We herein report the Et3N catalyzed sp(3) C-H bond functionalization of methyl arenes with active methylene compounds under solvent-free condition using TBHP as an oxidant. These reactions are exclusively enabled by T...
详细信息
We herein report the Et3N catalyzed sp(3) C-H bond functionalization of methyl arenes with active methylene compounds under solvent-free condition using TBHP as an oxidant. These reactions are exclusively enabled by TBHP. The methyl arenes used in this reaction are highly versatile and rapidly undergo oxidation and further condensation with malononitrile /ethylcyanoacetate. This is a metal-free, practical, inexpensive, non-toxic and environmentally benign method.
One of the most useful methods for synthesizing the graft and well-defined copolymers is the atom transfer radical polymerization (ATRP) method. The polymerization was initiated by polystyrene (PS) carrying chloroacet...
详细信息
One of the most useful methods for synthesizing the graft and well-defined copolymers is the atom transfer radical polymerization (ATRP) method. The polymerization was initiated by polystyrene (PS) carrying chloroacetyl groups as macroinitiator, in the presence of copper chloride (CuCl) and bipyridine (bpy). The macroinitiator (chloroacetylated PS) was prepared by successive chloroacetylation of PS under mild conditions and these reaction conditions overcome the problem of gelation and crosslinking in polymers. Successful graft copolymerizations were performed with methyl methacrylate (MMA) in toluene at 80 degrees C and with acrylonitrile (AN) in tetrahydrofuran/ethyl-enecarbonate (62.5/37.5 v/v %) mixed solvent at 55 degrees C. The characterization of the copolymers was investigated by H-1-NMR and FT-IR spectroscopices. Gel permeation chromatography measurement indicated an increase of the molecular weight of the graft copolymers, as compared to that of the macroinitiator. This measurement also indicated the monomodal molecular weight distribution. (c) 2006 Wiley Periodicals, Inc.
Poly(vinyl benzyl amine) (PVBAm) has been synthesized by modifying poly(vinyl benzyl chloride) (PVBC) via an unique synthetic route. According to the literature, most polyamines are synthesized from PVBC through the G...
详细信息
Poly(vinyl benzyl amine) (PVBAm) has been synthesized by modifying poly(vinyl benzyl chloride) (PVBC) via an unique synthetic route. According to the literature, most polyamines are synthesized from PVBC through the Gabriel reaction. In this investigation, we adopt Staudinger synthesis to avoid drastic decomposition which occurs in the Gabriel reaction during synthesis. Three types of polyamine polymers - homopolymer, block copolymer and random copolymer, were synthesized without incurring any crosslinking reaction. The amine-containing polymers can further undergo ring-opening addition reaction with N-phenyl-3,3-dimethyl-azetidine-2,4-dione. Notably, the intermediates, phosphine imine and azide functionalities can be easily converted into various functionalities such as carbodiimide, imine, imine, triazo, aziridine, etc. by adding suitable reagents. (c) 2008 Elsevier Ltd. All rights reserved.
The modal age at death is used to study the shifting mortality scenario experienced by low mortality countries. The relations of the life table functions at the modal age are analyzed using mortality models. In the mo...
详细信息
The modal age at death is used to study the shifting mortality scenario experienced by low mortality countries. The relations of the life table functions at the modal age are analyzed using mortality models. In the models the modal age increases over time, but there is an asymptotic approximation towards a constant number of deaths and standard deviation from the mode. The findings are compared to changes observed in populations with historical mortality data. As shown here the shifting mortality scenario is a process that might be expected if the current mortality changes maintain their pace. By focusing on the modal age at death, a new perspective on the analysis of human longevity is revealed.
暂无评论