Reactions with O atoms

This reaction is similar to the step observed in O atom reactions with ethane. 

Relative concentrations of oxygen atoms were determined from the limiting amount of a primary or a secondary product (or the sum of these) in O atom reactions with the substance studied. The reactant was admitted in sufficient concentrations at various sites of the reaction vessel, and the limiting amount of reaction products was determined. A curve plotted as log (O)0/(O)r vs. X was used for determining the rate constant for the disappearance of atoms. 

The only FPTRMS studies of atom-radical reactions reported are of O atom reactions with methyl and substituted methyl radicals. The reaction... 

This is probably because 0 atoms produced in primary process (45) react much more rapidly with C2H6 than with N20. Several products are formed including ethylene, butane, carbon monoxide, hydrogen, methane, and probably ethanol and acetaldehyde. More ethylene is formed than one would expect from the amount of butane. It was found that 0 atoms react rapidly with ethylene, which is one of the photolytic products. The reaction-rate constant of O atoms with ethylene is estimated to be about 330 times as rapid as that with ethane.82 Complete elucidation of the mechanism of O-atom reaction with ethane is complicated because of the rapid reaction of O atoms with one or more of the products. 

Analysis of all the data on O-atom reactions with squalane and consideration of the various possible reactions of ground state 0( P) and electronically-excited 0( D) lead to a qualitative summary (Fig. 16) of the initial reactions between atomic oxygen and a saturated hydrocarbon surface. The first step leading to the production of volatile reaction products is direct H-atom abstraction by 0( P). The initial OH product may... 

Atmospheric chemistry demands have given a nuuked stimulus to studies of reactions of 0 atoms and OH- radicals with atmospheric substrates at about room temperature and below. Reactions of O atoms with alkenes and aromatics are important in photochemical smog formation and control. Rate constants, and in many cases Arrhenius parameters, are available for a variety of -O atom reactions with alkenes, alkynes, aromatics, unsaturated aldehydes, alkanes, - and carbonyl compounds. In general, the rate constants refer to the ovoall process ... 

Zhao et al. [74] developed a kinetic model to analyze the removal of nitrogen oxides in a pulsed corona discharge in NO/N2 mixtures. They considered reactions of NO and N02 with N and O atoms and with excited N2(A3S) molecules. 

In the presence of oxygen, NO is mainly oxidized to NOz, by reactions with O atoms and with ozone [33,46,76-78], The rate constant of molecular dissociation of 02 by electron collisions is almost two orders of magnitude higher than the dissociation of N2 in... 

Selective denitration of methyl 4,6-O-benzylidene- and 4,6-O-alkyl-idene-D-hexopyranoside 2,3-dinitrates to yield 3-nitrates has also been achieved by using sodium nitrite in ethanol as the reagent.233,238, 241.242 interestingly, when the nitrate group is on a primary carbon atom, reaction with this reagent takes place to give the primary alcohol,232,241,243 but the conversion may, on occasion, proceed only with... 

Besides the oxygen atom reactions discussed earlier, we studied those involving I.2-C2H4CI2,66 NH3,66 and acetylene, cyclohexane, and benzene. At first attempts were made to find an O atom reaction that would be similar and at the same time essential for all substances. This is the ease, for example, for hydrogen atoms and hydroxyl. Hydrogen reacts with saturated hydrocarbons by abstraction of the H atom, and with unsaturated hydrocarbons by addition as well. Hydroxyl is believed to react with hydrocarbons by abstraction of the H atom and formation of water. 

Triply bridging orf/io-phenylene complexes sometimes arise in curious ways. In the reaction of Os3(CO)10(MeCN)2 with salicylaldehyde benzy-limine one would naively expect that coordination would be through N and O atoms as with other metal systems. The first formed compound (40, Scheme 6) results from ortho metallation while, of the three isomeric decarbonylation products (41 to 43), compound 43 contains only Os—C bonds to the ligand and is a ring-substituted version of Os3H2(C6H4)(CO)9 (Scheme 6) (237). 

The Patemo-Biichi reaction is a photocycloaddition reaction of a n,ji carbonyl compound to an alkene in the ground state from either the Si or the rl i state. The reaction can occur through the initial C O bond formation or through a previous formation of the C—C bond. A frontier orbitals approach can be used to explain the formation of oxetanes. We can observe the HSOMO-LUMO interaction in which the half-occupied ji carbonyl orbital interacts with the unoccupied ji molecular orbital of an electron-deficient alkene, and a C,0-biradical is formed. The LSOMO-HOMO interaction in which the half-occupied n orbital of the carbonyl O atom interacts with the ji orbital of an electron-rich alkene, and a C,C-biradical is formed [13, 14]. 

A study of the analogous reaction of O ( D ) with alcohols (Goldstein and Wiesenfeld, 1983), while of no direct atmospheric importance, reveals interesting details concerning the reactive characteristics of electronically excited oxygen atoms and provides information about the unimolecular dissociation dynamics of chemically activated molecules. In the generic case of O ( D2) reaction with methanol, a variety of reactive pathways are available ... 

However, Hoyermann et estimated an upper limit for At2o of 10 l.mole sec. Similarly, Halstead and Thrush found SO to be quite unreactive in such systems except toward O atoms, and claim an upper limit for the rate coefficient for the reaction of SO with itself is 4 x 10 l.mole" sec They argued that Sullivan and Warneck s results could be explained by the removal of SO by reaction (8), the third-order combination with O atoms, together with reaction of SO with OCS... 

The calculated AEs for the formation of oxycarbides indicate that two reaction paths are possible for the C<->0 exchange in 0/ TiC((X)l) or 0/ZrC(001) [23, 24] 0/MC(001) C/MCj p/001), and 0/MC(001) MC,.p/001)+CO(gas). The first one essentially involves one oxygen atom per each carbon atom and does not change the C content of the system. The C atoms replaced by O remain on the surface bonded to CMM sites, see Fig. 6.7 [23, 24]. In the case of the second one, the carbon content of the system decreases. It involves two O atoms per each C atom removed. One O atom takes the place of a C atom in the carbide lattice, and the second O atom reacts with the replaced C to form CO which evolves into gas phase. For OA C(OOl), DF calculations predict that a simple C O exchange is endothermic, and only the second pathway for the C O exchange is allowed thermodynamically [24],... 

E4.43 Equation (b) is better in explaining the observ ations described in the exercise. Most notably it contains the Lewis acid-base adduct [FeCblOPC 1,3)4] in which OPCI3 is a Lewis base and coordinates via its O atom, consistent with vibrational data. It also has the Fe Clb/fFeCy (i.e., red/yellow) equilibrium. The titration would have to start in either case from a concentrated (red) solution, and the equivalence point at 1 1 mole ratio FeClj/Et4NCI can be explained based on the reaction ... 

Without stratospheric ozone (O3), harmful solar radiation would cause gene alterations. Ozone forms when O2 breaks and each O atom reacts with another O2 molecule. It is destroyed by reaction with Cl atoms that are formed when the C—Cl bond in synthetic chemicals breaks. Find the wavelengths of light that can break the C—Cl bond and the bond in O2. 

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