Azo initiators for the preparation of hydroxyl-terminated polybutadienes

Azo compounds such as di(4-hydroxybutyl)-2,2′-azobisisobutyrate, di(3-hydroxybutyl)-2,2′-azobisisobutyrate, di(2-hydroxypropyl)-2,2′-azobisisobutyrate, and di(2-hydroxyethyl)-2,2′-azobisisobutyrate were prepared and used as initiators for the preparation of hydroxyl-terminated polybutadienes (HTPBs) of molecular weight (M?_n) ranging from 2000 to 7500 and functionality between 1.90 and 3.0. The polymers were prepared by free-radical solution polymerization in dioxane and toluene. The polymers obtained were characterized for their molecular weight, hydroxyl number, functionality, and instrinsic viscosity.     

Halogenbenzaldehyde, 3. Mitt.

Zusammenfassung Mittels der Konversion aromatischer Amine in die entsprechenden Benzaldehyde, einer Methode, die vonBeech entwickelt und von uns auf Haloaniline erweitert wurde, werden in einfacher, eleganter Weise zwei Halogenbenzaldehyde dargestellt.2. Mitt.:S. D. Jolad undS. Rajagopal, Naturwiss.48, 645 (1961).     

Vacancy‐Engineered Nanoceria: Enzyme Mimetic Hotspots for the Degradation of Nerve Agents

Organophosphorus‐based nerve agents, such as paraoxon, parathion, and malathion, inhibit acetylcholinesterase, which results in paralysis, respiratory failure, and death. Bacteria are known to use the enzyme phosphotriesterase (PTE) to break down these compounds. In this work, we designed vacancy‐engineered nanoceria (VE CeO₂ NPs) as PTE mimetic hotspots for the rapid degradation of nerve agents. We observed that the hydrolytic effect of the nanomaterial is due to the synergistic activity between both Ce³⁺ and Ce⁴⁺ ions located in the active site‐like hotspots. Furthermore, the catalysis by nanoceria overcomes the product inhibition generally observed for PTE and small molecule‐based PTE mimetics.     

Iron-carbon nanohybrid particles as environmentally benign electrode for supercapacitor

Journal of Solid State Electrochemistry - In this work, we report the synthesis and electrode applications of iron-carbon nanohybrid particles prepared by carbonization of a nanocomposite of FeOOH...     

Polyamides containing arylene sulfone ether linkages

Polyamides containing arylene sulfone ether linkages were synthesized from 4,4′-[sulfonylbis(p-phenyleneoxy)] dibenzoyl chloride (SPCI), 3,3′-[sulfonylbis(p-phenyleneoxy)] dibenzoyl chloride (SMCl), and arylene sulfone ether diamines (SED), by solution and interfacial polymerization techniques. In solution polymerization, the effect of various acid acceptors such as propylene oxide (PO), lithium chloride (LiCl)/lithium hydroxide (LiOH), and triethylamine (TEA) on molecular weight of the polyamides was studied. The effect of methyl substituted and unsubstituted aromatic sulfone ether diamines on molecular weight and thermal properties of polyamides was also studied. The polyamides prepared were characterized by solution viscosity, elemental analysis, thermal gravimetric analysis, differential scanning calorimetry, and x-ray diffraction. Physical and thermal properties of polyamides prepared from SPCl and SED were compared with the polyamides prepared from SMCl and SED.     

Synthesis and characterization of novel polybenzimidazoles bearing pendant phenoxyamine groups

A novel aromatic diacid, 3, 5‐dicarboxyl‐4′‐amino diphenyl ether, containing pendant phenoxy amine group was synthesized. Homo‐ and co‐polybenzimidazoles containing different content of pendant phenoxyamine groups were synthesized by condensation of 3,3′‐diaminobenzidine with this acid and a mixture of this acid and isophthalic acid in different ratio in polyphosphoric acid. Copolybenzimidazoles with structural variations were also synthesized based on this acid and pyridine dicarboxylic acid, terephthalic acid, adipic acid, or sebacic acid. The polymers have good solubility in polar aprotic solvents and strong acids and they form tough flexible films by solution casting. The polymers were characterized by different instrumental techniques (FTIR, TGA, DSC, XRD, etc.) and for solvent solubility, mechanical properties, inherent viscosity, and proton conductivity. The inherent viscosities of the polymers vary in the range of 0.62–1.52 dL/g. They have high thermal stability up to 475–506 °C (IDT) in nitrogen, high glass transition temperatures (T_g) ranging from 313 to 435 °C and good tensile strength ranging from 58 to 125 MPa. Proton conductivity of homo polymer is 3.72 × 10^?3 S/cm at 25 °C and 2.45 × 10^?2 S/cm at 200 °C © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5776–5793, 2008     

Syntheses of Branched Non‐1‐ynitols by Chemoselective Addition of (Trimethylsilyl)‐propargylmagnesium Bromide at the Anomeric Center of Side Chain Halogeno Functionalized Carbohydrates

A convenient method for the syntheses of non‐1‐ynitols 8a–8d, by chemoselective addition of (trimethylsilyl)‐propargylmagnesium bromide at the anomeric center of a 1‐unprotected sugar, in the presence of 3‐C′‐halide and 3‐C′‐silyl functions in the side chain is described. In addition, an efficient method for the synthesis of 3‐C′‐hydroxymethyl sugar 3 via the addition of C₁ silyl Grignard reagents to ulose 1 and subsequent oxidation by the Fleming‐Tamao method in excellent yields is reported. Also, a suitable acid‐catalyzed isomerization of the 1,2‐O‐isopropylidene group to the 2,3‐O‐isopropylidene group (5a–5f), to get access to the anomeric center, in good to excellent yields has been depicted.     

Mechanistic investigations on the efficient catalytic decomposition of peroxynitrite by ebselen analogues

In this study, ebselen and its analogues are shown to be catalysts for the decomposition of peroxynitrite (PN). This study suggests that the PN-scavenging ability of selenenyl amides can be enhanced by a suitable substitution at the phenyl ring in ebselen. Detailed mechanistic studies on the reactivity of ebselen and its analogues towards PN reveal that these compounds react directly with PN to generate highly unstable selenoxides that undergo a rapid hydrolysis to produce the corresponding seleninic acids. The selenoxides interact with nitrite more effectively than the corresponding seleninic acids to produce nitrate with the regeneration of the selenenyl amides. Therefore, the amount of nitrate formed in the reactions mainly depends on the stability of the selenoxides. Interestingly, substitution of an oxazoline moiety on the phenyl ring stabilizes the selenoxide, and therefore, enhances the isomerization of PN to nitrate.