Competing Reaction Pathways in Gas-Phase Oxidation of CH by Protonated HO.

Reactions between protonated hydrogen peroxide and benzene (and benzene-) have been studied in the gas phase using an FT-ICR mass spectrometer. Four competing paths for the bimolecular system were identified, namely, proton transfer, hydride abstraction, dissociative single-electron transfer, and an electrophilic addition of HO to give the Wheland intermediate [CH, OH] followed by a subsequent elimination of water. The three latter pathways correspond to three different ways to oxidize benzene.

Gas phase models of hydride transfer from divalent alkaline earth metals to CO and CHO.

The reactivity of HMg, HMgCl, and HMgCl in hydride transfer reactions with CO and CHO were studied by means of the reverse reactions-decarboxylation of HCOMgCl and deformylation of CHOMgCl ( = 0-2)-by a combination of quantum chemical computations and mass spectrometry experiments. HCOMg, HCOMgCl and HCOMgCl display similar energetics for unimolecular carbon dioxide loss; for CHOMg, CHOMgCl and CHOMgCl, formaldehyde loss is more favourable for the cationic species than for the anionic one, with the neutral species found in-between. Despite very similar overall thermochemistry for each of the charge states of the CO and CHO systems, the intermediate reaction barriers are higher for the CO eliminations due to a more complex and demanding reaction mechanism.

Mechanisms for sonochemical oxidation of nitrogen.

NO, and mixtures of N and O, dissolved in water-both in the presence and absence of added noble gases-have been subjected to ultrasonication with quantification of nitrite and nitrate products. Significant increase in product formation upon adding noble gas for both reactant systems is observed, with the reactivity order Ne < Ar < Kr < Xe. These observations lend support to the idea that extraordinarily high electronic and vibrational temperatures arise under these conditions.

The unimolecular dissociation of magnesium chloride squarate (ClMgCO) and reductive cyclooligomerisation of CO on magnesium.

In this paper, we present an investigation of the unimolecular dissociation of an anionic magnesium chloride squarate complex, ClMgC4O4- using mass spectrometry supported by theoretical reaction models based on quantum chemical calculations. Sequential decarbonylation is the main fragmentation pathway leading to the deltate and ethenedione complexes, ClMgC3O3- and ClMgC2O2-, and MgCl--yet the monomer, ClMgCO-, is not observed. Calculations using the G4 composite method show that the latter is unstable with respect to further dissociation.