9- fluorene oxidation

Bogan L, RT Lamar, KE Hammel (1996) Fluorene oxidation in vivo by Phanerochaete chrysosporium and in vitro during manganese peroxidase-dependent lipid peroxidation. Appl Environ Microbiol 62 1788-1792. 

Selective transformations Selective styrene ring opening [103] One-pot domino process for regioselective synthesis of a-carbonyl furans [104] Tandem process for synthesis of quinoxalines [105] Atmospheric oxidation of toluene [106] Cyclohexane oxidation [107] Synthesis of imines from alcohols [108] Synthesis of 2-aminodiphenylamine [109] 9H-Fluorene oxidation [110] Dehydrogenation of ethane in the presence of C02 [111] Decomposition of methane [112] Carbon monoxide oxidation [113]... 

Kumar, R., Garces, L.J., Son, Y., Suib, S.L. and Malz, R.E. (2005) Manganese oxide octahedral molecular sieve catalysts for synthesis of 2-aminodiphenylamine. Journal of Catalysis, 236, 387-391. Opembe, N.N., Son, Y., Sriskandakumar, T. and Suib, S.L. (2008) Kinetics and mechanism of 9H-fluorene oxidation catalyzed by manganese oxide octahedral molecular sieves. ChemSusChem, 1, 182-185. 

On the contrary, the oxidation of fluorene in a basic solution is not limited by the deprotonation of hydrocarbon [284]. This is in agreement with the oxidation of fluorene and 9,9-dideuterofluorene at the same rate in DMSO and 1,1-dimethylethanol solution. The stoichiometry of fluorene oxidation is close to unity (except oxidation in HMPA) and the main product of the reaction is fluorenone. The stoichiometry and the initial rate of the reaction depends on the solvent (conditions 300 K, [fluorene] = 0.1 mol L 1, [Me3COK] = 0.2mol L 1,p02 = 97kPa). 

Oxidation of diphenylmethane in basic solutions involves a process where rate is limited by and equal to the rate of ionization of diphenylmethane. The diphenylmethide ion is trapped by oxygen more readily than it is protonated in dimethyl sulfoxide-text-butyl alcohol (4 to 1) solutions. Fluorene oxidizes by a process involving rapid and reversible ionization in text-butyl alcohol solutions. However, in the presence of m-trifluoromethylnitrobenzene, which readily accepts one electron from the carbanion, the rate of oxygen absorption can approach the rate of ionization. 9-Fluorenol oxidizes in basic solution by a process that appears to involve dianion or carbanion formation. Benzhydrol under similar conditions oxidizes to benzophenone by a process not involving carbanion or dianion formation. 

The increase in the electron acceptor concentration in a solution transforms the reaction of fluorene oxidation into regime when the first stage (deprotonation of fluorene) limits the chain process. For the oxidation of other alkylaromatic hydrocarbons, see Refs. [292 304]. 

Figure 1. A reaction scheme for peroxidase catalysed amino-fluorene oxidation.

Fluorene can be nitrated, sulphonated and chlorinated. Oxidation gives fluorenone (9 O). 

Hydrogen chloride has also been eliminated from sulfinyl chlorides by addition of triethylamine. The thioketone oxide obtained from 9-fluorene-sullinyl chloride reacted with morpholinocyclohexene to give a zwitterionic adduct (475). 

One of the first examples was the above mentioned work from Yoshino et al. [7] concerning the synthesis of poly(9,9-dialkylfluorene)s via oxidative coupling of fluorene derivatives. Poly(9,9-dialkylfluorene) derivatives have been also synthesized via Ni- and Pd-catalyzed aryl-aryl homo- and cross-coupling reactions of sui-... 

Some alkyl substituents with a secondary benzylic carbon can be oxidized to ketones using KMn04 at 50 °C in water Eqqs. (35) and (36). In the case of the fluorene complex only, this oxidation could be alternatively achieved using aqueous... 

One of the first examples was that reported by Yoshino et al. [12] concerning the synthesis of polyfluorenes via oxidative coupling of fluorene derivatives as decribed above. 

Grifoll M, M Casellas, JM Bayona, AM Solanas (1992) Isolation and characterization of a fluorene-degrading bacterium identification of ring oxidation and ring fission products. Appl Environ Microbiol 58 2910-2917. 

Resnick SM, DT Gibson (1996) Regio- and stereospecific oxidation of fluorene, dibenzofuran, and dibenzothiophene by naphthalene dioxygenase from Pseudomonas sp. strain NCIB-4. Appl Environ Microbiol 62 4073-4080. 

As a proven technique for detecting reactive intermediates, flash pyrolysis seems to be the method of choice for direct detection or isolation of phosphenes. The result of thermal decomposition of (a-diazobenzyl)diphenylphosphine oxide (7) was nevertheless disappointing, since only triphenylmethane (75), fluorene (14), and benzophenone (75) but not the desired methyleneoxophosphorane 9 could be isolated 12). 

Hemoglobin is another heme-containing protein, which has been shown to be active towards PAH, oxidation in presence of peroxide [420], This protein was also modified via PEG and methyl esterification to obtain a more hydrophobic protein with altered activity and substrate specificity. The modified protein had four times the catalytic efficiency than that of the unmodified protein for pyrene oxidation. Several PAHs were also oxidized including acenaphthene, anthracene, azulene, benzo(a)pyrene, fluoranthene, fluorene, and phenanthrene however, no reaction was observed with chrysene and biphenyl. Modification of hemoglobin with p-nitrophenol and p-aminophenol has also been reported [425], The modification was reported to enhance the substrate affinity up to 30 times. Additionally, the solvent concentration at which the enzyme showed maximum activity was also higher. Both the effects were attributed to the increase in hydrophobicity of the active site. 

HTAB has been used, on the one hand, to increase the CL intensity of the reaction of 2,6,7-trihydroxy-9-(4 chlorophenyl)-3-fluorene with hydrogen peroxide in alkaline solution, in the presence of traces of Co(II) as a catalyst [43]. As a consequence, a CL method has been established for determination of ultratraces of Co(II). On the other hand, HTAB micelles sensitize the CL oxidation of pyro-gallol with A-bromosuccimide in an alkaline medium [44], while anionic and nonionic surfactants inhibit the CL intensity of this reaction (Table 3). This sensitized process allows the determination of pyrogallol by flow injection in an interval of 5 X 10 7-3 X 10 5 M. 

Parent (unsubstituted) PF was first synthesized electrochemically by anodic oxidation of fluorene in 1985 [266] and electrochemical polymerization of various 9-substituted fluorenes was studied in detail later [220,267]. Cyclic voltammogram of fluorene ( r1ed= 1.33 V, Eox = 1.75 V vs. Ag/Ag+ in acetonitrile [267]) with repetitive scanning between 0 and 1.35 V showed the growth of electroactive PF film on the electrode with an onset of the p-doping process at 0.5 V (vs. Ag/Ag+). The unsubstituted PF was an insoluble and infusible material and was only studied as a possible material for modification of electrochemical electrodes. For this reason, it is of little interest for electronic or optical applications, limiting the discussion below to the chemically prepared 9-substituted PFs. 

SCHEME 2.22 Oxidative coupling synthesis of poly(9,9-dihexyl)fluorene 195. (From Fukuda, M., Sawada, K., and Yoshino, K., Jpn. J. Appl. Phys., Pt. 2 — Letters, 28, L1433, 1989.)... 

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