Rh-catalyzed carbonylation of arylzinc compounds yielding symmetrical diaryl ketones by the assistance of oxidizing agents

Carbonylative homocoupling of arylzinc compounds 1 using 1 atm of CO and 1,2-dibromoethane as an oxidant was achieved in the presence of Rh-dppf catalyst, affording symmetrical diaryl ketones in good yields. Under similar conditions, Pd or Ni catalysts induced oxidative homocoupling of 1 to yield biaryls instead. The beneficial catalysis by Rh in the carbonylation was presumed to stem from the facility by which the migration of the aryl ligand to CO at the Rh(3+) intermediate occurred.     

地基多轴DOAS仪器的NO2斜柱浓度对比研究

介绍了两台地基多轴DOAS仪器测量的NO2斜柱浓度的对比研究。利用日本海洋研究开发机构的一套多轴DOAS设备在2009年11月—12月31日期间16d的观测数据,与安光所自主研发的一套多轴DOAS设备测量的NO2差分斜柱浓度进行了对比。通过对比发现,采用自动调整积分时间的方法,与固定积分时间的设置相比仪器具有更高的信噪比;两套仪器的反演结果在小角度下具有比较好的一致性,相关系数高达0.995,但随着角度的增大相关性逐渐变差。在9点至16点时段内相对偏差较小,其中20°方向的结果最为接近,最小偏差仅有12%,但在9点前和16点后二者偏差增大。日方仪器在可见波段的反演结果明显好于紫外波段,反演中的剩余噪声减小了60%以上,同时在可见波段的差分斜柱浓度的计算结果与我们的多轴DOAS在紫外波段的计算结果在全天都具有非常好的一致性。     

Direct separation of regio- and enantiomeric isomers of diacylglycerols by a tandem column high-performance liquid chromatography

A novel HPLC-based method for direct separation of the three isomers of mono-acid diacylglycerols (DAGs), i.e., 1,2-DAG, 2,3-DAG and 1,3-DAG, has been established. The method employs a tandem column system, in which two different columns (a conventional silica gel column and a chiral stationary phase column) are connected in series. Two isomeric mixtures of DAGs (i.e., dicapryloylglycerol and dioleoylglycerol) and lipase-catalyzed reaction mixtures were successfully resolved on the tandem column HPLC system without any derivatization prior to the analysis. According to the established analytical method, stereoselectivity of two lipases toward mono-acid triacylglycerols in ethanolysis reaction was investigated. The tested enzymes were immobilized Candida antarctica lipase B (CALB) and Rhizomucor miehei lipase (RML). Analyses of the enantiomeric purity of 1,2-DAG and 2,3-DAG, generated as intermediates during the reaction, revealed that CALB and RML have sn-3 and sn-1 stereopreference, respectively.     

Automated odor-sensing system based on plural semiconductor gas sensors and computerized pattern recognition techniques

Although odor is an inherent characteristic of chemical substances, no methods to measure or identify odor objectively have been available. A computerized method for classification and identification of odor is reported. Odors are detected by using eight semiconductor gas-sensor elements which have different sensing properties for gases; the output from the odor-detecting apparatus for a gas sample is represented by an 8-dimensional vector. The vectors for 30 substances were examined by clustering analysis and four obvious clusters were observed. These clusters corresponded to ethereal, etherealminty, ethereal-pungent and pungent substances.     

Metabolomics approach for determining growth-specific metabolites based on Fourier transform ion cyclotron resonance mass spectrometry

Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR/MS) is the best MS technology for obtaining exact mass measurements owing to its great resolution and accuracy, and several outstanding FT-ICR/MS-based metabolomics approaches have been reported. A reliable annotation scheme is needed to deal with direct-infusion FT-ICR/MS metabolic profiling. Correlation analyses can help us not only uncover relations between the ions but also annotate the ions originated from identical metabolites (metabolite derivative ions). In the present study, we propose a procedure for metabolite annotation on direct-infusion FT-ICR/MS by taking into consideration the classification of metabolite-derived ions using correlation analyses. Integrated analysis based on information of isotope relations, fragmentation patterns by MS/MS analysis, co-occurring metabolites, and database searches (KNApSAcK and KEGG) can make it possible to annotate ions as metabolites and estimate cellular conditions based on metabolite composition. A total of 220 detected ions were classified into 174 metabolite derivative groups and 72 ions were assigned to candidate metabolites in the present work. Finally, metabolic profiling has been able to distinguish between the growth stages with the aid of PCA. The constructed model using PLS regression for OD₆₀₀ values as a function of metabolic profiles is very useful for identifying to what degree the ions contribute to the growth stages. Ten phospholipids which largely influence the constructed model are highly abundant in the cells. Our analyses reveal that global modification of those phospholipids occurs as E. coli enters the stationary phase. Thus, the integrated approach involving correlation analyses, metabolic profiling, and database searching is efficient for high-throughput metabolomics. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Facile synthesis of polymers bearing cyclic carbonate structure through radical solution and precipitation polymerizations accompanied by concurrent carbon dioxide fixation

The radical polymerization of glycidyl methacrylate (GMA) was conducted under a carbon dioxide atmosphere (1 atm) in the presence of catalysts for the reaction of carbon dioxide and the oxirane group to afford the five‐membered cyclic carbonate group. The degrees of the carbon dioxide fixation depended on catalysts, concentration, and solvents. In solution reaction, the slower polymerizations resulted in faster carbon dioxide fixation, due to the faster carbon dioxide fixation to GMA than to oxirane moieties in polymers. When the polymerization was conducted in 1,4‐dioxane, which is a good solvent for polyGMA but a poor solvent for the analogous polymer bearing cyclic carbonate moieties, the resulting polymers were precipitated out as the progress of the polymerization and the carbon dioxide fixation. As a result, polymers could be isolated by simple filtration and rinsing with methanol. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3170–3176, 2009