Zinc(II) Homogeneous and Heterogeneous Species and Their Application for the Ring‐Opening Polymerisation of
<i>rac</i>
‐Lactide
作者:Matthew D. Jones、Matthew G. Davidson、Callum G. Keir、Laura M. Hughes、Mary F. Mahon、David C. Apperley
DOI:10.1002/ejic.200801049
日期:2009.2
motif was detected. The Schiff base ligand L1H was anchored to silica and treated with Zn(OAc)2·2H2O to form the heterogeneous ZnII system. This was characterised by 13C1H} CP/MAS NMR spectroscopy. All homogeneous and heterogeneous catalysts were assessed for the ring-opening polymerisation of rac-lactide at 130 °C in the absence of solvent, using unsublimed monomer. All catalysts offered good conversions
Methyltrioxorhenium-catalyzed oxidation of pseudocumene for vitamin E synthesis: A study of solvent and ligand effects
作者:Mónica Carril、Philipp Altmann、Markus Drees、Werner Bonrath、Thomas Netscher、Jan Schütz、Fritz E. Kühn
DOI:10.1016/j.jcat.2011.07.003
日期:2011.10
VitaminE is an essential food component of major economical relevance with important antioxidant properties and biological activity. The oxidation of pseudocumene to trimethyl-1,4-benzoquinone would be a key transformation in an alternative industrial production of α-tocopherol that is important for the antioxidant activity of vitaminE. The methyltrioxorhenium (MTO)-catalyzed oxidation of pseudocumene
Multicomponent Cascade Reactions for the Synthesis of 2,3-Dihydrobenzofuran Derivatives
作者:Qu-Bo Li、Xiao-Chun Hu
DOI:10.1246/cl.2012.1633
日期:2012.12.5
A multicomponentcascadereaction for the synthesis of highly substituted 2,3-dihydrobenzofuran derivatives with moderate to good yields was developed. The synthetic utilities of these 2,3-dihydrob...
Fourteen new phenoxy-azo aluminiumcomplexes comprising two series, namely, dimethylphenoxy-azo}aluminiumcomplexes 1a–7a and monomethylphenoxy-azo}aluminiumcomplexes 1b–7b, were successfully synthesised and characterised. The molecular structure of complex 4a, determined using X-ray diffraction analysis, displayed a distorted tetrahedral geometry. The 1H NMR spectrum of complex 5b revealed fluxional
成功合成并表征了包含两个系列的14种新型苯氧基偶氮铝配合物,即二甲基苯氧基偶氮}铝配合物1a-7a和单甲基苯氧基偶氮}铝配合物1b-7b 。使用X射线衍射分析确定的配合物4a的分子结构显示出扭曲的四面体几何形状。配合物5b的1 H NMR 谱揭示了室温下溶液中发生的异构体转变引起的通量行为。甲苯-d 8中变温1 H NMR 谱线形分析确定的活化参数如下: Δ H ‡ = 70.05 ± 1.19 kJ mol −1 , Δ S ‡ = 21.78 ± 3.58 J mol −1 K −1 ΔG ‡ (298 K) = 63.56 ± 0.11 kJ mol −1 。所有铝配合物都是外消旋丙交酯开环聚合的活性引发剂,并且聚合以受控方式进行并且是活性的。相比之下,二甲基苯氧基-偶氮}铝配合物的催化活性与相应的单甲基苯氧基-偶氮}铝配合物的催化活性没有显着差异。观察到邻苯氧基取代基的空间因子对催化速率产生减速作用。