Xn:Harmful;
135-19-3Relevant articles and documents
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Maikopar
, (1869)
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Effect of cyclodextrin complexation on photo-fries rearrangement of naphthyl esters
Banu, Habeeb Shayira,Pitchumani, Kasi,Srinivasan, Chockalingam
, p. 9601 - 9610 (1999)
Photolysis of β-cyclodextrin inclusion complexes of 1- and 2-naphthyl esters (acetates and benzoates) in aqueous medium, results in rearrangement to give one isomer of acylnaphthol in excess, whereas the solid state irradiation of the cyclodextrin complexes yields selectively one isomer. In addition, formation of cleavage product is totally suppressed. This remarkable selectivity is attributed to specific modes of the complexation of the esters into the β-CD cavity.
Regio- and stereochemistry of Na-mediated reductive cleavage of alkyl aryl ethers
Azzena, Ugo,Carraro, Massimo,Meloni, Claudia,Murgia, Irene,Pisano, Luisa,Pittalis, Mario,Luisi, Renzo,Musio, Biagia,Degennaro, Leonardo
, p. 1550 - 1554 (2014)
We have investigated the regio-and stereochemistry of the reductive dealkoxylation of alkyl aryl ethers. Chiral non-racemic secondary alcohols were converted into the corresponding m-terphenyl or 2-biphenyl ethers either via inversion of configuration under Mitsunobu reaction conditions or with retention of configuration under SNAr conditions. The successive cleavage of the aromatic C-O bond occurred in the presence of a stoichiometric amount of Na metal in dry tetrahydrofuran at rt with retention of configuration, thus highlighting that the overall inversion or retention of configuration for the whole two-step procedure is dictated by the stereochemistry of the first synthetic step.
Synthesis, structures and inclusion properties of tetranaphthalides: New macrocyclic clathrate hosts
Tanaka, Koichi,Hori, Kyosuke,Masumoto, Asuka,Arakawa, Ryuichi,Caira, Mino R.
, p. 2911 - 2915 (2011)
Novel tetranaphthalide host compounds 3 and 4 bearing isomeric naphthalene moieties have been synthesized and their inclusion properties were investigated. These host compounds enclathrated several kinds of ketones, cyclic ethers, amides, sulfoxides and aromatic compounds. The structures of two representative inclusion compounds containing different host molecules and a common guest (dimethyl sulfoxide) were investigated by X-ray diffraction to determine the nature of guest inclusion and to rationalize their distinctly different thermal decomposition profiles.
Decarbethoxylative Arylation Employing Arynes: A Metal-Free Pathway to Arylfluoroamides
Gupta, Ekta,Kant, Ruchir,Mohanan, Kishor
, p. 6016 - 6019 (2017)
An efficient, metal-free decarbethoxylative arylation protocol for the synthesis of α-aryl-α-fluoroamides from fluoromalonamates, under ambient reaction conditions using aryne as an electrophilic arylating agent, is reported. This decarbethoxylative arylation proceeds under mild conditions and provides a practical and effective entry to a wide range of α-aryl-α-fluoroacetamides. Interestingly, the use of the tert-butyl ester of fluoromalonamate prevented the otherwise rapid decarboxylation step, affording the arylated fluoromalonamate in moderate yield.
Cationic reverse micelles create water with super hydrogen-bond-donor capacity for enzymatic catalysis: Hydrolysis of 2-naphthyl acetate by α-Chymotrypsin
Moyano, Fernando,Falcone, R. Falcone,Mejuto,Silber, Juana J.,Correa, N. Mariano
, p. 8887 - 8893 (2010)
Reverse micelles (RMs) are very good nanoreactors because they can create a unique microenvironment for carrying out a variety of chemical and biochemical reactions. The aim of the present work is to determine the influence of different RM interfaces on the hydrolysis of 2-naphthyl acetate (2NA) by α-chymotrypsin (α-CT). The reaction was studied in water/benzyl-nhexadecyldimethylammonium chloride (BHDC)/benzene RMs and, its efficiency compared with that observed in pure water and in sodium 1,4-bis-2-ethylhexylsulfosuccinate (AOT) RMs. Thus, the hydrolysis rates of 2-NA catalyzed by α-CT were determined by spectroscopic measurements. In addition, the method used allows the joint evaluation of the substrate partition constant Kp between the organic and the micellar pseudophase and the kinetic parameters: catalytic rate constant kcat, and the Michaelis constant KM of the enzymatic reaction. The effect of the surfactant concentration on the kinetics parameters was determined at constant W 0= [H2O]/[surfactant], and the variation of W0 with surfactant constant concentration was investigated. The results show that the classical Michaelis-Menten mechanism is valid for α-CT in all of the RMs systerns studied and that the reaction takes place at both RM interfaces. Moreover, the catalytic efficiency values kcat/KM obtained in the RMs systems are higher than that reported in water. Furthermore, there is a remarkable increase in α-CT efficiency in the cationic RMs in comparison with the anionic system, presumably due to the unique water properties found in these confined media. The results show that in cationic RMs the hydrogen-bond donor capacity of water is enhanced due to its interaction with the cationic interface. Hence, entrapped water can be converted into "super-water" for the enzymatic reaction studied in this work.
A novel application of Hβ-zeolite in catalytic dehalogenation of halophenols
Adimurthy, Subbarayappa,Ramachandraiah, Gadde,Bedekar, Ashutosh V.
, p. 6391 - 6392 (2003)
A new application of Hβ-zeolite for debromination of bromophenols and deiodination of iodophenols is presented in this note. The heterogeneous catalyst can be recovered and recycled effectively for subsequent reactions. The catalyst was found ineffective for similar action on chlorophenols.
Pharmacokinetics of 2-naphthol following intrapericardial administration, and formation of 2-naphthyl-β-D-glucoside and 2-naphthyl sulphate in the American lobster, Homarus americanus
Li,James
, p. 609 - 626 (1997)
1. Following a 0.25-mg/kg intrapericardial dose of the phenolic compound, 2-naphthol, to the American lobster, Homarus americanus, a two-compartment model best described the disposition of parent [14C]-2-naphthol in the haemolymph. Male and female lobsters had similar α-phase half lives of 26 ± 19 min (mean ± SD, n = 4) and 29 ± 15 min respectively. The β-phase half lives were significantly longer in males, 63.9 ± 30.9 h, than in females, 30.6 ± 6.8 h (P -1 x kg-1 and was higher than that of males, 11.1 ± 5.9 ml x h-1 x kg-1 (p 99% bound to haemolymph proteins at 1 min find > 90% bound at 1 day after the dose, indicating that both 2-naphthol and 2-naphthyl-β-D-glucoside were highly protein bound. 4. 2-Naphthyl-β-D-glucoside was slowly eliminated from haemolymph in both males and females, with elimination half lives of 34-78 h. 2-Naphthyl-β-D-glucoside was the major metabolite in urine samples collected at 5 days after the dose. Hepatopancreas and antennal gland contained glucosidase activities, and the long half life of 2-naphthyl-β-D-glucoside could be explained by conjugation-deconjugation cycling. 5. 2-Naphthyl sulphate was eliminated from haemolymph with a half-life 10 h and was excreted in urine.
The reduction of graphene oxide with hydrazine: elucidating its reductive capability based on a reaction-model approach
Chua, Chun Kiang,Pumera, Martin
, p. 72 - 75 (2016)
We have performed an experimental investigation on the effects of hydrazine treatment on graphene oxide via a reaction-model approach. Hydrazine was reacted with small conjugated aromatic compounds containing various oxygen functional groups to mimic the structure of graphene oxide. The hydroxyl and carboxylic groups were not readily removed while carbonyl groups reacted with hydrazine to form the corresponding hydrazone complexes. In the presence of adjacent hydroxyl groups, carboxyl groups underwent thermal decarboxylation.
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Soffer et al.
, p. 1556 (1952)
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Mechanistic Insights into Hydrogen Evolution by Photocatalytic Reforming of Naphthalene
Al-Madanat, Osama,Alsalka, Yamen,Bahnemann, Detlef W.,Curti, Mariano,Dillert, Ralf
, p. 7398 - 7412 (2020)
Heterogeneous photocatalysis has been widely considered, among other applications, for environmental remediation and hydrogen production. While these applications have been traditionally seen as well-separated areas, recent examples have highlighted the possibility of coupling them. Here, we demonstrate the simultaneous production of H2 and naphthalene removal from aqueous solutions with (unoptimized) photonic efficiencies of 0.97 and 0.33percent, respectively, over Pt-TiO2 under simulated sunlight. Photocatalytic and spin-trapping experiments in the presence of a hydroxyl radical and hole scavengers evinced that only the photogenerated holes play a significant role in the oxidation of naphthalene. Isotopic labeling analyses showed that the evolved H2 isotopologues match those of the solvent and that deuterated water (but not deuterated naphthalene) decreases the reaction rate, suggesting its involvement in the rate-determining step. Moreover, the use of Ti18O2 does not lead to the significant formation of 18O-enriched CO2, suggesting that water is the source of the oxygen atoms. Ultimately, by considering the stable and transient reaction intermediates, we propose a plausible reaction pathway. Our work illustrates that environmental remediation can be effectively coupled to solar fuel production, providing a double purpose to photocatalytic reactions, while the mechanistic insights will be of use for the further development of this strategy.
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Linstead,Michaelis
, p. 1134,1138 (1940)
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Formation of naphthalene hydrates in the enzymatic conversion of 1,2-dihydronaphthalene by two fungal peroxygenases and subsequent naphthalene formation
Kluge, Martin,Ullrich, Rene,Scheibner, Katrin,Hofrichter, Martin
, p. 56 - 60 (2014)
The formation of naphthalene hydrates (i.e. 1- and 2-hydroxy-1,2- dihydronaphthalene) displays a new activity (besides epoxidation) in the enzymatic transformation of 1,2-dihydronaphthalene by two fungal unspecific peroxygenases (UPOs) accounting for 16-19% of the overall turnover. These arene hydrates decayed into naphthalene that in turn was converted by UPOs into naphthols. The oxygen transferred during hydroxylation was shown to derive from hydrogen peroxide proving a true peroxygenation reaction.
Novel spectral manipulations for determinations of Tolnaftate along with related toxic compounds: Drug profiling and a comparative study
Emam, Raghda A.,Abdelrahman, Maha M.,Abdelaleem, Eglal A.,Ali, Nouruddin W.
, (2019)
A comparative study using novel quadruple divisor and mean centering of ratio spectra spectrophotometric methods was developed for resolution of five- component mixture of Tolnaftate, β-naphthol (Tolnaftate alkaline degradation product and its toxic impurity), methyl(m-tolyl)carbamic acid (Tolnaftate alkaline degradation product), N-methyl-m-toluidine (Tolnaftate toxic impurity) and methyl paraben (as a preservative). For the novel quadruple divisor method, each component in the quinary mixture was determined by dividing the quinary mixture spectrum by a sum of standard spectrum of equal concentration of the other four components as a quadruple divisor. First derivative of each ratio spectra was then obtained which allowed selective determination of each component without interference from other components in the mixture. The second method was mean centering of ratio spectra that depended on utilizing the mean centered ratio spectra in four successive steps leading to enhancement of the signal to noise ratio. The absorption spectra of the five studied components were recorded in the wavelength range of 210–350 nm. The mean centered fourth ratio spectra amplitudes for each component were used for its determination. The developed methods were successfully applied for determination of laboratory prepared quinary mixtures to ensure method's specificity, then, were further applied on Tinea Cure cream where no interference from excipients. For the first time, Tolnaftate was determined along with its toxic impurity; β-naphthol, that could be absorbed by the skin, causing systemic toxic effects, unlike Tolnaftate that poorly absorbed, indicating the significance of this work. The proposed methods were statistically compared with each other and with the reference method. Furthermore, ICH guidelines were followed for their validation.
Mechanistic imperatives for catalysis of aldol addition reactions: Partitioning of the enolate intermediate between reaction with bronsted acids and the carbonyl group
Richard, John P.,Nagorski
, p. 4763 - 4770 (1999)
The lyoxide ion catalyzed intramolecular aldol addition reaction of 2- (2-oxopropyl)benzaldehyde (1) to give the aldol adduct 3 proceeds via essentially irreversible formation of the acetone-like enolate intermediate 2, because reprotonation of 2 by a solvent of H2O or D2O (k(HOH) or k(DOD)) is much slower than intramolecular addition of the enolate to the carbonyl group (k(c)). The aldol addition reaction of 1 catalyzed by high concentrations of 3-substituted quinuclidine buffers proceeds via reversible deprotonation of 1 to give the enolate 2, and rate-determining addition of the enolate to the carbonyl group. A rate constant ratio of k(c)/k(HOH) = 35 was determined for partitioning of the enolate 2 between intramolecular addition to the carbonyl group and protonation by solvent water. The corresponding ratios k(BH)/k(c) (M-1) for the protonation of 2 by Bronsted buffer acids and intramolecular aldol addition increase from 7 to 450 as the acidity of the buffer acid is increased from pK(BH) = 11.5 to 7.5. The data show that the electrophilic reactivity of the benzaldehyde carbonyl group toward intramolecular addition of the enolate 2 is the same as that of a hypothetical tertiary ammonium cation of pK(BH) = 13.3. The Marcus intrinsic barrier for addition of the enolate 2 to the carbonyl group is unexpectedly small, which suggests that the transition state for this reaction is stabilized by interactions between the soft-soft acid-base pair. The relevance of this work to chemical and enzymatic catalysis of aldol condensation reactions is discussed.
UEBER DIE REAKTION VON α- UND β-TETRALON MIT KALIUMSUPEROXID
Lissel, Manfred
, p. 2213 - 2214 (1984)
The reaction of α- and β-tetralone with potassium superoxide is described.In addition to 2-hydroxy-1,4-naphthoquinone α-naphthol is formed from α-tetralone and β-naphthol and 2-carboxy-benzenepropionic acid from β-tetralone.
Acid-Catalyzed Versus Thermally Induced C1-C1′ Bond Cleavage in 1,1′-Bi-2-naphthol: An Experimental and Theoretical Study
Genaev, Alexander M.,Shchegoleva, Lyudmila N.,Salnikov, George E.,Shernyukov, Andrey V.,Shundrin, Leonid A.,Shundrina, Inna K.,Zhu, Zhongwei,Koltunov, Konstantin Yu.
, p. 7238 - 7243 (2019)
Experiments show that 1,1′-bi-2-naphthol (BINOL) undergoes facile C1-C1′ bond cleavage under action of triflic acid at temperatures above 0 °C to give mainly 2-naphthol along with oligomeric material. CASSCF and MRMP//CASSCF computations have demonstrated unambiguously that this unusual mode of scission of the biaryl bond can occur in the C1,C1′-diprotonated form of BINOL via a mechanism involving homolytic cleavage prompted by the intramolecular electrostatic repulsion. These findings also provide insights into the mechanism of a comparatively easy thermal cleavage of BINOL, implying the intermediacy of its neutral diketo form.
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Kotlarek
, p. 67 (1973)
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Coordination of manganese porphyrins on amino-functionalized MCM-41 for heterogeneous catalysis of naphthalene hydroxylation
Yang, Fu,Gao, Shuying,Xiong, Cuirong,Wang, Haiqing,Chen, Jin,Kong, Yan
, p. 1035 - 1041 (2015)
The different amounts of [5,10,15,20-tetrakis-(pentafluorophenyl)porphyrin] manganese chloride (TF20PPMnCl) were immobilized on amino-functionalized MCM-41 for catalysis of the hydroxylation of naphthalene. The samples were characterized by X-ray powder diffraction, N2 adsorption/desorption isotherms, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, diffuse reflectance ultraviolet-visible spectroscopy, thermogravimetric and differential scanning calorimetry, and inductively coupled plasma mass spectrometry. The results indicated that the manganese porphyrins were axially coordinated on amino-functionalized MCM-41. The prepared samples showed remarkable catalytic activity in the hydroxylation of naphthalene with meta-chloroperbenzoic acid as the oxidant. The catalyst could be reused several times without loss of its activity.
Atropselective hydrolysis of chiral BiNoL-phosphate esters catalyzed by the phosphotriesterase from Sphingobium sp. TCM1
Xiang, Dao Feng,Narindoshvili, Tamari,Raushel, Frank M.
, p. 4463 - 4469 (2020)
The phosphotriesterase from Sphingobium sp. TCM1 (Sb-PTE) is notable for its ability to hydrolyze a broad spectrum of organophosphate triesters, including organophosphorus flame retardants and plasticizers such as triphenyl phosphate and tris(2-chloroethyl) phosphate that are not substrates for other enzymes. This enzyme is also capable of hydrolyzing any one of the three ester groups attached to the central phosphorus core. The enantiomeric isomers of 1,1′-bi-2-naphthol (BINOL) have become among the most widely used chiral auxiliaries for the chemical synthesis of chiral carbon centers. PTE was tested for its ability to hydrolyze a series of biaryl phosphate esters, including mono- and bis-phosphorylated BINOL derivatives and cyclic phosphate triesters. Sb-PTE was shown to be able to catalyze the hydrolysis of the chiral phosphate triesters with significant stereoselectivity. The catalytic efficiency, kcat/Km, of Sb-PTE toward the test phosphate triesters ranged from ～10 to 105 M?1 s?1. The product ratios and stereoselectivities were determined for four pairs of phosphorylated BINOL derivatives.
Effect of Confinement on the Properties of Sequestered Mixed Polar Solvents: Enzymatic Catalysis in Nonaqueous 1,4-Bis-2-ethylhexylsulfosuccinate Reverse Micelles
Durantini, Andres M.,Falcone, R. Dario,Silber, Juana J.,Correa, N. Mariano
, p. 1678 - 1685 (2016)
The influence of different glycerol, N,N-dimethylformamide (DMF) and water mixtures encapsulated in 1,4-bis-2-ethylhexylsulfosuccinate (AOT)/n-heptane reverse micelles (RMs) on the enzymatic hydrolysis of 2-naphthyl acetate by α-chymotrypsin is demonstrated. In the case of the mixtures with DMF and protic solvents it has been previously shown, using absorption, emission and dynamic light-scattering techniques, that solvents are segregated inside the polar core of the RMs. Protic solvents anchor to the AOT, whereas DMF locates to the polar core of the aggregate. Thus, DMF not only helps to solubilize the hydrophobic substrate, increasing its effective concentrations but surprisingly, it does not affect the enzyme activity. The importance of ensuring the presence of RMs, encapsulation of the polar solvents and the corrections by substrate partitioning in order to obtain reliable conclusions is highlighted. Moreover, the effect of a constrained environment on solvent–solvent interactions in homogenous media and its impact on the use of RMs as nanoreactors is stressed.
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Harrison
, p. 616 (1969)
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A mild and practical method for deprotection of aryl methyl/benzyl/allyl ethers with HPPh2andtBuOK
Pan, Wenjing,Li, Chenchen,Zhu, Haoyin,Li, Fangfang,Li, Tao,Zhao, Wanxiang
, p. 7633 - 7640 (2021/09/22)
A general method for the demethylation, debenzylation, and deallylation of aryl ethers using HPPh2andtBuOK is reported. The reaction features mild and metal-free reaction conditions, broad substrate scope, good functional group compatibility, and high chemical selectivity towards aryl ethers over aliphatic structures. Notably, this approach is competent to selectively deprotect the allyl or benzyl group, making it a general and practical method in organic synthesis.
Mn(III) active site in hydrotalcite efficiently catalyzes the oxidation of alkylarenes with molecular oxygen
Wang, Anwei,Zhou, WeiYou,Sun, Zhonghua,Zhang, Zhong,Zhang, Zhihui,He, MingYang,Chen, Qun
, (2020/12/07)
Developing efficient heterogeneous catalytic systems based on easily available materials and molecular oxygen for the selective oxidation of alkylarenes is highly desirable. In the present research, NiMn hydrotalcite (Ni2Mn-LDH) has been found as an efficient catalyst in the oxidation of alkylarenes using molecular oxygen as the sole oxidant without any additive. Impressive catalytic performance, excellent stability and recyclability, broad applicable scope and practical potential for the catalytic system have been observed. Mn3+ species was proposed to be the efficient active site, and Ni2+ played an important role in stabilizing the Mn3+ species in the hydrotalcite structure. The kinetic study showed that the aerobic oxidation of diphenylmethane is a first-order reaction over Ni2Mn-LDH with the activation energy (Ea) and pre-exponential factor (A0) being 85.7 kJ mol?1 and 1.8 × 109 min?1, respectively. The Gibbs free energy (ΔG≠) was determined to be -10.4 kJ mol-1 K-1 for the oxidation based on Eyring-Polanyi equation, indicating the reaction is exergonic. The mechanism study indicated that the reaction proceeded through both radical and carbocation intermediates. The two species were then trapped by molecular oxygen and H2O or hydroxyl species, respectively, to yield the corresponding products. The present research might provide information for constructing highly efficient and stable active site for the catalytic aerobic oxidation based on available and economic material.
