Friedel

Distribution by Scientific Domains
Distribution within Chemistry

Kinds of Friedel

  • Catalyze friedel
  • asymmetric friedel
  • enantioselective friedel
  • intramolecular friedel


  • Selected Abstracts


    Arylation of Hydrocarbyl Ligands Formed from n -Alkanes through C,H Bond Activation of Benzene Using a Triruthenium Cluster

    EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 23 2009
    Makoto Moriya
    Abstract Triruthenium complex 2 containing a perpendicularly coordinated 1-pentyne ligand, which is one of the key intermediates of the reaction of triruthenium pentahydrido complex 1 with n -pentane, reacts with benzene to yield ,3 -benzyne,,3 -pentylidyne complex 5 by C,H bond activation. ,-H elimination form the ,3 -penytylidyne ligand occurred upon heating to yield ,3 -pentenylidene complex 6, which was followed by the formation of closo -ruthenacyclopentadiene complex 8 by the connection of the two hydrocarbyl moieties placed on each face of the triruthenium plane with partial metal,metal bond breaking. Treatment of 8 with pressurized hydrogen resulted in exclusive liberation of n -pentylbenzene, which is difficult to synthesize by conventional Friedel,Crafts alkylation. These sequential transformations correspond to the formation of linear alkylbenzene by the reaction of pentane with benzene on a trimetallic plane. ( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source]


    Planar-Chiral Thioureas as Hydrogen-Bond Catalysts

    EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 12 2010
    Jakob F. Schneider
    Abstract The synthesis of the first enantiopure planar-chiral thiourea catalysts is herewith described. New catalysts 1,3 were applied in asymmetric transformations, such as the Friedel,Crafts alkylation of indole, as well as in the transfer hydrogenation of nitroolefins. Bifunctional catalysts 2 and 3 exhibit enhanced activity in the investigated reactions, demonstrating their potential for organic synthesis. [source]


    Regioselective Arylations of ,-Amido Sulfones with Electron-Rich Arenes through Friedel,Crafts Alkylations Catalyzed by Ferric Chloride Hexahydrate: Synthesis of Unsymmetrical and Bis-Symmetrical Triarylmethanes

    EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 9 2010
    Ponnaboina Thirupathi
    No abstract is available for this article. [source]


    Synthesis of 3-(Tosylalkyl)indazoles and their Desulfonylation Reactions , A New Entry to 3-Substituted Indazoles by an Unprecedented Friedel,Crafts Process

    EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 19 2009
    Silvia Campetella
    Abstract Reaction of indazoles with aldehydes in the presence of p -toluenesulfinic acid affords the corresponding sulfonyl indazoles in satisfactory yields. The reported Friedel,Crafts process is rather unusual on indazoles because of the reduced electronic density of the heterocycle. The obtained sulfonyl indazoles can be desulfonylated under reductive conditions, finally leading to 3-alkylated indazoles.( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source]


    Stereoselective Synthesis of 2,6-Disubstituted-4-Aryltetrahydropyrans Using Sakurai,Hosomi,Prins,Friedel,Crafts Reaction

    EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 10 2009
    Udagandla C. Reddy
    Abstract The reaction of aldehydes with allyltrimethylsilane in arene solvents gives symmetrical 2,6-disubstituted-4-aryltetrahydropyrans in good yields. The reaction is highly stereoselective. ( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source]


    Synthesis of Novel Angular Heterocyclic Lignans by an InCl3 -Catalyzed Friedel,Crafts-Type Cyclization

    EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 10 2008
    Matthieu Dorbec
    Abstract The synthesis of a 1-aryltetralin privileged structure-based library of novel angular heterocyclic lignans is described. Indolotetralins 3, tetrahydroquinolinotetralins 4, and thiochromanotetralins 5 were obtained from the methyl ester of thuriferic acid 2 according to a three-step procedure involving an InCl3 -catalyzed Friedel,Crafts-type cyclization as the key step.( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source]


    On the Functionalization of [2.2](1,4)Phenanthrenoparacyclophane,,

    EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 12 2007
    Henning Hopf
    Abstract Two routes for preparing functionalized [2.2](1,4)phenanthrenoparacyclophanes are described: either the parent system 2 is subjected to electrophilic substitution (bromination, Friedel,Crafts acylation, Rieche formylation: preparation of 5, 6, 7, 11 and 12) or the desired substituents are incorporated in the early stages of the synthesis by the preparation of the corresponding functionalized styryl paracyclophanes and their photocyclization to the respective phenanthrenocyclophanes. By these specific routes various bromides (22a,b), ethers (28a,c) and phenols (29a,b) were synthesized. The latter derivatives, on oxidation, furnish para - (31) and ortho -quinonophanes (30, 32, 33), useful substrates for the preparation of cyclophanes containing phenazine subunits (36). The stilbene , phenanthrene photocyclization can also be employed for the preparation of benzothiophenophanes, e.g. 43 and 44, from the respective precursors. ( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source]


    Stereoselective Total Synthesis of Xestodecalactone C

    HELVETICA CHIMICA ACTA, Issue 9 2009
    Karuturi Rajesh
    Abstract A simple and highly efficient stereoselective total synthesis of xestodecalactone C (IIb), a polyketide natural product, was achieved (Scheme,2). The synthesis involved Keck's asymmetric allylation, a iodine-induced electrophilic cyclization, and an intramolecular Friedel,Crafts acylation as key steps. [source]


    Selective Synthesis of 1,4-Dialkylbenzenes from Terephthalic Acid

    ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 13 2010
    Andrea Bramborg
    Abstract Terephthalic acid reacts with alkyl halides under Birch conditions to substituted 1,4-cyclohexadienes in high yields and good stereoselectivities. Electrophiles containing ester or nitrile groups undergo a surprising fragmentation under the reaction conditions. Subsequent treatment with chlorosulfonic acid proceeds by an interesting tandem decarbonylation/decarboxylation, affording 1,4-dialkylbenzenes in excellent regioselectivity. Thus our new method is superior to classical Friedel,Crafts alkylations. [source]


    Enantioselective Organocatalytic Synthesis of Arylglycines via Friedel,Crafts Alkylation of Arenes with a Glyoxylate Imine

    ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 9 2010
    Dieter Enders
    Abstract The enantioselective organocatalytic synthesis of arylglycines has been developed employing 1,mol% of an enantiopure N -triflyl phosphoramide Brnsted acid as organocatalyst. Various differently substituted phenylglycine derivatives can be synthesized in good to excellent yields and enantiomeric excesses based on a Friedel,Crafts alkylation of electron-rich arenes with a glyoxylate imine. A novel protocol for the deprotection of the N - tert -butylsulfonyl (Bus) group has also been developed. [source]


    Development of Diphenylamine-Linked Bis(imidazoline) Ligands and Their Application in Asymmetric Friedel,Crafts Alkylation of Indole Derivatives with Nitroalkenes

    ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 7 2010
    Han Liu
    Abstract The new diphenylamine-linked bis(imidazoline) ligands were prepared through Kelly-You's imidazoline formation procedure mediated by Hendrickson's reagent in good yields. The novel ligands were tested in the asymmetric Friedel,Crafts alkylation of indole derivatives with nitroalkenes. In most cases, good yields (up to 97%) and excellent enantioselectivities (up to 98%) can be achieved. The optimized bis(imidazoline) ligand with trans -diphenyl substitution on the imidazoline ring gave better enantioselectivity than the corresponding bis(oxazoline) ligand. [source]


    Facile Creation of 3-Indolyl-3-hydroxy-2-oxindoles by an Organocatalytic Enantioselective Friedel,Crafts Reaction of Indoles with Isatins

    ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 5 2010
    Jing Deng
    Abstract The first direct enantioselective Friedel,Crafts reaction of indoles with isatins has been developed. The process is catalyzed by simple cupreine under mild reaction conditions and affords synthetically and biologically interesting, chiral 3-indolyl-3-hydroxy-2-oxindoles in good yields (68,97%) and with high enantioselectivities (76,91%). [source]


    Highly Enantioselective Friedel,Crafts Reaction of Indole with Alkylidenemalonates Catalyzed by Heteroarylidene Malonate-Derived Bis(oxazoline) Copper(II) Complexes

    ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 18 2009
    Yan-Jin Sun
    Abstract A series of cheap and easily accessible heteroarylidenemalonate-derived bis(oxazoline) ligands 1 and 2 were synthesized and their copper(II) complexes were applied to the catalytic Friedel,Crafts reaction between indoles and diethyl alkylidenemalonates, Excellent asymmetric enantioselectivities were afforded for the S -enantiomer (up to >99% ee) in isobutyl alcohol, and the R -enantiomer (up to 96.5% ee) in dichloromethane. [source]


    Synthesis of Functionalized Indoles with an ,-Stereogenic Ketone Moiety Through an Enantioselective Friedel,Crafts Alkylation with (E)-1,4-Diaryl-2-butene-1,4-diones

    ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 14-15 2009
    Gonzalo Blay
    Abstract Chiral complexes of BINOL-based ligands with hafnium tert -butoxide catalyze the enantioselective Friedel,Crafts alkylation of indoles with (E)-1,4-diaryl-2-butene-1,4-diones at room temperature, with good yields and ee up to 94%. Hafnium(IV) was found to be a more effective Lewis acid than other frequently used metal ions such as titanium(IV) or zirconium(IV). Unlike the enantioselective Friedel,Crafts alkylation of indoles with ,,,-unsaturated compounds where the stereogenic center is generated in the ,-position to a carbonyl group, the Friedel,Crafts alkylation with 2-butene-1,4-diones described here generates an ,-stereogenic center with respect to one of the carbonyl groups. This can be regarded as an inversion of the normal reactivity pattern or umpolung. The enantioselective Friedel,Crafts alkylation of indoles with (E)-4-oxo-4-phenylbutenoates using a zirconium(IV)-BINOL catalyst is also reported. This reaction takes place regioselectively at the carbon in the ,-position to the ketone carbonyl group, generating an ,-ester stereogenic center. [source]


    Iron(III)-Catalyzed Intramolecular Friedel,Crafts Alkylation of Electron-Deficient Arenes with ,-Activated Alcohols

    ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 14-15 2009
    Marco Bandini
    Abstract "Deficient" but "efficient", the first example of a catalytic Friedel,Crafts alkylation of arenes, carrying electron-withdrawing groups, with alcohols is reported. The optimized iron(III) chloride (97%) catalyzed allylation, benzylation and propargylation procedures open an access to a range of tetrahydronaphthalenes, tetrahydroisoquinolines and tetrahydrobenzo[d]azepines featuring tertiary benzylic stereocenters in excellent yields (up to 92%) and short reaction times. [source]


    Gold-Catalyzed Intermolecular Reactions of (Z)-Enynols with Indoles for the Construction of Dihydrocyclohepta[b]indole Skeletons through a Cascade Friedel,Crafts/Hydroarylation Sequence

    ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 10 2009
    Yuhua Lu
    Abstract An efficient domino approach for the synthesis of indole-fused carbocycles and their analogues from the reactions of suitably substituted (Z)-enynols with indoles or pyrroles under mild reaction conditions was developed. This methodology is realized by a tandem reaction using Au/Ag catalysts, which could catalyze both of the Friedel,Crafts and the hydroarylation reaction in the same vessel. [source]


    A Catalytic and Enantioselective Synthesis of trans- 2-Amino-1- aryltetralins

    ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 6 2009
    Saumen Hajra
    Abstract The bis-oxazoline-copper complex-catalyzed aziridination of alkenes followed by an intramolecular Friedel,Crafts alkylation of the tethered and in situ generated aziridine provides a one-pot, general and efficient method for the synthesis of trans -2-amino - 1-aryltetralins from a mixture of 2- arylethylstyrenes (E/Z,85:15) with excellent dia- stereo- (dr>99:1) and enantioselectivities (up to 92% ee). [source]


    An Efficient Enantioselective Method for Asymmetric Friedel,Crafts Alkylation of Indoles with ,,,-Unsaturated Aldehydes

    ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 5 2009
    Liang Hong
    Abstract The Lewis base-Lewis base bifunctional catalytic system has been developed and successfully applied to the asymmetric Friedel,Crafts alkylation of indoles with ,,,-unsaturated aldehydes. The reactions are promoted by chiral diphenylprolinol trimethylsilyl ether in the presence of triethylamine. By this protocol, optically active 3-substituted indoles can be obtained in an organocatalytic process that is free of Lewis or protic acid in high yields with up to 98% ee. Besides, this reaction could be carried out on a gram scale without any loss in the enantioselectivity. [source]


    Ligand-Free Silver(I)-Catalyzed Intramolecular Friedel,Crafts Alkylation of Arenes with Allylic Alcohols

    ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 3 2009
    Marco Bandini
    Abstract The silver-catalyzed direct activation of allylic alcohols as electrophilic partners for intramolecular Friedel,Crafts alkylation of arenes is described. Use of silver triflate (AgOTf; 10 mol%) enabled functionalized 1-vinyl-1,2,3,4-tetrahydronaphthalenes and a 4-vinyl-1,2,3,4-tetrahydroisoquinoline to be isolated in good yields with high levels of regiochemistry, under a ligand-free regime. [source]


    Development of a Supported Ionic Liquid Phase (SILP) Catalyst for Slurry-Phase Friedel,Crafts Alkylations of Cumene

    ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 3 2009
    J. Joni
    Abstract A supported ionic liquid phase (SILP) catalyst material has been developed based on a silica support coated with an acidic chloroaluminate ionic liquid. Compared to the results in a liquid-liquid biphasic reaction these materials showed in the isopropylation of cumene a clearly different selectivity which was found to be related to a reduction of the ionic liquid's acidity by the untreated silica support. By pretreating the support with a defined amount of ionic liquid for neutralization and removal of surface hydroxy groups, a well defined, very active and also very selective SILP catalyst for slurry phase Friedel,Crafts alkylation was obtained. [source]


    An Efficient Bismuth(III) Chloride-Catalyzed Synthesis of 1,1-Diarylalkenes via Friedel,Crafts Reaction of Acyl Chloride or Vinyl Chloride with Arenes

    ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 14 2006
    Hongbin Sun
    Abstract In the presence of catalytic amount of bismuth(III) chloride, the reactions of acyl chlorides or vinyl chlorides with arenes afforded 1,1-diarylalkenes in 25,82,% isolated yield. In the case of the reaction of acyl chlorides with arenes, the procedure includes an initial Friedel,Crafts acylation, subsequent formation of vinyl chlorides and final Friedel,Crafts-type vinylation of another arene molecule with vinyl chloride. This paper reports the first Lewis acid-catalyzed cleavage of the CCl bond of vinyl chloride and its application in the synthesis of multiply subtituted alkenes. [source]


    Synthesis of N-Heteroaryl(trifluoromethyl)hydroxyalkanoic Acid Esters by Highly Efficient Solid Acid-Catalyzed Hydroxyalkylation of Indoles and Pyrroles with Activated Trifluoromethyl Ketones

    ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 14 2005
    Mohammed Abid
    Abstract The synthesis of N-heteroaryl(trifluoromethyl)hydroxyalkanoic acid esters by solid acid-catalyzed Friedel,Crafts hydroxyalkylation of indoles and pyrroles with ethyl 3,3,3-trifluoropyruvate and ethyl 4,4,4-trifluoroacetoacetate is described. The inexpensive and readily available K-10 montmorillonite is found to be an efficient catalyst for the synthesis of a wide variety of trifluoromethylated indol-3-yl- and pyrrol-2-yl-hydroxypropionic and -butanoic acid esters. Using a series of substituted indoles and pyrroles the corresponding products were isolated in excellent yield (up to 98%) and 100% selectivity under mild experimental conditions, during very short reaction times. Beyond these, the ease of product isolation, catalyst stability and handling make this process an attractive, environmentally benign alternative for the synthesis of the target compounds. [source]


    Gold(III) Chloride-Catalyzed Addition Reactions of Electron-Rich Arenes to Methyl Vinyl Ketone

    ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 11 2003
    Gerald Dyker
    Abstract For the reaction of ,,,-unsaturated ketones with electron-rich arenes catalyzed by gold(III) chloride both, a Friedel,Crafts-type mechanism and an initial metallation, are evaluated. Gold(III) chloride has proven to be an efficient catalyst under very moderate reaction conditions, however, in the case of sterically demanding products HBF4 turned out to be the superior catalyst. [source]


    Synthesis and properties of novel organosoluble aromatic poly(ether ketone)s containing pendant methyl groups and sulfone linkages

    JOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2008
    Shou-Ri Sheng
    Abstract Several novel aromatic poly(ether ketone)s containing pendant methyl groups and sulfone linkages with inherent viscosities of 0.62,0.65 dL/g were prepared from 2-methyldiphenylether and 3-methyldiphenylether with 4,4,-bis(4-chloroformylphenoxy)diphenylsulfone and 4,4,-bis (3-chloroformylphenoxy)diphenylsulfone by electrophilic Friedel,Crafts acylation in the presence of N,N -dimethylformamide with anhydrous AlCl3 as a catalyst in 1,2-dichloroethane. These polymers, having weight-average molecular weights in the range of 57,000,71,000, were all amorphous and showed high glass-transition temperatures ranging from 160.5 to 167C, excellent thermal stability at temperatures over 450C in air or nitrogen, high char yields of 52,57% in nitrogen, and good solubility in CHCl3 and polar solvents such as N,N -dimethylformamide, dimethyl sulfoxide, and N -methyl-2-pyrrolidone at room temperature. All the polymers formed transparent, strong, and flexible films, with tensile strengths of 84.6,90.4 MPa, Young's moduli of 2.33,2.71 GPa, and elongations at break of 26.1,27.4%. 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]


    Synthesis of carvacrol by Friedel,Crafts alkylation of o -cresol with isopropanol using superacidic catalyst UDCaT-5

    JOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 10 2009
    Ganapati D. Yadav
    Abstract BACKGROUND: Alkylation of o -cresol with propylene or isopropyl alcohol (IPA) over solid acid catalysts results in the formation of carvacrol, which finds potential applications in the synthesis of fine chemicals, intermediates, specialty chemicals, flavours and fragrances. RESULTS: The present work covers evaluation of novel mesoporous superacidic catalysts namely UDCaT-4, UDCaT-5 and UDCaT-6 in the greener synthesis of carvacrol. The catalysts are modified versions of zirconia showing high catalytic activity, stability and reusability. The catalytic activity increases in the following order: UDCaT-5 > UDCaT-4 > UDCaT-6 > sulfated zirconia. The process was optimized and a mathematical model developed to describe the reaction pathway in liquid phase. Carvacrol could be efficiently obtained with a selectivity up to 82% at an isopropanol conversion of 98% after 2 h over UDCaT-5 at 180 C. CONCLUSION: The reaction is free from any external mass transfer as well as intraparticle diffusion limitations and is intrinsically kinetically controlled. An overall second-order kinetic equation was used to fit the experimental data. The activation energy was found to be 19.2 kcal/mol. The reaction was carried out without any solvent in order to make the process cleaner and greener. Copyright 2009 Society of Chemical Industry [source]


    A remarkable difference in the deprotonation steps of the Friedel,Crafts acylation and alkylation reactions

    JOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 11 2009
    Shinichi Yamabe
    Abstract Friedel,Crafts acylation and alkylation reactions were investigated using density functional theory calculations. The reaction systems studied were (benzene,+,acetyl chloride,+,Al2Cl6 (or AlCl3)) and (benzene,+,2-chloropropane,+,Al2Cl6). In the acylation reaction, the acylium ion intermediate is reached either via a MeC(Cl)OAl2Cl6 complex or via direct Cl transfer: MeC(O)ClAl2Cl6,,,MeCO,+Al2Cl. The ion adds to benzene electrophilically to form a Wheland intermediate containing a strong CHCl hydrogen bond, which leads to deprotonation and the subsequent formation of acetophenone. The resulting HClAl2Cl6 fragment is subjected to a nucleophilic attack by the carbonyl oxygen of the acetophenone, and recovery of the Al2Cl6 bridge is unlikely. Attack of the Al2Cl6 moiety by MeC(Cl)O gives the complex MeC(Cl)O,AlCl3, whose reactivity toward acylation is similar to that of the MeC(Cl)O,Al2Cl6 complex. In the alkylation reaction, deprotonation does not take place, but rather a [1,2] H-shift from the Wheland intermediate. The resulting , -protonated cumene undergoes deprotonation, with subsequent recovery of the Al2Cl6 bridge. In addition, the Al2Cl6 -catalyzed isomerization of the n -propyl to the isopropyl cation was found to be a dyotropic shift. Copyright 2009 John Wiley & Sons, Ltd. [source]


    Synthesis, characterization, and antimicrobial activity of some novel poly(ether ketone)s

    JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 15 2003
    Samir A. Patel
    Abstract Low molecular weight poly(ether ketone)s were synthesized from phenol, 1,4-phenylenedioxy diacetylchloride, chloroacetylchloride, and dichloroalkanes [1,2-dichloroethane and dichloromethane] by a Friedel,Crafts reaction with anhydrous aluminum chloride as a catalyst and carbon disulfide as a solvent. The conditions for the preparation of the poly(ether ketone)s and the chlorine contents obtained with the Carius method were examined, and a reaction scheme for each resin was established. The molecular weights and polydispersities of the resins were obtained by gel permeation chromatography. The polyketones were characterized by IR spectroscopy. The characteristic frequencies due to different functional groups were assigned. The thermal properties of the resins were studied with thermogravimetry and differential scanning calorimetry. The characteristic temperatures of thermal degradation for the poly(ether ketone)s were evaluated with thermogravimetric analysis. The kinetic parameters for the decomposition reactions of the resins were obtained with Broido and Doyle's method, and the heats of fusion were obtained from differential scanning calorimetry thermograms. The polyketones were thermally stable up to 200 C. All the polyketones were tested for their microbial properties against bacteria, fungi, and yeast. The effect of poly(ether ketone)s on the growth of these microorganisms was investigated, and the polyketones were found to inhibit the growth of the microorganisms to a considerable extent. 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2335,2344, 2003 [source]


    A New Synthetic Method for the Preparation of Star-Shaped Polyisobutylene with Hyperbranched Polystyrene Core

    MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 13 2007
    Gergely Kali
    Abstract Friedel,Crafts self-grafting of polystyrene (PSt) under quasiliving carbocationic polymerization was utilized to develop a new rapid one-pot method for the preparation of star-shaped polyisobutylene (PIB). First, the polymerization of isobutylene led to PIB with predetermined molecular weight (,=,2,000) and narrow molecular weight distribution (,=,1.03). Then addition of relatively small amount of styrene after isobutylene consumption yielded PIB-PSt diblocks. Multiple alkylation of the resulting PSt segments by the polystyryl cations led to hyperbranched PSt cores coupling PIB chains to form a star polymer in short reaction time (within an hour) compared to reported methods. The formation of star polymers by this self-grafting mechanism was proved by gel permeation chromatography equipped with online viscosimeter and 1H NMR spectroscopy. [source]


    Synthesis of poly(aryl ether ketone)s containing diphenyl moieties by electrophilic Friedel,Crafts solution polycondensation

    POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 12 2009
    Mingzhong Cai
    Abstract A new monomer, 4,4,-bis(4-phenoxybenzoyl)diphenyl (BPOBDP), was prepared by Friedel,Crafts reaction of 4-bromobenzoyl chloride and diphenyl, followed by condensation with potassium phenoxide. Novel poly(ether ketone ketone) (PEKK)/poly(ether ketone diphenyl ketone ether ketone ketone) (PEKDKEKK) copolymers were synthesized by electrophilic Friedel,Crafts solution copolycondensation of isophthaloyl chloride (IPC) with a mixture of diphenyl ether (DPE) and BPOBDP, in the presence of anhydrous aluminum chloride and N -methyl-pyrrolidone (NMP) in 1,2-dichloroethane (DCE). The copolymers obtained were characterized by various analytical techniques such as FT-IR, DSC, TGA, and wide-angle X-ray diffraction (WAXD). The results showed that the resulting copolymers exhibited excellent thermal stability due to the existence of diphenyl moieties in the main chain. The glass transition temperatures are above 152C, the melting temperatures are above 276C, and the temperatures at a 5% weight loss are above 548C in nitrogen. The copolymers with 50,70,mol% BPOBDP had tensile strengths of 101.5,102.7,MPa, Young's moduli of 3.23,3.41,GPa, and elongations at break of 12,17%. All these copolymers were semicrystalline and insoluble in organic solvents. Copyright 2008 John Wiley & Sons, Ltd. [source]


    The derivation of twin laws in non-merohedric twins.

    ACTA CRYSTALLOGRAPHICA SECTION A, Issue 5 2006
    Application to the analysis of hybrid twins
    An algorithm is presented to derive the twin laws in non-merohedric twins through the systematic search for quasi-perpendicular lattice planes/directions. The twin lattice, i.e. the sublattice common to the whole crystalline edifice built by the twinned individuals, is based on a supercell of the individual defined by a pair of quasi-perpendicular lattice elements (hkl)/[uvw]. Starting from a (real or supposed) twin element, (hkl) or [uvw], the set of quasi-perpendicular lattice elements with user-defined limits on the twin index and obliquity is explored. The degree of lattice quasi-restoration is commonly measured by the classical twin index but in some cases, especially for large supercells, this index represents only a first approximation of the degree of lattice quasi-restoration, because more than one pair (hkl)/[uvw] may exist, and more than one concurrent sublattices of nodes, based on the same twin element, may be quasi-restored, although within different obliquities. These twins, whose existence has been recently recognized, are termed hybrid twins. In hybrid twins, the degree of lattice quasi-restoration is measured by the effective twin indexnE, a generalization of the classical twin index: in the limiting case of only one (quasi-)restored sublattice, the effective twin index and the classical twin index coincide. A number of examples previously reported simply as `non-Friedelian' twins (with a twin index higher than the empirical limit of 6 established by Friedel) are analysed and reinterpreted as hybrid twins. A Fortran program is made available, which derives the possible twin laws according to this algorithm and analyses the pseudosymmetry of the concurrent sublattices defined by each pair (hkl)/[uvw]. The occurrence of hybrid concurrent components in twinning does not affect the normal procedures of dealing with diffraction patterns of twinned crystals. [source]