Alcohols, oxidizing reagents liquids

Various solid-supported perruthenate reagents have been designed for the oxidation of alcohols.Solid-supported NMO has also been used. A number of perruthenate systems employing O2 as the terminal oxidant have also been reported. The use of ionic liquids based upon substituted imidazolium cations as alternative solvent media for the selective oxidation of alcohols to aldehydes and ketones has also been investigated. ... 

Either amine oxides (usually NMO) [11,26] or potassium ferricyanide/potassium carbonate [12,35] are used as cooxidants for catalytic AD. The choice of oxidant carries with it the choice of solvent for the reaction, and the details of the catalytic cycle appear to be quite different depending on which oxidant-solvent combination is used. When potassium fenicyanide/potas-sium carbonate is used as the oxidant, the solvent used for the reaction is a 1 1 mixture of i-butyl alcohol and water [35,36], This solvent mixture, normally miscible, separates into two liquid phases upon addition of the inorganic reagents. The sequence of reactions summarized below in Eqs, 6D.1-6D.5 has been postulated as occurring under these conditions. This reaction sequence is further illustrated in the reaction cycle shown in Scheme 6D.2, which also emphasizes the role of the two-phase solvent system. 

In contrast, if a single aqueous liquid phase is used, and if the aldehyde product has a tendency to be hydrated, the reaction proceeds smoothly to the carboxylic acid salt (413,414). It is believed that the RC(OH)2 hydration product of the aldehyde is the actual reagent. This reaction is highly useful for the selective oxidation of primary alcohol groups in sugars such as methyl-a-D-glucopyranoside to the uronic salt ... 

A very mild oxidation procedure that tolerates a variety of other functional groups is the oxidation of alcohols to aldehydes and ketones by the dimethyl sulfoxide (DMSO). A DMSO solution of the alcohol is treated with one of the several electrophilic dehydrating reagents. The alcohol is oxidized to the aldehyde or ketone and DMSO is reduced to dimethyl sulfide (DMS), which is a volatile liquid (b.p. 37°C). Since pure DMSO freezes at 18°C and an oxidation reaction is carried out at —50°C or lower, a co-solvent such as methylene chloride or THF (tetrahydrofuran) is needed. 

Anatase is much more active than rutile in the liquid-phase photooxidation of 2-propanol, and the observed reactivity compared well with that of gaseous alcohol on platinized titania [106a]. Because most early studies employed the alcohol as a sacrificial reagent for the photochemical production of hydrogen, the organic product was often not analyzed and little effort was devoted to the selective activation of alcohols in the presence of other functional groups. In the oxidation of car-... 

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