The gas-phase basicity (GB) of four benzocycloalkenes (benzocyclobutene, indan, tetralin and benzocycloheptene) has been determined by Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry, allowing proton transfer equilibria to be established with reference bases of known GB. The values obtained are all very similar, 776.8-778.8 kJ mol(-1) at 300 K, practically equal within experimental error and close to the GB of o-xylene. In this respect, any specific behavior which might be ascribed to the size of the fused ring is not manifested. H/D exchange reactions with CH3OD have been used to probe the structure of the protonated benzocycloalkenes. The positive-ion chemistry of protonated benzocyclobutene is characterized by its kinetic instability towards rearrangement into a more stable isomer(s). The isomerization is prompted either by an exothermic protonation process, for example using i-C3H7+ as proton donor, or within an ion neutral complex with a polar molecule.

Gas-phase protonation of benzocycloalkenes / Chiavarino, Barbara; Crestoni, Maria Elisa; Fornarini, Simonetta. - In: EUROPEAN JOURNAL OF MASS SPECTROMETRY. - ISSN 1469-0667. - STAMPA. - 10:6(2004), pp. 881-887. [10.1255/ejms.705]

Gas-phase protonation of benzocycloalkenes

CHIAVARINO, Barbara;CRESTONI, Maria Elisa;FORNARINI, Simonetta
2004

Abstract

The gas-phase basicity (GB) of four benzocycloalkenes (benzocyclobutene, indan, tetralin and benzocycloheptene) has been determined by Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry, allowing proton transfer equilibria to be established with reference bases of known GB. The values obtained are all very similar, 776.8-778.8 kJ mol(-1) at 300 K, practically equal within experimental error and close to the GB of o-xylene. In this respect, any specific behavior which might be ascribed to the size of the fused ring is not manifested. H/D exchange reactions with CH3OD have been used to probe the structure of the protonated benzocycloalkenes. The positive-ion chemistry of protonated benzocyclobutene is characterized by its kinetic instability towards rearrangement into a more stable isomer(s). The isomerization is prompted either by an exothermic protonation process, for example using i-C3H7+ as proton donor, or within an ion neutral complex with a polar molecule.
2004
benzocycloalkenes; benzocycloatkenes; ff-icr mass spectrometry; ft-icr mass spectrometry; gas phase basicity; gas-phase basicities; h/d exchange reactions; ion neutral complex; proton transfer reactions; site-selective protonation; structure elucidation
01 Pubblicazione su rivista::01a Articolo in rivista
Gas-phase protonation of benzocycloalkenes / Chiavarino, Barbara; Crestoni, Maria Elisa; Fornarini, Simonetta. - In: EUROPEAN JOURNAL OF MASS SPECTROMETRY. - ISSN 1469-0667. - STAMPA. - 10:6(2004), pp. 881-887. [10.1255/ejms.705]
File allegati a questo prodotto
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/233784
 Attenzione

Attenzione! I dati visualizzati non sono stati sottoposti a validazione da parte dell'ateneo

Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 3
  • ???jsp.display-item.citation.isi??? 3
social impact