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Aromatic Diamines (aromatic + diamine)
Kinds of Aromatic Diamines Selected AbstractsNickel(0)/N-Heterocyclic Carbene Complexes Catalyzed Arylation of Aromatic Diamines.CHEMINFORM, Issue 29 2006Sebastien Kuhl Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Nonisothermal cure kinetics of DGEBA with novel aromatic diamineJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2007M. Ghaemy Abstract The effect of the molar ratio of diglycidyl ether of a bisphenol-A based epoxy (DGEBA) and synthesized 4-phenyl-2,6-bis(4-aminophenyl)pyridine (PAP) as curing agent during nonisothermal cure reaction by the Kissinger, Ozawa, and isoconversional equations was studied. The cure mechanism was studied by FTIR analysis. Kinetic analysis of the curing reaction of DGEBA at two different concentrations (42 and 32 phr) of the curing agent was studied by using DSC analysis. With an increasing PAP content, the pre-exponential factor increased by increasing collision probability between epoxide and primary or secondary amine groups in noncataltyic or catalytic modes. The activation energy also increased because of the increasing content of crosslink density. The activation energies obtained from three equations were in good agreement. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3076,3083, 2007. [source] Facile, one-pot synthesis of aromatic diamine-based phosphinated benzoxazines and their flame-retardant thermosetsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 20 2010Ching Hsuan Lin Abstract Three aromatic diamine-based, phosphinated benzoxazines (7,9) were prepared from three typical aromatic diamines,4,4,-diamino diphenyl methane (1), 4,4,-diamino diphenyl sulfone (2), and 4,4,-diamino diphenyl ether (3) by a one-pot procedure. To clarify the reaction mechanism, a two-pot procedure was applied, in which the reaction intermediates (4,6) were isolated for characterization. The structures of intermediates and benzoxazines were confirmed by high resolution mass, IR, and 1D and 2D-NMR spectra. In addition to self-polymerization, (7,9) were copolymerized with cresol novolac epoxy (CNE). After curing, the homopolymers of P(7,9) are brittle while the copolymers of (7,9)/CNE are tough. Dynamic mechanical analysis shows the Tgs of (7,9)/CNE copolymers are 187, 190, and 171 °C, respectively. Thermal mechanical analysis shows the CTEs of (7,9)/CNE copolymers are 46, 38, and 46 ppm, respectively. All the (7,9)/CNE copolymers belong to an UL-94 V-0 grade, demonstrating good flame retardancy. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010 [source] Sulfonated naphthalene dianhydride based polyimide copolymers for proton-exchange-membrane fuel cells.JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 4 2004Abstract A novel sulfonated diamine, 3,3,-disulfonic acid-bis[4-(3-aminophenoxy)phenyl]sulfone (SA-DADPS), was prepared from m -aminophenol and disodium-3,3,-disulfonate-4,4,-dichlorodiphenylsulfone. The conditions necessary to synthesize and purify SA-DADPS in high yields were investigated in some detail. This disulfonated aromatic diamine, containing ether and sulfone linkages, was used to prepare N -methyl-2-pyrrolidinone-soluble, six-membered ring polyimide copolymers containing pendent sulfonic acid groups by a catalyzed one-step high-temperature polycondensation in m -cresol. These materials showed much improved hydrolytic stability with respect to phthalimides. High-molecular-weight film-forming statistical copolymers with controlled degrees of disulfonation were prepared through variations in the stoichiometric ratio of disulfonated diamine (SA-DADPS) in its soluble triethylamine salt form to several unsulfonated diamines. Three unsulfonated diamines, bis[4-(3-aminophenoxy)phenyl] sulfone, 4,4,-oxydianiline, and 1,3-phenylenediamine, were used to prepare the copolymers. The characterization of the copolymers by 1H NMR, Fourier transform infrared, ion-exchange capacity, and thermogravimetric analysis demonstrated that SA-DADPS was quantitatively incorporated into the copolymers. Solution-cast films of the sulfonated copolymers were prepared and afforded tough, ductile membranes with high glass-transition temperatures. Methods were developed to acidify the triethylammonium salt membranes into their disulfonic acid form, this being necessary for proton conduction in a fuel cell. The synthesis and characterization of these materials are described in this article. Future articles will describe the performance of these copolymers as proton-exchange membranes in hydrogen/air and direct methanol fuel cells. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 862,874, 2004 [source] Synthesis and characterization of novel soluble triphenylamine-containing aromatic polyamides based on N,N,-bis(4-aminophenyl)- N,N,-diphenyl-1,4-phenylenediamineJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 16 2002Guey-Sheng Liou Abstract A new triphenylamine-containing aromatic diamine, N, N,-bis(4-aminophenyl)- N, N,-diphenyl-1,4-phenylenediamine, was prepared by the condensation of N,N,-diphenyl-1,4-phenylenediamine with 4-fluoronitrobenzene, followed by catalytic reduction. A series of novel aromatic polyamides with triphenylamine units were prepared from the diamine and various aromatic dicarboxylic acids or their diacid chlorides via the direct phosphorylation polycondensation or low-temperature solution polycondensation. All the polyamides were amorphous and readily soluble in many organic solvents such as N, N -dimethylacetamide and N -methyl-2-pyrrolidone. These polymers could be solution cast into transparent, tough, and flexible films with good mechanical properties. They had useful levels of thermal stability associated with relatively high glass-transition temperatures (257,287 °C), 10% weight-loss temperatures in excess of 550 °C, and char yields at 800 °C in nitrogen higher than 72%. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2810,2818, 2002 [source] Novel Soluble Polyimide Containing 4- tert- Butyltoluene Moiety: Synthesis and CharacterizationCHINESE JOURNAL OF CHEMISTRY, Issue 11 2009Chenyi Wang Abstract Based on the synthesis of a rigid aromatic diamine, ,,, -bis(4-aminophenyl)-4-(t- butyl)toluene (1), a novel polyimide (PI) 3 was prepared from this diamine monomer and 4,4,-oxydiphthalic dianhydride via a one-step high-temperature polycondensation. FT-IR, 1H NMR and elemental analysis were used to investigate the chemical structures of 1 and 3. The results confirmed that they agreed with the proposed structures for both 1 and 3 completely. The obtained PI 3 showed excellent solubility in most common solvents such as N -methyl-2-pyrrolidinone, N,N -dimethylacetamide, N,N -dimethylformamide, chloroform, dichloromethane and tetrahydrofuran. The resulting strong and flexible film exhibited high thermal stability with the glass transition temperature at 317°C and the temperature at 10% weight loss beyond 519°C in both air and nitrogen atmospheres. Moreover, the film also showed high optical transparency, low dielectric constant (3.13 at 1 MHz), low water absorption (0.40%) and hydrophobic character. [source] Poly(urethanes) containing silarylene and/or germarylene unitsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2008C. A. Terraza Abstract A series of 10 poly(urethanes) were synthesized by solution polymerization from bis(chloroformates) and aromatic diamines, containing both silicon or germanium as central atom. So, the polymers prepared contain two silicon atoms or two germanium atoms exclusively or combinations of both. Me, Et, and Ph groups were bonded to the central atoms according to the nature of the monomers employed. Poly(urethanes) were characterized by FTIR, 1H, 13C, and 29Si NMR spectroscopy and the results agreed with the proposed structures. Additionally, intrinsic viscosity values were established in DMSO solutions and thermal analyses were developed. In all cases, thermostable oligomers were obtained, which showed a degradation process beginning at ,240,260°C. Polymers showed a thermal dependence with the nature of the heteroatom employed. Thus, in general, when germanium was used as central atom, the thermal stability was higher than the polymers containing silicon which agrees with the lower polarity and higher energy of the CGe bond in comparison with the CSi one. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008. [source] Facile, one-pot synthesis of aromatic diamine-based phosphinated benzoxazines and their flame-retardant thermosetsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 20 2010Ching Hsuan Lin Abstract Three aromatic diamine-based, phosphinated benzoxazines (7,9) were prepared from three typical aromatic diamines,4,4,-diamino diphenyl methane (1), 4,4,-diamino diphenyl sulfone (2), and 4,4,-diamino diphenyl ether (3) by a one-pot procedure. To clarify the reaction mechanism, a two-pot procedure was applied, in which the reaction intermediates (4,6) were isolated for characterization. The structures of intermediates and benzoxazines were confirmed by high resolution mass, IR, and 1D and 2D-NMR spectra. In addition to self-polymerization, (7,9) were copolymerized with cresol novolac epoxy (CNE). After curing, the homopolymers of P(7,9) are brittle while the copolymers of (7,9)/CNE are tough. Dynamic mechanical analysis shows the Tgs of (7,9)/CNE copolymers are 187, 190, and 171 °C, respectively. Thermal mechanical analysis shows the CTEs of (7,9)/CNE copolymers are 46, 38, and 46 ppm, respectively. All the (7,9)/CNE copolymers belong to an UL-94 V-0 grade, demonstrating good flame retardancy. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010 [source] Copoly(peryleneimide)s containing 1,3,4-oxadiazole rings: Synthesis and propertiesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 19 2010Radu-Dan Rusu Abstract New copolyimides containing perylenediimide, oxadiazole and hexafluoroisopropylidene moieties were prepared by one-step polycondensation reaction in solution at high temperature of aromatic diamines containing preformed oxadiazole ring with a mixture of a dianhydride having a perylene ring and another dianhydride with hexafluoroisopropylidene unit. The thermal stability and glass transition temperatures of these copolyimides were measured and compared with those of related polyimides. The solid polymers were also studied by polarized light microscopy and X-ray diffraction which revealed a semicrystalline state consisting of face-to-face arranged columns of perylenediimide units. The film-forming ability and properties of the resulting thin films were investigated by using atom force microscopy and scanning electron microscopy which showed that the films were organized into self-assembled rod-like structures. The UV-Vis and photoluminescence properties in solution and in solid state were also investigated. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 4230,4242, 2010 [source] Condensation routes to polyaniline and its analogsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 21 2007H. K. Hall Abstract To obtain polyanilines which are more structurally perfect than those obtainable by the oxidation of anilines, polycondensation procedures were investigated. Model reactions gave extensive information about yields and about the physical properties of the putative structural polymer units. Condensation of anthraquinones with aromatic diamines using titanium tetrachloride and the unique base, 1,4-diazabicyclo-[2.2.2]-octane Dabco, gave high molecular weight orange polyquinonimines. Alkoxy groups on the anthraquinone ring aided solubility and molecular weight, and appropriately positioned alkoxy groups afforded stereoregular polymers. A bisthiophene benzoquinone also polymerized successfully. Application of the same procedure to 2,5-dimethyl- p -benzoquinone gave stereoregular poly(arylene benzoquinonimines), close analogs of pernigrani line. The factors causing problems in achieving high yields and high molecular weight were identified. Recent synthetic developments in this field are discussed. Reduction of the obtained polyquinonimines proceeded smoothly to the leucoemeraldine analogs. Unlike the results from pernigraniline obtained by oxidative polymerization, no evidence for the formation of the electrically conductive emeraldine form was obtained. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4751,4763, 2007 [source] Synthesis and properties of poly(amic acid)s and polyimides based on 2,2,,6,6,-biphenyltetracarboxylic dianhydrideJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 21 2006Katsuya Sakayori Abstract Poly(amic acid)s (PAAs) having the high solution stability and transmittance at 365 nm for photosensitive polyimides have been developed. PAAs with a twisted conformation in the main chains were prepared from 2,2,,6,6,-biphenyltetracarboxylic dianhydride (2,2,,6,6,-BPDA) and aromatic diamines. Imidization of PAAs was achieved by chemical treatment using trifluoroacetic anhydride. Among them, the PAA derived from 2,2,,6,6,-BPDA and 4,4,-(1,3-phenylenedioxy)dianiline was converted to the polyimide by thermal treatment. The heating at 300 °C under nitrogen did not complete thermal imidization of PAAs having glass-transition temperatures (Tg)s higher than 300 °C to the corresponding PIs. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6385,6393, 2006 [source] Polyimides based on new diamines having pendant imide groupsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 24 2005Hans R. Kricheldorf Abstract New aromatic diamines were prepared in two steps from 4,5-dichlorophthalic anhydride and primary amines. The resulting 4,5-dichlorophthalimide was reacted with 4-mercaptoaniline, so that the chloroatoms were substituted by the mercapto groups (via the sulfide anions). The new diamines were polycondensed either with the diphenyl ether 3,3,,4,4,-tetracarboxylic anhydride or with bicyclooctane tetracarboxylic anhydride. These polycondensations were conducted in boiling m -cresol with azeotropic removal of water. The isolated polyimides were characterized by viscosity measurement, IR-spectroscopy, elemental analyses, and MALDI-TOF mass spectrometry. The mass spectra evidenced a high content of cyclic polyimides, indicating nearly perfect reaction conditions. The mass spectra also proved the formation of copolymers containing one diamine with a trialkylamine group in the side chain. High glass transition temperatures but a low crystallization tendency were found by DSC measurements. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 6272,6281, 2005 [source] Synthesis and properties of novel soluble polyamides having ether linkages and laterally attached p -terphenyl unitsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 16 2004Sheng-Huei Hsiao Abstract A new ether-bridged aromatic dicarboxylic acid, 2,,5,-bis(4-carboxyphenoxy)- p -terphenyl (3), was synthesized by the aromatic fluoro-displacement reaction of p -fluorobenzonitrile with 2,,5,-dihydroxy- p -terphenyl in the presence of potassium carbonate, followed by alkaline hydrolysis. A set of new aromatic polyamides containing ether and laterally attached p -terphenyl units was synthesized by the direct phosphorylation polycondensation of diacid 3 with various aromatic diamines. The polymers were produced with high yields and moderately high inherent viscosities (0.44,0.79 dL/g). The polyamides derived from 3 and rigid diamines, such as p -phenylenediamine and benzidine, and a structurally analogous diamine, 2,,5,-bis(4-aminophenoxy)- p -terphenyl, were semicrystalline and insoluble in organic solvents. The other polyamides were amorphous and organosoluble and could afford flexible and tough films via solution casting. These films exhibited good mechanical properties, with tensile strengths of 91,108 MPa, elongations to break of 6,17%, and initial moduli of 1.95,2.43 GPa. These polyamides showed glass-transition temperatures between 193 and 252 °C. Most of the polymers did not show significant weight loss before 450 °C, as revealed by thermogravimetric analysis in nitrogen or in air. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4056,4062, 2004 [source] New liquid-crystalline thermosets from liquid-crystalline bisazomethynic epoxy resins with naphthylene disruptors in the central coreJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 10 2003P. Castell Abstract We synthesized novel epoxy-terminated monomers on the basis of imine groups with spacers of different lengths between mesogens and reactive groups and examined their mesogenic properties. Their reaction with primary aromatic diamines and tertiary amines was carried out to investigate the formation of liquid-crystalline thermosets. We explored how the curing conditions and the structures of the monomers and amines affected the formation of ordered networks. The special symmetry of a 1,5-disubstituted naphthalene unit in the central core led to nematic mesophases in the pure liquid-crystalline epoxy resins, and thermosets with locked nematic textures were obtained in all cases, regardless of the length of the spacer. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1536,1544, 2003 [source] Synthesis and characterization of aromatic polyamides containing alkylphthalimido pendent groupsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 21 2002E. Ferrero Abstract A series of polyisophthalamides containing pendent phthalimido groups and flexible side spacers were prepared from four novel diacids and three commercial aromatic diamines. These polyamides were prepared in high yields and with high molecular weights by direct polycondensation with triphenyl phosphite and pyridine as condensing agents. The weight-average and number-average molecular weights, measured by gel permeation chromatography, were 70,000,137,000 and 47,000,86,000 g/mol, respectively. The novel polyamides were amorphous and readily soluble and showed glass-transition temperatures of 150,240 °C, as measured by differential scanning calorimetry. Thermogravimetric analysis showed that the 10% weight-loss temperatures in nitrogen were 355,430 °C, a significant improvement in thermal stability having been observed with the increase in the side-chain length. A theoretical quantum mechanical study was successfully carried out to explain these results. Flexible and tough films, cast from polymer solutions, showed tensile strengths of 50,125 MPa. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3711,3724, 2002 [source] Synthesis and properties of organosoluble poly(amide imide imide)s based on tetraimide dicarboxylic acid condensed from 4,4,-(hexafluoroisopropylidene)diphthalic anhydride, 4,4,-oxydianiline, and trimellitic anhydride and various aromatic diaminesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 8 2002Chin-Ping Yang Abstract A novel tetraimide dicarboxylic acid was synthesized with the ring-opening addition of 4,4,-(hexafluoroisopropylidene)diphthalic anhydride, 4,4,-oxydianiline, and trimellitic anhydride in a 1/2/2 molar ratio in N -methyl-2-pyrrolidone followed by azeotropic condensation to tetraimide dicarboxylic acid. A series of poly(amide imide imide)s (PAIIs) with inherent viscosities of 0.8,1.1 dL/g were prepared from tetraimide dicarboxylic acid with various aromatic diamines by direct polycondensation. Most of the PAIIs were readily soluble in a variety of amide polar solvents and even in less polar m -cresol and pyridine. Solvent-cast films had tensile strengths ranging from 99 to 106 MPa, elongations at break ranging from 8 to 13%, and initial moduli ranging from 2.0 to 2.3 GPa. The glass-transition temperatures of these PAIIs were recorded at 244,276 °C. They had 10% weight losses at temperatures above 520 °C in air or nitrogen atmospheres. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1092,1102, 2002 [source] Organosoluble and transparent polyimides derived from alicyclic dianhydride and aromatic diaminesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 1 2002J. G. Liu Abstract Organosoluble polyimides were synthesized with the alicyclic dianhydride 1,8-dimethylbicyclo[2,2,2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride and aromatic diamines. The polyimides possessed good solubility both in strong dipolar solvents and in common solvents; the thermal decomposition temperature of the polyimides exceeded 420 °C. Strong and flexible films of the polyimides, with the cutoff of ultraviolet,visible absorption lower than 310,320 nm, exhibited good features as the alignment layers for nematic liquid crystals with pretilt angles of 1.5,2.9°. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 110,119, 2002 [source] 15N NMR spectroscopy as a method for comparing the rates of imidization of several diamines,POLYMER COMPOSITES, Issue 6 2006James C. Johnston The relative rates of the conversion of amide-acid to imide were measured for a series or aromatic diamines that have been identified as potential replacements for 4,4,-methylene dianiline (MDA) in high-temperature polyimides and polymer composites. These rates were compared with the 15N NMR resonances of the unreacted amines. The initial rates of imidization track with the difference in chemical shift between the amine nitrogens in MDA and those in the subject diamines. This comparison demonstrated that 15N NMR spectroscopy is appropriate for the rapid screening of candidate diamines to determine their reactivity relative to MDA, and can serve to provide guidance to the process of creating the time,temperature profiles used in processing these materials into polymer matrix composites. POLYM. COMPOS. 27:723,729, 2006. © 2006 Society of Plastics Engineers [source] Synthesis and characterization of aromatic/cycloaliphatic poly(amide- imide-imide)s from bis(4-amino- 3,5-dimethylphenyl) cycloalkane derivativesPOLYMER INTERNATIONAL, Issue 8 2007Bhuvana Sowrirajalu Abstract A series of novel aromatic diamines containing cycloaliphatic moieties was synthesized by the reaction of cycloalkanones like cyclohexanone and cycloheptanone with 2,6-dimethylaniline. The tetrimide diacid was synthesized using the prepared diamine with 3,3,,4,4,-benzophenonetetracarboxylic acid dianhydride/pyromellitic dianhydride and p -aminobenzoic acid. The polymers were prepared by treating the tetrimide diacid with different aromatic diamines. The structures of the monomers and polymers were identified using elemental analysis and Fourier transform infrared, 1H NMR and 13C NMR spectroscopy. The polymers show excellent solubility. The polymers are amorphous and have high optical transparency. They also show good thermal stability and their Tg value is found to be in the range 268,305 °C. Copyright © 2007 Society of Chemical Industry [source] Synthesis and properties of new aromatic polyimides based on 2,2,-dibromo-4,4,,5,5,-benzophenone tetracarboxylic dianhydridePOLYMER INTERNATIONAL, Issue 8 2004Ahmad Banihashemi Abstract New polyimides with enhanced thermal stability and high solubility were synthesized in common organic solvents from a new dianhydride, 2,2,-dibromo-4,4,,5,5,-benzophenone tetracarboxylic dianhydride (DBBTDA). DBBTDA was used as monomer to synthesize polyimides by using various aromatic diamines. The polymers were characterized by IR and NMR spectroscopy and elemental analysis. These polyimides had good inherent viscosities in N -methyl-2-pyrrolidinone (NMP) and also high solubility and excellent thermo-oxidative stability, with 5 % weight loss in the range 433 to 597 °C. Copyright © 2004 Society of Chemical Industry [source] Synthesis and characterization of novel aromatic poly(amide-imide)s derived from 2,2,-bis(4-trimellitimidophenoxy)biphenyl or 2,2,-bis(4-trimellitimidophenoxy)-1,1,-binaphthyl and various aromatic diaminesPOLYMER INTERNATIONAL, Issue 7 2003Ahmad Banihashemi Abstract New aromatic diimide-dicarboxylic acids having kinked and cranked structures, 2,2,-bis(4-trimellitimidophenoxy)biphenyl (2a) and 2,2,-bis(4-trimellitimidophenoxy)-1,1,-binaphthyl (2b), were synthesized by the reaction of trimellitic anhydride with 2,2,-bis(4-aminophenoxy)biphenyl (1a) and 2,2,-bis(4-aminophenoxy)-1,1,-binaphthyl (1b), respectively. Compounds 2a and 2b were characterized by FT-IR and NMR spectroscopy and elemental analyses. Then, a series of novel aromatic poly(amide-imide)s were prepared by the phosphorylation polycondensation of the synthesized monomers with various aromatic diamines. Owing to structural similarity, and a comparison of the characterization data, a model compound was synthesized by the reaction of 2b with aniline. The resulting polymers with inherent viscosities of 0.58,0.97 dl g,1 were obtained in high yield. The polymers were fully characterized by FT-IR and NMR spectroscopy. The ultraviolet ,max values of the poly(amide-imide)s were also determined. The polymers were readily soluble in polar aprotic solvents. They exhibited excellent thermal stabilities and had 10% weight loss at temperatures above 500 °C under a nitrogen atmosphere. Copyright © 2003 Society of Chemical Industry [source] Selective Iridium-Catalyzed Alkylation of (Hetero)Aromatic Amines and Diamines with Alcohols under Mild Reaction ConditionsCHEMISTRY - A EUROPEAN JOURNAL, Issue 15 2009Benoît Blank Abstract Selective amine alkylation: A P,N-ligand-stabilized iridium complex has been used as an efficient catalyst for the alkylation of (hetero)aromatic amines with alcohols at mild reaction temperatures and catalyst loadings as low as 0.1,mol,% Ir (see scheme). The excellent selectivity of the catalyst for monoalkylation of the amine function has also been exploited for the N,N,-dialkylation of diamines in both symmetric and nonsymmetric fashions. A P,N-ligand-coordinated iridium complex has been employed as an efficient catalyst for the selective monoalkylation of (hetero)aromatic amines with alcohols. A significant improvement of this alkylation method has been achieved, such that it can be performed at a temperature of 70,°C and with catalyst loadings as low as 0.1,mol,% Ir, while still affording excellent yields of secondary amines. Furthermore, the high selectivity of this catalyst for the monoalkylation of aromatic amino functions has been successfully exploited for the alkylation of diamines in both symmetric and nonsymmetric fashions, providing a novel and very efficient synthetic tool for the preparation of N,N,-dialkylated aromatic diamines. Ein P,N-Ligand-koordinierter Iridiumkomplex wird als ein effizienter Katalysator für die selektive Monoalkylierung von (hetero)aromatischen Aminen mit Alkoholen beschrieben. Eine signifikante Verbesserung dieser Alkylierungsmethode wurde erreicht. Bei Temperaturen von 70,°C und mit Katalysatorbeladungen von bis zu 0.1,mol,% Ir konnten exzellente Ausbeuten für sekundäre Amine erhalten werden. Weiterhin konnte die hohe Selektivität des Katalysators hinsichtlich der Monoalkylierung von aromatischen Aminogruppen genutzt werden, um Diamine symmetrisch und unsymmetrisch zu alkylieren. Damit steht ein neues sehr effizientes Synthesewerkzeug zur Darstellung von N,N, -alkylierten aromatischen Diaminen zur Verfügung. [source] Self-Assembly of Two-Component Gels: Stoichiometric Control and Component SelectionCHEMISTRY - A EUROPEAN JOURNAL, Issue 2 2009Andrew Abstract Two-component systems capable of self-assembling into soft gel-phase materials are of considerable interest due to their tunability and versatility. This paper investigates two-component gels based on a combination of a L -lysine-based dendron and a rigid diamine spacer (1,4-diaminobenzene or 1,4-diaminocyclohexane). The networked gelator was investigated using thermal measurements, circular dichroism, NMR spectroscopy and small angle neutron scattering (SANS) giving insight into the macroscopic properties, nanostructure and molecular-scale organisation. Surprisingly, all of these techniques confirmed that irrespective of the molar ratio of the components employed, the "solid-like" gel network always consisted of a 1:1 mixture of dendron/diamine. Additionally, the gel network was able to tolerate a significant excess of diamine in the "liquid-like" phase before being disrupted. In the light of this observation, we investigated the ability of the gel network structure to evolve from mixtures of different aromatic diamines present in excess. We found that these two-component gels assembled in a component-selective manner, with the dendron preferentially recognising 1,4 - diaminobenzene (>70,%), when similar competitor diamines (1,2- and 1,3-diaminobenzene) are present. Furthermore, NMR relaxation measurements demonstrated that the gel based on 1,4-diaminobenzene was better able to form a selective ternary complex with pyrene than the gel based on 1,4-diaminocyclohexane, indicative of controlled and selective ,,, interactions within a three-component assembly. As such, the results in this paper demonstrate how component selection processes in two-component gel systems can control hierarchical self-assembly. [source] | |||||||||||||