treated AlGaN layers, respectively.     

盐酸曲马多药物树脂制备技术的研究

采用静态法和动态法两种工艺制备盐酸曲马多药物树脂，并对制备过程中体系温度、反应时间、药物溶液浓度、溶液流速等影响因素进行了研究；以正交设计对工艺进行优化。     

含水混合溶剂中HCl活度系数的MSA计算

多组分体系热力学性质的研究是人们感兴趣的课题.七十年代初在Debye-Hückel 理论及统计力学的基础上发展起来的Pitzer 理论,不但解决了多组分体系中电解质的活度系数问题,而且还可以适用于真正的中高浓度.但该理论所涉及到的表征粒子间相互作用的三个参数必须通过精确的实验数据并采用可靠的拟合方法方可求得.七十年代后期发展起来的平均球近似(MSA)方法是一种计算电解质水溶液的热力学性质的有效方法.近年来,国外已有人将这种方法应用于单一或混合电解质水溶液中电解质活度系数的计算并取得了令人满     

Structure of (DMF)<Subscript>m</Subscript>(HCl)<Subscript>n</Subscript> complexes (<Emphasis Type="Italic">m</Emphasis>= 2, <Emphasis Type="Italic">n</Emphasis> = 3–4)

(DMF)₂(HCl)₃ and (DMF)₂(HCl)₄ heterocomplexes were studied for the first time in terms of the B3LYP/6-31++G(d, p) density functional calculation. The resulting data about their structure, stability, strength of intermolecular bonds, and degree of proton transfer in O...H...Cl bridges are compared with the results of a similar calculation fulfilled for (DMF)_m(HCl)_n clusters (m, n = 1–2) and with the experimental data on the structure and properties of acid-base complexes in DMF solutions of HCl. An extremely stable symmetrical cycle of four molecules — (DMF)₂(HCl)₂ — is assumed to be a structure-forming element of solution in the DMF-HCl system in the range of concentrations achievable under normal conditions. When [HCl]₀ > [DMF]₀, the “excess” hydrogen chloride molecules add to the chlorine atoms of this cycle, forming heterocomplexes with a branched structure. Addition of more HCl molecules to the (DMF)₂(HCl)₂ cycle appreciably increases the degree of proton transfer from acid to base molecule.     

Reaction of [P3N3Cl4(NH2)2] with [HN(POCl2)2]; The crystal structure of the phosphazenium salt [P3N3HCl4(NH2)2]+[N(POCl2)2]−

The reaction of diaminotetrachloro-cyclotriphosphazene with tetrachloride of μ-imino-diphosphoric acid leads to the formation of the salt-like compound [P₃N₃HCl₄(NH₂)₂]⁺[N(POCl₂)₂]⁻ which identity was unambiguously established by means of X-ray structure analysis. The structure is composed of [P₃N₃HCl₄(NH₂)₂]⁺ cations and [N(POCl₂)₂]⁻ anions joined by a system of H-bonds. As in other phosphazenium salts, the protonation of the ring N atom leads to significant changes in the endocyclic P N bond lengths.     

Raman spectra of complexes of HCl with DMF with a strong quasisymmetric H-bond in solutions

Raman spectra of complexes of HCl with DMF with a strong quasisymmetric H-bond in solutions were obtained. The formation of these complexes is accompanied by significant changes in almost all the vibration frequencies and line intensities, the changes in Raman and IR spectra being similar in many features. A weak background scattering was found in the Raman spectra, which coincides in shape with the continuous absorption in IR spectra.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1593–1595, September, 1994.This work was supported by the Russian Foundation for Basic Research (Project No. 93-03-18856).