Stabilities and structures in cluster ions of five-membered heterocyclic compounds containing O, N, and S atoms

Journal Article · Wed Nov 25 04:00:00 EST 1987 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00258a018· OSTI ID:5528040

Hiraoka, K; Takimoto, H; Yamabe, S

Clustering and hydration reactions of protonated and radical cations of heterocyclic compounds, e.g., furan, tetrahydrofuran, pyrrole, pyrrolidine, thiophene, and tetrahydrothiophene, have been studied using a pulsed electron beam mass spectrometer. The bond energies of proton-held dimer cations for furan, pyrrole, and thiophene are much smaller than those for tetrahydrofuran, pyrrolidine, and tetrahydrothiophene, respectively. This result suggests that not the heteroatoms but the ..cap alpha.. carbon atoms are protonated for furan, pyrrole, and thiophene. The hydrogen-bond site for the protonated furan and thiophene is calculated to be the unprotonated ..cap alpha.. hydrogen (C-H/sub ..cap alpha../ adjacent to the heteroatom) which is the most acidic one. On the other hand, the N-H hydrogen is the best hydrogen-bond site for the protonated pyrrole. It was found that the radical-cations dimers have greater bond energies than the proton-held dimer cations for furan and thiophene. This suggests that the bonds of the former have more covalent nature. Some unique reactions of C/sub 4/H/sub 4/O/sup .+/ and C/sub 4/H/sub 5/O/sup +/ with a furan molecule were observed. With an increase of temperature, the ions with m/z which are the same as those for (C/sub 4/H/sub 4/O)/sub 2//sup .+/ and H/sup +/(C/sub 4/H/sub 4/O)/sub 2/ are found to be formed at the expense of C/sup 4/H/sub 4/O/sup .+/ and C/sub 4/H/sub 5/O/sup +/ ions, respectively. It is suggested that the reactions observed are Diels-Alder type condensation reactions.

• Research Organization: Yamanashi Univ., Kofu, Japan
• OSTI ID: 5528040
• Journal Information: J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 109:24; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
500200 -- Environment
Atmospheric-- Chemicals Monitoring & Transport-- (-1989)
54 ENVIRONMENTAL SCIENCES
AZOLES
BEAMS
BINDING ENERGY
CATIONS
CHARGED PARTICLES
CHEMICAL REACTIONS
DATA
ELECTRON BEAMS
ENERGY
EXPERIMENTAL DATA
FURANS
HETEROCYCLIC COMPOUNDS
HYDRATION
INFORMATION
IONS
LEPTON BEAMS
MASS SPECTROSCOPY
MOLECULAR STRUCTURE
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
ORGANIC SULFUR COMPOUNDS
PARTICLE BEAMS
PULSE TECHNIQUES
PYRROLES
RADICALS
SOLVATION
SPECTROSCOPY
TETRAHYDROFURAN
THIOPHENE