Ammonium molybdate secondary alcohols

Other molybdenum complexes able to catalyze the selective oxidation of secondary alcohols are ammonium molybdate in the presence of H202,30 benzyltrimethylammonium tetrabromooxomolybdate in the presence of r-BuOOH31 and molybdenum hexacarbonyl in the presence of catalytic cetylpyridinium chloride and stoichiometric t-BuOOH.32... 

Oxidations.1 Secondary alcohols are oxidized to ketones in moderate to high yield by hydrogen peroxide (30%) in the presence of the ammonium molybdate, potassium carbonate, and tetra-/i-butylammonium chloride in THF at 20°. Epoxidation is suppressed by the presence of potassium carbonate, which also accelerates the reaction. Primary alcohols are not oxidized under these conditions. 

Several procedures for this chemoselective oxidation utilize molybdenum-based catalysts, with either hydrogen peroxide or r-butyl hydroperoxide as the stoichiometric oxidant. These include ammonium molybdate in the presence of a ph e transfer reagent and hydrogen peroxide, which with pH control (potassium carbonate) will selectively oxidize a secondary alcohol in the presence of a primary alcohol without oxidizing alkenes. In addition hindered alcohols are oxidized in preference to less hindered ones (Scheme 18). 

Under such conditions secondary alcohols rarely afford homogeneous products, as the aldehydes expected as primary products too readily undergo further reactions. Exceptionally, a preparatively useful application has been found in the degradation of aldose diethyl dithioacetals these are oxidized by organic peracids or by hydrogen peroxide in the presence of ammonium molybdate to the disulfones which are cleaved at secondary alcohol groups by dilute ammonia solution.78,79 This method has been applied to acetyl-... 

After shaking for 5 min a few drops of a 1% ammonium molybdate solution are added to the reaction mixture, which is then acidified with 2NH2SO4. After dissolution of the solid alkali the mixture is extracted with chloroform. A violet color of the chloroform layer proves the presence of a primary or a secondary alcohol. 

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