Critical Review on the Synthesis of Levulinate Esters from Biomass-Based Feedstocks and Their Application

As one of the substitutes for traditional fossil energy, the biomass resource has attracted extensive attention. Levulinate esters (LEs) are important green and high value-added chemical molecules. Catalytic routes based on acid catalysts are developed for the production of levulinate esters from various biomass-derived materials. In this review, the catalytic route for preparation of levulinate esters from C5/C6 carbohydrates is summarized. The effects of homogeneous and heterogeneous acid systems on the levulinate ester yields and the catalyst recyclability were expounded. The effect of reaction solvents and heating methods on LE selectivity was presented. Given the apparent differences in the synthesis of LEs with different heating methods in current publications, current challenges and prospects for the synthesis of LEs from biomass-derived compounds are provided. The lab-scale catalytic synthesis of levulinate esters from a biomass process has been developed. This review will facilitate and inspire future research on LE synthesis from biomass

Catalytic Transfer Hydrogenation and Ethanolysis of Furfural to Ethyl Levulinate Using Sulfonated Hf- or Ni-Catalysts Prepared with Mixed Solvents

Bifunctional Lewis (L) acid (Ni- or Hf-) site–Brønsted (B) acid catalysts designed to promote transfer hydrogenation reactions were prepared via hydrothermal and solvothermal methods using safe mixed solvents and sustainable precursors. By using N,N-dimethylformamide as a basis for the desired basicity, mixed solvents could be identified that allowed catalysts to be prepared with tunable ratios of Lewis to Brønsted acid sites (L/B). The as-prepared catalysts promoted transfer hydrogenation of furfural and ethanolysis to form ethyl levulinate (EL) using ethanol as a solvent and hydrogen donor source. Among the catalysts, sulfonated Hf-catalysts prepared with a cyclopentanone/formic acid mixed solvent (Hf-CPN/FA) with an L/B ratio of 6.4 gave 95% furfural conversion with 51.9% yield of EL, while the sulfonated Hf catalyst prepared with a cyclopentanone/γ-valerolactone mixed solvent (Hf-CPN/GVL) with a total Lewis and Brønsted acid site amount of 85.1 μmol/g gave 100% furfuryl alcohol (FAL) conversion with 72.5% yield of EL. Brønsted acid sites promoted reversible acetalization of furfural with ethanol into 2-furaldehyde diethyl acetal, while Lewis acid sites promoted furfural transfer hydrogenation into FAL and EL and further conversion into γ-valerolactone. The methods developed in this work eliminate dipolar aprotic solvents and harsh acids used in catalyst synthesis and allow sustainable production of EL from biomass-related chemicals

Mechanism of Glucose Conversion into 5‑Ethoxymethylfurfural in Ethanol with Hydrogen Sulfate Ionic Liquid Additives and a Lewis Acid Catalyst

Hydrogen sulfate ionic liquid additives with aluminum chloride catalyst in ethanol were found to promote efficient (30 min) one-pot, one-step transformation of glucose into 5-ethoxymethylfurfural (5-EMF) in 37% yields. Spectroscopic measurements (FT-IR, ¹H NMR) showed that ionic liquids form multiple hydrogen bonds with glucose and promote its ring opening through ionic liquid–AlCl₃ complexes to enable formation of 5-EMF via 5-hydroxymethylfurfural (5-HMF). Reactions performed in dimethyl sulfoxide using (protic, aprotic) ionic liquid additives with and without AlCl₃ catalyst showed that both the ionic liquid and AlCl₃ were required for efficient transformation of glucose into 5-EMF. The proposed reaction mechanism for 5-EMF synthesis in the ethanol–1-butyl-3-methylimidazolium hydrogen sulfate–AlCl₃ reaction system consists of ring opening of glucose to form the 1,2-enediol and dehydration to form 5-HMF that is followed by etherification to the 5-EMF product. The reaction system is effective for glucose transformation and has application to biomass-related compounds

Solvent Polarity of Cyclic Ketone (Cyclopentanone, Cyclohexanone): Alcohol (Methanol, Ethanol) Renewable Mixed-Solvent Systems for Applications in Pharmaceutical and Chemical Processing

Kamlet–Taft (KT) parameters were measured for four nonaqueous hydrogen bond donor (HBD)–hydrogen bond acceptor (HBA) solvent-pair mixtures: methanol–cyclopentanone, methanol–cyclohexanone, ethanol–cyclopentanone, and ethanol–cyclohexanone to define their solvent polarity as a function of composition. KT mixed-solvent polarities differed greatly from molar average property values. The preferential solvation (PS) model was used to correlate solvent polarity and showed that local compositions of 1:1 (HBD–HBA) complex molecules were highly asymmetric. Trends of KT parameters of both cyclohexanone and cyclopentanone mixtures were similar, although the specific hydrogen bonding interactions of HBD–HBA complex molecules in cyclohexanone mixtures were stronger than those of cyclopentanone mixtures according to density functional theory calculations, infrared spectroscopy, and solution macroscopic properties. Application of the PS model to pharmaceuticals showed that the solvent-pair mixtures have wide-working composition ranges (∼0 < <i>x</i>_HBA < ∼ 1) for aspirin, ibuprofen, niflumic acid, <i>p</i>-amino-benzoic, <i>p</i>-hydroxy-benzoic and salicyclic acid, limited composition ranges (Δ<i>x</i>_HBA ≈ 0.7) for benzoic acid and temazepam, and narrow composition ranges (Δ<i>x</i>_HBA ≈ 0.3) for others. By comparing mixed-solvent polarity with polarity of solvents being used for material, petroleum, and biomass processing, it can be concluded that cyclic ketone–alcohol mixtures have many applications

Green and Efficient Al-Doped LaFe_<i>x</i>Al_1–<i>x</i>O₃ Perovskite Oxide for Enhanced Phosphate Adsorption with Creation of Oxygen Vacancies

La-based metal oxide materials are environmentally friendly and show promise for phosphate adsorption. A series of Al-doped perovskite oxides, such as LaFexAl1–xO3, were prepared using a facile citric acid-assisted sol–gel method. The characterization results demonstrated that with optimized Al doping, there was a significant increase in the specific surface area and increased defect content of perovskite oxide LaFexAl1–xO3. Adsorption experiments showed that the performance of phosphate removal by LaFexAl1–xO3 was largely enhanced due to the improved adsorption capacity, which is maximum eight times higher compared with control perovskites prepared under neutral conditions. The mass transfer rate for adsorption was considerably boosted with phosphate removal within the initial 15 min. Spectroscopy analysis and density functional theory calculation results showed that the process of phosphate removal by the Al-doped perovskite oxides LaFexAl1–xO3 involved electrostatic interactions, an inner-sphere complex, and surface oxygen vacancies, among which the creation of oxygen vacancies caused by the Al doping was the predominant mechanism for reducing the bonding barrier during adsorption and generating adsorption sites. The results enable the development of a green and efficient perovskite adsorbent with a La-based perovskite material for phosphorus removal

Table_1_Systematic analysis between inflammation-related index and sex hormones in American adults: cross-sectional research based NHANES 2013-2016.docx

BackgroundA series of novel inflammation-related indexes has been confirmed to be efficient indicators of human immune and inflammatory status, with great potential as predictors for a variety of diseases. However, the association between inflammation-related indexes and sex hormones in the general population remained uncertain.MethodsWe incorporated data from the NHANES 2013-2016 survey of American adults. On the basis of distribution and comparison analysis, we chose to undertake separate analyses of men and women (including premenopausal and postmenopausal groups). Multivariable weighted linear regression models, eXtreme Gradient Boosting (XGBoost) models, generalized linear analysis, stratified models, logistic regression models and sensitivity analysis were utilized to assess the relationships between inflammation-related indexes and sex hormones.ResultsTotal 9372 participants out of 20146 were fitted into our research. We conducted separate gender analysis due to different distribution. Multivariable weighted linear regression indicated every component of the inflammation-related index was negatively correlated with at least one component of the male hormone indexes. However, SII, NLR, PPN, and NC were associated positively with female estradiol. XGBoost identify SII, PLR and NLR were the critical indexes on sex hormones. Inflammation-related indexes was associated with Testosterone deficiency in male and postmenstrual group and associated with Excessive Estradiol in premenstrual group. Finally, the subgroup analysis revealed that the association between sex hormones and inflammatory indicators was prominent in American adults over the age of 60 or those with BMI (>28 kg/m2).ConclusionIn all, inflammation-related indexes act as independent risks associated with sex hormone alterations and metabolic disorder in both genders. Using multiple models, we revealed the relative importance of inflammation-related indexes. Subgroup analysis also identified the high-risk population. More prospective and experimental research should be conducted to validate the results.</p