Oxygen hydrogen insertion

The second route for ether formation is initiated by protonation of the carbene followed by capture of the cation with alcohol (8). Finally a concerted insertion into the oxygen-hydrogen bond of the alcohol (8) has been considered, but there is no experimental support for this path. The... 

An alcohol can be viewed as the product of the first step in the oxidation of a hydrocarbon because there is an oxygen atom inserted between a carbon and a hydrogen. The addition of oxygen (or insertion) is one of the definitions of oxidation. If another oxygen atom is inserted on the same carbon and water is eliminated, the result is an aldehyde (if the carbon is at the end of the chain) or a ketone (if the carbon is in the middle of the chain). Inserting one more oxygen on the carbon of an aldehydes results in an acid—this is a carboxylic acid with the affected carbon often referred to as a carboxylic carbon (—COOH). 

Stepwise, but heterolytic, mechanisms have been suggested in the insertion of carbenes into oxygen-hydrogen bonds. The reactivity of water and halide ions towards dihalomethylenes parallels their reactivity in Sn2 displacements (Hine and Dowell, 1954), suggesting that an electrophilic carbene attacks water initially by way of the non-bonded electron pair on oxygen giving an ylid (equation 21). An analogous mechanism could be followed in the insertion of carbenes into the... 

The carbonylation of alcohols can proceed with formation of carboxylic acid by catalytic insertion of CO into the carbon-oxygen bond. An alternative reaction gives rise to oxalate or formate esters, when the CO is inserted into the oxygen-hydrogen bond. The members of the nickel triad carbonylate alcohols to give each of these products, and they will be discussed separately. 

Dcluxarclie e/ at. proposed a mechanism w hich is based on CO insertion into the oxygen-hydrogen bond of a surface hydroxyl group (Equation (41)) [1701 ... 

It clearly appears that a single and isolated metallic ion site cannot take into account all the necessary transformations involved in the reaction since several steps as replenishing of oxygen anion vacancies, H atoms extraction and electrons transfer are concerned. For instance n-butane oxidation reaction to maleic anhydride necessitates 7 lattice oxide ions, 8 hydrogen atoms abstraction from the substrate, 3 oxygen atoms insertion and 14 electrons transfer ... 

The photoinduced generation and reactions of dimethylsilylene, McjSi, continue to attract attention. The insertion of dimethylsilylene, prepared by irradiation of dodecamethylcyclohexasilane, into the oxygen-hydrogen bond of alcohols to yield alkoxydimethylsilanes has been used to probe the effect of solvent on dimethylsilylene react vity. Dimethylsilylene is more selective in diethyl ether or tetrahydrofuran than in hydrocarbon solvents and this has been attributed to the formation of complexes between dimethylsilylene and donor solvents. Kinetic studies of the insertion reactions of dimethylsilylene have been undertaken. Previous investigations have resulted in the isolation of dimethylsilylene in an argon matrix at 10 K. Further irradiation of dimethylsilylene (299) under the same conditions gave 2-silapropene (300), which in turn is converted into the dimer (301) at 50K. ... 

Adam, W. Mello, R. Curci, R. Oxygen atom insertion into silicon-hydrogen bonds with assistance by dioxiranes. A stereospecific and direct rearrangement of silanes to silanols. Angew. Chem. 1990, 102, 916. 

Subsequent carbonyl hydrogenation, CO insertion and reductive elimination steps can produce organic oxygenates. Hydrogenation of M C(0)-X units and CO insertion reactions are expected to be thermodynamically favorable for virtually any system (Table I, entries l,m) and thus achieving these steps subsequent to metalloformyl formation is primarily dependent on having appropriate mechanistic pathways. 

Fig. 1.2. Tilting of the MOg octahedra on hydrogen insertion into the ReOj-type framework. Symbols , metal O, oxygen and , hydrogen atoms.

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