Oxidation by Solids. I. Oxidation of Selected Alcohols by Manganese Dioxide

Abstract

It has been found that the rates of oxidation of a variety of phenylcarbinols by manganese dioxide in benzene can be readily followed by noting the rate at which the by-product water distills into a Dean-Stark trap. The aldehydes and ketones produced are obtained in high yields and close to the theoretical volume of water is collected. The effects of changes in structure of the alcohols on their rates of oxidation are consistent with the proposal that the reaction proceeds via free radical intermediates. Aliphatic alcohols underwent oxidation much more slowly and in much lower yields than did the phenylcarbinols.

New Reagent, Manganese Dioxide Supported on Kieselguhr, for Effective Oxidation of Benzoins

“…[35] To the best of our knowledge, so far there have been only a few reports about the use of manganese dioxide for the oxidation of benzoins to benzils, for instance, with solid manganese dioxide [10,11,30] and with supported manganese dioxide reagent, [23] almost all of which are carried out under heterogeneous conditions at reflux.…”

“…[1][2][3][4][5][6] The oxidation of benzoins has been accomplished by several oxidative reagents, such as pyridinium fluorochromate, [7] nitric acid, [8] Fehling's solution, [8] ammonium nitrate-copper acetate, [9] manganese dioxide, [10,11] thallium nitrate, [12,13] nickel acetate, [14] lanthanum nitrate, [15] ferric nitrate-clay, [16] ammonium chlorochromate-alumina, [17] ferric chloride, [18] bismuth(III) nitrate-copper(II) acetate, [19] zeolite, [20] H 3þn PMo 12-n V n O 40 , [21] ferric oxide-aluminum oxide, [22] manganese dioxide-silica, [23] ferric nitrate-silica, [24] bismuth(III) nitrate-silica, [25] potassium iodide, [26] triarylstibanes, [27] alumina, [28] ferric nitrate-graphite, [29] manganese dioxide under viscous conditions, [30] chromium trioxide-kieselguhr, [31] ferric nitrate-kieselguhr, [32] chromium trioxide-kieselguhr under viscous conditions, [33] and chromium trioxide in dimethyl sulfoxide. [34] Although many diverse methods are available for this oxidation, convenient and mild procedures are important objectives of current relevance.…”

Three new Glutarimide Alkaloids fromCroton Cuneatus

“…In accordance, the signals for C-13 and C-15 were shifted with respect to 4 (Table I). Lastly, treatment of 1 or 2 with manganese dioxide [17] afforded julocrotone (3). Cytotoxicity of 1-6 was studied against the following cancer cells types: MCF-7 (human breast carcinoma), X-17, Hep-G2, Skhep, LoVo, and normal human fibroblasts.…”

Preparation of 1,10-Dimethyl-benzo[c]cinnolines by Photochemical Cyclodehydrogenation of Azobenzenes

“…[14]: 0.1 g (0.4 mmol) commercial 2-bromo-5-tri¯uoromethyl-aniline were dissolved in benzene and re¯uxed with 1 g of freshly prepared and activated MnO 2 [15,16] General procedure for the photocyclodehydrogenation of azobenzenes 500 mg of azobenzene were added to a mixture of 1.8 l of absolute 1,2-dichloroethane and 6 ml of SnCl 4 (Aldrich). The solution was re¯uxed for 3 h under anhydrous conditions and irradiated at ambient temperature (22±25 C) for 45 h with a high-pressure mercury UV lamp (125 W).…”