La&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;O&amp;lt;sub&amp;gt;3&amp;lt;/sub&amp;gt; Catalyzed Oxidation of Alcohols

Gowda, Ravikumar R.; Chakraborty, Debashis

doi:10.4236/ijoc.2011.12008

Cited by 5 publications

References 54 publications

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Solvent‐Less Organic Synthesis

Kaupp

2012

Kirk-Othmer Encyclopedia of Chemical Technology

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Solvent‐less reactions realize 100% yield of one product without involvement of any added solvent for reaction and workup. They occur in virtually all reaction types by proper choice of the states of aggregation and reaction technique. This article is subdivided into melting, kneading, dry milling, gas–solid reactions, and gas–liquid reactions. The choice depends on the crystal packing, melting points, and eutectic temperatures during a reaction. Temperature control is essential for achieving the full benefit of crystal packing or the maximal concentration in the absence of deactivating solvation. The reaction temperatures are decreased as a result of the most favorable kinetics that lead to complete conversions and mostly avoid catalysis. An additional advantage is the direct and perfect exclusion of moisture. A decreased reaction temperature often enables staying below the eutectic temperature, or allows for obtaining otherwise nonaccessible new products that directly crystallize without involving a liquid phase. If the yield is also quantitative with the product directly crystallizing from the melt, it may be easier to perform melt reactions with slight heating. The so‐called “solvent‐free” (rather than solvent‐less) reactions are mostly not quantitative and often not free of auxiliaries, which requires solvent‐consuming chromatography and separation of the auxiliary with usually difficult recovery (eg, catalysts or supports). The hype surrounding catalysis from “green chemistry” to perform reactions in “green‐solvents” or “solvent‐free” is counterproductive. Solvent‐less reactions without catalyst and with 100% yield of pure product are the better choice. It is therefore necessary to report the broad application and variability of solvent‐less techniques, for the sake of sustainability.

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Solvent‐Less Organic Synthesis

Kaupp

2012

Kirk-Othmer Encyclopedia of Chemical Technology

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Application and Mechanistic Studies of a Water‐Oxidation Catalyst in Alcohol Oxidation by Employing Oxygen‐Transfer Reagents

Verho

Dilenstam

Kärkäs

et al. 2012

Chemistry A European J

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By using a dimeric ruthenium complex in combination with tert-butyl hydrogen peroxide (TBHP) as stoichiometric oxidant, a mild and efficient protocol for the oxidation of secondary benzylic alcohols was obtained, thereby giving the corresponding ketones in high yields within 4 h. However, in the oxidation of aliphatic alcohols, the TBHP protocol suffered from low conversions owing to a competing Ru-catalyzed disproportionation of the oxidant. Gratifyingly, by switching to Oxone (2 KHSO(5)⋅KHSO(4)⋅K(2)SO(4) triple salt) as stoichiometric oxidant, a more efficient and robust system was obtained that allowed for the oxidation of a wide range of aliphatic and benzylic secondary alcohols, giving the corresponding ketones in excellent yields. The mechanism for these reactions is believed to involve a high-valent Ru(V)-oxo species. We provide support for such an intermediate by means of mechanistic studies.

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