Epoxidation of karanja (Pongamia glabra) oil catalysed by acidic ion exchange resin

Karanja oil with an iodine value of 89 g/100 g was epoxidised in situ with aqueous hydrogen peroxide and acetic acid in the presence of Amberlite IR‐120 acidic ion exchange resin as catalyst. The effect of the operating variables on the oxirane oxygen content, as well as on the oxirane ring stability and the iodine value of the epoxidised karanja oil, were determined. The variables studied were stirring speed, hydrogen peroxide‐to‐ethylenic unsaturation molar ratio, acetic acid‐to‐ethylenic unsaturation molar ratio, temperature, and catalyst loading. The effects of these parameters on the conversion to the epoxidised oil were studied and the optimum conditions for the maximum oxirane content were established. The proposed kinetic model takes into consideration the two side reactions, namely, epoxy ring opening involving the formation of hydroxy acetate and hydroxyl groups, and the reaction between the peroxyacid and the epoxy group. The kinetic and adsorption constants of the rate equations were estimated by the best fit using Marquardt's algorithm. Good agreement between experimental and predicted data validates the proposed kinetic model. From the estimated kinetic constants, the apparent activation energy for the epoxidation reaction was found to be 11 kcal/mol.     

Kinetic Study on Oxirane Cleavage of Epoxidized Palm Oil

A ring-opened product (EPO-HOAc) was prepared using epoxidized palm oil (EPO) and acetic acid (HOAc). The kinetics of the oxirane cleavage of EPO were investigated at 50, 60, 70, 80, and 90 °C, respectively, in the presence of HOAc. The rate equation of oxirane cleavage was as follows: r = k[Ep][CH₃COOH]^1.6 ([Ep] is the molar concentration of oxiranes, [CH₃COOH] is the molar concentration of HOAc), and the activation energy of oxirane cleavage was 40.28 kJ mol⁻¹. The structure of EPO-HOAc was confirmed by FT-IR and ¹H NMR. The oxidative stability of EPO-HOAc was better than that of palm oil (PO), and the pour point of EPO-HOAc was lower than that of PO and EPO, which made EPO-HOAc more suitable for biodegradable lubricant materials than PO and EPO.     

Epoxidation of Canola Oil with Hydrogen Peroxide Catalyzed by Acidic Ion Exchange Resin

Canola oil with an iodine value of 112/100 g, and containing 60% oleic acid and 20% linoleic acid, was epoxidised using a peroxyacid generated in situ from hydrogen peroxide and a carboxylic acid (acetic or formic acid) in the presence of an acidic ion exchange resin (AIER), Amberlite IR 120H. Acetic acid was found to be a better oxygen carrier than formic acid, as it produced about 10% more conversion of ethylenic unsaturation to oxirane than that produced by formic acid under otherwise identical conditions. A detailed process developmental study was then performed with the acetic acid/AIER combination. The parameters optimised were temperature (65 °C), acetic acid to ethylenic unsaturation molar ratio (0.5), hydrogen peroxide to ethylenic unsaturation molar ratio (1.5), and AIER loading (22%). An iodine conversion of 88.4% and a relative conversion to oxirane of 90% were obtained at the optimum reaction conditions. The heterogeneous catalyst, AIER, was found to be reusable and exhibited a negligible loss in activity.     

Kinetic Studies on Oxirane Cleavage of Epoxidized Soybean Oil by Methanol and Characterization of Polyols

The kinetics of the oxirane cleavage of epoxidized soybean oil (ESO) by methanol (Me) without a catalyst was studied at 50, 60, 65, 70 °C. The rate of oxirane ring opening is given by k[Ep][Me]², where [Ep] and [Me] are the concentrations of oxiranes in ESO and methanol, respectively and k is a rate constant. From the temperature dependence of the kinetics thermodynamic parameters such as enthalpy (ΔH), entropy (ΔS), free energy of activation (ΔF) and activation energy (ΔE _a) were found to be 76.08 (±1.06) kJ mol⁻¹, −118.42 (±3.12) J mol⁻¹ k⁻¹, 111.39 (±2.86) kJ mol⁻¹, and 78.56 (±1.63) kJ mol⁻¹, respectively. The methoxylated polyols formed from the oxirane cleavage reaction , were liquid at room temperature and had three low temperature melting peaks. The results of chemical analysis via titration for residual oxiranes in the reaction system showed good agreement with IR spectroscopy especially the disappearance of epoxy groups at 825, 843 cm⁻¹ and the emergence of hydroxy groups at the OH characteristic absorption peak from 3,100 to 3,800 cm⁻¹.     

Synthesis,Characterization, and Properties of Multifunctional Epoxy Maleimide Resins

Summary: Novel multifunctional formaldehyde resins bearing diaminodiphenylmethane groups are synthesized by the polymerization of a mixture of diaminodiphenylmethane (DDM), o‐cresol (o‐Cz), and cyclohexanone (CH_x) with formaldehyde (FA) (at a molar ratio of monomers/formaldehyde, 1/1), in the presence of acid catalyst (HCl). The obtained resins are epoxidated with a large excess of epichlorohydrin and transformed into multifunctional epoxy resins. The multifunctional epoxy maleimide resins are obtained by reaction of the epoxy resins with carboxy phenyl maleimide in the presence of triethylamine as a catalyst. The resultant resins are characterized by IR and NMR spectroscopy, elemental, and thermal analysis. The curing and thermal behavior of these epoxy maleimide resin/DDM systems are investigated using differential scanning calorimetry (DSC) and thermogravimetry (TG) techniques. The activation energies of the curing reactions are situated in the range of 53–90 kJ · mol^?1. The cured products have good thermal properties, and activation energies of degradation reactions have values between 42–74 kJ · mol^?1.

The curing reaction of multifunctional epoxy maleimide resins with DDM.     

Thermochemistry of Evaporation and Sublimation of 2,4,6‐Triazido‐1,3,5‐triazine

Saturated vapor pressure over cyanuric triazide melt was measured in the temperature range 393.15–453.15 K using glass membrane Bourdon pressure gauges. Measured evaporation heat and evaporation entropy are equal to 61.1±3.3 kJ mol^–1 and 111.3±6.1 J mol^–1 K^–1, respectively. According to DSC data, melting heat and melting entropy of cyanuric triazide are 22.2±1.3 kJ mol^–1 and 60.5±3.5 J mol^–1 K^–1, respectively. Based on the results obtained, the following dependence was found for the saturated vapor pressure over solid cyanuric triazide: P _s [Pa]=10^14.0 ⋅ exp[(–83300±3300)/RT ]. Concequently, sublimation heat and sublimation entropy of cyanuric triazide are equal to 83.3±3.3 kJ mol^–1 and 171.8±9.6 J mol^–1 K^–1, respectively. Saturated vapor pressure over solid cyanuric triazide at room temperature is equal to 0.25 Pa (1.9×10⁻³ Torr). It is concluded that high volatility of cyanuric triazide is caused by its low sublimation heat.     

Synthesis and characterization of lactose based resorcinol resin

Resorcinol‐lactose resin was synthesized using phosphoric acid as the catalyst at 95°C. ¹³C‐NMR measurements proved that the chemical reaction is initiated at the 4‐ or 6‐carbon position in benzene ring. Sample separation by size‐exclusion chromatography (SEC) technology indicated that the resin consists of reacting mixtures of oligomer of lactose, glucose, and galacose with resorcinol. The resin, using a by product of diary industry as a main component, could be potentially applied as a novel adhesive to the wood process industry. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2581–2585, 2002     

The thermal degradation of poly(vinyl acetate) measured by thermal analysis-Fourier transform infrared spectroscopy

The elimination process which occurs during the thermal degradation of poly(vinyl acetate) has been studied using thermal analysis-Fourier transform infrared spectroscopy. It was found that elimination of acetate groups initially began slowly, but increased as degradation proceeded due to an additional process. The increase in rate was found to depend on the concentration of unsaturated groups in the polymer chain. The activation energy for the initial step was found to be 190 kJ mol⁻¹, while that for the additional process was 130 kJ mol⁻¹. The additional process of elimination was considered to be due to a four-membered transition state, activated by double bonds adjacent to the acetate unit.     

Synthesis and photocatalytic properties of iron(II)tetramethyl- tetra(1,4-dithiin)porphyrazine

The titled complex has been synthesized according to the template method from the prepared intermediate of 2,3-dicyano-5-methyl-1,4-dithiin in the presence of iron(II)sulfate heptahydrate and characterized by UV–vis, FT-IR , ¹H NMR, XPS and elemental analysis. The complex was supported on an Amberlite CG-400 resin to form a biomimetic catalyst, the ability of which for activating molecular oxygen was estimated from the degradation of Rhodamine B (RhB) under visible light irradiation in an aerated suspension. About 78% of the RhB was degraded in 27 h with a rate constant of 1.84 × 10⁻¹⁰ mol L⁻¹ s⁻¹. Aggregation between the dimer and monomer for the titled complex in DMSO or in DMF solution was observed from the concentration dependence in the UV–vis spectra. The effect of the aggregation was also demonstrated by the diffuse reflectance spectral measurement for the catalyst supported on the resin in saturated and supersaturated adsorption conditions. The monomer of catalyst has a higher capability to activate molecular oxygen for the degradation of organic pollutants than that of an aggregation form.     

Epoxidation of karanja (Pongamia glabra) oil by H2O2

Epoxidation of karanja oil (KO), a nondrying vegetable oil, was carried out with peroxyacetic acid that was generated in situ from aqueous hydrogen peroxide and glacial acetic acid. KO contained 61.65% oleic acid and 18.52% linoleic acid, respectively, and had an iodine value of 89 g/100 g. Unsaturated bonds in the oil were converted to oxirane by epoxidation. Almost complete epoxidation of ethylenic unsaturation was achieved. For example, the iodine value of the oil could be reduced from 89 to 19 by epoxidation at 30°C. The effects of temperature, hydrogen peroxide-to-ethylenic unsaturation ratio, acetic acid-to-ethylenic unsaturation ratio, and stirring speed on the epoxidation rate and on oxirane ring stability were studied. The rate constant and activation energy for epoxidation of KO were 10⁻⁶ L·mol⁻¹·s⁻¹ and 14.9 kcal·mol⁻¹, respectively. Enthalpy, entropy, and free energy of activation were 14.2 kcal·mol⁻¹, −51.2 cal·mol⁻¹·K⁻¹, and 31.1 kcal·mol⁻¹, respectively. The present study revealed that epoxides can be developed from locally available natural renewable resources such as KO.     

Kinetics of epoxidation of jatropha oil with peroxyacetic and peroxyformic acid catalysed by acidic ion exchange resin

The kinetics of epoxidation of jatropha oil by peroxyacetic/peroxyformic acid, formed in situ by the reaction of aqueous hydrogen peroxide and acetic/formic acid, in the presence of an acidic ion exchange resin as catalyst in or without toluene, was studied. The presence of an inert solvent in the reaction mixture appeared to stabilise the epoxidation product and minimise the side reaction such as the opening of the oxirane ring. The effect of several reaction parameters such as stirring speed, hydrogen peroxide-to-ethylenic unsaturation molar ratio, acetic/formic acid-to-ethylenic unsaturation molar ratio, temperature, and catalyst loading on the epoxidation rate as well as on the oxirane ring stability and iodine value of the epoxidised jatropha oil were examined. The multiphase process consists of a consecutive reaction, acidic ion exchange resin catalysed peroxyacid formation followed by epoxidation. The catalytic reaction of peroxyacetic/peroxyformic acid formation was found to be characterised by adsorption of only acetic (or formic) acid and peroxyacetic/peroxyformic acid on the active catalyst sites, and the irreversible surface reaction was the overall rate determining step. The proposed kinetic model takes into consideration two side reactions, namely, epoxy ring opening involving the formation of hydroxy acetate and hydroxyl groups and the reaction of the peroxyacid and epoxy group. The kinetic and adsorption constants of the rate equations were estimated by the best fit using nonlinear regression method. Good agreement between experimental and predicted data validated the proposed kinetic model. From the estimated kinetic constants, the apparent activation energy for epoxidation reaction was found to be 53.6 kJ/mol. This value compares well with those reported by other investigators for the same reaction over similar catalysts.     

Synthesis,thermal properties,and flame retardance of the epoxy‐silsesquioxane hybrid resins

Epoxy/silsesquioxane‐OH (EP‐SDOH, ED) hybrid resins were prepared from cyclohexyl‐disilanol silsesquioxane (SDOH) and diglycidyl ether of bisphenol A via the reaction between silanol and the oxirane group, with the cobalt naphthanate as a catalyst. It was found that incorporation of SDOH allows the reaction between oxirane ring and Si? OH, and the silsesquioxane cage structure can be the main chain or as the side chain of the hybrid resin. The EP‐SDOH hybrid resins with various SDOH contents were cured by 4,4′‐diaminodiphenylsulphone, and the curing reaction was investigated by differential scanning calorimetry. The curing characteristics of EP‐SDOH hybrids had been observed to be influenced by the content of SDOH in the hybrid. The differential scanning calorimetry thermograms indicated that the EP‐SDOH hybrid exhibited a higher initial temperature, peak temperature, as well as final temperature than those of the pure epoxy resin when cured by the same curing agent 4,4′‐diaminodiphenylsulphone. The curing kinetic parameters were calculated by using the Ozawa method and the results indicated that EP‐SDOH hybrids possess the same curing mechanism as the pure epoxy resin. The properties of the cured EP‐SDOH hybrid resins such as the glass transition temperature (T_g), dynamic mechanical analysis, thermal stability, as well as the flame retardance were also investigated, and the results showed that introducing silsesquioxane‐OH unit into epoxy resin successfully modified the local structure, made the chain stiffness, restrict the chain mobility, and eventually improved thermal stability and flame retardance of epoxy resin. POLYM. ENG. SCI., 47:225–234, 2007. © 2007 Society of Plastics Engineers.     

Synthesis,characterization and thermal degradation of poly[2‐(3‐p‐bromophenyl‐3‐methylcyclobutyl)‐2‐hydroxyethylmethacrylate]

In this work, 2‐(3‐p‐bromophenyl‐3‐methylcyclobutyl)‐2‐hydroxyethylmethacrylate (BPHEMA) [monomer] was synthesized by the addition of methacrylic acid to 1‐epoxyethyl‐3‐bromophenyl‐3‐methyl cyclobutane. The monomer and poly(BPHEMA) were characterized by FT‐IR and [¹H] and [¹³C]NMR. Average molecular weight, glass transition temperature, solubility parameter, and density of the polymer were also determined. Thermal degradation of poly[BPHEMA] was studied by thermogravimetry (TG), FT‐IR. Programmed heating was carried out at 10 °C min⁻¹ from room temperature to 500 °C. The partially degraded polymer was examined by FT‐IR spectroscopy. The degradation products were identified by using FT‐IR, [¹H] and [¹³C]NMR and GC‐MS techniques. Depolymerization is the main reaction in thermal degradation of the polymer up to about 300 °C. Percentage of the monomer in CRF (Cold Ring Fraction) was estimated at 33% in the peak area of the GC curve. Intramolecular cyclization and cyclic anhydride type structures were observed at temperatures above 300 °C. The liquid products of the degradation, formation of anhydride ring structures and mechanism of degradation are discussed. © 1999 Society of Chemical Industry     

Oxadiazoline and Ketoimine Palladium(II) Complexes as Highly Efficient Catalysts for Suzuki–Miyaura Cross‐Coupling Reactions in Supercritical Carbon Dioxide

The [2+3] cycloaddition of nitriles (RCN) with 2,2‐dimethyl‐3,4‐dihydro‐2H‐pyrrole 1‐oxide, in the presence of palladium dichloride (PdCl₂) gives the corresponding 2,3‐dihydro[1.2.4]oxadiazole (Δ⁴‐1,2,4‐oxadiazoline) palladium(II) complexes 1 – 4 in good yields. However, the Pd(II)‐assisted reaction of pentafluorobenzonitrile with the same pyrroline N‐oxide gives a mixture of oxadiazoline 5 , ketoimine 6 and pyrrolylbenzamide‐ketoimine 7 Pd(II) complexes, which affords upon heating in refluxing acetone the unprecedented fused tricyclic ketoimine complex 8 as the exclusive product. Under heating, compounds 5 and 7 transform to 6 , the latter undergoing intramolecular cyclization by nucleophilic attack of the amino moiety to the ortho carbon of the pentafluorophenyl ring leading ultimately to 8 . The compounds were characterized by IR, ¹H and ¹³C NMR, ESI⁺‐MS, elemental analyses and, in the cases of 3 , 6 , 7 and 8 , also by X‐ray diffraction analyses. The catalytic properties of the Pd complexes were evaluated in Suzuki–Miyaura cross‐coupling reactions, using supercritical carbon dioxide (scCO₂) as a green solvent. Cross‐couplings of aryl halides with phenylboronic acid give the desired biaryl products in quantitative yields, in a short reaction time, for substrate‐to‐catalyst molar ratios as high as 4.0⋅10⁴.     

Adsorption of cationic dye from aqueous solutions by activated carbon

Batch sorption experiments were carried out to remove a cationic dye, methylene blue (MB), from its aqueous solutions using a commercial activated carbon as an adsorbent. Operating variables studied were pH, stirring speed, initial methylene blue concentration and temperature. Adsorption process was attained to the equilibrium within 5 min. The adsorbed amount MB dye on activated carbon slightly changed with increasing pH, and temperature, indicating an endothermic process. The adsorption capacity of methylene blue did not significantly change with increasing stirring speed. The experimental data were analyzed by various isotherm models, and found that the isotherm data were reasonably well correlated by Langmuir isotherm. Adsorption measurements showed that the process was very fast and physical in nature. Thermodynamic parameters such as the adsorption entropy (ΔS^o) and adsorption enthalpy (ΔH^o) were also calculated as 0.165 kJ mol⁻¹ K⁻¹ and 49.195 kJ mol⁻¹, respectively. The ΔG^o values varied in range with the mean values showing a gradual increase from −0.256 to −0.780 to −2.764 and −7.914 kJ mol⁻¹ for 293, 313, 323 and 333 K, respectively, in accordance with the positive adsorption entropy value of the adsorption process.     

反相悬浮聚合法合成可生物降解海藻酸钠高吸水性树脂

以丙烯酸(AA)和海藻酸钠(SA)为原料,用反相悬浮聚合法合成了聚丙烯酸钠/海藻酸钠高吸水性树脂。研究了海藻酸钠、引发剂(KPS)和交联剂(NMBA)用量、丙烯酸中和度、聚合反应温度等因素对树脂吸水率的影响以及树脂的生物降解性能。结果表明,当w(SA)=1.5%、w(KPS)=0.15%、w(NMBA)=0.1%、丙烯酸中和度为65%、聚合反应温度为75℃时,树脂对蒸馏水的吸水率为845 g/g,对生理盐水的吸水率为88 g/g,且能被土壤和微生物降解,w(SA)=10%的树脂在60 d内能够被芽苞杆菌降解52%,在土壤中能被降解36%,且降解速度随海藻酸钠质量分数的增加而加快。IR测定表明,树脂为丙烯酸盐与海藻酸钠的接枝共聚物。SEM测定表明,PAA/SA高吸水性树脂呈花瓣结构。     

Hydroxyalkylation of barbituric acid. III. Product analysis and reaction pathway

Polyetherols containing a thermally stable pyrimidine ring were obtained upon the reaction of hydroxymethyl derivatives of barbituric acid with an excess of ethylene or propylene oxide. The reaction was monitored by ¹H‐NMR and IR spectroscopy for the systems with variable starting molar ratios of reagents. We found that formaldehyde rearranged from N‐hydroxymethyl and oxymethylene bridges into the end of the polyetherol chain during the reaction. Simultaneously, the O‐hydroxymethyl groups underwent blocking by oxirane. The structures of the polyetherols was deduced on the basis of the course of the reaction and the analytical data. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Preparation of poly(n-butyl acrylate) by ATRP using initiators for continuous activator regeneration (ICAR) in ionic liquid

The atom transfer radical polymerization (ATRP) of n-butyl acrylate (nBA) using initiators for continuous activator regeneration (ICAR) was successfully carried out in ionic liquid in the presence of a catalyst system of FeCl₃·6H₂O/succinic acid using 2-bromoisobutyrate as the initiator and 2,2′-azobisisobutyronitrile as the reducing agent. The ICAR ATRP of nBA was proved a ‘living’/controlled polymerization such as a linear increase of molecular weights of polymers with monomer conversion and relatively narrow polydispersities (<1.25) when the conversion was beyond 30% and its kinetics in this system was investigated. The polymerization rate increased with temperature and the apparent activation energy was calculated to be 32.84 kJ mol⁻¹. The chain extension experiment was carried out to confirm the controlled manner of the polymerization system. The resultant was characterized by nuclear magnetic resonance and gel permeation chromatography.     

Kinetic study on regeneration of FeEDTA in the wet process of NO removal

Cyclic voltammetry, quasi-steady-state polarization curves and potentiostatic step method were applied to study the regeneration of Fe^IIEDTA in the wet process of NO removal. The results showed that the Fe^IIIEDTA reduction was a fast reversible process with one electron transferred on Pt electrode surface. Standard rate constant k⁰ of Fe^IIIEDTA reduction at 298 K was found to be 0.0263 cm s⁻¹. According to the calculated diffusion activation energy of 24.93 kJ mol⁻¹, apparent activation energy of 25.74 kJ mol⁻¹ and the electron transfer activation energy of 16.56 kJ mol⁻¹, the rate-determining step for Fe^IIIEDTA reduction was diffusion step. Potentiostatic electrolysis tests revealed that direct electrochemical regeneration of Fe^IIEDTA in the wet process of NO removal was a promising method because of its high efficiency.     

Non-isothermal degradation kinetics of poly (2,2′-dihydroxybiphenyl)

Catalytic oxidative polymerization of 2,2′-dihydroxybiphenyl (DHBP) was performed by using Schiff base polymer-Cu (II) complex and hydrogen peroxide as catalyst and oxidant, respectively. According to size exclusion chromatography (SEC) analysis, the number-average molecular weight (M _n), weight-average molecular weight (M _w) and polydispersity index (PDI) values of poly (2,2′-dihydroxybiphenyl) (PDHBP) were found to be 37,500, 90,000 g mol⁻¹ and 2.4, respectively. The thermal degradation kinetics was investigated by thermogravimetric analysis in dynamic nitrogen atmosphere at four different heating rates: 5, 10, 15 and 20 °C min⁻¹. The derivative thermogravimetry curves of PDHBP showed that its thermal degradation process had one weight-loss step. The apparent activation energies of thermal decomposition for PDHBP as determined by Tang, Flynn–Wall–Ozawa (FWO), Kissenger–Akahira–Sunose (KAS), Coats–Redfern (CR) and Invariant kinetic parameter (IKP) methods were 109.1, 109.0, 110.0, 108.4 and 109.8 kJ mol⁻¹, respectively. The mechanism function and pre-exponential factor were determined by master plots and Criado–Malek–Ortega method. The most likely decomposition process was a D _n Deceleration type in terms of the CR, master plots and Criado–Malek–Ortega results.