Hydrogen‐deuterium exchange reactions of cis ‐ and trans ‐cyclopropane derivatives with D 2 O and CD 3 OD in the gas phase

Gas‐phase hydrogen‐deuterium (H/D) exchange reactions involving four isomeric cyclopropane derivatives were investigated under chemical ionization (CI) conditions, using D 2 O and CD 3 OD as reagent gases. There are abundant ions at [M + 1] + , [M + 2] + and [M + 3] + in the D 2 O and CD 3 OD positive‐ion CI mass spectra of the two isomer pairs 1, 2 and 3, 4. Their CI mass spectra are identical with each pair, and so are the collision‐induced dissociation (CID) spectra of ions [M + 1] + , [M + 2] + and [M + 3] + of each of the two isomer pairs. The CID spectra of [M + 1] + ions indicate that they have common D/H exchange reactions within each pair, which take place between molecular ions and deuterium‐labeling reagents to form the [M − H + D] + ions. Those of their [M + 2] + ions show that they have common D/H exchange reactions within each pair, which form the [M d1  + H] + ions. Those of their [M + 3] + ions show that they have common D/H exchange reactions within each pair, which take place between the [M d1 ] and deuterium‐labeling reagents to produce [M d2  + H] + for the isomer pair 1, 2 and [M d1  + D] + for the isomer pair 3, 4. The number and position, and active order of the active hydrogen atoms of the isomer pairs 1, 2 and 3, 4 were determined. Copyright © 2000 John Wiley & Sons, Ltd.