Synthesis of acrolein by gas‐phase dehydration of glycerol over silica supported Bronsted acidic ionic liquid catalysts

BACKGROUND: Glycerol has become readily available as a byproduct from the biodiesel industry. High functionality and relatively low price make it a potential building block to produce value‐added derivatives such as acrolein. RESULTS: Dehydration of glycerol to acrolein was performed over several silica supported Brønsted acidic ionic liquids as catalysts. All the catalysts prepared were active for the synthesis of acrolein (conversion of glycerol was observed in the range 35–90% with selectivity to acrolein in the range 29–58%). CONCLUSIONS: Catalyst prepared from triphenyl (3‐sulfopropyl) phosphonium 4‐methylbenzenesulfonate gave good activity and selectivity at 4 h reaction time. The conversion of glycerol decreased with increase in glycerol concentration. Higher temperature (325 °C) resulted in significantly lower conversion as well as selectivity to acrolein. With the use of two additional traps cooled to ? 7 °C, the selectivity to acrolein increased significantly for good catalysts. Copyright © 2010 Society of Chemical Industry     

甘油脱水制丙烯醛催化剂的研究进展

伴随着生物柴油的产量不断增大,大量副产的甘油导致了市场过剩。甘油脱水制取丙烯醛是提高生物柴油经济性的一条有效途径。本文结合近年来甘油脱水制丙烯醛的研究进展情况,分析了液相、气相以及超（亚）临界条件下该反应的特点,重点阐述了气相脱水催化剂的研究进展,讨论了催化剂的微观结构、活性组分的酸碱性和氧化还原位等对催化剂活性、选择性和寿命等的影响,分析了催化剂失活的原因。此外,还讨论了甘油脱水过程的反应机理,指出了今后甘油脱水制丙烯醛的研究方向。     

High Regioselective Diels–‐Alder Reaction of Myrcene with Acrolein Catalyzed by Zinc‐Containing Ionic Liquids

The ambient zinc‐containing ionic liquids, MX‐ZnCl₂, functioning as both Lewis acid catalyst and green solvent, are employed for a high regioselective Diels–Alder reaction of myrcene with acrolein for the first time, where MX is either 1‐butyl‐3‐methylimidazolium chloride (BmimCl), 1‐ethyl‐3‐methylimidazolium bromide (EmimBr), N‐butylpyridinium bromide (BPyBr), or N‐ethylpyridinium bromide (EtPyBr). Compared with the analogous reaction performed over a ZnCl₂ catalyst in the conventional solvent dichloromethane, higher regioselectivity of the ‘para’ cycloadduct and excellent yield were achieved at shorter reaction time in these ionic liquids with optimized molar compositions of MX and ZnCl₂. These moisture‐insensitive ionic liquids can be easily separated from reaction products after simple washing with hexane, allowing their reuse with no obvious loss in activity.     

经口给予透明质酸的生理功能及其作用机制研究进展

透明质酸（hyaluronic acid，HA）广泛存在于人体各个组织中，具有保湿、润滑等多种生理功能，并且参与到伤口愈合、炎症反应、组织修复等多个生物过程中。HA作为重要的医疗和美容材料，已被广泛应用于医药和化妆用品。2021年1月7日，国家卫生健康委员会发文，批准透明质酸钠为“新食品原料”，可应用于普通食品添加。口服作为最理想和经济、方便的给药方式，具有更高的使用依从性。本文综述了目前已发表的经口给予HA相关代表性研究成果，主要关注其在体内的吸收、分布和代谢途径，以及其对于不同组织、器官的保护功能，并结合药理、毒理研究为新型口服HA制剂的开发和应用提供科学依据，同时提高大众对于口服HA的正确认知。     

H_3PW_(12)O_(40)/Al_2O_3催化剂在甘油脱水制备丙烯醛反应中的性能评价研究

采用等体积浸渍法制备了H3PW12O40/Al2O3催化剂,在常压连续流动固定床反应器中,对催化剂的活性稳定性进行了考察,同时利用BET、SEM和XRD等对反应前后的催化剂进行了基本表征。结果显示,在反应过程中,催化剂上的积炭量呈上升趋势,尤其在催化剂活性增长期其积炭生成速率很快。较高的空速有利于减少催化剂上的积炭量。积炭可能是由丙烯醛在杂多酸催化剂上的聚合而产生的,它覆盖在催化剂表面,堵塞了孔道,从而引起了催化剂活性降低。但积炭并没有破坏催化剂的结构,催化剂仍然保持Keggin结构,仍具有催化活性。     

强酸性阳离子树脂催化丙烯醛水合反应的研究

以强酸性阳离子树脂为催化剂,考察了在间歇式和固定床中两种不同方式下的丙烯醛水合反应情况,并研究了此类树脂催化丙烯醛水合工艺条件。结果表明,D072型强酸性树脂因其酸性强,催化丙烯醛水合反应时存在着反应温度低、转化率高等特点,但产物选择性较低;在所选两种不同反应方式中,间歇式反应需时较长,且容易控制丙烯醛分子在催化剂表面的停留时间,丙烯醛的转化率及产物3-羟基丙醛的选择性最高可达到60.00%和63.01%;在连续反应中,丙烯醛转化率仅为45.57%,产物选择性为65.24%,产率低于间歇反应。连续反应中因省略了催化剂的分离过程,并可以有效地减少丙烯醛的挥发,因此更加有利于工业化生产。     

Selective conversion of allyl alcohol to oxygenates and hydrocarbons using ion exchanged zeolite Y

The reaction of allyl alcohol using zeolite Y as catalyst has been investigated and it is shown that it can be converted into a range of products, including hydrocarbons, acrolein and diallyl ether. Control of product selectivity can be achieved by careful selection and manipulation of the charge balancing cation, a series of catalysts can be prepared which, for the conversion of allyl alcohol, lead almost exclusively to the initial formation of either (a) C₂-C₆ hydrocarbons and coke (H-NaY), (b) acrolein (H-CsY), (c) propene (Li-NaY) or (d) diallyl ether (Cs-NaY). The effects of addition of H₂ and H₂O to the reactant are described and discussed with respect to the reaction mechanism and the reaction of potential intermediates (2-propanol and propene oxide) is also described. Mechanisms of formation of the major products are proposed that involve the concerted action of Brønsted acid and basic sites within the zeolite. In particular, since the addition of H₂O does not affect the product distribution, it is considered that the mechanism of hydrocarbon formation does not involve the allyl cation as an intermediate.     

丙烯醛-丙氨酸加合物制备与细胞毒性

丙烯醛是热加工食品中存在的有害物质,形成后易与氨基酸反应生成加合物,但目前对其加合物的毒性研究较少。本研究设置不同丙烯醛与丙氨酸浓度比（2∶1、1∶1、1∶2、1∶3、1∶4）,于37 ℃和50 ℃下分别水浴反应0.5、3、5、6 h,发现丙烯醛与丙氨酸浓度比1∶2在50 ℃反应5 h所获得目标加合物产率最高。通过反相硅胶柱层析进行分离纯化后,经高效液相和液相色谱-质谱联用分析,结果显示该加合物最大吸收波长为220 nm,纯度达95%以上。高分辨质谱和核磁共振鉴定结果表明,该加合物相对分子质量为183.082 3,是由一分子丙氨酸与两分子丙烯醛发生迈克尔加成反应后,经羟醛缩合形成的含氮六元环化合物。采用加合物培养人正常胃黏膜细胞（GES-1）24 h和48 h后发现,加合物半抑制浓度（half maximal inhibitory concentration,IC50）分别为3.286、0.869 mmol/L,显著降低了丙烯醛（IC50分别为0.058、0.067 mmol/L）的细胞毒性,说明丙氨酸可作为食品中丙烯醛的潜在清除剂。     

123树脂的合成、改性及在推进剂和炸药中的应用

介绍了123树脂的组成及固化机理,重点介绍了123树脂的合成、精制及改性,其中催化剂的选择不仅影响催化活性和反应速度,还能直接影响预聚物的黏度,进而影响固化产物的性质.此外,还介绍了123树脂在推进剂和炸药中的应用情况.