Organosoluble and thermally stable polyimides derived from a new diamine containing bulky-flexible triaryl pyridine pendent group

A novel kind of aromatic diamine,N-(4-(4-(2,6-diphenyl pyridine-4-yl)phenoxy)phenyl)-3,5-diaminobezamide (DPDAB),was synthesized via aromatic nucleophilic substitution of 3,5-dinitrobenzoylchloride with 4-(4-(2,6- diphenylpyridine-4-yl)phenoxy)aniline(DPPA),followed by palladium-catalyzed hydrazine reduction.This monomer was used to prepare polyimides(PIs)based on reaction with several commerically avaiable tetracarboxylic dianhydrides such as pyromellatic dianhydride(PMDA),benzophenone tetracarboxylic acide dianhydride(BTDA)and bicycle[2.2.2]oct-7-enc- 2,3,5,6-tetracarboxylic dianhydride(BCDA).These PIs had inherent viscosity in the range of 0.34-0.76 dL/g and showed good solubility in various aprotic polar solvents.The glass-transition tempratures(T_gs)of the PIs were in the range of 184-302℃,and showed high thermal stability with 10%weight loss in the temperature range of 360-500℃under nitrogen atmosphere.     

New thermally stable polyesters based on 2,5-pyridinedicarbonyl dichloride and aromatic diols:Synthesis and characterization

Six new thermally stable polyesters(4a-f) were synthesized through the solution polycondensation reaction of 2,5-pyridine dicarbonyldichloride(2) with six aromatic diols in N,N'-dimethyl acetamide(DMAc) solution and in the presence of pyridine as a base.The polycondensation reactions produce a series of new polyesters(4a-f) in high yields,and inherent viscosity between 0.30 and 0.55 dL/g.The resulting polyesters were characterized by elemental analysis,viscosity measurements,thermal gravimetric analysis(...     

Synthesis and characterization of optically active poly(amide-imide)s containing photosensitive chalcone units in the main chain

<正>A series of new optically active poly(amide-imide)s were synthesized by direct polycondensation reaction of 4,4'-diaminochalcone with several N-trimellitylimido-L-amino acids using a tosyl chloride(TsCl),pyridine(Py) and dimethylformamide(DMF) system as condensing agent.The resulting thermally stable poly(amide-imide)s were obtained in good to high yields and inherent viscosities ranging between 0.35 dL/g and 0.58 dL/g and were characterized with FTIR, ~1H-NMR,CHN,Ultraviolet,TGA and DTG techniques.     

Synthesis of soluble and thermally stable polyimides from unsymmetrical diamine containing 2,4,5-triaryl imidazole pendent group

A novel unsymmetrical diamine monomer containing triaryl imidazole pendant group, 4-[4-(4,5-diphenyl-1H-imidazol-2-yl)phenoxy] benzene-1,3-diamine (DAI), was successfully synthesized via aromatic substitution reaction of 1-chloro-2,4-dinitrobenzene with 4-(4,5-diphenyl-1H-imidazol-2-yl)phenol, followed by palladium-catalyzed hydrazine reduction. The diamine monomer DAI polymerized with commercial available dianhydrides such as benzophenone tetracarboxylic dianhydride (BTDA), pyromellitic dianhydride (PMDA) and bicyclo[2.2.2]-oct-7-ene-2,3,5,6-tetracarboxylic dianhydride (BCDA) by using two step synthetic methods to obtain corresponding polyimides (PIs). PIs had inherent viscosity of 0.42-0.51 dL/g and exhibited excellent solubility in aprotic polar solvents such as N,N-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (NMP), N,N-dimethylformamide (DMF), pyridine and methyl sulfoxide (DMSO). PIs showed high glass transition temperatures between 230 and 320 °C, and they were fairly stable up to a temperature above 300 and 450 °C depending on the dianhydride monomer used for the PIs preparation.     

Synthesis of optically active oligomers consisting of chiral phosphorus atoms: capture of an intermediate between a polymer and a small molecule

We describe here the synthesis and properties of novel optically active oligophosphines. The effect of the number of chiral phosphorus atoms on thermal properties and conformations is documented. In this study, we captured an intermediate between a polymer and a small molecule. To the best of our knowledge, it is primarily observed that a small molecule transforms into a polymer via an amorphous small molecule during the process of the elongation of the oligomer main chain.     

Synthesis and characterization of optically active polymers containing azo groups and (l)-α-amino acid moieties

The paper discusses the synthesis of new optically active azo diacids starting from two activated azo diesters (diethyl azodicarboxylate and ethyl phenylazocarboxylate) and various (l)-α-amino acids as: (l)-alanine, (l)-leucine, (l)-cysteic acid monohydrate and (l)-cystine. New chiral polymers derived from some of synthesized monomers were obtained under mild reaction conditions by unconventional polycondensation methods. The structure of synthesized compounds has been spectroscopically confirmed and the solubility, optical activity and thermal properties of the obtained materials are reported. To estimate the molecular weights of new polymers the ¹H-NMR and viscometric data were used and obtained values were compared with those of the polymers with alike chain structure synthesized by similar procedures.     

Isolation, absolute configuration, and chiral crystallization of optically active seleninic acid

An optically pure seleninic acid was isolated as stable crystals for the first time by chiral crystallization. The relationship between the absolute configurations and the circular dichroism spectra of the enantiomers could be determined by X-ray crystallographic analysis.     

Novel optically active poly(amide-imide)s from N,N-(4,4-carbonyldiphthaloyl)-bis-l-phenylalanine diacid chloride and aromatic diamines by microwave irradiation

3,3^′,4,4^′-benzophenonetetracarboxylic dianhydride (4,4^′-carbonyldiphthalic anhydride) (1) was reacted with l-phenylalanine (2) in a mixture of acetic acid and pyridine (3:2) and the resulting imide-acid [N,N^′-(4,4^′-carbonyldiphthaloyl)-bis-l-phenylalanine diacid] (4) was obtained in high yield. The compound (4) was converted to the N,N^′-(4,4^′-carbonyldiphthaloyl)-bis-l-phenylalanine diacid chloride (5) by reaction with thionyl chloride. A new facile and rapid polycondensation reaction of this diacid chloride (5) with several aromatic diamines such as 4,4^′-diaminodiphenyl methane (6a), 2,4-diaminotoluene (6b), 4,4^′-sulfonyldianiline (6c), p-phenylenediamine (6d), 4,4^′-diaminodiphenylether (6e), m-phenylenediamine (6f), benzidine (6g) and 2,6-diaminopyridine (6h) was developed by using a domestic microwave oven in the presence of a small amount of a polar organic medium such as o-cresol. The polymerization reactions proceeded rapidly, compared with the conventional solution polycondensation, and was completed within 7 min, producing a series of optically active poly(amide-imide)s with high yield and inherent viscosity of 0.22-0.52 dl/g. All of the above polymers were fully characterized by IR, elemental analyses and specific rotation. Some structural characterization and physical properties of this optically active poly(amide-imide)s are reported.     

Use of ionic liquid and microwave irradiation as a convenient, rapid and eco-friendly method for synthesis of novel optically active and thermally stable aromatic polyamides containing N-phthaloyl-l-alanine pendent group

An efficient, fast and easy method for synthesis of new optically active and thermally stable aromatic polyamides (PAs) containing pendent phthalimide group and l-alanine flexible side spacer using room temperature ionic liquid (RTIL) by microwave irradiation has been investigated. The results found that RTIL efficiently absorb microwave energy, thus leading to a very high heating rate. All the PAs showed excellent solubility and readily dissolved in various organic solvents. Thermogravimetric analysis (TGA) exhibited that polymers were stable, with 10% weight loss recorded above 373 and 418 °C in the nitrogen atmosphere. In order to see the efficiency of microwave irradiation, this method was compared with polycondensation of the same monomers in RTILs using conventional heating.     

Synthesis and properties of novel diisocyanate based optically active polyimides

A new optically active diisocyanate was prepared from the reaction of l-leucine and pyromellitic dianhydride (PMDA) and subsequent transformation of intermediate imide-containing diacid to diisocyanate via Weinstock modification of Curtius rearrangement. Solution polycondensation reaction of the prepared diisocyanate with PMDA, 3,3,4,4-benzophenonetetracarboxylic dianhydride, and hexafluoroisopropylidene 2,2-bis(phthalic anhydride) resulted in the preparation of novel optically active polyimides. The optimal conditions for polyimidations (reaction duration and temperature programming) were obtained via study of the model compound. The monomer, model compound and polymers were characterized by FTIR, ¹HNMR, mass spectroscopy and elemental analysis and their optical and physical properties were studied as well.     

Synthesis of optically active polymers containing chiral phosphorus atoms in the main chain

We successfully synthesized optically active polymers by using a chiral bisphosphine, (S,S)‐1,2‐bis[boranato(t‐butyl)methylphosphino]ethane, as a key building block. Their structures were characterized with ¹H, ¹³C, and ³¹P NMR spectra. The obtained polymers exhibited different glass‐transition temperatures depending on the structure of each comonomer, whereas a model compound had a melting point. According to circular dichroism spectra, the difference in the stereochemistry of the comonomers yielded the different higher‐ordered structures of the polymers induced by chiral phosphine units. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 866–872, 2007     

Microwave-promoted synthesis of new optically active poly(ester-imide)s derived from N,N-(pyromellitoyl)-bis-l-leucine diacid chloride and aromatic diols

Pyromellitic dianhydride (benzene-1,2,4,5-tetracarboxylic dianhydride) (1) was reacted with l-leucine (2) in a mixture of acetic acid and pyridine (3:2) and the resulting imide-acid [N,N^′-(pyromellitoyl)-bis-l-leucine diacid] (4) was obtained in quantitative yield. The compound (4) was converted to the N,N^′-(pyromellitoyl)-bis-l-leucine diacid chloride (5) by reaction with thionyl chloride. A new facile and rapid polycondensation reaction of this diacid chloride (5) with several aromatic diols such as phenol phthalein (6a), bisphenol-A (6b), 4,4^′-hydroquinone (6c), 1,8-dihydroxyanthraquinone (6d), 1,5-dihydroxy naphthalene (6e), 4,4-dihydroxy biphenyl (6f), and 2,4-dihydroxyacetophenone (6g) was developed by using a domestic microwave oven in the presence of a small amount of a polar organic medium such as o-cresol. The polymerization reactions proceeded rapidly and are completed within 10 min, producing a series of optically active poly(ester-imide)s (PEIs) with good yield and moderate inherent viscosity of 0.10-0.27 dl/g. All of the above polymers were fully characterized by IR, elemental analyses and specific rotation. Some structural characterization and physical properties of these optically active PEIs are reported.     

Interfacial synthesis and properties of L-lysine-derived optically active poly(ester-imide)s

L-Lysine hydrochloride was transformed to ethyl L-lysine dihydrochloride.This salt was reacted with trimellitic anhydride to yield the corresponding diacid（1）.Intertacial polycondensation results novel poly（ester-imide）s(PEI_a-i).These polymers have inherent viscosities in the range of 0.23-0.47 dl g^-1,display optical activity,and are readily soluble in polar aprotic solvents.They start to decompose(T_10%) above 350℃and display glass-transition temperatures at 100.42-172.81℃.All of the above polymers were fully characterized by UV,FT-IR and ¹H NMR spectroscopy,elemental analysis,TGA,DSC,inherent viscosity measurement and specific rotation.     

Synthesis and characterization of optically active polyamides based on 2-(1,3-isoindolinedione-2-yl)glutaric acid by direct polycondensation

<正>Five new optically active polyamides(PAs) 6a-6e were prepared by direct polycondensation reaction of 2-(1,3- isoindolinedione-2-yl)-glutaric acid 4 as a new chiral diacid with various aromatic diamines 5a-5e in a medium consisting of triphenyl phosphite(TPP),calcium chloride,pyridine(Py) and N-methyl-2-pyrrolidone(NMP).The polycondensation reaction produced a series of polyamids 6a-6e in quantitative yields with inherent viscosities of 0.26-0.39 dL/g.The resulting polymers were fully characterized by means of ~1H-NMR,FT-IR spectroscopy,elemental analysis,inherent viscosity and specific rotation.Thermal properties of these polymers were investigated using thermal gravimetric analysis (TGA) and differential thermal gravimetry(DTG).Phthalimide rings as a bulky pendent group in the polymer chains disturb the interchain and intrachain interactions and make these PAs readily soluble in polar,aprotic solvents such as N,N-dimethyl acetamide(DMAc),N,N-dimethyl formamide(DMF),dimethyl sulfoxide(DMSO),N-methyl-2-pyrrolidone(NMP) and sulfuric acid.     

Synthesis and properties of thermally reversible polyesters

Thermally reversible polyesters were obtained by the ester formation reaction of thermoplastic polyesters with hydroxyl end groups and the diacid anhydride of tetra carboxylic acid as a thermally reversible chain extender. Typical example of the thermally reversible polyesters was obtained by the reaction of PBT (polyburylene terephthalate) and PMA (pyromellitic dianhydride). This material having twice as large molecular weight as the original PBT exhibited almost the same melt viscosity as the original. Also that thermally reversible chain extension reaction occurred without unfavorable side reaction such as cross-linking. This material shows both good processability and superior mechanical properties due to its thermally reversible characters.     

Microwave-assisted rapid synthesis of novel optically active poly(amide-imide)s containing hydantoins and thiohydantoins in main chain

Rapid and highly efficient synthesis of novel optically active poly(amide-imide)s (PAIs) 6(a-f) was achieved using microwave irradiation. These were made from the polycondensation reactions of 4,4^′-carbonyl-bis(phthaloyl-l-alanine) diacid chloride [N,N^′-(4,4^′-carbonyldiphthaloyl)] bisalanine diacid chloride 5 with six different derivatives of hydantoin and thiohydantoin compounds 4(a-f) in the presence of a small amount of a nonpolar organic medium that acts as a primary microwave absorber. Hydantoin and thiohydantoin derivatives 4(a-e) were synthesis from the reactions between benzil or benzil derivatives 3(a-e) with urea and thiourea. 5,5-Dimethylhydantoin 4f was synthesis from the reactions between acetone cyanohydrin 3f and ammonium carbonate. The polycondensation proceeded rapidly, and was completed within 10 min giving a series of PAIs with an inherent viscosity about 0.25-0.45 dL/g. The resulting PAIs 6(a-f) were obtained in a high yield and were optically active and thermally stable. All of the above compounds were fully characterized by means of Fourier transform infrared spectroscopy, elemental analyses, inherent viscosity (η_inh), solubility tests and specific rotation. Thermal properties of the PAIs 6(a-f) were investigated using thermal gravimetric analysis.     

Synthesis and properties of novel optically active polyimides

A facile synthesis of an optically active di‐isocyanate containing alkylene groups and a preformed imide structure is described. Polycondensation reactions of the prepared di‐isocyanate with pyromellitic dianhydride, benzophenone tetracarboxylic dianhydride, and hexafluoroisopropylidene diphthalic anhydride resulted in the preparation of optically active, thermally stable polyimides. The prepared monomer and polymers were characterized by conventional methods. Optical and physical properties of the polymers including thermal stability, thermal behavior, solution viscosity, and solubility behavior were studied. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 514–518, 2001     

Optically active ruthenium porphyrins: chiral recognition and asymmetric catalysis

The current applications of ruthenium porphyrins in stoichiometric and catalytic asymmetric reactions are reported. Chiral recognition of racemic phosphines, isocyanides and amino esters has been studied by ¹H-NMR. Experimental investigations of the oxidation mechanism of racemic phosphines and amino esters are described. The stereochemistry of catalytic asymmetric oxidation and cyclopropanation of olefins with optically active ruthenium porphyrins are also discussed.     

Eco-friendly fast synthesis and thermal degradation of optically active polyamides under microwave accelerating conditions

<正>An optically active bulky aromatic diacid chiral monomer,(2S)-4-[(4-methyl-2-phthalimidylpentanoyl-amino) benzoylamino]isophthalic acid(1),containing a rigid phthalimide and flexible L-leucine pendent group was synthesized in five steps.A fast and clean method for direct polyamidation reaction of monomer 1 with various aromatic diamines under microwave irradiation and conventional heating was performed.The polymerization reactions provided optically active polyamides with high yields and inherent viscosities in the range of 0.36-0.74 dL/g.Their thermal properties were evaluated by thermogravimetric analysis(TGA) and differential scanning calorimetry.TGA thermograms show that the polymers are thermally stable,10%weight loss temperatures are in excess of 385℃,and char yields at 800℃are higher than 56%.The data obtained from TGA were used to study the kinetics of thermal decomposition of the resulting polymers. The interpretation of kinetic parameters(E,ΔH,ΔS andΔG) of thermal decomposition stages was evaluated using Coats and Redfern equation.     

A practical synthesis of optically active aromatic epoxides via asymmetric transfer hydrogenation of α-chlorinated ketones with chiral rhodium-diamine catalyst

A practical method for the synthesis of optically active aromatic epoxides has been developed via the formation of optically active α-chlorinated alcohols and intramolecular etherification. Optically active alcohols with up to 99% ee can be obtained from the asymmetric reduction of aromatic ketones with a substrate/catalyst ratio of 1000-5000 using a formic acid/triethylamine mixture containing a well-defined chiral Rh complex, Cp*RhCl[(R,R)-Tsdpen]. The asymmetric reduction of α-chlorinated aromatic ketones with a chiral Rh catalyst is characterized by a rapid and carbonyl group-selective transformation because of the coordinatively saturated nature of diamine-based Cp*Rh(III) hydride complexes. The outcome of the reduction is significantly influenced by the structures of the ketonic substrates as well as the hydrogen source such as formic acid or 2-propanol. Commercially available reagents and solvents can be used in this reaction without special purification. This epoxide synthetic process in either a one- or two-pot procedure is practical and particularly useful for the large-scale production of optically active styrene oxides from α-chlorinated ketones.