β Scribed by Guy Bouchoux; Robert Flammang; Pascale Jaudon; Odile Lefevre
No coin nor oath required. For personal study only.
Mass spectra of the four isomeric ethylbutyl ketones, C~2~H~5~COβnβC~4~H~9~ (1), C~2~H~5~COβisoβC~4~H~9~ (2), C~2~H~5~COβsecβC~4~H~9~ (3) and C~2~H~5~ COβtβC~4~H~9~ (4), are reported. The structure of the fragment ions produced from precursors of both high and low internal energy were identified by collision experiments in a sixβsector mass spectrometer. Metastable molecular ions 1^+Λ^ and 2^+Λ^ behave identically in expelling CH~3~^Λ^, C~3~H~6~ and C~2~H~5~^Λ^ to produce the same fragment ions: [C~2~H~5~C(OH)CHCHCH~3~]^+^, [C~2~H~5~C(OH)ο£ΎCH~2~]^+Λ^ and a mixture of [CHOHCHCHC~2~H~5~]^+^ and [CHOHCHC(CH~3~)~2~]^+^, respectively. The key isomerization step between 1^+Λ^ and 2^+Λ^ is a 1,2βenolβolefin shift. Metastable molecular ions 3^+Λ^ and 4^+Λ^ give essentially ethene and ethyl losses, respectively; the fragment ions are [C~2~H~5~C(OH)CHCH~3~]^+Λ^ and [tβC~4~H~9~CO]^+^. Ketoβenol isomerization also occurs to a significant extent for ions 1^+Λ^ and 2^+Λ^ and 3^+Λ^. In contrast, 1,2β or 1,3βethylhydroxycarbene migrations are only marginal processes.
π SIMILAR VOLUMES