Benzyl benzoate and dibenzyl ether from of benzoic acid and benzyl alcohol under microwave irradiation using a SiO2–SO3H catalyst

Abstract

A sulfonated silica gel of small surface area with large pore diameters was prepared from the sodium silicate obtained from the reaction of construction sand and sodium carbonate, and sulfated with concentrated sulfuric acid. At 7%-w/w it promotes in 5 min the Fischer-Speier esterification of benzoic acid/benzyl alcohol in 93% yields, and at higher concentrations, dibenzyl ether is produced selectively and quantitatively, in solvent free reactions induced by microwave irradiation.

Dehydration of d-fructose to 5-hydroxymethyl-2-furfural in DMSO using a hydrophilic sulfonated silica catalyst in a process promoted by microwave irradiation

“…All reactions were monitored by TLC using Silica Gel 60 F 254 on aluminum. The chromatograms were visualized by UV light or by using the ethanolic vanillin developing agent 37 . The purification of the products was made by chromatographic column flash chromatography using a mixture of hexane/ethyl acetate in a 9/1 proportion as eluent 37 .…”

“…As a part of an ongoing research on the use of the SiO 2 –SO 3 H catalyst for clean synthesis 37 , we report herein the preparation of HMF from fructose with DMSO as the solvent and the hydrophilic SiO 2 –SO 3 H catalyst using microwave irradiation in processes under ambient atmosphere; MW irradiation has been widely used in the production of HMF 17 , and recently, in its oxidation to value added acid derivatives using solid catalysts containing Ru 38 or Ag 39 .…”

The preparation of benzyl esters using stoichiometric niobium (V) chloride versus niobium grafted SiO2 catalyst: A comparison study

“…The silica gel was produced as described previously [4] . To 10.00 g of this silica it was added 1.00 g of NbCl 5 , and the mixture was stirred at room temperature for 24 h, heated at 150 °C for 4 h, cooled and stored in a desiccator.…”

“…We therefore decided to compare the reactivity of NbCl 5 grafted on silica versus pure NbCl 5 and compare the results with that of the mixture NbCl 5 /Al 2 O 3 , which was shown by us to be insensible to carboxylic acids. It must be pointed out that we have already developed an hydrophilic acid-sulfonated silica catalyst, SiO 2 -SO 3 H, that is capable of producing benzyl benzoate from benzyl alcohol and benzoic acid in excellent yields (>93%) [4] , and that to the best of our knowledge, this is the first report of the direct use of the dimeric NbCl 5 in the synthesis of solid catalysts involving the niobium-silica grafting, although Basset et all employed recently the monomeric niobium pentachloride etherate for the same purpose [5] .…”

Application of Green Catalysts for the Esterification of Benzoic Acid with Different Alcohols

“…Experiments were carried out in presence of toluene and high percentage of methyl benzoate was achieved. In the study of Barbosa [19], benzyl benzoate was synthesized using H 2 SO 4 and SiO 2 -SO 3 H as catalyst. To observe the catalytic acitivity of synthetic silicas, blank experiment was performed, reagents and silica was subjected to microwave radiation, and no products were detected.…”