Kinetics Of Isomerization Research Articles

Sensitivity of Isomerization Kinetics of 1,3,5-Triphenylformazan on Cosolvents Added to Toluene.

Formazan molecules exhibit photochromism because isomerization processes following excitation may occur in both the azo group and the hydrazone group; thus, each formazan may be present in various forms with different colors. The ratio of these forms depends on the illumination conditions and the environment of the formazan with a most incisive sensibility of the thermal anti-syn relaxation of the C═N toward slight traces of impurities in toluene solutions, as reported most prominently for 1,3,5-triphenylformazan. Here, we study the latter compound with transient absorption spectroscopy to investigate the role of these traces by adding small amounts of both protic and aprotic cosolvents. Whereas the activation barrier decreases if the binary solvent mixture has a higher polarity, the role of hydrogen bonding can have a reverse impact on the thermal isomerization rate. Both the addition of an aprotic cosolvent and the addition of a protic cosolvent can slow the reaction due to their hydrogen-bond accepting and hydrogen-bond donating properties, respectively. In the case of methanol as a cosolvent, this effect outweighed that of the polarity increase for small concentrations, which was not observed for the fluorinated alcohol hexafluoroisopropanol. The results are explained in the context of a competition between solute-cosolvent and cosolvent-cosolvent hydrogen bonding.

Theoretical study on isomerization, decomposition and ring-closure reaction kinetics of methyl pentanoate radicals

A comprehensive study on the isomerization, decomposition and ring-closure reaction kinetics, as well as thermodynamic properties of methyl pentanoate radicals were carried out in this work. The M06–2X/cc-pVTZ level of theory was employed to optimize geometries and analyze frequencies for all the stationary points on the potential energy surfaces. The CCSD(T) method with two basis sets, cc-pVDZ and cc-pVTZ, was used to calculate single point energies, which were further extrapolated to the complete basis set (CBS) limit to construct the potential energy surfaces. The energy calculation results indicated that isomerization of δ-R to α-R, decomposition of γ-R to CH2C(=O)OCH3 and propene, and ring-closure reaction of δ-R to 1-methoxycyclopentanoxyl radical are the most energetically favored reactions among the studied isomerization, decomposition and ring-closure reaction channels, respectively. High pressure limit, and temperature and pressure dependent rate coefficients were determined by solving the one-dimensional energy-dependent master equations with Tsinghua University Minnesota Master Equation program (TUMME). The rate coefficients and branching ratios were found to be significantly affected by temperature and pressure. The decomposition reactions yielding small unsaturated esters or small ester radicals dominate at high temperatures, while the isomerization reactions proceeding via five- and six-membered ring saddle points, as well as the ring-closure reactions play more important roles at low temperatures. Significant discrepancies are observed between the theoretically calculated rate coefficients and estimated results. The thermochemical properties of methyl pentanoate radicals were calculated using isodesmic reaction method and atomization method together with the multistructural torsional anharmonicity partition functions. This study provides accurate kinetic and thermodynamic data on methyl pentanoate radicals, which are expected to advance our understanding of combustion chemistry of methyl pentanoate and larger methyl esters.

Synthesis and Characterization of Thin Films Based on Azobenzene Derivative Anchored to CeO2 Nanoparticle for Photoswitching Applications

Azobenzene has attracted substantial attention as a photoswitchable molecule since its applications range from energy and data storage to biomedical applications. This work reports a new type of thin-film based on azobenzene derivative anchored to cerium oxide nanoparticles CeO2 NPs for photoswitching applications. The trans-cis isomerization and reverse isomerization occur by UV-light exposure and thermal relaxation process, respectively. The photoisomerization and reverse isomerization kinetics for CeO2 NPs-MR thin films are studied, investigated, and analyzed using UV-Vis absorbance spectra, FTIR spectroscopy, XRD, and scanning electron microscopy (SEM), in addition to differential scanning calorimetry (DSC) measurement to study the energy storage capacity. The results found that anchoring azobenzene to CeO2 NPs is successful in multisource storage of solar energy applications.

Photoswitchable Composite Polymer Electrolytes Using Spiropyran-Immobilized Nanoporous Templates.

Composite polymer electrolytes (CPEs) with smart, stimuli-responsive characteristics have gained considerable attention owing to their noninvasive manipulation and applications in future technologies. To address this potential, in this work, we demonstrate photoresponsive composite polymer electrolytes, consisting of gel polymer electrolyte (GPE) and spiropyran-immobilized nanoporous anodic aluminum oxide (SP-AAO) templates. Under UV irradiation, the close SP form isomerizes to the open merocyanine (MC) form, creating extremely polarized AAO surfaces; whereas, under visible light irradiation, the MC form reverts to the SP form, creating neutral surface conditions. The electrostatic interactions between ions and AAO surfaces are investigated by attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy. Moreover, the behavior of ionic conductivity of the GPE@SP-AAO is found to be consistent with the kinetics of isomerization tracked by UV-Vis spectroscopy. This work provides a promising platform for developing next-generation photoelectronic smart devices.

Studies on kinetics of isomerization of gamma oryzanol at air-water interface

We report the studies on Langmuir monolayer of gamma oryzanol (γ-Or) in trans and cis states and kinetics of photo-isomerization and thermal isomerization of γ-Or at air-water interface. The surface manometry studies show that the monolayer of trans−γ-Or on compression exhibits gas and liquid expanded phases with a small region of gas-liquid expanded coexistence region. The monolayer collapses at a surface pressure of 34 mNm−1. In contrast to this, the cis−γ-Or monolayer on compression exhibits an extended gas-liquid expanded coexistence region between gas and liquid expanded phases before collapsing at a surface pressure of 38 mNm−1. The studies on isomerization of γ-Or in the Langmuir monolayer show that the photo-isomerization process follows first order kinetics and thermal isomerization follows second order kinetics. The rate constants of photo-isomerization and thermal isomerization of γ-Or at air-water interface obtained at different temperatures show Arrhenius temperature dependence. The activation energy for the photo-isomerization was found to be 85.34 kJ/mol and for thermal isomerization it was found to be 51.33 kJ/mol.

Dual-tautomerism separation method based on asymmetric transformation: Gram-scale preparation of high-purity punicalagin from pomegranate peel wastes

In this study, a special orthogonal separation method, named as dual-tautomerism separation (DTS), was developed for the purification of tautomeric compounds from complex matrixes. In DTS, isomers of these compounds are individually collected and asymmetrically transformed to the mixtures of isomers. After separating the mixture with an identical method, high-purity compounds can be prepared from the newly generated isomers but impurities remain in another one. To validate the effectiveness, a DTS was developed to prepare punicalagin in gram-scale from pomegranate peel waste. Isomerization kinetic and thermodynamic of punicalagin were accurately assayed by dynamic HPLC built on low-temperature or/and loop-based stop-flow two-dimensional liquid chromatography. After the isomerization based on it, 9.3 g of pomegranate peel extract was firstly separated on C18 column, and Fα and Fβ around α-punicalagin and β-punicalagin were obtained. Then, the proportion of α-punicalagin in Fα and Fβ was optimized to 52.7% and 32.0% based on isomerization kinetics and thermodynamic. With the aid of low-temperature injection, Fα and Fβ were loaded and secondly purified. After waste recycling, totally 3.0 g of punicalagin with the purify of 99.5% was obtained within two days, which would strongly support the resource utilization of pomegranate peel waste. Because only an individual method was employed in the two-step purification, the separation in DTS was fully compatible.

Engineering Next Generation Cyclized Peptide Ligands for Light‐Controlled Capture and Release of Therapeutic Proteins

AbstractPhoto‐affinity adsorbents (i.e., translucent matrices functionalized with ligands featuring light‐controlled biorecognition) represent a futuristic technology for purifying labile biologics. In this study, a framework for prototyping photo‐affinity adsorbents comprising azobenzene‐cyclized peptides (ACPs) conjugated to translucent porous beads (ChemMatrix) is presented. This approach combines computational and experimental tools for designing ACPs and investigating their light‐controlled isomerization kinetics and protein biorecognition. First, a modular design for tailoring ACP's conformation, facilitating sequencing, and streamlining the in silico modeling of cis/trans isomers and their differential protein binding is introduced. Then, a spectroscopic system for measuring the photo‐isomerization kinetics of ACPs on ChemMatrix beads is reported; using this device, it is demonstrated that the isomerization at different light intensities is correlated to the cyclization geometry, specifically the energy difference of trans versus cis isomers as calculated in silico. Also, a microfluidic device for sorting ACP‐ChemMatrix beads to select and validate photo‐affinity ligands using Vascular Cell Adhesion Molecule 1 (VCAM‐1) as target protein and cycloAZOB[GVHAKQHRN‐K*]‐G‐ChemMatrix as model photo‐affinity adsorbent is presented. The proposed ACPs exhibit rapid and defined light‐controlled isomerization and biorecognition. Controlling the adsorption and release of VCAM‐1 using light demonstrates the potential of photo‐affinity adsorbents for targets whose biochemical liability poses challenges to its purification.

Understanding the pathway and kinetics of aspartic acid isomerization in peptide mapping methods for monoclonal antibodies.

Isomerization of aspartic acid (Asp) in therapeutic proteins could lead to safety and efficacy concerns. Thus, accurate quantitation of various Asp isomerization along with kinetic understanding of the variant formations is needed to ensure optimal process development and sufficient product quality control. In this study, we first observed Asp-succinimide conversion in complementarity-determining regions (CDRs) Asp-Gly motif of a recombinant mAb through ion exchange chromatography, intact protein analysis by mass spectrometry, and LC-MS/MS. Then, we developed a specific peptide mapping method, with optimized sample digestion conditions, to accurately quantitate Asp-succinimide-isoAsp variants at peptide level without method-induced isomerization. Various kinetics of Asp-succinimide-isoAsp isomerization pathways were elucidated using 18O labeling followed by LC-MS analysis. Molecular modeling and molecular dynamic simulation provide additional insight on the kinetics of Asp-succinimide formation and stability of succinimide intermediate. Findings of this work shed light on the molecular construct and the kinetics of the formation of isoAsp and succinimide in peptides and proteins, which facilitates analytical method development, protein engineering, and late phase development for commercialization of therapeutic proteins.

Isomerization of Aspartyl Residue in Amyloid Beta Fragments: The Kinetics by Real-Time 1H NMR Under Neutral and Basic Conditions

Isomers of aspartyl (Asp) residues have been found in various proteins in aged human tissues. Isomerization of Asp is considered as one of the potential factors to facilitate amyloidosis via the oligomerization of amyloid beta (Aβ) peptides. It is still challenging to analyze such isomerization in real time, and no information has been provided about Asp isomerization in situ. In this work, we report a real-time quantitation of the isomerization at Asp in Aβ fragment peptides, Aβ2−9 (A2EFRHD7SG9) and Aβ2−16 (A2EFRHD7SGYEVHHQK16) by using solution-state 1H NMR in situ. The simultaneous NMR detection of isomerization product and reactant enables us to compare how fast Asp is converted to isoAsp in terms of the kinetics of isomerization in real time. In Aβ2−9, the rate constant, k of the increase of isoAsp7 was almost parallel with the decrease of Asp7; the rate constants were estimated to be (1.3 ± 0.1) × 10−3 h−1 for Asp7 decrease and (1.2 ± 0.1) × 10−3 h−1 for the increase of isoAsp7 at 70 °C. In Aβ2−16, however, k of isoAsp7 increase was much less than the Asp7 decrease. This is due to an inhibitory effect of histidine (His) on the progress of Asp isomerization; the coupling of His imidazole ring with a succinimide (Suc) intermediate makes Suc lifetime longer enough to interfere with the conversion to isoAsp.

Multi-factor optimization of canola oil deodorization parameters and evaluation of linolenic acid isomerization kinetics during pilot-scale deodorization

In this study, neutralized and bleached canola oil, deodorized according to the central composite design consisting 30 experiments with differing levels of deodorization temperature, pressure, stripping steam rate and duration to optimize process parameters and evaluate isomerization kinetics of linolenic acid. Free fatty acid (FFA) content, oxidation stability index (OSI), peroxide value, total polar compounds, tintometric redness, fatty acid composition of every deodorized canola oil sample were measured. Deodorization parameters were optimized by aiming the lowest FFA, trans-linolenic acid (tr-C18:3) content, highest OSI value and polyunsaturated fatty acid (PUFA) content via response surface methodology. Optimum temperature, pressure, stripping steam, and duration were calculated as 228.8 °C, 1.4 mBar, 1.25 g/min and 80 min, respectively. FFA level, OSI, tr-C18:3 content, and PUFA content was predicted as 0.044%, 10.65 h, 0.21% and 30.50% by the optimization model. The relative difference between the results of the validation experiments and optimization model predictions was differed between 7.04 and 14.49%. Temperature and duration of deodorization were found significantly effective (p < 0.05) on trans isomerization of linolenic acid according to ANOVA, therefore reaction rate constants of tr-C18:3 formation and cis-linolenic acid (cis-C18:3) degradation were calculated with Arrhenius’ equation using graphical method. Activation energies were calculated with Arrhenius’ equations as 346 kJ/mol for cis-C18:3 deterioration (R2 = 0.92) and 183 kJ/mol for tr-C18:3 formation (R2 = 0.99). Cis-C18:3 degradation and tr-C18:3 formation rates were found as 0.0032 min−1 and 0.0014 min−1 at 220 °C, 0.0049 min−1 and 0.0024 min−1 at 225 °C, 0.0172 min−1 and 0.0034 min−1 at 230 °C, respectively.

Insight into relation between optically-switched foam stability and isomerization kinetic from azobenzene-based sulfate surfactant

The optical-switching foam can meet the different foam property requirements in industrial process. Anionic photo-responsive surfactant is more likely to produce the stable foam and to achieve a larger range of foam stability regulation. However, the foam half-life (t1/2) of photo-responsive foam agent upon the light irradiation is difficult to be predicted, limiting its accurate control at an untested condition. An optically-switched azobenzene surfactant, 4-butoxy-4′-sulfate ethoxy azobenzene (BSEAzo), is designed and synthesized for utilization as a foam controller. Insights to bulk and interface isomerization kinetics (k), the surface activities and foam properties are presented. The maximum surface tension difference (Δγ) between trans and cis isomer reach 12 mN m−1. BSEAzo exhibits rapid isomerization and excellent cycle stability by alternating light irradiations, and molecular adsorption is varied remarkably at the interface. Foam half-life under visible (Vis) and ultraviolet (UV) lights is recorded, showing a wide foam stability regulation (from 141 s to 34 s). Interestingly, a proportional relation between foam half-life and 1/k is established in the range of 0.5–2.5 g L−1, due to interface isomerization is as a determination factor of foam stability control. It is possible to provide a promising theoretical calculation to guide the foam controllability accurately.

High catalytic performance of 2D Ti3C2Tx MXene in α-pinene isomerization to camphene

This work demonstrates a catalytic activity of MXene materials in the isomerization of α-pinene. The temperature influence, catalyst content and reaction time on α-pinene conversion have been revealed. Furthermore, the selectivity of transformation to appropriate products have been investigated. The multilayered and exfoliated Ti3C2Tx have been examined. Both studied MXene materials were active in α-pinene isomerization. However, the exfoliated Ti3C2Tx increased the activity significantly. As a result, an outstanding 100 mol% conversion of α-pinene in 7 h was achieved. It was observed that at optimal operating conditions and catalyst content the selectivity resulted in ∼ 60 mol% toward camphene formation. Additionally, the kinetics of the process has been described. Here, the analysis indicates that the kinetics of α-pinene isomerization over MXene samples was described by first-order kinetics. To the best of our knowledge, it is the highest reported selectivity and conversion reported in the current state of the art.

Olefin esterification on Amberlyst® 15 catalyst: does the esterification site defy thermodynamics?

Kinetics for the reaction between 1-tetradecene and heptanoic acid to make tetradecyl heptanoates on dry Amberlyst® 15 catalyst at 90 °C are extremely complex. Observed kinetics of simultaneous double bond isomerization and esterification cannot be reconciled with a single type of catalytic site. Esterification and most of the double bond isomerization must occur on separate sites. Relative rates of esterification for tetradecene isomers suggest that adsorption coefficients on the esterification sites follow 1-tetradecene > 2-tetradecene > 3+-tetradecenes. These relative adsorption coefficients imply that, on this esterification site, 2-tetradecene isomerizes to 3-tetradecene faster than 3-tetradecene isomerizes to 2-tetradecene or 4-tetradecene, a truly novel finding not previously reported for any other acidic site. The site where most of the double bond isomerization occurs does not display this behavior, and isomerization of linear tetradecenes proceeds to thermodynamic equilibrium. Kinetic data indicate that esters form when carboxylic acid traps rapidly isomerizing carbenium ions on the catalyst’s surface. Competition is fierce for esterification sites among olefins, carboxylic acid, and esters, and olefins occupy few esterification sites. Contrastingly, olefins triumph in competition for isomerization sites, and olefin isomerization is much faster than esterification. Heptanoic acid exists primarily in dimer form, but the monomer form reacts to make esters. A complex kinetic model fit experimental data for double bond isomerization, conversion of olefin to esters, and the distribution of secondary esters that formed over 22 h.

Reaction kinetics of hydrogen shift isomerization of 1-hexyl radicals

Isomerization reactions form an important class of alkyl reactions. In this work, the kinetics of five types of 1-hexyl radical hydrogen shift reactions, i.e. 1-2, 1-3, 1-4, 1-5 and 1-6 hydrogen shift reactions, were investigated. The electronic structure calculations were performed by M06-2X/6-311 + G(2df,2p), and the high-pressure limit rate constants were obtained by using the conventional transition state theory including the multi-structural torsional anharmonicity and tunneling corrections with the Eckart approximation. The calculated rate coefficients of 1-hexyl radical 1-5 hydrogen shift isomerization agree very well with literature experimental data, which validates our methods. The results show that the 1-5, 1-6, 1-4 hydrogen shift reactions dominate in the low temperature region, and the multi-structural torsional anharmonicity factors of the five 1-hexyl radical isomerization reactions vary from 0.03 to 1.12 and reduce with the increasing ring structure size of the transition states.

Protonation of Ferrocene Derivatives with Strong Acids. Kinetic Relationships of the Redox Isomerism of Ferrocenylcarbenium Ions

The kinetics of redox isomerization of ferrocenylcarbenium ions obtained via protonation of ferrocene derivatives with perchloric acid in dioxane has been studied by means of electron absorption spectroscopy method from accumulation of ferrocenium cations. It has been shown that the dependences of the rate of ferrocenium cations accumulation on the components concentration is extremal in certain cases and is determined by the nature of metal complex and the initial ratio of the metal complex and acid. Stabilization of carbocations via their solvation with acetonitrile, DMF, and DMSO as well as via coordination with the starting compound leads to partial or complete loss of their ability to redox isomerization. Schemes of the metal complexes protonation and results of their kinetic analysis confirming the obtained concentration dependencies are given.

Poly(amic acid)s vs. polyimides with π-conjugated –N[dbnd]N- units: Cis-trans isomerization reaction and kinetics of thermal imidization

The paper describes the synthesis and characterization of “T-type” polyimides and their precursors – poly(amic acid)s. Investigated polymers contained azobenzene derivatives with no substituent or with fluorine atom in para position to the NN linkage. The influence of the main chain architecture (open or close imide rings), location and content of azo chromophores in polymers chains on physicochemical properties were studied. To the best of our knowledge, for the first time, the cis-trans isomerization reaction was studied for azo poly(amic acid)s, that was 1–18% after 3-minutes of 405 nm-light irradiation. Poly(amic acid)s characterized higher stability of isomerization than their polyimide counterparts. The studied azo polyimides showed high glass transition temperatures (174–206 °C) and high thermal stability with the beginning of the decomposition at 246–345 °C. The imidization kinetic of the studied poly (amic acid)s were investigated by differential scanning calorimetry (DSC) using Kissinger and Ozawa models. It was found that the studied azo polymers characterized high activation energies (275.4–357.1 kJ mol−1) and frequency factors (6.5 × 1029–1.3 × 1037 s−1).

A theoretical investigation on the mechanism and kinetics of the thermal isomerization of Trimethylsilylcyclopropane using CBS-QB3

The kinetics of the thermal isomerization of trimethylsilylcyclopropane in the temperature range of 689.5–751.1 K have been theoretically studied using Rice-Ramsperger-Kassel-Marcus (RRKM) theory and transition state theory (TST) in conjugation with CBS-QB3 calculations. Three possible reaction pathways are identified. Among them, the three-membered ring opening and hydrogen atom transfer to the carbon atom bonded to the SiMe3 group and formation of the allyltrimethylsilane is the main reaction. Our calculated kinetic rate constants appear to be in excellent agreement with the available experimental data. The results show that the most abundant product derived from Trimethylsilylcyclopropane will be the (Z)-1-propenyltrimethylsilane under thermodynamic control, while the most favorable process is isomerization reaction of that reactant into the allyltrimethylsilane from a kinetic viewpoint. The regioselectivity of the reaction decreases with decreasing pressures and increasing temperatures. In proportion to greater barrier heights, pressures P > 10−4 bar are in general enough for confirming saturation of the calculated rate coefficients compared with the high-pressure limit of the RRKM rates.

δ-Azaproline and Its Oxidized Variants.

Peptides featuring backbone N-amino substituents exhibit unique conformational properties owing to additional electrostatic, hydrogen-bonding, and steric interactions. Here, we describe the synthesis and conformational analysis of three δ-azaproline derivatives as potential proline surrogates. Our studies demonstrate stereoelectronic tuning of heterocyclic ring pucker, cis/trans amide propensity, and amide isomerization barriers within a series of oxidation state variants. A combination of NMR, X-ray diffraction, and density functional theory calculations shows that electron density and hybridization at the δ position play a dominant role in the conformational preferences of each analogue. Both δ-azaproline and γ,δ-dehydro-δ-azaproline exhibit strong trans amide rotamer propensities irrespective of ring conformation, while a novel residue, γ-oxo-δ-azaproline, features rapid amide isomerization kinetics and isoenergetic amide bond geometries influenced by torsional strain and H-bonding interactions. The introduction of the δ heteroatom in each residue allows the decoupling of structural effects that are typically linked in proline and its pyrrolidine-substituted analogues. δ-Azaproline derivatives thus represent useful probes of prolyl amide isomerism with potential applications in peptidomimetic drug design and protein folding.

Z-E isomerization of azobenzene based amphiphilic poly(urethane-urea)s: Influence on the dynamic mechanical properties and the effect of the self-assembly in solution on the isomerization kinetics

Azobenzene containing polymers have been used in the development of materials and devices responsive to light, devices for optical storage information, with shape-changing and shape-memory capacities, surface-relief grating, holograms, etc. Poly(urethane-urea)s (PUU) based on a hydrophilic polyethylene glycol (PEG-PUU), on a hydrophobic polycaprolactone diol (PCL-PUU) polyols, and on an equimolar mixture of them (PEG/PCL-PUU), 4,4′-diphenylmethane diisocyanate and 4,4′-diaminoazobenzene (DAAB), as a chain extender, were synthesized by a two-step route. PUU were characterized with respect to their chemical structure, molar masses, thermal and dynamic mechanical properties, and spectroscopic properties. The kinetics of the photo- and thermal-induced isomerization were studied in DMF solutions. The isomerization rate constant was two orders of magnitude higher for DAAB compared with PUU in DMF solution, except for PEG/PCL-PUU, for which the rate constant was half the value observed for DAAB. The amphiphilic nature of the PUU resulted in aggregates in DMF and, therefore, the azo isomerization for PEG-PUU and PCL-PUU occurred in a solid-state-like environment. On the other hand, PEG/PCL-PUU presented unimers and aggregates in DMF and the isomerization of azo groups in free PUU chains was faster. The PUU were semicrystalline and thermo-mechanically stable up 150 °C due to the hydrogen bonding involving urea, urethane and ester groups. The aggregates size in DMF solution, as well as the dynamic mechanical properties of the PUU, were sensitive to photo- and thermo-induced isomerization.

Isomerization Kinetics of Glucose to Fructose in Aqueous Solution with Magnesium‐Aluminum Hydrotalcites

AbstractMg−Al hydrotalcites for catalyzing glucose isomerization to fructose are prepared. Effects of atom ratios of Mg/Al ranging from 1 to 4 and calcination temperatures from 250–650 °C on catalytic performance were examined systematically. It was found that the hydrotalcite (Mg2Al1LDH) calcined at 450 °C with an atom ratio of Mg/Al=2 is an excellent catalyst for glucose isomerization. Characterizations by SEM, EDS, TEM, XRD, FTIR, TG and BET demonstrated that the formed oxide condensed phase as well as the interaction with the alumina helps promote glucose isomerization reaction due to their appropriate basic sites at high calcination temperature. With Mg2Al1‐450 as the catalyst, kinetic model analysis confirmed that the reaction of glucose isomerization to fructose was an exothermal reversible reaction; both the forward and reverse reactions are quasi‐first‐order reactions with activation energies of 71.82 kJ/mol and 48.15 kJ/mol, respectively, while the side reaction is a zero‐order reaction with an activation energy of 94.22 kJ/mol. Therefore, high isomerization reaction temperature is not beneficial to enhance the yield and selectivity of fructose.