Thallium sulfate ketones

Symmetrical and unsymmetrical benzoins have been rapidly oxidized to benzils in high yields using solid reagent systems, copper(II) sulfate-alumina [105] or Oxone-wet alumina [105, 106] under the influence of microwaves (Scheme 6.32). Conventionally, the oxidative transformation of a-hydroxy ketones to 1,2-diketones is accomplished by reagents such as nitric acid, Fehling s solution, thallium(III) nitrate (TTN), ytterbium(III) nitrate, ammonium chlorochromate-alumina and dayfen. In addition to the extended reaction time, most of these processes suffer from drawbacks such as the use of corrosive acids and toxic metals that generate undesirable waste products. 

Sulfonation. Sulfonation is a common reaction with dialkyl sulfates, either by slow decomposition on heating with the release of S03 or by attack at the sulfur end of the O—S bond (63). Reaction products are usually the dimethyl ether, methanol, sulfonic acid, and methyl sulfonates, corresponding to both routes. Reactive aromatics are commonly those with higher reactivity to electrophilic substitution at temperatures > 100° C. Thphenylamine, diphenylmethylamine, anisole, and diphenyl ether exhibit ring sulfonation at 150—160°C, 140°C, 155—160°C, and 180—190°C, respectively, but diphenyl ketone and benzyl methyl ether do not react up to 190°C. Diphenyl amine methylates and then sulfonates. Catalysis of sulfonation of anthraquinone by dimethyl sulfate occurs with thallium(III) oxide or mercury(II) oxide at 170°C. Alkyl interchange also gives sulfation. 

Thallium(III) sulfate can effect a similar a-hydroxylation of straight chain saturated ketones. The vigorous conditions employed together with the apparently limited substrate effectiveness suggests that the procedure will find little synthetic application. 

ETHERS Antimony(V) fluoride. Hexamethylphosphorus triamide. Tetra-n-butyl hydrogen sulfate. Thallium(I) ethoxide. Triphenylphosphine-Diethyl azodicarboxylate. ETHYL KETONES Sodium tetracarbonylferratefll). 

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