The utility of organofluorine compounds across the chemical industries cannot be understated. This unique position in modern chemistry is derived from both the incredible thermodynamic and kinetic stability of the C-F bond. However, these same features have historically made the degradation of organofluorine compounds challenging, allowing fluorocarbons to persist in the environment for extended periods of time; several of which are bio-accumulative and toxic or highly potent greenhouse gases. To address this, the conversion of fluorocarbons into benign hydrocarbon products (hydrodefluorination, HDF) has received increasing focus over the past decades. While many of the existing catalytic HDF systems are efficient, many also suffer from the need for either high reaction temperatures/pressures or exotic and expensive reducing reagents to achieve high reactivity. Hydrogen (H2) would be the ideal reductant for HDF, as H2 is atom-economical, inexpensive, readily available, and can be formed by sustainable energy processes. Unfortunately, H2 is generally less reactive than many other hydrogen sources, and concomitant HF generation during catalysis can interfere with the overall HDF reaction. Addressing the concerns listed above, we recently designed a novel and practical approach to utilize of H2 in KOH/H2O media for catalytic HDF, mediated by Ru metal catalysts. In this study, a variety aryl-fluorocarbons and perfluorocarbons were observed to be rapidly defluorinated at low temperatures (<100�C) to generate hydrocarbon products. Additionally, alkyl fluorocarbons (such as CH2F2) could also be defluorinated at more forcing conditions, which is comparatively rare in the chemical literature. Utilization of basic media was determined to be key in our overall approach, as basic media: 1) enhances HDF with H2; and 2) provides an efficient fluoride trap, forming innocuous KF salt instead of HF.

Hydroxide-promoted catalytic hydrodefluorination by ruthenium in aqueous media

247th National Meeting (2014)

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