52399-80-1Relevant articles and documents
Solution structure of some λ3 iodanes: An 17O NMR and DFT study
Mocci, Francesca,Uccheddu, Gianluca,Frangia, Angelo,Cerioni, Giovanni
, p. 4163 - 4168 (2008/02/05)
(Figure Presented) The structure of a series of I-O bonded bis(acyloxy)iodoarenes and benzoiodoxolones in chloroform solution has been investigated by 17O NMR spectroscopy and by density functional theory (DFT) calculations, employing the PBE0 functional together with the LANL2DZ basis set extended with polarization (d) and diffuse (p) functions. This combined approach allowed us to ascertain that, although these classes of λ3 iodanes maintain in chloroform solution their solid state "T-shaped" structure, a degenerate [1,3] sigmatropic shift of iodine between the two oxygens of the acyloxy groups occurs in solution. The energy barrier involved in this process differs in the two classes, thus causing significant differences in the 17O NMR spectra, at room temperature, of the two classes of compounds.
Kinetics and mechanisms of the reactions of benzoyl derivatives of nucleophiles: Dependence of the solvation requirement of the reaction on the structures of the nucleophile and the acyl group
El Seoud, Omar A.,Ferreira, Monica,Rodrigues, Wagner A.,Ruasse, Marie-Francoise
, p. 173 - 182 (2007/10/03)
The reactions of two series of benzoyl derivatives of nucleophiles were investigated and the results were compared with those for N-benzoylimidazole. The general structure is ArCO-Nu, where Ar = X-C6H4 and/ or X2C6H3; X = 4-Me, H, 4-C1, 4-CN, 4-NO 2 and X2 = 3,5-dinitro; Nu = iodosobenzoate, ArCO-Iba, and phosphate dianion, ArCO-Phos. Catalytic rate constants, kinetic solvent isotope effects, kinetic substituent effects (Hammett equation) and the dependence of HΔ≠ and ΔS≠ on σx were determined. For ArCO-Iba, the hydrolysis occurs via two pathways, uncatalyzed (κ H2O) and specific base-catalyzed (κ OH) water attack on the iodine atom of the iodosobenzoate ring. This conclusion is based on theoretical calculations of the partial charges on ArCO-Iba, and the small ρ values calculated at 25°C, -0.22 and 0.92 for κ H2O and koH, respectively. The data for the reaction of ArCO-Phos are consistent with a dissociative transition state, leading to elimination of the metaphosphate monoanion (PO3 ). The dependence of the mechanistic pathway on the nucleophile is discussed. Two results are relevant to the reactions of ArCO-Iba: (i) moderate to large substituent effects on the activation entropies suggest that solvation of the leaving benzoate anion and desolvation of the entering nucleophile contribute to the OH -mediated reaction; (ii) the negative and positive signs of ΔS≠ indicate large differences in solvation of the transition states of the κH2O and κOH pathways. For the spontaneous decomposition of ArCO-Phos, sizeable substituent effects on both ΔH≠ and ΔS≠ were observed. This shows the contribution of solvation of the leaving benzoate and substituent-induced shift of the structure of the transition state. Copyright
