The Use of Aluminum Chloride-Nitromethane for the Production of Cation Radicals¹

Organic and biological spectrochemical studies. XXIV. Electron spin resonance studies on the hydroquinone cation radical

“…T o calculate possible values for Q, , , a value for the spin density on the ring was first obtained by use of eq. [5] with the experimentally determined splitting constant (-2.25G) and QCB = -24, thus giving pc = 0.0937. Molecular orbital calculations based on the McLachlan molecular orbital-self-consistent field theory (13) with X = 1.2 were then carried out.…”

“…The radical was produced by reaction with aluminium chloride -nitromethane (3)(4)(5). The spectra were determined as described previously (1).…”

Radical ions as reactive intermediates in oxidation, substitution and electron transfer reactions

“…Ar +e>Ar: ROH>ArH-+e>ArH 2-ROH~ArH2 (60) Recent investigations by Szwarc la, however, indicate that protonation of the radical anions of polycyclic hydrocarbon (e.g. perylene radical anion, P'-) proceeds through the dianion, eq.…”

“…In some cases, however, the comproportionation reaction (11) has been shown independently, not to take place, and so the observation of the radical anions of naphthalene and tetraphenylethylene in the aerial oxidation of 1,4-dihydronaphthalene and 1,1,2,2-tetraphenylethane is unequivocable evidence of the pathway (6)- (9) or the alternative sequence (6') - (8'). The oxidation of hydroazobenzene in DMSO -t7rH 2 + B" Z 7rH" + HB (6') 7rH" + O7 -, rrH-+ 02: (7') 7rH-+ B" -, 7r: + HB (8') butanol (50:50) in the presence of potassium t-butoxide was found to require 2 moles of oxygen and gave almost 2 moles of potassium superoxide (KO2) as required by steps (6), (7) and (8) 49 The production of superoxides from the reaction of radical ions and oxygen has been quantitatively investigated for the radical anions of nitrobenzene s° , and azobenzene 49 , and hence production of superoxide indicates the radical anion oxidation process is occurring, although the absence thereof is not proof that the radical anion is not an intermediate (CH3)2C=N02" + ~02 -~ (CH3)2C=0 + NO 2 (12) This reaction was shown to be a chain reaction, the initiation step of which is shown in eq.…”

Organic Radical Ions as Studied by Epr Spectroscopy

“…This rather crude procedure has been superseded by more refined ones, in which the oxidation is carried out in nitromethane, dichloromethane, or l,l,l,3,3,3-hexafluoropropano-2ol with a variety of reagents including trifluoroacetic acid (51), SbCl s (52), and A1C1 3 (53), as well as salts of Ag + (54), Hg 2+ (55), Tl 3+ (56,141), Pb 4+ (57), Co 3+ (58), and tris(p-bromophenyl)ammomumyl cation (59,60) . In particular, A1C1 3 in dichloromethane proved to be the system of choice for hydrocarbons (61), thiaheterocycles (62), and organosilicon compounds (63), while tris(pbromophenyl)ammoniumyl hexa-chloroantimonate in this solvent was more appropriate for some nitrogen-containing compounds (64).…”