Studies on the Carbon Zip Reaction of 2-Oxocycloalkane-1-carbonitriles

As a part of continuing interest in the zip reaction, we present the results on a carbon ring-enlargement reaction of activated ketones with a CN group as a charge stabilizer. Two series of (1-cyano-2-oxocy-cloalkyl)alkanoates were prepared from 8- and 12-membered cyano-ketones 1 and 2 , respectively, namely the propanoates 3 and 4 , the butanoates 6 , 8 and 9 as well as the pentanoates 12 and 15 . While treatment with t-BuOK of the former two homologous esters resulted in both ring enlargement and competitive transesterification, the pentanoates 12 and 15 afforded mostly the diastereoisomeric mixtures of bicyclic alcohols 20a – c and 31a , b , respectively, which remained intact on further exposure to base. It was shown that – apart from the base used (t-BuOK) vs. Li(i-Pr)₂N – the distribution of products was greatly influenced by the ring size of substrates. This is further illustrated by treatment of ketones 34 and 35 with t-BuOK. While the former rearranged smoothly to diketone 36 , no reaction at all took place with the latter. The behavior of the substrates is discussed in terms of steric and energetic reasons.     

Supercritical Fenton Oxidation: A New Method for Total Organic Carbon Measurement

A new method for total organic carbon (TOC) measurement was established based on supercritical Fenton oxidation. The organic pollutants in wastewater were oxidized to carbon dioxide in supercritical water by Fenton reagents that was detected using a nondispersive infrared detector. The influence of temperature from 380 to 480°C, oxidant coefficient from 1 to 20, pH from 2.2 to 5.2, and Fe²⁺ concentration from 0.2 to 0.8?mg?L^?1 was characterized; the optimal conditions were at 420°C, an oxidant coefficient n?≥?5, a pH of 4.4, and Fe²⁺ concentration of 0.8?mg?L^?1. Using these parameters, the recovery of potassium hydrogen phthalate exceeded 98.2%. The introduction of Fenton oxidation based on supercritical water lowered the temperature and reduced the oxidant coefficient required for TOC determination.     

A New Method for the Production of Carbon Nanotubes

It was found for the first time that carbon nanotubes are formed during the mechanical treatment of V₂O₅ powder in the presence of an organic solvent. The carbon content in the V₂O₅ sample, dispersed in alcohol, varies during milling and amounts to 2.1 wt.%. The unusually large increase in the catalytic activity of mechanically activated V₂O₅ in the selective oxidation of n-butane and also of benzene and propane is due to the formation of new active centers containing carbon inserted into the V₂O₅ structure.     

纳米碳纤维负载钯催化剂在Heck反应中的应用——载体相互作用的影响

使用多元醇还原法制备了均匀分散的钯纳米颗粒.将钯纳米颗粒负载于板式、鱼骨式和管式纳米碳纤维,得到稳定、可重复使用的非均相催化剂.实验结果表明,钯纳米胶粒同载体之间的电位差对钯在载体上的负载量、粒子大小以及Heck反应中钯的溶失量有很大的影响.在制备过程中,增加钯纳米胶粒同纳米碳纤维表面的电位差能够大大降低钯在Heck反应中的流失.催化剂的反应活性随钯粒子的增大而降低.     

再生碳纤维电极的新方法

本文根据火焰熔融法自制碳纤维电极的特点,提出了一种简便、易行的火焰灼烧再生电极的新方法。由此法再生电极的各种性能与原电极相当,结果令人满意。     

Microwave Assisted Intramolecular Wittig Reaction: A Facile Method for the Synthesis of Conjugated Acetylenes

Abstract

A rapid and efficient synthesis of acetylenic compounds by the microwave assisted intramolecular Wittig reaction of β-oxo-alkylidene-triphenylphosphoranes is reported.

     

手性环丙烯构建策略用于对映选择性合成偕二氟亚甲基三元环化合物

作为最小的不饱和环状分子,环丙烯独特的刚性结构和多变的反应活性吸引了化学家的研究兴趣.自1922年Demjanov[1]报道了环丙烯化合物的首例合成以来,现已发展了一系列环丙烯的合成方法.手性环丙烯的合成是通过炔烃和重氮化合物的[2+1]不对称环加成反应.根据底物的不同,这些不对称环加成反应可以分为四类:(a)末端炔烃和单取代重氮化合物的反应,(b)末端炔烃和双取代重氮化合物的反应,(c)非末端炔烃和双取代重氮化合物的反应,(d)非末端炔烃和单取代重氮化合物的反应.在这四类反应中,末端炔烃和单取代重氮化合物的不对称反应相对容易进行.1992年,Doyle和Müller等[2]报道了手性铑催化剂[Rh2(5R-MEPY)4]促进的末端炔烃和重氮醋酸酯之间的不对称环丙烯基化反应(Scheme 1a).随后各种手性催化剂包括[Rh2(OAc)-(DPTI)3][3]、Ir(salen)衍生物[4]和[Co(3,5-diMes-Chen-Phyrin)][5]等被先后报道用于末端炔烃和单取代重氮化合物的不对称[2+1]环加成反应.     

The Reimer-Tiemann Reaction in Slightly Hydrated Solid-liquid Medium: A New Method for the Synthesis of Formyl and Diformyl Phenols

Formylation of phenol in weakly hydrated heterogeneous solid-liquid medium makes it possible to transform phenol into salicyl-aldehyde and parahydroxybenzaldehyde with a ratio of 4.5/1 with excellent yield. Use of methanol as cosolvent modifies the orientation of this reaction, which leads for the first time to simultaneous synthesis of salicyladehyde and parahydroxybenzaldehyde, of 2-hydroxy 1,3-benzenedicarboxaldehyde, and of 2-hydroxy 1,3-benzenedicarbox-aldehyde. Experimental conditions make it possible to easily extract each of these molecules.     

一种增加SOFC阳极三相反应区的方法

近年来 ,固体氧化物燃料电池 ( SOFC)以其高效、低污染的特性 ,越来越受到国内外的普遍重视 .SOFC由阴极、阳极和夹在其间的电解质组成 ,其中阳极性能的优劣对整个电池的性能有着相当大的影响 .目前 ,传统的阳极材料大都选用 Ni+ YSZ[1～ 4 ] .Murray等 [5] 最近报道了在阳极与电解质之间附加一层具有混合导电性能 (同时具有较高的离子导电率和电子导电率 )的 YDC( 1 5% Y2 O3+ 85%Ce O2 )后 ,可大大降低阳极与电解质之间的界面阻抗 ,增加三相反应区和氧离子流通 ,从而提高电池的输出功率 .我们认为 ,如果能以掺杂的复合阳极代替附…     

A Novel Thermooptical Detection Method for Enzyme Reaction Based on the Optical Beam Deflection Induced by Reaction Heat

A novel thermooptical detection method for enzyme reaction based on the optical beam deflection induced by reaction heat is proposed. A probe beam passes through a CCl₄ phase above which a model enzyme reaction occurs. The enzyme reaction medium is arranged to be either interfaced directly with the CCl₄ phase or separated from the CCl₄ phase by a thin gold film. The decomposition reaction of hydrogen peroxide catalyzed by catalase is used as a model enzyme reaction. In the arrangement that the reaction medium is interfaced directly with the CCl₄ phase, both the reaction heat and the reaction product O₂ diffuse into the CCl₄ phase, and thus generate temperature and concentration gradients, respectively. Since both the temperature and concentration gradients induce the deflections of the probe beam, two peaks are observed in the deflection signal. On the other hand, in the arrangement that the reaction medium is separated from the CCl₄ phase by the gold film, only the deflection signal generated by the temperature gradient is detected. The quantitative relations between the deflection signals induced by the reaction heat and the concentrations of catalase and H₂O₂ are investigated. Under the present batch experimental conditions, deflection signals are linear in the concentration ranges of 4 × 10⁻³-4 × 10⁻² mol/liter for H₂O₂, and 11-550 μg/ml (activity, 11-550 unit/ml) for catalase solution, respectively. The detection limits for H₂O₂ and catalase solution are 4 × 10⁻³ mol/liter and 11 μg/ml (activity, 11 unit/ml), respectively. In addition, the possibilities of development as a new thermooptical biosensor and application to the determination of activity distribution of this method are also discussed.     

A New Method for the Characterization of Organic Carbon in Aquatic Systems

Abstract

Some problems in organic carbon characterization are briefly discussed. A new chromatographic multi-method for the direct characterization of organic matter in original waters with the simultaneous determination of UV-Vis, fluorescence, DOC, TIC, and organically bound nitrogen (DON) is described. Some applications with UV-Vis and DOC (“CODOC”) detection are presented.     

The Reaction of 1,3-Disubstituted Benzimidazolium Salts With Grignard Reagents and A Novel Synthetic Method for Aldehydes

Aliphatic and aromatic Grignard reagents have been found to add to the double bond of 1, 3-disubstituted benzimidazolium salts. The resulting substituted benzimidazolines were hydrolyzed and the aldehydes converted directly to their 2, 4-dinitrophenylhydrazone derivatives. The scope and limitations of this synthesis are discussed.     

Novel Synthetic Method for Piperitenones Through Diels-Alder Reaction

The Diels-Alder adduct obtained from 1-(2-phenyl-selenoethoxy)isoprene and methyl vinyl ketone was applied to synthesis of piperitenones.     

非水库仑滴定法测定碳

1引言碳（碳酸盐）的测定曾做过广泛研究,其中,非水库仑滴定测碳因其滴定效率高,稳定性好被列入ＡＳＴＭＤ－５１３－８２;该方法推荐使用美国库仑公司的专利仪器及电解液,其关键技术是非水电解液。本文对该方法的电解液进行了组分选择及优化,建立起完整的测定装置,取得了较好的结果;可作为测定金属含碳量、水体中溶解无机碳的首选方法,广泛应用于冶金、环保等领域。2实验部分2．１仪器与试剂ＫＬＴ－１型库仑仪（江苏电分析仪器厂）;ＰＨＳ－２型酸度毫伏计（上海雷磁仪器厂）。试剂：二甲亚砜、乙醇胺、四乙墓滨化胺为分析纯;…