Oxidations of Alcohols, Diols, and Ketones with Fluorine

Oxidations of Alcohols, Diols, and Ketones with Fluorine 

For some oxidations, toxic heavy metal oxidants are used [128]. This can be circumvented by use of microreactor technology due to safe handling of elemental fluorine, vhich can be used to mediate oxidation reactions [129]. This is possible in a direct vay via fluorine introduction into the substrate and subsequent replacement by an oxygen moiety. In an indirect manner, intermediate oxygen transfer reagents such as HOF MeCN can be generated by reaction of aqueous acetonitrile with elemental fluorine, which then attack the substrate. The only byproduct is hydrogen fluoride, which could be recycled by electrolysis. 

The oxidation of cyclohexanol to cyclohexanone with fluorine and aqueous acetonitrile was performed in a single-channel microreactor operated under annular flow at room temperature. A conversion of 84% and a selectivity of 74% was observed [129]. In a similar way, diols such as oxidation of 1,2-cydohexandiol were partly or fully oxidized. A total of 53% selectivity to the mono-oxidation product was obtained at a conversion of 87% the di-oxidation product was obtained with 30% yield. 

The Baeyer-Villiger oxidation of cyclohexanone to the seven-membered lactone used aqueous formic acid (5% water) as medium and a 60% conversion at 88% selectivity was found [129]. 

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Direct fluorination of aliphatics and non-C moieties Direct fluorination of benzenoid aromatics Direct fluorination of heterocyclic aromatics Oxidations of alcohols, diols and ketones with fluorine Photo-oxidation of a-terpinene and cyclopentadiene Oxidation of benzyl alcohol to benzaldehyde Homogeneously catalyzed oxidation of butyraldehyde Oxidation of sulfite to sulfate Photochlorination of aromatic isocyanates... 

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