scholarly journals The Effect of Titanium Tetra-Butoxide Catalyst on the Olefin Polymerization

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2109
Author(s):  
Mohammed S. Alsuhybani ◽  
Eid M. Alosime
Keyword(s):  
Chain Transfer ◽  
Synergistic Effects ◽  
Average Molecular Weight ◽  
Organic Polymer ◽  
Molar Ratio ◽  
Initial Activity ◽  
Titanium Butoxide ◽  
Catalytic Activities ◽  
Rate Of Reaction ◽  
Aluminum Alkyls

The purpose of this study was to assess the ability of titanium Ti(IV) alkyloxy compounds supported by organic polymer polyvinyl chloride (PVC) to polymerize ethylene by feeding triethylaluminium (TEA) as a cocatalyst. Additionally, the impacts of the molar ratio of [Al]/[Ti] on the catalytic activities in ethylene’s polymerization and of the comonomer through utilization of diverse quantities of comonomers on a similar or identical activity were studied. The optimal molar ratio of [Al]/[Ti] was 773:1, and the prepared catalyst had an initial activity of up to 2.3 kg PE/mol Ti. h. when the copolymer was incorporated with 64 mmol of 1-octene. The average molecular weight (Mw) of the copolymer produced with the catalysts was between 97 kg/mol and 326 kg/mol. A significant decrease in the Mw was observed, and PDI broadened with increasing concentration of 1-hexene because of the comonomer’s stronger chain transfer capacity. The quick deactivation of titanium butoxide Ti(OBu)4 on the polymers was found to be associated with increasing oxidation when supported by the catalyst. The presence of Ti (III) after reduction with the aluminum alkyls cleaves the carbon-chlorine bonds of the polymer, producing an inactive polymeric Ti(IV) complex. The results show that synergistic effects play an important role in enhancing the observed rate of reaction, as illustrated by evidence from scanning electron microscopy (SEM). The diffusion of cocatalysts within catalytic precursor particles may also explain the progression of cobweb structures in the polymer particles.

Metathesis Polymerization of Phenylacetylene by Tungsten Aryloxo Complexes

1995 ◽  
Vol 60 (3) ◽  
pp. 489-497 ◽  
Author(s):  
Hynek Balcar ◽  
Jan Sedláček ◽  
Marta Pacovská ◽  
Vratislav Blechta
Keyword(s):  
Molecular Weight ◽  
Catalytic Activity ◽  
Induction Period ◽  
Average Molecular Weight ◽  
Molar Fraction ◽  
Molar Ratio ◽  
Weight Average Molecular Weight ◽  
Polymer Yield ◽  
Positive Effect ◽  
Ligand Addition

Catalytic activity of the tungsten aryloxo complexes WCl5(OAr) and WOCl3(OAr), where Ar = 4-t-C4H9C6H4, 2,6-(t-C4H9)2C6H3, 2,6-Cl2C6H3, 2,4,6-Cl3C6H2, and 2,4,6-Br3C6H2 in polymerization of phenylacetylene (20 °C, monomer to catalyst molar ratio = 1 000) was studied. The activity of WCl5(OAr) as unicomponent catalysts increases with increasing electron withdrawing character of the -OAr ligand. Addition of two equivalents of organotin cocatalysts (Me4Sn, Bu4Sn, Ph4Sn, Bu3SnH) to WCl5(O-C6H2Cl3-2,4 ,6) has only slight positive effect (slightly higher polymer yield and/or molecular weight of poly(phenylacetylene)s was achieved). However, in the case of WOCl3(O-C6H3Cl2-2, 6) catalyst, it enhances the activity considerably by eliminating the induction period. Poly(phenylacetylene)s prepared with the catalysts studied have weight-average molecular weight ranging from 100 000 to 200 000. They are trans-prevailing and have relatively low molar fraction of monomer units comprised in cyclohexadiene sequences (about 6%).

scholarly journals Efficient alkaloid capture from water using a charged porous organic polymer

RSC Advances ◽  
2018 ◽  
Vol 8 (58) ◽  
pp. 33398-33402 ◽  
Author(s):  
Qing-Mei Zhang ◽  
Zhen Wang ◽  
Guang Cheng ◽  
Hui Ma ◽  
Qing-Pu Zhang ◽  
...  
Keyword(s):  
Adsorption Capacity ◽  
Electrostatic Interaction ◽  
Synergistic Effects ◽  
Porous Polymer ◽  
Organic Polymer ◽  
Berberine Hydrochloride ◽  
Porous Organic Polymer

A charged porous polymer displays excellent adsorption capacity for berberine hydrochloride from the synergistic effects of size matching and electrostatic interaction.

scholarly journals Esterification of palmitic acid with epichlorohydrin on anion exchange resin catalyst

2007 ◽  
Vol 5 (3) ◽  
pp. 715-726 ◽  
Author(s):  
Emil Muresan ◽  
Spiridon Oprea ◽  
Theodor Malutan ◽  
Mihai Vata
Keyword(s):  
Palmitic Acid ◽  
Exchange Resin ◽  
Catalyst Particle ◽  
Molar Ratio ◽  
Catalyst Loading ◽  
Esterification Reaction ◽  
Macroporous Resin ◽  
Resin Catalyst ◽  
Catalyst Particle Size ◽  
Rate Of Reaction

AbstractThe esterification reaction of palmitic acid with epichlorohydrin catalyzed by an anionic macroporous resin was studied. Purolite A-500 resin proved to be a very effective catalyst in the synthesis of 3-chloro-2-hydroxypropyl palmitate. The effects of certain parameters such as speed of agitation, catalyst particle size, catalyst loading, temperature, initial molar ratio between reactants on the rate of reaction were studied. It was found that the overall rate is intrinsically kinetically controlled. The structure of synthesized ester was confirmed by FTIR and 1H NMR analyses.

scholarly journals Oxidation of monohydric phenol substrates by tyrosinase. An oximetric study

1992 ◽  
Vol 288 (1) ◽  
pp. 63-67 ◽  
Author(s):  
S Naish-Byfield ◽  
P A Riley
Keyword(s):  
Oxygen Consumption ◽  
Maximum Rate ◽  
Low Ph ◽  
Molar Ratio ◽  
Lag Phase ◽  
Complete Oxidation ◽  
Mushroom Tyrosinase ◽  
Tyrosine Oxidation ◽  
Rate Of Reaction ◽  
Dopa Oxidase

The purity of commercially available mushroom tyrosinase was investigated by non-denaturing PAGE. Most of the protein in the preparation migrated as a single band under these conditions. This band contained both tyrosinase and dopa oxidase activity. No other activity of either classification was found in the preparation. Oxygen consumption by tyrosinase during oxidation of the monohydric phenol substrates tyrosine and 4-hydroxyanisole (4HA) was monitored by oximetry in order to determine the stoichiometry of the reactions. For complete oxidation, the molar ratio of oxygen: 4HA was 1:1. Under identical conditions, oxidation of tyrosine required 1.5 mol of oxygen/mol of tyrosine. The additional oxygen uptake during tyrosine oxidation is due to the internal cyclization of dopaquinone to form cyclodopa, which undergoes a redox reaction with dopaquinone to form dopachrome and dopa, which is then oxidized by the enzyme, leading to an additional 0.5 mol of oxygen/mol of original substrate. Oxygen consumption for complete oxidation of 200 nmol of 4HA was constant over a range of concentrations of tyrosinase of 33-330 units/ml of substrate. The maximum rate of reaction was directly proportional to the concentration of tyrosinase, whereas the length of the lag phase decreased non-linearly with increasing tyrosinase concentration. Activation of the enzyme by exposure to citrate was not seen, nor was the lag phase abolished by exposure of the enzyme to low pH. Michaelis-Menten analysis of tyrosinase in which the lag phase is abolished by pre-exposure of the enzyme to a low concentration of dithiothreitol gave Km values for tyrosine and 4HA of 153 and 20 microM respectively.

scholarly journals Advances in Nanostructured Metal-Encapsulated Porous Organic-Polymer Composites for Catalyzed Organic Chemical Synthesis

Catalysts ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 492 ◽  
Author(s):  
Wilhemina Sebati ◽  
Suprakas Ray
Keyword(s):  
Binding Sites ◽  
Heterogeneous Catalysts ◽  
Acid Catalysis ◽  
High Surface ◽  
Organic Polymer ◽  
Organic Chemical ◽  
Characterization Methods ◽  
Catalytic Activities ◽  
Surface Areas ◽  
Nanostructured Metal

Porous organic polymers (POPs) are of growing research interest owing to their high surface areas, stabilities, controllable chemical configurations, and tunable pore volumes. The molecular nanoarchitecture of POP provides metal or metal oxide binding sites, which is promising for the development of advanced heterogeneous catalysts. This article highlights the development of numerous kinds of POPs and key achievements to date, including their functionalization and incorporation of nanoparticles into their framework structures, characterization methods that are predominantly in use for POP-based materials, and their applications as catalysts in several reactions. Scientists today are capable of preparing POP-based materials that show good selectivity, activity, durability, and recoverability, which can help overcome many of the current environmental and industrial problems. These POP-based materials exhibit enhanced catalytic activities for diverse reactions, including coupling, hydrogenation, and acid catalysis.

scholarly journals Physicochemical Characterization and Immunomodulatory Activity of a Novel Acid Polysaccharide from Solanum muricatum

Polymers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 1972 ◽  
Author(s):  
Heng Yue ◽  
Qianqian Xu ◽  
Xianheng Li ◽  
Jeevithan Elango ◽  
Wenhui Wu ◽  
...  
Keyword(s):  
High Performance ◽  
Average Molecular Weight ◽  
Thermal Studies ◽  
Physicochemical Characterization ◽  
Monosaccharide Composition ◽  
Molar Ratio ◽  
Immunomodulatory Activity ◽  
Composition Analysis ◽  
Solanum Muricatum ◽  
Acid Polysaccharide

To investigate the structure and immunomodulatory activity of polysaccharide from Solanum muricatum, a novel acid polysaccharide named SMP-3a was purified from Solanum muricatum pulp through DEAE-52 cellulose column and Sephadex G-200 chromatography. Monosaccharide composition analysis showed that SMP-3a was mainly composed of rhamnose, arabinose, galactose, and galacturonic acid with the molar ratio of 1.09:2.64:1.54:1. The average molecular weight was found to be 227 kDa by high performance gel permeation chromatography (HPGPC). Thermal studies revealed the SMP-3a was a thermally stable polymer. Based on the results of methylation and NMR analysis, the backbone chain of SMP-3a was composed of →2)-α-l-Rhap-(1→, →4)-α-d-GalpA-(1→ and →4)-α-d-Galp-(1→. The side chain was consisted of α-l-Araf-(1→ and →5)-α-l-Araf-(1→. Immunomodulatory assay indicated that SMP-3a could significantly promote the proliferation of macrophages and stimulate the secretion of cytokines, including TNF-α, IL-1β, and IL-6. Our results suggested that SMP-3a could be used as a novel potential immunomodulatory agent in functional food.

An indole-derived porous organic polymer for the efficient visual colorimetric capture of iodine in aqueous media via the synergistic effects of cation–π and electrostatic forces

2020 ◽  
Vol 56 (9) ◽  
pp. 1401-1404 ◽  
Author(s):  
Min Huang ◽  
Li Yang ◽  
Xiuyun Li ◽  
Guanjun Chang
Keyword(s):  
Electrostatic Interactions ◽  
Synergistic Effects ◽  
Aqueous Media ◽  
Organic Polymer ◽  
Electrostatic Forces ◽  
Porous Organic Polymer

A recyclable indole-based POP was successfully achieved, which was capable of visual colorimetric iodine capture in water via cation–π and electrostatic interactions.

scholarly journals Cr-Phthalocyanine Porous Organic Polymer as an Efficient and Selective Catalyst for Mono Carbonylation of Epoxides to Lactones

Catalysts ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 905
Author(s):  
Vinothkumar Ganesan ◽  
Sungho Yoon
Keyword(s):  
Lewis Acid ◽  
Design Strategy ◽  
Organic Polymer ◽  
Acid Base ◽  
One Pot ◽  
Selective Catalyst ◽  
Catalytic Activities ◽  
Porous Organic Polymer ◽  
Polymeric Catalyst ◽  
Highly Porous

A facile, one-pot design strategy to construct chromium(III)-phthalocyanine chlorides (Pc’CrCl) to form porous organic polymer (POP-Pc’CrCl) using solvent knitting Friedel-Crafts reaction (FCR) is described. The generated highly porous POP-Pc’CrCl is functionalized by post-synthetic exchange reaction with nucleophilic cobaltate ions to provide an heterogenized carbonylation catalyst (POP-Pc’CrCo(CO)4) with Lewis acid-base type bimetallic units. The produced porous polymeric catalyst is identical to that homogeneous counterpart in structure and coordination environments. The catalyst is very selective and effective for mono carbonylation of epoxide into corresponding lactone and the activities are comparable to those observed for a homogeneous Pc’CrCo(CO)4 catalyst. The (POP-Pc’CrCo(CO)4) also displayed a good catalytic activities and recyclability upon successive recycles.

Kinetics and Modelling of Bulk and Solution Diallyl Terephthalate Polymerization

2006 ◽  
Vol 4 (1) ◽  
Author(s):  
Iztok Hace
Keyword(s):  
Kinetic Model ◽  
Kinetic Parameters ◽  
Rate Constants ◽  
Chain Transfer ◽  
Average Molecular Weight ◽  
Propagation Rate ◽  
Reaction Conditions ◽  
Diffusion Limitations ◽  
Kinetics Of ◽  
Dicyclohexyl Peroxydicarbonate

Free radical polymerization kinetics of diallyl terephthalate (DAT) in solution was investigated with two different peroxide initiators: dicyclohexyl peroxydicarbonate (CHPC) and benzoyl peroxide (BPO) in temperature range from 50°C to 110°C, where ortho-xylene was used as a solvent. Conversion points were measured using Fourier Transform Infrared (FTIR) measurements. Previously developed kinetic model for bulk DAT polymerization, was extended to solution DAT polymerization. The ratio of solvent chain - transfer rate constants to propagation rate constants of the polymerization system were found between 1.25 10-4 to 1.68 10-4 for various reaction conditions. They were obtained using the calculated initial polymerization rates and the number average molecular weight measurements made by GPC. The effect of different solvent fractions and initiator concentrations on the diffusion limitations were investigated. Only two kinetic parameters, kpd0 and ktd0 were obtained by fitting the kinetic model onto measured conversions for various reaction conditions at 0.2, 0.5 and 0.8 solvent fractions. Thus obtained kpd0 and ktd0 kinetic parameters were extrapolated to zero solvent fractions and from obtained values of kinetic parameters the conversion points for bulk DAT polymerization were calculated and compared to measured conversion points.

Enhanced ionic polymerization of styrene induced by radiation

1963 ◽  
Vol 273 (1354) ◽  
pp. 387-399 ◽  
Keyword(s):  
Molecular Weight ◽  
Radiation Intensity ◽  
Chain Transfer ◽  
Average Molecular Weight ◽  
Surface Adsorption ◽  
Silica Powder ◽  
Intensity Dependence ◽  
Radiation Induced

The radiation-induced ionic polymerization of styrene at — 78 °C has been studied, at various concentrations in diehloromethane solutions, in the presence of silica powder, and at various radiation intensities. Both yield of polymer, and average molecular weight were determined, allowing an estimate of G i for ionic polymerization to be made. The yield is greatly reduced by traces of water and this is ascribed to increased termination. On the assumption that chain transfer is small, Aerosil powder appears to cause an increase in initiation, rather than a reduction in termination. Evidence is presented for the view that the enhanced reaction occurs by the surface adsorption of styrene ions, so that the radiation intensity dependence changes from I 1.0 to I 0.5 . Energy absorbed in the solvent is also found to be capable of initiation.

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