Anisole hydrogenation with well-characterized polyoxoanion- and tetrabutylammonium-stabilized Rh(0) nanoclusters: effects of added water and acid, plus enhanced catalytic rate, lifetime, and partial hydrogenation selectivity

Following a comprehensive look at the arene hydrogenation literature by soluble nanocluster catalysts, six key, unfulfilled goals in nanocluster arene hydrogenation catalysis are identified. To begin to address those six goals, well-characterized polyoxoanion- and tetrabutylammonium-stabilized Rh(0) nanoclusters have been synthesized by the reduction of the precisely defined precatalyst [Bu(4)N](5)Na(3)[(1,5-COD)Rh small middle dotP(2)W(15)Nb(3)O(62)] with H(2) in propylene carbonate solvent. These Rh(0) nanoclusters are characterized by their stoichiometry of formation, transmission electron microscopy, and the two rate constants which characterize their mechanism of formation; previous studies in our laboratories have provided additional characterization of polyoxoanion-stabilized Rh(0) nanoclusters. Propylene carbonate solutions of the Rh(0) nanoclusters catalyze the hydrogenation of anisole (methoxybenzene) under mild conditions (22-78 degrees C, 30-40 psig H(2)). Proton donors such as water or HBF(4) small middle dotEt(2)O are discovered to affect both nanocluster formation and nanocluster arene hydrogenation catalysis. Under identical conditions, the Rh(0) nanoclusters are 10-fold more active than a commercially available, oxide-supported 5% Rh/Al(2)O(3) catalyst of the same average metal-particle size. A series of lifetime experiments shows that the Rh(0) nanoclusters are capable of at least 2600 total turnovers (TTO), a lifetime significantly longer than the approximately 100 TTO often seen for nanocluster arene hydrogenation catalysts, and a lifetime slightly better than the prior record of 2000 TTO for a literature nanocluster system. The present polyoxoanion-stabilized Rh(0) nanoclusters also display a record, albeit modest, 30% selectivity for the partial hydrogenation of anisole to 1-methoxycyclohexene with an overall yield of up to 8% at higher temperatures. In comparison to the 5% Rh/Al(2)O(3) catalyst, the polyoxoanion-stabilized nanoclusters yield a 4.7-fold higher maximum yield of 1-methoxycyclohexene. Finally, the seven main findings of the present work are summarized, including how they address five of the aforementioned six main goals in nanocluster arene hydrogenation.     

高聚合度Ⅱ-型聚磷酸铵的合成

用聚合反应-热处理两段工艺合成了高聚合度的聚磷酸铵（APP）阻燃材料,其结构经XRD,粒度及平均聚合度表征。优化反应条件为：磷酸氢二铵1mol,n（磷酸氢二铵）：n（五氧化二磷）：n（脲）：1．0：1．0：0．3．干燥氨气氛下于290℃反应30min,再经250℃-280℃后处理100min-110min。APP的平均聚合度大于150,粒度小于50μm。     

Experimental and Computational Study of the Thermal Decomposition of 3‐Methyl‐3‐buten‐1‐ol in m‐Xylene Solution

An experimental study of the thermal decomposition of a β‐hydroxy alkene, 3‐methyl‐3‐buten‐1‐ol, in m‐xylene solution, has been carried out at five different temperatures in the range of 513.15–563.15 K. The temperature dependence of the rate constants for the decomposition of this compound in the corresponding Arrhenius equation is given by ln k (s^?1) = (25.65 ± 1.52) ? (17,944 ± 814) (kJ·mol^?1)·T^?1. A computational study has been carried out at the M05–2X/6–31+G(d,p) level of theory to calculate the rate constants and the activation parameters by the classical transition state theory. There is a good agreement between the experimental and calculated rate constants and activation Gibbs energies. The bonding characteristics of reactant, transition state, and products have been investigated by the natural bond orbital analysis, which provides the natural atomic charges and the Wiberg bond indices. Based on the results obtained, the mechanism proposed is a one‐step process proceeding through a six‐membered cyclic transition state, being a concerted and slightly asynchronous process. The results have been compared with those obtained previously by us (Struct Chem 2013, 24, 1811–1816) for the thermal decomposition of 3‐buten‐1‐ol, in m‐xylene solution. We can conclude that in the compound studied in this work, 3‐methyl‐3‐buten‐1‐ol, the effect of substitution at position 3 by a weakly activating CH₃ group is the stabilization of the transition state formed in the reaction and therefore a small increase in the rate of thermal decomposition.     

Structural and Kinetic Aspects of Blood Plasma Protein Adsorption on the Surface of Hydrophobic Polymers

Abstract

Due to the wide use of polymers in medicine, researchers are required to solve a very important problem–to understand the interaction between materials of nonphysiological origin and the surrounding biological liquids, and tissues, particularly blood.     

A simple method for extracting both active oily and water soluble extract (WSE) from Nigella sativa (L.) seeds using a single solvent system

The current study provides a way of extraction for both active NSO and WSE from Nigella sativa seeds using 98% methanol. About 1?kg of ground seeds was macerated by 1:2.5 w/v (g/mL) for 72?hours. After rotary evaporation and 7 days of continuous drying and chilling at 50 and 4?°C, NSO and WSE were obtained at the same instant. Solubility tests of 24 solvents and 11 thin layer chromatographic analyses while 2, 2-diphenyl-1-picrylhydrazyl free radical scavenging assay of NSO (73.66) , WSE (33.32) and NSO?+?WSE (78.22) against ascorbic acid (IC50?=?4.28?mg/mL) was performed. WSE was found to be highly soluble in water and 5% NaOH exhibiting the same Rf value of 0.95 for EtOH:DMSO (9:1) against the honey. WSE has revealed more than twofold higher anti-oxidant activity than others. Formulation of WSE with Tualang honey may provide better targeted hydrophilic drug delivery systems.