Synthesis of carboxylates

The direct carboxylation of an organic substrate to produce carboxylic acids and their derivatives is an interesting application of CO2. Such reactions have been attempted using 'residual' or 'waste' ionizing radiations that promote CO2 fixation at room temperature. Applications of this technology include the direct synthesis of carboxylates from hydrocarbons and the polymerization in or with supercritical CO2 (sc-CO2) (Fujita et al., 1994, 1996). The carboxylation of active C-H bonds has been achieved with 100% selectivity at room temperature using carboxylated ionic liquids (Aresta et al., 2003e).

Specialty chemicals, having a small market (several thousand tonnes per year) and high value, such as pharmaceuticals, amino acids and asymmetric compounds, tend to be synthesized through complex routes, and produce a large amount of waste, often 50 times their mass. As such, they may represent an attractive application of CO2-based electrochemical syntheses (Dunach et al., 2001; Augustinski et al., 2003).

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