1005-01-2Relevant articles and documents
An infrared study on matrix-isolated benzoic acid
Reva, I. D.,Stepanian, S. G.
, p. 337 - 340 (1995)
The infrared spectra of benzoic acid and deuterobenzoic acid embedded in Ar matrices were obtained.The only benzoic acid conformer with syn position of O-H and C=O groups was found to fix in the matrices.We have demonstrated that both a raise of benzoic a
Correlation analysis of reactivity in the oxidation of substituted benzaldehydes by pyridinium hydrobromide perbromide
Aneja, Meenakshi,Kothari, Seema,Banerji, Kalyan K.
, p. 650 - 656 (2001)
The oxidation of benzaldehyde and 35 monosubstituted benzaldehydes by pyridinium hydrobromide perbromide (PHPB) in aqueous acetic acid leads to the formation of the corresponding benzoic acids. The reaction is first order with respect to each of the benzaldehydes and PHPB. Addition of pyridinium bromide has no effect on the rate of oxidation. The oxidation of [2H]benzaldehyde (PhCDO) indicated the presence of a substantial kinetic isotope effect. The effect of solvent composition indicated that the reaction rate increases with increase in the polarity of the solvent. The rates of oxidation of meta- and para-substituted benzaldehydes were correlated in terms of Charton's triparametric LDR equation whereas those of ortho-substituted benzaldehydes were correlated with a tetraparametric LDRS equation. The oxidations of para- and ortho-substituted benzaldehydes are more susceptible to the delocalization effect while the oxidation of meta-substituted compounds displays a greater dependence on the fi eld effect. The positive value of η suggests the presence of an electron-deficient reaction centre in the rate-determining step. The reaction is subjected to steric hindrance by the ortho substituents.
Combining Structural with Functional Model Properties in Iron Synthetic Analogue Complexes for the Active Site in Rabbit Lipoxygenase
Bonck, Thorsten,De Waal Malefijt, Matina Elo?se,Dobbelaar, Emiel,Kelm, Harald,Klein, Johannes E. M. N.,Krüger, Hans-J?rg,Rauber, Christian,Schmitz, Markus
, p. 13145 - 13155 (2021)
Iron complexes that model the structural and functional properties of the active iron site in rabbit lipoxygenase are described. The ligand sphere of the mononuclear pseudo-octahedral cis-(carboxylato)(hydroxo)iron(III) complex, which is completed by a tetraazamacrocyclic ligand, reproduces the first coordination shell of the active site in the enzyme. In addition, two corresponding iron(II) complexes are presented that differ in the coordination of a water molecule. In their structural and electronic properties, both the (hydroxo)iron(III) and the (aqua)iron(II) complex reflect well the only two essential states found in the enzymatic mechanism of peroxidation of polyunsaturated fatty acids. Furthermore, the ferric complex is shown to undergo hydrogen atom abstraction reactions with O-H and C-H bonds of suitable substrates, and the bond dissociation free energy of the coordinated water ligand of the ferrous complex is determined to be 72.4 kcal·mol-1. Theoretical investigations of the reactivity support a concerted proton-coupled electron transfer mechanism in close analogy to the initial step in the enzymatic mechanism. The propensity of the (hydroxo)iron(III) complex to undergo H atom abstraction reactions is the basis for its catalytic function in the aerobic peroxidation of 2,4,6-tri(tert-butyl)phenol and its role as a radical initiator in the reaction of dihydroanthracene with oxygen.
NMR studies of solid state - Solvent and H/D isotope effects on hydrogen bond geometries of 1:1 complexes of collidine with carboxylic acids
Tolstoy, Peter M.,Smirnov, Sergei N.,Shenderovich, Ilya G.,Golubev, Nikolai S.,Denisov, Gleb S.,Limbach, Hans-Heinrich
, p. 19 - 27 (2004)
1H and 15N NMR spectra of 10 complexes exhibiting strong OHN hydrogen bonds formed by 15N-labeled collidine and different proton donors, partially deuterated in mobile proton sites, have been observed by low-temperature NM
Extended tunnelling states in the benzoic acid crystal: Infrared and Raman spectra of the OH and OD stretching modes
Fillaux, Francois,Romain, Francois,Limage, Marie-Helene,Leygue, Nadine
, p. 4327 - 4336 (2006)
We compare Raman and infrared spectra of the νOH/OD modes in benzoic acid crystal powders at 7 K. The extremely sharp Raman bands contrast to the broad infrared profiles and suggest adiabatic separation of hydrogen (deuterium) dynamics from the crystal la
Theoretical modeling of infrared spectra of benzoic acid and its deuterated derivative
Boczar, Marek,Szczeponek, Krzysztof,Wójcik, Marek J.,Paluszkiewicz, Czes?awa
, p. 39 - 48 (2004)
Theoretical simulation of the νs stretching band is presented for benzoic acid and its OD derivative at 300 K. The simulation takes into account an adiabatic coupling between the high-frequency O-H(D) stretching and the low-frequency intermolec
The reaction of n-butyllithium with benzoic acid: Is nucleophilic addition competitive with deprotonation?
Beak, Peter,Pfeifer, Lance A.
, p. 537 - 541 (1997)
An evaluation of a branching vs sequential mechanism for the reaction of benzoic acid with n-butyllithium favors the latter.
Mechanism of the reaction of an NHC-coordinated palladium(II)-hydride with O2 in acetonitrile
Knapp, Spring M. M.,Konnick, Michael M.,Stahl, Shannon S.
, (2020)
PdII-hydride species are important intermediates in many Pd-catalyzed aerobic oxidation reactions, and their reaction with molecular oxygen has been the subject of considerable previous study. This investigation probes the reactivity of trans-[(IMes)2Pd(H)(OBz)] (IMes = 1,3-dimesitylimidazol-2-ylidene) with O2 in acetonitrile, a polar coordinating solvent that leads to substantial changes in the kinetic behavior of the reaction relative the previously reported reaction in benzene and other non-coordinating solvents. In acetonitrile, the benzoate ligand dissociates to form the solvent-coordinated complex trans-[(IMes)2Pd(H)(NCMe)][OBz]. Upon exposure to O2, this cationic PdII–H complex reacts to form the corresponding PdII-hydroperoxide complex trans-[(IMes)2Pd(OOH)(NCCD3)][OBz]. Kinetic studies of this reaction revealed a complex rate law, rate = k1k2[3][OBz]/(k?1[CD3CN] + k2[OBz]) + k3[3][OBz], which is rationalized by a mechanism involving two parallel pathways for rate-limiting deprotonation of the PdII–H species to generate the Pd0 complex, Pd(IMes)2. The latter complex undergoes rapid (kinetically invisible) reaction with O2 and BzOH to afford the PdII-hydroperoxide product. The results of this study are compared to observations from the previously reported reaction in benzene and discussed in the context of catalytic reactivity.
Polyethylene Terephthalate Deconstruction Catalyzed by a Carbon-Supported Single-Site Molybdenum-Dioxo Complex
Gao, Yanshan,Kratish, Yosi,Li, Jiaqi,Liu, Shanfu,Marks, Tobin J.
, p. 19857 - 19861 (2020)
Polyethylene terephthalate (PET) is selectively depolymerized by a carbon-supported single-site molybdenum-dioxo catalyst to terephthalic acid (PTA) and ethylene. The solventless reactions are most efficient under 1 atmosphere of H2. The catalyst exhibits high stability and can be recycled multiple times without loss of activity. Waste beverage bottle PET or a PET + polypropylene (PP) mixture (simulating the bottle + cap) proceeds at 260 °C with complete PET deconstruction and quantitative PTA isolation. Mechanistic studies with a model diester, 1,2-ethanediol dibenzoate, suggest the reaction proceeds by initial retro-hydroalkoxylation/β-C?O scission and subsequent hydrogenolysis of the vinyl benzoate intermediate.
Isotope Labeling Reveals Fast Atomic and Molecular Exchange in Mechanochemical Milling Reactions
Lukin, Stipe,Tireli, Martina,Stolar, Tomislav,Bari?i?, Dajana,Blanco, Maria Valeria,Di Michiel, Marco,U?arevi?, Krunoslav,Halasz, Ivan
, p. 1212 - 1216 (2019)
Using tandem in situ monitoring and isotope-labeled solids, we reveal that mechanochemical ball-milling overcomes inherently slow solid-state diffusion through continuous comminution and growth of milled particles. This process occurs with or without a ne
