Figure 6. Deuterium exchange on the ethyl carbon (isopropyl carbon for sevoflurane) of volatile anesthetics catalyzed by strong base. Proton abstraction catalyzed by either (A) potassium or (B) sodium deuteroxide was measured by deuterium incorporation into the anesthetic molecule. Equimolar anesthetic concentrations were used. Mean values are shown (n = 3 for potassium deuteroxide, n = 5 for sodium deuteroxide); SD is omitted for clarity. No deuterium incorporation was observed with barium deuteroxide and any anesthetic (not shown). Symbols denote enflurane ([white circle]), desflurane ([white diamond]), isoflurane ([white triangle]), methoxyflurane ([white square]), sevoflurane (X), and halothane ([inverted triangle]). Results indicate that ethyl proton abstraction is facile from all anesthetics (less so with desflurane).