间歇式水热合成制备丝光沸石膜及其异丙醇脱水应用

采用市售廉价大孔α-Al₂O₃管作为基质材料,通过热浸渍法在管外表面涂敷晶种,随后在无模板剂体系下,利用新型的间歇式水热合成法制备丝光沸石膜。对比了传统加热和间歇式加热对丝光沸石膜形貌、结构及渗透蒸发异丙醇脱水分离性能的差异。考察了合成液中Na₂O/SiO₂、SiO₂/Al₂O₃和NaF/SiO₂物质的量之比在间歇式水热合成下对丝光沸石膜的影响。研究结果表明,当合成液中Na₂O/SiO₂、SiO₂/Al₂O₃和NaF/SiO₂物质的量之比分别为0.24、16.7和0.25时,制备的丝光沸石膜渗透蒸发异丙醇脱水分离性能最佳,在75℃下,对异丙醇/水(9:1,w/w)的渗透通量达5.60 kg·m^-2·h^-1,水对异丙醇的分离因数大于10 00...     

A variable temperature infrared spectroscopy study of NaA zeolite dehydration

Variable temperature diffuse reflectance infrared spectroscopy is used to monitor the dehydration of sodium Linde type A zeolite (NaA). Between ambient temperature and 423 K, water desorbs from NaA α-cages. At 423 K, remaining NaA water molecules are primarily confined to β-cages. Variable temperature infrared difference spectra band shape and intensity trends reflect the influence of water-Na⁺ interactions and hydrogen bonding on α-cage water desorption mechanisms. Difference spectrum variations suggest that water loss is accompanied by rearrangement of the remaining NaA water molecules to establish new interactions and minimize potential energies. Water molecules that do not interact with Na⁺ form multiple water-water hydrogen bonds and attain near bulk water configurations. These waters desorb at the lowest temperatures. Most α-cage waters are involved in Na⁺ interactions. These water molecules participate in hydrogen bonding with neighboring water molecules, but opportunities diminish with increased dehydration, resulting in systematic temperature-dependent vibrational spectrum changes.     

A facile synthesis of (±)-15-deoxy-Δ12,14-prostaglandin J2 methyl ester

A simple and facile synthesis of racemic 15-deoxy-Δ^12,14-prostaglandin J₂ methyl ester from readily available Corey lactone diol in total eleven steps was suggested. The standard methods provided a pathway to a block with an integrated w w w-chain and further to PGJ₂ methyl ester. The latter was smoothly converted to the target prostaglandin in the TsOH–CH₂Cl₂ medium when allylic alcohol moiety was transformed to exocyclic diene substituent conjugated with endocyclic enone system.