Reactivity of trihexyl(tetradecyl)phosphonium chloride, a room-temperature phosphonium ionic liquid

Trihexyl(tetradecyl)phosphonium chloride 1, a room-temperature ionic liquid, readily undergoes deuterium isotope exchange reaction in deuterated solvents. Under basic conditions, ionic liquid 1 was reactive and 50% deuterium exchanged on all four P–CH₂ methylene groups in 9 h at ambient temperature, 30 min at 50 °C, or 12 min at 65 °C. In addition, ionic liquid 1 reacted with sodium salts of substituted benzoates apparently through the direct S_N2 carboxylate alkylation to form esters 2 and the resulting esters further converted, via Wittig reaction, to finally afford aryl ketones 4.