Polyesters containing sulfur. V. Preparation and characterization of new polyester–sulfur compositions

New polyester–sulfur compositions with increased tensile strength were obtained by using new thiopolyesters crosslinkable with sulfur, derived from diphenylmethane-4,4′-di(methylthiopropionic acid) and ethanediol (E-P) or 2,2′-oxydiethanol (ODE-P). Such characteristics as hardness, tensile, thermomechanical, as well as some electrical properties were determined. The structure of these compositions was investigated by solid-state ¹³C-NMR spectroscopy. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 2231–2238, 1997     

Preparation and properties of polyesters from diphenylmethane-4,4′-di(methylthiopropionic acid) and aliphatic diols

The new linear polyesters containing sulfur in the main chain were obtained by melt polycondensation of diphenylmethane-4,4′-di(methylthiopropionic acid) with ethanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,2-propanediol, 1,3-butanediol, and 2,2′-oxydiethanol. Low-molecular weights, low-softening temperatures and, very good solubility in organic solvents are their characteristics. The structure of all polyesters was determined by elemental analysis, FT-IR and ¹H-NMR spectroscopy, and x-ray diffraction analysis. The thermal behavior of these polymers was examined by differential thermal analysis (DTA), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The kinetics of polyesters formation by uncatalyzed melt polycondensation was studied in a model system: diphenylmethane-4,4′-di(methylthiopropionic acid) and 1,4-butanediol or 2,2′-oxydiethanol at 150, 160, and 170°C. Reaction rate constants (k₃) and activation parameters (ΔG^≠, ΔH^≠, ΔS^≠) from carboxyl group loss were determined using classical kinetic methods. © 1997 John Wiley & Sons, Inc.     

Kondesationen mit hydrazin-N,N′-dicarbonsäurediamidin,XXIII [1] fluorierte β-diketone als reaktionspartner

Application of a 30% aqueous potassium carbonate solution for the condensation of 1,2-hydrazinedicaboxamidine with 1,1,1-trifluoro-2,4-pentanedione leads to the formation of 4,4′-dimethyl-6,6′-bis(trifluoromethyl)-2,2′-hydrazopyrimidine, with 1,1,1-trifluoro-2,4-hexanedione to 4,4′-diethyl-6,6′-bis-(trifluoromethyl)-2,2′-hydrazopyrimidine. 2-Guanidinoamino-4-methyl-6-trifluoromethylpyridine formed as an intermediate in this reacton may be isolated, while 4-ethyl-2-guanidinoamino-6-trifluoromethylpyrimidine undergoes cyclization to yield 2-amino-5-ethyl-7-trifluoromethyl-s-triazolo[1,5-a]pyrimidine.     

A new rigid benzene‐bridged macrotricyclic ligand

A macrotricyclic ligand composed of two benzene rings connected by four 2,2′‐oxydiphenoxide bridges ( 2 ) has been prepared by treating 1,2,4,5‐tetrakis[2‐(2‐hydroxyphenoxy)phenoxymethyl]benzene with 1,2,4,5‐tetrakis(bromomethyl)benzene in acetonitrile in the presence of potassium carbonate. Ligand 2 is of interest because of its similarity to macrocycle 1 which interacts strongly with cesium ions. The proposed more direct route of treating an excess of 2,2′‐oxydiphenol with 1,2,4,5‐tetrakis(bromomethyl)benzene to prepare 2 did not give the desired macrocycle but gave bis(tribenzo‐11‐crown‐3) ( 8 ). An X‐ray crystal structure study of 2 showed that the benzene rings which are linked by the four 2,2′‐oxydiphenoxide bridges are connected in a nonsymmetric pattern. The structure of 8 was also determined using X‐ray diffraction methods, and is reported.     

Controlled enzymatic degradation of poly(?-caprolactone)-based copolymers in the presence of porcine pancreatic lipase

Poly(?-caprolactone) (PCL) has been extensively studied for biomedical use due to its outstanding biocompatibility. Well-defined random and block copolymers based on PCL such as poly(?-caprolactone-r-2,2-dimethyltrimethylene carbonate) (PCD), poly[(?-caprolactone-r-2,2-dimethyltrimethylene carbonate)-b-PEG-b-(?-caprolactone-r-2,2-dimethyltrimethylene carbonate)] (PECD) and poly[MPEG-b-(?-caprolactone-r-2,2-dimethyltrimethylene carbonate)] (MPECD) containing 5.0-8.5 mol% 2,2-dimethyltrimethylene carbonate (DTC) and 15.9-18.3 mol% polyethylene glycol (PEG) or polyethylene glycol monomethyl ether (MPEG) have been synthesized by using lanthanum tris(2,6-di-tert-butyl-4-methylphenolate) as catalyst. Their crystallization properties, thermal behaviors, hydrophilicities and degradation properties depend on the tunable microstructures and morphologies. It is found for the first time that porcine pancreatic lipase (PP lipase) can effectively catalyze the degradation of PCD electrospun mats (EMs) with 92.0% weight loss within 7 days while it shows no detectable effect on PCL EMs. Surface erosion mechanism is proposed in the enzymatic degradation systems, and the high proportion of amorphous domain of PCD contributes to its fast degradation rate according to the degradation product analyses. The enzymatic degradation rates of PCD EMs with porous structures and huge surface areas are higher than those of compression molding films (CMFs). Introducing PEG segment improves the hydrophilicity of PCD but decreases the degradation rate. A PEG segment enrichment process on the surface is addressed, which prevents the contact of PP lipase with PCD segments in the PEG-involved electrospun fiber. PECD and MPECD exhibit different mechanical strengths and contact angles, but similar degradation profiles. This study provides a practical example for tunable biodegradation of polyesters by designing the materials' bulk structures and/or surface morphologies.     

9,9′‐spirobifluorene‐containing polycarbonates: Transparent polymers with high refractive index and low birefringence

Syntheses of 2,2′‐bisalcoholic group‐substituted 9,9′‐spirobifluorene monomers 2 were performed by the reaction of 2,2′‐dihydroxy‐9,9′‐spirobifluorene 2a with haloalcohols. Polycarbonates consisting of 9,9′‐spirobifluorene skeleton in the main chain (PC 4 ) were synthesized by the polycondensation of 2,2′‐bisalcoholic monomers 2 and triphosgene or diphenyl carbonate. PC 4 showed good thermal stability: the 5% weight loss temperature was over 330 °C under both nitrogen and air atmospheres. The glass transition temperature was in a range of 16–269 °C estimated by differential scanning calorimetry, depending on the flexibility of the alkylene or oxyethylene chains of 2 . PC 4 showed high solubility toward ordinary organic solvents such as CHCl₃, benzene, and THF, making possible the preparation of the flexible thin films. Very high refractive index in a range of 1.62–1.66 at 589 nm was observed although PC 4 consists only of C, H, and O atoms, whereas very low degree of birefringence was confirmed. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3658–3667, 2010     

Thermal degradation of a polyphenylimide-quinoxaline in air and under vacuum

Three samples of poly{2,2′-[N,N′-bis(1,4-phenylene)benzophenone-3,3′,4,4′-tetracarboxylimide-6,6′-bis(3-phenyl-quinoxaline)]} (PPIQ), were prepared, differing in molecular weights and polymer chain endings. Their thermal degradation in vacuo and in air was determined by isothermal weight loss measurements. As in the case of poly-[2,2′-(1,4-phenylene)-6,6′-bis(3-phenylquinoxaline)] (PPQ), the temperature coefficients of thermal degradation in air were independent of molecular weight. However, in contrast, the temperature coefficients were independent of the type of polymer endgroups. It is, therefore, concluded that, contrary to amino-terminated PPQ's, polymer chain-end unzipping of PPIQ is of minor importance during thermal-oxidative degradation.     

Hydrogen-bonded assemblies of a new polyoxometalate-based 3-D supramolecular architecture

A new hydrogen-bonded 3-D supramolecular architecture [Ni(2,2′-bpy)₃]_1.5[AsW^VI ₁₀W^V ₂O₄₀Ni(2,2′-bpy)₂(H₂O)]·0.5H₂O (2,2′-bpy?=?2,2′-bipyridine) (1) has been hydrothermally synthesized and characterized by single-crystal X-ray diffraction analysis, PXRD, elemental analysis, XPS, and IR spectrum. Compound 1 exhibits photocatalytic activity for methylene blue degradation under visible-light irradiation and shows good stability toward visible-light photocatalysis. Luminescence of 1 is also reported.     

Reactions of 2,2′,5′,2′-terfuran

Formylation of 2,2′,5′,2′-terfuran ( 1 ) with N-methylformanilide and phosphorus oxychloride gave 5-formyl-2,2′,5′,2′-terfuran ( 2 ) and 5,5′-diformyl-2,2′5′,2′-terfuran ( 3 ). Reduction of 2 and 3 afforded 5-hydroxymethyl-2,2′,5′,2′-terfuran ( 4 ) and 5,5′ dihydroxymethyl-2,2′,5′,2′-terfuran ( 5 ), respectively. Terfuran 1 reacted with phenylmagnesium bromide to give 5-(phenylhydroxymethyl)-2,2′,5′,2′-terfuran ( 6 ), and was carbonated to 5-carboxy 2,2′,5′,2′-terfuran ( 7 ) and 5,5′-dicarboxy-2,2′,5′,2′-terfuran ( 8 ). Bromination of 1 with N-bromosuccinimide gave 5,5′-dibromo 2,2′,5′,2′-terfuran ( 9 ).     

Novel type of heterogenized CuCl2 catalytic systems for oxidative carbonylation of methanol

A novel type of heterogenized CuCl₂ catalysts was designed for the oxidative carbonylation of methanol to dimethyl carbonate (DMC) taking account of the plausible reaction mechanism and intermediates. To prevent severe corrosion of the reaction equipment materials due to Cl^? while keeping the catalytic activity of the homogeneous CuCl₂ catalyst, we adopted, as supports (or ligands) of CuCl₂, four polymers, bearing a 2,2′-bipyridine (bpy) or pyridine (py) unit, namely, poly(2,2′-bipyridine-5,5′-diyl) (Pbpy), poly(pyridine-2,5-diyl) (Ppy), poly(N,N′-bisphenylene-2,2′-bipyridine-4,4′-dicarboxylic amide) (Bpya), and poly(4-methyl-4′-vinyl-2,2′-bipyridine) (Pvbpy), together with one chelate compound, 8-quinolinol. The catalytic activity, stability of heterogenized CuCl₂ and their corrosivities to stainless steels were examined in the liquid-phase reaction of the oxidative carbonylation of methanol. These polymer-supported catalysts showed considerable catalytic activity and stability for the DMC synthesis. In particular, the Pbpy-CuCl₂ and Ppy-CuCl₂ catalysts exhibited high DMC yields and selectivity comparable to those of the homogeneous CuCl₂ catalyst. This high activity appears to be associated with the presence of the π-conjugated system in the polymers, which affect the redox reactions of Cu involved in the catalytic reaction. All of the polymer-supported CuCl₂ catalysts could be easily recycled after filtration, and the initial catalytic activity was maintained after three times of use. The corrosive characters of the catalysts were closely related to CuCl₂ leaching from the supports, which reflects the ability of supports to coordinate Cu. These experimental results suggest that both the electronic structure and the coordination ability of the polymer supports are key factors for the development of an effective catalytic system.     

Thermal oxidative degradation of the functionally substituted 2,2′-dipyrrolylmethenes hydrobromides and difluoroborates

Thermal oxidative decomposition of samples of crystalline hydrobromide and borofluoride complexes (BODIPY) of a series of 2,2′-dipyrrolylmethenes (HL) was studied by means of thermogravimetry in an atmosphere of air oxygen. An increase in the degree and symmetry of substitution, aromaticity, and the length of the substituents in 4,4′-positions of the pyrrole ligand rings increases stability of the BODIPY-dyes to oxidative degradation. A comparative analysis of the influence of structural factors on the thermolability of hydrobromdes (HL·HBr), d-metal (ML₂) and boron(III) complexes with 2,2′-dipyrrolylmethenes was carried out.     

Cyclic and telechelic ladder polymers derived from tetrahydroxytetramethylspirobisindane and 1,4‐dicyanotetrafluorobenzene

5,5′,6,6′‐Tetrahydroxy‐3,3,3′,3′‐tetramethylspirobisindane was polycondensed with 1,4‐dicyanotetrafluorobenzene in four different solvents at 70 °C. In dimethylformamide, N‐methylpyrrolidone, and sulfolane exclusively, cyclic polymers were detectable by matrix‐assisted laser desorption/ionization time‐of‐flight (MALDI‐TOF) mass spectrometry up to masses around 13,000 Da. In dimethyl sulfoxide, linear byproducts were also found. Higher temperatures caused degradation reactions catalyzed by potassium carbonate. Polycondensations performed with the addition of 4‐tert‐butyl catechol or 2,2′‐dihydroxy binaphthyl yielded linear telechelic oligomers. Equimolar mixtures of linear and cyclic ladder polymers were examined by MALDI‐TOF mass spectra to determine how the end groups and the cyclic structure influenced the signal‐to‐noise ratio. The results suggested a preferential detection of the linear chains. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5344–5352, 2006     

Chromium(VI) oxide-mediated oxidation of polyalkyl-polypyridines to polypyridine-polycarboxylic acids with periodic acid

4,4′-Dicarboxy-2,2′-bipyridine was synthesized quantitatively by chromium(VI) oxide-mediated oxidation of 4,4′-dimethyl-2,2′-bipyridine or 4,4′-diethyl-2,2′-bipyridine with periodic acid as the terminal oxidant in sulfuric acid. 5,5′-Dicarboxy-2,2′-bipyridine and 6,6’-dicarboxy-2,2′-bipyridine were also synthesized by the method from the corresponding dimethyl bipyridines in excellent yields. 4,4′,4″-Tricarboxy-2,2′:6′,2″-terpyridine was obtained in 80% yield from 4,4′,4″-triethyl-2,2′:6′,2″-terpyridine, and 4,4′,4″,4′″-tetracarboxy-2,2′:6′,2″:6″,2′″-quaterpyridine was obtained in 72% yield from 4,4′,4″,4′″-tetraethyl-2,2′:6′,2″:6″,2′″-quaterpyridine by the same procedure.     

Preparation and characterization of aromatic copolyesters containing the o,o′-biphenylene ring system

Poly[oxy-2,2′-diphenyleneoxyisophthaloyl-b-oxy(2-methyl-1,3-phenylene)oxyterephthaloyl] I, poly[oxy-2,2′-diphenyleneoxyterephthaloyl-b-oxy(2-methyl-1,3-phenylene)oxyterephthaloyl] II, poly(oxy-2,2′-diphenyleneoxyisophthaloyl-b-oxy-2,2′-diphenyleneoxyterephthaloyl) III, poly[oxy-2,2′-diphenyleneoxyterephthaloyl-b-oxy(2-methyl-1,4-phenylene)oxyterephthaloyl] IV, poly[oxy2,2′-diphenyleneoxyterephthaloyl-b-oxy(2-chloro-1,4-phenylene)oxyterephthaloyl] V, poly[oxy-2,2′-diphenyleneoxyterephthaloyl-co-oxy(2-chloro-1,4-phenylene)oxyterephthaloyl] VI, and poly[oxy-2,2′-diphenyleneoxyterephthaloyl-co-oxy(2-methyl-1,4-phenylene)oxyterephthaloyl] VII have been synthesized and characterized. Random copolyester VI appears to form a birefringent fluid phase above the melting temperature.     

Die Synthese von Actinioerythrol,Violerythrin und anderen 2,2′-Dinor-carotinoiden

The Synthesis of Actinioerythrol, Violerythrin and other 2,2′-Dinor-carotenoids 2,2′-Dinor-carotenoids including the naturally occurring actinioerythrol ( 1 ) and the blue carotenoid violerythrin ( 2 ), as well as 2,2′-dinor-rhodoxanthin ( 25 ) and 2,2′-dinor-zeaxanthin ( 27 ) and others have been obtained by total synthesis.     

Synthesis and characterization of star oligo/poly(2,2‐dimethyltrimethylene carbonate)s containing cholic acid moieties

Star oligo/poly(2,2‐dimethyltrimethylene carbonate)s containing cholic acid moieties were synthesized through the ring‐opening polymerization of 2,2‐dimethyltrimethylene carbonate (DTC) initiated by cholic acid with hydroxyl groups. Through the control of the feed ratio of the initiator cholic acid to the monomer DTC, a series of star oligomers/polymers with different molecular weights were obtained. The star oligomers/polymers were characterized with Fourier transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, combined size exclusion chromatography/multi‐angle laser light scattering analysis, wide‐angle X‐ray scattering, polarizing light microscopy, and differential scanning calorimetry. Compared with linear poly(2,2‐dimethyltrimethylene carbonate), these star oligo/poly(2,2‐dimethyltrimethylene carbonate)s had much faster hydrolytic degradation rates. With one of the star oligomers/polymers, a microsphere drug‐delivery system of a submicrometer size was fabricated with a very convenient ultrasonic dispersion method that did not involve toxic organic solvents. The in vitro drug release was studied. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6688‐6696, 2006     

三亚甲基环碳酸酯及2,2-二甲基三亚甲基环碳酸酯开环均聚合*

生物降解聚合物聚三亚甲基环碳酸酯（PTMC）及聚2,2-二甲基三亚甲基环碳酸酯（PDTC）在药物控释载体及其它生物医学技术领域有着良好的应用前景。与脂肪族聚酯不同,PTMC、PDTC降解时,不会产生有害的酸性化合物。PTMC、PDTC主要由三亚甲基环碳酸酯（TMC）及2,2-二甲基三亚甲基环碳酸酯（DTC）开环均聚合制备。本文总结了催化TMC、DTC开环均聚合的不同催化剂及其聚合机理,综述了近年来国内外在TMC、DTC均聚合催化剂开发上的研究进展,并对生物相容性催化剂如稀土催化剂、Ca、Mg、Zn、Fe催化剂以及酶催化剂催化TMC、DTC开环聚合的优缺点进行了比较。     

Investigation of reactions of the organozinc reagents prepared from zinc and dialkyl dibromomalonates with the derivatives of 2-arylmethyleneindan-1,3-dione and 5-arylmethylene-2,2-dimethyl-1,3-dioxane-4,6-dione

Organozinc compounds prepared from dialkyl dibromomalonates and zinc react with 2-arylmethyl-eneindan-4,6-diones, 5-arylmethylene-2,2-dimethyl-1,3-dioxane-4,6-diones, as well as with 2-[4-(1,3-dioxoindan-2-ylidenemethyl)phenyl]methyleneindan-1,3-dione and 5-[4-(2,2-dimethyl-4,6-dioxo-1,3-dioxane-2-ylidenemethyl)phenyl]methylene-2,2-dimethyl-1,3-dioxane-4,6-diones to form dialkyl 3-aryl-1′3′-dioxaspiro(cyclopropane-2,2′-indan)-1,1-dicarboxylates, dimethyl 3-aryl-6,6-dimethyl-5,7-dioxa-4,8-dioxaspiro[2,5]octan-2,2-dicarboxylates, dialkyl 2-{4-[3,3-bis (alkoxycarbonyl)-1′,3′-dioxaspiro(cyclopropane-2,2′-indan)-1-yl]phenyl}-1′,3′-dioxaspiro[cyclopropane-2,2′-indan]-1,1-dicarboxylates, and dialkyl 2-{4-[2,2-bis(alkoxycarbonyl)-6,6′-dimethyl-4,8-dioxo-5,7-dioxaspiro[2,5]oct-1-yl]phenyl}-6,6-dimethyl-4,8-dioxo-5,7-dioxaspiro[2,5]octan-1,1-dicarboxylate respectively.     

Effects of linking groups in fluorinated aromatic polyamides

Based on dynamic thermogravimetric analysis (TGA) of fluorinated aromatic polyamides, we found that substituting terephthaloyl units for isophthaloyl units usually increased the thermal stability of the polymers. In contrast, the first steps of thermal degradation of poly(5,5′-sulfonyl-2,2′-difluoro-diphenyl terephthalamide) (2,2′-DIF-PSDPT) and poly(5,5′-sulfonyl-2,2′-difluorodphenyl isophthalamide)(2,2′-DIF-PSDPI) followed almost the same curve. This was attributed to the relative flexibility of the ? SO₂? group, and also to the activating effect on the dehydrofluorination reaction, which was believed to be the first step of the degradation of the ortho-fluorinated aromatic polyamides, , resulting in the formation of benzoxazole groups, , on the polymer backbone. With fluorinated aromatic polyamides having ortho fluorine to the amide nitrogen, the electron releasing ? CH₂? group deactivated the nucleophilic substitution of the dehydrofluorination reaction and the electron withdrawing group ? SO₂? activated the reaction, so that the onset degradation temperatures of the fluorinated aromatic units R in followed the order:      

Synthesis and characterization of lead(II) complexes with substituted 2,2′-bipyridines,trifluoroacetate, and furoyltrifluoroacetonate

Two substituted 2,2′-bipyridine lead(II) complexes, [Pb(5,5′-dm-2,2′-bpy)(tfac)₂] _n (1) (5,5′-dm-2,2′-bpy?=?5,5′-dimethyl-2,2′-bipyridine and tfac?=?trifluoroacetate) and [Pb₂(4,4′-dmo-2,2′-bpy)₂(ftfa)₄] (2) (4,4′-dmo-2,2′-bpy?=?4,4′-dimethoxy-2,2′-bipyridine and ftfa?=?furoyltrifluoroacetonate), have been synthesized and characterized by elemental analysis, IR, ¹H NMR, and ¹³C NMR spectroscopies, thermal behavior, and X-ray crystallography. Complexes 1 and 2 are 1D coordination polymer and dinuclear complex, respectively. The supramolecular features in these complexes are guided by weak directional intermolecular interactions.