Mathematical modelling of oleic acid epoxidation via a chemo-enzymatic route-From reaction mechanisms to reactor model

The immobilized enzyme lipase acts as an efficient, selective and durable catalyst in the direct transformation of unsaturated carboxylic acids to epoxides, which are used as chemical intermediates and biolubricants. Experimental data obtained from the epoxidation of a model molecule, oleic acid in a laboratory-scale isothermal batch reactor were critically evaluated and mathematically modelled in the most precise way. Several rival surface reaction mechanisms were proposed and rate equations based on these mechanisms were derived. The rate equations were implemented in a multiphase model for the laboratory-scale batch reactor and the kinetic and adsorption parameters included in the rate equations were estimated with non-linear regression analysis. Based on the parameter estimation statistics and chemical knowledge, the most plausible kinetic models for the chemo-enzymatic epoxidation of oleic acid on the immobilized lipase catalyst were selected. The best kinetic models gave a good reproduction of the experimental data. The models can be used to predict the performance of enzymatic epoxidation of unsaturated fatty acids. (c) 2021 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)

Epoxidation of vegetable oils : process intensification for biomass conversion

Oils extracted from plants, algae, seeds and wood are one of the vast biomass resources which can be used to elaborate a wide range of products. Tall oil obtained from forest biomass is a good source of vegetable oils, because it is a non-edible by-product of Kraft pulping process and it represents an abundant feedstock, particularly in Nordic countries. Epoxidized vegetable oils and fatty acids are used for developing PVC-derived plastic-ware and as intermediates for the synthesis of biolubricants, polyols, glycols, olefinic compounds and stabilizers for polymers. In other words, epoxidized vegetable oils are green platforms by excellence for the development of products and present an alternative to its derivation from non-renewable fossil resources. This work has focused on the study of the Prilezhaev epoxidation of plant oils as a green process, since it uses renewable raw materials and produces biodegradable products through a non-toxic synthesis route. An important aspect of this thesis was the application of process intensification in the form of microwave irradiation, heterogeneous catalysis and new mixing technology (a rotating bed reactor) for a more energy-efficient process with higher product yields, compared to more conventional approaches. The reaction was executed by peracetic acid formed in situ from acetic acid and hydrogen peroxide. Epoxidation of oleic acid as a model compound and tall oil mixtures was performed in a batch loop reactor. The core of the reactor system was a vigorously stirred tank which was coupled to a loop with a microwave cavity and a heat exchanger. The microwave effect was compared with the results obtained with conventional heating. The reactor system was equipped with a special mixing device (SpinchemTM), which allowed to immobilize solid resin catalysts and to minimize mass transfer limitations of the oilaqueous-solid system. An extensive series of kinetic experiments was carried out in the presence and absence of microwave irradiation and heterogeneous catalysts. Typical reaction temperatures were 40-70°C. From the separated aqueous and organic phases, the concentrations of acetic acid, hydrogen peroxide, peracetic acid as well as double bonds in the reactant oil and epoxidized oil were determined by titrimetric analysis. The kinetics of ring opening reactions was studied separately and some of the ring opening products were identified by NMR analysis. The results showed that an increased temperature, as well as higher concentrations of acetic acid and hydrogen peroxide accelerated both the epoxidation and the ring opening processes. The epoxidation of oleic acid occurs spontaneously in the absence of the catalyst, but the reaction yield can be considerably improved by exposing the system to microwave irradiation and incorporating a solid catalyst. Several heterogeneous catalysts were screened to find the highest performance. However, the microwave effect was not visible in the presence of heterogeneous catalysts and microwave irradiation showed to be detrimental for the yields of tall oil epoxidation. Detailed mathematical modelling of the multiphase system was carried out, starting from first principles. Detailed kinetic models based on reaction mechanisms were derived and the model parameters were estimated by non-linear regression analysis. The models for epoxidation with conventional heating and microwave irradiation in the presence and absence of a solid catalyst had a good correspondence between the experimental and calculated concentrations of the reaction components. The rate constants and activation energies for the perhydrolysis, epoxidation and ring opening reactions were obtained as a result of the parameter estimation

Epoxidation of oleic acid under conventional heating and microwave radiation

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DETERMINATION OF 3-HYDROXY-3-PYRROLINE-2-ONE IN URINE AND STUDY OF ITS EXCRETION FROM THE ORGANISM OF LABORATORY ANIMALS

It is known that almost any disease of the central nervous system is accompanied by the development of cognitive disorders. The drugs of choice in the complex therapy in this case are nootropics. On the world market racetam group, i.e. derivatives of alpha-pyrrolidone, prevails among nootropics, and the derivatives have a wide spectrum of pharmacological activity. Currently, this group continues to expand. By the employees of Perm State Pharmaceutical Academy (PSPA), ruled by Professor V.L. Gein, a new biologically active compound, a 3-pyrrolin-2-one derivative KOH-1 was synthesized. This compound is at the preclinical research stage now.The aim of this work was the development of methods for determination of KOH-1 in urine by high performance liquid chromatography (HPLC), the study of excretion KOH-1 from the organism of laboratory animals.Materials and methods. Studies on the development of methods were carried out by using a liquid chromatograph LC-20 Prominence (Shimadzu, Japan) with a diode-array detector. The validation was carried out in accordance with the requirements for bioanalytical methods, in terms of selectivity, linearity, precision and accuracy. The study of excretion of KOH-1 was performed on white non-linear male rats weighing 300-400 g. The substance KOH-1 was administered once orally in a suspension of starch mucus at a dose of 100 mg/kg.Results and discussion. As a result of the research, the  method for determining the biologically active compound KOH-1 in urine has been developed. The validation showed its suitability for pharmacokinetic studies. The data on daily excretion of KOH-1 in urine after a single oral administration to rats were obtained.Conclusion. The developed conditions for the chromatographic determination of KOH-1 in urine can be used in pharmacokinetic studies, both at the preclinical and clinical stages of the study of a potential drug. The data on excretion of KOH-1 will allow to determine the ways of excretion of the preparation, and also to select a rational dosage, to identify possible contraindications to the use

The Lord of the Chemical Rings: Catalytic Synthesis of Important Industrial Epoxide Compounds

International audienceThe epoxidized group, also known as the oxirane group, can be considered as one of the most crucial rings in chemistry. Due to the high ring strain and the polarization of the C–O bond in this three-membered ring, several reactions can be carried out. One can see such a functional group as a crucial intermediate in fuels, polymers, materials, fine chemistry, etc. Literature covering the topic of epoxidation, including the catalytic aspect, is vast. No review articles have been written on the catalytic synthesis of short size, intermediate and macro-molecules to the best of our knowledge. To fill this gap, this manuscript reviews the main catalytic findings for the production of ethylene and propylene oxides, epichlorohydrin and epoxidized vegetable oil. We have selected these three epoxidized molecules because they are the most studied and produced. The following catalytic systems will be considered: homogeneous, heterogeneous and enzymatic catalysis

Kinetic modelling of Prileschajew epoxidation of oleic acid under conventional heating and microwave irradiation

International audienceEpoxidation of oleic acid by peracetic acid (PAA) was studied in a recycled reactor system under conventional heating and microwave irradiation. This reaction system consists of several steps. Thus, a kinetic modelling strategy to diminish the number of parameters to be estimated was developed by investigating each reaction step: PAA synthesis and decomposition, epoxidation and ring-opening. The energy balance for microwave heating was correlated with the concentration of the microwave-absorbent species and the total input power of the microwaves. The epoxidation reaction was conducted in the vigorously stirred tank reactor under isothermal conditions within a temperature range of 50–70 °C. The organic phase content was 32–45% v/v. The interfacial mass transfer was supposed to be faster than the intrinsic reaction kinetics suppressing the use of mass transfer correlations. Nonlinear regression was used to estimate the kinetic parameters. Two models were developed for microwave and conventional heating respectively. The perhydrolysis showed to be the slowest reaction, followed by the epoxidation and the ring-opening. The use of microwave irradiation resulted in considerable process intensification for the epoxidation process. By employing microwave heating, the perhydrolysis step in the aqueous phase was enhanced, and the reaction time was reduced by 50% in best cases, which implies that the reactor size can be diminished by microwave technology

Screening of ion exchange resin catalysts for epoxidation of oleic acid under the influence of conventional and microwave heating

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Influence of ring-opening reactions on the kinetics of cottonseed oil epoxidation

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Epoxidation of Tall Oil Catalyzed by an Ion Exchange Resin under Conventional Heating and Microwave Irradiation

International audienceTall oil fatty acids (TOFA) are a byproduct from the Kraft pulping process, and they represent a renewable and inexpensive alternative with high potential as a renewable feedstock. Epoxidized TOFA have great potential as chemical intermediates. Epoxidation of oleic acid, TOFA, and distilled tall oil (DTO) was conducted in an isothermal batch reactor with in situ-formed peracetic acid using hydrogen peroxide as the reactant and acetic acid as the reaction carrier. Amberlite IR-120 was used as the solid heterogeneous catalyst. The catalyst loading effect, the reactant ratios, the reaction temperature (40–70 °C), and the influence of microwave irradiation on epoxidation and ring opening were studied. The application of microwave irradiation resulted in an improvement of the epoxidation rate in the absence of the catalyst. Lower product yields were obtained for the epoxidation of DTO than for TOFA because of the higher viscosity and high content of rosin acids which presumably promoted ring opening reactions. At higher temperatures, the selectivity to oxirane decayed due to ring opening. Titration analysis and NMR analysis confirmed that microwave irradiation induces the ring opening reactions for TOFA epoxidation, and it accelerates this process for DTO. The rapid nature of the microwave heating might have unchained a series of ring opening reactions between neighboring oxirane groups and with the nucleophilic agents in the reaction mixture

Epoxidation of Fatty Acids and Vegetable Oils Assisted by Microwaves Catalyzed by a Cation Exchange Resin

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