Oxygen eliminations

The pH of the solution is of overwhelming importance in determining the course of these hydrolyses. In basic solution, oxygen elimination is dominant. This is because the unprotonated nitrogen substituent is a very poor leaving group and is also more effective at facilitating the alkoxide elimination by electron donation ... 

Figure 14 Mechanism of oxygen elimination from the structure of BajYC Oy 0. (a) As an effect of temperature increase, atom A may jump into position A (b) As a consequence of this shift, atom B may jump into position B, C into C etc., thus causing a correlated motion of the oxygen atoms terminating with the expulsion of half oxygen atom from the structure (c) Atom C now may jump into positions C or C" generating a second cascade...

Since osmium dioxide trifluoride, OsO zF has not been detected in the products of oxyfluorination of osmium (whereas OsO,F, has) it is unlikely that OsO,F, is unstable with respect to that compound and fluorine. It is more likely that the molecule would degrade by oxygen elimination. It is therefore possible that any... 

The overall rate resulting fi om the occurrence of more than a single process at the phase boundary may control the values of A and so that they are not necessarily directly proportional to the active area of the solid, or equal to the enthalpy of formation of the reactant, respectively. Moreover, when oxygen elimination is accompanied by defect generation, resulting in a change in composition of a non-stoichiometric phase, the enthalpy of reaction cannot in general be expected to be... 

A European patent by Kuno and Matsumoto [43] describes the use of olive plant extract as an effective and stable whitening and antiaging agent. This extract is believed to have strong active oxygen elimination function such that it can eliminate superoxide and hydroxyl radicals and also effectively inhibit melanin production. 

Table 3 Weight loss and corresponding oxygen eliminated...

Much research has been focused on reducing oxide and hydroxide formation in plasmas. Oxide formation depends on such experimental variables as injector flowrate, radio-frequency power, sampler skimmer spacing, sample orifice size, plasma gas contposition, oxygen elimination, and solvent removal efficiencies. All of these variables can be adjusted to address specific oxide and hydroxide overlap problems. 

In eliminations of this type, H is always removed from the carbon p to selenium that is remote from the lactone oxygen. Elimination is syn. 

Although B-0 bonds are much stronger than B-C bonds and thermodynamics favors boron-oxygen elimination from B-C-C-0 linkages to form B-0 + C=C, such elimination from (P-alkoxyalkyl)boronic esters is not normally observed unless the compounds are heated above 50-60 °C. This kinetic stability has allowed the synthesis of a wide variety of alkoxy substituted boronic esters. Synthetic targets are usually hydroxy compounds, for which benzyloxy, (p-methoxybenzyl)oxy, and trityloxy groups are useful precursors. 

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