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Fabrication of La2O3/Bi2O3/silver orthophosphate Heterojunction Catalyst for the Visible Light Mediated Remediation of Refractory Pollutants
The development of silver orthophosphate based ternary composite catalyst for the augmented visible light assisted photocatalytic abatement of toxic refractory pollutants was accepted. It was confounded that the synthesized catalyst effectively degrade toxic organic dyes including methylene blue (MB), methyl orange (MO), rhodamine B (RhB) and acid red 18 (AR 18) with complete decolourisation and above 90 % mineralization. The hazardous pesticides such as 2, 4-dichlorophenoxyacetic acid (2,4-D), highly toxic insecticide acephate and the pharmaceutical antibiotic tetracycline were succesfully degraded. Here, it is the first time reporting La2O3/Bi2O3 doped silver orthophosphate ternary catalyst for the removal of toxic organic pollutants in a short time with excellent mineralization. The better reproducibility and accountable stability of the composite catalyst paved the way for making it a promising catalyst for future applications.
Abraham, Thomas,Priyanka, Ragam N.,Joseph, Subi,Chacko, Anu Rose,Mathew, Beena
(2021)
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Organophotochemical SNAr Reactions of Mildly Electron-Poor Fluoroarenes
C–F functionalization of arenes with a range of alcohol and pyrazole nucleophiles has been achieved without the need for metal catalysts or highly electron-poor substrates. Treatment of fluoroarenes with alcohols or pyrazoles and DDQ under irradiation by blue LED light provides the corresponding substituted products. The procedure is complementary to classical SNAr chemistry which generally requires basic reaction conditions and high temperatures, and provides products under non-basic conditions at ≈ 40 °C.
Burton, Jonathan W.,Genovino, Julien,Lian, Yajing,Monck, Nat,Sheridan, Thomas,Yayla, Hatice G.
supporting information
p. 2766 - 2770
(2020/05/18)

From Anilines to Aryl Ethers: A Facile, Efficient, and Versatile Synthetic Method Employing Mild Conditions
We have developed a simple and direct method for the synthesis of aryl ethers by reacting alcohols/phenols (ROH) with aryl ammonium salts (ArNMe3+), which are readily prepared from anilines (ArNR′2, R′=H or Me). This reaction proceeds smoothly and rapidly (within a few hours) at room temperature in the presence of a commercially available base, such as KOtBu or KHMDS, and has a broad substrate scope with respect to both ROH and ArNR′2. It is scalable and compatible with a wide range of functional groups.
Wang, Dong-Yu,Yang, Ze-Kun,Wang, Chao,Zhang, Ao,Uchiyama, Masanobu
supporting information
p. 3641 - 3645
(2018/03/13)

Cation Radical Accelerated Nucleophilic Aromatic Substitution via Organic Photoredox Catalysis
Nucleophilic aromatic substitution (SNAr) is a direct method for arene functionalization; however, it can be hampered by low reactivity of arene substrates and their availability. Herein we describe a cation radical-accelerated nucleophilic aromatic substitution using methoxy- and benzyloxy-groups as nucleofuges. In particular, lignin-derived aromatics containing guaiacol and veratrole motifs were competent substrates for functionalization. We also demonstrate an example of site-selective substitutive oxygenation with trifluoroethanol to afford the desired trifluoromethylaryl ether.
Tay, Nicholas E. S.,Nicewicz, David A.
supporting information
p. 16100 - 16104
(2017/11/22)

Selective water-based oxychlorination of phenol with hydrogen peroxide catalyzed by manganous sulfate
An efficient method for the selective oxychlorination of phenol to 2,4-dichlorophenol catalyzed by manganous(ii) sulfate is developed using hydrogen chloride as a chlorinating source, hydrogen peroxide as an oxidant and water as a solvent. The catalyst has high activity and selectivity under mild conditions. The products are automatically isolated from aqueous solution, which also contains the catalyst at the end of the reaction, and hence product separation and catalyst recycling are both simple in this system. The performance of manganous(ii) sulfate with the oxidative chlorinating system HCl/H2O2 indicates that this is a promising synthetic method for the manufacture of various 2,4-dichlorophenol derivatives.
Xin, Hongchuan,Yang, Shilei,An, Baigang,An, Zengjian
p. 13467 - 13472
(2017/03/11)

Benzene C-H Etherification via Photocatalytic Hydrogen-Evolution Cross-Coupling Reaction
Aryl ethers can be constructed from the direct coupling between the benzene C-H bond and the alcohol O-H bond with the evolution of hydrogen via the synergistic merger of photocatalysis and cobalt catalysis. Utilizing the dual catalyst system consisting of 3-cyano-1-methylquinolinum photocatalyst and cobaloxime, intermolecular etherification of arenes with various alcohols and intramolecular alkoxylation of 3-phenylpropanols with formation of chromanes are accomplished. These reactions proceed at remarkably mild conditions, and the sole byproduct is equivalent hydrogen gas.
Zheng, Yi-Wen,Ye, Pan,Chen, Bin,Meng, Qing-Yuan,Feng, Ke,Wang, Wenguang,Wu, Li-Zhu,Tung, Chen-Ho
supporting information
p. 2206 - 2209
(2017/05/12)

Room temperature C(sp2)-H oxidative chlorination: Via photoredox catalysis
Photoredox catalysis has been developed to achieve oxidative C-H chlorination of aromatic compounds using NaCl as the chlorine source and Na2S2O8 as the oxidant. The reactions occur at room temperature and exhibit exclusive selectivity for C(sp2)-H bonds over C(sp3)-H bonds. The method has been used for the chlorination of a diverse set of substrates, including the expedited synthesis of key intermediates to bioactive compounds and a drug.
Zhang, Lei,Hu, Xile
p. 7009 - 7013
(2017/10/05)

Sono-bromination of aromatic compounds based on the ultrasonic advanced oxidation processes
A novel, mild "sono-halogenation" of various aromatic compounds with potassium halide was investigated under ultrasound in a biphasic carbon tetrachloride/water medium. The feasibility study was first undertaken with the potassium bromide and then extended to chloride and iodide analogues. This methodology could be considered as a new expansion of the ultrasonic advanced oxidation processes (UAOPs) into a synthetic aspect as the developed methodology is linked to the sonolytic disappearance of carbon tetrachloride. Advantages of the present method are not only that the manipulation of the bromination is simple and green, but also that the halogenating agents used are readily available, inexpensive, and easy-handling.
Fujita, Mitsue,Lévêque, Jean-Marc,Komatsu, Naoki,Kimura, Takahide
p. 247 - 251
(2015/06/08)

SELECTIVE HYDROLYSIS AND ALCOHOLYSIS OF CHLORINATED BENZENES
The present invention relates to a process for providing a compound of formula (I):, wherein R is hydrogen or R', wherein R' is –(C1-C4)alkyl, and Hal is a halogen, the process comprising the step of: reacting a compound of formula (II) wherein Hal is defined as above, with an alkali metal alkoxide of the formula XOR', wherein X is an alkali metal, and R' is defined as above.
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(2015/04/22)

PROCESS FOR HYDROLYZING 1,2,4-TRIHALOBENZENE
The present invention relates to a process for providing a compound of formula (I): wherein Hal is a halogen, the process comprising the step of: reacting a compound of formula (II) wherein Hal is defined as above, with an alkali metal sulfite of the formula X2SO3 and an alkali metal hydroxide of the formula YOH, wherein X and Y are independently selected from an alkali metal.
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(2015/04/22)

Practical and metal-free electrophilic aromatic halogenation by interhalogen compounds generated in situ from N-halosuccinimide and catalytic TMSCL
Halomonochloride compounds (ClCl, BrCl, ICl) generated in situ from N-halosuccinimide and catalytic chlorotrimethylsilane (TMSCl, 0.1 equiv) can efficiently halogenate aromatic compounds to give halogenated products in good to excellent yields and selectivities. The reaction can be carried out at room temperature or at lower temperatures, requires only one hour, is practical to apply to a wide range of substrates, and provides a simple access to a variety of haloarene compounds. Georg Thieme Verlag Stuttgart New York.
Maibunkaew, Tapanee,Thongsornkleeb, Charnsak,Tummatorn, Jumreang,Bunrit, Anon,Ruchirawat, Somsak
supporting information
p. 1769 - 1775
(2014/08/05)

Metal and H2O2 free aerobic oxidative aromatic halogenation with [RNH3+] [NO3-]/HX and [BMIM(SO3H)][NO3)x(X)y] (X = Br, Cl) as multifunctional ionic liquids
Novel multifunctional ionic liquids (ILs) are generated by addition of HBr or HCl to alkylammonium nitrates ([RNH3+] [NO 3-]) and to 3-methyl-1-(butyl-4-sulfonyl)imidazolium nitrate ([BMIM(SO3H)][NO3]). The resulting [RNH 3+] [NO3-]/HX and mono (3-methyl-1-(butyl-4-sulfonyl)imidazolium) monohalogenide mononitrate ([BMIM(SO3H)][NO3)x(X)y] (X = Br, Cl)) systems act as solvent and promoter for aerobic oxidative halogenation of arenes under mild conditions in high yields that can be repeated over several cycles.
Prebil, Rok,Laali, Kenneth K.,Stavber, Stojan
supporting information
p. 2108 - 2111
(2013/06/05)

Mechanistic insight into halide oxidation by non-heme iron complexes. Haloperoxidase versus halogenase activity
This work presents the first detailed study on mechanistic aspects of halide oxidation by non-heme iron complexes. We show that while iron(iii)-hydroperoxo complexes oxidise halides via oxygen atom transfer, the corresponding iron(iv)-oxo complex reacts via electron transfer. This journal is The Royal Society of Chemistry 2013.
Vardhaman, Anil Kumar,Barman, Prasenjit,Kumar, Suresh,Sastri, Chivukula V.,Kumar, Devesh,De Visser, Sam P.
p. 10926 - 10928
(2013/11/19)

Bronsted acidic ionic liquid accelerated halogenation of organic compounds with N-halosuccinimides (NXS)
The Bronsted-Acidic ionic liquid 1-methyl-3-(4-sulfobutyl) imidazolium triflate [BMIM(SO3H)][OTf] was demonstrated to act efficiently as solvent and catalyst for the halogenation of activated organic compounds with N-halosuccinimides (NXS) under mild conditions with short reaction times. Methyl aryl ketones were converted into a-halo and a,a-dihaloketones, depending on the quantity of NXS used. Ketones with activated aromatic rings were selectively halogenated, however in some cases mixtures of a-halogenated ketone and ring-halogenated ketones were obtained. Activated aromatics were regioselectively ring halogenated to give mono- and dihalo-substituted products. The [BMIM(SO3H)][OTf] ionic liquid (IL-A) was successfully reused eight times in a representative monohalogenation reaction with no noticeable decrease in efficiency. An effective halogenation scale-up in this IL is also presented. The reactivity trend and the observed chemo- and regioselectiivities point to an ET process in these IL-promoted halofunctionalization reactions.
Vrazic, Dejan,Jereb, Marjan,Laali, Kenneth K.,Stavber, Stojan
p. 74 - 96
(2013/04/10)

Trichloroisocyanuric acid in 98% sulfuric acid: A superelectrophilic medium for chlorination of deactivated arenes
Trichloroisocyanuric acid (TCCA) reacts with arenes and its reactivity is highly affected by the acid strength of the reaction medium. Deactivated arenes are efficiently chlorinated by TCCA in H2SO4. Our results, along with DFT calculations and 13C NMR spectrometry suggest the formation of a monoprotonated TCCA superelectrophile as the reactive species that can efficiently transfer electrophilic Cl+ to even very weak nucleophiles, such as m-dinitrobenzene.
Mendo?a, Gabriela Fonseca,Senra, M?nica Rufino,Esteves, Pierre M.,De Mattos, Marcio C.S.
experimental part
p. 176 - 181
(2012/04/04)

The use of sodium chlorate/hydrochloric acid mixtures as a novel and selective chlorination agent
Sodium chlorate/hydrochloric acid mixtures were used to chlorinate activated arenes and the α-position of ketones. This chlorination method was used to produce selectively mono-, di-, and trichlorinated compounds by controlling the molarity of sodium chlorate. This reagent proved to be much more efficient and easier to handle than chlorine gas.
Moon, Byung Seok,Choi, Han Young,Koh, Hun Yeong,Chi, Dae Yoon
experimental part
p. 472 - 476
(2011/12/04)

Hypochlorite-induced ipso-substitution reactions of aromatic alcohols and related compounds
Organic solvent extracts derived from aqueous hypochlorite/phase-transfer catalyst solutions induce rapid and efficient ipso substitution of aromatic carbinols and related substrates. The key parameter impacting rates and yields is pH of the original hypochlorite/phase-transfer catalyst component. Georg Thieme Verlag Stuttgart - New York.
Carrillo, Hector V.,Rodriguez, Angelica Y.,Landolt, Robert G.,Hendrickson, William H.
experimental part
p. 2069 - 2071
(2011/10/09)

Phosphonium nitrate ionic liquid catalysed electrophilic aromatic oxychlorination
Trioctylmethylphosphonium nitrate (P8,8,8,1NO3), an ionic liquid made via a green synthesis, catalyses electrophilic aromatic chlorination of arenes with HCl and air at 80 °C. The aromatic oxychlorination is truly catalytic in nitrate, proceeds without added solvents, and uses atmospheric oxygen as oxidant. The extent of chlorination can be controlled to yield selectively mono or dichlorinated products, and the ionic liquid catalyst can be recycled. Dependence of the chlorination rate on HCl and nitrate concentrations as well as on the rate of re-oxidation of the nitrogen intermediates by air, allowed us to propose a reaction mechanism.
Noe, Marco,Perosa, Alvise,Selva, Maurizio,Zambelli, Luca
experimental part
p. 1654 - 1660
(2010/12/19)

Microwave-assisted methylation of phenols with tetramethylammonium chloride in the presence of K2CO3 or Cs2CO3
We have evaluated the potential of using tetramethylammonium chloride (Me4NCl) as an alternative methylating agent for phenols under microwave-assisted conditions. Its chemical behavior was tested in a reaction with 2-naphthol in the presence of various bases and solvents. The method was then applied in 1,2-dimethoxyethane or toluene under heterogeneous conditions for the O-methylation of a series of phenolic compounds. We found that many simple phenols can be methylated in the presence of K2CO3, whereas some other less-reactive phenols require the presence of the more reactive Cs2CO3.
Mara?, Nenad,Polanc, Slovenko,Ko?evar, Marijan
experimental part
p. 11618 - 11624
(2009/04/05)

A simple, efficient and regioselective oxychlorination of aromatic compounds using ammonium chloride and oxone
A simple, efficient, mild and regioselective method for oxychlorination of aromatic compounds is reported. The electrophilic substitution of chlorine generated in situ from NH4Cl as a chlorine source and oxone as an oxidant is reported for the first time.
Narender,Mohan, K.V.V. Krishna,Srinivasu,Kulkarni,Raghavan
p. 1335 - 1338
(2007/10/03)

Highly efficient, para-selective oxychlorination of aromatic compounds using potassium chloride and Oxone
A highly efficient, regioselective method for oxychlorination of aromatic compounds is possible through electrophilic substitution of chlorine generated in situ from KCl as a chlorine source and Oxone as an oxidant for the first time.
Narender,Srinivasu,Kulkarni,Raghavan
p. 279 - 286
(2007/10/03)

Selective halogenation of aromatics by dimethyldioxirane and halogen ions
The oxidation of halogen anions by dimethyldioxirane (DMD) produced reactive species which led, in acidic media, to the halogenation of activated aromatic rings. The reaction can be efficiently controlled to obtain selective and mixed halogenated species.
Bovicelli,Mincione,Antonioletti,Bernini,Colombari
p. 2955 - 2963
(2007/10/03)

A simple and practical halogenation of activated arenes using potassium halide and oxone in water-acetonitrile medium
A simple and practical halogenation of activated arenes using a reagent combination of potassium halide and oxone in water-acetonitrile medium is presented. The halogenated products were obtained with good yields and in high purity.
Tamhankar,Desai,Mane,Wadgaonkar,Bedekar
p. 2021 - 2027
(2007/10/03)

Process for generating electrophiles from anions by reaction with electrophilic fluorinating agent
A process includes substituting a substituent on a substrate. The process includes reacting a salt of an anionic form of the substituent with an electrophilic fluorination agent to provide an electrophile containing a cationic form of the substituent. The electrophile is then electrophilically substituted on the substrate. In some aspects of the process, the substrate can be an aromatic or a non-aromatic. The process can be used for a variety of reactions having electrophilic mechanisms, including halogenation, thiocyanation and nitration.
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(2008/06/13)

Generation of interhalogen fluorides under mild conditions: A comparison of sluggish and reactive interhalogen fluorides
Interhalogen fluorides (XF; X = I, Br, or Cl) generated from xenon difluoride (XeF2) or triethylamine trihydrofluoride (TREAT HF) with iodine (I2), N-halosuccinimides (NXS; X = I, Br, or Cl), or alkylhypohalites (ROX; R = CH3 or t-Bu, X = Br or Cl) with alkenes and aromatics are reported. A comparison of the above reactions with other methods reported in the literature to generate interhalogen fluorides is made. Interhalogens generated from direct action of elemental fluorine (F2) or XF3 (X = I, Br, or Cl) with chlorine (Cl2), bromine (Br2), or iodine (I2) give a species that can react with electron-deficient alkenes or aromatics. These reagents are too reactive for electron-rich substrates. Interhalogen fluorides from reagents like NXS or ROX with XeF2 or amine HF are much less reactive and give good yields with electron-rich akenes or aromatics.
Shellhamer, Dale F.,Horney, Mark J.,Pettus, Benjamin J.,Pettus, Tobiah L.,Stringer, Joy Merry,Heasley, Victor L.,Syvret, Robert G.,Dobrolsky Jr., John M.
p. 1094 - 1098
(2007/10/03)

Chlorination of aromatic compounds with chlorous acid under non-aqueous conditions
The non-aqueous solution of chlorous acid is a versatile chlorinating agent for aromatic compounds, e.g. alkylbenzenes, anisoles, and acetanililides. It is also an effective chlorine-substitute for the conversion of aryl bromides into aryl chlorides under mild conditions. The stoichiometry of the chlorination reaction is ArH+3HOClO→ArCl+2ClO2+2H2O, and the mode of dissociation of chlorous acid in dichloromethanc is 3HOClO→HOCl+2ClO2+H2O.
Muathen, Hussni A.
p. 1493 - 1497
(2007/10/03)

Simple and practical halogenation of arenes, alkenes and alkynes with hydrohalic acid/H2O2 or TBHP)
A simple protocol for the halogenation of arenes utilizing a combination of aqueous hydrogen peroxide (34 %) or tert-butylhydroperoxide (70 %) and hydrohalic acid is presented. A similar procure of oxyhalogenation involving the in situ generation of positive halogen reagents is applied for the preparation of vicinal trans-dibromoalkanes and dichloroalkanes from alkenes. The reaction of alkenes with a combination of hydrochloric acid and hydrobromic acid with hydrogen peroxide gave a mixture of 1-bromo 2-chloro alkanes and 1,2-dibromoalkanes: Oxidative bromination of alkynes is also reported under similar conditions.
Barhate, Nivrutti B.,Gajare, Anil S.,Wakharkar, Radhika D.,Bedekar, Ashutosh V.
p. 11127 - 11142
(2007/10/03)

Simple and efficient chlorination and bromination of aromatic compounds with aqueous TBHP (or H2O2) and a hydrohalic acid
A combination of aqueous tert-butylhydroperoxide (70%) or hydrogen peroxide (34%) and a hydrohalic acid was found effective in chlorination and bromination of aromatic compounds.
Barhate, Nivrutti B.,Gajare, Anil S.,Wakharkar, Radhika D.,Bedekar, Ashutosh V.
p. 6349 - 6350
(2007/10/03)

Acid-catalyzed hydrolysis of some primary alkyl phenyl ethers
Products were analyzed and rate constants of disappearance and hydrolysis, alkylation and/or rearrangement were measured for methyl, ethyl, propyl and allyl phenyl ethers by GC in concentrated aqueous perchloric acid solutions. Chlorination of the substrate and possibly of the product, phenol, was observed beside the hydrolysis of methyl phenyl ether and a slight chlorination of phenol beside the hydrolysis of ethyl phenyl ether. A marked Claisen rearrangement to isopropylphenols and alkylation to propyl isopropylphenyl ethers were observed in addition to the hydrolysis of propyl phenyl ether. The Claisen rearrangement to o-allylphenol was estimated to be quantitative in the case of allyl phenyl ether. The change of the reaction mechanism from A-2 (MeOPh and EtOPh) possibly via A-2(carbocation)(PrOPh?) to A-1 (allyl phenyl ether and possibly PrOPh) was deduced from the products, reaction rates, activation parameters, solvent deuterium isotope effect and parameters of excess acidity plots. Acta Chemica Scandinavica 1997.
Lajunen, Martti,Laine, Riitta,Aaltonen, Marika
p. 1155 - 1161
(2007/10/03)

Mild chlorination of aromatic compounds with tin(IV) chloride and lead tetraacetate
SnCl4/Pb(OAc)4 acts as a safe source of Cl2 for the chlorination of aromatic compounds. A variety of aromatic compounds are effectively chlorinated with SnCl4/Pb(OAc)4 under mild conditions. The mixture is a selective chlorinating agent, particularly with polyalkylbenzenes, polycyclic aromatic compounds and anisoles.
Muathen, Hussni A.
p. 8863 - 8866
(2007/10/03)

Correlation of Reaction Rates with a Substituent Constant Scale Derived from Calculated Electron Densities for a Computer Control Algorithm
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
p. 1583 - 1585
(2007/10/02)

Synthesis of 2,6-disubstituted and 2,3,6-trisubstituted anilines
A number of 2,6-disubstituted and 2,3,6-trisubstituted anilines have been prepared via the selective para dehalogenation of the corresponding anilines. Modification of the substituents on the amino nitrogen demonstrates that the selectivity is derived from steric rather than electronic effects. The effects of the choice of formate hydrogen donor, Pd catalyst, solvent, and temperature upon the efficiency and selectivity of the dehalogenation are discussed.
Pews,Hunter,Wehrmeyer
p. 4809 - 4820
(2007/10/02)

Electroreductive Dehalogenation of Chlorinated Aromatic Ethers. Unexpected Electrogenerated Base Catalyzed Reactions
The electroreductive dehalogenation of several mono- and polychlorinated aromatic ethers that serve as models of dioxins has been studied.The dechlorination was achieved by a simple constant-current electrolysis using a lead cathode in dimethylformamide.It was shown that 2,4,6-trichloroanisole undergoes successive dechlorination and the chlorine in the 2-position is selectively eliminated.Competitive reactions and cyclic voltammetric measurements suggested the increasing reactivity order of mono- di- trichloride for the reductive dechlorination.Use of allyl 2-chloro phenyl ether as a probe for radical cyclization indicated that free radical intermediates are of little importance.Thus, incipient radicals are immediately reduced to anionic intermediates.The electrolyses in the presence of deuterium oxide revealed proton sources for the present dechlorination.In these attempts, novel phenomena due to electrogenerated base (EGB) were found: di- and trichlorides underwent an unexpected overincorporation of deuterium in their dechlorinated products; a selective formation of Z-enol ethers from the allylic ethers was encountered.The mechanistic features of the present electroreductive dechlorination are discussed.
Kimura, Makoto,Miyahara, Hiroyoshi,Moritani, Noriyuki,Sawaki, Yasuhiko
p. 3897 - 3902
(2007/10/02)

Facile Synthesis of Chloro-substituted Aromatic Ethers by Use of Benzyltrimethylammonium Tetrachloroiodate
The reaction of aromatic ethers with a calculated amount of benzyltrimethylammonium tetrachloroiodate in acetic acid (or dichloromethane) under mild conditions gave, selectively, the objective chloro-substituted aromatic ethers in good yields.
Kajigaeshi, Shoji,Shinmasu, Youichi,Fujisaki, Shizuo,Kakinami, Takaaki
p. 415 - 418
(2007/10/02)

Highly Selective Aromatic Chlorination. Part 3. Kinetics and Mechanism of Chlorination of Electron-rich Aromatic Compounds by N-Chloroamines in Acidic Solution
The highly selective chlorination of electron-rich aromatic compounds with N-chloroamines in trifluoroacetic acid (TFA) is first order in both the aromatic substrate and the chlorinating agent.Kinetic and competitive kinetic studies show that electron-donating substituents on the substrate and electron-withdrawing substituents on the N-chloroamine have a marked rate-enhancing effect.Two mechanisms that fit the experimentally observed kinetics and that account for the high selectivity for 4-chlorination in terms of an electronic effect are proposed, namely an arenium-ion mechanism and an electron-transfer chain reaction.Evidence from chemical trapping experiments and from other studies suggest that for the majority of the substrates the chlorination proceeds by the arenium ion mechanism.However, for substrates, such as 1,4-dimethoxybenzene, that are very susceptible to one-electron oxidation chlorination may proceed at least in part by the electron-transfer chain reaction.
Smith, John R. Lindsay,McKeer, Linda C.,Taylor, Jonathan M.
p. 1529 - 1536
(2007/10/02)

Highly Selective Aromatic Chlorinations. Part 2. The Chlorination of Substituted Phenols, Anisoles, Anilines, and Related Compounds with N-Chloroamines in Acidic Solution
Phenols, anisoles, anilines, and related compounds are chlorinated in trifluoroacetic acid at room temperature by N-chlorodialkylamines and N-chlorotrialkylammonium salts.With monsubstituted compounds and their 2- and 3-substituted derivatives the reaction occurs efficiently and selectively at the 4-position.The reactivity of these substrates and the selectivity of their chlorinations are determined by electronic rather than steric effects of the substituent.Blocking the reaction with a substituent at the 4-position generally leads to only poor or moderate yields of the 2-chlorinated product.Evidence for radical and cation radical intermediates has been obtained in the reactions of some of the 4-substituted reactants and the mechanism of chlorination is discussed in the light of these findings.The reactions of selected substrates have been scaled up to give laboratory syntheses.
Smith, John R. Lindsay,McKeer, Linda C.,Taylor, Jonathan M.
p. 385 - 392
(2007/10/02)

PHENYLATION CATIONIQUE DU CHLORO-4 ANISOLE, ETUDE DE LA MIGRATION DU CHLORE ET DU PHENYLE DANS LES CATIONS IPSO-ARENIUM.
The phenyl cations obtained from the thermolysis of benzenediazonium tetrafluoroborate react with 4-chlroanisole to give, in addition to phenylation products at position 2 and 3, 2-chloro-4-methoxybiphenyl.The latter is formed by the attack of C6H5(1+) ipso to the chlorine followed by 1,2 migration of the halogen.This rearrangement is totally suppressed in nucleophilic solvents such as dimethylsulfoxide, whereas it is important in heterogeneous conditions.The ability of DMSO to trap the ipso-arenium ions has provided indirect evidence for the attack of C6H5(1+) ipso to the methoxy group. 1-2 migration of the phenyl group has been observed in arenium ions formed by attack of C6H5(1+) ipso to the chlorine and ipso to the methoxy group. 4-methoxybiphenyl and 2,4-dichloroanisole have not been detected by G L C so that dechlorophenylation of 4-chloroanisole must be negligible.
Pilski, J.,Court, J.,Eustathopoulos, H.,Bonnier, J. M.
p. 4331 - 4338
(2007/10/02)

THE SALT-FREE SYNTHESIS OF ARYL ETHERS USING METHYL TRICHLOROACETATE
Metyl trichloroacetate is an effective reagent for salt-free synthesis of aryl ethers and anisoles from phenols.
Renga, James M.,Wang, Pen-Chung
p. 69 - 76
(2007/10/02)

MECHANISMS OF EPOXIDATIONS AND CHLORINATIONS OF HYDROCARBONS BY INORGANIC HYPOCHLORITE IN THE PRESENCE OF A PHASE-TRANSFER CATALYST.
Inorganic hypochlorite in the presence of a quarternary ammonium salt (phase-transfer catalyst) not only epoxidizes several arenes to arene oxides in high yields but also converts toluene to alpha -chlorotoluene, anisole to ring chlorinated anisoles, and alkenes to a complex mixture of chlorinated and oxidized products, including the epoxide. More detailed studies with this system indicate the following: (1) the high-yield conversion of toluenes to benzyl chlorides proceeds with a deuterium isotope effect of 3. 6 and a rho ** plus value of minus 1. 7: (2) p-chloroanisole is the major product from anisole and is formed in a 22-fold greater quantity than o-chloroanisole; (3) the epoxidation of cis- and trans-alkenes is stereoselective but not completely stereospecific; (4) the chlorination of saturated hydrocarbons occurs with a selectivity that is experimentally identical with that of chlorine monoxide.
Fonouni,Krishnan,Kuhn,Hamilton
p. 7672 - 7676
(2007/10/02)

HIGH SITE-SELECTIVITY IN THE CHLORINATION OF ELECTRON-RICH AROMATIC COMPOUNDS BY N-CHLORAMMONIUM SALTS.
N-Chlorammonium salts are efficient and very site-selective monochlorinating agents for electron-rich aromatic compounds.
Smith, John R. Lindsay,McKeer, Linda C.
p. 3117 - 3120
(2007/10/02)

Formation of Nonaromatic Products in the Chlorination of Simple Substituted Aromatic Ethers
The neat chlorination of 4-chloroanisole produces 1,3,4,5,6-pentachloro-4-methoxycyclohexene in 35percent yield.Mono- and dichlorinated anisoles and a variety of simple substituted anisoles were chlorinated to determine the generality of nonaromatic product formation. 3,4-Dichloroanisole, 4-fluoroanisole, 4-bromoanisole, 4-methylanisole, and 4-chlorophenetole form similar products based on their spectral properties.These products are proposed to form by a cis-1,2-chlorine addition followed by rapid cis-1,4 chlorine addition.On the basis of the NMR data, a predominate configuration is proposed.
Watson, William David
p. 5270 - 5276
(2007/10/02)

PHOTOLYTIC α-ELIMINATION OF ORGANIC HALIDES FROM ORGANOTELLURIUM (IV) HALIDES
Irradiation of organotellurium(IV) halides in benzene affords the corresponding organic halide by α-elimination, the carbon-halogen bond being formed at ipso-position and in some case retentively.The reaction is not affected by the presence or absence of oxygen and t-butoxy radical.
Uemura, Sakae,Fukuzawa, Shin-ichi
p. 943 - 946
(2007/10/02)