Phenanthrenes electrochemical

Eused-ring polycycHc fluoroaromatics can be made from the corresponding amino fused-ring polycycHc or from preformed fluoroaromatics, eg, 4-fluorophenyl-acetonitrile [459-22-3] (275). Direct fluorination techniques have been successfully appHed to polycycHc ring systems such as naphthalene, anthracene, benzanthracenes, phenanthrene, pyrene, fluorene, and quinoHnes with a variety of fluorinating agents xenon fluorides (10), acetyl hypofluorite (276), cesium fluoroxysulfate (277), and electrochemical fluorination (278,279). 

The classical syntheses of phenanthrene and fluorenone fit well into the electron transfer scheme discussed in Section 8.6 and in this chapter. The aryl radical is formed by electron transfer from a Cu1 ion, iodide ion, pyridine, hypophosphorous acid, or by electrochemical transfer. The aryl radical attacks the neighboring phenyl ring, and the oxidized electron transfer reagent (e. g., Cu11) reduces the hexadienyl radical to the arenium ion, which is finally deprotonated by the solvent (Scheme 10-76). 

Pschorr s synthesis of phenanthrene (1893) in five steps with the essential dediazoniation and ring closure of 2-diazonio-a-phenylcinnamic acid giving, on addition of copper powder, phenanthrene-9-carboxylic acid, is today still the highest yielding one of all the reactions discussed in this section, Pschorr was able to get 93% yield, and today electrochemically induced Pschorr and related reactions141 give almost quantitative yields in several cases. 

The feasibility of a one-pot consecutive removal of the pyridinium moiety by reducing the products electrochemically in the same cell has been shown, thus providing a convenient synthetic route to 1-methylthio-acenaphthylene and 9-methylthio-phenanthrene (Eq. 19) [128]. 

Reduction of phenyldiazonium chloride in acetonitrile containing a high concentration of an aromatic substrate, which can act as a free-radical trap, leads to phenylation of the substrate in 14 - 33% yields together with 50 - 50% of benzene formed by phenyl radical attack on the acetonitrile [132], Intramolecular capture of the phenyl radical, in an electrochemical equivalent of the Pschorr reaction, is much more successful and phenanthrene derivatives can be prepared in 90 - 96% yield [133],... 

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... 

Electrochemical and ESR investigations with E- and Z-l,2-dihydro-l,2-diphenyl-cyclobuta[l]phenanthrene, E- and Z-126, indicate that the ring-opening reaction to give the rearranged dianion 130 may occur at the radical anion (727 -> 129) or the dianion 128 - 130) stage, depending on the ion pair conditions 88). 

Aryl pinacols are readily obtained from the photolysis of substituted benzophenones in isopropyl alcohol. Photochemical coupling of benzophenones in isopropyl alcohol has even been reported to occur in direct sunlight.7 It is known however, that some aryl ketones do not give the pinacol from photolysis in isopropyl alcohol.8 Nevertheless, aryl pinacols have also been prepared from electrochemical reduction,9 hydroxylation of olefins,10 photoreduction of ketones by amines,11 metal reduction,12 and by other routes.13 The phenanthrene ring system has often been... 

Alcantara T, Pazos M, Cameselle C, Sanromdn MA. (2008a). Electrochemical remediation of phenanthrene from contaminated kaolinite. Environmental Geochemistry and Health... 

AuE gold electrode DPV differential pulse voltammetry EIS electrochemical impedance spectroscopy GCE glassy carbon electrode (Ru(NH3)sL pentaamin ruthenium [3-(2-phenanthren-9-yl-vinyl)-pyridine] complex. 

Subsequent research showed the SrnI mechanism to occur with many other aromatic compounds. The reaction was found to be initiated by solvated electrons, by electrochemical reduction, and by photoinitiated electron transferNot only I, but also Br, Cl, F, SCeHs, N(CH3)3, and 0P0(0CH2CH3)2 have been foimd to serve as electrofuges. In addition to amide ion, phosphanions, thiolate ions, benzeneselenolate ion (C HsSe"), ketone and ester enolate ions, as well as the conjugate bases of some other carbon acids, have been identified as nucleophiles. The SrnI reaction was observed with naphthalene, phenanthrene, and other polynuclear aromatic systems, and the presence of alkyl, alkoxy, phenyl, carboxylate, and benzoyl groups on the aromatic ring does not interfere with the reaction. ... 

Electrochemical remediation of phenanthrene from contaminated kaolinite. Environ Geochem Health 30 89-94... 

Radical anions have been obtained electrochemically from condensed aromatic systems by electrolytic reduction of naphthalene [62, 117], 1,5-naphthalenedisulfonate [118], anthracene [54, 55, 62, 117-119], 9,10-diphenylanthracene [69, 120], phenanthrene [62, 117], tetracene [62, 118, 121], pyrene [62], pentacene [62], and perylene [62]. 

Radical anions have also been obtained from such condensed systems as azulene [122, 123], 4,6,8-trimethylazulene [122], acenaphthylene [124], and sym-dibenzocycloctatetraene [125]. Radical cations of phenanthrene [117] and of 9,10-diphenylanthracene [69] have been obtained by oxidative electrochemical generation at platinum electrodes. 

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