Chlorine Atom Transfer Research Articles

The reduction of (chloromethyl)pyridines and (chloromethyl)quinolines by triphenyltin hydride. The nature of the chlorine atom transfer step

Application de la theorie des orbitales moleculaires a la comprehension du transfert d'un atome de chlore d'un chlorure heteroarylmethyl azote sur le radical triphenyltine. Un transfert d'electrons semble etre en cause

ChemInform Abstract: Kinetic and Thermochemical Parameters of Chlorine Atom Transfer Reactions from CF3Cl, CF3CF2Cl, CF2ClCF2Cl, and CF2ClCFCl2 in the Gas Phase.

ChemInformVolume 20, Issue 33 Preparative Organic Chemistry ChemInform Abstract: Kinetic and Thermochemical Parameters of Chlorine Atom Transfer Reactions from CF3Cl, CF3CF2Cl, CF2ClCF2Cl, and CF2ClCFCl2 in the Gas Phase. R. A. TACCONE, R. A. TACCONE Dep. Fisicoquim., Univ. Nac. Cordoba, 5016 Cordoba, Argent.Search for more papers by this authorO. SALINOVICH, O. SALINOVICH Dep. Fisicoquim., Univ. Nac. Cordoba, 5016 Cordoba, Argent.Search for more papers by this authorE. H. STARICCO, E. H. STARICCO Dep. Fisicoquim., Univ. Nac. Cordoba, 5016 Cordoba, Argent.Search for more papers by this author R. A. TACCONE, R. A. TACCONE Dep. Fisicoquim., Univ. Nac. Cordoba, 5016 Cordoba, Argent.Search for more papers by this authorO. SALINOVICH, O. SALINOVICH Dep. Fisicoquim., Univ. Nac. Cordoba, 5016 Cordoba, Argent.Search for more papers by this authorE. H. STARICCO, E. H. STARICCO Dep. Fisicoquim., Univ. Nac. Cordoba, 5016 Cordoba, Argent.Search for more papers by this author First published: August 15, 1989 https://doi.org/10.1002/chin.198933097Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume20, Issue33August 15, 1989 RelatedInformation

Kinetic and thermochemical parameters of chlorine atom transfer reactions from CF3Cl, CF3CF2Cl, CF2ClCF2Cl, and CF2ClCFCl2 in gas phase

AbstractThe following reactions: equation image were studied over the temperature ranges 533–687 K, 563–663 K, and 503–613 K for the forward reactions respectively and over 683–763 K, for the back reaction. Arrhenius parameters for chlorine atom transfer were determined relative to the combination of the attacking radicals. The ΔHr°(1) = −3.95 ± 0.45 kcal mol−1 was calculated and from this value the ΔH∮(C2F5Cl) = −2.66.3 ± 2.5 kcal mol−1 and D(C2F5‐Cl) = 82.0 ± 1.2 kcal mol−1 were obtained. Besides, the ΔHr°(2) was estimated leading to D(CF2ClCF2Cl) = 79.2 ± 5 Kcal mol−1. The bond dissociation energies and the heat of formation are compared with those of the literature. The effect of the halogen substitutents as well as the importance of the polar effects for halogen transfer processes are discussed.

Kinetic study of gas‐phase reactions with CF2Cl2 and CFCl3. Analysis using the transition state theory (TST) of the chlorine atom transfer reactions by CF3 and CH3 radicals from halomethanes

AbstractThe following gas‐phase reactions: equation image were studied by the competitive method with CF3I as the source of radicals. The kinetic parameters obtained in the temperature range 533–613 K and 503–613 K respectively for chlorine atom transfer reactions are given by: where θ = 2.303 RT (cal mol−1).The Arrhenius A values were calculated for seven chlorine atom transfer reactions (CF2Cl2, CFCl3, CCl4 with CF3 radicals; CF3Cl, CF2Cl2, CFCl3 and CCl4 with CH3 radicals) by using the thermochemical kinetic version of the Transition State Theory (TST).

Steric and electronic effects on atom transfer reactions of Re(CO)4L.cntdot. radicals with organic halides and tributylstannane

Re(CO)/sub 4/L x (L = CO, P(OR)/sub 3/, PR/sub 3/, AsEt/sub 3/) radicals, generated by laser flash photolysis of L(CO)/sub 4/Re-Re(CO)/sub 4/L, react with halogen atom donors (CH/sub 2/Br/sub 2/, CHCl/sub 3/, CCL/sub 4/) or hydrogen atom donors (HSn(n-Bu)/sub 3/) in solution to produce cis-Re(CO)/sub 4/LX (X = H, Cl, Br). Bimolecular rate constants for halogen and hydrogen atom transfers to Re(CO)/sub 4/L x were measured by following the decay of the transient Re(CO)/sub 4/L x absorbance in the 550-nm region. The rate constants for both the halogen and hydrogen atom transfer processes are influenced by steric and electronic properties of the substituent L. Both bromine and chlorine atom transfer processes depend to a similar extent on the electronic properties of L. The bromine atom transfer reactions show a slightly greater steric dependence than the chlorine atom transfer reactions. The steric dependence of the hydrogen atom transfer reaction is similar to that of the halogen atom transfers, but the dependence on the electronic properties of L is smaller. Increasing electron density at the metal center enhances the rate of atom transfer; polar effects are more evident in the halogen atom transfer. Rate constants for both atom transfer reactions fit a more » two-parameter free energy relationship, wherein electronic and steric effects of L are represented. « less

Reaction of chlorodifluoropropenoates with potassium fluoride

Reaction of methyl 3-chlorodifluoropropenoate (I) with potassium fluoride afforded methyl trifluoropropenoate (II) which was dimerized to dimethyl perfluro-4-methyl-2-pentenedioate (III). The reaction rate of I was not affected by the presence of the monomer II. Methyl 2-chlorodifluoropropenoate (VII) on treatment with potassium fluoride underwent dimerization and the unstable dimer X was transformed at -20 °C into methyl 2-chloro-3,5,5-trifluoro-4-methoxycarbonyl-2,4-pentadienoate (XIII) and dimethyl 2-chloro-3-fluoro-4-trifluoromethyl-2-pentenedioate (XIV). These reactions involve a transfer of chlorine atom from the dimer X to the primarily formed 1-chloro-3,3,3-trifluoro-1-methoxycarbonylethanide (VIIa) which is transformed by this carbanion interconversion into methyl 2,2-dichlorotrifluoropropanoate (XI). The propenoate VII adds methanol in the presence of potassium fluoride whereas the propenoate I does not react under these conditions.

ChemInform Abstract: THE RATE CONSTANT FOR COMBINATION OF A TRICHLOROMETHYL RADICAL WITH CYCLOHEXYL OR N‐HEXYL RADICALS. AN EVIDENCE FOR THE VALUE OF THE RATE CONSTANT FOR A CHLORINE ATOM TRANSFER

Chemischer InformationsdienstVolume 11, Issue 36 Preparative Organic Chemistry ChemInform Abstract: THE RATE CONSTANT FOR COMBINATION OF A TRICHLOROMETHYL RADICAL WITH CYCLOHEXYL OR N-HEXYL RADICALS. AN EVIDENCE FOR THE VALUE OF THE RATE CONSTANT FOR A CHLORINE ATOM TRANSFER Z. B. ALFASSI, Z. B. ALFASSISearch for more papers by this author Z. B. ALFASSI, Z. B. ALFASSISearch for more papers by this author First published: September 9, 1980 https://doi.org/10.1002/chin.198036126AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume11, Issue36September 9, 1980 RelatedInformation

Kinetics of the reactions of silicon compounds. Part 10. Kinetics and mechanism of the gas-phase thermal reactions of trichloro-(1,1-difluoroethyl)silane. An intramolecular halogen exchange reaction

The gas-phase thermal isomerisation of trichloro-(1,1-difluoroethyl)silane (I) to chloro-(1,1-dichloroethyl)-difluorosilane (II) is a first-order homogeneous process at 375–416 K and 11–67 mmHg initial pressure. The reaction is unaffected by the presence of the radical inhibitors 2,3-dimethylbut-2-ene and nitric oxide, and it is concluded that the rate-determining step is a unimolecular isomerisation of (I) to dichloro-(1-chloro-1-fluoroethyl)fluorosilane (III), which then undergoes a secondary fast isomerisation to the observed product (II). [graphic omitted], log10k1/s–1=(13.38 ± 0.05)–(127.2 ± 0.4) kJ mol–1/RT ln 10 The data suggest a transition state in which the fluorine atom transfer is more advanced than the chlorine atom transfer. The minor products vinyl chloride and dichlorodifluorosilane are shown to arise from thermal and chemically activated decomposition of the initially formed (II) and/or (III).

Preparation of some substituted Bicyclo[4,2,0]octa-1,3,5-trienes (benzocyclobutenes)

The reaction of benzyne (generated by the thermolysis of o- diazoniobenzoate) with the following alkenes has been examined: 1,1-dichloroethene (5) (vinylidene chloride), 1,1-dichloro-propene (7), 1,1-dichloro-2-methylpropene (17), 2-methylprop-1-en-1-yl acetate (18) and 2-chloro-prop-2-enenitrile (α-chloroacrylonitrile) (22). Substituted bicyclo[4,2,0]octa-1,3,5-trienes resulting from 2+2 cycloaddition were obtained from (5), (7), and (22), while the reaction involving the en01 acetate (18) gave only 'ene' product, and that involving (17) gave an intractable mixture. (Z)- and (E)-1-Chloro-2-(o-chlorophenyl)propene were obtained as minor products in the reaction of benzyne with (7): these products result from a chlorine atom transfer to the aromatic ring, and a novel mechanism involving a diradical → carbene rearrangement is postulated.

A study of the mechanism of the Sandmeyer reaction

The one-electron-transfer mechanism for the Sandmeyer reaction, proposed by W. A. Waters in 1942 has now been confirmed by diagnostic experiments. Its initial stage, Ar ·N + 2 + Cu + → Ar · + N 2 + Cu 2+ , has been shown to produce free aryl radicals capable of initiating vinyl polymerization; this observation is also true for related reactions of diazonium salts for which analogous one-electron-transfer mechanisms have been suggested. The cupric ions thus produced are oxidizers that, like ferric ions, can effect chain-ending of vinyl polymerization. They bring about the final step in the Sandmeyer reaction by a similar process that apparently involves chlorine atom transfer; Ar · + Cl—Cu—Cl → Ar —Cl + Cu—Cl. Product studies show that cupric ions are needed to enable the Sandmeyer reaction to give aryl chlorides in high yield; in their absence other reactions of aryl radicals can occur extensively. Molecular weight measurements with acrylonitrile polymers indicate that in dilute solution up to 35% of the initial aryldiazonium cations can produce free aryl radicals by interaction with cuprous ions in chloride solutions, but that in more concentrated solutions the secondary reaction with the cupric chloride generated occurs so extensively that the full cycle of the Sandmeyer reaction becomes predominantly an intramolecular process.