Catalytic Activity of New Oxovanadium(IV) Microclusters with 2-Phenylpyridine in Olefin Oligomerization

So far, few microclusters containing vanadium have been described in the literature. In this report, the synthesis protocol for the preparation of oxovanadium (IV) microclusters with 2-phenylpyridine is shown for the first time. Moreover, the crystal structure of these microclusters is also studied through the use of X-rays. The morphology of the prepared crystals is investigated using a field-emission Scanning Electron Microscope (SEM). The new compound, after activation by modified methylaluminoxane as the catalytic system, is investigated regarding the oligomerizations of 3-buten-1-ol, 2-chloro-2-propen-1-ol, allyl alcohol, and 2,3-dibromo-2-propen-1-ol. The products of oligomerization are tested by the TG-FTIR and MALDI-TOF-MS methods. Moreover, the values of catalytic activities for the new oxovanadium(IV) microclusters with 2-phenylpyridine are determined for the 3-buten-1-ol, 2-chloro-2-propen-1-ol, allyl alcohol, and 2,3-dibromo-2-propen-1-ol oligomerizations. Oxovanadium(IV) microclusters with 2-phenylpyridine are shown to be very highly active precatalysts for the oligomerization of allyl alcohol, 2,3-dibromo-2-propen-1-ol, and 3-buten-1-ol. However, in the case of 2-chloro-2-propen-1-ol oligomerization, the new microclusters are seen as highly active precatalysts.

Synthesis of 2-C-Branched Sugars

<p>A range of unnatural carbohydrates (sugars) with an unusual 2-C-bromomethylene branch have been synthesised by reaction of the 1,2-cyclopropanated carbohydrate 52 with different nucleophiles. Initial work to optimise the cyclopropane ring opening in the presence of sodium allyloxide/allyl alcohol provided anomers 140 and 141 in up to 75% yield. Use of sodium thiophenolate/thiophenol provided anomeric thioglycosides 181 and 182 (76% yield, 7:2 ratio), while sodium diethylamide/ diethylamine provided anomeric glycosylamines 183 and 184 (50% yield, 1:1 ratio). Further functionalisation of the 2-C-branch of 141 was performed using various palladium-catalysed cross-coupling reactions, providing a series of products. Reaction of 140 and 141 under acidic conditions caused E-Z isomerisation of the bromoalkene forming a single anomer, 194. Efforts to obtain mechanistic information about the cyclopropane ring opening were made through attempted trapping of a cyclopropene intermediate, deuterium labelling experiments, synthesis of possible stable intermediates and reactions with internal nucleophiles.</p>

Synthesis of 2-C-Branched Sugars

<p>A range of unnatural carbohydrates (sugars) with an unusual 2-C-bromomethylene branch have been synthesised by reaction of the 1,2-cyclopropanated carbohydrate 52 with different nucleophiles. Initial work to optimise the cyclopropane ring opening in the presence of sodium allyloxide/allyl alcohol provided anomers 140 and 141 in up to 75% yield. Use of sodium thiophenolate/thiophenol provided anomeric thioglycosides 181 and 182 (76% yield, 7:2 ratio), while sodium diethylamide/ diethylamine provided anomeric glycosylamines 183 and 184 (50% yield, 1:1 ratio). Further functionalisation of the 2-C-branch of 141 was performed using various palladium-catalysed cross-coupling reactions, providing a series of products. Reaction of 140 and 141 under acidic conditions caused E-Z isomerisation of the bromoalkene forming a single anomer, 194. Efforts to obtain mechanistic information about the cyclopropane ring opening were made through attempted trapping of a cyclopropene intermediate, deuterium labelling experiments, synthesis of possible stable intermediates and reactions with internal nucleophiles.</p>

The influence in difference of compatibilizers on the mechanical and rheological properties of LDPE/PLST blends

In this present study, low density polyethylene/plasticizer starch (LDPE/PLST) blends were prepared as a product to be used in disposable packaging (film applications), reducing the negative polymeric environmental effect. Because of their different molecular structures, LDPE blends with starch are fully immiscible; therefore, a compatibility agent is required. Three different polymer and/or copolymer: poly (vinyl alcohol) hydrolyzed 75% (PVOH), styrene-allyl alcohol copolymer (SAA) and polyethylene glycol (PEG) were selected as compatibilizers containing –OH groups. The effects of compatibilizer on the mechanical and rheological properties of LDPE/PLST blends were investigated and compared to LDPE/PLST without compatibilzer. The blends are also characterized by FTIR, which strongly indicates the existence of compatibilizers that can enhance phase interaction and promote compatibility in the blends of LDPE/PLST. Comparing to the blend without a compatibilizer, the tensile strengths of the blends containing PVOH and SAA increased significantly. The elongation at break results shows similar observation. The rheological measurement results suggested that the addition of a compatibilizer exhibited an increase in the shear stress and apparent viscosity comparing to the uncompatibilized blend except the blend with PEG which exhibited phase separation.

Experimental and Theoretical DFT Investigations in the [2,3]-Wittig-Type Rearrangement of Propargyl/Allyl-Oxy-Pyrazolones

Here we report the synthesis of interesting 3-alkyl-4-hydroxy-1-aryl-4-(propa-1,2-dienyl)1H-pyrazol-5(4H)-ones and 9-alkyl-7-aryl-1-oxa-7,8-diazaspiro[4.4]nona-3,8-dien-6-ones, starting from 1,2-diaza-1,3-dienes (DDs) and propargyl alcohol. The reaction proceeds through a sequence Michael-type nucleophilic attack/cyclization/[2,3]-Wittig rearrangement. In the same way, the reaction between the aforementioned DDs and allyl alcohol furnished 4-allyl-4-hydroxy-3-alkyl-1-aryl-1H-pyrazol-5(4H)-ones. A DFT study was also carried out, in order to have decisive clarifications about the mechanism.

Polymer Grafting of Graphene Oxide Through Esterification of Terephthalic Acid and Allyl Alcohol for Metronidazole Drug Delivery: Central Composite Design Optimization Study

The present study examined the direct esterification of terephthalic acid (TPA) with allyl alcohol (AA) on the graphene oxide (GO) surface in the presence of p-toluene sulfonic acid (PTSA) catalyst. Then, the surface of GO-TPAA was modified through polymerization reaction with 2,2’-azobisisobutyronitrile (AIBN) as a reaction initiator. The developed polymer was tested successfully as a nanocarrier for the metronidazole (MNZ) drug delivery. The resulting polymer was characterized by Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-Ray (EDX), Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The parameters were optimized by response surface methodology (RSM) based on the central composite design (CCD) experimental design. The maximum adsorption (93.31%) was obtained at pH = 5, contact time of 15 min, and MNZ concentration of 15 mg L− 1. Analysis of variance (ANOVA) study proposed that the obtained equation for the adsorption of the MNZ is quadratic and it is significant for the model. The drug release behavior indicated that the amount of MNZ release from nanocarrier was significantly pH dependent. The released data were fitted into different kinetic release model equations for determining the best-fit release model for the nanocarrier. The adsorption kinetic data best fitted the pseudo-second-order model with a coefficient of determination (R2) of 0.9999. The adsorption process was endothermic, following the Langmuir isotherm model (R2 = 0.9956). MNZ release was studied in vitro using stimulated gastric fluid and stimulated intestinal fluid. The proposed nanoadsorbent can be useful for the rapid and efficient adsorption of the drug.

Optimal modes of side-section flow in heat-pump-assisted extractive distillation systems for separating allyl alcohol–allyl acetate mixtures with butyl propionate

Objectives. To investigate the influence of side-section flow modes on the energy efficiency of a partially thermally coupled distillation sequence (PTCDS) with a vapor recompression heat pump for the extractive distillation of an allyl alcohol–allyl acetate mixture with n-butyl propionate and identify modes under which the combined use of a PTCDS and heat pump are the most efficient.Methods. Mathematical modeling in the Aspen Plus V10 software package was used as the main research method. The local composition equation of the non-random two-liquid model was used as a model for describing the vapor–liquid equilibrium, while the Redlich–Kwong model was used to consider the non-ideal vapor phase. When modeling the conventional extractive distillation scheme and PTCDS, parametric optimization was carried out according to the criterion of the total energy costs in the column reboilers. For the economical evaluation, Aspen Process Economic Analyzer V10.1 tools were used.Results. For extractive distillation of a mixture of allyl alcohol (30 wt %) and allyl acetate (70 wt %) with n-butyl propionate as an entrainer, the minimum energy consumption was achieved at the same side-section flow mode for the variants of a PTCDS with and without a heat pump. The reduction in energy costs relative to the conventional scheme was 20% for the sequence without a heat pump and 38% for that with a heat pump. An economic assessment was made of the best options in comparison with the conventional extractive distillation scheme. The PTCDS with a heat pump had an advantage over the sequence without a heat pump only for long periods of operation.Conclusions. For the extractive distillation of an allyl alcohol–allyl acetate mixture, the optimal modes for the combined use of a PTCDS with a vapor recompression heat pump coincide with the optimal modes for a PTCDS without a heat pump.