4443-51-0Relevant articles and documents
Monoterpenes etherification reactions with alkyl alcohols over cesium partially exchanged Keggin heteropoly salts: effects of catalyst composition
da Silva, Márcio José,Lopes, Neide Paloma Goncalves,Ferreira, Sukarno Olavo,da Silva, Rene Chagas,Natalino, Ricardo,Chaves, Diego Morais,Texeira, Milena Galdino
, p. 153 - 168 (2020/07/21)
In this work, cesium partially exchanged Keggin heteropolyacid (HPA) salts were prepared, characterized, and evaluated as solid catalysts in monoterpenes etherification reactions with alkyl alcohols. A comparison of the activity of soluble HPAs and their insoluble cesium salts showed that among three different Keggin anions the phosphotungstate was the most efficient catalyst. Assessments on the effects of the level of the protons exchange by cesium cations demonstrated that Cs2.5H0.5PW12O40 solid salt was the most active and selective phosphotungstate catalyst, converting β-pinene to α-terpinyl methyl ether. The influences of the main reaction parameters such as reaction temperature, time, catalyst load, substrate nature (i.e., alcohols and monoterpenes) were investigated. We have demonstrated that the simultaneous presence of the cesium ions and protons in the catalyst plays an essential role, being the 2.5–0.5 the optimum molar ratio. The Cs2.5H0.5PW12O40 salt was efficiently recovered and reused without loss of catalytic activity. Graphic abstract: [Figure not available: see fulltext.]
Synthesis of phenolic antioxidants with isobornyl and tert-butyl fragments
Fedorova,Chukicheva,Shumova,Kutchin
, p. 1103 - 1110 (2013/08/23)
Hybrid antioxidants, phenols with a terpene and tert-butyl substituents, were synthesized by the alkylation of 2-tert-butyl-4-methylphenol with camphene and 2-isobornylphenol with tert-butyl chloride in the presence of acidic heterogeneous catalysts, montmorillonite KSF and FIBAN K-1. Antioxidant activity of the synthesized terpenophenols was evaluated using spectrophotometry.
Trimethylsilyldiazomethane - A mild and efficient reagent for the methylation of carboxylic acids and alcohols in natural products
Presser, Armin,Huefner, Antje
, p. 1015 - 1022 (2007/10/03)
Esterification of various naturally occurring carboxylic acids with trimethylsilyldiazo-methane proceeds nearly quantitatively under very mild conditions. Furthermore, highly sterically hindered alcohols can be converted directly to the corresponding methyl ethers. Improved methods for the preparation and quantification of this reagent are described. Springer-Verlag 2004.
