Oxidation manganese dioxide, active

Econocat A process for deodorizing gases by catalytic oxidation over manganese dioxide activated with other metals. Developed and sold by Cortaulds Engineering. 

Potassium chlorate begins to decompose at about 70 0 by the catalytic action of metal oxides manganese dioxide, copper oxides etc. produce oxygen. The reaction actively progresses over 100 C. FeClj, CUCI2, Cr Oj and KiCriOy also promote the reaction. 

The pre-1817 experiments of Davy and Erman," followed by those of Fletcher," had shown that coal gas could ignite over platinum or hot iron wire at low temperatures gwiagflameless combustion. In 1902 the work was continued by Bone," " and during the 1914-1918 war several oxides were identified that promoted combustion at temperatures below 20°C. These included copper oxide, manganese dioxide, silver oxide, and cobalt oxide, as well as palladium metal. Mixed oxides were even more active, particularly if a promoter such as ceria was included. 

Nickel peroxide is a solid, insoluble oxidant prepared by reaction of nickel (II) salts with hypochlorite or ozone in aqueous alkaline solution. This reagent when used in nonpolar medium is similar to, but more reactive than, activated manganese dioxide in selectively oxidizing allylic or acetylenic alcohols. It also reacts rapidly with amines, phenols, hydrazones and sulfides so that selective oxidation of allylic alcohols in the presence of these functionalities may not be possible. In basic media the oxidizing power of nickel peroxide is increased and saturated primary alcohols can be oxidized directly to carboxylic acids. In the presence of ammonia at —20°, primary allylic alcohols give amides while at elevated temperatures nitriles are formed. At elevated temperatures efficient cleavage of a-glycols, a-ketols... 

In acidic electrolytes only lead, because it forms passive layers on the active surfaces, has proven sufficiently chemically stable to produce durable storage batteries. In contrast, in alkaline medium there are several substances basically suitable as electrode materials nickel hydroxide, silver oxide, and manganese dioxide as positive active materials may be combined with zinc, cadmium, iron, or metal hydrides. In each case potassium hydroxide is the electrolyte, at a concentration — depending on battery systems and application — in the range of 1.15 - 1,45 gem"3. Several elec-... 

Oxidation of di-n-butyl sulphide with activated manganese dioxide in light petroleum gave di-n-butyl sulphoxide exclusively126. However, the reaction was very slow at room temperature. This reagent is also suitable for oxidation of diallyl sulphides although, after 76 h, diallyl sulphoxide was isolated in 13% yield only. 

Manganese dioxide has been nsed to carry out a range of chemical oxidations, and is the reagent of choice for the oxidation of allylic alcohols (Hndlicky 1990). There are several methods for its preparation that may acconnt for differences in its activity. Although it has seldom been exploited for the oxidation of contaminants, two widely different applications have been described ... 

Rather than natural ores as in Leclanche batteries, electrolytic manganese dioxide (EMD), which is produced by anodic oxidation of Mn ions at graphite electrodes in solutions of manganese salts, is used as the active material for the positive... 

A reverse reaction, i.e. oxidation of -hydroxysulphoxides to -ketosulphoxides, can be performed using active manganese dioxide ... 

The violent decomposition observed on adding charcoal to cone, hydrogen peroxide is mainly owing to catalysis by metallic impurities present and the active surface of the charcoal, rather than to direct oxidation of the carbon [1], Charcoal mixed with a trace of manganese dioxide ignites immediately on contact with cone, peroxide [2],... 

The oxidation of a thiazolidine derivative to the corresponding thiazole using activated manganese dioxide in dichloromethane at 100 °C is shown in Scheme 6.100. Further manipulation of this molecule led to dimethyl sulfomycinamate, a methano-lysis product of the thiopeptide antibiotic sulfomycin I [203]. 

Some years later, Miller and others (1996) described a modified TEAC assay that is able to determine the antioxidant activity of carotenoids. In the improved version, ABTS,+, the oxidant, is generated by oxidation of 2,2 -azinobis(3-ethylbenzothiazoline-6-sulfonic acid)(ABTS2 ) with manganese dioxide. A similar approach was described by Re and others (1999) in which ABTS was oxidized with potassium persulfate (Fig. 10.2), this version of the TEAC assay is applicable to both water soluble and lipophilic antioxidants (Re and others 1999 Pellegrini and others 1999). 

This photoaffinity labelling analogue of all-fraws-retinal, 95b, has been tritium labelled80 by reduction of unlabelled aldehyde 95a with [3H]-NaBH4 and subsequent oxidation of the obtained tritium-labelled retinol with activated manganese dioxide. The product 95b (specific activity 38.3 mCimmol-1) has been isolated by preparative TLC (equation 36). 

Carbon, activated Chlorates Calcium hypochlorite, all oxidizing agents, unsaturated oils Ammonium salts, acids, metal powders, sulfur, finely divided organic or combustible materials, cyanides, metal sulfides, manganese dioxide, sulfur dioxide, organic acids... 

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