On gold extraction from rebellious ores

The paper generalizes research findings on application of chemical additives to stage-by-stage processing of rebellious gold-bearing ores. The designed stages of gold extraction intensification are the controlled mineral alteration by preparation, use of conventional and specific collecting agents to prepare mineral surface to sorption to intensify flotation, creation of selective collecting agents, and cyanation optimization by introducing additional oxidation agents. __________ Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 2, pp. 102–109, March–April, 2009.     

Nickel-Catalyzed Reductive Coupling of Vinyl Triflates and 1,4-Dicyanobenzene to Access Alkenyl Nitriles

We report a vinyl cyanation reaction of vinyl triflates and readily available 1,4-dicyanobenzene through a nickel-catalyzed reductive coupling process. The reaction is operated under mild conditions with remarkable functional-group compatibility. Cyclic vinyl triflates with various ring sizes and substituents at different positions all reacted smoothly. The synthetic utility is demonstrated by the derivatization of pharmaceutical and natural compounds, a scale-up synthesis, and various functional group transformations. Preliminary mechanistic studies demonstrate that vinyl triflates are more reactive than 1,4-dicyanobenzene towards the oxidative addition to nickel catalyst.     

A Versatile Protocol for Copper‐Catalyzed Cyanation of Aryl and Heteroaryl Bromides with Acetone Cyanohydrin

A novel copper‐catalyzed cyanation of aryl and heteroaryl bromides using acetone cyanohydrin has been developed.     

黄金选矿的技术现状及发展趋势

介绍了目前的黄金主要选矿技术,对未来黄金选矿技术发展方向做出展望。     

A highly efficient polymer‐anchored palladium(II) complex catalyst for hydrogenation,Heck cross‐coupling and cyanation reactions

BACKGROUND: Precise architectures of steric and electronic properties of palladium species play a crucial role in designing highly functionalized catalyst systems responsible for target organic transformations. Pd catalysts supported on polymer materials have been employed extensively as catalysts not only for hydrogenation but also for coupling reactions in the production of fine chemicals. RESULTS: A new polymer‐anchored Pd(II) complex has been synthesized and characterized. The catalyst shows high catalytic activity in the hydrogenation of styrene oxide, Heck cross‐coupling and cyanation reactions of aryl halides. The effect of various reaction parameters were investigated to optimize reaction conditions. The catalytic system shows good activity in the hydrogenation of styrene oxide (conversion 98%) with a selectivity to 2‐phenylethanol (93%) which is higher than its homogeneous analogues. The catalyst also exhibits excellent catalytic activity for the Heck cross‐coupling and cyanation reactions of various substituted and non‐substituted aryl halides. CONCLUSIONS: Results demonstrate that the catalyst is robust and stable and can be recovered quantitatively by simple filtration and reused several times without loss of activity. Copyright © 2010 Society of Chemical Industry     

Rhodium(III)‐Catalyzed Selective C?H Cyanation of Indolines and Indoles with an Easily Accessible Cyano Source

The rhodium‐catalyzed selective cyanation of C H bonds of indolines and indoles with N‐cyano‐N‐phenyl‐para‐methylbenzenesulfonamide is described. This protocol offers a facile access to C‐7 cyanated indolines and C‐2 cyanated indoles with high site selectivity and excellent functional group tolerance.

     

促进亚铁氰化钾中氰基游离的机理

亚铁氰化钾作为氰化试剂具有无毒、廉价和后处理简单等多种优点,逐渐成为研究的热点。由于氰基与铁的结合能力很强,造成氰基很难游离出来,反应常需要昂贵的催化剂和高温等条件,促进亚铁氰化钾中氰基的游离可降低条件、提高产率。研究发现在反应体系中加入水、弱碱或ZnBr2可以促使氰基从亚铁氰化钾中游离,并对其作用机理进行了探析。     

酰基腈合成方法研究进展

阐述了一类重要的化合物酰基腈的合成方法的发展概况     

3-氯-4-三氟甲氧基苯甲腈的合成

以3-氯-4-三氟甲氧基苯胺为原料,经重氮化、甲醛肟化、水解和腈化反应得到纯度≥99.2%(GC)的3-氯-4-三氟甲氧基苯甲腈,总收率为31.5%。中间体及产物结构通过 IR 及元素分析验证。产物色泽好,腈化反应的溶剂可回收使用3次。