C2H5 radical

The C2H5 radicals produced in the first step react with 02 forming C2H502 radicals that in turn convert NO into N02 and generate C2HsO radicals ... 

In Ag-SAPO-ll/C2H4 zeolite the EPR at 77 K shows the spectra of Ag° atoms and C2H5 radicals. After annealing at 230 K those species disappeared and then an anisotropic EPR sextet was recorded. Based on DFT calculation the structure of complex was proposed in which two C2H4 ligands adopted eclipsed confirmation on either side of the Ag atom. As a result the overwhelming spin density is localised on ethylene orbitals. 

Independent studies, including the addition of ethane to Do + 02 mixtures, are planned to evaluate any small occurrence of Reaction 26e, but in the meantime the results for ethane have been interpreted using Equation h which can be derived from Equation g by assuming all C2H5 radicals are converted to oxidation products. 

These ratios are reasonably consistent with those obtained from second-limit inhibition studies (2), but detailed comparison is premature because (a) the present analysis needs refinement as indicated earlier, and (b) the values from second-limit studies are based on the assumption that all C2H5 radicals give chain termination and also give the combined effect of OH + RH and O + RH. 

It seems likely that the major proportion of C2H40 is formed from C2H4 rather than C2H5 radicals, and this view is confirmed from studies where C2H4 has been used as the additive and from analysis data for propion-aldehyde oxidation at 440°C. where C2H4 and CH3CHO are primary products, but the concentration profile for C2H40 is distinctly autocata-lytic in character (8). The same conclusion has been reached by Knox and Wells (15). 

This approach, along with the use of H(D) atoms and CH3 and C2H5 radicals as paramagnetic probes, was further applied to reveal the nature of other types of diamagnetic defects stabilized on the Si02 surface [18,51,52,73],... 

The historical development of the chemistry of organosilicon compounds is closely related to organometallic chemistry. In Bansen s laboratory about the middle of the nineteenth century, Frankland was investigating the reactions of C2HsI with Zn to withdraw the iodine from the C2H5I and form free C2H5 radicals. The product formed was diethyl zinc. It was soon discovered that an ethyl group could be transferred to other elements from this compound if the reaction were favored by the formation of a salt. 

At 220 °C peracid or peracid/aldehyde branching is still probable, and since for high O2/C2H5CHO ratios the kinetics resemble those obtained below 150 °C, the overall mechanism is almost certainly the same as that at the lower temperatures with additional complications arising from RCO decomposition and the subsequent reactions of C2H5 radicals. Since the amount of CO2 produced after the peracid maximum (Fig. 27) is approximately the same as the amount of peracid lost, it seems reasonable to suppose that, as at the lower temperature, CO2 is produced in the branching process. 

In addition to these steps, the mechanism must include radical-radical termolecular recombination reactions. The key feature of this mechanism is the competition between H and N for C2H5 radicals as indicated in steps (8) and (9). The addition of hydrogen atom reactions to the mechanism brings the NO titration and C2H4 reaction estimates of N atom concentrations into fair agreement. 

The dynamics of the H-I-C2H4 association step deposits the 40 kcal/mol reaction exothermicity and the 30 kcal/mol relative translational energy non-randomly in the energized C2H5 radical, with the C-H bond, that is formed, preferentially excited as compared to the other C-H bonds. The expectation is that this non-random excitation may lead to an initial dissociation rate that is larger than that of RRKM theory. However, C2H5 is... 

In the uninhibited pyrolysis of ethane a certain amount of butane is formed, the rate of its formation being roughly or i of that of the CH4 formation butane is formed from the combination of C2H5 radicals. Even at the lowest NO pressures used in our experiments, no C4H10 could be detected. Evidently the NO markedly cuts down the C2H5 concentration, so that the rate of the bimolecular combination reaction is very strongly reduced. 

It appears to be established that, at low temperatures, the reaction order is close to i and that the experimental results can be interpreted by a simple Rice-Herzfeld mechanism. At higher temperatures, the decomposition of the C2H5 radical becomes significant and the mechanism discussed above describes the kinetic data (at small conversions). There are, however, definite indications that at higher conversions and temperatures several secondary reactions occur resulting in the formation of a number of minor products. The kinetics of the reaction is rather complex under such circumstances. If these reactions can be neglected (small conversions), the mechanism is resonably described by steps (3)-(9). The steady-state treatment leads to... 

Reaction numbers for specific radicals are usually given a further letter. For example, (5Ae) refers to the reaction of C2H5 radicals with O2 to give the conjugate alkene (AB), C2H4 and the HO2 radical. 

Evidence for the formation of C2H5S radicals according to reaction (31) has been obtained by studying the change in the ESR spectrum with increasing temperature. 

This equation is readily tested where products from both Si and S2 can be measured. The total yields of CH3 and C2H5 radicals formed from solutions of methyl bromide + ethyl bromide and methyl chloride + ethyl bromide (69) are shown in the next to the last columns of Tables V and VI. These totals agree well with the values given in the last column, calculated using Equation IX and a8 values derived from the single solute systems. 

The loses its kinetic energy and is stabilized as an iodine atom or iodide ion it can also be recaptured by the C2H5 radical (retention of activity in C2H5I). In addition to the necessity that the recoiling species have sufficient energy to rupture the bond, it is also necessary for a successful enrichment of specific activity by the Szilard-Chalmers process that there is no rapid exchange at thermal energies between the active and inactive iodine atoms in ethyl iodide ... 

---