Oxidative Reaction Conditions Research Articles

Efficient formal synthesis of (±)-axamide-1 and (±)-axisonitrile-1 via an intramolecular Hosomi–Sakurai reaction

Efficient synthetic route to (±)-axamide-1 and (±)-axisonitrile-1 was established via an intramolecular Hosomi–Sakurai reaction of the corresponding allylsilane derivative, in very short steps. A formal synthesis of (±)-axamide-1 and (±)-axisonitrile-1 was achieved by using an intramolecular Hosomi–Sakurai reaction of the allylsilane derivative, as a key step, in which [(3-but-3-en-1-yl-3-methylcyclohex-1-en-1-yl)methyl](trimethyl)silane was transformed to a bicyclic compound possessing a core carbon framework under the oxidative dihydroxylation reaction conditions, in one step.

Synthesis, characterization, thermal stability, conductivity, and band gaps of substitute oligo/polyamines or polyphenol

AbstractIn this study, the oxidative polycondensation reaction conditions of 3,5‐dichloroaniline (DCA), 3,4,5‐trimethoxyaniline (TMA), 3,5‐bis(trifluoromethyl)aniline (BTFMA), and 4‐{[(3,5‐dichlorophenyl)imino]methyl}phenol (DCPIMP) were studied by using NaOCl oxidant in an aqueous alkaline medium between 40 and 90°C. The structures of the synthesized monomer and polymer were confirmed by FT‐IR, Ultraviolet–visible (UV–vis), 1H‐NMR, and 13C‐NMR and elemental analysis. The characterization was made by TGA–DTA, size exclusion chromatography (SEC), and solubility tests. At the optimum reaction conditions, the yields of oligo‐3,5‐dichloroaniline (ODCA), poly‐3,4,5‐trimethoxy aniline (PTMA), oligo‐3,5‐bis(trifluoromethyl)aniline (OBTFMA), and poly‐4‐{[(3,5‐dichlorophenyl) imino]methyl} phenol (PDCPIMP) were found to be 98, 48, 80, and 83% in using NaOCl oxidant. According to the SEC analysis, the number‐average molecular weight (Mn), weight‐average molecular weight (Mw) and polydispersity index (PDI) values of ODCA, PTMA, and OBTFMA were found to be 2200, 3800 g mol−1, and 1.727; 4700, 7500 g mol−1, and 1.596; and 1690, 1950 g mol−1, and 1.154, respectively. According to TG analysis, the weight losses of ODCA, PTMA, OBTFMA, and PDCPIMP were found to be 78.55, 54.18, 99.38, and 59.70% at 1000°C, respectively. PTMA showed higher stability against thermal decomposition. Electrical conductivity of the polymers was measured, showing that the polymer is a typical semiconductor. The highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO) and electrochemical band gaps ($E'_{\rm g} $) of ODCA, PTMA, OBTFMA, and PDCPIMP were calculated from their absorption edges of cyclic voltammograms. The optical band gaps (Eg) values of all compounds were calculated from UV–vis measurements. Copyright © 2009 John Wiley & Sons, Ltd.

Time-resolved operando X-ray absorption study of CuO–CeO2/Al2O3 catalyst during total oxidation of propane

The local structure of the copper phase of a CuO–CeO2/Al2O3 catalyst and its activity for the total oxidation of propane have been studied under working conditions, using time-resolved X-ray absorption spectroscopy (XAS) in transmission mode at the Cu K edge coupled with on-line mass spectrometry (MS). In the temperature range of 573–723K, the copper phase of the catalyst remains oxidized (i.e. Cu2+) during total oxidation reaction conditions (1%C3H8–5%O2/He), while three species are present (i.e. Cu2+, Cu1+ and Cu0) during reduction (2%C3H8/He) and re-oxidation (10%O2/He) treatments where a two-step mechanism is found. Catalyst reduction is fully reversible, as the Cu2+ nature of the catalyst is recovered after a reduction–oxidation cycle. Re-oxidation of the catalyst is two orders of magnitude faster than its reduction and has an apparent activation energy of 24kJ/mol. On the other hand, catalyst reduction requires an apparent activation energy of 70kJ/mol, which is equal to the apparent activation energy determined under total oxidation reaction conditions. These results give support to a Mars–van-Krevelen reaction scheme with the copper phase of the catalyst being close to a fully oxidized state.

Synthesis, Characterization, Conductivity, Band Gap, and Thermal Analysis of Poly-[(2-mercaptophenyl)iminomethyl]-2-naphthol and Its Polymer–Metal Complexes

Oxidative polycondensation reaction conditions of [(2-mercaptophenyl)iminomethyl]-2-naphthol (2-MPIM-2N) were studied using oxidants such as air and NaOCl in an aqueous alkaline medium between 40 °C and 90 °C. The structure of poly-[(2-mercaptophenyl)iminomethyl]-2-naphthol (P-2-MPIM-2N) was characterized by 1H- 13C NMR, FT-IR, and UV–Vis spectroscopy, size exclusion chromatography (SEC), and elemental analysis. At optimum reaction conditions, the yield of P-2-MPIM-2N was found to be 78 and 82% for air and NaOCl oxidants, respectively. From SEC measurements, the number-average molecular weight (Mn), weight-average molecular weight (Mw) and polydispersity index (PDI) of P-2-MPIM-2N are 2900, 3500 g mol−1 and 1.207; 2200, 2500 g mol−1 and 1.136, for air and NaOCl oxidants, respectively. Polymer–metal complexes were synthesized by the reaction of P-2-MPIM-2N with Co2+, Cu2+, Zn2+, Pb2+ and Cd2+ ions. The highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO), and electrochemical band gaps (\( E^{\prime}_{g} \)) of 2-MPIM-2N and P-2-MPIM-2N were −5.97, −2.66 and 3.31 eV and −5.82, −2.68 and 3.14 eV, respectively. The conductivity of polymer and polymer–metal complexes were determined in the solid state. Conductivity measurements of doped and undoped Schiff base polymer and polymer–metal complexes were carried out at room temperature and atmospheric pressure by the four-point probe technique using an electrometer. The conductivities of the polymer and polymer–metal complexes increased when iodine was used as doping agent.

In situ studies of the oxidation of HCl over RuO2 model catalysts: Stability and reactivity

Structure–activity experiments were performed for the HCl oxidation reaction (Deacon-like process) over RuO2 model catalysts – RuO2(1 1 0) and RuO2(1 0 0) – applying in situ surface X-ray diffraction (SXRD) combined with on-line mass spectrometry. The studied model catalysts turned out to be long-term stable under reaction conditions with gas feed ratios p(HCl):p(O2) ranging from 1:4 to 4:1 in the mbar pressure regime and temperatures as high as 685 K. Even pure HCl exposure in the mbar regime was not able to reduce RuO2 below 600 K; above 650 K chemical reduction of the oxide sets in. Under strongly oxidizing reaction conditions, the (surface) oxides grow slowly in thickness. On-line reactivity experiments of both types of model catalysts in a batch reactor yield a mean turn-over frequency (TOF) of 0.6 Cl2 molecules per second and active site for the HCl oxidation at 650 K and initial partial pressures of p(HCl) = 2 mbar and p(O2) = 0.5 mbar. The HCl oxidation over RuO2 is therefore considered to be structure insensitive.

Structure and properties of a Mo oxide catalyst supported on hollow carbon nanofibers in selective propene oxidation

In situ X-ray absorption spectroscopy (XAS) under reaction conditions of selective propene oxidation was employed to elucidate the local structure of as-prepared and activated molybdenum oxide supported on hollow vapor-grown carbon nanofibers (VGCNF). The local structure of as-prepared Mo x O y -VGCNF was very similar to that of hexagonal MoO 3. During heat treatment in propene- and oxygen-containing atmosphere, as-prepared Mo x O y -VGCNF transforms into activated Mo x O y -VGCNF above 623 K. The local structure around the Mo centers in activated Mo x O y -VGCNF is similar to that of α-MoO 3. Temperature- and time-dependent XAS measurements showed a rapid transformation from hex-MoO 3 to α-MoO 3 supported on VGCNF under reaction conditions. Subsequently, the resulting activated Mo x O y -VGCNF catalyst exhibited a slowly increasing average oxidation state. The latter coincided with the formation of acrylic acid, which is hardly detectable during catalysis on regular, binary α-MoO 3. Moreover, activated Mo x O y -VGCNF is much more active in the selective oxidation of propene compared to α-MoO 3. The correlation between catalytic selectivity and average oxidation state as a result of suitable reduction–oxidation kinetics corroborates the importance of structural complexity rather than chemical complexity.

Structural characterization of vanadium oxide catalysts supported on nanostructured silica SBA-15 using X-ray absorption spectroscopy

The local structure of vanadium oxide supported on nanostructured SiO2 (VxOy/SBA-15) was investigated by in situ X-ray absorption spectroscopy (XAS). Because the number of potential parameters in XAS data analysis often exceeds the number of "independent" parameters, evaluating the reliability and significance of a particular fitting procedure is mandatory. The number of independent parameters (Nyquist) may not be sufficient. Hence, in addition to the number of independent parameters, a novel approach to evaluate the significance of structural fitting parameters in XAS data analysis is introduced. Three samples with different V loadings (i.e. 2.7 wt %, 5.4 wt %, and 10.8 wt %) were employed. Thermal treatment in air at 623 K resulted in characteristic structural changes of the V oxide species. Independent of the V loading, the local structure around V centers in dehydrated VxOy/SBA-15 corresponded to an ordered arrangement of adjacent V2O7 units. Moreover, the V2O7 units were found to persist under selective oxidation reaction conditions.

Molecular weight dependent antistaphylococcal activities of oligomers/polymers synthesized from 3-aminopyridine

The main aim of this study was to investigate the relationship between molecular weight and the antistaphylococcal activity of oligomers/polymers synthesized from 3-aminopyridine. Different oligomers/polymers were synthesized from 3-aminopyridine by changing the oxidative polycondensation reaction conditions. They were characterized by size exclusion chromatography and their antibacterial activities were compared by employing standardized susceptibility assays. The obtained experimental results demonstrated that 3-aminopyridine had no antistaphylococcal activity. However, as a result of polymerization, strong antistaphylococcal activity was obtained. Oligomers/polymers synthesized from 3-aminopyridine had varying degrees of antistaphylococcal activity and the maximum activity was obtained from relatively very short oligomers. It was therefore concluded that polymerization of 3-aminopyridine is required for antistaphylococcal activity and strength of this activity depends on the molecular weights of the synthesized molecules.

Oxidative Carbon−Carbon Bond Formation in the Synthesis of Bioactive Spiro β-Lactams

New oxidative dearomatization procedures leading to spiro beta-lactams and oxindoles were developed. By a variation of the oxidative reaction conditions, the usefulness of phenolic amides, derived from 4-aminophenol, in the synthesis of structurally different types of molecules was demonstrated.

CO oxidation over Ru(0 0 0 1) at near-atmospheric pressures: From chemisorbed oxygen to RuO 2

RuO 2(1 1 0) was formed on Ru(0 0 0 1) under oxygen-rich reaction conditions at 550 K and high pressures. This phase was also synthesized using pure O 2 and high reaction temperatures. Subsequently the RuO 2 was subjected to CO oxidation reaction at stoichiometric and net reducing conditions at near-atmospheric pressures. Both in situ polarization modulation infrared reflection absorption spectroscopy (PM-IRAS) and post-reaction Auger electron spectroscopy (AES) measurements indicate that RuO 2 gradually converts to a surface oxide and then to a chemisorbed oxygen phase. Reaction kinetics shows that the chemisorbed oxygen phase has the highest reactivity due to a smaller CO binding energy to this surface. These results also show that a chemisorbed oxygen phase is the thermodynamically stable phase under stoichiometric and reducing reaction conditions. Under net oxidizing conditions, RuO 2 displays high reactivity at relatively low temperatures (⩽450 K). We propose that this high reactivity involves a very reactive surface oxygen species, possibly a weakly bound, atomic oxygen or an active molecular O 2 species. RuO 2 deactivates gradually under oxidizing reaction conditions. Post-reaction AES measurements reveal that this deactivation is caused by a surface carbonaceous species, most likely carbonate, that dissociates above 500 K.

Synthesis, characterization, conductivity, band gap, and kinetic of thermal degradation of poly‐4‐[(2‐mercaptophenyl) imino methyl] phenol

AbstractThe oxidative polycondensation reaction conditions of 4‐[(2‐mercaptophenyl) imino methyl] phenol (2‐MPIMP) were studied in an aqueous acidic medium between 40 and 90°C by using oxidants such as air, H2O2, and NaOCl. The structures of the synthesized monomer and polymer were confirmed by FTIR, 1H NMR, 13C NMR, and elemental analysis. The characterization was made by TGA‐DTA, size exclusion chromatography (SEC) and solubility tests. At the optimum reaction conditions, the yield of poly‐4‐[(2‐mercaptophenyl) imino methyl]phenol (P‐2‐MPIMP) was found to be 92% for NaOCl oxidant, 84% for H2O2 oxidant 54% for air oxidant. According to the SEC analysis, the number‐average molecular weight (Mn), weight‐average molecular weight (Mw), and polydispersity index values of P‐2‐MPIMP were found to be 1700 g mol−1, 1900 g mol−1, and 1.118, using H2O2; 3100 g mol−1, 3400 g mol−1, and 1.097, using air; and 6750 g mol−1, 6900 g mol−1, and 1.022, using NaOCl, respectively. According to TG analysis, the weight losses of 2‐MPIMP and P‐2‐MPIMP were found to be 95.93% and 76.41% at 1000°C, respectively. P‐2‐MPIMP showed higher stability against thermal decomposition. Also, electrical conductivity of the P‐2‐MPIMP was measured, showing that the polymer is a typical semiconductor. The highest occupied molecular orbital, the lowest unoccupied molecular orbital, and the electrochemical energy gaps (E′g) of 2‐MPIMP and P‐2‐MPIMP were found to be −6.13, −6.09; −2.65, −2.67; and 3.48, 3.42 eV, respectively. Kinetic and thermodynamic parameters of these compounds investigated by MacCallum‐Tanner and van Krevelen methods. The values of the apparent activation energies of thermal decomposition (Ea), the reaction order (n), pre‐exponential factor (A), the entropy change (ΔS*), enthalpy change (ΔH*), and free energy change (ΔG*) were calculated from the TGA curves of compounds. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

SYNTHESIS, CHARACTERIZATION, THERMAL ANALYSIS, CONDUCTIVITY AND BAND GAPS OF OLIGO {4-[(2-HYDROXYL-1-NAPHTHYL)METHYLENE]-AMINOBENZOIC ACID}

The oxidative polycondensation reaction conditions of 4-((2-hydroxyl-1-naphthyl)methylene)aminobenzoic acid (4-HNMABA) with H2O2, air O2 and NaOCl were studied in an aqueous alkaline medium between 40°C and 90°C. The structure of oligo {4-((2-hydroxyl-1-naphthyl)methylene)aminobenzoic acid} (O-4-HNMABA) was characterized by using 1 H-NMR, 13 C-NMR, FT-IR, UV-Vis, size exclusion chromatography (SEC) and elemental analysis techniques. At the optimum reaction conditions, the yield of O-4-HNMABA was found to be 70% for H2O2 oxidant, 94% for air O2 oxidant and 87% for NaOCl oxidant. According to the SEC analysis, the number-average molecular weight (Mn), weight-average molecular weight (Mw) and polydispersity index (PDI) values of O-4-HNMABA were found to be 850, 1350 and 1.59, using H2O2, 1800, 2200 and 1.22, using air O2 and 2200, 3000 and 1.36, using NaOCl, respectively. TGA-DTA analyses showed that O-4-HNMABA was more stable than 4-HNMABA. The highest occupied molecular orbital, the lowest unoccupied molecular orbital and electrochemical energy gaps ( ' Eg ) of 4-HNMABA and O-4-HNMABA were found to be −6.34, −6.56; −2.67, −3.04; 3.67 and 3.52 eV, respectively, by cyclic voltammetry (CV). According to UV-Vis measurements, optical band gaps (Eg) of 4-HNMABA and O-4-HNMABA were found to be 3.12 and 3.03 eV, respectively.

In situ structure–activity correlation experiments of the ruthenium catalyzed CO oxidation reaction

The complex structure–activity correlation of the CO oxidation on ruthenium has been studied in a batch reactor by using in situ surface X-ray diffraction (SXRD) and on-line mass spectrometry. Two distinct active phases are identified at higher pressures in the mbar range depending on the reaction conditions: a non-oxidic phase and a RuO 2(1 1 0) layer of variable thickness ranging from 1.5 nm to 10 nm. For reaction temperatures lower than 520 K the experimental turnover frequency (TOF) numbers are shown to be almost identical for the two types of active phases. Above 520 K the RuO 2(1 1 0) layer turned out to be much more active than the non-oxidic phase. Kinetic reaction experiments on the RuO 2(1 1 0) phase reveal an activation energy of 78 ± 10 kJ/mol which is in perfect agreement with corresponding reactivity experiments on supported and powder RuO 2 catalyst. Under oxidizing reaction conditions and high concentration of CO 2 in the gas mixture, the RuO 2(1 1 0) model catalyst shows reversible product-poisoning.

Preparation, characterization and catalytic properties of carbon nanofiber-supported Pt, Pd, Ru monometallic particles in aqueous-phase reactions

Carbon nanofibers (CNF) synthesized by catalytic chemical vapor deposition (CVD) method were used to prepare supported platinum, palladium and ruthenium monometallic (2.0wt.%) catalysts by means of incipient-wetness impregnation method. The CNF support and catalysts were characterized by X-ray powder diffraction (XRD), nitrogen adsorption/desorption isotherms, volumetric chemisorption of hydrogen, temperature-programmed reduction (H2-TPR) and scanning electron microscopy (SEM). Solids were tested in catalytic wet-air oxidation (CWAO) of phenol aqueous solution (180–240°C and 10.0bar of oxygen partial pressure) carried out in a continuous-flow trickle-bed reactor. Trends of phenol and total organic carbon (TOC) conversion demonstrate that the CNF support and CNF-Pt catalyst did not exhibit constant activity for CWAO of phenol. A decrease of catalyst activity, detection of carbon dioxide in the off-gas stream while examining catalyst stability and significant textural changes observed, provide an evidence that under net oxidizing reaction conditions gasification of the CNF support occurs. The prepared catalysts were also tested in liquid-phase thermal decarboxylation of formic acid in inert atmosphere (60–220°C). Among solids examined, the CNF-Pd exhibited the highest activity. At the employed conditions, no decomposition of the CNF support was observed during the thermal decarboxylation of formic acid.

Synthesis, characterization, thermal stability, conductivity and band gaps of monomer and oligo-4-[(thien-2-ylmethylene) amino] phenol

AbstractIn this study, the oxidative polycondensation reaction conditions of 4- [(thien-2-yl-methylene) amino] phenol (4-TMAP) by using oxidants such as air O2, H2O2 and NaOCl were studied in an aqueous alkaline medium between 313 and 363 °K. The structures of the synthesized monomer and oligomer were confirmed by FT-IR, UV-vis, NMR and elemental analysis. The characterization was made by TG-DTA, size exclusion chromatography (SEC) and solubility tests. At the optimum reaction conditions, the yield of oligo-4-[(thien-2-yl-methylene) amino] phenol (O-4- TMAP) was found to be 36% for air O2 oxidant, 40% for H2O2 oxidant and 47% for NaOCl oxidant. According to TG analysis, the weight losses of 4-TMAP and O-4- TMAP were found to be 58.11% and 51.38% at 1273°K, respectively. O-4-TMAP was shown higher stability against thermal decomposition. Also, electrical conductivity of the O-4-TMAP was measured, showing that the polymer is a typical semiconductor. The highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO) and electrochemical energy gaps ( ' gE ) of 4- TMAP and O-4-TMAP were found to be -6.13, -6.02; -2.72, -2.69; 3.41 and 3.33 eV, respectively.

Structure and properties of a supported MoO 3–SBA-15 catalyst for selective oxidation of propene

Local structure and catalytic properties of molybdenum oxide supported on nanostructured SiO 2 (SBA-15) were studied under reaction conditions by combined X-ray absorption spectroscopy (XAFS) and mass spectrometry. MoO 3 supported on SBA-15 exhibits stability and catalytic properties different from those of binary bulk oxides. The interaction between support and molybdenum oxide stabilizes particular hexagonal MoO 3 structure that is highly active and selective. The hex-MoO 3–SBA-15 is stable under reducing (propene) and oxidizing reaction conditions in the temperature range from 20 to 500 °C. In contrast to bulk hex-MoO 3, the onset of activity at about 250 °C is not accompanied by a transformation to α-MoO 3. Moreover, in contrast to α-MoO 3, hex-MoO 3–SBA-15 is capable of directly oxidizing propene to acrylic acid without additional metal sites.

Kinetics of CO and H 2 oxidation over CuO-CeO 2 catalyst in H 2 mixtures with CO 2 and H 2O

The kinetics of CO and H 2 oxidation over a CuO-CeO 2 catalyst were simultaneously investigated under reaction conditions of preferential CO oxidation (PROX) in hydrogen-rich mixtures with CO 2 and H 2O. An integral packed-bed tubular reactor was used to produce kinetic data for power-law kinetics for both CO and H 2 oxidations. The experimental results showed that the CO oxidation rate was essentially independent of H 2 and O 2 concentrations, while the H 2 oxidation rate was practically independent of CO and O 2 concentrations. In the CO oxidation, the reaction orders were 0.91, −0.37 and −0.62 with respect to the partial pressure of CO, CO 2 and H 2O, respectively. In the H 2 oxidation, the orders were 1.0, −0.48 and −0.69 with respect to the partial pressure of H 2, CO 2 and H 2O, respectively. The activation energies of the CO oxidation and the H 2 oxidation were 94.4 and 142 kJ/mol, respectively. The rate expressions of both oxidations were able to predict the performance of the PROX reactor with accuracy. The independence between the CO and the H 2 oxidation suggested different sites for CO and H 2 adsorption on the CuO-CeO 2 catalyst. Based on the results, we proposed a new reaction model for the preferential CO oxidation. The model assumes that CO adsorbs selectively on the Cu + sites; H 2 dissociates and adsorbs on the Cu 0 sites; the adsorbed species migrates to the interface between the copper components and the ceria support, and reacts there with the oxygen supplied by the ceria support; and the oxygen deficiency on the support is replenished by the oxygen in the reaction mixture.

SYNTHESIS, CHARACTERIZATION, THERMAL DEGRADATION AND ELECTRICAL CONDUCTIVITY OF OLIGO[2-(2-HYDROXYPHENYLIMINOMETHYL-BENZYLIDENE)AMINOPHENOL] AND OLIGOMER-METAL COMPLEXES

The oxidative polycondensation reaction conditions of 2-[(2-hydroxyphenyliminomethylbenzylidene)amino-phenol] (2-HPIMBAP) has been accomplished by using air O2 and NaOCl oxidants in an aqueous alkaline medium between 50–90°C. The optimum reaction conditions of the oxidative polycondensation and the main parameters of the process were established. At the optimum reaction conditions, yield of the products were found to be 67.72% and 61.49% for air O2 and NaOCl oxidants respectively. The structures of the monomer and oligomer were confirmed by FT-IR, UV-Vis, 1H-NMR and 13C-NMR and elemental analysis. Also, TGA-DTA, SEC techniques and solubility tests were applied for characterization. 1H-NMR and 13C-NMR data show that the polymerization proceeded by the C-C and C-O-C coupling systems of ortho and para positions and oxyphenylene according to -OH group of 2-HPIMBAP. The number-average molecular weight (Mn), weight-average molecular weight (Mw) and polydispersity index (PDI) values of oligo[2-(2-hydroxyphenylim...

Synthesis, characterization, conductivity, band gap and thermal analysis of poly-2-[(4-mercaptophenyl) imino methyl] phenol and some of its polymer–metal complexes

The oxidative polycondensation reaction conditions of 2-[(4-mercaptophenyl) imino methyl] phenol (4-MPIMP) was studied in an aqueous alkaline medium between 30 and 90 °C by using oxidants such as air O 2, NaOCl and H 2O 2. Polymer–metal complex compounds were synthesized from the reactions of poly-2-[(4-mercaptophenyl) imino methyl] phenol (P-4-MPIMP) with Cr 3+, Co 2+, Ni 2+, Cu 2+, Mn 2+, Zn 2+, Pb 2+, Cd 2+ and Zr 4+ ions. The structures of these monomer and polymer were identified from UV–vis, FT-IR, 1H NMR, 13C NMR and elemental analysis. While thermal analysis of P-4-MPIMP and polymer–metal complexes were made by TGA–DTA, the number-average molecular weight ( M n), weight-average molecular weight ( M w) and polydispersity index (PDI) values of this polymer were determined by size exclusion chromatography (SEC). According to TG–DTA analyses, P-4-MPIMP–Cu was found to be higher stable than other synthesized polymer and polymer–metal complexes. While conductivity measurements of polymer and polymer–metal complexes were done by electrometer using four point probe techniques, electrochemical and optical band gap values of 4-MPIMP, P-4-MPIMP and polymer–metal complexes were determined by using cyclic voltammetry and UV–vis measurements. Conductivity and band gap values show that this polymer and polymer–metal complexes are a typical semiconductor.

Synthesis, characterization, thermal stability, conductivity, and band gap of a new aromatic polyether containing an azomethine as a side

AbstractIn this study, the oxidative polycondensation reaction conditions of 4‐[(4‐methylphenyl)iminomethyl]phenol (4‐MPIMP) were studied by using oxidants such as air O2, H2O2, and NaOCl in an aqueous alkaline medium between 50 and 90°C. The structures of the synthesized monomer and polymer were confirmed by FTIR, UV–vis, 1H–13C‐NMR, and elemental analysis. The characterization was made by TGA‐DTA, size exclusion chromatography (SEC), and solubility tests. At the optimum reaction conditions, the yield of poly‐4‐[(4‐methylphenyl)iminomethyl]phenol (P‐4‐MPIMP) was found to be 28% for air O2 oxidant, 42% for H2O2 oxidant, and 62% for NaOCl oxidant. According to the SEC analysis, the number–average molecular weight (Mn), weight–average molecular weight (Mw), and polydispersity index values of P‐4‐MPIMP were found to be 4400 g mol−1, 5100 g mol−1, and 1.159, using H2O2, and 4650 g mol−1, 5200 g mol−1, and 1.118, using air O2, and 5100 g mol−1, 5900 g mol−1, and 1.157, using NaOCl, respectively. According to TG analysis, the weight losses of 4‐MPIMP and P‐4‐MPIMP were found to be 85.37% and 72.19% at 1000°C, respectively. P‐4‐MPIMP showed higher stability against thermal decomposition. Also, electrical conductivity of the P‐4‐MPIMP was measured, showing that the polymer is a typical semiconductor. The highest occupied molecular orbital and the lowest unoccupied molecular orbital energy levels and electrochemical energy gaps (E) of 4‐MPIMP and P‐4‐MPIMP were found to be −5.76, −5.19; −3.00, −3.24; 2.76 and 1.95 eV, respectively. According to UV–vis measurements, optical band gaps (Eg) of 4‐MPIMP and P‐4‐MPIMP were found to be 3.34 and 2.82 eV, respectively. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007