Sn(II)-Exchanged Keggin Silicotungstic Acid-Catalyzed Etherification of Glycerol and Ethylene Glycol with Alkyl Alcohols

Abstract

In this work, efficient solid acid catalysts were obtained from the stoichiometric reactions of Keggin heteropolyacids with SnSO 4 and evaluated in the etherification reactions of glycerol with tert-butyl alcohol (TBA). Among the salts synthesized, the Sn 2 SiW 12 O 40 catalyst was the most active and selective toward glyceryl ethers. High yields of mono-and diglyceryl tert-butyl ethers were achieved after 4 h of reaction at 393 K. The impacts of the main reaction parameters such as stoichiometry of the reactants, catalyst load, time, and reaction temperature were assessed. The efficiency of the Sn 2 SiW 12 O 40 catalyst was also assessed in etherification reactions of ethylene glycol with TBA, and etherification reactions of glycerol with other alcohols (i.e., n-or sec-butyl alcohol, and n-or iso-propyl alcohol). A proposal that describes the reaction pathway including the catalyst participation was also described.

How the Cobalt Position in the Keggin Anion Impacts the Activity of Tungstate Catalysts in the Furfural Acetalization with Alkyl Alcohols

“…HPAs are polyoxometalate (POMs) that emerges as a class of environmentally benign catalysts highly active in acidic or redox processes [14–17] . Nowadays, they are also demonstrated to be efficient catalysts for various organic transformations [18–20] . Due to their structural versatility, various modifications on the Keggin anion have improved their catalytic activity.…”

“…[14][15][16][17] Nowadays, they are also demonstrated to be efficient catalysts for various organic transformations. [18][19][20] Due to their structural versatility, various modifications on the Keggin anion have improved their catalytic activity. These are the main changes performed: (i) to convert HPAs to salts after exchange their protons by metal or organic cations, resulting in catalysts highly active in esterification, etherification, acetalization, and hydrolysis reactions; [21][22][23][24][25][26][27][28][29] (ii) to transform the Keggin HPAs to lacunar salts, removing one MO unit (M=W or Mo), leading to the highly active catalysts in oxidation reactions with hydrogen peroxide of olefins, alcohols, and aldehydes; [30][31][32][33][34][35] and (iii) to doping lacunar Keggin anion with a transition metal cation, resulting in efficient catalysts in oxidative transformations.…”

Direct deoxygenation of active allylic alcohols via metal-free catalysis

“…53–56 Alcohols, especially highly active allylic alcohols, under the action of Brønsted acids easily form carbocations, 57 which is also typically considered to be the intermediate step in Lewis acid-catalyzed direct deoxygenation. 58–60 Continuing our research on the transformation of alcohols using specific acidic materials, 61–64 we believe that Brønsted acids can provide protons to activate the hydroxyl group of highly active allylic alcohols in order to break the C–O bond and generate carbocations. Meanwhile, benzyl alcohol can provide the hydrogen source that acts as the reductant for a series of reactions, 65–68 except hydrosilanes, hydrazine, Hantzsch ester, HCOOH, H 3 PO 3 , and so on.…”

Glycerol Conversion to Solketal: Catalyst and Reactor Design, and Factors Affecting the Yield

“…Due to its distinct physiochemical properties, it can be converted into various useful chemical products. Different processes were previously employed for glycerol conversion like carbonylation 29, acetalization 30, etherification 31, hydrogenolysis 32, reforming 33, esterification 34, and dehydration 35. The most valuable process was converting glycerol into a fuel additive, which can enhance the properties of biofuels.…”