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Titolo:
The electron as a protecting group. 2. Generation of benzocyclobutadiene radical anion in the gas phase and an experimental determination of the heatof formation of benzocyclobutadiene
Autore:
Broadus, KM; Kass, SR;
Indirizzi:
Univ Minnesota, Dept Chem, Minneapolis, MN 55455 USA Univ Minnesota Minneapolis MN USA 55455 t Chem, Minneapolis, MN 55455 USA
Titolo Testata:
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
fascicolo: 43, volume: 122, anno: 2000,
pagine: 10697 - 10703
SICI:
0002-7863(20001101)122:43<10697:TEAAPG>2.0.ZU;2-6
Fonte:
ISI
Lingua:
ENG
Soggetto:
HYDROGEN-DEUTERIUM EXCHANGE; MASS-SPECTROMETRY; VALENCE ISOMERISM; NEGATIVE-IONS; CYCLOBUTADIENE; RESONANCE; TETRAHEDRANE; SPECTROSCOPY; EXCITATION; ENERGY;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Physical, Chemical & Earth Sciences
Citazioni:
48
Recensione:
Indirizzi per estratti:
Indirizzo: Kass, SR Univ Minnesota, Dept Chem, 207 Pleasant St SE, Minneapolis, MN 55455 USA Univ Minnesota 207 Pleasant St SE Minneapolis MN USA 55455 55 USA
Citazione:
K.M. Broadus e S.R. Kass, "The electron as a protecting group. 2. Generation of benzocyclobutadiene radical anion in the gas phase and an experimental determination of the heatof formation of benzocyclobutadiene", J AM CHEM S, 122(43), 2000, pp. 10697-10703

Abstract

Benzocyclobutadiene radical anion (5) was synthesized in the gas phase by three independent approaches: collision-induced dissociation (CID) of 1,2-benzocyclobutenedicarboxylate, reaction of 2-trimethylsilyl-1 -benzocyclobutenyl anion with neopentyl nitrite followed by CID of the resulting beta -nitroso carbanion intermediate, and reaction of the same beta -silyl carbanion with molecular fluorine. The proton affinity and electron binding energy of 5 were measured (0.32 +/- 0.05 eV and 368 +/- 2 kcal mol(-1), respectively) and combined in a thermodynamic cycle to obtain the heat of hydrogenation (49 +/- 4 kcal mol(-1)) and the heat of formation (97 +/- 4 kcal mol(-1)) of benzocyclobutadiene (1), These results were compared to model compounds as well as MP2 and B3LYP calculations in order to assess the antiaromaticdestabilization energy of 1. Based upon our data, a predicted heat of formation for dyclobutadiene (102 kcal mol(-1)) was obtained. This work demonstrates the utility of dicarboxylates as radical anion precursors and the electron as a protecting group.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 28/11/20 alle ore 00:27:50