59431-17-3Relevant academic research and scientific papers
Equilibrium Acidities of Nitroalkanes in an Ionic Liquid
Gao, Feixiang,Ji, Pengju,Cheng, Jin-Pei
, p. 14962 - 14968 (2019/01/03)
The acidity ladder scale in [BMPY][NTf2] was successfully expanded toward the weak acidity region for about five more pK units compared to the previously established one. This allows the acidities of a series of 13 aliphatic and aromatic nitroalkanes to be determined accurately by the UV-vis spectroscopic method. The acidity of nitroalkane in [BMPY][NTf2] covers ～8 pK units and is significantly weaker than those in DMSO and water. The Hammett plot for 4-substituted phenylnitromethanes shows an excellent linearity with a slope of 2.06, which is rather close to that in DMSO but significantly larger than that in water (0.80). The regression analyses reveal that the solvation behavior of [BMPY][NTf2] on the acidic dissociations of C-H acids is similar to that of DMSO.
Synthesis and conformational study of 1,1'-ethano-9,9'-bifluorenyl. Anti and Gauche conformers of a 9,9'-bifluorenyl derivative and chair and twist conformers of a dibenzo-1,5-cyclooctadiene derivative
Lai,Lee,Lee,Yi
, p. 2437 - 2446 (2007/10/02)
A Hofmann-type elimination of the sulphonium salt (18) under basic conditions led to the formation of a novel o-xylylene derivative (11) which dimerized regioselectively to give the bifluorenyl/dibenzo-1,5-cyclooctadiene derivative (3). The reaction is shown to be kinetically controlled and non-concerted. The two rigid conformers (3a) and (3b) were characterised by their 1H NMR spectra and they represent respectively the first observed examples of an anti bifluorenyl derivative and a twist dibenzo-1,5-cyclooctadiene derivative. A semiempirical molecular orbital PM3 calculation supported the observed results. Dynamic 1H NMR studies indicated an interconversion process (3a) ? (3b) at higher temperatures involving a conformational barrier estimated at 65.2 kJ mol-1.
Rates of H/D Exchange of 9-Fluorenyl Sulfoxides: Evidence for an Irreversible E1cB Mechanism for Base-Induced Sulfine Formation from Methyl Diarylmethanesulfinates
Kice, John L.,Lotey, Harvinder
, p. 3593 - 3597 (2007/10/02)
A previous study had shown that the base-catalyzed, sulfine-forming eliminations of methyl 9-fluorenesulfinate (4) and other methyl diarylmethanesulfinates take place by either an E1cB-irreversible or an E2 mechanism, rather than the E1cB-reversible mechanism that had been expected.In the present work the rates (kexch) of DABCO (diazacyclooctane)-catalyzed H/D exchange of the 9-H in a series of 9-fluorenyl sulfoxides (3) have been determined at 25 deg C in CD3OD.From a plot of log kexch vs ?* for R in 3 the anticipated rate for the DABCO-catalyzed formation ofthe 9-fluorenyl carbanion from 4 (eq 3, R = OCH3) can be estimated.Comparison of this rate with the actual rate (kelim) of the DABCO-catalyzed, sulfine-forming elimination of 4 (eq 5) indicates that the elimination does not take place by an E2 mechanism in which there is a significant degree of cleavage of the S(O)-OCH3 bond in the rate-determining transition state.The results are, however, entirely consistent with an E1cB-irreversible mechanism for the elimination.
Photo-Stevens Rearrangement of 9-Dimethylsulfonium Fluorenylide
Zhang, Jian-Jian,Schuster, Gary B.
, p. 716 - 719 (2007/10/02)
The direct irradiation of 9-dimethylsulfonium fluorenylide (DMSF) in acetonitrile or THF gives primarily the Stevens rearrangement product 9-methyl-9-(methylthio)fluorene and the dimeric bis.The mechanism of this reaction was investigated by kinetic, product, and isotope tracer techniques.The results indicate that the primary photochemical step is bond homolysis from an n?* singlet state of the ylide.Oxidation of the ylide does not lead to chemical reaction.
Reactions of Triplet Carbenes with Sulfides and Disulfides: Ylide vs. Radical Formation
Alberti, A.,Griller, D.,Nazran, A. S.,Pedulli, G. F.
, p. 3024 - 3028 (2007/10/02)
The reactions between triplet diphenylcarbene and fluorenylidene with a variety of sulfides and disulfides were investigated with use of electron paramagnetic resonance (EPR) spectroscopy, laser flash photolysis, and product studies.Diphenylcarbene reacted with these substrates by a radical-like displacement mechanism.Rate constants were ca. 1E6 M-1 s-1, and the resulting thio-substituted diphenylmethyl radicals were identified by their EPR and optical spectra.By contrast, the analogous reactions of fluorenylidene had rate constants of 1E8-1E9 M-1 s-1 and proceeded by an ylide mechanism.Product studies were consistent with these results but were not sufficient in themselves to reveal these mechanistic differences.
