- Synthesis method of 2-bromo-5-methoxyphenol
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The invention discloses a synthesis method of 2-bromo-5-methoxyphenol. According to the synthesis method, 3-methoxyphenol is taken as a raw material, firstly, the 3-methoxyphenol reacts with a protection reagent such as tert-butyldimethylsilyl chloride, a
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Paragraph 0046; 0064-0066; 0071-0073; 0100
(2019/10/22)
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- Copper-Catalyzed Acetylation of Electron-Rich Phenols and Anilines
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An approach has been developed for the copper-catalyzed acetylation of phenols and anilines with potassium thioacetate as an acetylating reagent. Although only electron-rich phenols and anilines are compatible with this protocol, the reaction can provide moderate to high yields under mild conditions. Compared with other acetylating reagents, the current reagent has certain advantages, such as its low cost, easy availability, stability, insensitivity to water or air, and ease of storage.
- Zhang, Jieyu,Ke, Qiumin,Tian, Feitao,Jiang, Bei,Ji, Chang-An,Zhang, Lingling,Yu, Jian,Huang, Dayun,Yan, Guobing
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supporting information
p. 726 - 730
(2019/03/26)
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- Ligand-Promoted Palladium-Catalyzed C?H Acetoxylation of Simple Arenes
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The palladium-catalyzed C?H oxidation of simple arenes is an attractive strategy to obtain phenols, which have many applications in the fine chemicals industry. Although some advances have been made in this research area, low reactivity and selectivity are, in general, observed. This report describes a new catalytic system for the efficient C?H acetoxylation of simple arenes based on Pd(OAc)2 and a pyridinecarboxylic acid ligand.
- Valderas, Carolina,Naksomboon, Kananat,Fernández-Ibá?ez, M. ángeles
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p. 3213 - 3217
(2016/10/24)
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- Chelating Bis-N-heterocyclic Carbene-Palladium(II) Complexes for Oxidative Arene C-H Functionalization
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Bis-N-heterocyclic carbene (NHC)-chelated palladium(II) complexes have been synthesized, characterized fully including single-crystal X-ray structural analyses, and utilized for the first time toward catalytic oxidative C-H functionalization of arenes with PhI(OAc)2 and N-bromosuccinimide. (Figure Presented).
- Desai, Sai Puneet,Mondal, Moumita,Choudhury, Joyanta
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p. 2731 - 2736
(2015/06/30)
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- The first vinyl acetate mediated organocatalytic transesterification of phenols: A step towards sustainability
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The present report outlines our efforts toward a simple yet elegant protocol for O-acylation of a wide variety of phenols. This highly enabling and solventless method relies on vinyl acetate as an innocuous acyl donor and DABCO as an organocatalyst. Operational simplicity, excellent yields, higher and faster conversion rates without excess reagents, a simple workup and essentially no need of columns are some of the salient features of the reported protocol.
- Kumar, Manoj,Bagchi, Sourav,Sharma, Anuj
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supporting information
p. 8329 - 8336
(2015/11/10)
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- Rh-Catalyzed Synthesis of Coumarin Derivatives from Phenolic Acetates and Acrylates via C-H Bond Activation
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An efficient annulation strategy involving the reaction of phenolic acetates with acrylates in the presence of [Rh2(OAc)4] as catalyst and formic acid as reducing agent, leading to the high yield synthesis of coumarin derivatives, has been developed. The addition of NaOAc as a base increased the yield of the products. The reaction is quite successful for both electron-rich as well as electron-deficient phenolic acetates, affording coumarins with excellent regioselectivity, and proceeds via C-H bond activation proven by deuterium incorporation studies.
- Gadakh, Sunita K.,Dey, Soumen,Sudalai, Arumugam
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p. 11544 - 11550
(2015/12/04)
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- Acetylation of alcohols and phenols by zinc zirconium phosphate as an efficient heterogeneous catalyst under solvent-free conditions
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An efficient method for the acetylation of a wide range of alcohols as well as phenols with acetic anhydride in good to excellent yields under solvent-free conditions, using zinc zirconium phosphate as the catalyst was investigated. The catalyst was characterized by XRD, inductivity coupled plasma-optical emission spectroscopy, and scanning electron microscope. Products are easily isolated and the protocol is mild and green, compared to the existing methods. Graphical abstract: [Figure not available: see fulltext.]
- Hajipour, Abdol Reza,Karimi, Hirbod,Karimzadeh, Morteza
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p. 1461 - 1472
(2014/09/30)
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- Synthesis and biological evaluation of 4-(1,2,3-triazol-1-yl)coumarin derivatives as potential antitumor agents
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In this research, a series of 4-(1,2,3-triazol-1-yl)coumarin conjugates were synthesized and their anticancer activities were evaluated in vitro against three human cancer cell lines, including human breast carcinoma MCF-7 cell, colon carcinoma SW480 cell and lung carcinoma A549 cell. To increase the biological potency, structural optimization campaign was conducted focusing on the C-4 position of 1,2,3-triazole and the C-6, C-7 positions of coumarin. In addition, to further evaluate the role of 1,2,3-triazole and coumarin for antiproliferative activity, 9 compounds possessing 4-(piperazin-1-yl)coumarin framework and 3 derivatives baring quinoline core were also synthesized. By MTT assay in vitro, most of the compounds display attractive antitumor activities, especially 23. Further flow cytometry assays demonstrate that compound 23 exerts the antiproliferative role through arresting G2/M cell-cycle and inducing apoptosis.
- Zhang, Wenjuan,Li, Zhi,Zhou, Meng,Wu, Feng,Hou, Xueyan,Luo, Hao,Liu, Hao,Han, Xuan,Yan, Guoyi,Ding, Zhenyu,Li, Rui
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supporting information
p. 799 - 807
(2014/02/14)
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- Steric control of site selectivity in the Pd-catalyzed C-H acetoxylation of simple arenes
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This report describes the use of an oxidant and a ligand to control site selectivity in the Pd(OAc)2-catalyzed C-H acetoxylation of simple arenes. The use of MesI(OAc)2 as the terminal oxidant in combination with acridine as the ligand results in primarily sterically controlled selectivity. In contrast, with Pd(OAc)2 as the catalyst and PhI(OAc)2 as the oxidant, electronic effects dominate the selectivity of arene C-H acetoxylation.
- Cook, Amanda K.,Emmert, Marion H.,Sanford, Melanie S.
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supporting information
p. 5428 - 5431
(2013/11/19)
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- Palladium-catalyzed acetoxylation of arenes by novel sulfinyl n-heterocyclic carbene ligand complexes
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A series of novel ligands based on N-heterocyclic carbene and sulfoxide functionalities have been prepared and characterized. Pd(II) complexes have been synthesized by transmetalation from the corresponding NHC-Ag derivatives, and their behavior as catalysts has been studied in arene C-H bond oxidative activation. Studies conducted toward the elucidation of the reaction mechanism of the acetoxylation suggest a C-H activation step at Pd(IV) rather than Pd(II) intermediates.
- Tato, Francisco,Garcia-Dominguez, Andres,Cardenas, Diego J.
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supporting information
p. 7487 - 7494
(2014/04/03)
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- New approach for the construction of the coumarin frame and application in the total synthesis of natural products
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A new synthetic approach is described for building the coumarin scaffold through the Lewis acid-promoted cyclization of novel aryl 3-(dimethylamino)prop- 2-enoates 2a - 2f. The latter precursors were prepared via aminomethylenation of the corresponding aryl acetates 4a - 4f with the Bredereck reagent. This approach was used for the synthesis of biologically active natural compounds 1a - 1f, through a three-step procedure starting from the corresponding phenols.
- Jerezano, Alberto,Jimenez, Fabiola,Del Carmen Cruz, Maria,Montiel, Luisa E.,Delgado, Francisco,Tamariz, Joaquin
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experimental part
p. 185 - 198
(2011/04/17)
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- Isolation and synthesis of flavonols and comparison of their antioxidant activity
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Phytochemical investigation of the leaves of Astragalus beckari yielded four flavonol aglycones, namely kaempferol, quercetin, 5-deoxy kaempferol and fisitin. These isolated compounds were then synthesised in the laboratory using the Algar-Flyn-Oyamad reaction. Antioxidant activity of both the isolated and synthesised flavonoids was compared using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay method. The isolated flavonoids were found to be more active.
- Hasan, Aurangzeb,Sadiq,Abbas,Mughal,Khan, Khalid M.,Ali, Muhammad
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experimental part
p. 995 - 1003
(2010/09/05)
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- Phosphomolybdic acid: Mild and efficient catalyst for acetylation of alcohols, phenols, and amines under solvent-free conditions
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Phosphomolybdic acid (PMA) has been found to be a simple and efficient catalyst for the acetylation of alcohols, phenols, and amines. Acetylation reactions with acetic anhydride (1.0 equiv) proceed in excellent yield in the presence of a catalytic amount (0.2 mol%) of PMA at ambient temperature within a relatively short reaction time (10 min). Structurally diverse alcohols, phenols, and amines undergo acetylation under solvent-free conditions. Georg Thieme Verlag Stuttgart.
- Kadam, Santosh T.,Sung, Soo Kim
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p. 267 - 271
(2008/12/22)
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- Thallium(III) chloride: A mild and efficient catalyst for acylation of alcohols, phenols and thiols, and for geminal diacylation of aldehydes under solvent-free conditions
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Thallium(III) chloride is a simple and efficient catalyst for acylation of alcohols, phenols and thiols. It is also very effective for geminal diacylation of aldehydes. The acylation reaction using acetic anhydride proceeds in excellent yield in the presence of catalytic amounts of thallium(III) chloride (1 mol%) at room temperature within relatively short reaction times (20 min). Structurally diverse alcohols, phenols, thiols and aldehydes undergo acylation under solvent-free conditions.
- Kadam, Santosh T.,Kim, Sung Soo
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experimental part
p. 3307 - 3313
(2009/05/07)
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- Part 148 in the series "studies on novel synthetic methodologies:" Selective acetylation of alcohols, phenols and amines and selective deprotection of aromatic acetates using silica-supported phosphomolybdic acid
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An environmentally friendly silica-supported phosphomolybdic acid was found to be a highly efficient catalyst for the selective acetylation of alcohols, phenols and amines in the absence of any solvent and also for the chemoselective deprotection of aromatic acetates under very mild conditions. This method has been used for the protection of the hydroxy groups as well as for the deprotection of the acetates of several naturally occurring bioactive phenolic compounds. The catalyst can be easily recovered and reused.
- Das, Biswanath,Thirupathi, Ponnaboina,Kumar, Rathod Aravind,Laxminarayana, Keetha
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p. 2677 - 2683
(2008/09/19)
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- Facile and regioselective dealkylation of alkyl aryl ethers using niobium(V) pentachloride
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A simple and facile method for the cleavage of carbon-oxygen bonds promoted by niobium pentachloride(V) is described. Excellent yields and regioselectivities were observed with various alkyl aryl ethers to give the phenols. NMR studies revealed the formation of monoaryloxy niobium salt(V), and a neighboring-group effect may play a significant role in the regioselectivity. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
- Sudo, Yukinori,Arai, Shigeru,Nishida, Atsushi
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p. 752 - 758
(2007/10/03)
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- Novel synthesis, reactivity, and stereochemistry of substituted 3-trifluoromethyl- and 3-perfluoroalkyl-3-phenoxyprop-2-enal
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Substituted 3-phenoxy-3-perfluoroalkylprop-2-enals 3a-s are synthesized in high yields starting from a gem-iodoacetoxy derivative 1 and phenoxides 2. Then efficient syntheses of push-pull derivatives 4, 5, 8a,b, and nonconjugated analogues 6 and 7 illustrate the synthetic potentialities of 3. Stereochemical studies of these perfluoroalkyl-containing trisubstituted olefinic derivatives 3-8b revealed that the 4JCF coupling constant observed in the 13C NMR spectra was crucial in the determination of their configurations and conformations in solution. The solvent polarity effect on the stereochemistry of push-pull compounds 3-5 and 8a,b was studied. Unusual significant medium polarity effect on the stereochemistry of imino enol ether derivative 4 was observed.
- El Kharrat, Salem,Laurent, Philippe,Blancou, Hubert
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p. 6742 - 6752
(2007/10/03)
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- Molecular iodine in isopropenyl acetate (IPA): a highly efficient catalyst for the acetylation of alcohols, amines and phenols under solvent free conditions
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Iodine in isopropenyl acetate (IPA) is a highly efficient catalyst for the acetylation of a variety of alcohols, phenols and amines under solvent free conditions. Primary, secondary, tertiary alcohols, amines and mono to polyhydroxy phenols and anilines with electron donating or withdrawing substituents can be easily acetylated in good to excellent yield at 85-90 °C.
- Ahmed, Naseem,van Lier, Johan E.
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p. 5345 - 5349
(2007/10/03)
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- Synthesis of methoxy-substituted phenols by peracid oxidation of the aromatic ring
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A novel benign protocol for the preparation of hydroxy-methoxybenzene derivatives is disclosed. By utilizing this protocol, activated aromatic compounds such as l,3-dimethoxy-2-methyl-benzene and 1-(2,6-dimethoxyphenyl) ethanone are smoothly converted to the corresponding monohydroxylated compound. The reaction can be considered to be a normal aromatic electrophilic substitution reaction, and the regioselectivity for the reaction thus follows the similar rules as for electrophilic substitutions. The protocol is composed by benign reagents, namely, hydogenperoxide, acetic acid, and p-toluene sulfonic acid, which lead to the production of ethaneperoxoic acid in situ. The ethaneperoxoic acid operates as the hydroxylating reagent. The hydroxylation reaction is completed within a short period and requires moreover only mild experimental conditions, which make this novel protocol a green, cheap, and rapid process leading to hydroxy-methoxybenzene derivatives. The proposed reaction mechanism is supported by density functional theory and NMR spectroscopy experiments. The mechanism is constituted by two discrete steps: (a) addition of OH+ to the most nucleophilic carbon atom of the aromatic ring, which is the rate-determining step, and (b) the loss of the proton from the aromatic ring.
- Bjorsvik, Hans-Rene,Occhipinti, Giovanni,Gambarotti, Cristian,Cerasino, Leonardo,Jensen, Vidar R.
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p. 7290 - 7296
(2007/10/03)
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- Determination of aromaticity indices of thiophene and furan by nuclear magnetic resonance spectroscopic analysis of their phenyl esters
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A series of m- and p-substituted phenyl benzoates, 2-thienoates, and 2-furoates were prepared and their 1H and 13C nmr spectroscopic characteristics were examined. In general, good correlations were observed between the chemical shift values of protons and carbons of the acyl aromatic rings and the Hammett σ. Plots of the chemical shift values of the carbonyl carbons of the benzoates against those of the 2-thienoates and 2-furoates gave an excellent correlation and the values of the slopes are 0.85 and 0.75, respectively, in dimethyl sulfoxide-d6 and 0.90 and 0.78, respectively, in chloroform-d. The values could be considered as a set of aromaticity indices.
- Lee, Chang Kiu,Yu, Ji Sook,Lee, Hye-Jin
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p. 1207 - 1217
(2007/10/03)
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- Acetylation of phenols in organic solvent catalyzed by a lipase from chromobacterium viscosum
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Lipase from Chromobacterium viscosum, absorbed on an inert support, was employed as catalyst for the esterification of monohydric phenols in organic solvent, with vinyl acetate as acyl donor. The effect of aromatic ring substitution on the initial rate of transesterification was investigated.
- Nicolosi,Piatelli,Sanfilippo
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p. 2477 - 2482
(2007/10/02)
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- Substituent Effect in o-Nitroperbenzoic Acid Oxidation of m- and p-Substituted Acetophenones
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The Baeyer-Villiger reaction of m- and p-substituted acetophenones (substituents: H, p-MeO, p-t-Bu, p-i-Pr, p-Et, p-Me, p-Cl, p-Br, m-MeO, m-Me, m-Cl) with o-nitroperbenzoic acid was studied in chloroform at 30 deg C.The rate constants for the general acid catalysis were measured at several concentrations of o-nitrobenzoic acid which acted as an acid catalyst.The uncatalyzed and acid-catalyzed rate constants obtained afforded ρ values of -2.16 and -4.11 with ?, respectively.The results indicated that the rate-determining step is the migration of the phenyl group in the peroxy acid-carbonyl adduct for all the substituents studied, whether the reaction is acid-catalyzed or not, and that the acid catalyst intervenes only in the formation of the acid-ketone adduct in the initial state and not in the migration step.The variation of the leaving group abilities required the variation of the substituent constants applied, whereas the acid intervention in the addition step was reflected only in the variation of the ρ value, not in the substituent constants to be applied.The smaller resonance demand for o-nitrobenzoic acid indicated that the structure of the transition state in the migration step was looser and that the position of the transition state was earlier than those for m-chloroperbenzoic acid.
- Token, Katsuo,Hirano, Kenji,Yokoyama, Tai,Goto, Katsumi
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p. 2766 - 2771
(2007/10/02)
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- Metal Ion Oxidation. XI. Oxidation of Aromatic Hydroarbons and Arylacetic Acids by Heteropoly Anions Containing Ni(IV), Mn(IV) and Co(III) Ions as Central Atoms
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Heteropoly ions containing Ni(IV) and Mn(IV) as central atoms have been shown to oxidize aromatic hydrocarbons and arylacetic acids in acetic acid and acetic acid-water, yielding acetates and alcohols.The product patternof these reactions supports an outer-sphere electron transfer mechanism.Substituted arylacetic acids are decarboxylated when treated with 12-tungstocobalt(III)ate ion and 9-molybdonickel(IV)ate ion.These decarboxylation reactions are proposed to be outer-sphere electron transfer processes.
- Joensson, Lennart
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p. 761 - 768
(2007/10/02)
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- Nucleophilicity of Phenolates in the Reaction with p-Nitrophenyl Acetate in Ethanol
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The rate of release of p-nitrophenol in the reaction of nine substituted phenolates with p-nitrophenyl acetate has been determined by spectrophotometric measurements in absolute ethanol at 22 deg C.The phenolate anion is the reactive species and competes with ethoxide anion, arising from solvolysis of the phenolate, for nucleophilic attack on the ester carbonyl carbon atoms.From the observed reaction rates the solvolysis constants and the pKa values of the phenols were obtained.The second-order rate constants for phenoxide anions were correlated with the pKa values of the corresponding phenols giving a Broensted β value of 0.57.A comparison with the nucleophilic reactivity of arenethiolates towards the same substrate in ethanol has been made.The rate-determining step is probably the expulsion of the leaving group in the raection of arenethiolates, whereas it is the nucleophile attack in the reaction of phenoxides.
- Guanti, Giuseppe,Cevasco, Giorgio,Thea, Sergio,Dell'Erba, Carlo,Petrillo, Giovanni
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p. 327 - 330
(2007/10/02)
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- Metal Ion Oxidation. VII. Oxidation of Aromatic Hydrocarbons by Potassium 12-Wolframocobalt(III)ate, a "Soluble Anode"
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The oxidation of aromatic compounds with potassium 12-wolframocobalt(II)ate in acetic acid media has been investigated.A wide range of alkylaromatics can be acetoxylated in the α position, whereas nuclear substitution can be effected in the presence of acetate ion.In a few cases acetoxymethylation is observed, presumably via intermediate arylacetic acid. 4-Fluoroanisole is converted to 4-acetoxyanisole.In all preparative aspects, the reaction is closely similar to anodic and Ag(II) mediated acetoxylation.A study of substituted effects upon α acetoxylation showed a good linear relationship between log krel and Eo for oxidation of the alkylaromatic substrates (slope -3.2 V-1).A strong deuterium isotope effect (KH/kD ca. 6) is indicative of a rate-determining step involving hydrogen atom transfer ("concerted electron/proton transfer") from the α C-H bond to an oxygen of the heteropoly ion.
- Eberson, Lennart,Wistrand, Lars-Goeran
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p. 349 - 358
(2007/10/02)
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