Halogen Interchange Research Articles

Theoretical study for conformational analysis and kinetics on the internal halogen exchange thermally induced of trichloro-(1,1-difluoroethyl)silane in the gas phase

Consecutive first-order, homogeneous intramolecular fluorine-chlorine exchange reactions of trichloro-(1,1-difluoroethyl)silane have been theoretically studied using ab initio post-Hartree-Fock G4MP2 and DFT (B3LYP, M06, M06-2X) levels of theory. The reactions were studied at 127 °C and 0.1 Torr of temperature and pressure respectively, yielding (1-choro-1-fluoroethyl)-dichlorofluorosilane, and chloro-difluoro(1,1-dichloroethyl)silane. A very good agreement has been found between B3LYP/6-311+G(2df,p) calculations and previously reported experimental results. Conformational mobility in the structure of the intermediate and final product was studied in order to assign the highest and lowest in energy conformers. Analysis of activation parameters, Natural Bond Order (NBO) and Atoms In Molecules (AIM) suggests that in the first exchange reaction, the fluorine atom is almost completely transferred to silicon prior to chlorine migration, producing a penta-coordinated Si center and a positive-charged carbon in the transition state (TS). The second fluorine-chlorine switch proceeds through a more synchronized three-membered cyclic transition state, as opposed to the results obtained in a previous work, which proposes that the cyclic TS take place in the first halogen interchange. The differences in synchronicity (Sy) parameters between the two reactions steps are attributed to the difference in the uniformity of the electron distribution. According to IRC calculations, transition states are early and both exchanges are exothermic.

Synthesis of End-Functionalized Polymers by Means of Living Anionic Polymerization. 8. Reactions of Living Anionic Polymers with α,ω-Dihaloalkanes

In order to prepare well-defined polymers with halogen end groups, anionic living polymers of isoprene and styrene were allowed to react with excess amounts of α,ω-dihaloalkanes in THF at −78 °C. The monosubstitution reactions of 1,3-dichloropropane with these anionic living polymers proceeded cleanly to afford quantitatively the polymers with chlorine end groups that possessed controllable molecular weights and narrow molecular weight distributions. On the other hand, the reactions of the anionic living polymers with either α,ω-dibromoalkanes or α,ω-diiodoalkanes proceeded competitively with side reactions leading to dimer formation of the starting living polymers. Thus, the bromine- and iodine-terminated polymers were obtained in 12−93% yields along with undesirable dimers. As side reaction candidates, we speculated on metal−halogen interchange and/or single electron transfer pathways followed by coupling reactions between the reaction intermediates generated by both pathways. By end-capping the polysty...

A new approach to the synthesis of 3-fluoro and 3,3-difluoro acrylic acids

Although variously fluorinated esters of acrylic acid have received important applications as monomers in the polymer field, the chemistry of genuine fluoroacrylic acids and esters, i.e. bearing fluorine atoms at the α and/or β positions, has received scarce attention, except for the promising α-fluoroacrylates. This is mainly owing to synthesis problems. Two routes to some (previously unknown) β-fluoroacrylic esters have already been reported [H. Molines and C. Wakselman, J. Fluorine Chem., 25 (1984) 447. idem., J. Fluorine Chem. 45 (1989) 155; IXth European Symposium on Fluorine Chemistry, Leicester (UK), September 4–8, 1989]. We propose here a new, short sequence affording the β-fluoroacrylic acid 1 directly as a single E isomer in a reasonable yield (25% overall), starting from vinyl fluoride and carbon tetrabromide. ▪ The same sequence was applied to 1,1-dipfluoroethylene (vinylidene fluoride) as a possible route to 3,3-difluoroacrylic acid 2. The dehydrobromination step proved to be delicate due to halogen interchange [J. Leroy, H. Molines and C. Wakselman, J. Org. Chem., 52 (1987) 290] and subsequent easy formation of 3,3,3-trifluoropropanoic acid 3 in basic medium.

ChemInform Abstract: Halogen Interchange During Complex Formation between N‐Halosuccinimides and Quaternary Ammonium Halides.

ChemInformVolume 18, Issue 20 Article ChemInform Abstract: Halogen Interchange During Complex Formation between N-Halosuccinimides and Quaternary Ammonium Halides. L. EBERSON, L. EBERSON Div. Org. Chem., Chem. Center, Univ., 22100 Lund, SwedenSearch for more papers by this authorM. FINKELSTEIN, M. FINKELSTEIN Div. Org. Chem., Chem. Center, Univ., 22100 Lund, SwedenSearch for more papers by this authorB. FOLKESSON, B. FOLKESSON Div. Org. Chem., Chem. Center, Univ., 22100 Lund, SwedenSearch for more papers by this authorG. A. HUTCHINS, G. A. HUTCHINS Div. Org. Chem., Chem. Center, Univ., 22100 Lund, SwedenSearch for more papers by this authorL. + JOENNSSON, L. + JOENNSSON Div. Org. Chem., Chem. Center, Univ., 22100 Lund, SwedenSearch for more papers by this authorR. LARSSON, R. LARSSON Div. Org. Chem., Chem. Center, Univ., 22100 Lund, SwedenSearch for more papers by this authorW. M. MOORE, W. M. MOORE Div. Org. Chem., Chem. Center, Univ., 22100 Lund, SwedenSearch for more papers by this authorS. D. ROSS, S. D. ROSS Div. Org. Chem., Chem. Center, Univ., 22100 Lund, SwedenSearch for more papers by this author L. EBERSON, L. EBERSON Div. Org. Chem., Chem. Center, Univ., 22100 Lund, SwedenSearch for more papers by this authorM. FINKELSTEIN, M. FINKELSTEIN Div. Org. Chem., Chem. Center, Univ., 22100 Lund, SwedenSearch for more papers by this authorB. FOLKESSON, B. FOLKESSON Div. Org. Chem., Chem. Center, Univ., 22100 Lund, SwedenSearch for more papers by this authorG. A. HUTCHINS, G. A. HUTCHINS Div. Org. Chem., Chem. Center, Univ., 22100 Lund, SwedenSearch for more papers by this authorL. + JOENNSSON, L. + JOENNSSON Div. Org. Chem., Chem. Center, Univ., 22100 Lund, SwedenSearch for more papers by this authorR. LARSSON, R. LARSSON Div. Org. Chem., Chem. Center, Univ., 22100 Lund, SwedenSearch for more papers by this authorW. M. MOORE, W. M. MOORE Div. Org. Chem., Chem. Center, Univ., 22100 Lund, SwedenSearch for more papers by this authorS. D. ROSS, S. D. ROSS Div. Org. Chem., Chem. Center, Univ., 22100 Lund, SwedenSearch for more papers by this author First published: May 19, 1987 https://doi.org/10.1002/chin.198720071AboutPDF 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. Volume18, Issue20May 19, 1987 RelatedInformation

Metal—halogen interchange between [formula omitted]-butyllithium and 1-iodo-5-hexenes provides no evidence for single-electron transfer

No products attributable to cyclization of 5-hexen-1-yl radicals have been detected in reactions of t -butyllithium with 1-iodo-5-hexenes at −78°C. Such experiments provide no evidence for the intermediacy of free-radicals in the metal—halogen interchange of primary alkyliodides with t -C 4H 9Li.

Reactions of 1-halo-5-hexenes with alkyllithiums. Evidence for a pronounced halogen effect on the mechanism of the metal—halogen interchange reaction of primary alkyl halides

Reaction of t -BuLi with 1-halo-5-hexenes and 1-halo-6-methyl-5-heptenes at −78°C has revealed that, whereas 1° alkyl iodides are cleanly converted to alkyllithiums in a non-radical process, the corresponding 1° alkyl bromides undergo interchange at least partially via a radical-mediated, SET pathway.

4-bromo-3,3-dimethyl-1-butene: a new probe for radical intermediates in reactions in strongly basic media

The preparation, isolation and purification of the title bromide ( 1) are described, and the application of 1 as a mechanistic probe is demonstrated in the metal—halogen interchange reaction with tert -butyllithium.

Chemistry of Transition Metals. V. Further Studies on the Mechanism of Reaction of n-Alkyl Chlorides with Metals of the First Transition Period

The rate of reaction of n-propyl chloride on polycrystalline evaporated titanium films has been shown to follow a strictly half-order rate law in the pressure range 0.1–0.01 Torr at 220 °C. The reaction rate was not influenced by the product propene. Experiments using a mixture of 1-bromopropane and l-chloropropane-1-d1 gave no indication of halogen interchange on either titanium or chromium, thus excluding rapid, reversible dissociative adsorption of the carbon–halogen bond as an explanation of the half-order rate law.

Halogen Interchnge Reaction of Halobenzenes in the Presence of Fused Salts

When the reaction of C6H5l and Br2 were carried out in fused salt of alkali metal chloride system containing CuCl, halogen interchange reaction was mainly observed to give C6H5Br, but in the presence of of similar fused salt containing ZnCl2, large amounts of C6H5Cl were obtained together with C6H5Br. Analogous halogen interchange reaction of C6H5Br with C12 in the presece of such fused salts gave Ca-WI along with small amounts of C6H4H2 and C6H5Brcl2.When Ca-Ur was chlorinated by Cl2 in the presence of C6H5NO2 as radical inhibitor at 350C, halogen interchange reaction and chlorination were not prohibited in the presence of ZnCl2, in fused salts, but the both reactions were prohibited in the presence of the CuCl.Consideration from these results, reaction temperature and conposition of fused salts dominate the products distributions.It was supposed that in fused salt containing ZnCl2, the halogen interchange reaction proceeded mainly through an ionic mechanism and the halogenation reaction could be explained as a Friedel-Crafts type reaction. In the case of CuCl, the reaction seemed to proceed through a radical mechanism.

Catalysis by rhodium(I) in nucleophilic substitutions at rhodium(III)

The rates of halogen interchange in trans-[Rh(py)4X2]+(X = Cl or Br; py = pyridine) have been found to be markedly inhibited by oxygen and to be catalysed by both primary and secondary alcohols. No corresponding effect has been observed for the related ethylenediamine complexes trans-[Rh(en)2X2]+: in this case catalytic halogen interchanges are induced only by the presence of stronger reducing agents. The mechanisms of these catalytic reactions are discussed and evidence is presented which shows the active catalyst to be a RhI species which is formed via a RhIII–H intermediate.

The catalysis of substitutions in the complexes trans-[Rh py4X2

The rates of halogen interchange in trans-[Rhpy4X2]X (X = Cl or Br) have been found to be markedly inhibited by oxygen and to be catalysed by both primary and secondary alcohols.

Reaction of chlorine‐containing polymers with living polymers

AbstractA graft polymer was prepared by means of the coupling reaction of chlorinated ethylene–propylene terpolymer with living polystyrene, obtained with a sodium–naphthalene complex as initiator, under various conditions; the grafting efficiency and the percentage of grafting are discussed. Poly(chloroprene), chlorinated butyl rubber, poly(vinyl chloride), poly(epichlorohydrin), and epichlorohydrin–ethylene oxide copolymer were also used as chlorine‐containing polymers. The grafting efficiencies were found to be in the following order: chlorinated butyl rubber > poly(epichlorohydrin) > epichlorohydrin‐ethylene oxide copolymer > chlorinated ethylene‐propylene terpolymer > poly(chloroprene) > poly(vinyl chloride). A graft polymer was obtained from the reaction between chlorinated ethylene–propylene terpolymer and living poly(isoprene), with butyllithium in benzene. The undesirable metal–halogen interchange reaction was considerable.

Preparation and characterization of some star‐and comb‐type branched polystyrenes

AbstractStar‐type polystyrenes, polymers with p branches attached to a common multifunctional center, and comb‐type polystyrenes, polymers with an average of p branches attached at random to a polymeric backbone, have been prepared by the reactions, respectively, of polystyryllithium of narrow chain length distribution with appropriate p‐functional molecules or with backbone polystyrene chains of narrow chain length distribution, containing the prerequisite number of benzylic‐type chloromethyl groups. The synthesis, isolation, and characterization of these types of polymers are illustrated by specific examples. Problems which are inherent to the system, e.g., metal–halogen interchange reactions, different reactivities of the chloromethyl groups, isomerization of the polystyryllithium, and other possible reactions and their consequences are discussed.

89. Acylation. Part X. Catalytic salt effects and halogen interchange between acyl, hydrogen, and saline halides: two factors in acylation in acetic acid

89. Acylation. Part X. Catalytic salt effects and halogen interchange between acyl, hydrogen, and saline halides: two factors in acylation in acetic acid

The Fischer Indole Synthesis. IV. Halogen Interchange during the Zinc Halide Induced Fischer Reactions of Acetophenone 2,6-Dihalophenylhydrazones1

The Fischer Indole Synthesis. IV. Halogen Interchange during the Zinc Halide Induced Fischer Reactions of Acetophenone 2,6-Dihalophenylhydrazones¹