磺酸树脂Amberlyst70催化环己酮肟液相重排制己内酰胺

实验以大孔氢型耐高温磺酸树脂Amberlyst 70为催化剂,环己酮肟液相重排制已内酰胺.考察了反应温度、反应时间、催化剂用量等因素对重排反应的影响.实验结果表明:常压下、温度为130℃、m(环己酮肟):m(催化剂)=1.13:1,反应6h,环己酮肟转化率可达99.4％,己内酰胺的选择性可达90.2％.该催化剂催化效率...     

The evolution of poly(hydroxyamide amic acid) to poly(benzoxazole) via stepwise thermal cyclization: Structural changes and gas transport properties

The thermally induced structure transformation and polymer chain rearrangement of a thermally rearranged (TR) material for gas separation has been explored in this work. A tremendous enhancement as high as 215 folds in CO₂ permeability has been achieved by converting the pristine poly(hydroxyamide amic acid) (PHAA) to the final polybenzoxazole (PBO) via thermal cyclization at 400 °C for 2 h. The evolution of the pristine polymer PHAA derived from 2,2-bis(3-amino-4-hydroxyphenyl)hexafluropropane (BisAPAF) and trimellitic anhydride chloride (TAC) by thermal treatment from 130 °C to 400 °C has been examined by various characterization techniques including elemental analysis, TGA, TGA-IR, DSC, ATR-FTIR, XPS, XRD and Positron Annihilation Lifetime Spectroscopy (PALS). The stepwise cyclization process commences with cyclodehydration followed by cyclodecarboxylation. At the first step, PHAA transforms to poly(imide benzoxazole) (PIBO) up to 300 °C, while at the second step, the final structure of PBO is formed at 400 °C. Following the changes in the cyclization process, gas transport properties also show the stepwise changes. The significant enlargements of polymer inter-chain distance and free volume cavity radius provide the fundamental understanding for the changes of gas transport properties at the molecular level.     

Gold Catalysis: β‐Ketonaphthalenes via Molecular Gymnastics of 1,6‐Diyne‐4‐en‐3‐ols

1,6‐Diyne‐4‐en‐3‐ols with one terminal alkyne were applied as test substrates for a possible dual catalyzed cyclization. Instead of a dual catalysis cycle, naphthyl ketone derivatives were obtained as single products. The regioselectivity of the obtained products is unprecedented. Instead of the expected naphthyl ketones bearing the keto group in the α‐position, the keto group is positioned in the ß‐position of the naphthyl skeleton by a complex rearrangement of the starting materials.     

Cyanide‐Catalyzed Additions of Acyl Phosphonates to Aldehydes: A New Acyl Donor for Benzoin‐Type Reactions

Acyl phosphonates have been utilized as new acyl donors for cyanide‐catalyzed benzoin‐type reactions. Cyanation of acyl phosphonates, followed by a [1,2]‐phosphoryl migration generates the active acyl anion intermediate. The presumed (cyano)phosphate anion reacts with a variety of aryl aldehydes to yield phosphate ester‐protected, unsymmetrical benzoins in good to excellent yields. The unsymmetrical benzoin product can be obtained after deprotection of the phosphate ester with an aqueous amine solution.     

Gold‐Catalyzed Efficient Formation of α,β‐Unsaturated Ketones from Propargylic Acetates

An efficient gold‐catalyzed method for the preparation of α,β‐unsaturated ketones from propargylic acetates has been developed. Under mild reaction conditions, β‐monosubstituted enones were formed mostly with excellent E‐selectivity. β,β‐Disubstituted enones can be prepared from propargylic acetates derived from ketones. The high efficiency and mild nature of this reaction render it a viable alternative for the synthesis of α,β‐unsaturated ketones.     

集中控制与分布式智能相结合的故障后网络重构方案

在现场自动化装置中使用分布式智能的控制方案,可不依赖于通信和主站计算机系统而独立工作,达到隔离故障、转移和恢复供电的目的,与一般的就地控制方案比,开关操作次数少、时间短.在有良好的通信系统场合,控制方案自动升级,可以更高效率地进行故障后的网络重构.当有完善的主站、子站系统进行集中模式控制时,分布式智能可作为其后备方案,使自动化系统更加可靠.     

Issues in the Reconstruction of Gene Order Evolution

As genomes evolve over hundreds of millions years, the chromosomes become rearranged, with segments of some chromosomes inverted, while other chromosomes reciprocally exchange chunks from their ends. These rearrangements lead to the scrambling of the elements of one genome with respect to another descended from a common ancestor. Multidisciplinary work undertakes to mathematically model these processes and to develop statistical analyses and mathematical algorithms to understand the scrambling in the chromo...     

Photo-induced aminobenzoate group formation on a polymeric photobase generator bearing N-phenylcarbamate groups and its application to color imaging material

A polymeric photobase generator bearing N-phenylcarbamate groups was prepared to generate aromatic amino groups upon irradiation and used for color imaging on a thin polymer film. Polymer bearing N-phenylcarbamate groups was prepared by copolymerization of methacryloyloxyethyl phenylcarbamate (MPC) and methyl methacrylate (MMA). The photochemical process of the polymer was monitored through the UV and IR absorption spectral analyses and contact angle measurements. Irradiation of the polymer led to the formation of aminobenzoate groups through the photo-Fries type rearrangement or cross-linking through the radical coupling reaction of N-phenylcarbamate groups. The cosinus values of contact angle (θ) of the polymer film decreased upon irradiation indicating that the polymer surface developed a hydrophobic property. A color image was produced by a diazocoupling reaction of the aminobenzoate groups which were produced in the irradiated area of the polymer film with phenolic or aromatic amino coupling agent. The yellow color was developed by resorcinol or aniline treatment, whereas the red color was produced by the naphthol AS or 1-naphthylamine treatment.     

重排反应在精细化工中间体合成中的应用

因为在有机合成中有些反应通过常规的合成法难以达到预期的目的或比较烦琐,因此重排反应是一个行之有效的方法。重排反应具有很高的反应效率,而且具有很高的立体选择性。本文主要阐述了重排反应在医药、农药、天然产物、染料等合成中的应用。