Phase-transfer catalysis in the oxidation of C₆₀ and C₇₀ fullerene with KMnO₄ and crown ether

ABSTRACT

The KMnO₄ oxidation reaction of C₆₀ or C₇₀ fullerenes in benzene solution proceeds smoothly and almost quantitatively in presence of the crown ether 18-crown-6 as phase-transfer agent. The oxidation reaction was followed spectrophotometrically from the early stages to the completion. Essentially fullerenols or polyhydroxylated fullerenes were produced as confirmed also by FT-IR spectroscopy. The resulting degree of hydroxylation of both C₆₀ and C₇₀ was determined as C₆₀(OH)₂₈ and C₇₀(OH)₂₆. As secondary structures, also epoxide and carboxylic groups were detected.

KEYWORDS:

• Fullerenes
• fullerenols
• crown ether
• potassium permanganate
• phase-transfer catalysis
• oxidation

Acknowledgments

We acknowledge support provided by the Spanish Ministry of Economy and Competitiveness (MINECO) under grant AYA-2014-58082-P.