Chrysene, radical anion

Of course, the same energetic requirements as in the direct production of excited singlet states ( S-route ) or the production of the latter via triplet states ( T-route ) are valid here as in ECL (see p. 130). As an example, the chemiluminescent reaction of Wurster s Blue radical cation (12) with chrysene radical anion (13) must occur via the T-route . The emission spectrum matches chrysene fluorescence, but the (12)/(13) redox reaction has an enthalpy corresponding to 2.66eV only, whereas the energy of the chrysene first excited singlet state is 3.43 eV. 

Preannihilative electrochemical oxidation of the phenanthrene anion has given a green emission13,64 spectrally nearly identical to the previously reported room-temperature phenanthrene phosphorescence which is a single broad peak.71 Chemical oxidation of the chrysene anion with Wurster s blue perchlorate produced an emission containing three bands at 19,800, 18,600, and 17,400 cm"1 which seem to correspond to the known phosphorescence bands of chrysene (19,500,18,500, and 16,600 cm-1). Chemical oxidation of the radical anion of N-methylcarbazole has possibly led to phosphorescent emission from this triarylamine.7... 

Bromobenzene cannot be reduced direetly at the potential used to generate the radical anion of chrysene. However, the radical anion can react chemically and rapidly with bromobenzene in solution ... 

Evans et (d. (1962) and Evans and Evans (1963) have studied electron-transfer from aromatic radical-anions to both tetraphenylethylene and 1,1,3,3-tetraphenylbut-l-ene. When the electron affinity of the hydrocarbon corresponding to the donor is large (e.g. anthracene), transfer is not observed when it is small (e.g. naphthalene), transfer is rapid and in two intermediate cases (picene and chrysene) donation is rapid to tetraphenylethylene and slow to 1,1,3,3-tetraphenylbut-l-ene. 

Reductive Remediation of Nonhalogenated Molecules. Na/NHa treatments can also destroy nonhalogenated hazardous conqraunds. Three classes pollutants will be mentioned here polynuclear aromatic hydrocarbons (PNAs), nitro- and nitrate-type explosive wastes and chemical warfare agents. The treatment of neat sanq>les of PNAs leads to destmction efficiencies of 99.99% for many of these conq)ounds including such examples as acenaphthene, benzo[a]anthracene, benzo[b]fluoranthene, benzo[g,h,l]perylene, chrysene, fluorandiene, fluorine, naphdialene and phenanthrene. With the exception of naphthalene and anthracene, conq)lex product mixtures are formed. Radical anion formation followed by protonation occurs sequentially leading to dihydro, tetrahydro and further reduced products (see Scheme 3). Depending on the reaction conditions, dimerization of intermediate radicals can occur to give dimers in various states of reduction. 

A large number of aromatic hydrocarbon radical anions has been reacted with Wurster s Blue-type radical cations, e.g. the radical anions of 1-phenylnaph-thalene, 8,8 -dimethyl-naphthalene, 1,1 -binaphthyl, p-terphenyl, chrysene, 1,2-dimethylchrysene [29]. They all represent energy-deficient systems, so that triplet-triplet annihilation had to be regarded as the mechanism for the production of the emitting singlet state. The quantum yields were in the range 10" to 10" Einstein/mol [29]. 

Lund and coworkers [131] pioneered the use of aromatic anion radicals as mediators in a study of the catalytic reduction of bromobenzene by the electrogenerated anion radical of chrysene. Other early investigations involved the catalytic reduction of 1-bromo- and 1-chlorobutane by the anion radicals of trans-stilhene and anthracene [132], of 1-chlorohexane and 6-chloro-l-hexene by the naphthalene anion radical [133], and of 1-chlorooctane by the phenanthrene anion radical [134]. Simonet and coworkers [135] pointed out that a catalytically formed alkyl radical can react with an aromatic anion radical to form an alkylated aromatic hydrocarbon. Additional, comparatively recent work has centered on electron transfer between aromatic anion radicals and l,2-dichloro-l,2-diphenylethane [136], on reductive coupling of tert-butyl bromide with azobenzene, quinoxaline, and anthracene [137], and on the reactions of aromatic anion radicals with substituted benzyl chlorides [138], with... 

Electroreductive one-electron initiation of cyclization was described for the series of E,E-, 1-dibenzoyl-l,6-heptadiene and its derivatives (Roh et al. 2002, Felton and Bauld 2004). In this case, the catalytic effect was also observed (the actual consumption of electricity was substantially less than theoretical). The same bis(enones) can also be cyclized on the action of the sodium salt of chrysene anion-radical in THF, but with no catalytic effect. Optimum yields were obtained only when 70-120 mol% of the initiator was used, relative to a substrate (Yang et al. 2004). The authors suggest that tight ion pairing of the sodium cation with the product anion-radical in THF (which is a somewhat nonpolar solvent) slows down the intermolecular electron transfer to the bis(enone) molecules. Such an electron transfer would be required for chain propagation. 

In some cases, such as chrysene and triphenylene, the transient absorption did not decay down to zero at all wavelengths. The spectra were then recorded before and after decay in order to verify that the observed decay is due to the dissappearance of the anion radical. The remaining absorption was sometimes assignable to the solvent radical (7 ). In most cases, however, the kinetic measurements were carried out at wavelengths above 450 nm where neither the solvent radical nor the product of protonation show any considerable absorption. 

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