One-step synthesis of solid sulfonic acid catalyst and its application in the acetalization of glycerol: crystal structure of cis-5-hydroxy-2-phenyl-1,3-dioxane trimer

Abstract

A one-pot method was employed to immobilize sulfonic acid onto silica obtained from rice husk ash using 3-(mercaptopropyl)trimethoxysilane to form a solid catalyst denoted as RHASO3H. BET measurements of the catalyst showed the surface area to be 340 m2 g−1 with the average pore volume of 0.24 mL g−1 and the pore diameter of 2.9 nm. Acidity test of cation exchange capacity and pyridine adsorption studies revealed the presence of Brønsted acid sites on the catalyst surface. The catalyst was used in the acetalization reaction of glycerol with benzaldehyde. Under optimized conditions, the reaction showed the maximum conversion of 78 % after 8 h with 67 % selectivity towards the five membered ring isomer. Variation in the glycerol concentration had a significant effect on the reactants conversion. A single crystal X-ray study of one of the products proved the existence of a unique trimer formed by hydrogen bonding by the six-membered cis-isomer. The catalyst was several times recycled without any loss of its catalytic activity.

Preparation and Characterization of Sulfonic Acid Functionalized Silica and Its Application for the Esterification of Ethanol and Maleic Acid

“…The band at 1070 cm -1 in SG has assigned to Si-O-Si stretching, which shifted to higher wave number 1080 cm -1 in SAFS with additional shoulder. It can be attributed either to CH 3 symmetric deformation of Si-CH 3 in silane [9,10,16,18,34] or S=O stretch of SO 3 H in sulfonic acid respectively [18,34]. The more intense symmetric stretching of S=O was observed at 1384 cm -1 in SAFS and suggested the interaction between SG and 3MPTMS.…”

“…Moreover, similar to homogeneous catalyst, reactive centers of such hybrid material are highly mobile and responsible for faster reaction rate. Several researchers reported the procedure for the synthesis of solid SAFS, [9][10][11][12][13][14][15][16][17][18][19][20][21] clays [22][23][24][25], titanium dioxide [26], carbon [27] and tested their catalytic activity for various chemical reactions. In current work, surface modification and characterization of silica gel was carried out and used as catalyst in the esterification of ethanol with maleic acid, which is one of the important industrial processes.…”

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

“…Adam et al. 87 described the glycerol‐benzaldehyde ketalization reaction against silica‐supported acidic‐catalyst. Sulfonic acid was restrained in rice husk smoke, a cheap silica source.…”

Versatile Coordination Polymer Catalyst for Acid Reactions Involving Biobased Heterocyclic Chemicals

“…The reactions of Gly with aromatic aldehydes such as furfural (Fur) and benzaldehyde (Bza)-derived from lignocellulosic biomass (Fur) [104], pyrolysis of vegetable biomass (Fur and Bza) [105] or oil (Bza)-may give cyclic acetals (Scheme 1) as fuel additives [77,101,106] with antioxidant, non-toxic and renewable features [84]. Different types of acid catalysts were studied for the Bza/Gly reaction (organic acids [107], metal chlorides [108], ionic liquids [109], Keggin-tungstophosphoric acid-based [92], acid resins [77,79,110] and organic polymers [84], metal or mixed metal oxides [82,111], sulfated metal oxides [33], zeolites [19,79,82], functionalized silicas [93,102,112], mesoporous silicas or aluminosilicates [19,31,32,83,88,113] and silesquioxanes [80]), and for the Fur/Gly reaction (metal chlorides [114], resins [77,106] and organic polymer [84], metal or mixed metal oxides [78,81,99], mesoporous silicas or aluminosilicate (bulk and supported) catalysts [31,32,101,[113][114]…”