Structure and Transesterification Reaction of Methyl 3-(Phenyldihalostannyl)propionates

The title compounds, PhX2SnCHECHECO2Me （X = C1, 1a; Br, 1b; I, 1c）, readily underwent transesterification into the corresponding analogues, PhX2SnCH2CH2CO2R when reacted with an alcohol ROH. The structural features of these compounds were described, and the possible mechanism of the novel transesterification was suggested.

N-Heterocyclic carbene-catalyzed synthesis of acetyltributylcitrate via a transesterification reaction

A new methodology for the synthesis of a green plasticizer acetyltributylcitrate through a transesterification reaction was developed. Under the catalysis of alkyl-substituted imidazol-type N-heterocyclic carbenes, tributyl citrate can react with vinyl acetate smoothly to give ATBC in high yield.

Tuning the cross-linked structure of basic poly(ionic liquid)to develop an efficient catalyst for the conversion of vinyl carbonate to dimethyl carbonate

Dimethyl carbonate(DMC)is a crucial chemical raw material widely used in organic synthesis,lithiumion battery electrolytes,and various other fields.The current primary industrial process employs a conventional sodium methoxide basic catalyst to produce DMC through the transesterification reaction between vinyl carbonate and methanol.However,the utilization of this catalyst presents several challenges during the process,including equipment corrosion,the generation of solid waste,susceptibility to deactivation,and complexities in separation and recovery.To address these limitations,a series of alkaline poly(ionic liquid)s,i.e.[DVBPIL][PHO],[DVCPIL][PHO],and[TBVPIL][PHO],with different crosslinking degrees and structures,were synthesized through the construction of cross-linked polymeric monomers and functionalization.These poly(ionic liquid)s exhibit cross-linked structures and controllable cationic and anionic characteristics.Research was conducted to investigate the effect of the cross-linking degree and structure on the catalytic performance of transesterification in synthesizing DMC.It was discovered that the appropriate cross-linking degree and structure of the[DVCPIL][PHO]catalyst resulted in a DMC yield of up to 80.6%.Furthermore,this catalyst material exhibited good stability,maintaining its catalytic activity after repeated use five times without significant changes.The results of this study demonstrate the potential for using alkaline poly(ionic liquid)s as a highly efficient and sustainable alternative to traditional catalysts for the transesterification synthesis of DMC.

Simulation for Transesterification of Methyl Acetate and n-Butanol in a Reactive and Extractive Distillation Column Using Ionic Liquids as Entrainer and Catalyst

A new reactive and extractive distillation process with ionic liquids as entrainer and catalyst （RED-IL）was proposed to produce methanol and n-butyl acetate by transesterification reaction of methyl acetate with n-butanol. The RED-IL process was simulated via a rigorous model, and high purity products of methanol and n-butyl acetate can be obtained in such a process. The effects of reflux ratio, feed mode, holdup, feed location, entrainer ratio and catalyst concentration on RED-IL process were investigated. The conversion of methyl acetate and purities of products increase with the holdup in column, entrainer ratio and catalyst content. An optimal reflux ratio exists in RED-IL process. Comparing to the mixed-feed mode, the segregated-feed mode is more effective, in which the optimal feed locations of reactants exist.

Transesterification of sunflower oil in microchannels with circular obstructions

The present paper studied numerical and experimentally the transesterification reaction between sunflower oil and ethanol with NaO H catalyst in microchannels with circular obstructions. The micromixer design influence on fluid mixing and oil conversion was investigated for a range of operating conditions: Reynolds number(Re = 0.1–100),Temperature(25–75 °C), ethanol/oil molar ratio(6-12), and catalyst concentration(0.75 wt%–1.25 wt%), using three microchannel configurations(Length = 35 mm; Width = 1500 μm; Height = 200 μm): T-shape – channel without obstructions; MCO – channel with 3 obstructions ensemble – equally disposed over longitudinal length;MWO – channel with 7 obstructions ensemble. The MCO micromixer was based on literature work, and the MWO is a totally new micromixer design. Experimental tests were conducted in similar conditions in microreactors using these micromixers(Length = 411 mm) made of polydimethylsiloxane. The MCO configuration presented the highest performance(mixing index of 0.80 at Re = 100), oil conversion of 81.13% at 75 °C, molar ratio of 9 and catalyst concentration of 1%. Experimental results showed high conversions for MCO and MWO configurations(99.99%) at 50 °C, molar ratio of 9 and catalyst concentration of 1%, with a residence time of 12 s.

Reaction Kinetics of Biodiesel Synthesis from Waste Oil Using a Carbon-based Solid Acid Catalyst

The kinetics of simultaneous transesterification and esterification with a carbon-based solid acid catalyst was studied.Two solid acid catalysts were prepared by the sulfonation of carbonized vegetable oil asphalt and petroleum asphalt.These catalysts were characterized on the basis of elemental analysis,acidity site concentration,the Brunauer-Emmett-Teller（BET）surface area and pore size.The kinetic parameters with the two catalysts were determined,and the reaction system can be described as a pseudo homogeneous catalyzed reaction.All the forward and reverse reactions follow second order kinetics.The calculated concentration values from the kinetic equations are in good agreement with experimental values.

Efficient synthesis of 1,6-hexamethylene diurethane through coupling transesterification and methoxycarbonylation with methyl phenyl carbonate as intermediate

A reaction coupling system of transesterification and methoxycarbonylation with methyl phenyl carbonate （MPC） as intermediate was established to efficiently prepare 1,6-hexamethylene diurethane （HDU） from 1,6- bexametbylene diamine （HDA）. The feasibility of the system was explored using the thermodynamics analysis, the reaction mechanism and the experiment results. The optimal reaction was carried out to get higher HDU yield. The thermodynamic analysis showed that the metboxycarbonylation of HDA with MPC, the Gibbs free energy of which was negative, was a spontaneous process. Furthermore, the equilibrium constant of the methoxycarbonylation of HDA with MPC was much greater than that of the transesterification of dimethyl carbonate （DMC） with phenol, so the reaction coupling could be realized under mild conditions. The reaction mechanism analysis indicated that phenoxy anion was the key spedes for reaction coupling. Higher MPC concentration was detected when sodium phenoxide was used as transesterification reactant with DMC, since the phenoxy anion of sodium phenoxide could be dissociated more easily. Sodium pbenoxide was more suitable to prepare HHDU through reaction coupling. A yield of HDU as high as 98.3% could be reached under the optimal conditions of mPhONa/mDMC = 0.027 and nDMC/nHDa = 8/1 at 90 ℃ in 2 h.

Biodiesel Production from Waste Cooking Oil by Enzymatic Catalysis Process

Biodiesel is an excellent option for reducing dependence on fossil fuels with environmental advantages by reducing hazardous emissions. The enzymatic transesterification has attracted the attention of researchers in the last decade and the advantages of enzymatic catalysis show that the production of biodiesel by this route has good potential, mainly because it is friendly environment. For biodiesel, production process by enzyme catalysis is chosen the response surface methodology. It is an experimental strategy to find the best operating conditions oftransesterification reaction to improve the biodiesel quality. The Process has three variables： temperature, molar ratio oil-alcohol and catalyst quantity. The process was monitored by GC-FID （gas chromatography with flame ionization detector）. The yield of the transesterification reaction by enzymatic catalysis decreases with increasing temperature, and may be due to inactivation of the enzyme by denaturation at temperatures above 50 ℃. The second-order design used was the ＂CDC （central design composition）＂ which produced a maximum yield of 95.5% in the transesterification reaction by enzymatic catalysis obtained at a temperature of 45 ℃, molar ratio methanol：oil of 8：1 and a catalyst loading of 8% wt.

Evaluation of Performance and Emission Characteristics of Biodiesel Fuel Produced from Rapeseed Oil

The objective of the present study is to examine and compare the performance and emission characteristic of two biodiesel fuels produced from rapeseed oil via transesterification method.Tested biodiesel fuels(ROME(Rapeseed Oil Methyl Ester)and ROEE(Rapeseed Oil Ethyl Ester))were selected based on their properties obtained from an optimization of transesterification conditions.A Yanmar diesel engine has led to evaluating their performance parameters such as fuel consumption rate,exhaust gas temperature and emission characteristic corresponding to nitrogen oxides(NOx),carbone monoxide(CO)and carbon dioxide(CO2).A comparative analysis was carried out using normal diesel fuel tested in same experimental conditions.Fuel consumption rate was measured by observing the volumetric rate from the fuel tank of the engine supported by stopwatch.The exhaust gas temperature and emission characteristic were measured simultaneously by using a testo 350 flue gas analyzer.According to the results,biodiesel fuels showed a higher fuel consumption rate and exhaust gas temperature under an increase of engine speed.They also exhibited lower NOx emission with a slight rise in CO and CO2 emission compared to mineral diesel fuel.ROME exhibited low emission gas compared to ROEE and mineral diesel.It can be evaluated as a promising alternative fuel for diesel engine.

A Study on the Impact of Chemical Structure on the Evolution of Aggregate Structure in Fiber-shaped High Density Polyethylene Vitrimer

Vitrimers have emerged as a prominent research area in the field of polymer materials.Most of the studies have focused on synthesizing polymers with versatile dynamic crosslinking structures,while the impact of chemical structure on aggregate structure of vitrimers,particularly during polymer processing,remains insufficiently investigated.The present study employed commercial maleic anhydride-grafted-high density polyethylene(M-g-HDPE)as the matrix and hexanediol as the crosslinker to facilely obtain fiber-shaped HDPE vitrimers through a reaction extrusion and post-drawing process.Through chemical structure characterization,morphology observation,thermal and mechanical properties investigation,as well as aggregate structure analysis,this work revealed the influence of dynamic bonds on the formation of aggregate structures during fiber-shaped vitrimers processing.A small amount of dynamic bonds in HDPE restricts the motion of PE chain during melt-extruding and post-drawing,resulting in a lower orientation of the PE chains.However,lamellar growth and fibril formation during post-drawing at high temperature are enhanced to some extent due to the competition between dynamic bond and chain relaxation.The uneven morphology of fibershaped HDPE vitrimers can be attributed to the stronger elastic effect brought by dynamic bonding,which plays a more dominant role in determining the mechanical properties of fiber-shaped vitrimers compared to aggregate structure.Abstract Vitrimers have emerged as a prominent research area in the field of polymer materials.Most of the studies have focused on synthesizing polymers with versatile dynamic crosslinking structures,while the impact of chemical structure on aggregate structure of vitrimers,particularly during polymer processing,remains insufficiently investigated.The present study employed commercial maleic anhydride-grafted-high density polyethylene(M-g-HDPE)as the matrix and hexanediol as the crosslinker to facilely obtain fiber-shaped HDPE vitrimers through a reaction extrusion and post-drawing process.Through chemical structure characterization,morphology observation,thermal and mechanical properties investigation,as well as aggregate structure analysis,this work revealed the influence of dynamic bonds on the formation of aggregate structures during fiber-shaped vitrimers processing.A small amount of dynamic bonds in HDPE restricts the motion of PE chain during melt-extruding and post-drawing,resulting in a lower orientation of the PE chains.However,lamellar growth and fibril formation during post-drawing at high temperature are enhanced to some extent due to the competition between dynamic bond and chain relaxation.The uneven morphology of fibershaped HDPE vitrimers can be attributed to the stronger elastic effect brought by dynamic bonding,which plays a more dominant role in determining the mechanical properties of fiber-shaped vitrimers compared to aggregate structure.

Kinetic Resolution of 2-Chloro-1-（3,4-dichlorophenyl）ethanol by Lipase-Catalyzed Transesterification

Kinetic resolution of racemic 2-chloro-1-（3,4-dichlorophenyl）ethanol was performed by free Alcaligene sp. lipase-catalyzed irreversible transesterification affording the （R）-isomer with ≥95% ee and the （S）-isomer with ≥90% ee. The activity of lipase Alcaligene sp. strongly depends on the basicity of the reaction system, and an organic base such as triethylamine can enhance the activity of the lipase and enantioselectivity markedly.

Magnesium single-atom catalysts with superbasicity

Magnesium-related solid bases have long been considered catalysts with weak or medium basicity.Here we report the fabrication of Mg single-atom catalysts with superbasicity for the first time.A sublimation-migration-anchoring strategy is employed,in which the Mg net is sublimated,transported by Ar,and trapped by defective graphene(producing Mg_(1)/G).Simulated and experimental results demonstrate that Mg single atoms are anchored on graphene in tetra-coordination,and Mg single atoms cooperating with C atoms give superbasicity,which differs from conventional alkali/alkaline earth metal oxides with basicity originating from O atoms.This new solid base is highly active in the synthesis of dimethyl carbonate through transesterification of ethylene carbonate with methanol,which is usually catalyzed by strong bases.The turnover frequency value reaches 99.6 h^(-1) on Mg_(1)/G,which is much higher than that of traditional Mg-related counterparts(1.0–5.6 h^(-1))and even superior to that of typical Na and K-related solid superbases(29.8–36.2 h^(-1))under similar conditions.

Rosin side chain type catalyst-free vitrimers with high cross-link density,mechanical strength,and thermal stability

The emergence of vitrimer,a new class of polymer materials can address the problem of recyclability,reprocess ability and recyclability of thermosetting plastics.Rosin,a natural product,is an ideal raw material for the preparation of polymers in a more sustainable way.Nevertheless,due to the huge steric hindrance caused by the hydrogenated phenanthrene ring structure,the cross-link density of materials is frequently lowered.In this study,hydrogenated rosin was adopted for preparing hydrogenated rosin side-chain type diacids,which were reacted with mixed epoxy to obtain rosin side-chain type vitrimers.It was completely characterized by differential scanning calorimetry test,thermogravimetric analysis,shape memory test and self-healing test.The prepared vitrimers exhibited good self-healing properties,excellent heat resistance(T_(d)=352℃)as well as high mechanical properties(tensile strength of 46.75 MPa).The tricyclic diterpene structure of rosin was introduced into the side chain in order to avoid the reduction of cross-link density resulting from the huge steric hindrance of the rigid tricyclic hydrophenylene skeleton.Vitrimers can undergo dynamic transesterification reaction without external catalysts due to the autocatalytic effect of tertiary amines from epoxy.Moreover,our work expanded the application field of rosin,increased the added value of rosin,and provided a novel method for preparing rosin-based vitrimers with ideal properties.

Rational fabrication of ordered porous solid strong bases by utilizing the inherent reducibility of metal-organic frameworks

Ordered porous solid strong bases(OPSSBs)have attracted great research interest due to the excellent performance as heterogeneous catalysts in various reactions.The main obstacle for fabricating OPSSBs is the requirement of high temperature to produce strong basicity on ordered porous materials.For example,the temperatures of 600-650℃ are required for the decomposition of base precursor NaNO_(3)to basic sites on mesoporous silica SBA-15 and zeolite Y.Such high decomposition temperatures are energy-intensive and harmful to the structure of supports.Herein,we report the fabrication of OPSSBs by utilizing the redox interaction between base precursor and low-valence metal centers(e.g.,Cr^(3+))in metal-organic frameworks(MOFs).The base precursor NaNO_(3)on MIL-101(Cr)can be converted to basic sites entirely at 300℃,which is quite lower than those of the conventional thermal conversion on SBA-15 and zeolite Y(600-650℃).The exploration on decomposition mechanism reveals that the valence change of Cr^(3+)to Cr^(6+)takes place during the conversion of NaNO_(3)to basic sites.In this way,MOFs-derived base catalysts have been synthesized successfully by the host-guest redox strategy and exhibit high catalytic activity in typical base-catalyzed reactions.

Photodirected 2D-to-3D morphing structures of shape memory polycaprolactone/W_(18)O_(49) nanowires composite film

Shape memory materials possess programmable complex and large deformations towards external stimuli,which are particularly essential for their potential applications.For the transformation of planar two-dimensional(2D)structures into complex 3D structures,the design of asymmetric or bilayer thin sheets is usually required.In this paper,we propose a facile strategy to achieve these complex 3D structures that can be transformed to various pre-determined shapes sequentially by laser-triggered site-specific deformations.The response of shape memory polycaprolactone(PCL)to laser is realized by physically dopingW18O49 nanowires into the cross-linked PCL diacrylate matrix.When irradiated by 98 mW cm^(−2)laser,the pre-stretched PCL/W_(18)O_(49)film shows an out-of-plane bending deformation due to the temperature gradient and single-domain orientation on the thickness between the upper layer and lower layer.The bending rates and amplitudes of the film can be tailored by adjusting the parameters of irradiation time,the film thickness as well as the pre-stretch strain.Remarkably,the pre-stretched film can automatically bend in more intricate complex deformations by integration with kirigami cuts in planar.Finally,we demonstrate that by activating the dynamic transesterification reaction within the same film,it can also achieve the 2D-to-3D transformations.With these decent features,this kind of novel PCL//W_(18)O_(49)film shows great potential in the field of biomedical devices or soft robotics.

Development of solid base catalyst X/Y/MgO/-Al_(2)O_(3) for optimization of preparation of biodiesel from Jatropha curcas L.seed oil

The preparation and regeneration conditions of the identified catalyst X/Y/MgO/?-Al2O3 with high catalytic activity were studied and optimized. The biodiesel was prepared by transesterification of Jatropha curcas seed oil produced in Guizhou with methanol at its reflux temoerature in the presence of X/Y/MgO/?-Al2O3 . The pilot plant tests were carried out in a 100 L reaction vessel. Both average yield and fatty acid methyl esters (FAME) content reached more than 96.50% under the optimum reaction conditions of the pilot plant tests designed with an oil/methanol molar ratio of 1 : 10, catalyst concentration of 1.00%, and reaction time of 3 h at reflux temperature. In addition, analysis shows that the quality of biodiesel meets the standard EN 14214.