Polyesters,polyurethanes and epoxy resins derived from 2,2′-(1,4-phenylenedivinylene)bis-8-hydroxyquinaldine and 6-(4-hydroxystyryl)-3-hydroxypyridine

New polyesters and polyurethanes as well as diepoxides bearing styrylpyridine segments were prepared utilizing 2,2′-(1,4-phenylenedivinylene)bis-8-hydroxyquinaldine (PBHQ) and 6-(4-hydroxystyryl)-3-hydroxypyridine (HSHP) as starting materials. The polyesters were prepared by reacting PBHQ or HSHP with terephthaloyl dichloride in the presence of an acid acceptor utilizing the solution polycondensation method. The polyurethanes were prepared from the reactions of PBHQ and HSHP with tolylene diisocyanate and methylenebis(4-phenylisocyanate). In addition, model diesters and diurethanes were synthesized by reacting PBHQ and HSHP with benzoyl chloride and phenyl isocyanate, respectively. Model compounds and polymers were characterized by FT-IR and ¹H-NMR spectroscopy as well as by DTA and TGA. Diepoxides were also prepared from the reactions of PBHQ and HSHP with epichlorohydrin which were polymerized in the presence of 4,4′-diaminodiphenylsulfone. The polyesters were the most thermostable polymers obtained. After curing at 240°C for 20 h, they were stable in N₂ up to 345–370°C and afforded anaerobic char yields of 65–75% at 800°C. © 1993 John Wiley & Sons, Inc.     

Segmented polyurethane elastomers derived from aliphatic polycarbonate and poly(ester‐carbonate) soft segments for biomedical applications

A series of biomedical polyurethane elastomers (PURs) based on poly(ester‐carbonate)s (PECs) and polycarbonates (PCs) were synthesized and spectrally characterized fully. PEC or PC diols were synthesized by the ring‐opening polymerization of ε‐caprolactone, trimethylene carbonate, and neopentyl carbonate catalyzed by lipase from Candida antarctica. PURs were prepared by free‐metal method from PEC or PC diols and 4,4′‐methylenebis(phenyl isocyanate), with 1,4‐butanediol as a chain extender. The physical and mechanical properties as well as hydrolytic stability of the obtained PURs were determined. The toxicity of the received polymers was evaluated using bacterial luminescence test and two protozoans assays. The presented preliminary studies suggest that PEC or PC diols prepared in this way might be applied for the synthesis of biomedical PURs with improved hydrolytic stability. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Polyesters from α,α′-dicarbomethoxy-α,α′-diphenyl-p-xylylene and the synthesis and properties of a new quinodimethane

A film forming polyester was obtained from the title compound and 1,4-butanediol. In addition oxidation of the title compound gave rise to 7,8-dicarbomethoxy-7,8-diphenylquinodimethane as a mixture of Z and E isomers. The ¹H-NMR and the electronic characterization of this polymer are discussed. The quinodimethane will undergo 1,6-nucleophilic addition to form an aromatic compound.     

A novel synthesis of α-hydroxy- and α,α′-dihydroxyketone from α-iodo and α,α′-diiodo ketone using photoirradiation

A novel reaction of α-iodo ketone (α-iodocycloalkanone, α-iodo-β-alkoxy ester, and α-iodoacyclicketone) with irradiation under a high-pressure mercury lamp gave the corresponding α-hydroxyketone in good yields. In the case of α,α′-diiodo ketone, α,α′-dihydroxyketone which little has been reported until now was obtained. This reaction affords a new, clean and convenient synthetic method for α-hydroxy- and α,α′-dihydroxyketone.     

Synthesis and properties of fluorinated polyimides from a new unsymmetrical diamine: 1,4‐(2′‐Trifluoromethyl‐4′,4′‐diaminodiphenoxy)benzene

A new aromatic, unsymmetrical ether diamine with a trifluoromethyl pendent group, 1,4‐(2′‐trifluoromethyl‐4′,4″‐diaminodiphenoxy)benzene, was successfully synthesized in three steps with hydroquinone as a starting material and polymerized with various aromatic tetracarboxylic acid dianhydrides, including 4,4′‐oxydiphthalic anhydride, 3,3′,4,4′‐benzophenone tetracarboxylic dianhydride, 2,2′‐bis(3,4‐dicarboxyphenyl)‐hexafluoropropane dianhydride, and pyromellitic dianhydride, via a conventional two‐step thermal or chemical imidization method to produce a series of fluorinated polyimides. The polyimides were characterized with solubility tests, viscosity measurements, IR, ¹H NMR, and ¹³C NMR spectroscopy, X‐ray diffraction studies, and thermogravimetric analysis. The polyimides had inherent viscosities of 0.56–0.77 dL/g and were easily dissolved in both polar, aprotic solvents and common, low‐boiling‐point solvents. The resulting strong and flexible polyimide films exhibited excellent thermal stability, with decomposition temperatures (at 5% weight loss) above 522 °C and glass‐transition temperatures in the range of 232–272 °C. Moreover, the polymer films showed outstanding mechanical properties, with tensile strengths of 74.5–121.7 MPa, elongations at break of 6–13%, and initial moduli of 1.46–1.95 GPa, and good dielectric properties, with low dielectric constants of 1.82–2.53 at 10 MHz. Wide‐angle X‐ray diffraction measurements revealed that these polyimides were predominantly amorphous. These outstanding combined features ensure that the polymers are desirable candidate materials for advanced microelectronic applications. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6836–6846, 2006     

Synthesis of novel α,α′,β-trisubstituted β-lactones

A concise and efficient synthesis of α,α′,β-trisubstituted β-lactones is presented. These novel lactones are easily obtained in five steps and will be dedicated to anionic ring opening polymerization.     

Carbon Magnetic Resonance Spectra of α, β, γ, δ- and α, β, α′, β′- Unsaturated Ketones

Carbon-13 spectra of a series of 26 unsaturated ketones (ortho- and para-cyclo-hexadienones and corresponding open-chain analogues) have been measured by Fourier-transform. Pulse spectroscopy. A complete analysis has been achieved by means of double resonance experiments using noise-modulated and coherent off-resonance proton irradiation and with the aid of non-decoupled spectra. Chemical shifts are interpreted in terms of charge distribution in the dienone system and of methyl substituent effects. Carbon chemical shifts were also obtained for O-protonated ortho- and para-cyclohexadienones. One-bond and long-range carbon-proton and carbon-fluorine spin coupling constants are reported for several compounds.     

Highly Effective and Green Catalytic Approach Toward α,ω‐Dihydroxy‐Telechelic Poly(trimethylenecarbonate)

α,ω‐Dihydroxy‐telechelic poly(trimethylenecarbonate), HO‐PTMC‐OH, is synthesized from the controlled “immortal” ring‐opening polymerization (ROP) of trimethylene carbonate under mild conditions (bulk, 60 °C), using ZnEt₂ or, more efficiently, [(BDI)Zn(N(SiMe₃)₂)] (BDI = CH(CMeNC₆H₃‐2,6‐iPr₂)₂) as catalyst precursor, in the presence of a diol HO‐R‐OH (R = (CH₂)₂ or CH₂C₆H₄CH₂; 0.5–10 equiv. vs Zn) acting both as co‐initiator and chain transfer agent. Alternatively, HO‐PTMC‐OH is prepared upon hydrogenolysis of HO‐PTMC‐OCH₂Ph, initially prepared from the ROP of TMC using the [(BDI)Zn(N(SiMe₃)₂)]/PhCH₂OH system, under smooth operating conditions using Pd/charcoal. Well‐defined dihydroxy‐functionalized PTMCs of molar mass ranging from = 2 000 to 109 500 g · mol⁻¹ were thus quantitatively obtained and fully characterized by NMR, MALDI‐TOF‐MS and SEC analyses. The versatility of this “immortal” ROP allows the preparation of alike α,ω‐functional polyester such as linear HO‐poly(lactide)‐OH, as well as star polymers such as the glycerol‐based PTM‐OH₃.

     

Effect of tin tetrachloride on thermal decompositions of α,α′-azobisisobutyronitrile and dimethyl α,α′-azobisisobutyrate

Thermal decomposition of α,α′-azobisisobutyronitrile (AIBN) and dimethyl α,α′-azobisisobutyrate (MAIB) in the presence of a large amount of tin tetrachloride was investigated to determine the effect of complex formation on the decomposition rates and yields of the recombination products. The addition of tin tetrachloride significantly increased the decomposition rates; the observed first-order rate constant increased by factors of 4.5 and 17 at molar ratios of [SnCl₄]/[AIBN] = 21.65 and [SnCl₄]/[MAIB] = 19.53, respectively. It was found that the decomposition of these azo compounds was also accelerated by the addition of a comparable amount of donor solvent such as ethyl acetate or propionitrile to tin tetrachloride and that the enhancement in rate was accounted for by a larger frequency factor in the Arrhenius equation. Furthermore, the addition of tin tetrachloride seemed to suppress the formation of recombination products, tetramethyl succinonitrile and dimethyl tetramethylsuccinate, of the radicals produced by decomposition.     

Synthesis and Characterization of Fluorinated Polyimide Derived from 3,3′‐Diisopropyl‐4,4′‐diaminodiphenyl‐3′′,4′′‐difluorophenylmethane

A novel aromatic diamine monomer, 3,3′‐diisopropyl‐4,4′‐diaminodiphenyl‐3′′,4′′‐difluorophenylmethane (PAFM), was successfully synthesized by coupling of 2‐isopropylaniline and 3,4‐difluorobenzaldehyde. The aromatic diamine was adopted to synthesize a series of fluorinated polyimides by polycondensation with various dianhydrides: pyromellitic dianhydride (PMDA), 3,3′,4,4′‐biphenyltetracarboxylic dianhydride (BPDA), 4,4′‐oxydiphthalic anhydride (ODPA) and 3,3′,4,4′‐benzophenone tetracarboxylic dianhydride (BTDA) via the conventional one‐step method. These polyimides presented excellent solubility in common organic solvents, such as N,N‐dimethylformamide (DMF), N,N‐dimethyl acetamide (DMAc), dimethyl sulfoxide (DMSO), N‐methyl‐2‐pyrrolidone (NMP), chloroform (CHCl₃), tetrahydrofuran (THF) and so on. The glass transition temperatures (T_g) of fluorinated polyimides were in the range of 260–306°C and the temperature at 10% weight loss in the range of 474–502°C. Their films showed the cut‐off wavelengths of 330–361 nm and higher than 80% transparency in a wavelength range of 385–463 nm. Moreover, polymer films exhibited low dielectric properties in the range of 2.76–2.96 at 1 MHz, as well as prominent mechanical properties with tensile strengths of 66.7–97.4 MPa, a tensile modulus of 1.7–2.1 GPa and elongation at break of 7.2%–12.9%. The polymer films also showed outstanding hydrophobicity with the contact angle in the range of 91.2°–97.9°.     

Synthesis and polymerization of cyano-substituted monomers derived from 4-amino-α-methyl-β,β′-dicyanostyrene

A novel class of polymer precursors of the general formula, where A is an aromatic structure bearing amide or imide linkages, were synthesized. More particularly, 4-aminoacetophenone was condensed with malononitrile to afford 4-amino-α-methyl-β,β′-dicyanostyrene ( 1 ). The condensation of the latter with half molar amount of terephthaloyl dichloride, pyromellitic dianhydride, or benzophenone tetracarboxylic dianhydride yielded the polymer precursors. In addition, compound 1 was condensed with an equimolar amount of maleic anhydride to afford the corresponding maleimide. The monomers were characterized by elemental analyses, FT-IR, ¹H-NMR, and DTA. Crosslinked resins were obtained upon curing the monomers at 300°C for 72 h. They were stable up to 381-422°C in N₂ or air and afforded anaerobic char yields of 64-68% at 800°C. © 1994 John Wiley & Sons, Inc.     

Synthesis and structure of (4R,5R)-α,α,α′,α′-2,2-hexaphenyl-4,5-dimethanol-1,3-dioxolane

We report the synthesis of the 1,4-diol (4R,5R)-α,α,α′,α′-2,2-hexaphenyl-4,5-dimethanol-1,3-dioxolane from dimethyl-L-tartrate and benzophenone. The X-ray and the IR structural studies on show that this compound has a preferred conformation with OHPh interactions which are different from related compounds.     

Resonance Raman spectra of metalloporphyrins. On the methine-bridge vibrations of ferric octaethylporphyrins and its α′, β′, γ′, and δ′ deutero derivatives

Raman spectra of Fe³⁺ and Pd²⁺ octaethylporphyrin (OEP) and their α′, β′, γ′, and δ′ deutero derivatives were measured with the 5145, 4880 and 4765 Å lines of an Ar ion laser. Raman bands due to methine-bridge stretching vibrations were assigned and their vibrational amplitudes were calculated from the observed frequency shifts on deuterium substitution of methine-bridge hydrogens. These vibrations correspond to the spin-state sensitive Raman bands of heme proteins. On the basis of symmetry considerations and the observed polarizations, vibrational assignments of other Raman bands were made.     

Polyesters,polyurethanes, and epoxy resin derived from 2,2′-(1,4-phenylenedivinylene)bis-5-hydroxypyridine

2,2′-(1,4-Phenylenedivinylene)bis-5-hydroxypyridine (PBHP) was used as a starting material for preparing new polyesters and polyurethanes as well as a diepoxide-bearing styrylpyridine segments. The diesters were prepared by reacting PBHP with terephthaloyl or adipoyl dichloride utilizing the interfacial polycondensation method. The diesters were prepared from the reaction of PBHP with tolylene diisocyanate or methylenebis(4-phenylisocyanate). In addition, a model diester and diurethane were synthesized by reacting PBHP with benzoyl chloride and phenyl isocyanate, respectively. Both model compounds and polymers were characterized by IR and ¹H-NMR spectroscopy, as well as by DTA and TGA. A diepoxide was also prepared from the reaction of PBHP with epichlorohydrin which was polymerized in the presence of 4,4′-diaminodiphenylsulfone. The polyester derived from PBHP and terephthaloyl dichloride was the most thermostable polymer obtained. It was stable in N₂ up to 355°C and afforded an anaerobic char yield of 59% at 800°C. The thermal stabilities of polymers were improved by curing.     

5-(α-Fluorovinyl)tryptamines and 5-(α-Fluorovinyl)-3-(N-methyl-1′,2′,5′,6′,-tetrahydropyridin-3′- and -4′-yl)indoles—5-(α-Fluorovinyl)tryptamines

5-(α-Fluorovinyl)tryptamines 4a, 4b and 5-(α-fluorovinyl)-3-(N-methyl-1′,2′,5′,6′-tetrahydropyridin-3′- and -4′-yl) indoles 5a, 5b were synthesized using 5-(α-fluorovinyl)indole ( 7 ). The target compounds are bioisosteres of 5-carboxyamido substituted tryptamines and their tetrahydropyridyl analogs.