نتایج جستجو برای: olefin copolymerization
تعداد نتایج: 5669 فیلتر نتایج به سال:
For a reaction to be generally useful for protein modification, it must be site-selective and efficient under conditions compatible with proteins: aqueous media, low to ambient temperature, and at or near neutral pH. To engineer a reaction that satisfies these conditions is not a simple task. Olefin metathesis is one of most useful reactions for carbon-carbon bond formation, but does it fit the...
Light activation is a most desirable property for catalysis control. Among the many catalytic processes that may be activated by light, olefin metathesis stands out as both academically motivating and practically useful. Starting from early tungsten heterogeneous photoinitiated metathesis, up to modern ruthenium methods based on complex photoisomerisation or indirect photoactivation, this surve...
Copolymerization of ethylene with polar vinyl monomers to yield functionalized and possibly easier recyclable polyolefins is challenging it currently being pursued mainly using expensive Pd-based catalysts. Herein, the copolymerization methyl acrylate (MA) achieved by dibenzocycloheptyl-substituted aryliminopyridyl Ni(II) complexes, affording copolymers selectively in-chain incorporated MA unit...
A highly selective cascade reaction that allows the direct transformation of dienallenes to spirocyclobutenes (spiro[3.4]octenes) as single isomers has been developed. The reaction involves formation of overall four C-C bonds and proceeds via a palladium-catalyzed oxidative transformation with insertion of olefin, olefin, and carbon monoxide. Under slightly different reaction conditions an addi...
The interplay between olefin metathesis and dendrimers and other nano systems is addressed in this mini review mostly based on the authors' own contributions over the last decade. Two subjects are presented and discussed: (i) The catalysis of olefin metathesis by dendritic nano-catalysts via either covalent attachment (ROMP) or, more usefully, dendrimer encapsulation - ring closing metathesis (...
The asymmetric synthesis of [7]helicene was accomplished in good ee (80%) by kinetic resolution by means of asymmetric olefin metathesis. Three key factors contributed to the success of the kinetic resolution: the use of new Ru-based olefin metathesis catalysts bearing C1-symmetric N-heterocyclic carbene ligands, simple olefins as additives to control the nature of the propagating alkylidene an...
Production of sodium alpha olefin sulfonates from a variety of normal alpha olefin blends has been studied at the pilot plant scale. Results for the sulfonation, neutralization, and hydrolysis of commercial grade C14, C1416, C1418, and C1224 normal alpha olefins are presented, and the application of a new surfactant drying technology for producing ultra-concentrated AOS is discussed. Physical p...
Herein we report the formation and interesting reactivity of several azepino[4,5-b]indole heterocycles. Initially, a key intramolecular Heck reaction is used to efficiently create the azepino[4,5-b]indole seven membered ring containing an exocyclic double bond. Treatment of the olefin with ozone results in an unprecedented secondary reaction of the Criegee intermediate, through intramolecular o...
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