From Levulinic Acid to Biheterocycles: Synthesis of 1-[(5-Hydroxy-5-trifluoromethyl-3-substituted-4,5-dihydro-1H-pyrazol-1-yl)-3-(5-trifluoromethyl-1H-pyrazol-3-yl)propan-1-ones

We develop an efficient method to synthesize novel propionyl-spaced bisheterocyclic compounds. It entails cyclocondensation of 3-(5-trifluoromethyl-1H-pyrazol-3-yl)propanoyl hydrazide obtained from levulinic acid, with 1,1,1-trifluoro-4-methoxy-3-alken-2-ones proceeding regiospecifically to 1-[(5-trifluoromethyl-5-hydroxy-3-substituted-4,5-dihydro-1H-pyrazol-1-yl)-3-(5-trifluoromethyl-1H-pyrazol-3-yl)propan-1-one derivatives.     

Development of Ultrasound-Assisted Extraction to Produce Skin-Whitening and Anti-Wrinkle Substances from Safflower Seed

In this study, ultrasound-assisted extraction (UAE) was applied to extract bioactive substances with skin-whitening, anti-wrinkle, and antioxidant effects from safflower seeds, and the extraction conditions were optimized by a central composite design. The independent variables, including extraction time (5.0~55.0 min), extraction temperature (26.0~94.0 °C), and ethanol concentration (0.0~100%), were optimized to increase tyrosinase activity inhibitory (TAI), collagenase activity inhibitory (CAI), and radical scavenging activity (RSA), which are indicators of skin-whitening, anti-wrinkle, and antioxidant effects. An extraction time of 26.4 min, extraction temperature of 52.1 °C, and ethanol concentration of 50.7% were found to be optimum conditions of UAE, under which TAI, CAI, and RSA were 53.3%, 91.5%, and 27.7%, respectively. The extract produced by UAE was analyzed by LC-MS/MS, and maleic acid and levulinic acid were identified as the main substances. Therefore, UAE is evaluated as an effective process to extract skin-whitening, anti-wrinkle, and antioxidant substances from safflower seeds at lower temperatures and shorter extraction times compared to the conventional extraction methods. Overall, safflower seeds extract can be used as a material for value-added cosmetics, including maleic acid and levulinic acid, which have bioactive functions.     

Esterification of levulinic acid to n-butyl levulinate over heteropolyacid supported on acid-treated clay

Levulinic acid has been identified as a promising green, biomass-derived platform chemical. n-Butyl levulinate is used as an important intermediate having diverse applications. The present work focuses on the synthesis of n-butyl levulinate by esterification of levulinic acid with n-butanol using heteropolyacid (HPA) supported on acid-treated clay montmorillonite (K10). 20% (w/w) dodecatungestophosphoric acid (DTPA) supported on K10 was found to be the most efficient catalyst with 97% levulinic acid conversion and 100% selectivity towards n-butyl levulinate. Effects of various process parameters were studied to examine the efficacy of 20% (w/w) DTPA/K10 for optimization of the activity.     

A Catalyst and Solvent Free Route for the Synthesis of N-Substituted Pyrrolidones from Levulinic Acid

An efficient, metal-free, catalyst-free and solvent-free methodology for the reductive amination of levulinic acid with different anilines has been developed using HBpin as the reducing reagent. This protocol offers an excellent method to avoid solvents and added catalysts on the synthesis of different kinds of N-substituted pyrrolidones under metal free conditions. It is also the first report for the synthesis of different pyrrolidones by solvent-free as well as catalyst-free methods. The proposed mechanism for the formation of pyrrolidone has been supported by DFT calculations and control experiments.     

斜投影-不展开薄层色谱法对废木料液化产物乙酰丙酸的过程分析

采用多波长薄层色谱扫描法,不经过传统的薄层色谱展开步骤实现混合体系的快速定量。废木料液化过程产物为混合体系,分别将不同液化反应时间点所取样品点样于硅胶板上。仅对液化过程终点的样本点进行一次展开,分离斜投影建模所需的反射光谱,切割出目标产物(乙酰丙酸)和背景光谱,构造斜投影算子;对其他液化过程中的样品点不展开,采集混合光谱,经斜投影算法分离出其中的目标产物纯光谱,从而实现定量。将该方法的定量结果与高效液相色谱法的定量结果对比,得到两种方法测定乙酰丙酸的相对误差小于3.27%,表明两种方法具有良好的一致性。     

Kinetics of esterification of the levulinic acid with n-hexanol,n-octanol,and n-decanol in the presence of dodecatungstophosphoric acid as a catalyst

Levulinic acid was esterified with n-hexanol, n-octanol, and n-decanol at 393–413 K and at molar ratios of between 3:1 and 10:1 (alcohol: acid) in the presence of the dodecatungstophosphoric acid (H₃PW₁₂O₄₀) as catalyst (0.1 wt%) to study the reaction kinetics. The results of such study are the precise form of kinetic equation, which is indispensable in design and optimization of industrial-scale chemical reactors. The authors stated that reactions were of second order and that the activation energy (E) decreased from 66 to 53 kJ/mol in the following alcohol sequence: n-hexanol > n-octanol > n-decanol.     

炭载钌催化剂的微波制备及其水相乙酰丙酸加氢性能

生物质衍生物乙酰丙酸是生物质转化过程中重要的平台分子,对其进行催化加氢可以得到高附加值的产物,是连接生物质转化和石油化工的重要途径。本实验研究了无溶剂微波辅助热解法绿色制备负载型钌基催化剂,以Ru₃（CO）₁₂为金属前体,碳纳米管、椰壳活性炭和活性氧化铝为催化剂载体,该制备方法简单易操作,环保高效低能耗,不使用溶剂,避免了杂质的引入和对催化剂的污染,是一种新型负载型贵金属催化剂的制备方法。同样采取传统浸渍法制备Ru/γ-Al₂O₃-IM。在乙酰丙酸水相催化加氢反应中的催化活性顺序为Ru/AC > Ru/CNT ≈ Ru/FCNT > Ru/γ-Al₂O₃-MW ≈ Ru/γ-Al₂O₃-IM。比较不同反应溶液水、甲醇、乙醇、苯甲醚、环己烷和丙酮等对于乙酰丙酸催化加氢反应的影响,并通过考察反应温度、反应压力和反应物初始浓度等因素对加氢反应的影响,确定最佳实验条件为：反应温度为90℃,反应压力2.0 MPa,适宜反应物浓度为0.10 g/mL,产品GVL收率大于99%。     

The role of protic solvent in asymmetric hydrogenation of methyl levulinate in the presence of a ruthenium-containing catalyst

A comparative study of asymmetric hydrogenation and deuteration of methyl levulinate catalyzed by the Ru^II—(S)-BINAP—HCl system (BINAP is 2,2′-bis(diphenylphosphino)-1,1′-binaphthyl) in MeOH and MeOD was carried out. The results obtained suggest an important role of the protic solvent in the formation of catalytically active ruthenium complexes. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 531–533, March, 2007.     

Catalytic Conversion of Glucose into Levulinic Acid Using 2-Phenyl-2-Imidazoline Based Ionic Liquid Catalyst

Levulinic acid (LA) is an industrially important product that can be catalytically valorized into important value-added chemicals. In this study, hydrothermal conversion of glucose into levulinic acid was attempted using Brønsted acidic ionic liquid catalyst synthesized using 2-phenyl-2-imidazoline, and 2-phenyl-2-imidazoline-based ionic liquid catalyst used in this study was synthesized in the laboratory using different anions (NO₃, H₂PO₄, and Cl) and characterized using ¹H NMR, TGA, and FT-IR spectroscopic techniques. The activity trend of the Brønsted acidic ionic liquid catalysts synthesized in the laboratory was found in the following order: [C₄SO₃HPhim][Cl] > [C₄SO₃HPhim][NO₃] > [C₄SO₃HPhim][H₂PO₄]. A maximum 63% yield of the levulinic acid was obtained with 98% glucose conversion at 180 °C and 3 h reaction time using [C₄SO₃HPhim][Cl] ionic liquid catalyst. The effect of different reaction conditions such as reaction time, temperature, ionic liquid catalyst structures, catalyst amount, and solvents on the LA yield were investigated. Reusability of [C₄SO₃HPhim][Cl] catalyst up to four cycles was observed. This study demonstrates the potential of the 2-phenyl-2-imidazoline-based ionic liquid for the conversion of glucose into the important platform chemical levulinic acid.     

Enantioselective hydrogenation of levulinic acid esters in the presence of the Ru<Superscript>II</Superscript>-BINAP-HCl catalytic system

The rate of hydrogenation of γ-ketoesters MeCOCH₂CH₂COOR (R = Et, Prⁱ, Bu^t) in the presence of the chiral Ru^II—BINAP catalyst (BINAP is 2,2′-bis(diphenylphosphino)-1,1′-binaphthyl) greatly increases upon the addition of 5–10 equivalents of HCl with respect to ruthenium. In the hydrogenation of ethyl levulinate, the optically active γ-hydroxy ester initially formed would cyclize by ∼95% to give γ-valerolactone with optical purity of 98–99% ee. When the Ru(COD)(MA)₂—BINAP—HCl catalytic system is used (COD is 1,5-cyclooctadiene, MA is 2-methylallyl), complete conversion of the ketoester (R = Et) in EtOH is attained in 5 h at 60 °C under an H₂ pressure of 60–70 atm. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2301–2304, October, 2005.