Abstract: | In the 70 e V electron impact mass spectra of a series of alkyldiphenylphosphine oxides (R?2PO, R = Me, Et, n-Pr, i-Pr, n-Bu, i-Bu, t-Bu, neopentyl, n-decyl), molecular ions of low abundance are observed and M + H]+ ions are formed to a small extent at high sample pressures. The major ions include ?2PO]+, ?2POH]+; ?2CH2PO]+ and ?2CH2POH]+ which are formed by rearrangement and cleavage processes. The chemical ionization mass spectra obtained with methane and isobutane reagents consist of M + H]+ ions. The proton affinity of R?2PO was found to be 219 ± 2.5 kcal mol?1. |