Two-stage oxidation

The two-stage oxidation described in the present preparation is new and appears to be more convenient than any of the procedures referred to above. 

Because of limitations on the ready availability of HCN, particularly in Japan, processes involving the oxidation of C4 intermediates have been developed and are now replacing the older route developed by Crawford. One important process is based on the two-stage oxidation of isobutylene or -butyl alcohol to methacrylic acid, which is then separated and esterified Figure 15.5a). 

The first two stages (oxidation of Viv to Vv and complex formation) were proved but the third stage predicting the heterolysis of the O—O bond with the addition of OH+ at the double bond is speculative. Heterolysis of this type is doubtful because of the very high energy of the heterolytic cleavage of RO—OH to RO- and OH+. 

Bhattacharyya et al.100 and Mann and Dosi101 both observed a two-stage oxidation-reduction mechanism although with somewhat different kinetic expressions. Malinski et al.55 studied the catalytic activities of the vanadates of Fe, Co, and Ni. The highest yields of formaldehyde were obtained with atomic ratios V/Me = 1 and the catalyst with Ni was the most selective. I.r. spectra taken before and after methanol oxidation show different stabilities of the (V=0) bond, which is most constant in the V-Ni system. 

The thermodynamically favored reaction paths for one- or two-stage oxidation of propene are ... 

Two Stage Oxidation-Reduction.—The completely oxidized, i.e., holo-quinone, form of a quinone differs from the completely reduced, i.e., hydroquinone, form by two hydrogen atoms, involving the addition or removal, respectively, of two electrons and two protons in one stage, viz.,... 

The products of the oxidation reactions can be used to distinguish between primary, secondary and tertiary alcohols. A primary alcohol undergoes a two-stage oxidation via an aldehyde to a carboxylic acid, whilst a secondary alcohol gives a ketone. Tertiary alcohols do not react under mild conditions. Potassium permanganate can also be used to oxidize alcohols. 1,2-Diols are oxidized specifically by sodium periodate. 

Table VIII. Economic Evaluation of the One-Stage and Two-Stage Oxidation of Ethylene to Acetaldehyde ...

Meth)acrylic acid and esters are large-volume industrial chemical intermediates for the production of co- and homopolymers. Acrylic acid (AA), with a worldwide production of approx. 1.5 X 10 t/a, finds its main use in the manufacture of superabsorbent polymers and various acrylate esters. The most important production process for AA involves the two-stage oxidation of propene (via acrolein) in the presence of a large excess of steam by heterogeneous catalysts. Selectivities to AA for the overall process reach 85-90% based on propene (cf. Chapter 1, Introduction). 

Lee YH, Chung MC, Lin Q, Boelsterli UA. Troglitazone-induced hepatic mitochondrial proteome expression dynamics in heterozygous Sod2(+/-) mice Two-stage oxidative injury. Toxicol Appl Pharmacol. 2008 231(1) 43-51. 

Sodium peroxide, NaaOj, is formed when sodium is burned in an atmosphere of oxygen. It was originally made by exposing molten sodium to air in shallow trays, carried on a conveyor through a furnace heated to approximately 300°C. An improved method which is now in universal use consists of a two stage oxidation ... 

Fig. 5. Theoretical Electrometric Titration Curves of Organic Substances, Showing Two-stage Oxidation Resulting from Presence of Semiquinones.

Fig. 12.4, Adipic acid production by two-stage oxidation orcyclohexane With air (boric acid) and nitric acid. Scientific Design process.

It has been reported earlier that oxidation at higher temperature affects the property of the bitumen in terms of its hardness represented by penetration. Explanation of oxidised bitumen Ccin be considered into two stages oxidation of oils to resins, and conversion of resins to asphaltenes. The first step is a heterogeneous process (Gas-liquid) and the rate depends on the mass transfer area. The second step is a homogeneous process and its rate is expected to be influenced, by temperature only when bitumen is oxidised at 250 C at a fixed air rate, the rate of the first step is relatively lower than of the second step so that oxidation leads to a decrease of resin content, which in turn affects the penetration value. 

Figure 4 Concept of two-stage oxidative stress model i skin.

Nowicki NR, Lowry JD. (1990, Jan 9) Inventors Amoco Corp. Assignee. Continuous two-stage oxidation of aromatic hydrocarbons to aromatic carboxylic acids in an aqueous system. U.S. Patent 4892970. 

Tsai (1993) [223] used the AI to classify the degree of oxidation and found that a fiber with a low AI would give a carbon fiber with better mechanical properties when treated by a two stage oxidation process. An oxidized fiber with AI value greater than 50% will itself have poor properties and will, therefore produce carbon fiber with poor properties. 

FIGURE 41.9 SNMS depth profile of a FeCrAl alloy after two-stage oxidation. First stage 4 h in I6O2 second stage 16 h in I8O2 (courtesy of L. Niewolak, FZ Juelich, Germany). 

Scheme 1.1 shows the two-stage oxidation of Ultranox 626 diphosphite to form the diphosphate compound, XR 2502. The LD/EI/FT/ICR mass spectrum in Figure 1.22b shows the predominant molecular ion signal (m/z 636) for the diphosphate, XR 2502, along with residual signals from incompletely oxidised phosphite precursor at m/z 620 (half-oxidised monophosphate) and m/z 604 (nnoxidised phosphite). 

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