A Nitric Acid-Assisted Carbon-Catalyzed Oxidation System with Nitroxide Radical Cocatalysts as an Efficient and Green Protocol for Selective Aerobic Oxidation of Alcohols

Authors

  • Yongbo Kuang,

    1. Department of Organic and Polymeric Materials, Tokyo Institute of Technology, Meguro-ku, Tokyo 152-8552, Japan, Fax: (+81)-3-5734-2875; phone: (+81)-3-5734-2433
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  • Hodaka Rokubuichi,

    1. Department of Organic and Polymeric Materials, Tokyo Institute of Technology, Meguro-ku, Tokyo 152-8552, Japan, Fax: (+81)-3-5734-2875; phone: (+81)-3-5734-2433
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  • Yuta Nabae,

    1. Department of Organic and Polymeric Materials, Tokyo Institute of Technology, Meguro-ku, Tokyo 152-8552, Japan, Fax: (+81)-3-5734-2875; phone: (+81)-3-5734-2433
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  • Teruaki Hayakawa,

    1. Department of Organic and Polymeric Materials, Tokyo Institute of Technology, Meguro-ku, Tokyo 152-8552, Japan, Fax: (+81)-3-5734-2875; phone: (+81)-3-5734-2433
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  • Masa-aki Kakimoto

    1. Department of Organic and Polymeric Materials, Tokyo Institute of Technology, Meguro-ku, Tokyo 152-8552, Japan, Fax: (+81)-3-5734-2875; phone: (+81)-3-5734-2433
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Abstract

The incorporation of nitroxide radicals into a nitric acid-assisted carbon-catalyzed oxidation system (NACOS) afforded a highly efficient, widely applicable, non-metallic approach for the selective aerobic oxidations of alcohols. Without any solvent, this novel protocol has the ability to oxidize various primary alcohols to their corresponding aldehydes with selectvities as high as 99% at full conversions, with only 0.1 mol% of nitroxide radicals and <4.5 wt% of activated carbon under mild conditions (temperatures as low as 50 °C and atmospheric pressure). The performances of several stable nitroxide radicals have been compared. The effects of nitric acid concentration, activated carbon loading, and temperature have been studied for the oxidation of benzyl alcohol. The enhanced NACOS represents a greener and more efficient fundamental chemical process, due to its use of molecular oxygen as an oxidant, and its solvent-free nature.

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