Oxidation products formed

Potassium permanganate does not oxidize the sulfur atom in dibenzo[ft,/]thiepin (1), rather attacking the C —C double bond, which is very similar in reactivity to that in (Z)-stilbene, to provide various oxidation products, formed from ring opening or ring contraction, depending upon the acetone or water reaction medium.20... 

Fig. 8.8 The chemical structures of dinoflagellate luciferin (5), the product of luminescence reaction catalyzed by luciferase (6), air-oxidation product formed at — 20°C (7), and the blue oxidation product (8). Note structural resemblance between these compounds and chlorophylls.

Does methanol (or formaldehyde) oxidation along the direct pathway lead directly to CO2 or are incomplete oxidation products formed first, which are then oxidized further to finally result in CO2 formation (dashed arrows in Fig. 13.8b) ... 

The sulphite aftertreatment is particularly important with permonosulphuric acid treatment. Evidence for the underlying mechanism is available from analysis of sulphur oxidation products formed in the various processes (Table 10.34). It is evident from these results that the concentration of RSS()5 anionic groups necessary to change the hydration of the fibre surface is achieved by the reaction of bisulphite with cystine monoxide residues to give the required cysteine-S-sulphonate groups [311]. 

Table 10.34 Relative amounts of sulphur oxidation products formed during shrink-resist processing of wool [11,311]...

The relatively small amounts of oxidation products formed in tap water are thought to be formed by direct air oxidation. Metabolism by microorganisms may also contribute to the conversion in the water which previously contained fish. 

Subrahmanyam VV, O Brien PJ. 1985. Phenol oxidation products, formed by a peroxidase reaction, that bind to DNA. Xenobiotica 15 873-885. 

Chang, Y.H., Abdalla, D.S., and Sevanian, A., 1997, Characterization of cholesterol oxidation products formed by oxidative modification of low density lipoprotein. Free Radio. Biol. Med. 23 202-214. 

Leadbetter, E.R. and Foster. J.W. Oxidation products formed from gaseous alkanes by the bacterium Pseudomonas methanica. Arch. Biochem. Biophys., 82 491-492, 1959. 

A square-planar Cu -hydroperoxo species 36 was reported to act as a catalyst for the selective oxidation of dimethylsulfide to dimethylsulfoxide (Eq. 20), with no trace of higher oxidation products formed and TON s of up to 300. Also thioanisole could be converted on a catalytic basis [237]. 

Table VI. Rates of Methyl Ethyl Ketone Oxidation Products" Formed by Bimolecular (W2) and Unimolecular (Wi) Routes in Reaction Involving R02 in Benzene Solution (145°C., 50 atm.)...

Tucker (5), however, in 1936 demonstrated that oxidation products, formed in the oil after removal of unsaturates, caused serious toxic effects on apricot leaves. 

Crafts and Reiber (2) suggested that oxidation, accelerated by light, may account for the increased toxicity of stored isoparaflhiic oils. Although the oxidation products formed are not known, they appear to be primarily organic acids. 

A potent disclosure by Pechukas1821 describes the condensation of methyl chJorccarbonate in pyridine at 5 with ethylene oxide and propylene oxide, epichlorohydrio. and styrene oxide. Products formed... 

HRP-based 4CN DAB/NiCV TMB" Oxidized products form purple precipitate Forms dark brown precipitate Forms dark purple stain Not very sensitive (Tween 20 inhibits reaction) fades rapidly on exposure to light More sensitive than 4CN but potentially carcinogenic resulting membrane is easily scanned More stable and less toxic than DAB/NiCl2 may be somewhat more sensitive" can be used with all membrane types... 

Oxidation effects are observed in both films, but it seems that the oxidation products formed in the thin film are different. This may be a result of the differences between the orientation of the molecules in the film surface in the two types of sample. 

Many other degradation mechanisms (which are not described here) have been proposed by Isbell and Frush104 in order to account for the various oxidation products formed from carbohydrates by the action of H202. 

In addition to their use in combination with other antioxidants as melt stabilisers, phosphites are also used to reduce discoloration of polymer melts [37, 39, 40, 41, 42]. Using the phosphite Ultranox U-626 with tocopherol at a 2 1 w/w ratio, respectively, has resulted in a considerable colour reduction in the polymer (Fig. 5a-inset) [33]. This has also led to a 30% reduction in the total oxidation products formed in the polymer with only three products formed trimers, tocoquinone and aldehydes. This significant reduction in product formation results in an excellent retention of tocopherol in the polymer of over 95%. The preservation of the initial tocopherol con-... 

Harada, Y. and Inoko, A. (1977) The oxidation products formed from soil organic matter by hydrogen peroxide treatment. Soil Sci. Plant Nutr., 23, 513-521. 

This equation should be valid for most natural waters. In our future studies we plan to examine the oxidation products formed as a function of temperature and ionic strength. These measurements will hopefully lead to a better understanding of the mechanism of the oxidation. 

These reagents have a number of drawbacks. First of all, they are toxic especially via contact with skin. The LD50 (dermal, rat) of DCC is 71 mg kg. This should always be considered if the reaction is used for the preparation of materials for biological applications. Moreover, the N.N -dialkylurea formed during the reaction is hard to remove from the polymer except for preparation in DMF and DMSO, where it can be filtered off. In case of esterification of polysaccharides in DMSO in the presence of these reagents, oxidation of hydroxyl functions may occur due to a Moffatt type reaction (Fig. 25, [188]). The oxidation products formed can be detected with the aid of 2,4-dinitrophenylhydrazine, e.g. in case of the conversion of dextran with DCC in DMSO [189],... 

Figure 6 shows that the amount of reduction taking place depends upon the amount of oxidation that occurred initially at Ei= 1.000 volt. To help evaluate electron transfer, double potential step chronoamperometry was employed (Figure 10). In each instance the potential was stepped from to E2 +1.000 volt at the instant the cell was engaged. Initial oxidation proceeded for 25 seconds after which the potential stepped back to the starting potential E. In the short time of the experiment it was assumed that diffusion effects were minimal and the reduction at Ef acted on the oxidized product formed at E2 until it was consumed.

Prosthetic heme modification also occurs in some instances with the two-electron oxidation products formed by peroxidases when they oxidize halide and pseudohalide ions. Thus, the oxidation of bromide by HRP results in the addition of HOBr to one or both of the heme vinyl groups (Fig. 5.11) [62], Similar reactions are... 

The results obtained with methyl alcohol can be summed up) as follows Hydrogen bring evolved, the oxidation products formed are ... 

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