619-19-2Relevant academic research and scientific papers
Palladium-catalyzed ortho-C-H hydroxylation of benzoic acids
Luo, Feihua,He, Shuhua,Gou, Quan,Chen, Jinyang,Zhang, mingzhong
, (2021/10/06)
A simple Pd(OAc)2 catalyzed ortho-hydroxylation of benzoic acids using TBHP as the sole oxidant has been explored. This protocol features relatively broad substrate scope and operational simplicity. The compatibility of ortho-substituted substrates is an effective complement to the previous ortho-hydroxylation reaction.
Catalytic oxidation of alcohols and alkyl benzenes to carbonyls using Fe3O4?SiO2?(TEMPO)-: Co -(Chlorophyll-CoIII) as a bi-functional, self-co-oxidant nanocatalyst
Hamah-Ameen, Baram Ahmed,Kazemnejadi, Milad,Mahmoudi, Boshra,Rostami, Amin
, p. 6600 - 6613 (2020/11/16)
Chlorophyll b was extracted from heliotropium europaeum plant, demetalated, allylated and grafted to acrylated TEMPO through a copolymerization protocol. Then, the chlorophyll monomers were coordinated to Co ions, immobilized on magnetic nanoparticles and the resulting hybrid was used as a powerful catalyst for a variety of oxidation reactions. By using the present method, oxidation of benzylic alcohols and alkyl benzenes to carbonyls was accomplished in water under aerobic conditions. Moreover, direct oxidation of alcohols to carboxylic acids was performed by adding NaOCl to the mixture. All entries were oxidized to the corresponding desired product with high to excellent yields and up to 97% selectivity. The catalyst was thoroughly characterized by CV, TGA, VSM, XRD, XPS, DLS, FE-SEM, TEM, UV-Vis, EDX, and BET analyses. The activity of the catalyst was investigated by applying various components of the catalyst to the oxidation model separately. The reasonable mechanisms are suggested based on the cooperation between the TEMPO groups and cobalt(iii) (or Co(iv)) sites on the catalyst. The catalyst could be recovered and reused for at least 7 consecutive recycles without any considerable reactivity loss. This journal is
Fe3O4@SiO2@Im[Cl]Mn(III)-complex as a highly efficient magnetically recoverable nanocatalyst for selective oxidation of alcohol to imine and oxime
Kazemnejadi, Milad,Alavi, Seyyedeh Ameneh,Rezazadeh, Zinat,Nasseri, Mohammad Ali,Allahresani, Ali,Esmaeilpour, Mohsen
, p. 230 - 249 (2019/03/28)
An efficient and environmentally friendly oxidation process for the one-pot preparation of oxime, imine and carbonyl compounds through alcohol oxidation in the presence of H2O2 and/or O2 have been developed by a melamine-Mn(III) Schiff base complex supported on Fe3O4@SiO2–Cl nanoparticles, named as Fe3O4@SiO2@Im[Cl]Mn(III)-complex nanocomposite, at room temperature. Direct oxidation of alcohol to carboxylic acid was performed using the catalyst in the presence of molecular O2 at room temperature in a different approach. The oxidation products were obtained with excellent yields and high TOFs. The properties of the catalyst were characterized by Fourier transform infrared spectroscopy (FTIR), elemental analysis (C, H, N), X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), dynamic light scattering (DLS), energy dispersive X-ray analysis (EDX), X-ray photoelectron spectroscopy (XPS), inductive coupled plasma (ICP), cyclic voltammetry (CV), nuclear magnetic resonance (1H & 13C NMR), vibration sample magnetometer (VSM), Brunauer– Emmett–Teller (BET) and differential pulse voltammetry (DPV) analyses. The mechanism of the oxidation processes was investigated for the both H2O2 and O2 oxidants. The role of the imidazolium moiety in the catalyst as a secondary functionality was investigated. Chemoselectivity behavior of the catalyst was studied by some combinations. The catalyst could be recycled from the reaction mixture by a simple external magnet and reused for several times without any considerable reactivity loss.
Sodium perborate/NaNO2/KHSO4-triggered synthesis and kinetics of nitration of aromatic compounds
Rajanna,Muppidi, Suresh,Pasnoori, Srinivas,Saiprakash
, p. 6023 - 6038 (2018/09/21)
Sodium perborate (SPB) was used as efficient green catalyst for NaNO2/KHSO4-mediated nitration of aromatic compounds in aqueous acetonitrile medium. Synthesis of nitroaromatic compounds was achieved under both conventional and solvent-free microwave conditions. Reaction times were comparatively shorter in the microwave-assisted than conventional reaction. The reaction kinetics for nitration of phenols in aqueous bisulfate and acetonitrile medium indicated first-order dependence on [Phenol], [NaNO2], and [SPB]. Reaction rates accelerated with introduction of electron-donating groups but retarded with electron-withdrawing groups. Kinetic results did not fit well quantitatively with Hammett’s equation. Observed deviations from linearity were addressed in terms of exalted Hammett’s constants (σˉ or σeff), para resonance interaction energy (ΔΔGp) parameter, and Yukawa–Tsuno parameter (r). This term provides a measure of the extent of resonance stabilization for a reactive structure that builds up charge (positive) in its transition state. The observed negative entropy of activation (?ΔS#) suggests greater solvation and/or cyclic transition state before yielding products.
Potassium Periodate/NaNO2/KHSO4-Mediated Nitration of Aromatic Compounds and Kinetic Study of Nitration of Phenols in Aqueous Acetonitrile
Sriram, Y. Hemanth,Fatima, Touheeth,Rajanna,Kumar, M. Satish,Raju, R. Madhusudan
supporting information, p. 622 - 632 (2017/06/30)
Synthesis and kinetics of potassium periodate(KIO4)/NaNO2/KHSO4)-initiated nitration of aromatic compounds have been studied in aqueous acetonitrile medium. Synthesis of nitroaromatic compounds is achieved under conventional and solvent-free microwave conditions. Reaction times in microwave-assisted reaction are comparatively less than in conventional reaction. The reaction kinetics for the nitration of phenols in aqueous bisulfate and acetonitrile medium indicated first-order dependence on [phenol], [NaNO2], and [KIO4]. An increase in [KHSO4] accelerated the rate of nitration under otherwise similar conditions. The rate of nitration increased in the solvent of high dielectric media (solvents with high dielectric constant (D)). Observed results were in accordance with Amis and Kirkwood plots [log k′ vs. (1/D) and [(D ? 1)/(2D + 1)]. These observations probably indicate the participation of anionic species and molecular or (dipolar) species in the rate-determining step. In addition, the plots of (log k′) versus volume% of organic solvent were also linear, which probably indicate the importance of both electrostatic and nonelectrostatic forces, solvent–solute interactions during nitration of phenols. Reaction rates accelerated with the introduction of electron-donating groups and retarded with electron-withdrawing groups, but results could not be quantitatively correlated with Hammett's equation and depicted deviations from linearity. These deviations could probably be attributed to cumulative effects arising inductive, resonance, and steric effects. Leffler's plot (ΔH# vs. ΔS#) was found linear indicating the compensation (cumulative) effect of both enthalpy and entropy parameters in controlling the mechanism of nitration.
Methyl salicylate as a selective methylation agent for the esterification of carboxylic acids
Chen, Si,Jia, Lei,Li, Xiaonan,Luo, Meiming
, p. 263 - 268 (2014/03/21)
Methyl salicylate is a selective and inexpensive methylating agent for the esterification of carboxylic acids with a wide range of functional group tolerance. The intramolecular hydrogen bonds between the carboxylate and hydroxyl groups in methyl salicylate are essential for the transformation. Allyl, benzyl, methallyl, and propargyl salicylates can also be used as alkylating agents for the preparation of the corresponding alkyl carboxylates.
PD(II)-CATALYZED HYDROXYLATION OF ARENES WITH O2 OR AIR
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Page/Page column 14; 19-20, (2011/04/24)
Pd (II) -catalyzed ortho-hydroxylat ion of variously substituted aromatic carboxylic acids under O2 or air is achieved under non-acidic conditions. Extensive labeling studies support a direct oxygenation of aryl C-H bonds with molecular oxygen.
Pd(II)-catalyzed hydroxylation of arenes with 1 atm of O2 or air
Zhang, Yang-Hui,Yu, Jin-Quan
supporting information; experimental part, p. 14654 - 14655 (2010/01/06)
(Chemical Equation Presented) Pd(II)-catalyzed ortho-hydroxylation of variously substituted benzoic acids under 1 atm of O2 or air is achieved under nonacidic conditions. Extensive labeling studies support a direct oxygenation of aryl C-H bonds with molecular oxygen.
Iron-promoted ortho-And/or ipso-hydroxylation of benzoic acids with H 2O2
Makhlynets, Olga V.,Das, Parthapratim,Taktak, Sonia,Flook, Margaret,Mas-Balleste, Ruben,Rybak-Akimova, Elena V.,Que Jr., Lawrence
experimental part, p. 13171 - 13180 (2010/07/03)
Regioselective hydroxylation of aromatic acids with hydrogen peroxide proceeds readily in the presence of iron(II) complexes with tetradentate aminopyridine ligands [FeII(BPMEN)-(CH3CN) 2](ClO4)2 (1) and [FeII(TPA)- (CH3CN)2](OTf)2 (2), where BPMEN=N, N'-dimethyl-N, N'-bis(2-pyridylmethyl)-1,2-ethylenediamine, TPA=tris-(2- pyridylmethyl)amine. Two cis-sites, which are occupied by labile acetonitrile molecules in 1 and 2, are available for coordination of H2O 2 and substituted benzoic acids. The hydroxylation of the aromatic ring occurs exclusively in the vicinity of the anchoring carboxylate functional group: ortho-hydroxylation affords salicylates, whereas ipso-hydroxylation with concomitant decarboxylation yields phenolates. The outcome of the substituent directed hydroxylation depends on the electronic properties and the position of substituents in the molecules of substrates:3-substituted benzoic acids are preferentially ortho-hydroxylated, whereas 2-and, to a lesser extent, 4-substituted substrates tend to undergo ipso-hydroxylation/decarboxylation. These two pathways are not mutually exclusive and likely proceed via a common intermediate. Electron-withdrawing substituents on the aromatic ring of the carboxylic acids disfavor hydroxylation, indicating an electrophilic nature for the active oxidant. Complexes 1 and 2 exhibit similar reactivity patterns, but 1 generates a more powerful oxidant than 2. Spectroscopic and labeling studies exclude acylperoxoiron(III) and FeIV=O species as potential reaction intermediates, but strongly indicate the involvement of an FeIII-OOH intermediate that undergoes intramolecular acid-promoted heterolytic O-O bond cleavage, producing a transient iron(V) oxidant.
Regio- and chemoselective enzymatic N-oxygenation in vivo, in vitro, and in flow
Winkler, Robert,Richter, Martin E. A.,Knuepfer, Uwe,Merten, Dirk,Hertweck, Christian
, p. 8016 - 8018 (2007/10/03)
(Chemical Equation Presented) Action by the para: Evaluation of the nitro-group-forming N-oxygenase AurF in vivo, in vitro, and immobilized as a fusion protein with simply H2O2 as oxidant (peroxide shunt) reveals para-regioselective oxygenation of aromatic amines (see scheme). This effect includes the selective oxygenation of diamino compounds.
