- A Convenient and Stable Heterogeneous Nickel Catalyst for Hydrodehalogenation of Aryl Halides Using Molecular Hydrogen
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Hydrodehalogenation is an effective strategy for transforming persistent and potentially toxic organohalides into their more benign congeners. Common methods utilize Pd/C or Raney-nickel as catalysts, which are either expensive or have safety concerns. In this study, a nickel-based catalyst supported on titania (Ni-phen@TiO2-800) is used as a safe alternative to pyrophoric Raney-nickel. The catalyst is prepared in a straightforward fashion by deposition of nickel(II)/1,10-phenanthroline on titania, followed by pyrolysis. The catalytic material, which was characterized by SEM, TEM, XRD, and XPS, consists of nickel nanoparticles covered with N-doped carbon layers. By using design of experiments (DoE), this nanostructured catalyst is found to be proficient for the facile and selective hydrodehalogenation of a diverse range of substrates bearing C?I, C?Br, or C?Cl bonds (>30 examples). The practicality of this catalyst system is demonstrated by the dehalogenation of environmentally hazardous and polyhalogenated substrates atrazine, tetrabromobisphenol A, tetrachlorobenzene, and a polybrominated diphenyl ether (PBDE).
- Anwar, Muhammad,Beller, Matthias,Dastgir, Sarim,Junge, Kathrin,Leonard, David K.,Ryabchuk, Pavel
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- Ni-Catalyzed Reductive Cyanation of Aryl Halides and Phenol Derivatives via Transnitrilation
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Herein, we report a Ni-catalyzed reductive coupling for the synthesis of benzonitriles from aryl (pseudo)halides and an electrophilic cyanating reagent, 2-methyl-2-phenyl malononitrile (MPMN). MPMN is a bench-stable, carbon-bound electrophilic CN reagent that does not release cyanide under the reaction conditions. A variety of medicinally relevant benzonitriles can be made in good yields. Addition of NaBr to the reaction mixture allows for the use of more challenging aryl electrophiles such as aryl chlorides, tosylates, and triflates. Mechanistic investigations suggest that NaBr plays a role in facilitating oxidative addition with these substrates.
- Mills, L. Reginald,Graham, Joshua M.,Patel, Purvish,Rousseaux, Sophie A. L.
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supporting information
p. 19257 - 19262
(2019/12/02)
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- Search for a photoinduced (site-selective) cleavage of the Ar-Cl bond in dichloroanisoles
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The site-selective cleavage of an Ar-X bond in polyhalogenated aromatics is an important tool in synthetic planning especially when more than one identical halogen atom is present. An alternative to the usual metal-catalyzed cleavage is represented by photochemistry although only a few examples have been reported. We then investigated the feasibility of the site-selective photodechlorination of some dichloroanisoles through a combined experimental and computational study. In the case of 2,4-dichloroanisole, selective detachment of the chlorine atom at the ortho position with respect to the OMe group was observed upon photohomolysis (in cyclohexane) or photoheterolysis (in MeOH) of the Ar-Cl bond. In the latter case, 5-chloro-2-methoxy-1,1′-biphenyl was exclusively formed upon reaction of the resulting phenyl cation with benzene. The substitution of an OH group for a OMe group was detrimental since a lower photoreactivity resulted with no improvement in the selectivity.
- Raviola, Carlotta,Fagnoni, Maurizio
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p. 107 - 117
(2018/02/06)
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- A highly efficient heterogeneous copper-catalyzed chlorodeboronation of arylboronic acids leading to chlorinated arenes
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A highly efficient heterogeneous copper-catalyzed chlorodeboronation of arylboronic acids with inexpensive N-chlorosuccinimide (NCS) was achieved in MeCN in the presence of 10 mol% of l-proline-functionalized MCM-41-immobilized copper(i) complex [MCM-41-l-proline-CuCl] under mild conditions, yielding a variety of aryl chlorides in excellent yields. This method proved to be tolerant of a broad range of functional groups and particularly useful for the conversion of electron-deficient arylboronic acids to aryl chlorides, a transformation that is inefficient without copper catalysis. This heterogeneous copper catalyst can be recovered by a simple filtration of the reaction solution and recycled for at least 10 times without any decreases in activity.
- He, Wen,Zhang, Rongli,Cai, Mingzhong
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p. 764 - 770
(2017/01/13)
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- Functionalised [(NHC)Pd(allyl)Cl] complexes: Synthesis, immobilisation and application in cross-coupling and dehalogenation reactions
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A novel NHC–palladium(II) (NHC?=?N-heterocyclic carbene) complex and its immobilised version have been prepared and fully characterised. Optimisation studies led to good catalytic activities in Suzuki-Miyaura cross coupling and chloroarene dehalogenation reactions. Furthermore, the unexpected palladium-mediated transfer hydrogenation of a carbonyl compound is reported.
- Collinson, John-Michael,Wilton-Ely, James D.E.T.,Díez-González, Silvia
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- Radiolabeling of aromatic compounds using K[*Cl]Cl and OXONE
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We report a novel labeling method for the rapid radiochlorination of aromatic compounds using no-carrier-added short-half-life radioactive chloride ions ([38,39Cl]Cl- and [34mCl]Cl-) and OXONE (Sigma-Aldrich, Japan) as an oxidation reagent. The reaction of radioactive chloride ions with anisole in the presence of OXONE gave a mixture of p-[*Cl]chloroanisole and o-[*Cl]-chloroanisole, with a radiochemical conversion yield of more than 85% (not decay corrected) and selectivity of 7:3, within 10 min. Regioselective radioactive chlorination was achieved by chlorodestannylation of tributylstannyl compounds to afford the corresponding radiochlorinated compounds (p-chloroanisole and m-chloroanisole) in satisfactory radiochemical yields (80-95% and 46-65%, respectively). Copyright
- Takada, Yuuki,Hanyu, Masayuki,Nagatsu, Kotaro,Fukumura, Toshimitsu
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p. 383 - 386,4
(2020/08/24)
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- Novel analogues of ketamine and phencyclidine as NMDA receptor antagonists
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The identification of structurally novel analogues of ketamine and phencyclidine (PCP), as NMDA receptor antagonists, with low to moderate potency at GluN2A and GluN2B receptors is discussed. In particular, some examples, such as compounds 6 and 10, shows decreased calculated lipophilicity, when compared to PCP, while retaining moderate activity. Moreover, the germinal aryl amino substituted lactam ring, as exemplified in compounds 7-10 and 11-13, constitutes a novel scaffold with potential application in the design of biologically active compounds.
- Zarantonello, Paola,Bettini, Ezio,Paio, Alfredo,Simoncelli, Chiara,Terreni, Silvia,Cardullo, Francesco
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scheme or table
p. 2059 - 2063
(2011/04/24)
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- Gold-catalysis: Reactions of organogold compounds with electrophiles
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Different arylgold(I), one alkynylgold(I), and one vinylgold(I) triphenylphosphane complexes were subjected to electrophilic halogenation reagents. With N-chlorosuccinimid, N-bromosuccinimid, and N-iodosuccinimid as well as the Barluenga reagent, selectively halogenated compounds were obtained. Trifluoroacetic acid, as a source of protons, leads to a clean protodeauration. With N-fluorobenzenesulfonimide or Selectfluor, exclusively a homocoupling was observed. For the precursor of the vinylgold(I) complex, a similar oxidative coupling could be induced by gold(III) chloride. Reactions with silicon or tin electrophiles failed. CSIRO 2010.
- Hashmi, A. Stephen K.,Ramamurthi, Tanuja Dondeti,Todd, Matthew H.,Tsang, Althea S.-K.,Graf, Katharina
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experimental part
p. 1619 - 1626
(2011/09/12)
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- Catalytic Friedel-Crafts acylation of aromatic ethers using Sml3
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10% mol Sml3 catalysed the Friedel-Crafts acylation of aromatic ethers by acyl chlorides in acetonitrile with the yields of 48-82%. Reactions of various substituted aromatic ethers with acyl chloride were studied. The structures of compounds were established by IR and 1H NMR. The main product obtained with anisole is the para-substituted compound with only a trace (3, a pattern repeated with the other aromatic ethers used.
- Chen, Xiaohang,Yu, Mingxin,Wang, Meijun
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- The tertiary sulfonamide as a latent directed-metalation group: Ni 0-catalyzed reductive cleavage and cross-coupling reactions of aryl sulfonamides with Grignard reagents
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A mild method for the Ni0-catalyzed hydrodesulfamoylation (see scheme, B) of aryl sulfonamides (1→2) with iPr2Mg or iPrMgCl as β-hydride transfer sources can be linked with directed ortho metalation (A and C) to give meta-substituted aromatics 2. Cross-coupling process with alkyl and aryl Grignard reagents furnish disubstituted benzenes and bi- and teraryl compounds.
- Milburn, Robert R.,Snieckus, Victor
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p. 888 - 891
(2007/10/03)
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- One-step preparation of some 3-substituted anisoles
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A one-step preparation of 3-bromoanisole, 3-chloroanisole, and 3-trifluoromethylanisole from the corresponding 3-substituted nitrobenzenes is carried out by nucleophilic aromatic substitution of the nitro group with sodium or potassium methoxide, employing an effective amount of a phase-transfer catalyst (PTC), in a medium of a nonpolar aprotic solvent, under aerobic conditions, at a temperature of 50-65°C. The alkali methoxide used can be a pre-prepared solid, or it can be prepared in situ from the alkali hydroxide and methanol. The methoxydenitration proved to be very sensitive to the type of PTC. The effect of the solvent on the reaction is discussed. The targeted anisoles are obtained in yields of more than 80% and purities of greater than 99%.
- Zilberman, Joseph
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p. 303 - 305
(2013/09/06)
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- Electroreduction of Organic Compounds, 34 [1]. Cathodic Dehalogenation of Chloroarenes with Electron-Donating Substituents
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The electrochemical reduction of chlorinated arenes with electron-donating substituents, i.e. chlorotoluenes, -anisoles and -phenols, is studied. Preparative electrolyses are run in various solvent-supporting electrolytes under potentiostatic and galvanostatic conditions at lead or carbon cathodes. A partial and mostly regioselective hydrodechlorination of compounds with two or more chloro substituents is possible under suitable conditions. The replacement of one single chloro substituent, in particular in a para-position, is difficult. Highly toxic and persistent oligochloro derivatives are thus transformed into less problematic compounds with a low degree of chlorination. The chlorine content of real-life materials such as extracts of soil contaminated with chlorinated phenols and Nitrofen can also be significantly decreased by electroreduction.
- Kranz, Olaf,Voss, Jürgen
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p. 1187 - 1200
(2007/10/03)
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- Process for preparation of substituted aromatic compound
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A substituted aromatic compound substituted with Q is obtained by reacting a phosphazenium compound represented by formula (1) (in the formula, Q?represents an anion in a form derived by elimination of a proton from an inorganic acid, or an active hydrogen compound having an active hydrogen on an oxygen atom, a nitrogen atom or a sulfur atom; a, b, c and d, each independently, is 0 or 1, but all of them are not 0 simultaneously; and R groups represent the same or different hydrocarbon groups having 1 to 10 carbon atoms, or two Rs on each common nitrogen atom may be bonded together to form a ring structure) with a halogenated aromatic compound having halogen atoms; whereby, at least one halogen atom in the halogenated aromatic compound is substituted with Q (where, Q represents an inorganic group or an organic group in a form derived by elimination of one electron from Q?in formula (1)).
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- Halodediazoniations of dry arenediazonium o-benzenedisulfonimides in the presence or absence of an electron transfer catalyst. Easy general procedures to prepare aryl chlorides, bromides, and iodides
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The paper reports the results of a wide study aimed at preparing aryl chlorides 3 (19 examples), bromides 4 (19 examples), and iodides 5 (9 examples) by halodediazoniation of dry arenediazonium o-benzenedisulfonimides 1 with tetraalkylammonium halides 2. The reactions were carried out in anhydrous acetonitrile at room temperature (~20 °C) in the presence of copper powder and at 60 °C or room temperature without the catalyst. In optimal conditions the yields were from good to excellent (60 reactions, 61- 94% yield), with only a few exceptions (8 reactions, 51-55% yield). A good amount of the o-benzenedisulfonimide (7) was always recovered from the reactions and could then be reused to prepare salts 1. An interesting aspect of this research is the surprising role of the anion of o- benzenedisulfonimide (9) as an electron transfer agent.
- Barbero,Degani,Dughera,Fochi
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p. 3448 - 3453
(2007/10/03)
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- Benzopyridazinone and pyridopyridazinone compounds
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Benzo or pyridopyridazinones and pyridazinthiones of the formula STR1 wherein: X and Y are nitrogen or carbon, provided that at least one is carbon, and Z is oxygen or sulfur; R1 is hydrogen, lower alkyl, aryl, aralkyl, heterocyclo, heterocyclo lower-alkyl, heteroaryl, or heteroaralkyl; R2, R3, R4, R5 and R6 are independently selected from hydrogen, lower alkyl, halo, carboxy, alkoxycarbonyl, carbamoyl, lower-alkyl carbonyl, halocarbonyl, thiomethyl, trifluoromethyl, cyano or nitro; or a pharmaceutically acceptable ester, ether or salt thereof, have been found to be useful as an anti-inflammatory, antasthmatic, immunosuppressive, anti-allograft rejection, anti-graft-vs-host rejection, autoimmune disease or analgetic agent(s).
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- Evidence for Charge Localisation by Strong Hydrogen Bonding in Fluoride-Phenol Complexes and its Effects on Reactivity/Selectivity
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Measurements of yields and rates of methylation of substituted phenols, and correlations for the prediction of MeI labelling conditions, show evidence for charge localisation in fluoride-phenol strong hydrogen-bonded complexes and its effects on selectivity/reactivity.
- Cork, David G.,Hayashi, Nobuyoshi
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p. 527 - 529
(2007/10/02)
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- Correlation of Reaction Rates with a Substituent Constant Scale Derived from Calculated Electron Densities for a Computer Control Algorithm
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A new ? substituent scale based on electron density calculations by the AM1 quantum mechanical model has been established and used to correlate rates of O-methylation of substituted phenols, as part of a chemical artificial intelligence to control a fully automated apparatus for methyl iodide labeling.
- Cork, David G.,Hayashi, Nobuyoshi
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p. 1583 - 1585
(2007/10/02)
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- Silylative Decarbonylation: A New Route to Arylsilanes
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A new synthetic procedure for the preparation of aromatic chlorosilanes via the palladium-catalyzed reaction of methylchlorodisilanes and aromatic acid chloride is described.The silylative decarbonylation process is solventless, can utilize low metal catalyst loadings (500-1000 ppm Pd), is carried out under moderate conditions (145 deg C), and selectively gives aromatic chlorosilanes in good yield, generally 60-85percent.The procedure is tolerant of a variety of aromatic substituents, for example, alkyl, halo, nitro, cyano, imide, acid anhydride, etc., and the synthesis ofseveral new substituted aromatic chlorosilanes containing benzoyl chloride and phthalic anhydride moieties is described.Chloromethyldisilane starting reagents are available from the direct reaction of methyl chloride and silicon, making this methodology an attractive synthetic route to functionalized aromatic chlorosilanes.
- Rich, Jonathan D.
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p. 5886 - 5893
(2007/10/02)
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- Electrosynthesis of aryl-carboxylic acids from chlorobenzene derivatives and carbon dioxide
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The electrocarboxylation of a large variety of chlorobenzenic compounds is achieved in N,N-dimethylformamide by constant current electrolysis between a stainless steel cathode and a sacrificial magnesium anode in a diaphragmless cell. Substituted benzoic acids are obtained in high yield in simle conditions thus avoiding the usual preparation of organometallic intermediates.
- Heintz, Monique,Sock, Oumar,Saboureau, Christophe,Perichon, Jacques,Troupel, Michel
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p. 1631 - 1636
(2007/10/02)
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- Process for the selective production of dihydroxybenzenes
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The known nuclear hydroxylation of phenol or substituted phenols or phenol ethers with organic solutions of hydrogen peroxide in the presence of a catalyst is carried out in improved manner by employing both (1) a special, practically water free solution of hydrogen peroxide in an organic solvent which forms an azeotrope with water, which azeotrope boils below the boiling point of hydrogen peroxide, and (2) selenium dioxide as a catalyst. Through this, the nuclear hydroxylation is substantially simpler than previously. Besides, for the first time, it is possible to control the ortho to para ratio or the two ortho ratios to each other.
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- PHASE-TRANSFER NUCLEOPHILIC AROMATIC SUBSTITUTION OF Cr(CO)3-COMPLEXED DICHLOROBENZENES WITH ALCOHOLS
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Cr(CO)-complexed ortho- and para-dichlorobenzenes react with primary and secondary alcohols, in the presence of KOH, under phase-transfer conditions to give monosubstitution products only.The meta isomer affords disubstitution products also.The same reaction, carried out in DMSO with alcohols in excess, leads in all cases to dialkoxy derivatives.Factors potentially influencing the reactivity of Cr(CO)3-complexed ortho-, meta-, and para-dichlorobenzenes are discussed.
- Alemagna, Andreina,Baldoli, Clara,Del Buttero, Paola,Licandro, Emanuela,Maiorana, Stefano
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p. 555 - 560
(2007/10/02)
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- PHOTOLYSIS OF m.CHLOROANISOLE : NATURE OF EXCITED STATES
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The distribution of the photoproducts in the photolysis of m.chloroanisole is used as a probe for the identification of the exited states responsible for the reduction and substitution.
- Vermeulen, J.,Soumillon, J. PH.
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p. 1045 - 1054
(2007/10/02)
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- Process for substitution of aromatic organic compounds
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The invention relates to a process for substituting for a halogen atom attached to the nuclear carbon atom of an aromatic ring, a substituent of the formula -O-R wherein R represents alkyl, alkenyl, alkynyl or benzyl, which process comprises reacting the halogen-substituted aromatic compound with an alcoholate of the formula Mn+ [O--R]n? wherein M is an alkali metal atom or alkaline earth metal atom, n is the valency of M, and R is as defined above, in the presence of an active catalyst mixture comprising (i) a formic acid ester of an organic alcohol having the formula R2 --O--CO--H wherein R2 is as defined for R above; and (ii) a cuprous salt; in a liquid medium which is a solvent for the catalyst mixture and in which the halogen-substituted aromatic compound is at least partially soluble, under substantially anhydrous conditions and a non-oxidizing atmosphere. The invention further relates to a catalyst used in the above process.
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- THE REACTIONS OF UNACTIVATED ARYL HALIDES WITH SODIUM METHOXIDE IN HMPA; SYNTHESIS OF PHENOLS, ANISOLES, AND METHOXYPHENOLS
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Sodium methoxide reacts with dichlorobenzenes in HMPA to give the chloroanisoles as a result of a SNAr process.Excess MeONa then effects the demethylation of the ethers to give the chlorophenols via an SN2 reaction.With tri- and tetrachlorobenzenes the initially formed chloroanisoles can be dealkylated to chlorophenols or can suffer further substitution to give the chlorodimethoxybenzenes; these react with excess MeONa to give the chloromethoxyphenols.The results obtained with the various isomers of the di-, tri-, and tetrachlorobenzenes are presented and discussed on the basis of the electronic effects of the substituents.
- Testaferri, L.,Tiecco, M.,Tingoli, M.,Chianelli, D.,Montanucci, M.
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p. 193 - 198
(2007/10/02)
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