Figure 5. Deuterium exchange on the methoxy carbon of volatile anesthetics catalyzed by strong base. Proton abstraction catalyzed by either (A) potassium or (B) sodium deuteroxide in deuterium oxide was measured by incorporation of deuterium into the anesthetic molecule. Equimolar anesthetic concentrations were used. Results are mean +/− SD (n = 3 for potassium deuteroxide, n = 5 for sodium deuteroxide). No deuterium incorporation was observed with barium deuteroxide and any anesthetic (not shown). Results indicate the relative ease of methoxy proton abstraction is enflurane > desflurane > isoflurane >or= to sevoflurane = methoxyflurane = 0.