The Experts below are selected from a list of 11253 Experts worldwide ranked by ideXlab platform
James V. Crivello - One of the best experts on this subject based on the ideXlab platform.
-
SYNTHESIS OF ALKYL AND ARYL 1-Propenyl ETHER MONOMERS: A NEW APPROACH
Journal of Macromolecular Science Part A, 1999Co-Authors: James V. Crivello, S. Kong, L. HarvilchuckAbstract:A new, convenient synthesis of alkyl and aryl 1-Propenyl ether monomers in good to excellent yields has been developed. Alkyl and aryl allyl ethers can be smoothly isomerized to the desired 1-Propenyl ethers by refluxing in a basic ethanolic solution containing pentacarbonyliron as a catalyst. A simplified two-step, one-pot procedure has also been developed which consists of combining an alcohol with allyl bromide in the presence of base and then adding pentacarbonyliron to isomerize the in-situ generated allyl ether to directly give the 1-Propenyl ether. Good yields of alkyl 1-Propenyl ethers were obtained using this process. Factors affecting the isomerization reaction were investigated and a mechanism was proposed.
-
Novel hybrid monomers bearing cycloaliphatic epoxy and 1-Propenyl ether groups
Macromolecules, 1999Co-Authors: Surésh K. Rajaraman, William A. Mowers, James V. CrivelloAbstract:The synthesis of a novel series of hybrid monomers containing cationically polymerizable cycloaliphatic epoxide and 1-Propenyl ether functional groups in the same molecule has been conducted. Detailed structure−reactivity studies of the diaryliodonium salt-induced cationic photopolymerizations of these monomers indicate that the rate of epoxide ring-opening polymerization is markedly enhanced by the presence of the 1-Propenyl ether group. At the same time, the polymerization of the 1-Propenyl ether groups in such hybrid monomers is retarded. A mechanism involving the free-radical-induced decomposition of the photoinitiator has been proposed which serves to amplify the rate of the photoinitiated cationic epoxide ring-opening polymerization.
-
Synthesis and Photopolymerization of 1-Propenyl Ether Functional Siloxanes
Chemistry of Materials, 1996Co-Authors: James V. Crivello, G. LöhdenAbstract:A variety of mono-, di-, and multifunctional 1-Propenyl ether functional siloxanes were readily prepared in high yields by the transition-metal-catalyzed condensation of α-(1-Propenyl) ω-vinyl ethers with various linear and cyclic hydrogen functional siloxanes. Under these conditions, hydrosilation takes place regioselectively at the vinyl ether site of the α-(1-Propenyl) ω-vinyl ether. Using onium salt photoinitiators, these new monomers and oligomers undergo rapid polymerization under the influence of UV light. To study these very fast photopolymerizations, extensive use of Fourier transform real-time infrared spectroscopy was made. Employing this technique, the effects of monomer and photoinitiator structure on the rates of polymerization were studied.
-
Chemoselective hydrosilations. I. Synthesis and photopolymerization of 1‐Propenyl ether functionalized siloxanes
Journal of Polymer Science Part A: Polymer Chemistry, 1995Co-Authors: James V. Crivello, Bo Yang, Whan-gi KimAbstract:The synthesis of 1-Propenyl ether-functionalized siloxanes (PFS) has been achieved by the controlled, rhodium-catalyzed, chemoselective hydrosilation of 1-allyloxy-4(1-propenoxy)butane with various H-functional siloxanes. It was shown that the hydrosilation proceeds exclusively at the allyl ether group of 1-allyloxy-4(1-propenoxy)butane without participation at the 1-Propenyl ether group. The photoinduced cationic polymerization of these monomers was studied using various analytical techniques and found to take place very rapidly. © 1995 John Wiley & Sons, Inc.
-
Synthesis, characterization, and polymerization of Propenyl ether analogues
Journal of Polymer Science Part A: Polymer Chemistry, 1994Co-Authors: James V. Crivello, A. M. Carter, S. A. BratslavskyAbstract:A series of aromatic monomers bearing cationically polymerizable Propenyl groups were prepared and characterized using the readily available starting materials: isoeugenol and o-allyl phenol. Monomers with both Propenyl and vinyl ether functional groups were also synthesized by the reaction of these starting materials with chloroethyl vinyl ether. The reactivity of the resulting monomers in photoinitiated cationic polymerization was studied using differential scanning photocalorimetry and photogel point measurements. Their thermal properties were determined using thermogravimetric analysis. © 1994 John Wiley & Sons, Inc.
Hossam Haick - One of the best experts on this subject based on the ideXlab platform.
-
Controlling the Sensing Properties of Silicon Nanowires via the Bonds Nearest to the Silicon Nanowire Surface.
ACS applied materials & interfaces, 2015Co-Authors: Jeffrey M. Halpern, Bin Wang, Hossam HaickAbstract:Controlling the sensing properties of a silicon nanowire field effect transistor is dependent on the surface chemistry of the silicon nanowire. A standard silicon nanowire has a passive oxide layer (native oxide), which has trap states that cause sensing inaccuracies and desensitize the surface to nonpolar molecules. In this paper, we successfully modified the silicon nanowire surface with different nonoxide C3 alkyl groups, specifically, propyl (Si–CH2–CH2–CH3), Propenyl (Si–CH═CH–CH3), and propynyl (Si–C≡C–CH3) modifications. The effect of the near surface bond on the sensor sensitivity and stability was explored by comparing three C3 surface modifications. A reduction of trap-states led to greater sensor stability and accuracy. The Propenyl-modified sensor was consistently the most stable and sensitive sensor, among the applied sensors. The Propenyl- and propynyl-modified sensors consistently performed with the best accuracy in identifying specific analytes with similar polarity or similar molecular we...
Munetaka Akita - One of the best experts on this subject based on the ideXlab platform.
-
Trifluoromethylation of aromatic alkenes by visible-light-driven photoredox catalysis: Direct conversion of alkenes to 3-trifluoromethyl-1-Propenyl and 1,3-bis(trifluoromethyl)-1-Propenyl derivatives
Journal of Fluorine Chemistry, 2015Co-Authors: Masashi Asano, Ren Tomita, Takashi Koike, Munetaka AkitaAbstract:Abstract Photoredox-catalyzed trifluoromethylation of alkenes using Umemoto's reagent as a CF3 source under visible light irradiation has been developed. A Ru photocatalyst, [Ru(bpy)3](PF6)2 (bpy = 2,2′-bipyridine), is useful for the present trifluoromethylation and preferable formation of 3-trifluoromethyl-1-Propenyl derivatives is observed. Use of an excess amount of Umemoto's reagent readily induces double trifluoromethylation of electron-rich alkenes, resulting in 1,3-bis(trifluoromethyl)-1-Propenyl skeleton.
Norbert De Kimpe - One of the best experts on this subject based on the ideXlab platform.
-
Synthesis of pyranonaphthoquinone antibiotics involving the ring closing metathesis of a vinyl ether
Tetrahedron Letters, 2004Co-Authors: Norbert De KimpeAbstract:The synthesis of two antibiotic pyranonaphthoquinones was performed by a straightforward synthetic route utilizing ring closing metathesis. Vinylation of 3-(1-Propenyl)-2-hydroxymethyl-1,4-dimethoxynaphthalene under iridium catalysis and subsequent ring closing metathesis of 3-(1-Propenyl)-2-vinyloxymethyl-1,4-dimethoxynaphthalene with Grubbs' catalyst paved the way to the natural antibiotics pentalongin and psychorubrin.
Jeffrey M. Halpern - One of the best experts on this subject based on the ideXlab platform.
-
Controlling the Sensing Properties of Silicon Nanowires via the Bonds Nearest to the Silicon Nanowire Surface.
ACS applied materials & interfaces, 2015Co-Authors: Jeffrey M. Halpern, Bin Wang, Hossam HaickAbstract:Controlling the sensing properties of a silicon nanowire field effect transistor is dependent on the surface chemistry of the silicon nanowire. A standard silicon nanowire has a passive oxide layer (native oxide), which has trap states that cause sensing inaccuracies and desensitize the surface to nonpolar molecules. In this paper, we successfully modified the silicon nanowire surface with different nonoxide C3 alkyl groups, specifically, propyl (Si–CH2–CH2–CH3), Propenyl (Si–CH═CH–CH3), and propynyl (Si–C≡C–CH3) modifications. The effect of the near surface bond on the sensor sensitivity and stability was explored by comparing three C3 surface modifications. A reduction of trap-states led to greater sensor stability and accuracy. The Propenyl-modified sensor was consistently the most stable and sensitive sensor, among the applied sensors. The Propenyl- and propynyl-modified sensors consistently performed with the best accuracy in identifying specific analytes with similar polarity or similar molecular we...
