Synthesis and polymerization of 2,5-dimethylene-2,5-dihydrothieno[3,2-b]thiophene derivatives: The structure and reactivity of quinonoid monomers

Novel 2,5-dimethylene-2,5-dihydrothieno[3,2-b]thiophene derivatives such as 2,5-bis[di(ethylthio)methylene]-2,5-dihydrothieno[3,2-b]thiophene ( 4b ) and 2,5-bis[cyano(ethylthio)methylene]-2,5-dihydrothieno[3,2-b]thiophene ( 4c ) were successfully synthesized as isolable crystals. Polymerization behavior of 2,5-bis(dicyanomethylene)-2,5-dihydrothieno[3,2-b]thiophene ( 4a ), 4b , and 4c was investigated. 4a , 4b , and 4c are not homopolymerizable with any initiators and also not copolymerizable with vinyl monomers such as styrene (St), methyl methacrylate, and acryronitrile except for an alternating copolymerization of 4a with St. 4a , 4b , and 4c did not copolymerize with 7,8-bis(butoxycarbonyl)-7,8-dicyanoquinodimethane (BCQ) as a highly conjugated comonomer and instead only homopolymer of BCQ was obtained, indicating that they are much less reactive than BCQ. To obtain the relative reactivity among 1c , 2c , and 4c , the rate of addition reaction of 2,2′-azobis(isobutyronitrile) (AIBN) with 4c was compared with those of AIBN with 7,8-bis(ethylthio)-7,8-dicyanoquinodimethane ( 1c ) and with 2,5-bis[cyano(ethylthio)methylene]-2,5-dihydrothiophene ( 2c ) by NMR spectroscopy and analyzed with the first-order kinetics. The relative reactivity among 1c , 2c , and 4c was found to be as follows: 1c > 4c > 2c . The relationship between structure and reactivity for the quinonoid compounds was discussed. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3027–3039, 1999     

Synthesis and characteristics of the mass spectra of 2,5-dimercapto-2,5-dimethyltetrahydrothiophene

2,5-Dimercapto-2,5-dimethyltetrahyrothiophene was synthesized by the reaction of 1-iodopropan-2-one with hydrogen sulfide in an ether solution of hydrogen chloride at-70°C. Its structure was established by mass spectrometry, ¹H and ¹³C NMR spectroscopy. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, 216–219, February, 2007.     

Silver(I) Complexes of Schiff Bases Derived from Thiophene-2,5-dicarboxaldehyde and Furan-2,5-dicarboxaldehyde

The reactions of Schiff bases, derived by the condensation of thiophene-2,5-dicarbaldehyde and furan-2,5-dicarbaldehyde with 2-thienylmethylamine or 2-furanmethylamine, with silver nitrate have been studied in refluxing anhydrous methanol under nitrogen atmosphere. Complexes thus formed have been isolated and characterized by elemental analysis, electrical conductance, cyclic voltammetry, and ¹H NMR, ¹³C NMR, IR, LTV-Vis, and mass spectroscopic studies. The experimental results reveal that the complexes are primarily ionic in nature, consisting of (L)₃Ag₂ dication and Ag(NO₃)₃ negatively charged dianions. The molecular structure of one of the complexes, [((C₄H₃O)CH₂N? CH(C₄H₂S)CH? NCH₂(C₄H₃O))₃Ag₂] [Ag(NO₃)₃] has been studied in the solid state. The complex is crystallized in the triclinic space group $ {\rm P}\bar 1 $ with a = 12.889(7) Å, b = 14.884(5) Å, c = 15.084(6) Å, α = 92.18(4)°, β = 79.78(4)°, γ = 110.92(4)°. The structure is disordered. Each Ag in dication is tri-coordinated by three azomethine N atoms from three ligands, and each ligand employs two azomethine N atoms to coordinate to two Ag ions such that the geometry around the Ag ?Ag axis conforms to a propeller-shape. The two Ag ions are between the two N₃ planes with Ag ? Ag distance ca. 4.8.1 Å. There is no bonding between any Ag ion and any thiophene of the three ligands. However, two Ag ions and three thiophene S atoms form a trigonal bipyramidal geometry.     

Synthesis and properties of poly(isosorbide 2,5-furandicarboxylate-co-ε-caprolactone) copolyesters

Bio-based poly(isosorbide 2,5-furandicarboxylate-co-ε-caprolactone) (PIFCL) copolyesters were synthesized from 2,5-furandicarboxylic acid, isosorbide and ε-caprolactone. The obtained copolyesters were characterized by ¹H NMR, ¹³C NMR, intrinsic viscosity, GPC, DSC, TGA and tensile testing. The NMR characterization results confirmed the insertion of lactones units into poly(isosorbide 2,5-furandicarboxylate) (PIF) chains. All PIFCL copolyesters were amorphous with T_{D, 5%} higher than 300 °C. The glass transition temperatures of PIFCLs with FDCA molar ratio from 74% to 45% were within the range of 132.1 °C and 72.4 °C. Tensile testing revealed that introduction of ε-caprolactone into PIF chain imparted PIFCL with excellent mechanical performance, typically, PIFCL polyseter with FDCA molar ratio of 45% had a Young's modulus 858 ± 92 MPa, a tensile strength 44 ± 4 MPa and an elongation at break 480 ± 45%.     

Chiral building blocks from biomass: 2,5-diamino-2,5-dideoxy-1,4-3,6-dianhydroiditol

An efficient route towards the synthesis of 2,5-diamino-2,5-dideoxy-1,4-3,6-dianhydroiditol 4 has been developed resulting in significant improvements in both isolated yields and purity when compared to literature procedures. As a consequence, resin-grade 2,5-diamino-2,5-dideoxy-1,4-3,6-dianhydroiditol 4 has become available for laboratory scale step-growth polymer synthesis. Additionally, an interesting renewable chiral 2-amino-2-deoxy-1,4-3,6-dianhydroiditol 10, has been isolated.     

Synthesis and Characterization of a Novel Poly(aryl ether) Containing 4-Chloro-2,5-diphenyloxazole

4-Chloro-2,5-bis(4-fluorophenyl)oxazole monomer has successfully been synthesized using cyclization reaction of 4-fluorobenzoyl cyanide with 4-fluorobenzaldehyde. This monomer was converted to poly(aryl ether)s by nucleophilic substitution of the fluorine atoms on the benzene rings of oxazole monomer with bisphenol A. The influence of the reaction time on the molecular weight had been investigated. The polymers were identified by FT-IR,¹H-NMR and TGA. The products exhibited weight-average molar masses up to 2.81 x 10⁴g mol⁻¹ in GPC. These poly(aryl ether)s showed very high thermal stability up to 363 °C for 5 % weight loss in TGA under N₂.     

Photochromic dihetarylethenes. 13. Optimization of conditions for the acylation of 2,5-dimethylthiophene with squaric acid dichloride

The conditions for acylation of 2,5-dimethylthiophene with squaric acid dichloride were optimized, and 3,4-bis(2,5-dimethylthiophen-3-yl)cyclobut-3-ene-1,2-dione was obtained in good yield. X-ray diffraction analysis demonstrated that the by-product has the structure of 1a,1b-dichloro-5-(2,5-dimethylthiophen-3-yl)-3-hydroxy-4,5a-dimethyl-1b,4a,5,5a-tetrahydro-1aH-1-thiacyclopropa[a]pentalen-2-one.     

Polymerization behaviour of 2,5-dimethylene- 2,5-dihydrofuran

Spontaneous homopolymerization of 2,5-dimethylene-2,5-dihydrofuran (DDF) was studied. The polymerization rates in two different initial monomer concentrations of DDF were analyzed with the first-order and second-order kinetics, and the homopolymerization of DDF was found to obey the first-order kinetics. The Arrhenius plot of the apparent rate constants at 30, 40, 50, and 60° gave an overall activation energy of 68.0 kJ/mol for the polymerization of DDF. From the comparison of the apparent rate constants at –78° and the time (the so-called half-life time) to decrease in half the monomer concentration for DDF with the corresponding values for p-xylylene (QM), DDF was found to be a less reactive monomer than QM. The copolymerizations of DDF with vinyl monomers such as acrylonitrile (AN), α-chloroacrylonitrile (CIAN), diethyl fumarate (DEF), and fumaronitrile (FN) were carried out in chloroform at 50° in the presence of AIBN to obtain the monomer reactivity ratios r₁(DDF) = 30.0 ± 3.0 and r₂ (AN) = 0 for the DDF-AN system, r₁ (DDF) = 1.55 ± 0.2 and r₂(CIAN) = 0 for the DDF-CIAN system, r₁(DDF) = 3.88 ± 0.2 and r₂(DEF) = 0 for the DDF-DEF system, and r₁(DDF) = 2.41 ± 0.1 and r₂ (FN) = 0 for the DDF-FN system, respectively. As the monomer reactivity ratios of r₂ for all systems were zero, Q and e values of DDF were calculated from the combination of two r₁ (DDF) values of any two copolymerization systems to be the 7.64 to 6.63 ×10²¹ range for Q and the –0.70 to –6.31 range for e, indicating that DDF is a highly conjugative and electron-donating monomer. © 1995 John Wiley & Sons, Inc.     

Polymerization behavior of 2,5‐bis(dicyanomethylene)‐ 2,5‐dihydrofuran

2,5‐Bis(dicyanomethylene)‐2,5‐dihydrofuran (TCNF) is not homopolymerizable with any initiators, but copolymerizable with styrene (St) in an alternating fashion. Reactivity of TCNF was compared with that of 2,5‐bis(dicyanomethylene)‐2,5‐dihydrothiophene (TCNT) on the basis of the terpolymerization of the TCNT‐TCNF‐St system and the rates of addition reactions of AIBN with TCNT and with TCNF. TCNF was found to be lower in reactivity than TCNT. The relative reactivity was explained with the energy difference between quinonoid structure and benzenoid one. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1285–1292, 1999     

Reactions of guaiazulene with thiophene-2,5-dicarbaldehyde and furan-2,5-dicarbaldehyde in methanol in the presence of hexafluorophosphoric acid: a facile preparation and properties of delocalized dicarbenium-ion compounds stabilized by two 3-guaiazulenyl groups and a thiophene (or furan) ring

Reaction of guaiazulene (1) with thiophene-2,5-dicarbaldehyde (2) in methanol in the presence of hexafluorophosphoric acid at 25 °C for 3 h gives as high as 90% isolated yield of the delocalized dicarbenium-ion compound, 2,5-thienylenebis(3-guaiazulenylmethylium) bis(hexafluorophosphate) (3). Similarly, reaction of 1 with furan-2,5-dicarbaldehyde (4) under the same conditions as the above reaction affords the corresponding dicarbenium-ion compound, 2,5-furylenebis(3-guaiazulenylmethylium) bis(hexafluorophosphate) (5), in 84% isolated yield. Along with a facile preparation and the spectroscopic and electrochemical properties of 3 and 5, comparative studies on the ¹H and ¹³C NMR spectral and chemical properties of 3 and 5 with those of the delocalized mono- and dicarbenium-ion compounds [i.e., (3-guaiazulenyl)(2-thienyl)methylium hexafluorophosphate (7), (2-furyl)(3-guaiazulenyl)methylium hexafluorophosphate (9), α,α′-bis(3-guaiazulenylmethylium) bis(tetrafluoroborate) (10), 1,2-phenylenebis(3-guaiazulenylmethylium) bis(hexafluorophosphate) (11), and 1,4-phenylenebis(3-guaiazulenylmethylium) bis(tetrafluoroborate) (12)] are reported. Moreover, referring to the results of the X-ray crystallographic analyses of 7, 9, 11, and 12, the optimized 2,5-thienylenebis(3-guaiazulenylmethylium)- and 2,5-furylenebis(3-guaiazulenylmethylium)-ion structures for 3 and 5, calculated by a WinMOPAC (version 3.0) program using PM3 as a semiempirical Hamiltonian, are described.     

P,P′-(2,5-Dihydroxy-3,6-dimethyl-2,5-dioxo-2λ5,5λ5-[1,4,2,5]-dioxadiphosphinan-2,5-diyl)-bis-phosphonsäure

P,P′-(2,5-Dihydroxy-3,6-dimethyl-2,5-dioxo-2λ⁵,5λ⁵-[1,4,2,5]dioxadiphosphinane-2,5-diyl)-bis-phosphonic Acid The tetrahydrate 1 of the title compound crystallizes in the monoclinic space group P2₁/c with a = 845.8, b = 1 098, c = 981.7 pm, β = 113.02° and Z = 2. The anions of the oxonium compound (H₃O⁺ · H₂O)₂(C₄H₁₀O₁₂P₄^2?) are layered by hydrogen bridges. The ¹H, ¹³C and ³¹P NMR spectra (4 and 5 spin systems) are discussed.     

2,5-二苯腙基-1,3,4-噻二唑类化合物的合成及抗腐蚀性能研究

以2,5-二巯基-1,3,4-噻二唑为原料, 与水合肼反应制得2,5-二肼基-1,3,4-噻二唑, 再将其与取代苯甲醛缩合, 得到了6种新的2,5-二苯腙基-1,3,4-噻二唑类化合物, 其结构经元素分析、红外、¹H NMR及质谱等方法所证实. 6种噻二唑衍生物对喷气燃料银片腐蚀有一定的抑制作用.     

Renewable resources based polymers: Synthesis and characterization of 2,5-diformylfuran-urea resin

Condensation of renewable resources based monomer 2,5-diformylfuran (DFF) and urea at 110 °C by melting a solid mixture gives a crystalline polymer resin in 90% yield. This resin was characterized by elemental analysis, ¹H, ¹³C and ¹H-¹H COSY NMR, IR, UV, TGA and DTA. The structural unit of this new material consists of one DFF molecule condensed with two urea molecules at the aldehyde group of DFF. A homologous resin was prepared by using 5,5′-oxydimethylenebis(2-furaldehyde) and urea in 84% yield via a similar procedure and characterized as well.     

Salts of 2,5-dimercapto-1,3,4-thiadiazole

Reaction of 2,5-dimercapto-1,3,4-thiadiazole with ammonia or pyridine gives monoammonium or monopyridinium slats, and the reaction with hydrazine hydrate gives both mono- and dihydrazine salts, which was confirmed by alkylation of the salts obtained. Difference in the chemical shifts of the SCH₂R groups was found in the¹H NMR spectra of the mono- and dialkyl-substituted 2,5-dimercapto-1,3,4-thiadiazoles.Institute of Chemistry, Vilnius LT-2600, LithuaniaTranslated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 682–687, May, 2000.     

Determination of dissociation energies of N-H bond in the 4-anilinodiphenylaminyl radical and O-H bond in the 2,5-dichloro-4-hydroxyphenoxyl radical from the equilibrium constants of chain reactions in quinoneimine-hydroquinone systems

The temperature dependences of the equilibrium constants of two chain reversible reactions in quinonediimine (quinonemonoimine)—2,5-dichlorohydroquinone systems in chlorobenzene were studied. The enthalpy of equilibrium of the reversible reaction of quinonediimine with 4-hydroxydiphenylamine was estimated from these data (ΔH = − 14.4±1.6 kJ mol⁻¹) and a more accurate value of the N-H bond dissociation energy in the 4-anilinodiphenylaminyl radical was determined (D _NH = 278.6±3.0 kJ mol⁻¹). A chain mechanism was proposed for the reaction between quinonediimine and 2,5-dichlorohydroquinone, and the chain length was estimated (ν = 300 units) at room temperature. Processing of published data on the rate constant of the reaction of styrylperoxy radicals with 2,5-dichlorohydroquinone in the framework of the intersecting parabolas method gave the O-H bond dissociation energy in 2,5-dichlorohydroquinone: D _OH = 362.4±0.9 kJ mol⁻¹. Taking into account these data, the O-H bond dissociation energy in the 2,5-dichlorosemiquinone radical was found: D _OH = 253.6±1.9 kJ mol⁻¹. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1661–1666, October, 2006.     

P,P′-(2,5-Dimethoxy-3,6-dimethyl-2,5-dioxo-2λ5,5λ5-[1,4,2,5]dioxadiphosphinan-2,5-diyl)-bis-phosphonsäuretetramethylester

P,P′-(2,5-Dimethoxy-3,6-dimethyl-2,5-dioxo-2λ⁵,5λ⁵-[1,4,2,5]dioxadiphosphinane-2,5-diyl)-bis-phosphonic acid tetramethylester The title compound 1 is formed by reaction of the corresponding phosphonic acid 2 and orthoformicacidmethylester as a mixture of four stereoisomeres. The RRSS isomer was separated. It crystallizes in the triclinic space group P ?1 with a = 649.2 pm, b = 976.1 pm, c = 1 571.7 pm, α = 80.9°, β = 88.1°, γ = 78.6° and Z = 2. The ³¹P and ¹³C NMR spectra (4 and 5 spin systems) are discussed.     

Determination of cerium(III) ions in soil and sediment samples by Ce(III) PVC-based membrane electrode based on 2,5-dioxo-4-imidazolidinyl

2,5-Dioxo-4-imidazolidinyl was used as an excellent sensing material in the preparation of a PVC membrane for a Ce(III)-selective sensor. The electrode shows a good selectivity for the Ce(III) ion with respect to most common cations including alkali, alkaline earth, transition, and heavy metal ions. The developed sensor exhibits a wide linear response with a slope of 19.6?±?0.3 mV per decade over the concentration range of 1.0?×?10^?6 to 1.0?×?10^?1 M, while the illustrated detection limit is 5.7?×?10^?7 M of Ce(III) ions. Moreover, it is concluded that the sensor response is pH-independent in the range of 3.1–9.8. The applications of the recommended electrode include the determination of concentration of Ce(III) ions in soil and sediment samples, validation with CRM's, and the Ce(III) ion potentiometric titration with EDTA as an indicator electrode.     

Thermal cross-link between 2,5-furandicarboxylic acid-based polyimides and bismaleimide via Diels–Alder reaction

A series of cross-linked polyimides (PIs) were prepared via two-step solution polycondensation from 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride (BPADA) and 2,5-furandicarboxylic acid-based diamines, N,N′-bis(4-amino-2-(trifluoromethyl)phenyl)furan-2,5-dicarboxamide (TFFDA) and N,N′-bis(4-aminophenyl)furan-2,5-dicarboxamide (p-FDDA), followed by thermal crosslinking reaction with bismaleimide. The thermal crosslinking reaction and its mechanism were studied by FTIR spectra and model reaction analysis, which showed Diels–Alder reaction between furan group and maleimide group played a main role in the thermal treatment. The properties of cross-linked PIs were characterized using dynamic mechanical thermal analysis, thermogravimetric analyses, tensile testing, ultraviolet-visible spectra, and wide-angle X-ray diffraction. The cross-linked polyimide film showed improved solvent-resistance, thermal and mechanical properties with T_g values of 234–306^oC, tensile strengths of 82–98 MPa and moduli of 2.3–3.0 GPa.     

A new calcium 2,5-dihydroxybenzoate: Synthesis,characterization and antioxidant studies and stress mediated cytotoxity in MCF-7 cells

The structure and composition of the calcium 2,5-dihydroxybenzoate (calcium gentisate) were studied by single-crystal and powder X-ray diffraction. Single-crystal X-ray analysis revealed that the compound crystallizes in the orthorhombic space group Pbcn. The Ca(II) cation is coordinated in a monodentate fashion by two symmetry-related gentisate anions and five water molecules. The metal ion and one of the water molecules are located on a 2-fold rotation axis. The adjacent monomeric units are assembled into a 3-D supramolecular framework via O–H…O hydrogen bonds. Comparison of the experimental powder pattern with that simulated from single-crystal X-ray data confirmed the purity and homogeneity of the sample. The FT-IR, UV/VIS, ¹H and ¹³C NMR spectra of the calcium 2,5-dihydroxybenzoic acid were registered and analysed. Moreover the effect of calcium complex and 2,5-dihydroxybenzoic acid on basic oxidative stress parameters, such as thiol group content and lipid peroxidation in the human breast cancer cells MCF-7 was studied. The antiradical and ferric reducing power of these compounds was measured by DPPH, CUPRAC and FRAP methods. The chemical reactivity parameters (e.g. HOMO and LUMO orbitals, ionization potential, electron affinity) for Ca 2,5-dHB and 2,5-dHB were calculated at B3LYP/6-311++G7 level of theory and discussed in relation to their antioxidant properties.     

2,5-Dimethoxy-2,5-dihydrofuran chemistry: a new approach to 2(5H)-furanone derivatives

2,5-Dimethoxy-2,5-dihydrofuran is a synthetic equivalent of 2(5H)-furanone or 2-trimethylsilyloxyfuran, useful C₄ synthons in the preparation of 5-substituted-2(5H)-furanone derivatives. The reaction conditions adopted allow to obtain different classes of complex and biologically interesting compounds, in only one step, with high yields.