Stable carbonium ions. IC. Benzenonium ion (C6H7+) and its degenerate rearrangement

Formation of dications bearing a S(OH)2+ group from long-lived 9,9-dimethyl-10 R-phenanthrenium cations in FSO3H–SbF5/SO2ClF/SO2: a mechanistic study

“…The protons corresponding to this signal are involved in slow exchange with acid protons and the NOE crossrelaxation is observed between these protons and H 6 and H 8 signals. By analogy to the literary data [1][2][3]7 according to which the protons of S(OH) 2 + group in cations Ar-S(OH) 2 + do not exhibit fast exchange with acidic media and show distinct signals with chemical shis in the range d 9.12-9.63 ppm we believe that the new signal in our case belongs to S(OH) 2 + group and the new formed particle is 7-dihydroxysulfonio-9,9-dimethyl-10-phenylethynylphenanthrenium dication 3a (Scheme 1). Additional evidences for its dicationic nature are downeld shis of all signals in the 1 H NMR spectrum (Fig.…”

“…in 0.12 mL of CD 2 Cl 2 was added dropwise to solution of FSO 3 H (130 mg, 1.3 mmol) and SbF 5 (250 mg, 1.2 mmol) in 0.3 mL of SO 2 ClF-SO 2 (8% SO 2 ) placed into NMR tube under stirring at À95 C. Formation of cation 1a 5 was observed. The tube was kept for 10 min at À71 C and then cooled down to À81 C. 1 Analogous NMR spectra were obtained for solution in SO 2 at À61 C (ESI, p. S7 †). The signal of S(OH) 2 + group is observed at d 9.86 ppm.…”

“…[1][2][3] The mechanism of this reaction may consist of addition of SO 2 to arenium cations formed under protonation of aromatics or electrophilic attack of the cation SO 2 H + or complex of SO 2 with SbF 5 on the aromatics involved in equilibrium with arenium ions. 1,4 These mechanisms suggest the opposite effect of the substituent R on the reaction rate. While studying the long-lived 9,9-dimethyl-10-R-phenanthrenium cations 5, 6 we have found that these cations are convenient model structures for study of carbocation reactions mechanisms.…”

Superacid‐Catalyzed Reactions

“…(5.168)]. Olah et al 466 observed immediate formation of protonated benzenesulfinic acid upon addition of SO 2 to benzenium ion formed in HSO 3 F-SbF 5 -SO 2 ClF solution at À78 C. Based upon this observation, Laali and Nagvekar 467 developed a method for the synthesis of aromatic sulfoxides [Eq. Olah et al 466 observed immediate formation of protonated benzenesulfinic acid upon addition of SO 2 to benzenium ion formed in HSO 3 F-SbF 5 -SO 2 ClF solution at À78 C. Based upon this observation, Laali and Nagvekar 467 developed a method for the synthesis of aromatic sulfoxides [Eq.…”

Infrared detection of the 1,3-dimethyl cyclopentadienyl cation, an isomer of protonated toluene

“…C 7 H 7 + ions are known to adopt the benzylium and tropylium ion structures, although limited spectroscopy is available for this system [15][16][17][18][19]. Protonated benzene was shown by Olah and coworkers to have only the -protonated form [20,21], and recent gas phase IR measurements confirmed this, revealing the full vibrational spectrum [22][23][24][25]. However, protonated toluene (C 7 H 9 + ) may be associated with several isomeric structures [25,26].…”