Synthesis and characterization of copolymers of dialkyl fumarates

Radical copolymerisations of di-iso-propyl fumarate (DiPF) with di-n-propyl fumarate (DnPF), di-n-butyl fumarate (DnBF), di-n-amyl-fumarate (DnAF), di-n-heptyl fumarate (DnHF) and di-ethyl-hexyl fumarate (DEHF) were studied. The reactivity ratios for the following monomer pairs, DiPF/DnPF, DiPF/DnBF, DiPF/DnAF, DiPF/DnHF and DiPF/DEHF, were determined. The structures of the copolymers were examined by H-1-NMR and WAXD. Some properties of the copolymers were examined.

Barrier properties of vinylidene chloride copolymers

The permeability coefficients of a series of copolymers of vinylidene chloride (VDC) with methyl acrylate (MA), butyl acrylate (BA) or vinyl chloride (VC) (as comonomer) to oxygen and carbon dioxide have been measured at 1.0 MPa and 30 degrees C, while those to water vapor have been measured at 30 degrees C and 100% relative humidity. All the copolymers are semicrystalline. VDC/MA copolymers have lower melting temperature compared with VDC/BA copolymers, while that melting temperature of VDC/VC copolymer is higher than that of VDC/acrylate copolymers with the same VDC content. The barrier property of the copolymers is predominantly controlled by crystallite, free volume fraction, and cohesive energy. The permeability coefficients of VDC/MA copolymers to oxygen, carbon dioxide, and water vapor were successfully correlated with the ratio of free volume to cohesive energy.

An ESR study on (OH)-O-center dot-radical scavenging activity of water-soluble fullerenols

Water-soluble polyhydroxylated fullerene derivatives (fullerenol) were synthesized, and their scavenging ability for (OH)-O-.-radical was studied by the combination of ESR spectroscopy and spin-trapping technique with phenyl-t-butyl-nitrone. It was found that fullerenols showed an excellent efficiency in eliminating (OH)-O-. free radicals generated by UV photolysis of H2O2. At an applied fullerenol concentration of 0, 3 mg/mL in the final solution, a radical scavenging efficiency of approximate 95% was achieved, revealing the potential use of these compounds as novel potent free radical scavengers in biological systems.

STUDIES ON INCREASING THE ACTIVITY OF SELENIUM-CONTAINING ABZYME .1. SYNTHESIS, CHARACTERIZATION AND PROPERTIES OF HAPTEN AND ANTIGEN

The thiol group of glutathione (GSH) reacts specifically with 2,4-di-ni-trochlorobenzene to give S-substituted dinitrophenyl glutathione (GSH-S-DNP); two carboxyl groups of GSH-S-DNP were further esterified by n-butanol to produce the hapten, multisubstrate analog GSH-S-DNP Butyl Ester (GSH-S-DNP BE). The primary structure of the hapten was characterized by the free. amino group analysis, H-1 NMR, IR determinations and the elemental analysis. The hapten was then conjugated to bovine serum albumin (BSA) in the presence of glutaraldehyde. The reaction mixture was purified by Ultrogel AcA54 colum chromatography to give the antigen. On an average, 25 haptens were bound to each BSA molecule. Electrophoresis analysis showed that the average molecular weight of the antigen was 87 KD. CD spectrum showed that the a-helix content of the antigen increased.

RING-OPENING POLYMERIZATION OF TETRAHYDROFURAN WITH RARE EARTH-CONTAINED CATALYSTS

Rare earth trifluoroacetates, Ln(CF3CO2)(3) (Ln = thirteen rare earth elements), combined with R(n)AlH(3-n) (R = methyl, octyl, n = 3; R = ethyl, i-Butyl, n = 2, 3) were used as catalysts for the polymerization of tetrahydrofuran (THF). The activity increased by adding propylene oxide (PO), as a promoter, to the polymerization system, producing high molecular weight polytetrahydrofuran (PTHF). The effects of Ln, PO/Ln, and Al/Ln, and others on the polymerization of THF were also studied. (C) 1993 John Wiley & Sons, Inc.

THE CATALYTIC ACTIVITY OF HETEROPOLY ACIDS (SALTS) AND MONO-LACUNARY HETEROPOLY TUNGSTOPHOSPHORIC COMPOUND IN THE OXIDATION OF ALCOHOLS

The catalytic activity of heteropoly compounds in the oxidation of benzyl alcohol and cyclohexa nol under phase transfer conditions has been studied. The catalytic activity of six kinds of heteropoly acids with Keggin structure will drop by the order of GeMo12 (H4GeMo12O40). PW12, PMo12, SiMo12, GeW12 and SiW12. When the three protons of H3PW12O40 Were replaced by Na+ step by step, the catalytic activity will raise gradually with the drop of acidity. The addition of base and trace amount of sulfuric acid to the reaction system resulted in an increase of catalytic activity. It was found that catalytic activity of mono-lacunary heteropoly compounds is higher than that of the primary heteropoly acids (or salts). The catalytic oxidation system of HPA-H2O2-PTC is very active in the oxidation of benzyl alcohol ana cyclohexanol, but it has little activity in the oxidation of inactive compounds such as n(or iso)-proplalcohol. n-butyl alcohol and n-hexanol. Solvent has great effect on reaction, when polar compounds such as water were used as solvent, the catalytic activity is better than that when non-polar compounds were used as solvent.

STRUCTURES AND PROPERTIES OF DIALKYL FUMARATES POLYMERS

Polymers of methyl-iso-propyl fumarate, di-iso-propyl fumarate, di-t-butyl fumarate, di-s-butyl fumarate, di-s-amyl fumarate and di-cyclo-hexyl fumarate were prepared by radical polymerization. The structures of the polymers were examined by H-1-NMR, C-13-NMR and WAXD. Some properties of the polymers, including thermal properties, were examined.

SYNTHESIS AND X-RAY CRYSTAL-STRUCTURE OF AN ORGANOLANTHANIDE COMPLEX [(BU(T)CP)3NDBRLI(THF)3]

(ButCp)2NdCl.2THF reacts with one equivalent of phenyllithum in THF yielding tris(tert-butylcyclopentadienyl)neodymium lithium bromide tetrahydrofuran, [(ButCP)3 NdBrLi(THF)3], as a by-product, whose structure has been determined by X-ray crystallography. The 10-coordinated neodymium atom is bonded to three tert-butyl-cyclopentadienyl groups and one bromine atom, forming a distorted pseudo-tetrahedron.

STUDIES ON ELECTROGENERATION, INSITU ELECTROCHEMISTRY AND SPECTROELECTROCHEMISTRY OF ALKYL COBALT PORPHYRIN

Methyl-, ethyl-, propyl- and n-butyl cobalt porphyrins were electrochemically synthesized and studied byIn-situ cyclic voltammetry and UV-Visible spectro-el ectrochemistry. Rate constants for the alkylations were determined. It was found that the four alkyl saturated tetraphenylchlorin cobalt complexes were formed after electrochemical reduction of the alkyl cobalt porphyrins.

DIELS-ALDER REACTION CATALYZED BY RARE-EARTH CHLORIDES

Rare earth chlorides were used to catalyze the synthesis of 2-butoxy-3, 4-dihydro-2H-pyran using equimolar acrolein and vinyl butyl either. The cycloadduct is unstable which undergoes catalytic ring opening oligomerization. The way to stabilize the cyclo adduct has been studied, thus high yields of 90-95% were obtained.

Natural bromophenols from the marine red alga Polysiphonia urceolata (Rhodomelaceae): Structural elucidation and DPPH radical-scavenging activity

Three new natural occurring bromophenols, 3-(3-bromo-4,5-dihydroxyphenyl)-2-(3,5-dibromo-4-hydroxyphenyl)propionic acid (1), (E)-4-(3-bromo-4,5-dihydroxyphenyl)-but-3-en-2-one (2), and (3,5-dibromo-4-hydroxyphenyl) acetic acid butyl ester (3), together with one known bromophenol, 1,2-bis(3-bromo-4,5-dihydroxyphenyl)ethane (4), were isolated and identified from the marine red alga Polysiphonia urceolata. The structures of these compounds were elucidated by extensive analysis of ID and 2D NMR and IR spectra and MS data. Each of the isolated compounds was evaluated for scavenging alpha,alpha-diphenyl-beta-picrylhydrazyl (DPPH) radical activity and all of them exhibited significant activity with IC50 values ranging from 9.67 to 21.90 mu M, compared to the positive control, a well-known antioxidant butylated hydroxytoluene (BHT), with IC50 83.84 mu M. (C) 2007 Elsevier Ltd. All rights reserved.

Gas chromatographic enantiomer separation on single and mixed cyclodextrin derivative chiral stationary phases

Capillary gas chromatographic enantiomer separation of some polar compounds, including alpha-phenylethylamine, styrene oxide, pyrethroid insecticides and other carboxylates, was investigated on modified cyclodextrin (CD) chiral stationary phases. The chiral stationary phases studied included permethylated beta-CD (PMBCD), heptakis (2,6-di-O-butyl-3-O-butyryl)-beta-CD (DBBBCD), heptakis (2,6-di-O-nonyl-3-O-trifluoroacetyl)-beta-CD (DNTBCD), the mixture of PMBCD and DBBBCD, and the mixture of PMBCD and DNTBCD. On the mixed chiral stationary phases containing the mixtures of derivatized cyclodextrins, enantiomer separation was improved significantly for some compounds as compared to the single cyclodextrin derivative chiral stationary phases, and synergistic effects were observed for some compounds on the mixed cyclodextrin derivative chiral stationary phases.

Epoxidation of styrene on Si/Ti/SiO2 catalysts prepared by chemical grafting

Titania-silica (Ti/SiO2) and silica-titania-silica (Si/Ti/SiO2) catalysts were:prepared by chemical grafting using TiCl4 and tetraethyl orthosilicate (TEOS) as precursors and SiO2 as support. The prepared catalysts were characterized by UV Raman and visible Raman spectroscopies, XRD and the epoxidation of styrene; Ti/SiO2: catalyst grafted with only titanium species is not very active for epoxidation using H2O2 (30%), but is active and-selective when one uses tert-butyl hydroperoxide (TBHP). The catalyst grafted at high temperatures shows better epoxide selectivity. Si/Ti/SiO2 catalyst, the titanium-silica grafted further with TEOS, is active and selective for the epoxidation of styrene using either dilute H2O2 or TBHP, possibly due to the fact that the grafting of Ti/SiO2 with TEOS modifies the coordination structure of titanium and makes the titanium sites of Si-O-Ti-O-Si species less hydrophilic. A characteristic band at 1085cm(-1) due to Ti-O-Si species is detected for the grafted catalysts by UV resonance Raman spectroscopy. Reaction between TiCl4 and SiO2 at high temperatures favors the formation of Ti-O-Si species. Better activity and selectivity to epoxide,is found for the catalysts with more Ti-O-Si species. It is assumed that the active sites are the highly isolated Ti-O-Si species. For Si/Ti/SiO2 catalyst, the gas phase O-2 can participate in the catalytic oxidation of styrene when H2O2 is present ana:ii causes the formation of benzaldehyde. (C) 2000 Elsevier Science B.V. All rights reserved.

Purification and characterization of recombinant truncated human interleukin-11 expressed as fusion protein in Escherichia coli

Mature human interleukin-11 (HuIL-11) is a cytokine consisting of 178 amino acid residues that results from scission of the N-terminal signal peptide, consisting of 21 amino acid residaues, from the corresponding nascent polypeptide. A DNA fragment encoding a truncated HuIL-11 (trHuIL-11), with an additional 5 amino acid residues removed from the N-terminus, was cloned into vector pGEX-2T between the BamHI site and the EcoRI site. Upon transformation with Escherichia coli BL21, the construct over-produced a glutathione S-transferase (GST)-fused protein in a soluble form after IPTG induction. The fusion protein was initially fractionated with butyl-Sepharose 4 fast flow column and by affinity chromatography using a GSH-Sepharose 4B column. On-site enzymatic release with thrombin gave the target protein at 96% purity as judged by SDS-PAGE and HPLC. Expression of the interleukin as a GST-fused protein thus greatly improved downstream processing. Subsequent biological activity assay suggested that trHuIL-11 had similar activity profile to the naturally produced sample and may be a promising candidate for further development as biopharmaceutical.