Methanol-hydrogen peroxide combination

The electrodeposition process can also be combined with an AAO template for the fabrication of a metal-embedded hollow nanotube structure, that is, Ni-embedded silica nanotubes, as demonstrated by Xu et al. [79]. The fabrication starts with the electrodeposition of multiple segments of Ag/Ni/Ag (3 pm/3 pm/ 3 pm) nanowires with a diameter of 300 nm on nanoporous AAO templates (Figure 13.7d). Subsequently, a hydrolysis reaction of tetraethyl orthosiUcate was performed for 2-5 h to coat a 70 nm thick silica layer. Then, Ag was selectively etched in a mixture (4 1 1) of methanol, hydrogen peroxide, and ammonia hydroxide to produce a hollow structure. Finally, Ag nanoparticles were functionalized on the surface by the reduction of Ag ions at 70 °C for 7 h in a composite solution of PVP (2.5xlO M in ethanol), silver nitrate (0.06 M), and ammonia hydroxide (0.12 M). The synthesized silica nanotubes exhibited a Ni-embedded hollow structure with Ag nanoparticles functionalized on the surface... 

ALTERNATE PROTOCOL 2 ENZYMATIC MEASUREMENT OF CHOLESTEROL Test combination kits for enzymatic determination of cholesterol in food are now commercially available. For the determination of total cholesterol, esterified cholesterol is hydrolyzed to free cholesterol and fatty acid under mild alkaline conditions. Cholesterol oxidase oxidizes free cholesterol to cholest-4-en-3-one to generate hydrogen peroxide, which further oxidizes methanol to formaldehyde. Formaldehyde then reacts with acetyl acetone in the presence of NH4+ ions to form yellow lutidine dye, which is subsequently determined spectrophotometric al 1 y. 

Epoxidation. The combination of hydrogen peroxide (30%) and the Vilsmeier reagent presumably affords the salt [(CH3)2N=CHOOH] + P02C12 (1). When I is generated in methanol in the presence of an olefin at —20°, trans-1,2-dichloro compounds are formed in high yield. If the reaction is conducted at —80° and in the presence of sodium carbonate, epoxides are formed in high yield. 

The Ru(II)/ROOH system can also be used to oxidize tertiary amines. The intermediate iminium ion is formed, as described earlier for secondary amines, and can be trapped by nucleophiles. Thus, the ruthenium-catalysed oxidation of tertiary amines with hydrogen peroxide in methanol can be performed to give the corresponding a-methoxyamines with high efficiency as illustrated in Fig. 24 [ 137]. Another example is the selective demethylation of tertiary amines in methanol with a combination of Ru(II) and H202, followed by hydrolysis of the intermediate a-methoxylated amines. For example, the methoxylation of N,N-dimethyl-p-toluidine followed by treatment with 2 N HC1 solution gave N-methyl-p-toluidine in 75% yield (Eq. 35) [137]. 

Oxidative cleavage of arenesulfonylhydrazones. The combination of hydrogen peroxide (30-50%) and potassium carbonate in methanol or dioxane is recommended for regeneration of both aldehydes and ketones from arenesulfonylhydrazones. Most of the known methods for this reaction are suitable only for... 

Two examples of low temperature, catalytic, methane oxidation by hydrogen peroxide should be included in this section. The first involves conversion to methanol using cis-[Ru(2,9-dimethyl-l,10-phenanthroline)(solvent)2](PF6)2 as the catalyst [39]. A ruthenium-oxo species has been proposed as the C-H activating species. In the second report, conversion of methane to methyl hydroperoxide is claimed [40]. The catalyst is a combination of [NBuJ V03 and pyrazine-2-carbox-ylic acid. While the mechanism is uncertain, the actual oxidant is believed to be dioxygen with HO derived from hydrogen peroxide acting as the initiator. 

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