1530-12-7Relevant articles and documents
Stabilization of Carbanions by Polarization of Alkyl Groups on Nonadjacent Atoms
Bordwell, Frederick G.,Drucker, George E.,McCollum, Gregory J.
, p. 2504 - 2510 (1982)
Equilibrium acidities in dimethyl sulfoxide solution have been found to increase along the series Me, Et, i-Pr, t-Bu for 9-substituted fluorenes when the alkyl group, R, is separated from the fluorene ring by a CH2, S, or SO2 moiety.This is a reversal of
A Kinetic Study on Reduction of 9,9'-Bifluorenylidene by Sodium Isopropoxide
Kajigaeshi, Shoji,Fujisaki, Shizuo,Nakashige, Yasuhiko,Murakami, Sadaaki
, p. 833 - 837 (1982)
The kinetics and mechanism of reduction of 9,9'-bifluorenylidene (1) by sodium isopropoxide (2) in isopropyl alcohol to yield 9,9'-bifluorenyl (3) were investigated spectrophotometrically.The kinetic data suggest that the reduction proceeds autocatalytically, the reduction product 3 acting as the catalyst.It was found that (1) (2) Reactions 1 and 2 are of the first order with respect to 1, but that the former is of the third order with respect to 2, whereas the latter is of the first.The fourth- and third-order rate constants, k1 and k2 for Reactions 1 and 2 were determined to be 3.0 * 10-5 dm9 mol-3 s-1 and 1.1 * 103 dm6 mol-2 s-1, respectively, at 130 deg C.Probable mechanisms for Reactions 1 and 2 have been offered on the basis of the reaction order for each molecular species involved.
PHOTOCHEMICAL GENERATION OF RADICAL ANIONS. AN ACCESS TO NOVEL STRUCTURES
Huber, W.
, p. 181 - 184 (1985)
The preparation of the radical anions of tetrabenzocyclooctatetraene (TBCOT) and fluorene (FLH) by photochemical methods leads to the observation of novel structures.
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Suzuki,K.,Kajigaeshi,S.
, p. 408 - 412 (1962)
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Suzuki,Minabe
, p. 1541 (1974)
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Sprinzak
, p. 466,468 (1956)
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Bavin,P.M.G.
, p. 882 - 889 (1960)
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Tucker
, p. 2182,2185 (1949)
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Ion Pair Acidities of 9,9'-Bifluorenyl in THF: pK2 Is Lower than pK1
Stratakis, Manolis,Streitwieser, Andrew
, p. 1989 - 1990 (1993)
The second pK's in THF for lithium and cesium salts of 9,9'-bifluorenyl are 0.4 and 2.0 pK units, respectively, lower than the first pK's.
A facile synthesis of dithieno[3,2-b:6,7-b]fluorenes via a tandem annulation-reduction
Xiong, Xiaoli,Liu, Qiancai,Zhang, Jun,Zhu, Min,Wang, Yanmei,Deng, Shiming
, p. 17707 - 17711 (2013)
A concise and facile synthesis of 2,8-disubstituted dithieno[3,2-b:6,7-b] fluorenes starting from 2,7-dihydroxyfluorenone is reported. The key step involved is the tandem annulation-reduction of a 3,6-dichloro-2,7-di(alkynyl) fluorenone using Na2S·9H2O as a sulfur surrogate and reductant. The final dithiophene-fused fluorenes are obtained in reasonable yields (23-43%). The Royal Society of Chemistry.
Ogata,Y. et al.
, p. 1721 - 1722 (1976)
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Pinck,Hilbert
, p. 2739,2740 (1946)
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A Kinetic Study of the Photosolvolysis of 9-Fluorenol
Gaillard, Elizabeth,Fox, Marye Anne,Wan, Peter
, p. 2180 - 2186 (1989)
Excitation of 9-fluorenol in methanol and methanol-water mixtures leads to both heterolytic and homolytic cleavage via the singlet excited state.The partitioning between homolysis and heterolysis is controlled by solvent composition, the rate constant for cation formation being a function of the solvent dielectric constant.The rate constants of intersystem crossing, fluorescence, and singlet-derived radical formation are linear functions of the mole fraction of water.
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Pinck,Hilbert
, (1946)
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Evidence for the Generation of Aromatic Cationic Systems in the Excited State. Photochemical Solvolysis of Fluoren-9-ol
Wan, Peter,Krogh, Erik
, p. 1207 - 1208 (1985)
Photolysis of fluoren-9-ol (1) in aqueous methanol solution results in efficient formation of 9-methoxyfluorene (2); the driving force for the photosolvolysis is believed to be the formation of an aromatic 4? cationic system in the excited-state.
Erratum: Experimental Evidence for p Ka-Driven Asynchronicity in C-H Activation by a Terminal Co(III)-Oxo Complex (Journal of the American Chemical Society (2019) 141:9 (4051?4062) DOI: 10.1021/jacs.8b13490)
Anderson, John S.,Goetz, McKenna K.
supporting information, (2020/04/09)
It has been brought to our attention that our previous analysis of kinetic data for C-H activation was incomplete. For the reaction of PhB(tBuIm)3CoIIIO (3) with various substrates, the observed rate constants, kobs, were originally determined by plotting the natural log of the UV-vis absorbance at 470 nm at time t (At) divided by the initial absorbance (A0) versus time in seconds to give kobs as the slope of the linear fit of the data. However, this method implicitly assumes that the absorbance at infinite time, Ainf, is equal to 0. This is not true for these reactions due to absorbances from the reaction products, resulting in an underestimation of the true kobs values for each substrate. In order to obtain more accurate kobs values, the data were reanalyzed by fitting the absorbance versus time data at 470 nm to an exponential function, At = Ainf + (A0 - Ainf) e-kt. This method explicitly accounts for Ainf in the fitting parameters, providing more accurate values for the kobs for each substrate. For the Eyring analysis of the reaction between 3 and 9,10-dihydroanthracene, the noise and subsequent error in the measurements precluded good exponential fits of the variable-temperature data. Therefore, these data were analyzed by finding kobs as the slope of the linear fit of a plot of ln((At - Ainf)/(A0 - Ainf)) versus t in seconds, where Ainf was estimated from reactions carried out in a cuvette at room temperature. These new analyses result in the following corrections to the original Article.
Vanadium Pyridonate Catalysts: Isolation of Intermediates in the Reductive Coupling of Alcohols
Griffin, Samuel E.,Schafer, Laurel L.
supporting information, (2020/04/15)
The reductive coupling of alcohols using vanadium pyridonate catalysts is reported. This attractive approach for C(sp3)-C(sp3) bond formation uses an oxophilic, earth-abundant metal for a catalytic deoxygenation reaction. Several pyridonate complexes of vanadium were synthesized, giving insight into the coordination chemistry of this understudied class of compounds. Isolated intermediates provide experimental mechanistic evidence that complements reported computational mechanistic proposals for the reductive coupling of alcohols. In contrast to previous mononuclear vanadium(V)/vanadium(III)/vanadium(IV) cycles, this pyridonate catalyst system is proposed to proceed by a vanadium(III)/vanadium(IV) cycle involving bimetallic intermediates.
Experimental Evidence for p Ka-Driven Asynchronicity in C-H Activation by a Terminal Co(III)-Oxo Complex
Goetz, McKenna K.,Anderson, John S.
supporting information, p. 4051 - 4062 (2019/03/07)
C-H activation by transition metal oxo complexes is a fundamental reaction in oxidative chemistry carried out by both biological and synthetic systems. This centrality has motivated efforts to understand the patterns and mechanisms of such reactivity. We have therefore thoroughly examined the C-H activation reactivity of the recently synthesized and characterized late transition metal oxo complex PhB (tBuIm)3CoIIIO. Precise values for the pKa and BDFEO-H of the conjugates of this complex have been experimentally determined and provide insight into the observed reactivity. The activation parameters for the reaction between this complex and 9,10-dihydroanthracene have also been measured and compared to previous literature examples. Evaluation of the rates of reaction of PhB(tBuIm)3CoIIIO with a variety of hydrogen atom donors demonstrates that the reactivity of this complex is dependent on the pKa of the substrate of interest rather than the BDEC-H. This observation runs counter to the commonly cited reactivity paradigm for many other transition metal oxo complexes. Experimental and computational analysis of C-H activation reactions by PhB(tBuIm)3CoIIIO reveals that the transition state for these processes contains significant proton transfer character. Nevertheless, additional experiments strongly suggest that the reaction does not occur via a stepwise process, leading to the conclusion that C-H activation by this CoIII-oxo complex proceeds by a pKa-driven "asynchronous" concerted mechanism. This result supports a new pattern of reactivity that may be applicable to other systems and could result in alternative selectivity for C-H activation reactions mediated by transition metal oxo complexes.
