KF/La2O2CO3固体碱的制备、表征及催化酯交换反应的性能——一个综合创新实验

固体碱催化剂具有易分离、可循环使用、对设备无腐蚀、可使反应工艺过程连续化等优点。它被认为是催化酯交换反应制备可再生能源生物柴油的一种优异催化剂。本实验是在科研成果的基础上创新设计了一个综合实验。通过浸渍法制备了KF/La2O2CO3固体碱催化剂;利用X射线衍射测定了其物相,使用CO2程序升温脱附技术测定了催化剂的表面碱性;并以三丁酸甘油酯与甲醇进行酯交换反应作为模型反应,考查其催化活性。     

An Infrared Spectroscopic Study of Crystalline Copper (II) Propionate and Butyrate

Abstract

Abstract: The vibrational spectra of crystalline anhydrous copper (II) propionate and butyrate were studied by FT-IR spectroscopy. A detailed assignment of the spectra of both compounds is presented and discussed. It is shown that the presence of two non-equivalent sets of carboxylate ligands within the crystals gives rise to several band splittings, which are particularly evident in those bands ascribable to normal modes involving predominantly the -C_βH₃ or -C_βH₂-fragments. In addition, the vibrational assignments made for the studied molecules are shown to be very useful to help understanding the much more complex spectra of long chain copper carboxylates.     

Spectroscopic study and antioxidant properties of the inclusion complexes of rosmarinic acid with natural and derivative cyclodextrins

Measurement of total antioxidant activity/capacity of polyphenols in various solvent media necessitates the use of cyclodextrins to solubilize lipophilic antioxidants of poor aqueous solubility. The inclusion complexes of the slightly water soluble antioxidant, rosmarinic acid (RA), with α-cyclodextrin (α-CD), β-cyclodextrin (β-CD), 2-hydroxypropyl-β-cyclodextrin (HP-β-CD), 2-hydroxyethyl-β-cyclodextrin (HE-β-CD), and methyl-β-cyclodextrin (M-β-CD) were investigated for the first time. The effect of cyclodextrins (CDs) on the spectral features of RA was measured in aqueous medium using UV-vis and steady-state fluorescence techniques by varying the concentrations of CDs. The molar stoichiometry of RA-CD inclusion complexes was verified as 1:1, and the formation constants of the complexes were determined from Benesi-Hildebrand equation using fluorescence spectroscopic data. Among the CDs, maximum inclusion ability was measured in the case of M-β-CD followed by HP-β-CD, HE-β-CD, β-CD and α-CD. Solid inclusion complexes were prepared by freeze drying, and their functional groups were analyzed by IR spectroscopy. Antioxidant capacity of CD-complexed rosmarinic acid was measured to be higher than that of the lone hydroxycinnamic acid by the CUPric Reducing Antioxidant Capacity (CUPRAC) method. The mechanism of the TAC increase was interpreted as the stabilization of the 1-e oxidized o-catechol moiety of RA by enhanced intramolecular H-bonding in a hydrophobic environment provided by CDs, mostly by M-β-CD.     

官能化二硫缩烯酮的选择性α-溴代反应

发展了一种适用范围广、高效且高选择性的官能化二硫缩烯酮的α-溴代反应.在少量水存在下,在四氢呋喃溶液中,以溴化铜为溴代试剂,经由官能化二硫缩烯酮(1)的α-溴代反应制备了结构多样的α-溴代二硫缩烯酮(2).     

Oxidative aromatization of Hantzsch 1,4-dihydropyridines by cupric bromide under mild heterogeneous condition

A mild heterogeneous oxidizing agent, cupric bromide has been utilized for the oxidative aromatization of Hantzsch 1,4-dihydropyridines to the corresponding pyridine derivatives in excellent yields with the isolation of products by simple work-up procedure.     

Characterization of New Titanium Oxide Polymer Hybrid Membranes for Biofilm Formation

Abstract

Presently, there is great need to create new matrices for diverse applications particularly in the fields of biotechnology and food industry. Here, we report on the synthesis of new matrices based on a mixture of polymer cellulose acetate butyrate/copolymer polyacrylonitrile acrylamide/TiO₂. The characterization of the new matrices was performed using IR spectroscopy, QCM technology, and SEM. The tests revealed that when we use our polymers as carriers, there is a limit for the concentration of titanium of 5%. Further increasing of Ti concentration leads to precipitation processes. The QCM analyses show that a low concentration of Ti(OBu)₄ does not influence the viscosity of the matrices obtained, but their elasticity changes significantly. The membranes obtained were successfully applied for biofilm formation of Yeast strain Saccharomyces cerevisiae.     

From 2-D CuO nanosheets to 3-D hollow nanospheres: interface-assisted synthesis, surface photovoltage properties and photocatalytic activity

CuO hierarchical hollow nanostructures, assembled by nanosheets, were successfully prepared in n-octanol/aqueous liquid system through a microwave approach. Controlled experiments revealed that both bubble and interface play key roles in determining the self-assembly process of CuO hierarchical hollow nanostructures, and the morphology/size of building blocks and final products could be readily tuned by adjusting reaction parameters. Furthermore, a self-assembly mechanism of aggregation-then-growth process through bubble template was proposed for the formation of the hollow hierarchical architectures. Photocatalytic performance evidenced that the obtained CuO hierarchical hollow nanostructures possessed superior photocatalytic efficiency on RhB than that of non-hollow nanostructures, which could be easily demonstrated by SPS response about the separation and recombination situation of photogenerated charges.     

Volumetric and conductometric studies on the interactions of dipeptides with sodium acetate and sodium butyrate in aqueous solutions at T = 298.15 K

Densities and conductivity data for the sodium carboxylate (sodium acetate and sodium butyrate)–dipeptides {(glycyl-l-glutamine and l-alanyl-l-glutamine) + water} systems were determined at T = 298.15 K. The apparent molar volumes of the peptides and the molar conductivity (Λ) of sodium acetate and sodium butyrate have been calculated. These data have been utilized to deduce the standard partial molar volumes (), standard partial molar volumes of transfer for dipeptide from water to aqueous sodium carboxylate solutions (Δ_tV^°), volumetric interaction coefficient, the limiting molar conductivity (Λ_°), and Walden product (Λ_°η). Both and Δ_tV^° for the dipeptides increase with increasing concentration of sodium carboxylate. The interpretation is that this result arises from the dominant interactions of the sodium carboxylate with the charged group and polar groups of peptides. The decrease in Λ_° of sodium carboxylate with increasing dipeptide concentration and nonconstant Walden product are attributed to the interactions of sodium carboxylate with peptide and friction resistance of the solvent medium.     

Determination of linear aliphatic aldehydes in heavy metal containing waters by high-performance liquid chromatography using 2,4-dinitrophenylhydrazine derivatization

A simple and sensitive method is described for the determination of picomolar amounts of C₁–C₉ linear aliphatic aldehydes in waters containing heavy metal ions. In this method, aldehydes were first derivatized with 2,4-dinitrophenylhydrazine (DNPH) at optimized pH 1.8 for 30 min and analyzed by HPLC with UV detector at 365 nm. Factors affecting the derivatization reaction of aldehydes and DNPH were investigated. Cupric ion, an example of heavy metals, is a common oxidative reagent, which may oxidize DNPH and greatly interfere with the determination of aldehydes. EDTA was used to effectively mask the interferences by heavy metal ions. The method detection limits for direct injection of derivatized most aldehydes except formaldehyde were of the order of 7–28 nM. The detection limit can be further lowered by using off-line C₁₈ adsorption cartridge enrichment. The recoveries of C₁–C₉ aldehydes were 93–115% with a relative standard deviation of 3.6–8.1% at the 0.1 μM level for aldehydes. The HPLC–DNPH method has been applied for determining aldehyde photoproducts from Cu(II)–amino acid complex systems.