Efficient preparation of highly substituted thiophenes and thiophene-based arylacetic acids

An efficient and one-step method for the preparation of highly substituted thiophenes and thiophen-2-yl-acetic acid derivatives was developed. Hence, thioacetomorpholides were smoothly reacted with α-bromo carbonyl compounds in [bmim]OH as an efficient dual catalyst-reaction medium to produce the title compounds in good yields.     

两个新型联芳化合物的合成与表征

采用苯乙腈为原料，经硝化、还原等步骤，合成芳胺4－氨基苯乙腈和3－硝基－4－氨基苯乙腈，以此二芳胺为反应底物，在三氯乙酸、铜粉、TBAB、亚硝酸戊酯存在下与噻吩发生偶联反应合成新型联芳化合物，3－硝基－4－（2－噻吩基）苯乙脯和4－（2－噻吩基）苯乙腈，最终产物的结合经IR、^1HNMR、MS元素分析而确证。     

Effect of SWNT Defects on the Electron Transfer Properties in P3HT/SWNT Hybrid Materials

Poly(3‐hexylthiophene) (P3HT) hybrids with single‐walled carbon nanotubes (SWNTs) were prepared using a series of SWNTs with various defect contents on their surfaces. The hybrids were synthesized by exploiting the π–π interaction between P3HT and the SWNTs, resulting in efficient dispersion of the carbon nanotubes in the P3HT solution. UV‐visible and photoluminescence (PL) spectra showed that the carbon nanotubes quench the PL of P3HT in the hybrids, indicating that electron transfer occurs from photo‐excited P3HT to the SWNTs. This electron transfer from P3HT to carbon nanotubes was disrupted by the presence of defects on the SWNT surfaces. However, the PL lifetime of P3HT in the hybrids was found to be the same as that of pure P3HT in solution, indicating the formation of a ground‐state non‐fluorescent complex of P3HT/SWNTs.     

The Use of Copper Immobilized on Silica for Compound Class Fractionation of Polycyclic Aromatic Compounds in Environmental Samples

Abstract

Copper immobilized on silica has been investigated as an adsorbent for the fractionation of polycyclic aromatic compounds (PACs) into different compound classes. an open column chromatographic packing based on copper (II) bound to a silica substrate was used as a means of subdividing the PACs into less complex groups of similar compound types. the process has been applied to the fractionation of PACs extracted from a marine harbour sediment, for which the complex mixture of PACs could be separated into three subgroups, the contents of which were: (1) polycyclic aromatic hydrocarbons (PAHs), alkylated PAHs, and thiophenes; (2) compounds containing pyrrole-type (sp ³-hybridized) nitrogen (carbazoles), and also quinones and other oxygen containing species; and (3) compounds containing pyridine-type(sp ²-hybridized) nitrogen (acridine and its homologues). the fractions thus obtained have been characterized by gas chromatography-mass spectrometry (GC-MS). Extracted mass spectra, obtained from the crests of GC-MS peaks observed in reconstructed single ion chromatograms of selected m/z values, enabled unambiguous identification of many of the minor components of the mixture.     

Thiophene occurrence in different Tagetes species: agricultural biomasses as sources of biocidal substances

BACKGROUND: Tagetes species produce thiophenes, polyacetylenic compounds that possess strong biocidal activity, thus making Tagetes plants very useful for suppressing nematode populations in the soil and as sources of natural pesticides. In the present study, Tagetes species (T. erecta, T. filifolia, T. lucida, T. minuta, T. patula and T. tenuifolia) grown in northern Italy were evaluated for their morphophenological parameters and thiophene pattern in different plant parts (roots, shoots and flowers). RESULTS: Roots had the highest diversity and contents of thiophenes (from 64 to 100% of the total thiophene amount), with 5‐(3‐buten‐1‐ynyl)‐2,2′‐bithienyl (BBT) as the main component followed by 5‐(4‐acetoxy‐1‐butynyl)‐2,2′‐bithienyl (BBTOAc), 2,2′:5′,2″‐terthienyl (α‐T) and 5‐(4‐hydroxy‐1‐butynyl)‐2,2′‐bithienyl (BBTOH). Tagetes lucida and T. tenuifolia possessed the highest amounts of total thiophenes (6717.3 and 6452.5 mg kg^?1 dry weight respectively), while T. minuta had the highest total thiophene yield (518.8 mg m^?2), with BBT accounting for 98% of the total. CONCLUSION: Considering both thiophene concentrations and biomass yields, T. minuta and T. lucida appeared to be the most promising Tagetes species, with high potential for use as biocidal crops for the implementation of pest control practices that are less harmful to human health and natural resources. Copyright © 2010 Society of Chemical Industry     

A Highly Practical and Reliable Nickel Catalyst for Suzuki–Miyaura Coupling of Aryl Halides

We disclose that [1,3‐bis(diphenylphosphino)methane]nickel(II) chloride [NiCl₂(dppp)] is a highly active, universally applicable, cheap, and stable catalyst for Suzuki–Miyaura cross‐coupling reactions of aryl halides with a catalyst loading of lower than 1 mol%, and more notably, in the absence of extra supporting ligands. Under the optimized reaction conditions, a broad range of aryl bromides as well as the notoriously unreactive aryl chlorides, including activated, non‐activated, deactivated, and heteroaromatic and sterically hindered substrates can be coupled smoothly with various boronic acids (47 examples, 48–98% yields). In addition, the transformation is tolerant of various functional groups such as ether, ester, ketone, aldehyde, cyano, and unprotected amino and hydroxy groups. Finally, the potential utilization of the methodology was further demonstrated by the gram‐scale synthesis of several core structures of commercialized antihypertensive drugs and fungicides. Thus, the combination of high activity, broad applicability, cheapness, and high stability of NiCl₂(dppp) presented in this work constitutes one of the few prominent catalysts which allow for practical and reliable construction of biaryls and heterobiaryls with structural diversity from readily available aryl halides and boronic acids.