亚硫酸盐无氰电沉积金新工艺及机制

直接以氯金酸作为主盐、 羟基乙叉二膦酸（HEDP）作为镀液稳定剂和镀层细化剂、 结合添加剂, 组成亚硫酸盐无氰镀金新工艺; 研究镀液稳定性、 镀层形态及金电沉积机制。结果表明, HEDP可明显提升镀液稳定性;不含HEDP的亚硫酸盐镀金液中, 镀层呈棒状晶粒并随沉积时间延长而逐渐生长,导致镀层外观随镀层厚度增加由金黄色转变为红棕色。镀液含有HEDP时, 金晶粒形态由棒状转变为棱锥状, 且棱锥状晶粒随沉积时间延长生长速率较小, 镀层厚度为1 μm时仍呈现金外观。电化学实验表明金电沉积不经历成核过程。     

Kinetics and Mechanism of the Reaction of a Ruthenium(VI) Nitrido Complex with HSO3− and SO32− in Aqueous Solution

The kinetics and mechanism of the reaction of S^IV (SO₃^2?+HSO₃^?) with a ruthenium(VI) nitrido complex, [(L)Ru^VI(N)(OH₂)]⁺ (Ru^VIN, L=N,N′‐bis(salicylidene)‐o‐cyclohexyldiamine dianion), in aqueous acidic solutions are reported. The kinetic results are consistent with parallel pathways involving oxidation of HSO₃^? and SO₃^2? by Ru^VIN. A deuterium isotope effect of 4.7 is observed in the HSO₃^? pathway. Based on experimental results and DFT calculations the proposed mechanism involves concerted N?S bond formation (partial N‐atom transfer) between Ru^VIN and HSO₃^? and H⁺ transfer from HSO₃^? to a H₂O molecule.     

Sensitive Determination of 2‐Methoxyestradiol in Pharmaceutical Preparations and Biological Fluids by KMnO4‐Na2SO3 Chemiluminescence System

A simple and novel flow‐injection chemiluminescence (FI‐CL) method was established for the determination of 2‐Methoxyestradiol (2‐ME) in pharmaceutical preparations and biological fluids. The method was based on the significant enhancement of the CL from the KMnO₄‐Na₂SO₃ reaction by 2‐ME in acidic medium. Under optimized conditions, the CL intensity was correlated linearly with concentration of 2‐ME in the range of 5.0 × 10^?8‐5.0 × 10^?6 M (r = 0.9995). The detection limit (3σ) of 2‐ME was 7.5 × 10^?9 M and the relative standard deviation was 0.8% at 5.0 × 10^?7 M 2‐ME (n = 8). The proposed method was successfully applied for the flow‐injection CL determination of 2‐ME in pharmaceutical preparations and biological fluids with the recoveries from 92.4 to 106.8%. The possible CL reaction mechanism was also discussed briefly.     

A Novel and Efficient Synthesis of 2,3-Dichloroquinoline

2,3-Dichloroquinoline was prepared in three steps in good overall yield from commercial 3-bromoquinoline via N-oxide formation and rearrangement to 3-bromocarbostyril, followed by a one-pot conversion to 3-bromo-2-chloroquinoline and halogen exchange to the title compound.     

Microwave-Assisted Direct Synthesis of 4H-1,2,4-Benzothiadiazine 1,1-Dioxide Derivatives

Abstract

We describe a rapid and convenient methodology for the preparation of diverse 3-aryl and 3-trifluoromethyl 4H-1,2,4-benzothiadiazine-1,1-dioxides in a one-pot microwave-promoted reaction between 2-aminobenzenesulfonamides and benzaldehydes, trifluoroacetic acid or benzoic acids.

GRAPHICAL ABSTRACT      

Application of metalloporphyrins and methylviologen-pendent iron porphyrin to reduction of diphenylsulfoxide

In the two-electron reduction of diphenylsulfoxide to diphenylsulfide, which is considered a model reaction of sulfite reduction catalyzed by sulfite reductase, methylviologen-pendent iron(III) porphyrin exhibits much higher catalytic activity than usual iron(III) and manganese(III) tetraphenylporphyrins, while cobalt(II) tetraphenylporphyrin exhibits much less catalytic activity than the others. Discussion about the active species and the reason of the acceleration by methylviologen-pendent is presented.     

Formation of 4-arylpyridines from pyridinium salts under the action of methylammonium sulfite

Reactions of pyridinium salts or nonquaternized pyridine with 4-methylpyridinium salts in the presence of methylammonium sulfite in aqueous methylamine afford 4-phenylpyridine in 29—57% yields. The probable mechanism of ring transformation in simplest pyridine derivatives under the action of nucleophiles is discussed.     

NMR and EPR studies of the reaction of nucleophilic addition of (bi)sulfite to the nitrone spin trap DMPO

The reaction of the nitrone spin trap 5,5‐dimethylpyrroline‐N‐oxide (DMPO) with sodium (bi)sulfite in aqueous solutions was investigated using NMR and EPR techniques. Reversible nucleophilic addition of (bi)sulfite anions to the double bond of DMPO was observed, resulting in the formation of the hydroxylamine derivative 1‐hydroxy‐5,5‐dimethylpyrrolidine‐2‐sulfonic acid, with characteristic ¹H and ¹³C NMR spectra. The reaction mechanism was suggested and corresponding equilibrium constants determined. The mild oxidation of the hydroxylamine results in the formation of an EPR‐detected spectrum identical with that for the DMPO adduct with sulfur trioxide anion radical. The latter demonstrates that a non‐radical addition reaction of (bi)sulfite with DMPO may contribute to the EPR detection of SO₃^?? radical. This possibility must be taken into account in spin trapping analysis of sulfite radical. Copyright © 2003 John Wiley & Sons, Ltd.     

水发食品中甲醛含量快速检测的实验研究

利用品红亚硫酸钠溶液与醛类物质反应后颜色深浅与浓度成正比的原理,使用5种标准浓度的甲醛溶液与希夫试剂反应显色后制作标准比色卡。用待测样品显色后的溶液与制作的标准比色卡进行比对,判断甲醛浓度范围。该方法具有现象明显、灵敏准确、药品易得的优点。因此,可用作中学生课外兴趣实验的实施项目,配制的希夫试剂和制作的标准比色卡也可用于家庭检测水发食品中甲醛含量。