Relative rates oxidation

A semi-quantitative indication of the effects of different elements on the resistance to oxidation of nickel is given in Table 7.15 which lists values for the relative oxidation rate with respect to that of nickel for different concentrations of solute element. These values are approximately valid over quite wide ranges of time and temperature. ... 

The main mechanistic difficulty involves Ce(IV) sulphate and V(V), which attack ketones at rates less than those of enolisation. The kinetics and relative oxidation rates are of little assistance in discriminating between attack on keto and enol forms. However, the solvent isotope effects in these oxidations are in strict accord with the measured acidity-dependences if attack had occurred on the enol then the change of solvent should have enhanced the expected koiolf HiO l y a factor of 2.5, because is favoured to such an extent in D2O as compared with H2O. No such enhancement is found and attack is, therefore, on the keto... 

The metabolism studies with cyanide present showed no dehydrogenation whatsoever of the substrate. It is thus considered likely that the resazurin and the resorufin interact with some metal bearing system, possibly the cytochromes participating in the hydrogen transfer. Although the resazurin (or resorufin) may interact in a system several steps removed from the dehydrogenation of the particular substrates, the relative rates of reduction of the indicator are still comparable with the relative oxidation rates of the substrates. 

Figure 3. Relative oxidation rates of various methoxyl-substituted benzyl alcohols, measured by oxygen consumptionAnin. (veratryl alcohol = 100). No oxidation of the lower four alcohols was detected.

Figure 4. Relative oxidation rates of various aromatic alcohols. Para-hydroxyl substitution eliminates substrate oxidation.

Relative oxidation rates of some aromatic hydrocarbons... 

The distinguishing feature of tyrosinase is that it catalyzes the oxidation of monohydric phenols, like tyrosine, to the dihydric form and dihydric phenols, like DOPA and catechol, to the corresponding quinones. The striking biological effects of this enzyme arise from quinones which polymerize to produce the darkening of various plants on injury and melanin in mammals. The relative oxidation rates of several dihydric phenols by tyrosinase are given in Table III. 

In order to explain the reason that marine oils are much more labile than common vegetable oUs, basic lipid chemistry, such as oxidation rate, induction period, and oxygen uptake were determined and reported by several researchers (70-72). The relative oxidation rates of fatty esters at 36.5°C were found to be highly... 

Caicuiated Inherent Oxidative Stability = Sum of the decimal fraction of each unsaturated fatty acid times its relative oxidation rate. 

Fatty Acid Approximate Relative Oxidation Rate (PV formation)... 

The relative oxidation rates of pure fatty acid esters based on peroxide formation are shown in Table 1 (6). This table is based on a common factor of one that has been arbitrarily assigned for the oxidation rate of oleic acid. 

Figure 2. Relative oxidation rates of iso-octane, iso-octane/20% xylene, Phillips Naptha and California reformulated gasoline.

Fig. 7. 3.1 The effect of penetration. Relative oxidation rates vs temperature for two graphite cylinders of linear dimensions in the ratio of two. pc. Duval, J. Chim. Phys., 58, 5 (1961)]...

Figure 5.2. Dependence of the relative rates of various processes on water activity at constant temperature. Curve 1 relative destruction rate of chlorophyll in spinach at 37°C. Curve 2 relative decay rate of ascorbic acid. Curve 3 relative oxidation rate of potato chips stored at 37°C. Curve 4 relative rate of inactivation of phosphatase in skim milk. Curve 5 relative rate of inactivation of Clostridium botulinum. Curve 6 drying rate of a slab of glucose at 30°C slab temperature. (From Thijssen, 1979.)...

The successful use of these alternate oxidants implies that they rapidly oxidize RPt(II) while not oxidizing inorganic Pt(II). (H2O2 does not need to satisfy the second of these criteria it is both an oxidant and a reductant, so a sufficient steady-state concentration of inorganic Pt(II) can be maintained, albeit at the cost of highly inefficient oxidant consumption [19].) Indeed, Cu Cl has been shown to be oxidized by [Pt Clg] [25], so the reverse reaction would not take place. The (relative) oxidation rates have been measured for several oxidants using the methods described above. Rather unexpectedly, Cu Cl2 was found to oxidize [(CH3)-Pt Cl3] faster than [Pt Cle], by around an order of magnitude at 95°C Fe tl3 is somewhat less reactive [16]. 

Fig. 12 Relative oxidation rates by OH radicals of condensed-phase cholestane vs gas-phase m-xylene in different organic-aerosol matrices, all of which include a high fraction of motor oil. Cholestane oxidation is independent of OA concentration or the presence of a substantial SOA coating consisting of up to half of the total particle mass. However, high relative humidity slows cholestane oxidation by an order of magnitude. This suggests that a thin film of water on oil can significantly retard cholestane oxidation, perhaps by excluding the cholestane from the particle surface the SOA, on the other hand, does not coat the particle surface but rather mixes with the oil and thus does not impede cholestane oxidation...

TABLE 6 Induction period and relative oxidation rate after induction period in thermo-oxidative degradation of 0.1 mm PP film at 180°C [49]... 

The exponential increase of relative oxidation rate during weathering ageing emphasizes the contribution of stabilization factors like higher crosslinking or the presence of a proper antioxidant. 

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