16554-54-4Relevant articles and documents
Further Evidence for the Triplet Mechanism in the Photosubstitution of Nitroaryl Ethers in Alkaline Medium.
Bonilha, Joao Baptista Sargi,Tedesco, Antonio Claudio,Nogueira, Lazaro Cicero,Ribeiro, Maria Teresa,Diamantino, Silva,Carreiro, Julio Cesar
, p. 3053 - 3064 (1993)
Mechanistic studies show that nitroaryl ethers (3-nitroanisole, 3-nitrophenetole, n-butyl 3-nitrophenyl ether, 2-chloro-5-nitroanisole, 2-bromo-5-nitroanisole and 3,5-dinitroanisole) undergo nucleophilic aromatic photosubstitution with hydroxide ions through an SN23Ar* mechanism.An investigation of the quenching of excited states of nitroaryl ethers by bromide and thiosulfate ions in aqueous solutions is reported and lends support to the proposed SN23Ar* mechanism.Key Words: Photosubstitution; Nitroaryl Ethers; Triplet Lifetime; Quencher.
Kinetic studies of the nucleophilic quenching of photoexcited nitroaryl ethers (NArE) by bromide ions in cationic micellar solution
Tedesco, Antonio C.,Naal, Rose M. Z. G.,Carreiro, Julio C.,Bonilha, Joao B. S.
, p. 3071 - 3080 (1994)
Nucleophilic aromatic photosubstitution reactions of nitroaryl ethers (NArE) with sodium hydroxide were studied in aqueous solution containing N- hexadecyl-N,N,N-trimethylammonium chloride micelles. The increase of quantum yields depended on the length of the n-alkyl chain (maximum for methyl and minimum for decyl). The dependence on the surfactant concentration was in accordance with the mechanistic model of aromatic nucleophilic photosubstitution.
Reactivity of the 3-Nitroanisole Triplet: Methanol Inhibition of Photohydroxylation
Evans, Christopher H.,Arnadottir, Gudrun,Scaiano
, p. 8777 - 8783 (1997)
The reactivity of the triplet state of 3-nitroanisole (1) toward a series of quenchers has been investigated in water and water alcohol mixtures. The triplet is a relatively efficient hydrogen abstractor, a very efficient electron acceptor, but a poor electron donor. Hydroxide quenches the triplet state via nucleophillic aromatic substitution. Methanol inhibition of the SN2 Ar* reaction of hydroxide with triplet 1 in water at pH 12 was examined by steady-state and time-resolved methods HPLC measurements show that a product in addition to 3-nitrophenolate is formed in trace amounts (≤1% of total material) when methanol is present. 2-Propanol, tert-butyl alcohol and trifluoroethanol do not quench the reaction nor does their presence lead to formation of additional products. Methanol quenching of the reaction follows Stern-Volmer behavior with Ksv = 0 36 ± 0.03 M-1 leading to a rate constant of (2.3 ± 0.2) × 106 M-1 s-1 for methanol quenching of product formation. Transient absorption studies show that methanol quenches triplet 1 at pH 11.5 with a rate constant of (1.8 ± 0.1) × 106 M-1 s-1. In the absence of hydroxide, methanol does not quench the triplet state. The results are explained in terms of formation of low concentrations of methoxide in alkaline solution.
Solvent effect on the α-effect: Ground-state versus transition-state effects; a combined calorimetric and kinetic investigation
Um, Ik-Hwan,Hwang, So-Jeong,Buncel, Erwin
, p. 915 - 920 (2006)
In a study of the solvent effect on the α-effect, second-order rate constants (kNu-) have been determined spectrophotometrically for reactions of a series of substituted phenyl acetates with butan-2,3-dione monoximate (Ox-, α-nucleop
A Simple but Efficient Catalytic Approach for the Degradation of Pollutants in Aqueous Media through Cicer arietinum Supported Ni Nanoparticles
Khan, Shahid Ali,Rasool, Shagufta,Rahman, Khaliq Ur,Hussain, Shah,Khan, Inamullah,Ismail, Muhammad,Farooq, Aliya,Khan, Sarzamin,Raza, Mian Ahmad,Asiri, Abdullah Muhammad,Khan, Sher Bahadar
, p. 1789 - 1802 (2019/09/20)
Plant based materials are considered to have broad applications in the remediation of toxic materials. In this report, we present an environmental friendly and economic Cicer arietinum, named as (CP) supported for the synthesis of Ni nanoparticles (NPs) designated as Ni@CP. The in situ Ni@CP NPs were obtained using aqueous medium in the presence of sodium borohydride (NaBH4) as a reducing agent. The prepared catalysts were applied for the hydrogenation/degradation of p-nitrophenol (PNP), o-nitrophenol (ONP), and 2,4-dinitrophenol (DNP), as well as congo red (CR), methyl orange (MO), methylene blue (MB) and rhodamine B (RB) dyes. The amount of total metal ions adsorbed onto the CP was evaluated by flame atomic absorption spectroscopy. The Ni@CP catalyst was characterized through PXRD, FTIR, FESEM and EDX analyses.
High catalytic efficiency of nanostructured β-CoMoO4 in the reduction of the ortho-, meta- and para-nitrophenol isomers
Al-Wadaani, Fahd,Omer, Ahmed,Abboudi, Mostafa,Hassani, Hicham Oudghiri,Rakass, Souad,Messali, Mouslim,Benaissa, Mohammed
, (2018/02/17)
Nanostructured -CoMoO4 catalysts have been prepared via the thermal decomposition of an oxalate precursor. The catalyst was characterized by infrared spectroscopy (FTIR), X-ray diffraction (XRD), Brunauer-Emmett-Teller method (BET), energy dispersive X-ray spectroscopy (EDX), and transmission electron microscopy (TEM). The efficiency of these nanoparticles in the reduction of ortho- and meta-nitrophenol isomers (2-NP, 3-NP, and 4-NP) to their corresponding aminophenols was tested using UV-visible spectroscopy measurements. It was found that, with a -CoMoO4 catalyst, NaBH4 reduces 3-NP instantaneously, whilst the reduction of 2-NP and 4-NP is slower at 8 min. This difference is thought to arise from the lower acidity of 3-NP, where the negative charge of the phenolate could not be delocalized onto the oxygen atoms of the meta-nitro group.
O-nucleophilicity of hydroxamate ions for cleavage of carboxylate and phosphate esters in cationic micelles
Satnami, Manmohan L.,Karbhal, Indrapal,Dewangan, Hitesh K.
supporting information, p. 419 - 432 (2014/07/08)
The nucleophilic reactivities of hydroxamate (HA-) ions of the structure RCONHO- [R = CH3 (acetohydroxamate, AHA -), C6H5 (benzohydroxamate, BHA-), 2-OHC6H4
Kinetic and theoretical study on nucleofugality in the phenolysis of 3-nitrophenyl and 4-nitrophenyl 4-cyanophenyl thionocarbonates
Castro, Enrique A.,Ca?ete, Alvaro,Campodónico, Paola R.,Cepeda, Marjorie,Pavez, Paulina,Contreras, Renato,Santos, José G.
, p. 130 - 135 (2013/07/11)
The phenolysis of 3-nitrophenyl 4-cyanophenyl thionocarbonate (1) and 4-nitrophenyl 4-cyanophenyl thionocarbonate (2) are subjected to a kinetic investigation in order to evaluate the nucleofugality of the corresponding leaving groups. For the reaction of 2 only 4-nitrophenoxide is obtained as leaving group. For the reaction of 1 the nucleofugality ratio 3-nitrophenoxide/4-cyanophenoxide is 1/3 from the corresponding T- intermediate. Theoretical calculations confirm the experimental results. From these results it can be concluded that the non-leaving group affects the nucleofugality ratio.
Kinetics of the reaction of phenyl picrates with phenoxide ions in water. Concerted or stepwise?
Crampton, Michael R.,Robotham, Ian A.
, p. 1084 - 1089 (2014/01/06)
A kinetic study is reported of the exchange reactions of substituted phenoxide ions with some ring-substituted 2,4,6-trinitrophenyl ethers in water. The βronsted diagrams formed by plotting log k, where k is the second-order rate constant for reaction, ve
Nucleophilic substitution reactions of phenyl y-substituted-phenyl carbonates with butane-2,3-dione monoximate and 4-chlorophenoxide: Origin of the α-effect
Kim, Min-Young,Min, Se-Won,Um, Ik-Hwan
, p. 49 - 53 (2013/08/24)
Second-order rate constants have been measured spectrophotometrically for the reactions of phenyl Ysubstituted- phenyl carbonates 7a-g with butane-2,3-dione monoximate (Ox-) in 80 mol % H2O/20 mol % DMSO at 25.0 ± 0.1 °C. The α-nucleophile Ox- is 53-95 times more reactive than the corresponding normalnucleophile 4-ClPhO- toward 7a-g, indicating that the α-effect is operative. The magnitude of the α-effect (e.g., the kOx/k4-ClPhO ratio) is independent of the electronic nature of the substituent Y. The cause of the α- effect for the reactions of 7a-g has been suggested to be ground-state (GS) effect rather than transition-state (TS) stabilization through a six-membered cyclic TS, in which Ox- behaves a general acid/base catalyst. This idea is further supported by the result that OH- exhibits negative deviation from the linear Bronsted-type plot composed of a series of aryloxides, while Ox- deviates positively from the linearity. Differential solvation of the GS of Ox- and 4-ClPhO- has been suggested to be responsible for the α-effect exerted by Ox-.
