Thallic acetate

The formation of a-acetoxyketones by oxidation of enamines with thallic acetate has been studied in detail (27) and found to be of preparative value (80 % yields) particularly in five- and six-membered-ring ketone derivatives. Enamines of linear or seven-membered-ring ketones were oxidized also, but at very much slower rates. Enamines of aldehydes with a-hydrogen substituents underwent self-eondensations during the oxidation reactions. Lead tetraacetate was less satisfactory as an oxidizing agent. 

Henry has examined in detail the oxidation of several olefins both by thallic perchlorate in an aqueous perchloric acid medium and by thallic acetate in aqueous acetic acid. The reaction displays mixed stoichiometry... 

The ultimate product of Hg(II) oxidation is cyclohexane-1,2-dione which is probably produced from 2-hydroxycyclohexanone. The oxidation by thallic perchlorate produces cyclopentanecarboxylic acid in 75 % yield this contrasts with the production of 2-acetoxycyclohexanone by thallic acetate . The mechanism favoured for the production of the carboxylic acid is... 

Mercuric acetate and thallic acetate have also been used for the oxidative cydiza-tion of vinylallenes (Eq. 13.24) [29]. Exposure of vinylallene 75 to stoichiometric mercuric acetate in acetic acid led to cydopentenone 76 in 75% yield. With thallium acetate as the oxidant, the yield of 76 was 60%. The presumed mechanism of the oxidative cyclization involves a Nazarov cyclization of acetoxymercury intermediate 77. 

Thallium (III) Compounds. Thallium (ITT) derivatives have been used extensively as oxidants in oiganic synthesis. In particular, thallic acetate and trifluoroacetate are extremely effective as electrophiles in oxythallation and thallation reactions. For example, ketones can be prepared from terminal acetylenes by means of Tl(OOCCH3)3 in acetic acid (oxythallation) (30) ... 

Acetate ion, however, complexes thallic ion about as well as chloride, and with aqueous thallic acetate there is not the complication of thalhc- and thallous-containing species precipitating as the reaction proceeds. Thallic acetate itself is unreactive towards ethylene, but if strong acid is added to the solution, the oxidation rate of ethylene increases. The values of K3 and K4 for the equilibria represented by Reactions 28 and 29 were determined by pH measurements (23). 

Diethylacetylene allowed to react with thallic acetate sesquihydrate in glacial acetic acid containing 4.5 moles acetic anhydride product. Y 87%. F. e. s. R. K. Sharma and N. H. Fellers, J. Organometal. Chem. 49, C 69 (1973). 

Thallic acetate and excess propionic acid heated with distillation of the resulting acetic acid, then refluxed under Ng a-propionoxypropionic acid. Y 88%. F. e. s. E. C. Taylor et al., Tetrah. Let. 1970, 5285. 

A soln. of phenylcyclopropane and thallic acetate in acetic acid heated 120 hrs. at 75° 1-phenyl-1,3-diacetoxypropane. Y 92%.—Thallic acetate is very... 

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