Kinetic analysis of the partial synthesis of artemisinin: Photooxygenation to the intermediate hydroperoxide

AbstractThe price of the currently best available antimalarial treatment is driven in large part by the limited availability of its base drug compound artemisinin. One approach to reduce the artemisinin cost is to efficiently integrate the partial synthesis of artemisinin starting from its biological precursor dihydroartemisinic acid (DHAA) into the production process. The optimal design of such an integrated process is a complex task that is easier to solve through simulations studies and process modelling. In this article, we present a quantitative kinetic model for the photooxygenation of DHAA to an hydroperoxide, the essential initial step of the partial synthesis to artemisinin. The photooxygenation reactions were studied in a two-phase photo-flow reactor utilizing Taylor flow for enhanced mixing and fast gas-liquid mass transfer. A good agreement of the model and the experimental data was achieved for all combinations of photosensitizer concentration, photon flux, fluid velocity and both liquid and gas phase compositions. Deviations between simulated predictions and measurements for the amount of hydroperoxide formed are 7.1 % on average. Consequently, the identified and parameterized kinetic model is exploited to investigate different behaviors of the reactor under study. In a final step, the kinetic model is utilized to suggest attractive operating windows for future applications of the photooxygenation of DHAA exploiting reaction rates that are not affected by mass transfer limitations.

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A Qualitative Numerical Study on Catalytic Hydrogenation of Nitrobenzene in Gas-Liquid Taylor Flow with Detailed Reaction Mechanism

Fluids ◽

10.3390/fluids5040234 ◽

2020 ◽

Vol 5 (4) ◽

pp. 234

Author(s):

Mino Woo ◽

Lubow Maier ◽

Steffen Tischer ◽

Olaf Deutschmann ◽

Martin Wörner

Keyword(s):

Mass Transfer ◽

Reaction Mechanism ◽

Catalytic Hydrogenation ◽

Density Functional ◽

Numerical Study ◽

Initial Period ◽

Reaction Rates ◽

Surface Species ◽

Two Phase ◽

Taylor Flow

While the number of computational studies considering two-phase flows in microfluidic systems with or without mass transfer is increasing, numerical studies incorporating chemical reactions are still rare. This study aims to simulate the catalytic hydrogenation of nitrobenzene in gas-liquid Taylor flow by combining interface-resolving numerical simulations of two-phase flow and mass transfer by a volume-of-fluid method with detailed modeling of the heterogeneous chemical reaction by software package DETCHEMTM. Practically relevant physical properties are utilized for hydrodynamic and mass transfer simulations in combination with a preliminary reaction mechanism based on density functional theory. Simulations of mass transfer are conducted using a predetermined velocity field and Taylor bubble shape. At the beginning of the simulation when liquid nitrobenzene is not saturated by hydrogen, axial profiles of surface species concentrations and reaction rates show local variations. As hydrogen dissolves in nitrobenzene, the concentration profiles of surface species at the wall become uniform, eventually reaching an equilibrium state. Neglecting the local variation in a short initial period will allow further simplification of modeling surface reactions within a Taylor flow.

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Numerical Investigation of Biodiesel Production in Capillary Microreactor

Volume 2: 31st Computers and Information in Engineering Conference, Parts A and B ◽

10.1115/detc2011-48765 ◽

2011 ◽

Author(s):

Wei Han ◽

Rachaneewan Charoenwat ◽

Brian H. Dennis

Keyword(s):

Mass Transfer ◽

Volume Flow Rate ◽

Flow Behavior ◽

Chemical Species ◽

Reaction Rates ◽

Immiscible Fluids ◽

Biodiesel Production ◽

Reacting Flow ◽

Two Phase ◽

Capillary Microreactor

Synthesis of biodiesel through transesterification of vegetable oil with methanol has been experimentally studied in different types of microreactors though detailed numerical simulation has not yet been presented. The capillary microreactor has the potential to greatly intensify mass transfer between immiscible fluids that would result in higher chemical reaction rates. A segmented flow pattern of oil and methanol forms within the reactor. It has been shown experimentally that the two phase flow has dramatic benefits on the intensification of mass transfer and heat transfer. Such reactors have been proposed for the synthesis of biodiesel and detailed understanding of flow dynamics and chemical kinetics would be useful for process optimization. This paper presents a mathematical model and numerical solution for the synthesis of biodiesel in a capillary reactor. The model represents the unsteady incompressible viscous non-equilibrium chemically reacting flow. The equations are discretized with the finite element method (FEM) and solved to demonstrate the flow behavior and concentration distribution of each chemical species within two phases; different residence time will be obtained with different volume flow rate as well. Information about efficient computational treatment of the model will also be presented.

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Mass transfer in heterogeneous system enzyme-substrate; Kinetic model of enzymatic reaction in system of two immiscible liquids

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19823019 ◽

1982 ◽

Vol 47 (11) ◽

pp. 3019-3026 ◽

Cited By ~ 2

Author(s):

František Kaštánek ◽

Jindřich Zahradník ◽

Germanico Ocampo

Keyword(s):

Mathematical Model ◽

Mass Transfer ◽

Kinetic Model ◽

Interphase Boundary ◽

Heterogeneous System ◽

Enzymatic Reaction ◽

Reaction Rates ◽

Immiscible Liquids ◽

Enzyme Substrate

Mathematical model is proposed enabling calculation of enzymatic reaction rates occuring in one phase of a system of two immiscible liquids under conditions of substrate and product transfer over the interphase boundary.

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Rate Constant Change of Photo Reaction of Bacteriorhodopsin Observed in Trimeric Molecular System

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2016.12318 ◽

2016 ◽

Vol 16 (4) ◽

pp. 3431-3435 ◽

Cited By ~ 2

Author(s):

Yutaka Tsujiuchi ◽

Hiroshi Masumoto ◽

Takashi Goto

Keyword(s):

Kinetic Model ◽

Differential Equations ◽

Molecular Interaction ◽

Reaction Rate ◽

Molecular System ◽

Red Light ◽

Initial Step ◽

Reaction Rates ◽

Constant Change ◽

Linear Differential

To elucidate the time evolution of photo reaction of bacteriorhodopsin in glycerol mixed purple membrane at around 196 K under irradiation by red light, a kinetic model was constructed. The change of absorption with irradiation at times of 560 nm and 412 nm was analyzed for the purpose of determining reaction rates of photo reaction of bacteriorhodopsin and its product M intermediate. In this study it is shown that reaction rates of conversion from bacteriorhodopsin to the M intermediate can be explained by a set of linear differential equations. This model analysis concludes that bacteriorhodopsin in which constitutes a trimer unit with other two bacteriorhodopsin molecules changes into M intermediates in the 1.73 of reaction rate, in the initial step, and according to the number of M intermediate in a trimer unit, from three to one, the reaction rate of bacteriorhodopsin into M intermediates smaller as 1.73, 0.80, 0.19 which caused by influence of inter-molecular interaction between bacteriorhodopsin.

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