Fluorenone

About: Fluorenone is a research topic. Over the lifetime, 1067 publications have been published within this topic receiving 17162 citations. The topic is also known as: Diphenylene ketone & 9-Oxofluorene.

The Similarity between the π,π* Absorption Spectra of 1-Indenone and 1,2-Naphthoquinone

Abstract: The π,π* absorption spectrum and its solvent effect of 2-methyl-1-indenone have been found to be similar to those of 1,2-naphthoquinone. This fact is discussed on the basis of the results calculated using the P-P-P method. The similarity of the calculated π-electronic structures in the low-energy π,π* singlet states between 1-indenone and 1,2-naphthoquinone is not so good as that between fluorenone and 9,10-phenanthrenequinone.

Stoichiometry and mechanism of protonation of alkali metal salts of benzophenone radical anions by weak proton donors and its relevance to the base-catalyzed decomposition of benzopinacol

Abstract: The Stoichiometry of the protonation of lithium and potassium salts of benzophenone radical anions and of the lithium salt of the fluorenone radical anion by methanol has been measured and found to be [(Ar2C=O)−]/[MeOH] =2∶1. This result, which was obtained by the method of magnetic titration, implies that paramagnetism decays by the reaction between a ketyl anion and a ketyl radical (i.e., a protonated ketyl anion). The reactivities of alkali metal salts of fluorenone radical anions in relation to methanol exhibit a pronounced dependence on the nature of the counterion. No kinetic deuterium isotope effect has been found for the protonation of the lithium salt of the benzophenone radical anion in tetrahydrofuran (THF) bytert-pentyl alcohol. The lithium salt of the benzophenone radical anion inN,N,N′,N′-tetramethylethylenediamine (TMEDA) behaves markedly differently. Namely, its protonation by methanol exhibits 1 ∶ 1 Stoichiometry and it reacts considerably more slowly withsec-butyl alkohol,K(THF)/K(TMEDA) = 2.5. Benzopinacol undergoes decomposition by an alkoxide base to diphenyl ketyl, which decays into an equimolar mixture of benzophenone and benzhydrol. The reaction follows second-order kinetics and the specific rate constants exhibit an inverse relationship with respect to the initial concentration of the alkoxide. With a very strong base benzopinacol decomposes into two diphenyl ketyl anions. On the basis of this information as well as on studies of products, relevant mechanisms are proposed for the protonation of ketyl anions and for the decomposition of aromatic pinacols in basic media.

The red-edge effect in the spectra of fluorenone and 4-hydroxyfluorenone alcohol solutions

Abstract: Photophysical parameters of fluorenone and 4-hydroxyfluorenone have been studied in various solvents using steady state and time-resolved spectroscopic measurements. The fluorescence spectrum of both molecules in hydrogenbonding solvents is inhomogeneously broadened and strongly red shifted in comparison to that determined in nonploar and polar media. At 77 K the fluorescence spectra of the protic solvents are blue shifted (posses a changed intensity distribution) whereas in polar and nonploar one they are red shifted. In H-bond solvents at 77 K the fluorescence spectra of both molecules show an excitation wavelength dependence - the red-edge effect. The observed changes of the spectra are confirmed by the results of fluorescence decay measurements. The obtained results are explained by taking into consideration the statistical distribution of the solute-solvent interaction energies and the correlations between the fluorescence rate k F , solvent-cage relaxation rate τ - 1 R and the vibronic relaxation rate τ - 1 V .