Copper(I)-phenolate complexes as models of the reduced active site of galactose oxidase: synthesis, characterization, and O2 reactivity
B.A. JazdzewskiAnne ReynoldsPatrick L. HollandVictor G. YoungSusan KaderliAndreas D. ZuberbühlerWilliam B. Tolman
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Galactose oxidase
Reactivity
Resonance Raman spectroscopy
The phenoxyl radical plays important roles in biological systems as cofactors in some metalloenzymes, such as galactose oxidase (GO) catalyzing oxidation of primary alcohols to give the corresponding aldehydes. Many metal(II)-phenoxyl radical complexes have hitherto been studied for understanding the detailed properties and reactivities of GO, and thus the nature of GO has gradually become clearer. However, the effects of the subtle geometric and electronic structural changes at the active site of GO, especially the structural change in the catalytic cycle and the effect of the second coordination sphere, have not been fully discussed yet. In this Review, we focus on further details of the model studies of GO and discuss the importance of the structural change at the active site of GO.
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The product distributions of liquid isomerization of 2,10 epoxypinane in the presence of acid catalyst was studied.The influence of reaction temperature,reaction time and the amount of solvent on the isomerization were investigated.It is discovered that the isomerization of 2,10 epoxypinane produced mainly perilly alcohol and myrentol.Perilly alcohol can be obtained from isomerization of 2,10 epoxypinane catalyzed by NH 4NO 3 in CH 3NO 2 with 98 9% conversion and 88 1% selection.
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Abstract A commercial mixture of methylcyclopentadiene dimers mainly consisting of four dimeric compounds with partial structures of 1‐methyl‐ and 2‐methylnorbornene, undergoes slow oxidation and isomerization when it is dissolved in CH 2 Cl 2 , CHCl 3 or CCl 4 . Both reactions are simultaneous but independent of each other. Isomerization only concerns those isomers that contain in their structure a 2‐methylnorbornene ring. The nature of the isomerization and the influence of different acid media is studied.
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Isomerization of saturated hydrocarbons includes skeletal rearrangements and cis-trans isomerization of substituted cycloalkanes. Different catalysts bring about different types of isomerization of hydrocarbons. Acids are the best known and most important catalysts inducing isomerization through a carbocationic process. Bronsted and Lewis acids, acidic solids, and superacids are used in different applications. Significant efforts have been made about the fabrication, characterization, and the use of bifunctional catalysts bearing both acidic and metallic sites in isomerization. Metals are able to induce hydrogenation/dehydrogenation, whereas acid sites are involved in skeletal isomerization. Besides skeletal rearrangements, alkenes may undergo double-bond migration and cis-trans isomerization. Double-bond migration, cis-trans isomerization, and skeletal isomerization are the characteristic isomerization transformations of alkenes in the presence of acidic catalysts. Double-bond migration and cis-trans isomerization are facile transformations that can be induced under mild conditions (relatively mild acids and low temperature).
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Contrary to the hitherto accepted concept that every olefins undergo mutual isomerization between their cis-and trans-isomers, olefins substituted by anthracenyl and other aromatic polycyclic groups undergo only one-way isomerization from their cis-to trans-isomers, and the reverse isomerization from their trans-tocis-isomers never occurs. The mechanism for the one-way isomerization and the features to distinguish one-way or two-way isomerization is discussed to get whole view of the isomerization of olefins.
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