76246-51-0Relevant academic research and scientific papers
Characterizaton of Five + Ion Structures. Fragmentation of the 2-Pentanone Molecular Ion
Laderoute, Keith R.,Zwinselman, Jan J.,Harrison, Alex. G.
, p. 25 - 33 (1985)
The + ions + (1), + (2), + (3), O>+ (4), and O>+ (5) have been characterized by their collision-induced dissociation (CID) mass spectra and charge stripping mass spectra.The ions 1-3 were prepared by gas phase protonation of the relevant carbonyl compounds while 4 and 5 were prepared by dissociative electron impact ionization of the appropriate carbonyl compounds.Only 2 and 3 give similar spectra and are difficult to distinguish from each other; the remaining ions can be readily characterized by either their CID mass spectra or their charge stripping mass spectra.The 2-pentanone molecular ion fragments by loss of the C(1) methyl and the C(5) methyl in the ratio 60:40 for metastable ions: at higher internal energies loss of the C(1) methyl becomes more favoured.Metastable ion characteristics, CID mass spectra and charge stripping mass spectra all show that loss of the C(1) methyl leads to formation of the acyl ion 4, while loss of the C(5) methyl leads to formation of protonated vinyl methyl ketone (1).These results are in agreement with the previously propossed potential energy diagram for the +. system.
CH-π interaction as an important driving force of host-guest complexation in apolar organic media. Binding of monools and acetylated compounds to resorcinol cyclic tetramer as studied by 1H NMR and circular dichroism spectroscopy
Kobayashi, Kenji,Asakawa, Yuji,Kikuchi, Yasuaki,Toi, Hiroo,Aoyama, Yasuhiro
, p. 2648 - 2653 (2007/10/02)
The CH-π interaction plays an important role in the complexation involving resorcinol cyclic tetramer 1 in chloroform. Thus, host 1 binds simple monools 4-10 via a cooperation of CH-π and hydrogen-bonding interactions, where the binding constants at 298 K (up to 13 M-1) increase with increasing chain lengths (from ethyl through propyl to butyl) as well as branching in the aliphatic moiety of the guests. In addition, the largest complexation-induced 1H NMR upfield shift for a bound guest occurs at the terminal methyl group, which must therefore be deeply incorporated in the aromatic cavity of the host. The complexes derived from chiral secondary alcohols 10-17 including terpenes and steroids exhibit induced circular dichroism as a result of guest-to-host chirality transfer which is mediated by the CH-π interaction. Borneol (14) having three methyl groups to allow a multipoint CH-π interaction forms a particularly stable complex (K = 54 M-1). The acetyl group in a guest is significantly complexation-promoting. This is primarily due to enhanced CH-π interaction involving the polarized C-H bonds of the acetyl group. The binding constants for selected guests are K = 35, 12, 4, and 1 M-1 for 3-oxo-1-butanol (simple alcohol having an acetyl group), bornyl acetate (monoacetate having a bulky and highly branched aliphatic moiety), 2,4-diacetoxypentane (simple diacetate), and cholestane (bulky hydrocarbon), respectively.
