A new series of poly(hydrazone–ether)s was synthesized from 3,4-dimethylthieno [2,3-b] thiophene-2, 5-dicarbohydrazide, II and 4,4′-diformyl-α, ω-diphenoxyalkanes or 4,4′-diformyl -2,2′-dimethoxy -α, ω-diphenoxyalkanes. The inherent viscosities of the polymers were in the range 0.22 – 0.56 dIg?1. Majority of the polymers were soluble in concentrated H2SO4. Their thermotropic liquid crystalline properties were examined by DSC, an optical polarizing microscopy using a hot stage and thermogravimetric analyses. The polymers exhibited almost thermotropic liquid crystalline properties. In most cases, the mesophases extended up to 430°C, where thermal decomposition prevented further observation.
It is a pleasure to acknowledge Dr M. Abd El-Moniem at Geology Department, Faculty of Science, Assiut University, for his assistance in the measurements of optical properties. 相似文献
Abstract Pseudo‐hydroxide extraction of sodium hydroxide from aqueous solution using four alkyl phenols of nearly identical molecular weight in 1‐octanol at 25°C was examined to understand the effect of alkyl substituents. The order of extraction strength among the four alkyl phenols tested was 4‐tert‐octylphenol>3,5‐di‐tert‐butylphenol>2,4‐di‐tert‐butylphenol>2,6‐di‐tert‐butyl‐4‐methylphenol. A good correlation with phenol pKa was observed, indicating that extraction strength is determined by phenol acidity, as modified by steric effects in proximity to the phenol –OH group. The effective partition ratios (Peff) of two phenols from 1 M NaOH solution were determined, showing that the phenols remain predominantly in the 1‐octanol phase even when converted to their sodium salts. However, the hydrophobicity of the tested phenols may not be sufficient for process purposes. The equilibrium constants for the governing extraction equilibria were determined by modeling the data using the program SXLSQI, supporting the cation‐exchange extraction mechanism. The proposed mechanism consists of two simple sets of equilibria for
Ion‐pair extraction to give Na+OH? ion pairs and corresponding free ions in 1‐octanol the phase and
Cation exchange by monomeric phenol molecules (HAs) to form monomeric organic‐phase Na+A? ion pairs and corresponding free organic‐phase ions.
This research was sponsored by the Environmental Management Science Program, Office of Science, U.S. Department of Energy, under contract DE‐AC05‐00OR22725 with Oak Ridge National Laboratory, managed and operated by UT‐Battelle, LLC. Support for H.‐A.K. under the Postdoctoral Fellowship Program of Korea Science & Engineering Foundation (KOSEF) is gratefully acknowledged; the participation of H.‐A.K. was made possible by an appointment to the Oak Ridge National Laboratory Postgraduate Program administered by the Oak Ridge Associated Universities. The authors thank Peter V. Bonnesen and Nancy L. Engle for providing compounds and Lætitia H. Delmau and Tamara J. Haverlock for providing assistance with experiments and data manipulation. Thanks are also extended to Dr. Reza T. Dabestani for assistance with UV‐Vis measurements. 相似文献
d-Amino acids are pharmaceutically important building blocks, leading to a great deal of research efforts to develop cost-effective synthetic methods. Preparation of d-amino acids by deracemization has been conceptually attractive owing to facile synthesis of racemic amino acids by Strecker synthesis. Here, we demonstrated biocatalytic deracemization of aliphatic amino acids into d-enantiomers by running cascade reactions; (1) stereoinversion of l-amino acid to a d-form by amino acid dehydrogenase and ω-transaminase and (2) regeneration of NAD+ by NADH oxidase. Under the cascade reaction conditions containing 100 mM isopropylamine and 1 mM NAD+, complete deracemization of 100 mM dl-alanine was achieved after 24 h with 95% reaction yield of d-alanine (>?99% eeD, 52% isolation yield).
A green synthesis of 3-indolyl-3-hydroxy oxindoles was reported using hen egg white lysozyme (HEWL) in an aqueous ethanol. The HEWL promotes this reaction efficiently from various isatins and indoles under mild reaction conditions with yields up to 98% bearing good adaptability to varied substrates in the reaction. This conversion has provided a new strategy to synthesize 3-indolyl-3-hydroxy oxindole derivatives employing biocatalytic promiscuity of less explored lysozyme. Based on the experimental studies, the plausible reaction mechanism is proposed.
A series of new waterborne polyurethanes (WPUs) was successfully prepared by the prepolymer process from the bio-renewable sources hydroxytelechelic natural rubber (HTNR with MW 3000 g mol?1) and hydroxylated rubber seed oil (HRSO), with DMPA fixed at 5.6 wt%. The effects of ratio of HTNR and HRSO (ranging from 1.00/0 to 0.10/0.90) and of hydroxyl value (OHV) of HRSO (200 or 270 mgKOH/g) on final properties were studied. It was found that the particle size of WPU increased significantly with both HRSO/HTNR ratio and OHV of HRSO. Chemical structure of the WPU films was confirmed by FT-IR. The water uptake, mechanical, dynamic mechanical properties and thermal stability of WPU film improved with both HRSO content and OHV of HRSO, while swelling in THF decreased. All these WPU films had similar Tg. This article reports novel green biobased WPU with promising applications as adhesive for shoe industries.
Gas phase dehydration of glycerol formerly in aqueous solution to acrolein was studied over iron MFI zeolites prepared by post-synthesis isomorphous substitution with different iron contents, Si/Al and substitution ratios. High Si/Al (60) ratios led to high conversion in presence of air and the insertion of iron in the zeolite framework greatly improved the catalytic performances by altering the amount and the nature of the coke components reducing dramatically the deactivation. Over the most efficient sample, acrolein yield reached a stabilized value of 68% with an excellent selectivity (80%), which ranked this catalyst among the best for the selective conversion of crude glycerol.
Ternary heterojunctions g-C3N4/ZnS/CuS with different morphologies were constructed. The g-C3N4/ZnS/CuS (hexagonal-nanosheets) exhibited the largest photocurrent, the best photocatalytic and electrochemical activity, which revealed the influence discipline of different morphologies on photoconductivity, photo/electro-catalytic activity. It indicated that this heterojunction can be used as an excellent photoconductor device, a high-efficiency photo/electro-catalyst.
A simple, one-pot, three-component, green synthesis of a wide range of propargylamines is reported by A3-coupling (aldehyde, alkyne and amine) via C–H activation of alkynes using [Zn(l-proline)2] as an efficient and reusable heterogeneous catalyst. High catalytic activity was achieved in comparatively low temperature under solvent-free conditions. All reactions were carried out in an open atmosphere without the use of any co-catalyst/additive.
We have mimicked the biofilm formation with highly stable biocompatible poly(2-methyl-2-oxazoline)-based polymersomes by simple spreading-drying of a droplet of the sample solution onto a glass support. The diffusion-limited aggregation process of polymersomes onto the surface was analyzed within a fractal framework. The different examples analyzed and presented together indicate one means by which the aggregation process can be controlled and predicted. The anti-bacterial adhesion properties of poly(2-methyl-2-oxazoline) allow potential uses in surface modification for biofouling prevention improving stability and response time.
Friedel–Crafts reaction of anisole over high silica mordenite zeolite was investigated. Detailed reaction profiles were obtained using various reaction conditions. In particular, the behavior of acetic anhydride during the reaction and the effect on the hydrophilicity of the mordenite zeolite catalyst were investigated.
