Hydrogen bonding peroxide

Key Words Lewis acid adducts, Radical oxidations, Epoxidation, Hydrogen peroxide, Bond dissociation energy, Catalyst durability, Methyltrioxorhenium, Cross-bridged cyclam, Mn(IV), Late transition metal. Propylene oxide. Titanium silicalite (TS-1) catalyst, Ethylanthrahydroquinone/H2 process, Polyoxometallates, Mn(IV) catalyst. Hydrogen abstraction. Rebound mechanism, Isotopic label, t-BuOOH, Peroxide adduct. 2008 Elsevier B.v. 

Rotation about the O—O bond is relatively easy. Hydrogen bonding causes even more association of liquid hydrogen peroxide than occurs in water. 

An sp sp- single bond where each of the central atoms is in Group VIA (for example, hydrogen peroxide) has a two fold barrier with optirn iitn torsional an glc of 90 degrees, as described by V2=-2,0 kcal/tnol. 

Structures A B and C represent different conformations of hydrogen peroxide Conformations are different spatial arrangements of a molecule that are generated by rotation about single bonds Although we can t tell from simply looking at these struc tures we now know from experimental studies that C is the most stable conformation... 

Step 2 Anion of hydrogen peroxide acts as a nucleophile attacking boron and forming an oxygen-boron bond... 

Oxidation. The oxidation reactions of organoboranes have been reviewed (5,7,215). Hydroboration—oxidation is an anti-Markovnikov cis-hydration of carbon—carbon multiple bonds. The standard oxidation procedure employs 30% hydrogen peroxide and 3 M sodium hydroxide. The reaction proceeds with retention of configuration (216). 

Free-Radical Formation. Hydrogen peroxide can form free radicals by homolytic cleavage of either an O—H or the O—O bond. 

Oxidation. Ketones are oxidized with powerful oxidizing agents such as chromic or nitric acid. During oxidation, carbon—carbon bond cleavage occurs to produce carboxyHc acids. Ketone oxidation with hydrogen peroxide, or prolonged exposure to air and heat, can produce peroxides. Concentrated solutions of ketone peroxides (>30%) may explode, but dilute solutions are useful in curing unsaturated polyester resin mixtures (see... 

Chemical Properties. Higher a-olefins are exceedingly reactive because their double bond provides the reactive site for catalytic activation as well as numerous radical and ionic reactions. These olefins also participate in additional reactions, such as oxidations, hydrogenation, double-bond isomerization, complex formation with transition-metal derivatives, polymerization, and copolymerization with other olefins in the presence of Ziegler-Natta, metallocene, and cationic catalysts. All olefins readily form peroxides by exposure to air. 

Thermal decomposition of dihydroperoxides results in initial homolysis of an oxygen—oxygen bond foUowed by carbon—oxygen and carbon—carbon bond cleavages to yield mixtures of carbonyl compounds (ketones, aldehydes), esters, carboxyHc acids, hydrocarbons, and hydrogen peroxide. 

Tetracyanoethylene oxide [3189-43-3] (8), oxiranetetracarbonitnle, is the most notable member of the class of oxacyanocarbons (57). It is made by treating TCNE with hydrogen peroxide in acetonitrile. In reactions unprecedented for olefin oxides, it adds to olefins to form 2,2,5,5-tetracyanotetrahydrofuran [3041-31-4] in the case of ethylene, acetylenes, and aromatic hydrocarbons via cleavage of the ring C—C bond. The benzene adduct (9) is 3t ,7t -dihydro-l,l,3,3-phthalantetracarbonitrile [3041-36-9], C22HgN O. 

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