The Protonation of Aromatic π Carbocations. The Behavior of 2‐Hydroxy‐ and 9‐Hydroxyphenalenone in Trifluoromethanesulfonic Acid | Zendy

Pagni Richard M. | Zendy; Smith Robert J. | Zendy; Moore Theresa | Zendy; Burnett Michael N. | Zendy

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The Protonation of Aromatic π Carbocations. The Behavior of 2‐Hydroxy‐ and 9‐Hydroxyphenalenone in Trifluoromethanesulfonic Acid

Author(s) -

Pagni Richard M.,

Smith Robert J.,

Moore Theresa,

Burnett Michael N.

Publication year - 1980

Publication title -

israel journal of chemistry

Language(s) - English

Resource type - Journals

SCImago Journal Rank - 0.908

H-Index - 54

eISSN - 1869-5868

pISSN - 0021-2148

DOI - 10.1002/ijch.198000089

Subject(s) - carbocation , chemistry , protonation , medicinal chemistry , reactivity (psychology) , computational chemistry , organic chemistry , ion , alternative medicine , pathology , medicine

In continuation of work on the protonation of aromatic π carbocations, the behavior of 1,2‐dihydroxyphenalenyl cation ( 7 ) and 1,9‐dihydroxyphenalenyl cation ( 8 ) in CF 3 SO 3 D was investigated. The behavior of carbocation 8 was unexceptional. It underwent a facile exchange at room temperature, with H‐2, H‐5 and H‐8 all exchanging at comparable rates. Carbocation 7 , on the other hand, exchanged at an exceptionally slow rate, even at 100°C. The order of reactivity of the various sites on 7 was found to be H‐3 ≫ H‐5 ⪖ H‐4 ≈ H‐6; H‐7, H‐8 and H‐9 did not exchange. These unusual results are best accommodated by assuming that most, if not all, of the exchange actually occurs on 2‐hydroxyphenalenone ( 9 ) which is present in very low concentration. Hückel calculations support this contention.

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