RHA / TiO 2纳米复合材料的制备和表征:引入有效且可重复使用的催化剂,用于化学选择性的三甲基甲硅烷基保护和醇和酚的脱保护
摘要:
在这项工作中,稻壳灰(RHA)作为无定形二氧化硅的天然来源,被用作合成RHA / TiO 2纳米复合材料的锐钛矿相二氧化钛纳米粒子的载体。该纳米复合材料用作各种醇和酚的化学选择性三甲基甲硅烷基化和所得三甲基甲硅烷基醚的脱保护的有效催化剂。该程序在非常短的反应时间内以优异的产率获得了产物。同样,该催化剂可以重复使用至少六次,而不会损失其催化活性。
eco-friendly protocol for the chemoselective protection of benzylic and primary and less hindered secondary aliphatic alcohols and phenols as trimethylsilyl ethers and different types of amines as N-tert-butylcarbamates is developed using rice husk (RiH) as the catalyst. This reagent is also able to catalyze the acetylation of alcohols, phenols, thiols and amines with acetic anhydride. Easy work-up, relatively
Preparation and characterization of a RHA/TiO<sub>2</sub>nanocomposite: introduction of an efficient and reusable catalyst for chemoselective trimethylsilyl protection and deprotection of alcohols and phenols
nanoparticles leading to the RHA/TiO2 nanocomposite. This nanocomposite was used as an efficientcatalyst for the chemoselective trimethylsilylation of various alcohols and phenols and deprotection of the obtained trimethylsilyl ethers. The procedure gave the products in excellent yields in very short reaction times. Also this catalyst can be reused at least six times without loss of its catalytic activity.
在这项工作中,稻壳灰(RHA)作为无定形二氧化硅的天然来源,被用作合成RHA / TiO 2纳米复合材料的锐钛矿相二氧化钛纳米粒子的载体。该纳米复合材料用作各种醇和酚的化学选择性三甲基甲硅烷基化和所得三甲基甲硅烷基醚的脱保护的有效催化剂。该程序在非常短的反应时间内以优异的产率获得了产物。同样,该催化剂可以重复使用至少六次,而不会损失其催化活性。
Rice Husk Ash: A New, Cheap, Efficient, and Reusable Reagent for the Protection of Alcohols, Phenols, Amines, and Thiols
Abstract A mild, efficient, and eco-friendly protocol for the protection of alcohols and phenols as trimethylsilyl ethers has been developed using rice husk ash as a reagent. This reagent is also able to catalyze the acetylation of alcohols, phenols, thiols, and amines with acetic anhydride. All reactions were performed under mild conditions in good to high yields. [Supplementary materials are available
accurately determine isomeric cresols due to their incomplete chromatographic separation on commercially available chromatographic columns and their nearly identical massspectra. METHODS Silylation of isomeric cresols was carried out by treatment with N-methyl-N-(trimethylsilyl)trifluoroacetamide. The formed trimethyl(tolyloxy)silanes were analyzed by gas chromatography/mass spectrometry (GC/MS).
RATIONALE甲酚在许多国家被列为优先控制的污染物,但由于在市场上可买到的色谱柱上色谱分离不完全且质谱几乎相同,因此很难准确测定异构甲酚。方法用N-甲基-N-(三甲基甲硅烷基)三氟乙酰胺处理甲酚的甲硅烷基化反应。通过气相色谱/质谱(GC / MS)分析形成的三甲基(甲苯甲氧基)硅烷。使用密度泛函理论(DFT)方法在B3LYP / 6-311 + G(2d,p)级别上使用高斯03程序进行了理论计算。结果三种异构甲酚和六个异构二甲苯酚的衍生物在HP-5MS毛细管色谱柱上仅用10分钟的气相色谱就已完全分离。此外,由于其在电子电离(EI)-MS中在m / z 91处具有特征性的碱性峰离子,因此可以非常轻松地将邻甲酚与异构体区分开。DFT计算结果表明,m / z 91处大量碎片离子的形成归因于易解离途径,该途径涉及三甲基(邻甲苯基氧基)硅烷的EI-MS中相邻的苯基甲基氢原子的移动。结论甲硅烷基化
Succinimide-<i>N</i>-Sulfonic Acid: A Mild, Efficient, and Reusable Catalyst for the Chemoselective Trimethylsilylation of Alcohols and Phenols