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Keywords:

density functional calculations, diradicals, femtochemistry, hydrogen transfer, norrish reactions, alpha-cleavage, states, dissociation, abstraction, activation, acetone, ketones, atom, Science & Technology, Physical Sciences, Chemistry, Multidisciplinary, Chemistry, Norrish reactions, ALPHA-CLEAVAGE, STATES, DISSOCIATION, ABSTRACTION, ACTIVATION, ACETONE, KETONES, ATOM, 03 Chemical Sciences, Organic Chemistry, 34 Chemical sciences

Abstract:

Norrish type-II and McLafferty rearrangements, which both involve an intramolecular transfer of a gamma H atom, can be differentiated on the femtosecond time scale. The McLafferty rearrangement results in ion fragmentation of the parent ketone, whereas the Norrish type-II reaction leads to a diradical species, which then either cyclizes or fragments (see scheme). For Norrish type-II reactions, the reaction time for the transfer of the hydrogen atom is within 70 - 90 fs, and the lifetime of the diradical intermediate is in the range of 400 - 700 ps at the total energy studied.