1,2,4-Trifluorobenzene, the decarboxylation product of 2,4,5-trifluorobenzoic acid, is an important raw material for synthesizing sitagliptin phosphate, the main medicinal treatment for diabetes. The traditional synthesis suffers from environmental concerns; therefore, in this work, a series of metal catalysts was employed to catalyze the decarboxylation of 2,4,5-trifluorbenzoic acid in NH3-enriched high-temperature liquid water (HTLW) to address these concerns. Copper catalysts exhibited excellent performance, and heterogeneous copper catalysts, such as Cu and Cu2O, led to a higher yield of 1,2,4-trifluorobenzene (89.1%) than homogeneous copper catalysts, such as CuCl2 and CuCl. The effects of catalyst loading and reactant loading on the decarboxylation of 2,4,5-trifluorbenzoic acid were also investigated. Increases in the catalyst and reactant loadings were favorable for the decarboxylation of 2,4,5-trifluorbenzoic acid; however, a high catalyst loading was not favorable. A reusability test with Cu2O revealed that Cu2O has excellent activity maintenance in NH3-enriched HTLW.

The hydrothermal decomposition reactions of cellulose, glucose, and fructose were catalyzed by ionic liquids (ILs) to produce levulinic acid (LA). Among 18 types of ionic liquids with different anions, the ionic liquids containing haloids and hydrogen sulfates exhibited a universal activity for the conversion of fructose, glucose, and cellulose to produce LA. Reusability tests for [PrSO3HMIm]Cl and [BSO3HMIm]HSO4 were carried out and revealed that [BSO3HMIm]HSO4 can be used over four cycles without a loss of activity. The effects of reactant loading, ionic liquid loading, reaction temperature, and time on the decomposition of glucose and cellulose were investigated with [BSO3HMIm]HSO4. The optimum reaction conditions were obtained as a [BSO3HMIm]HSO4 loading of 0.5 g, a reactant loading of 0.05 g, a temperature of 180 °C, and a reaction time of 1 h. Yields of 60.8% from glucose and of 54.5% from cellulose were obtained for the catalysis with [BSO3HMIm]HSO4. Kinetics studies of the decomposition of glucose and cellulose were conducted. The rate constants at each temperature were obtained. For the decomposition of glucose, the activation energies for the conversion of glucose to LA and conversion of glucose to humins were determined as 121.1 ± 4.7 kJ/mol and 114.6 ± 6.1 kJ/mol, respectively. For the decomposition of cellulose, the activation energies for the conversion of cellulose to glucose, conversion of glucose to LA, and conversion of glucose to humins were determined as 186.8 ± 7.4 kJ/mol, 114.0 ± 2.7 kJ/mol, and 148.3 ± 11.2 kJ/mol, respectively.

•Extraction of lipids from three wet algal species.•Using [BMIM][HSO4] as a solvent for the extraction.•Microwave-assisted heating to enhance the extraction.•Accelerated the extraction rate by more than 370%.•Detailed analysis of extraction product.A study of microwave-assisted extraction of lipid from three algal species in 1-butyl-3-methylimidazolium hydrogen sulfate ([BMIM][HSO4]), an imidazolium-based ionic liquid, was performed by evaluating the effects of microwave irradiation and ionic liquid on the extraction. The experimental results indicated that microwave irradiation could promote the extraction rate over 15 times for Chlorella sorokiniana, several hundred percent for Nannochloropsis salina and over 10 times for Galdieria sulphuraria when compared with the conventional solvent extraction method. [BMIM][HSO4] was an effective ionic liquid for the extraction of lipid from algae. The mineral acids could enhance the extraction of lipid from algae using [BMIM][HSO4]. The lipid product distribution showed not much difference between different species of algae. [BMIM][HSO4] was very stable under the extraction conditions.

A solid polymer blend electrolyte system based on polyvinyl alcohol (PVA) and polyethylene glycol (PEG) complexed with NaClO4 was prepared using solution cast technique. The structural properties of these electrolyte films were examined by X-ray diffractrometry (XRD) studies. The XRD data revealed that the amorphous domains of polymer blend matrix increased with increase of sodium salt concentration. The complexation of the salt with the polymer blend was confirmed by Fourier transform infrared (FTIR) studies. DC conductivity of the films was measured in the temperature range 303–398 K. The electrical conductivity increased with increasing dopant concentration, which is attributed to the formation of charge transfer complexes. The electrolyte exhibited the highest room temperature conductivity 2.41 × 10−6 S cm−1 at 30 % of NaClO4 salt concentration. The polymer complexes exhibited Arrhenius-type dependence of conductivity with temperature. In the temperature range studied, two regions with different activation energies were observed. Electrochemical cells of configuration Na/(PVA + PEG + NaClO4)/(I2 + C + electrolyte) were fabricated and the discharge characteristics of these cells were studied under a constant load of 100 K. Several cell parameters associated with the cells were evaluated and compared with earlier reports. UV-VIS absorption spectra in wavelength region 200–600 nm were used to evaluate the optical properties like direct band gap, indirect band gap and absorption edge. The optical band gaps decreased with increasing sodium ion concentration. This suggests that NaClO4 is a good dopant to improve the electrical properties of PVA + PEG polymer blend electrolytes.

•Aviation fuels can be synthesized directly from microalgae lipids in water over Pt/C.•Pt/C is capable for decarboxylation of all test model compounds of microalgae lipids.•Pt/C keeps the catalytic activity on decarboxylation even at the third use.•Mechanism of direct decarboxylation of fatty acid esters is proposed.•Optimum reaction condition for decarboxylation of methyl stearate is obtained.In this contribution, we confirmed that aviation fuels could be synthesized directly from microalgae lipids in water over a Pt/C catalyst without additional hydrogen. After decarboxylation at 330 and 370 °C for 120 min, the oxygen content in the microalgae lipids was significantly reduced and the heating value of produced aviation fuels was greatly increased. The reaction mechanism of direct decarboxylation of microalgae lipids to aviation fuels was further investigated using each of the representative compounds in microalgae lipids, such as methyl laurate, methyl eicosanoate, methyl stearate, ethyl stearate, and tristearin as the starting material in separate reactions under the same conditions. Those reaction conditions, solvent, water loading, catalyst loading and reactant loading, were optimized. It was concluded that among the tested solvents, water was the most favorable for the selective decarboxylation of methyl stearate, that the catalytic decarboxylation rate of fatty acid esters with larger carbon numbers in water was faster than those with smaller carbon numbers, and that the Pt/C catalyst retained its activity through its third use. These results provide new insights for the direct decarboxylation of microalgae lipids to aviation fuels.

•Synthesis and optimization of pore texture of mesoporous carbons.•Synthesis and characterization of 16 ordered mesoporous carbon samples.•Effective adsorption of berberine hydrochloride on mesoporous carbons.•Effect of soft template to hard template on pore textural properties of the carbons.•Relationship between adsorption amount and carbon pore textural properties.Sixteen mesoporous carbon adsorbents were synthesized by varying the ratio of soft to hard templates in order to optimize the pore textural properties of these adsorbents. The mesoporous carbon adsorbents have a high BET specific surface area (1590.3–2193.5 m2/g), large pore volume (1.72–2.56 cm3/g), and uniform pore size distribution with a median pore diameter ranging from 3.51 nm to 4.52 nm. It was observed that pore textural properties of the carbon adsorbents critically depend on the molar ratio of carbon sources to templates, and the hard template plays a more important role than the soft template in manipulating the pore textures. Adsorption isotherms of berberine hydrochloride at 303 K were measured to evaluate the adsorption efficacy of these adsorbents. The adsorption of berberine hydrochloride from aqueous solutions on the sixteen mesoporous carbon adsorbents synthesized in this work is very efficient, and the adsorption equilibrium capacities on all samples are more than double the adsorption capacities of berberine hydrochloride of the benchmark adsorbents (polymer resins and spherical activated carbons) at similar conditions. It was observed from the adsorption experiments that the equilibrium adsorption amounts of berberine hydrochloride are strongly correlated with the BET specific surface area and pore volume of the adsorbents. The adsorbent with the highest BET of 2193.5 m2/g displayed the largest adsorption capacity of 574 mg/g at an equilibrium concentration of 0.10 mg/mL of berberine hydrochloride in an aqueous solution.Graphical abstract

A systematic study of microwave-assisted degradation of lignin model compounds such as benzyl phenyl ether (BPE) and guaiacol, in imidazolium-based ionic liquids, was performed by evaluating the catalytic activity of 29 types of ionic liquids as both solvent and catalyst. After measuring and comparing the acidity of each ionic liquid solution for BPE and guaiacol degradation under the microwave irradiation and conventional heating conditions, it was found that the ionic liquid 1-butyl-3-methylimidazolium hydrogen sulfate ([BMIM]HSO4) was the most effective for decomposing the lignin model compounds. The experimental results indicate that ionic liquid acidity is in favor of the catalytic activity for BPE and guaiacol degradation, microwave irradiation could accelerate the degradation rate by 650% for BPE and 1120% for guaiacol and significantly increase the reaction selectivity. It was also found in experiments that the ionic liquid [BMIM]HSO4 could be used for 5 times without any loss of catalytic activity. The possible mechanisms for BPE and guaiacol degradation are proposed based on the product distributions.

In this contribution, a novel solvent system for the crystallization of asiaticoside from total triterpenoid saponins of Centella asiatica was established by utilizing the difference between the induction periods of madecassoside and asiaticoside. Asiaticoside could be separated from the mixture of asiaticoside and madecassoside by crystallization with about 80% yield and 95% purity. The mechanism behind the significantly different induction periods of asiaticoside and madecassoside in the methanol + water system is also proposed. Crystallization of asiaticoside from total triterpenoid saponins of Centella asiatica achieved a maximum yield of 60% with 70% purity. A recrystallization was carried out to obtain 76% yield with 91% purity. The optimized conditions for the crystallization of asiaticoside from total triterpenoid saponins of Centella asiatica were determined.

•[BMIM][DBP] showed a remarkable entrainer performance for the separation of acetic acid from aqueous solution.•Isobaric binary + ternary VLE data measured at 101.32 kPa.•The parameters of NRTL model for the binary systems were obtained.The removal and recycling of acetic acid from acetic acid + water mixture has a great significance for environmental protection and resource utilization. After the addition of ionic liquid (IL) 1-butyl-3-methylimidazolium dibutylphosphate [BMIM][DBP], the boiling point difference of the water + acetic acid system increased from 17.88 K (0 mass % IL) to 41.13 K (about 59 mass % IL), and the relative volatility (x1′ = 0.9) increased from 1.60 (0 mass % IL) to 9.81 (about 57 mass % IL). [BMIM][DBP] showed a remarkable entrainer performance for the separation of acetic acid from aqueous solution. In this work, Isobaric vapor-liquid equilibrium (VLE) data of the systems water + acetic acid, water + [BMIM][DBP], acetic acid + [BMIM][DBP], and water + acetic acid +  [BMIM][DBP] were determined at 101.32 kPa by using an improved Rose–Williams equilibrium still. Based on the chemical theory and Hayden–O’Connell (HOC) method, the parameters of NRTL model for the binary systems were obtained, and the predicted values of the ternary systems of water + acetic acid + [BMIM][DBP] fitted the experimental VLE data well.The effect of ionic liquid 1-butyl-3-methylimidazolium dibutylphosphate [BMIM][DBP] on the vapor-liquid equilibria of water+acetic acid at 101.32 kPa.

The removal and recycling of acetic acid from aqueous solutions is important for environmental protection and resource utilization. In this work, ionic liquid (IL) 1-ethyl-3-methylimidazolium diethylphosphate ([EMIM][DEP]) as an entrainer for the extractive distillation of the system water + acetic acid was investigated. Isobaric vapor–liquid equilibrium (VLE) data of the systems acetic acid + water, water + [EMIM][DEP], acetic acid + [EMIM][DEP], and water + acetic acid + [EMIM][DEP] have been measured at 101.32 kPa by using an improved Rose–Williams equilibrium still. The addition of [EMIM][DEP] showed a remarkable entrainer performance for the separation of acetic acid from its aqueous solution. The boiling point difference of the water + acetic acid system increased from 17.88 K (0 wt % IL) to 42.41 K (about 50 wt % IL), and the relative volatility (x1′ = 0.9) increased from 1.60 (0 wt % IL) to 5.28 (about 50 wt % IL). On the basis of the chemical theory and the Hayden–O’Connell (HOC) method, the parameters of the NRTL model for the binary systems were obtained, and the predicted values of the ternary systems of water + acetic acid + [EMIM][DEP] fitted the experimental VLE data well.

•Synthesis and characterization of the ordered mesoporous carbon.•Effective adsorption of berberine hydrochloride, colchicine, and matrine.•Adsorption equilibrium, kinetics, and breakthrough curves of three alkaloids.•Competitive adsorption of berberine hydrochloride, colchicine, and matrine from a mixture solution.An ordered mesoporous carbon (OMC) adsorbent was synthesized, characterized, and evaluated for effective separation and purification of alkaloid compounds from aqueous solutions. The OMC adsorbent has a large BET specific surface area (1532.2 m2/g), large pore volume (2.13 cm3/g), and narrow pore diameter distribution with a median pore diameter of 4.21 nm. Berberine hydrochloride, colchicine, and matrine were selected as the model compounds for evaluating the adsorption properties of the OMC adsorbent for alkaloid purification. Batch adsorption experiments of pure components in water were carried out to measure both adsorption equilibria and kinetics, and column breakthrough and desorption experiments were performed to validate the separation and regeneration efficacy of the OMC adsorbent. The adsorption equilibrium capacities of berberine hydrochloride, colchicine, and matrine on the OMC adsorbent at 0.100 mg/L and 298 K are 450, 600, and 480 mg/g, respectively, which are more than double the adsorption capacities of these compounds on two commonly used commercial resins (HPD300 and HPD100B) at similar conditions. Adsorption equilibrium of all three alkaloids could be obtained within 120 min at 298 K. The dynamic adsorption capacities determined from the breakthrough experiments are within 12% of the estimated equilibrium capacities from the Langmuir isotherms; and 74.3–92.8% of the adsorbed amounts could be recovered by desorbing with a 70% alcohol solution. The adsorption isotherms are analyzed with both Langmuir and Freundlich models, the adsorption kinetic data with the pseudo-first-order and pseudo-second-order models, and the breakthrough curves with four breakthrough models. The large adsorption capacity, fast adsorption rate, and easy regeneration make the ordered mesoporous carbon a promising adsorbent for adsorption and purification of alkaloid compounds from the extracts of herbal plants.Graphical abstract

The mixed-acid systems of four Lewis acids (FeCl3, CrCl3, ZnCl2, and CuCl2) combining three Brønsted acids (H2SO4, HCl, and H3PO4) were evaluated for the decomposition of glucose to produce levulinic acid (LA). The CrCl3–H3PO4 system had a strong synergic catalytic activity for the decomposition of glucose to LA. The effects of the ratio of CrCl3 and H3PO4 on glucose, fructose, and 5-hydroxymethylfurfural (5-HMF) decompositions were investigated. The mixed-acid system showed the strongest synergic catalytic activity for glucose, fructose, and 5-HMF decompositions when the ratio of CrCl3 in the CrCl3–H3PO4 system was 0.4–0.5. To probe the synergic catalysis mechanism of the CrCl3–H3PO4 system, the synergic catalytic activities of CrCl3–phosphates (KH2PO4, K2HPO4, and K3PO4) systems on glucose decomposition were also evaluated. The possible synergic catalysis mechanisms were proposed. This study provides insights for the synergic catalysis mechanism of hexose conversion to yield LA.

The kinetics and underlying mechanisms of the hydrothermal decomposition of the lignin model compounds anisole, diphenyl ether and phenethyl phenyl ether were studied. Whereas diphenyl ether was stable at hydrothermal conditions, anisole and phenethyl phenyl ether underwent hydrothermal decomposition between 260 and 290 °C. Experiments involving different initial reactant concentrations and different batch holding times revealed that hydrolysis of both anisole and phenethyl phenyl ether followed first-order kinetics. Experiments at different temperatures showed that the first-order rate constants displayed Arrhenius behavior, with activation energies of 149.8 ± 16.4 and 143.2 ± 21.0 kJ·mol–1 for anisole and phenethyl phenyl ether, respectively. A reaction mechanism is proposed for anisole, and reaction pathways for the decomposition of phenethyl phenyl ether are proposed based on the distribution of the products generated by hydrolysis. The reactivity of ether hydrothermal decomposition is discussed by reviewing the published conversion data of other ethers.

The adsorption properties (equilibrium, kinetics, and column breakthrough) of five model flavonoids (myricetrin, puerarin, naringin, rutin and neohesperidin dihydrochalcone) on selected macroporous resins were investigated in order to identify a suitable resin adsorbent for effective separation and purification of flavonoids from the extracts of herbal plants. It was observed that the resins with a low polarity and a high specific surface area have high adsorption capacities for all five flavonoids. Both the Langmuir and Freundlich isotherm equations correlate well the adsorption equilibrium data of the five flavonoids on four selected resins, and adsorption enthalpy, entropy, and free energy of the five flavonoids on HPD300 resin were calculated from the adsorption isotherms by the Freundlich equation constants. The pseudo-second-order adsorption rate equation fits the kinetic data on four selected resins better than the pseudo-first-order adsorption rate equation, and the initial adsorption rates were calculated and discussed. The HPD300 resin was selected as the most promising adsorbent for a preliminary separation and purification of flavonoids because of its excellent adsorption/desorption properties including high adsorption rates for all five flavonoids. The adsorption breakthrough experiment with a synthetic flavonoid mixture solution on the HPD300 resin further confirmed that the HPD300 resin can separate the five flavonoids effectively, especially for purifying neohesperidin dihydrochalcone from the flavonoid mixtures.

This research aims at identifying suitable resin adsorbents for efficient separation and purification of alkaloids from plant materials. The adsorption properties (equilibrium, kinetics, and column breakthrough) of four alkaloid model compounds (berberine hydrochloride, ligustrazine hydrochloride, colchicine, and matrine) on selected macroporous resins were studied. The adsorption equilibrium capacities and desorption ratios of the four model compounds on nine different macroporous resins were measured and compared. It was observed that the resins with a low polarity and high surface area offered a high adsorption capacity for all alkaloids. The pseudo-second-order adsorption rate equation fit well all the kinetic data, and the Langmuir and Freundlich isotherm equations correlate well the adsorption isotherms on the four resins. Among the nine resins studied in this work, the HPD300 resin was identified as the most promising adsorbent for alkaloids separation and purification because of its excellent adsorption and desorption properties for all four alkaloid compounds. The adsorption breakthrough experiment on the HPD300 resin using a mixture solution containing all four model compounds further confirmed the effective separation of alkaloids on the HPD300 resin.

One-pot preparation of methyl levulinate (MLA) from cellulose in near-critical methanol was studied. Acids containing SO3H group were proven to be effective catalysts for the production of MLA from cellulose’s catalytic alcoholysis. The effects of different reaction conditions, such as an initial cellulose concentration of 10–30 g/L, a temperature range from 170 to 190 °C, and a sulfuric acid concentration of 0.01–0.03 mol/L, on the production of MLA were investigated. The results showed the reaction temperature and acid concentration significantly affected the process of cellulose alcoholysis and the yield of MLA. A high yield of up to 55% MLA was achieved at 190 °C for 5 h, using 0.02 mol/L H2SO4 as a catalyst.

The solubilities of madecassoside in a mixture of methanol + water were determined in the temperature range from (298.15 to 328.15) K by a static analytical method. A “W”-type curve was found for the solubility of madecassoside in the mixture of methanol + water. The induction periods of asiaticoside and madecassoside in a mixture of methanol + water were determined at 298.15 K by a laser scattering method. The results show that the solubilities of madecassoside are similar to those of asiaticoside in the mixture of methanol–water excluding those at high water content and high temperature. However, these two compounds with the only difference of 6-OH exhibit a quite different crystallization property that the induction period of madecassoside is at least 10 times longer than asiaticoside. Moreover, the interfacial tension data of asiaticoside were obtained, which are in the range of (0.55 to 0.86) mJ·m–2.

The application of high temperature liquid water (HTLW) to decomposition of lignin as efficient and green solution for phenolic compounds recovery was studied. Benzyl phenyl ether (BPE), the lignin model compound, was treated at temperatures ranging from 220 to 250 °C. BPE undergo hydrolysis in HTLW, and main products were phenol and benzyl alcohol with the minimum selectivities of 75.7% and 82.8%, respectively. Lower temperature led to higher selectivity in 220–250 °C temperature range. The kinetics on BPE hydrolysis was studied and the activation energy was determined as 150.3 ± 12.5 kJ/mol with the first-order kinetic equations. Based on products distribution, the reaction mechanism for decomposition of benzyl phenyl ether was proposed. The investigated process provides insights into the design of a commercial method for utilization of lignin.

The solubilities of asiaticoside in water, methanol, ethanol, n-propanol, n-butanol, and a methanol + water mixture were determined over the temperature range from (278.15 to 343.15) K by a static analytical method. The concentrations of asiaticoside in the saturated solutions were analyzed by reverse-phase high-performance liquid chromatography. An “N”-type curve was found for the solubilities of asiaticoside in the methanol + water mixture. Two empirical equations were proposed to correlate the experimental data, which fit the data well.

The solubilities of nizatidine in water, methanol, ethanol, acetone, and ethyl acetate were determined in the temperature range from (273.15 to 343.15) K by a static analytical method. The concentrations of nizatidine in saturated solution were analyzed by reverse-phase high-performance liquid chromatography. An empirical equation was proposed to correlate the experimental data, which fit the data very well.

We report herein the first kinetics studies of hydrothermal decarboxylation of a fully halogenated benzoic acid and a heterocyclic aromatic diacid. Decarboxylation was the only reaction path observed, and there was no evidence of dehalogenation. Experiments at different initial reactant concentrations and different batch holding times revealed that both compounds exhibited first-order kinetics. Experiments at different temperatures showed that the first-order rate constants displayed Arrhenius behavior with activation energies of 157 kJ mol−1 for pentafluorobenzoic acid decarboxylation and 141 kJ mol−1 for quinolinic acid decarboxylation.

Kinetic study on the complexation of gallic acid with ferrous sulfate was performed using UV–Vis absorption spectroscopy. Under the experimental conditions, the stoichiometric composition of the formed complex is 1:1. The complexation reaction was found to be a second-order one. The influences of temperature, ionic strength and solvents on the complexation reaction were investigated. According to the Arrhenius equation, the apparent activation energy of the complexation reaction was evaluated to be 71.64 kJ × mol−1. A three-step reaction mechanism was proposed, which can well explain the kinetic results obtained.

The solubilities of 2,4-dihydroxybenzophenone, 2,3,4-trihydroxybenzophenone, 2,3,4,4′-tetrahydroxybenzophenone, and 2,2′,4,4′-tetrahydroxybenzophenone in an ethanol + water mixture were determined in the temperature range from (293.15 to 343.15) K by a static analytical method. The concentrations of the investigated polyhydroxybenzophenones in saturated solution were analyzed by reverse-phase high-performance liquid chromatography. A semiempirical equation was proposed to correlate the experimental data and exhibited good agreement.

High temperature liquid water (HTLW) has drawn increasing attention as an environmentally benign medium for organic chemical reactions, especially acid-/base-catalyzed reactions. Non-catalyzed hydrolyses of gallotannin and tara tannin in HTLW for the simultaneous preparation of gallic acid (GA) and pyrogallol (PY) are under investigation in our laboratory. In this study, the hydrolysis kinetics of gallotannin and tara tannin were determined. The reaction is indicated to be a typical consecutive first-order one in which GA has formed as a main intermediate and PY as the final product. Selective decomposition of tannin in HTLW was proved to be possible by adjusting reaction temperature and time. The present results provide an important basic data and reference for the green preparation of GA and PY.

In order to investigate the influencing factors of 5-hydroxymethyl-2-furaldehyde (5-HMF) content in Schisandra, confirm the theory of 5-HMF deriving mainly from Schisandra processing course, and give some suggestions about the Schisandra processing method, the 5-HMF contents in decoctions of Schisandra under different heating temperature, decocting time, soaking time, processing methods and treatment with different solvents before decocting the Schisandra were measured by RP-HPLC method. The results showed that there is great difference of 5-HMF level in decoctions from differently processed Schisandra and unprocessed Schisandra; decocting time of 60 min has some effects on 5-HMF level in decoctions and there is certain quantity 5-HMF in processed Schisandra itself and very little 5-HMF in unprocessed Schisandra. Heating time, heating temperature and treating solvents all have effect on 5-HMF level in decoction of Schisandra. 5-HMF in Schisandra was mainly from processing course. Both long heating time and high heating temperature can increase 5-HMF level in Schisandra. The production of 5-HMF in Schisandra may have some relationships with some polar components, which can dissolve in water, ethanol and acetone, especially in ethanol. To control processing temperature, processing time and treatment with some solvent is very important for controlling 5-HMF level in Schisandra.

The decomposition kinetics of glucose was studied in high-temperature liquid water (HTLW) from 180 to 220°C under a pressure of 10 MPa. It was found the main products from glucose decomposition were 5-hydroxymethylfurfural (5-HMF) and levulinic acid (LA). The decomposition kinetics of 5-HMF and stability of LA in HTLW were further investigated. A kinetic model for glucose decomposition was proposed accordingly. In the model, a series of first-order reactions with the consideration of parallel by-reactions were used to illustrate the decomposition of glucose. The decomposition activation energies of glucose, 5-HMF, and LA were evaluated as 118.85, 95.40, and 31.29 kJ·mol−1, respectively.