Xn:Harmful;
106-43-4Relevant articles and documents
Zeolite-catalyzed chlorination of toluene by sulfuryl chloride: Activity, selectivity, and deactivation of ZSM-5
Chang, Chen-Chang,Burger, Mathew J.,Faitar, Gheorghita M.,Lund, Carl R. F.
, p. 59 - 67 (2001)
The chlorination of toluene by sulfuryl chloride was studied using ZSM-5 as the catalyst. A simple rate expression was developed that provides a reasonable quantitative description of the dependence of the initial rate of reaction upon temperature and reactant ratio. The selectivity did not vary significantly as temperature and reactant ratio changed. The effects of framework silica-alumina ratio and exchange cation were also examined. Changing the exchange cation had essentially no effect upon selectivity, but the catalytic activity was higher when K+ was used as the exchange cation compared to Na+ or H+. Varying the silica-alumina ratio of the zeolite had a very minor effect upon the activity, but the para-chlorotoluene/ortho-chlorotoluene product ratio increased from 1-1.5 to greater than 2.5 at the highest silica-alumina ratio. In all cases, the catalyst deactivated rapidly, but an oxidative treatment at elevated temperature fully restored the catalytic activity.
Vapor-Phase Isomerization of o-Chlorotoluene over H-Mordenite Treated with CF3Cl
Okazaki, Susumu,Jouhouji, Hirofumi
, p. 1931 - 1936 (1986)
Vapor-phase isomerization of o-chlorotoluene was somewhat promoted by H-mordenite (HM).The catalytic activity was appreciably enhanced by treatment with CF3Cl and other chlorofluorocarbons such as CF2ClCF2Cl and CF2ClCF3.In particular, maintenance of the HM catalyst activity was remarkably improved by CF3Cl treatment.The CF3Cl-treated HM also promoted vapor phase isomerization of p- and m-chlorotoluene.The catalytic activity was relatively long-lasting for the isomerization of p-chlorotoluene.Enlargement of the HM pore size on treatment with CF3Cl and other chlorofluorocarbons may contribute to increasing the catalytic activity and then maintaing it.
Glycinatocopper(II) complex as an efficient heterogeneous catalyst for aromatic Finkelstein reaction of aryl and heteroaryl bromides to chlorides
Verma, Sanny,Saran, Sandeep,Jain, Suman L.
, p. 178 - 183 (2014)
Glycinatocopper(II) complex 1, readily synthesized from copper chloride and glycine was characterized by various techniques including FTIR, XRD, TGA and SEM analysis. The as-synthesized copper complex was found to be a simple and efficient catalyst for the synthesis of aryl and heteroaryl chlorides via aromatic Finkelstein reaction of aryl and heteroaryl bromides in high to excellent yields. The developed glycinatocopper(II) catalyst could easily be recovered from the reaction mixture and reused successfully for several runs without any loss in catalytic efficiency. The developed methodology represents the first example of the use of heterogeneous catalyst for the synthesis of aryl and heteroaryl chlorides via aromatic Finkelstein reaction.
The base-induced fragmentation of N,N-dibenzyl-N'-aryltriazenes
Lormann, Matthias E. P.,Dahmen, Stefan,Avemaria, Frank,Lauterwasser, Frank,Bra?se, Stefan
, p. 915 - 918 (2002)
Deprotonation of N,N-dibenzyl-N'-aryltriazenes, either in liquid phase or on solid support, by a strong base (n-BuLi or LDA) leads to fragmentation of the N-N single bond to give an imine and a diazenyl anion, which decomposes by loss of nitrogen to the parent aryl anion. The imine is deprotonated to give a 2-aza allyl anion, which is subsequently trapped by electrophiles. As an overall result, this fragmentation of the T1 triazene anchoring group represents a new traceless cleavage mode of this linker. The same mode of fragmentation was observed for the T2 linker leading to 2-aza allyl anions in liquid phase. The dibenzylamino moiety is apparently crucial since pyrrolidinodiazenylarenes can be metallated at the heterocycle without cleavage.
Chlorination of aromatics with trichloroisocyanuric acid (TCICA) in bronsted-acidic imidazolium ionic liquid [BMIM(SO3H)][OTf]: An economical, green protocol for the synthesis of chloroarenes
Hubbard, Abigail,Okazaki, Takao,Laali, Kenneth K.
, p. 923 - 927 (2007)
A survey study on electrophilic chlorination of aromatics with trichloroisocyanuric acid (TCICA) in Bronsted-acidic imidazolium ionic liquid [BMIM(SO3H)][OTf] is reported. The reactions are performed under very mild conditions (at ～50°C) and give good to excellent yields, depending on the substrates. Chemoselectivity for mono- v. dichlorination can be tuned by changing the arene-to-TCICA ratio and the reaction time. The survey study and competitive experiments suggest that triprotonated/protosolvated TCICA is a selective/moderately reactive transfer-chlorination electrophile. Density functional theory was used as guide to obtain further insight into the nature of the chlorination electrophile and the transfer-chlorination step. CSIRO 2007.
Kinetic and Mechanisms of the Homogeneous, Unimolecular Elimination of Phenyl Chloroformate and p-Tolyl Chloroformate in the Gas Phase
Lezama, Jesus,Chuchani, Gabriel
, p. 664 - 670 (2015)
The gas-phase elimination of phenyl chloroformate gives chlorobenzene, 2-chlorophenol, CO2, and CO, whereasp-tolyl chloroformate produces p-chlorotoluene and 2-chloro-4-methylphenol CO2 and CO. The kinetic determination of phenyl chloroformate (440-480oC, 60-110 Torr) and p-tolyl chloroformate (430-480°C, 60-137 Torr) carried out in a deactivated static vessel, with the free radical inhibitor toluene always present, is homogeneous, unimolecular and follows a first-order rate law. The rate coefficient is expressed by the following Arrhenius equations: Phenyl chloroformate: Formation of chlorobenzene, log kI = (14.85 ± 0.38) - (260.4 ± 5.4) kJ mol-1 (2.303RT)-1; r = 0.9993 Formation of 2-chlorophenol, log kII = (12.76 ± 0.40) - (237.4 ± 5.6) kJ mol-1(2.303RT)-1; r = 0.9993 p-Tolyl chloroformate: Formation of p-chlorotoluene: log kI = (14.35 ± 0.28) - (252.0 ± 1.5) kJ mol-1 (2.303RT)-1; r = 0.9993 Formation of 2-chloro-4-methylphenol, log kII = (12.81 ± 0.16) - (222.2 ± 0.9) kJ mol-1(2.303RT)-1; r = 0.9995 The estimation of the kI values, which is the decarboxylation process in both substrates, suggests a mechanism involving an intramolecular nucleophilic displacement of the chlorine atom through a semipolar, concerted four-membered cyclic transition state structure; whereas the kII values, the decarbonylation in both substrates, imply an unusual migration of the chlorine atom to the aromatic ring through a semipolar, concerted five-membered cyclic transition state type of mechanism. The bond polarization of the C-Cl, in the sense Cδ+Clδ-, appears to be the rate-determining step of these elimination reactions.
O,N,N-Pincer ligand effects on oxidatively induced carbon-chlorine coupling reactions at palladium
Wright, Luka A.,Hope, Eric G.,Solan, Gregory A.,Cross, Warren B.,Singh, Kuldip
, p. 6040 - 6051 (2015)
The syntheses of two families of sterically tuneable O,N,N pro-ligands are reported, namely the 2-(phenyl-2′-ol)-6-imine-pyridines, 2-(C6H4-2′-OH),6-(CMeNAr)C5H3N [Ar = 4-i-PrC6H4 (HL1a), 2,6-i-Pr2C6H3 (HL1b)] and the 2-(phenyl-2′-ol)-6-(amino-prop-2-yl)pyridines, 2-(C6H4-2′-OH),6-(CMe2NHAr)C5H3N [Ar = 4-i-PrC6H4 (HL2a), 2,6-i-Pr2C6H3 (HL2b)], using straightforward synthetic approaches and in reasonable overall yields. Interaction of HL1a/c and HL2a/b with palladium(ii) acetate affords the O,N,N-pincer complexes, [{2-(C6H4-2′-O)-6-(CMeNAr)C5H3N}Pd(OAc)] (Ar = 4-i-PrC6H4 (1a), 2,6-i-Pr2C6H3 (1b)) and [{2-(C6H4-2′-O)-6-(CMe2NHAr)C5H3N}Pd(OAc)] (Ar = 4-i-PrC6H4 (2a), 2,6-i-Pr2C6H3 (2b)), which can be readily converted to their chloride derivatives, [{2-(C6H4-2′-O)-6-(CMeNAr)C5H3N}PdCl] (Ar = 4-i-PrC6H4 (3a), 2,6-i-Pr2C6H3 (3b)) and [{2-(C6H4-2′-O)-6-(CMe2NHAr)C5H3N}PdCl] (Ar = 4-i-PrC6H4 (4a), 2,6-i-Pr2C6H3 (4b)), respectively, on reaction with an aqueous sodium chloride solution. Treating each of 3a, 3b, 4a and 4b with two equivalents of di-p-tolyliodonium triflate at 100 °C in a toluene/acetonitrile mixture affords varying amounts of 4-chlorotoluene along with the 4-iodotoluene by-product with the conversions highly dependent on the steric and backbone properties of the pincer complex employed (viz.4a > 3a > 4b > 3b); notably, the least sterically bulky and most flexible amine-containing 4a reaches 90% conversion to 4-chlorotoluene in 15 h as opposed to 17% for imine-containing 3b. In the case of 3a, the inorganic palladium species recovered from the reaction has been identified as the Pd(ii) salt [{2-(C6H4-2′-O)-6-(CMeN(4-i-PrC6H4)C5H3N}Pd(NCMe)][O3SCF3] (5a), which was independently prepared by the reaction of 3a with silver triflate in acetonitrile. Single crystal X-ray structures are reported for HL1a, HL2a, 1a, 1b, 2a, 2b, 3a and 5a. This journal is
New Reagent Systems for Electrophilic Chlorination of Aromatic Compounds: Organic Chlorine-Containing Compounds in the Presence of Silica
Smith, Keith,Butters, Michael,Paget, Walter E.,Nay, Barry
, p. 1155 - 1156 (1985)
In the presence of silica, a number of chlorine-containing organic compounds, such as N,N-dichlorourethane, dichloramine-T, and t-butyl hypochlorite, become active electrophilic reagents capable of controlled monochlorination of aromatic compounds under mild conditions; for example, t-butyl hypochlorite/silica chlorinates alkylbenzenes, naphthalene, and anisole readily at 25 deg C; N,N-dichlorourethane/silica chlorinates benzene within 2 days 50 deg C.
Electrophilic aromatic chlorination and haloperoxidation of chloride catalyzed by polyfluorinated alcohols: A new manifestation of template catalysis
Ben-Daniel, Revital,De Visser, Samuel P.,Shaik, Sason,Neumann, Ronny
, p. 12116 - 12117 (2003)
We have demonstrated that a polyfluorinated alcohol, 2,2,2-trifluoroethanol, solvent enables haloperoxidase type activity and the oxychlorination of arenes (benzene and its alkylated derivatives) without a metal catalyst. The polyfluorinated alcohol has a dual function; it catalyzes electrophilic chlorination of less reactive arenes by several orders of magnitude and oxidation of chloride at lower H+ concentrations. DFT calculations show that a complementary charge template in the transition state explains the catalysis of the electrophilic chlorination. Copyright
Solvolysis of some arenediazonium salts in binary EtOH/H2O mixtures under acidic conditions
Pazo-Llorente, Roman,Bravo-Diaz, Carlos,Gonzalez-Romero, Elisa
, p. 3421 - 3428 (2003)
We have determined the product distribution, the rate constants for dediazoniation product formation, and the solvolytic rate constants for 2-, 3-, and 4-methylbenzenediazonium ions (2-, 3-, and 4-MBD, respectively) loss in acidic ethanol/water mixtures over the whole composition range by a combination of spectrophotometric (UV/Vis) and high performance liquid chromatography (HPLC) measurements. The observed rate constants (kobs) for substrate loss are equal to those for product formation, and they remain essentially constant (2-MBD) with changing solvent composition but increase by a factor of ≈2 (4MBD) on going from water to 100% EtOH. Up to four dediazoniation products - cresols (ArOH), chlorotoluene (ArCl), methylphenetole (ArOEt), and toluene (ArH) - were detected, depending on the solvent composition; the major dediazoniation products were the ArOH and ArOEt derivatives. The product selectivity (S) of the reaction towards nucleophiles is low and essentially constant with changing solvent composition, and good linear correlations between log kobs and Yc1 (solvent ionizing power) were observed for the three ArN2+ ions. All data are consistent with the rate-determining formation of an aryl cation, which reacts immediately with available nucleophiles. The data suggest that the distribution of neutral and anionic nucleophiles in the neighborhood of the ground state arenediazonium ion remains essentially unchanged upon dediazoniation, the observed product distribution reflecting the concentrations of nucleophiles in their immediate environment (i.e., in the first solvation shells of the arenediazonium ions). Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.
