Olefins oxidative degradation

Polyisobutylene has the chemical properties of a saturated hydrocarbon. The unsaturated end groups undergo reactions typical of a hindered olefin and are used, particularly in the case of low mol wt materials, as a route to modification eg, the introduction of amine groups to produce dispersants for lubricating oils. The in-chain unsaturation in butyl mbber is attacked by atmospheric ozone, and unless protected can lead to cracking of strained vulcanizates. Oxidative degradation, which leads to chain cleavage, is slow, and the polymers are protected by antioxidants (75). 

CL must be very carefully purified to exclude small concentrations of (1) ferric ions which would catalyze die thermal oxidative degradation of polycaprolactam and (2) aldehydes and ketones which would markedly increase oxidizability of CL. The impurities in CL may retard die rate of CL polymerization as well as having a harmful effect on die properties of die polymer fiber. In die vacuum depolymerization of nylon-6, a catalyst must be used because in die absence of a catalyst by-products such as cyclic olefins and nitrides may form, which affects the quality of die CL obtained.1... 

Oxidative damage, role of ascorbic acid in preventing, 25 769 Oxidative degradation, 70 682 of gasoline, 72 399-400 Oxidative dehydrogenation, 23 342-343 Oxidative pyrolysis, 27 466 Oxidative stability, of olefin fibers, 77 229 Oxidative stability test, 72 400 Oxide crystal glass-ceramics, 72 641 Oxide-dispersion-strengthened alloys, 77 103-104... 

On the other hand, the storage stability of biodiesel is adversely affected by the presence of unsaturated alkyl components. The olefinic moieties in biodiesel fuel can undergo oxidative degradation via exposure to air with deleterious results, including formation of solids and gums. The degree of oxidative degradation has been shown to increase with fuel unsaturation. 

Moreover, XPS data also indicate that this Os reduction may be accompanied by oxidative degradation of the polymer. Not only the Os speciation but also the oxidant preference seem different for Herrmann s Os/PVP catalyst. Only H2O2 was an effective oxidant even in this case, extreme oxidant excesses were applied to convert the olefins ... 

The carbon of the olefinic group at which the addition reaction occurs becomes again a tertiary carbon bearing a hydrogen, and the oxidative degradation is again initiated (see Figure 8). 

Barbier-Wieland degradation. Stepwise carboxylic acid degradation of aliphatic acids (particularly in sterol side chains) to the next lower homo log. The ester is converted to a tertiary alcohol that is dehydrated with acetic anhydride, and the olefin oxidized with chromic acid to a lower homologous carboxylic acid. 

We report here the hydrogenation of cycloalkenes using Rh-supported montmorillonite as a catalyst. The catalyst preparation was based on oxidative degradation of intercalated tris-(phenanthroline)-Rh(III) followed by reduction under hydrogen atmosphere. There is no obvious trend observed in the hydrogenation yields of the olefins. The most notable difference in the hydrogenation behaviour is seen in case of cyclopentene/cyclooctene both olefins could be efficiently hydrogenated in their pure form but there was no conversion of cyclooctene in presence of cyclopentene. 

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