Manganese oxide, oxidizing phenolic acids

Oxidation of phenolic acids by soil iron and manganese oxides. Soil Sci. Soc. 

Ukrainczyk, L. and M.B. McBride. 1992. Oxidation of phenol in acidic aqueous suspensions of manganese oxides. Clays Clay Miner. 40, 157-166. 

Quinones can he prepared hy the oxidation of phenols, dihydroxy-henzenes, dimethoxyhenzenes and anilines. For example, 1,4-dihydroxy-henzene (hydroquinone) can he oxidized in good yield using sodium chlorate in dilute sulfuric acid in the presence of vanadium pentoxide and also hy manganese dioxide and sulfuric acid and hy chromic acid. Other reagents which convert hydroquinones to quinones include Fremy s salt [potassium nitrosodisulfonate, (KS03)2N0] and cerium(IV) ammonium nitrate [CAN, Ce(NH4)2(N03)J. 

Manganese dioxide oxidized five common soil phenolic acids—vanillic (32), syrin-gic (33), ju-coumaric (34), ferulic (30), and sinapic (29) acids — although p-hydroxybenzoic acid (35) was inert (Lehmann et al., 1987). Salicylic acid (31), although strongly held by manganese oxide, was resistant to oxidation (McBride, 1987), as were several aliphatic acids such as citric, lactic, pyruvic and tartaric acids (Stone and Morgan, 1984). 

Lehmann RG, Cheng HH, Harsh JB (1987) Oxidation of phenolic acids by soil iron and manganese oxides. SoU Sci Soc Am J 51 352-356... 

Biochemical Routes. Enzymatic oxidation of benzene or phenol leading to dilute solution of dihydroxybenzenes is known (62). Glucose can be converted into quinic acid [77-95-2] by fermentation. The quinic acid is subsequently oxidized to hydroquinone and -benzoquinone with manganese dioxide (63). 

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... 

The permanganate oxidation of phenols is complicated by the intervention of lower oxidation states of manganese, (c/. the oxidation of toluene, p. 298). For example, the oxidation of 2,6-dinitrophenol in weakly acidic solution displays an induction period, following second-order kinetics thereafter. However, addition of potassium fluoride inhibits reaction almost completely, but manganous ions strongly accelerate it. 

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