Organic synthesis in water carbon dioxide microemulsions

Nucleophilic substitution reactions were performed in H2O/CO2 (w/c) microemulsions formed with an anionic perfluoropolyether ammonium carboxylate (PFPE COO-NH4+) surfactant. These reactions between hydrophilic nucleophiles and hydrophobic substrates were accomplished in an environmentally benign microemulsion without requiring toxic organic solvents or phase transfer catalysts. For the synthesis of benzyl bromide from benzyl chloride and KBr, the yield was an order of magnitude higher in w/c microemulsions versus conventional water-in-oil (w/o) microemulsions. Benzoyl chloride and p-nitrophenyl chloroformate were hydrolyzed in w/c microemulsions with rate constants an order of magnitude faster than those in w/o microemulsions.