Why does pivalaldehyde (trimethylacetaldehyde) unexpectedly seem more basic than 1-adamantanecarbaldehyde in the gas phase? FT-ICR and high-level ab initio studies.
Fourier transform ion cyclotron resonance spectroscopy (FT ICR) techniques, including collision-induced dissociation (CID) methodology, were applied to the study of the gas-phase protonation of pivalaldehyde (1) and 1-adamantanecarbaldehyde (2). A new synthetic method for 2 was developed. The experiments, together with a thorough computational study involving ab initio and density functional theory (DFT) calculations of high level, conclusively show that upon monoprotonation in the gas phase, compound 1 yields monoprotonated methyl isopropyl ketone 3. The mechanism of this gas-phase acid-catalyzed isomerization is different from that reported by Olah and Suryah Prakash for the reaction in solution. In the latter case, isomerization takes place through the diprotonation of 1.
Quintanilla
Esther
E
Instituto de Química Física Rocasolano, CSIC, C/Serrano 119, 28006 Madrid, Spain.
Dávalos
Juan Z
JZ
Abboud
José-Luis M
JL
Alcamí
Manuel
M
Cabildo
M Pilar
MP
Claramunt
Rosa M
RM
Elguero
José
J
Mó
Otilia
O
Yáñez
Manuel
M