Mittlere Schwingungsamplituden der Hexachloro- und Hexabromo-Anionen einiger Lanthanide

Mean amplitudes of vibration for various octahedral complex compounds of the typeLnCl₆ ^3– andLnBr₆ ^3– (withLn=Nd, Eu, Gd, Dy, Er, and Yb) have been calculated, at different temperatures, using known spectroscopic data. The results are briefly discussed and it is found that theLn–Cl andLn–Br amplitude values are highly characteristic.

     

Luminol chemiluminescence HPLC reaction detector for amino acids and other ligands

A detector for HPLC is based on suppression of chemiluminescence from the Cu(II)-luminol-peroxide reaction. Analytes which complex Cu(II) reduce the free Cu(II) concentration and thus the observed chemiluminescence intensity. The degree of chemiluminescence suppression is a measure of the analyte concentrations. Detection limits are in the range of 1 pmole-1 nmole for amino acids (both primary and secondary without derivatization), CN^–, amines, catecholamines, catechol, and aminoglycoside antibiotics. The detection approach is demonstrated with an ion-exchange separation of amino acids, a reverse phase separation of catecholamines, and an ion-pair separation of the three components of gentamicin C in commercial gentamicin sulfate.     

Aminolysis ofO-alkylO-4-nitropyenyl chloromethylphosphonates in reverse micellar solutions of the nonionic surfactant

The reaction ofn-hexylamine withO-alkylO-4-nitrophenyl chloromethylphosphonates in toluene solutions of poly(ethylene glycol)-600 monolaurate (PM) has been studied by spectrophotometry. The reverse micelles of the nonionic surfactant increase more than tenfold the observed rate constant of aminolysis. The catalytic activity of the surfactant is practically independent of the alkyl radical length of phosphonate. An increase in the concentration of amine results in a decrease in the catalytic efficiency. The character of the dependence of the rate constant on the concentration of PM is affected by the alkyl chain length of the substrate. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1735–1738, September, 1998.     

Molecular Structure of 1,3,5-Tris (Trimethylstannyl) Benzene: An Electron Diffraction Study

The molecular structure of 1,3,5-tris (trimethylstannyl) benzene has been determined by gas-phase electron diffraction. The C — C bond length is in good agreement with that in benzene. In agreement with the somewhat electron-releasing character of the substituents, the endocyclic bond angles at the substituents are somewhat smaller than 120°. The mean value of Sn — C bond lengths is greater than that in tetraphenyltin and tetramethyltin. The SnMe₃ groups appear freely rotating around the C_aryl — Sn bonds. The following bond lengths (r _g) and bond angles were determined: (Sn — C)_mean 2.150 ± 0.007 Å, C — C 1.399 ± 0.005 Å, (C — H)_mean 1.105 ± 0.006 Å, < C — C(Sn) — C 117.7 ± 1.7º, < C_aryl — Sn — C_methyl 106.7 ± 0.7º < Sn — C — H 111.5 ± 0.9º.     

Volume and compressibility changes of complex formation between 18-Crown-6 and NaCl,KCl, and CsCl in water

The apparent molal volumes and compressibilities of NaCl, KCl, and CsCl in mixtures of 18-Crown-6 and water have been calculated from density and speed-of-sound measurements at 25°C. The partial molal volumes and compressibilities of the salts when all cations have formed complexes with 18-Crown-6 molecules have been evaluated. The sign and magnitude of the volume and compressibility changes of complex formation strongly suggest that the charge of the cation becomes very effectively screened by the crown ether.     

Enhanced Acid/Base Catalysis in High Temperature Liquid Water

High temperature liquid water (HTLW), as an environmentally benign medium, has drawn increasing attention for organic chemical reactions and biomass conversion1-3. HTLW has a strong tendency to ionize and can act as an acid and/or base catalyst. In addition, HTLW can dissolve organic compounds to some extent allowing for a homogenous reaction within an aqueous phase. Extensive researches4-10 have been pursued on acid/base-catalysis reactions in HTLW without addition of acid or base. Howe…     

N,N''''-双(4-甲基-2-苯并噻唑基)-2,6-吡啶二酰胺钴(Ⅱ) 配合物的合成和晶体结构

0IntroductionCobaltcomplexeswithnonmacrocyclicchelatingligandscontainingtheamidefunctionalityhavere鄄ceivedmuchattentioninpastyears[1~3].Somestudieshaverevealedthatdeprotonatednitrogensoforganicamides,beinganionicinnature,arecapableofstabi鄄lizingthetriva…     

Oxidation of some catecholamines by sodium N-chloro-p-toluenesulfonamide in acid medium: A kinetic and mechanistic approach

The kinetics of the oxidation of five catecholamines viz., dopamine (A), L-dopa (B), methyldopa (C), epinephrine (D) and norepinephrine (E) by sodium N-chloro-p-toluenesulfonamide or chloramine-T (CAT) in presence of HClO₄ was studied at 30±0.1 °C. The five reactions followed identical kinetics with a first-order dependence on [CAT] _o , fractional-order in [substrate] _o , and inverse fractional-order in [H⁺]. Under comparable experimental conditions, the rate of oxidation of catecholamines increases in the order D>E>A>B>C. The variation of ionic strength of the medium and the addition of p-toluenesulfonamide or halide ions had no significant effect on the reaction rate. The rate increased with decreasing dielectric constant of the medium. The solvent isotope effect was studied using D₂O. A Michaelis-Menten type mechanism has been suggested to explain the results. Equilibrium and decomposition constants for CAT-catecholamine complexes have been evaluated. CH₃C₆H₄SO₂NHCl of the oxidant has been postulated as the reactive oxidizing species and oxidation products were identified. An isokinetic relationship is observed with β=361 K, indicating that enthalpy factors control the reaction rate. The mechanism proposed and the derived rate law are consistent with the observed kinetics.     

2,6-二氯-4-乙酰基苯基磷酸的合成

制备了酸性磷酸酶检测底物2，6-二氯-4-乙酰基苯基磷酸酯（DCAP-P）。以2，6-二氯苯酚为原料，经酰化反应、AlCl3催化F-C重排、碱化成盐、磷酯化、水解等5步反应，制备了DCAP-P，并对F-C重排、磷酯化条件进行了改进。