ARTICLE | doi:10.20944/preprints202206.0055.v1
Subject: Chemistry And Materials Science, Organic Chemistry Keywords: Sulfonated silica catalyst (SiO2-SO3H); methyl salicylate; green chemistry; methylating agent; deacetylation (acyl nucleophilic substitution); solid acid catalyst
Online: 6 June 2022 (03:45:09 CEST)
SiO2-SO3H, with a surface area of 115 m2/g, pore volume of 0.38 cm3g-1 and 1.32 mmol H+/g, was used as a 20% w/w catalyst for the preparation of methyl salicylate (Wintergreen oil or MS) from acetylsalicylic acid (ASA). A 94% conversion was achieved in a microwave reactor during 40.0 minutes at 120 oC in MeOH. The resulting crude product was purified by flash chromatography. The catalyst could be re-used three times.
ARTICLE | doi:10.20944/preprints202201.0013.v1
Subject: Chemistry And Materials Science, Applied Chemistry Keywords: hydrophilic sulfonated silica catalyst; Aliquat 336; tetrabutylammonium tetrafluoroborate; transesterification; fatty acid methyl esters, DMSO.
Online: 4 January 2022 (15:24:55 CET)
Triglycerides of waste cooking oil reacted with methanol in refluxing toluene to yield mixtures of diglycerides, monoglycerides and fatty acid methyl esters (FAMEs) in the presence of 20% (w/w) catalyst/oil using the hydrophilic sulfonated silica (SiO2-SO3H) catalyst alone or with the addition of 10% (w/w) co-catalyst/oil [(Bun4N)](BF4) or Aliquat 336]. The addition of the ammonium salts to the catalyst lead to a decrease in the amounts of diglycerides in the products, but the concentrations of monoglycerides increased. Mixtures of [(Bun4N)](BF4)/catalyst were superior to catalyst alone or Aliquat 336/catalyst for promoting the production of mixtures with high concentrations of FAMEs. The same experiments were repeated using DMSO as the solvent. The use of the more polar solvent resulted in excellent conversion of the triglycerides to FAME esters with all three-catalyst media. A simplified mechanism is presented to account for the experimental results.