An Efficient Approach to Chiral Ferrocene‐Based Secondary Alcohols via Asymmetric Hydrogenation of Ferrocenyl Ketones

P‐Phos‐ruthenium‐DPEN precatalysts have been found to be efficient for the asymmetric hydrogenation of various ferrocenyl ketones. The use of (R)‐xylyl‐P‐PhosRuCl₂(R,R)‐DPEN generated chiral ferrocenylethanol in 99.3% e.e. with >99% conversion in a 150‐g scale.     

An Amine‐, Copper‐ and Phosphine‐Free Sonogashira Coupling Reaction Catalyzed by Immobilization of Palladium in Organic–Inorganic Hybrid Materials

An immobilization of palladium in organic‐inorganic hybrid materials‐catalyzed Sonogashira coupling reaction has been described. Terminal alkynes reacted with aryl iodides and aryl bromides only in the presence of a 3‐(2‐aminoethylamino)propyl‐functionalized, silica gel‐immobilized palladium catalyst under amine‐, copper‐ and phosphine‐free reaction conditions. The reaction generates the corresponding cross‐coupling products in excellent yields. Furthermore, the silica‐supported palladium can be recovered and recycled by a simple filtration of the reaction solution and used for 30 consecutive trials without any decreases in activity.     

STUDY ON PERMEATION OF ACETONE/NITROGEN MIXED GAS THROUGH AL2O3 MICROPOROUS MEMBRANES: MOLECULAR DYNAMICS

In this work, by applying Materials Studio 2.2 software package, molecular dynamics (MD) was performed to investigate the dynamic processes of 1:4 acetone/nitrogen mixed gas permeating through different Al₂O₃ microporous membranes. Three systems were modeled by considering different box lengths, microporous sizes, and textures of Al₂O₃ membranes to compare different permeation behaviors. In each system, initial mixed gas contained 20 acetone molecules and 80 nitrogen molecules, and its density was set to 0.1 g/cm³. Analysis on the concentration profiles of nitrogen molecules (N2) and acetone molecules (Ace) in each system at different sampling times was implemented to discuss the permeation behaviors of smaller N2 and larger Ace. The results showed that adsorption and diffusion occurred synchronously but adsorption was dominant for acetone molecules and that the adsorption on the floor surface of the feed gas region more easily reached equilibrium (local equilibrium) than the diffusion and the adsorption on the ceiling of the initially vacuum region. Furthermore, for nitrogen, adsorption followed diffusion. Higher temperature is in favor of the enrichment of acetone on the floor surface of the feed gas region but against the adsorption of nitrogen. The adsorptive layer was found to be a double-layer with COMPASS force field and to be a monolayer with PCFF force field.     

Study of Structure-property Relationships of Poly(benzobisthiazole) and it’s Derivatives

Summary Poly(p-phenylene benzobisthiazole) (PBZT) and a series of new derivatives, poly(benzobisthiazole-1,4-diphenylene etherylene) (PBTPE), poly(bisbenzothiazole-2,2’-phenelyene-6,6’-(4-tert-butyl)cyclohexylidene) (PBTPBCH) and poly(bisbenzothiazole-2,2’-phenelyene etherylene-6,6’-(4-tert-butyl)cyclohexylidene) (PBTPEBCH), were synthesized by polycondensation of 2,5-diamino-1,4-benzenedithiol dihydrochloride (DABDT·2HCl) or 1,1-bis(4-amino-3-mercaptophenyl)-4-tert-butylcyclohexane dihydrochloride (BAMPBCH·2HCl) with terephthalic acid or 4,4’-dicarboxydiphenyl ether in poly (phosphoric acid) (PPA). The inherent viscosity, thermal stability, solubility, morphology and photophysical properties of them were investigated and compared in detail. The introduction of etherylene or 4-tert-butylcyclohexylidene both decreased the inherent viscosity of PBZT. Although the decomposition temperatures of these derivatives were lower than PBZT, they still had good thermal stability. In addition, the thermogravimetric analysis showed PBTPBCH and PBTPEBCH containing 4-tert-butylcyclohexylidene had the lower thermal stability than PBTPE containing etherylene. The solubility of them was all enhanced. Especially, PBTPBCH and PBTPEBCH showed better solubility. X-ray diffractograms of all the derivatives showed that they were amorphous. Compared with PBZT, the absorption maximum (λ_max) of all the derivatives prepared was blue shifted in different degree according to their structure respectively. The excitation and emission peaks were also blue shifted. Furthermore, both of the substituting groups incorporated into the polymer backbone could improve the photoluminescence quantum yield to a certain extent. Finally we established the structure-property relationships of this class of poly(benzothiazole)s by investigating and comparing these properties in detail.     

Preliminary investigation of poly(ether sulfone)/poly(aryl ether ketone) containing 1,4‐naphthalene blends

The blends of poly(ether sulfone) and poly(aryl ether ketone) containing 1,4‐naphthalene were prepared by melt mixing in a Brabender‐like apparatus. The specimens for measurements were made by compression molding under pressure and then were water‐quenched at room temperature. The tensile strength, tensile modulus, elongation at break, thermal analysis, and scanning electron microscopy were each measured. The dependence of tensile strength, tensile modulus, and elongation at break on blend systems was obtained. The effects of composition and miscibility on the mechanical properties are discussed. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 472–476, 2006     

Investigation of Scale Formation in Heat Exchangers of Phosphoric Acid Evaporator Plants

The primary problem in concentrating phosphoric acid is due to fouling on the tube‐side of the heat exchangers of the evaporator units. Scaling on the heat transfer surfaces occurs because of high supersaturation of phosphoric acid liquor with respect to calcium sulphate. A review of the existing literature reveals that no information is available on heat transfer and on crystallization fouling of industrial phosphoric acid solutions. In this investigation, the solubility of different calcium sulphate types in phosphoric acid solution was studied and its dependency on acid concentration and temperature was investigated. A large number of fouling experiments were carried out in a side‐stream of a phosphoric acid plant at different flow velocities, surface temperatures and concentrations to determine the mechanisms, which control the deposition process. After identifying the effects of operational parameters on the deposition process, a model was developed for prediction of fouling resistances. The reaction of calcium sulphate crystallization followed a second order rate with respect to the supersaturation. The activation energy evaluated for the surface reaction of the deposit formation was found to be 57 kJ/mol. The predicted fouling resistances were compared with the experimental data. Quantitative and qualitative agreement between measured and predicted fouling rates is good.     

Studies on crystal morphology and crystallization kinetics of polypropylene filled with CaCO3 of different size and size distribution

Changes in the crystal morphology, crystallinity, and the melting temperature of thermoplastics resulted in significant changes in the mechanical behavior of composites containing them. For this reason, the research of crystal morphology and crystallization kinetics in thermoplastic composites became an important requirement. The thermoplastic filled with the filler of different size gradation was a new method for improving processability of thermoplastic composites. We have previously reported that the melt viscosity of polypropylene (PP) composites, which were filled with 30 wt % CaCO₃ of effective size gradation, could be evidently declined. In this study, two sizes of CaCO₃, 325 meshes and 1500 meshes, were blended by different proportions and filled into PP matrix with 30 wt %. Crystal morphology and isothermal crystallization kinetics of a series of composites were characterized by differential scanning calorimeter (DSC) and polarizing microscope. The results showed that composites filled with CaCO₃ of effective size gradation leaded to a well‐crystalline order and a large crystal size, while their isothermal crystallization kinetics and crystallization rate constant (k) were declined, and their Avrami exponents (n) and crystallization half‐life (t_1/2) were increased compared with the composites filled with single size CaCO₃. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2437–2444, 2006     

Enhanced Cometabolic Transformation of 4‐Chlorophenol in the Presence of Phenol by Granular Activated Carbon Adsorption

Substrate inhibitions that manifest within the cometabolism system of 4‐chlorophenol (4‐cp) and phenol were alleviated through the application of granular activated carbon (GAC) in batch biodegradation. It was found that 4‐cp was preferentially adsorbed over phenol by the GAC and that 50% to 70% of the adsorption was achieved within the first two hours of contact. The kinetics of 4‐cp adsorption was also much faster than that of phenol, even when the co‐existing phenol was of a significantly higher initial concentration. As a result, competitive inhibition between the two compounds was minimized. Adsorption also caused a lowering of the phenol concentration in solution with a concomitant reduction in the substrate inhibition effect on cell growth. The addition of GAC benefited the biotransformation process through shortening the total degradation time for 600 mg L^?1 phenol and 100 mg L^?1 4‐cp from 42 h to 12 h; and it also made it possible for cells to survive and transform 600 mg L^?1 phenol and as high as 400 mg L^?1 4‐cp in free suspension cultures. Repeated operations in which GAC was reused showed that GAC could be regenerated by the cells, thus rendering the GAC incorporated process amenable to long term operations.     

Characterization and comparison of diblock and triblock amphiphilic copolymers of poly(δ‐valerolactone)

Three types of pegylated amphiphilic copolymers of poly(δ‐valerolactone) (PVL) were copolymerized with methoxy poly(ethylene glycol) (MePEG) and poly(ethylene glycol) (PEG₄₀₀₀ and PEG_10,000), respectively. Pegylation of PVL allowed copolymers possessing amphiphilic property and efficiently self‐assembled to form micelles with a low critical micelle concentration (CMC) in the range of 10^?7–10^?8M. The average molecular weight of copolymers was in the range of 10,000–20,000 Da, and the polydispersity of copolymers was about 1.7–1.8. Higher mobility of low molecular weight PEG (i.e., MePEG and PEG₄₀₀₀) than high molecular weight PEG_10,000 allowed valerolactone ring opening more efficient in terms of PVL/MePEG and PVL/PEG₄₀₀₀ copolymers possessing longer chain length in hydrophobic domain. Pegylated PVL with low CMC and triblock structure was preferred to encapsulate drug during micelle formation. Although all of these amphiphilic copolymers exhibited controlled release character, the micelles formed by triblock copolymer possessed a more stable core‐shell conformation than that by diblock copolymer, and resulted in the release of drug from triblock micelles slower than that from diblock micelles. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1836–1841, 2006     

Solubility of Propane in Sulpholane at Elevated Pressures

The solubility of propane in sulpholane has been determined at temperatures in the range 298‐403 K at pressures up to 17.6 MPa. The experimental results were correlated by the Peng‐Robinson equation of state, and binary interaction parameters have been obtained for this system. The parameters in the Krichevsky‐Ilinskaya equation were calculated from these interaction parameters.