Mass spectrometry. Comparison of the electron impact and chemical ionization fragmentations of 8,9-dehydro-2-adamantanol and 2-exo-protoadamantenol

Abstract

10%), 229 (7%); nmr 1.12 (s, 3 H, C-4 CH3), no resonance for the C-3 proton. The compound showed a single component on analysis by tic and glc (on four systems noted above).The less polar major component (19.0 mg) on tic showed a mass spectrum which was very similar to that of [3a,4d-2H2]-4a-methylcholest-5-en-3d-ol (V) with additional ions at 399 (90%) and 366 (3%). The nmr spectrum showed the presence of signals 4.95 (m), 5.62 (m), and 8.43 in addition to the resonances seen in the spectrum of III. The spectrum showed no absorbance at 3.71 (C-3 H) or at 3.90 seen in the spectrum of the less polar component obtained as a by-product in the synthesis of IV.

Nitrous oxide as reagent gas for positive ion chemical ionization mass spectrometry

“…This difference is readily explained in terms of a greater ease of abstraction of a tertiary than of a secondary hydroxyl group and of a strong preference for abstraction of the hydrogen of the substituted carbon in preference to all others. These observations for the reactions of NO"1" are consistent with early conclusions from the NO Cl spectra of alcohols (19,20). Dissociative charge transfer from N20+ to 1-adamantanol produces C6H70+, 18%, the major ion in the El spectrum.…”

Comparison of positive ions formed in nickel-63 and corona discharge ion sources using nitrogen, argon, isobutane, ammonia and nitric oxide as reagents in atmospheric pressure ionization mass spectrometry

“…Reactions of NO+ Ions. The use of NO+ ions in conventional Cl mass spectrometry has been recommended as a means of identifying certain functional groups (18)(19)(20)(21)(22). For example, hydride abstraction from a secondary alcohol leads to (M-H)+:…”

Stable carbocations. 212. On the structure of cyclopropylcarbinyl and cyclobutyl cations. 8,9-Dehydro-2-adamantyl and 2,5-dehydro-4-protoadamantyl cations

“…Of course, these data do not uniquely define the structure of ion 17. The structure assignment for 17 follows from the observation that the and 13C NMR spectra of 17 are strikingly similar to the corresponding spectra of the 2bicyclo[3.2.1]oct-3-enyl cation (18).11 18The unexpected rearrangement of 12 to 17 can be rationalized as proceeding by the initial formation of the 2-protoadamantenyl cation (19) which undergoes migration of the C-l to C-10 bond in 19 to give the 2-isotwistenyl cation (20). Acid-catalyzed solvolysis reactions of 8,9-dehydro-2-adam-antyl17 and 2-exo-substituted protoadamantyl23 derivatives which parallel 12 -19 and 19 -20, respectively, have been reported.…”