940-10-3Relevant academic research and scientific papers
Aerobic oxidation of aldehydes to acids with N-hydroxyphthalimide derivatives
Takamatsu, Keigo,Kasai, Miku,Nishizawa, Hinaru,Suzuki, Rio,Konno, Hiroyuki
, (2021/09/14)
The N-hydroxyphthalimide derivative-mediated aerobic oxidation of a selection of aldehydes to the corresponding carboxylic acids in air is described. This reaction proceeds via rearrangement of the Creigee (carboxylic peracid) intermediate and/or by the treatment of H2O and/or sulfides. Optimization of reaction conditions established NHNPI (14) as a mild catalyst for the oxidation reaction in MeCN under an atmosphere of air.
Solvation Accounts for the Counterintuitive Nucleophilicity Ordering of Peroxide Anions
Mayer, Robert J.,Tokuyasu, Takahiro,Mayer, Peter,Gomar, Jér?me,Sabelle, Stéphane,Mennucci, Benedetta,Mayr, Herbert,Ofial, Armin R.
supporting information, p. 13279 - 13282 (2017/10/17)
The nucleophilic reactivities (N, sN) of peroxide anions (generated from aromatic and aliphatic peroxy acids or alkyl hydroperoxides) were investigated by following the kinetics of their reactions with a series of benzhydrylium ions (Ar2CH+) in alkaline aqueous solutions at 20 °C. The second-order rate constants revealed that deprotonated peroxy acids (RCO3?), although they are the considerably weaker Br?nsted bases, react much faster than anions of aliphatic hydroperoxides (ROO?). Substitution of the rate constants of their reactions with benzhydrylium ions into the linear free energy relationship lg k=sN(N+E) furnished nucleophilicity parameters (N, sN) of peroxide anions, which were successfully applied to predict the rates of Weitz–Scheffer epoxidations. DFT calculations with inclusion of solvent effects by means of the Integral Equation Formalism version of the Polarizable Continuum Model were performed to rationalize the observed reactivities.
One-pot epoxidation of alkenes using aerobic photoperoxidation of toluenes
Taguchi, Miyabi,Nagasawa, Yoshitomo,Yamaguchi, Eiji,Tada, Norihiro,Miura, Tsuyoshi,Itoh, Akichika
supporting information, p. 230 - 232 (2015/12/31)
We developed an aerobic photooxidative synthesis of peroxybenzoic acids from toluenes using anthraquinone-2-carboxylic acid (AQN-2-CO2H) as a photocatalyst. We also found a one-pot epoxidation reaction of alkenes using 4-tert-butylperoxybenzoic acid produced in situ by aerobic photooxidative synthesis.
Decatungstate catalyst supported on silica and γ-alumina: Efficient photocatalytic oxidation of benzyl alcohols
Tzirakis, Manolis D.,Lykakis, Ioannis N.,Panagiotou, George D.,Bourikas, Kyriakos,Lycourghiotis, Alexis,Kordulis, Christos,Orfanopoulos, Michael
, p. 178 - 189 (2008/09/18)
Four supported catalysts with the same tungsten loading were prepared by depositing decatungstate species W10O4-32, through wet impregnation, on the surface of γ-alumina and silica at different pH values. The prepared samples were characterized using BET measurements as well as XRD, UV-vis DR, and XP spectroscopies. Higher dispersion of W(VI) oxo-species was obtained in the silica-supported catalysts compared with the corresponding alumina-supported ones. Within the same support, the dispersion was higher when the impregnation pH is lower than the point of zero charge (pzc) of the support. The decatungstate anions were present mainly on the silica surface without any modification, whereas these underwent a partial depolymerization on their deposition on the γ-alumina surface. The extent of depolymerization was less in the sample prepared at pH above pzc. These findings were explained in terms of the mode of deposition of the W(VI) species from the solution onto the support surface. The photocatalytic activity of the aforementioned catalysts, concerning the photooxidation of 1-phenylethanol, depends on the fraction of the W10O4-32 supported species rather than on the W(VI) dispersion. Thus, extremely high conversions have been obtained over the silica-based catalysts and also over the γ-alumina-based catalyst prepared at relatively high pH. These catalysts also are very effective in the photooxidation of a series of secondary and primary benzyl alcohols, in which benzyl ketones and benzoic acids were formed as the only or major products, respectively. The easy separation of the solid catalyst from the reaction mixture, the high activity, selectivity, and stability as well as the retained activity in subsequent catalytic cycles, make these supported catalysts suitable for a small-scale synthesis. Based on product analysis and kinetic data on the heterogeneous oxidation of benzyl alcohols, we suggest that a hydrogen abstraction transfer (HAT) mechanism predominates with respect to an electron transfer (ET) one in these reactions.
The loss of carbon dioxide from activated perbenzoate anions in the gas phase: Unimolecular rearrangement via epoxidation of the benzene ring
Harman, David G.,Ramachandran, Aravind,Gracanin, Michelle,Blanksby, Stephen J.
, p. 7996 - 8005 (2007/10/03)
The unimolecular reactivities of a range of perbenzoate anions (X-C 6H5CO3-), including the perbenzoate anion itself (X = H), nitroperbenzoates (X = para-, meta-, orrtho-NO 2), and methoxyperbenzoates (X = para-, meta-OCH3) were investigated in the gas phase by electrospray ionization tandem mass spectrometry. The collision-induced dissociation mass spectra of these compounds reveal product ions consistent with a major loss of carbon dioxide requiring unimolecular rearrangement of the perbenzoate anion prior to fragmentation. Isotopic labeling of the perbenzoate anion supports rearrangement via an initial nucleophilic aromatic substitution at the ortho carbon of the benzene ring, while data from substituted perbenzoates indicate that nucleophilic attack at the ipso carbon can be induced in the presence of electron-withdrawing moieties at the ortho and para positions. Electronic structure calculations carried out at the B3LYP/6-311++G(d,p) level of theory reveal two competing reaction pathways for decarboxylation of perbenzoate anions via initial nucleophilic substitution at the ortho and ipso positions, respectively. Somewhat surprisingly, however, the computational data indicate that the reaction proceeds in both instances via epoxidation of the benzene ring with decarboxylation resulting-at least initially-in the formation of oxepin or benzene oxide anions rather than the energetically favored phenoxide anion. As such, this novel rearrangement of perbenzoate anions provides an intriguing new pathway for epoxidation of the usually inert benzene ring.
