Active nickel-based reduction of organic compounds

The reducing system NiCl₂·2H₂O—Li—arene_cat (cat is catalyst) was proposed for use to reduce a wide range of organic compounds, including alkenes, alkynes, carbonyl compounds, imines, halogenated derivatives, sulfonates, aromatic compounds, hydrazines, azo and azoxy compounds, N-oxides, and nitrones. The degree of reduction can be controlled for some substrates. Deuterium can be incorporated in the reaction products using nickel chloride deuteriohydrate. Nitrones, N-alkoxyamides, and acyl azides are also reduced with the Li—arene_cat system containing no nickel salt.     

Synthesis of nitro and amino derivatives of benzothiacrown ethers

The condensation reaction of 1,2-bis(2-haloethoxy)-4-nitrobenzenes with acyclic α,ω-(oxa)alkanedithiols in the presence of alkali metal carbonates produced a series of nitrobenzodithiacrown ethers with macrocycles of different size. The structures of three ethers were established by X-ray diffraction. A new method was developed for the synthesis of nitrobenzomonothia-15-crown-5 ether. Nitro derivatives of benzodithiacrown ethers were tested as reagents for extraction of palladium(II), platinum(IV), and rhodium(III) from hydrochloric acid solutions. Extraction of Pd^II salts was found to be highly selective compared to that of Pt^IV and Rh^III salts. Benzodithia-15-crown-5 ether is the most efficient extractant for palladium(II). Reduction of nitrobenzothiacrown ethers with hydrazine hydrate in the presence of a platinum catalyst afforded their amino derivatives. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 958–966, May, 2007.     

Determination and fractionation of sulphur in a contaminated dredged sediment

Conversion of sulphur compounds in reduced, contaminated sediments that are brought in upland conditions may largely affect the potential mobility of heavy metal contaminants. We applied selected methods for the determination of total sulphur and sulphur fractions in a contaminated sediment in the reduced state and after gradual drying and oxidation during 1 month. Dry ashing, followed by ion chromatographic detection, was reliable for the determination of total sulphur. Good recoveries were obtained in both reference samples and spiked samples. Total sulphur was 14.5±0.6 g kg⁻¹ relative to dry sediment. Wet chemical methods that involve the determination of acid-volatile, Zn–HCl-reducible, chromium-reducible, acetone-soluble and HI-reducible sulphur were used to estimate specific sulphur forms. Results for acetone-soluble sulphur were to high and not consistent with results for other fractions. Major part of sulphur in the sediment (90%) was inorganic. Sulphides were converted partially to sulphate and to intermediary oxidised sulphur compounds upon oxidation of the sediment. The results suggested that the intermediary oxidised sulphur pool in the reduced sediment (2.5 g kg⁻¹) mainly consisted of pyrite, that was not converted during drying and oxidation. No significant changes in organic sulphur were detected.     

分散法制备的CuCl/MCM-41上C3H6选择催化还原NO反应的研究

研究了由分散法制备的两种CuCl/MCM-41催化剂上丙烯在过量氧存在下选择催化还原NO反应, 发现所制备的CuCl/AlMCM-41催化剂的反应活性明显高于CuCl/SiMCM-41. XRD, IR, TPR及ESR的研究结果表明, CuCl/AlMCM-41催化剂上的主要活性中心是与骨架铝配位的铜离子(Cu2+/Cu+).     

芳香族化合物的脱芳构化反应

芳香族化合物稳定、易得，通过芳香族化合物的脱芳构化反应，制备官能化的脂肪六元碳环化合物，早以引起人们的广泛兴趣。本文对六类脱芳构化反应进行了逐一评述，其包括：氧化脱芳构化反应；还原脱芳构化反应；光催化脱芳构化反应；亲核加成脱芳构化反应；σ-键迁移重排脱芳构化反应；过渡金属参与的脱芳构化反应。其中，过渡金属参与的脱芳构化反应，反应条件温和，反应底物广泛，可应用于生物活性物质的合成。     

Aktivierung von CO2 an Übergangsmetallzentren: Zum Ablauf der CO2-Reduktion an Nickel(0)-Fragmenten

Activation of CO₂ at Transition Metal Centres: The Route of the CO₂ Reduction at Nikel(0) Moieties A competing reaction in the catalytic cyclooligomerization of hex-3-yne and CO₂ at the (TMED)Ni(0)-fragment (TMED = N,N,N′,N′-tetramethylethylendiamine) is the formation of carbon monoxide and (TMED)Ni(CO₃). So it is possible to explain the generation of II (TMED)Ni(diethylmalicacidanhydride) and III (a nickel trimer with two (TMED)Ni(CO₃) units). Both complexes are characterized by X-ray analysis. The reduction of CO₂ to CO most likely proceeds via an intermediate in which two molecules of carbon dioxide are coupled head-to-tail to form a metallacycle. An ab initio scf geometry optimization supports the existence of such an intermediate.     

Promoting effect of sol-gel method and pre-treatment on the activity of SnO2/Al2O3 catalyst for NO reduction by propene

SnO₂/Al₂O₃ catalyst prepared by sol-gel method showed higher activity than those prepared by impregnation method, and their activity was significantly improved by pre-treatment in the reaction gas. The increased activity is closely related to the agglomeration of SnO₂ species and the re-exposure of Al₂O₃, which was previously covered by dispersed SnO₂ species. This revised version was published online in June 2006 with corrections to the Cover Date.     

甲烷氧化细菌催化二氧化碳生物合成甲醇的研究

甲烷氧化细菌中包含的甲烷单加氧酶(MMO)、甲醇脱氢酶(ADH)、甲醛脱氢酶(FaldDH)、甲酸脱氢酶(FateDH)经过一系列反应能够把甲烷深度氧化生成二氧化碳，并生成一定的能量物质．把二氧化碳还原为甲醇是一个需要能量的过程，目前还没有已知的有机体在温和条件下完成这一反应．研究发现，甲基弯菌Methylosi-nus trichosporium IMV 3011可以催化二氧化碳生物转化生成甲醇．在休眠的悬浮细胞中充人二氧化碳后，反应一段时间在反应液中检测到了甲醇．二氧化碳转化成甲醇是一个需要能量推动的反应，为了补充反应所消耗的能量．反应一段时间后需要用甲烷进行再生，以恢复细胞中的还原当量NADH．我们进行了反应再生的交替连续批式反应，甲醇积累量能够维持在一个比较稳定的水平．理论上，反应不会增加温室效应，这是一个有效的、环境友好的、可恢复的反应过程．     

菲的电解还原

菲的电解还原胡明，刘旭光，王志忠（太原工业大学，太原０３００２４）关键词菲，有机电化学，电解还原近年来有机电解技术引入煤转化领域的研究已有过一些综述￣［１～６］。以多环芳烃为模型化合物，研究其在电解条件下的转化行为，从理论和实践上都将为煤及其加工产品...     

Inorganic electrides

Inorganic electrides are a novel kind of ionic compounds in which the anions are electrons confined in a complex array of cavities or channels and the cations are nanoscale arrays of alkali metal ions that provide charge balance. In electrides the donated electron behaves like a low-density correlated electron gas, whereby the dimensionality of the electron gas and its electronic and magnetic properties are determined by the topology of the cavities in the host matrix. Unlike traditional electrides, in which alkali cations are encapsulated within an organic cage, inorganic electrides are thermally stable. The current inorganic electrides based on alkali metal loaded zeolites can be designed as useful reduced-dimensionality materials. Inorganic electrides are powerful reducing agents, and they are able to reduce small aromatic molecules to the radical anions within the channels of the zeolite.