Sulfonic Acid Functionalized Ordered Mesoporous Silica and their Application as Highly Efficient and Selective Heterogeneous Catalysts in the Formation of 1,2‐Monoacetone‐D‐glucose

Abstract

A series of sulfonic acid functionalized ordered mesoporous silica (OMS), designated as RSO3H‐OMS (R=alkyl or aryl; OMS=MCM‐41, IITM‐56 or SBA‐15), were prepared by post‐synthesis grafting method. These catalysts, in general, exhibit strong acidic sites and, therefore, yield diacetone‐D‐glucose as main product in the D‐glucose acetonation reaction. On the other hand, the functionalized catalyst can also be tuned in such a way to generate significant amount of weak‐to‐moderate acidic sites, which are in turn responsible for the formation of 1,2‐monoacetone‐D‐glucose, hitherto not reported so far. These functionalized materials also show promise as they are water tolerant catalyst as well as exhibit varying acidic strengths, which allow greater flexibility for the desired product. In addition, the uniform mesopores with high surface area permit bulkier molecules to enter the active sites, thus the catalyst offers larger pliability in terms of yield and reusability. We report here, for the first time, RSO3H‐SBA‐15, with sizable amount of weak‐to‐moderate acidic sites, as a robust heterogeneous catalyst for the formation of the targeted molecule, 1,2‐monoacetone‐D‐glucose.

One-pot cascade conversion of xylose to furfuryl alcohol over a bifunctional Cu/SBA-15-SO3H catalyst

“…4, exhibit two relative intensive bands at 1090 and 3400 cm -1 , belonging to the asymmetric Si-O-Si and O-H vibrations, respectively. Meanwhile, the same typical silica characteristic peaks of symmetric stretching vibrations from the Si-O bonds at 800 cm -1 and bending vibrations from the Si-O-Si bonds at 466 cm -1 were observed on both the SBA-15 and SBA-15-SO3H spectra, as previously reported in the literature [30,31]. Besides, the peaks at 965 and 1620 cm -1 were associated with the Si-O-H bonds and bending vibrations from O-H bonds, respec- tively [38].…”

“…Besides, the peaks at 965 and 1620 cm -1 were associated with the Si-O-H bonds and bending vibrations from O-H bonds, respec- tively [38]. Distinctive features appearing on sulfonated SBA-15 was detected by the special bands at 1180 and 690 cm -1 , assigned to the stretching vibrations of the S=O and S-O bonds, This corroborated the availability of the -SO3H groups on the functionalized SBA-15 material, which ascertained the crucial acidity of the catalyst [30,35,38]. The peaks at 2850 and 600 cm -1 corresponding to the stretching vibrations of the C-H and C-S bonds, stemmed from the residual S-containing organosilanes (MPTMS) for the incorporation of SO3H [38,39].…”

“…The XRD pattern of SBA-15 showed a strong diffraction peak at 0.9°, reflecting the formation of the (100) facet of SBA-15. Meanwhile, two relatively small diffraction peaks were observed at 1.5° and 1.7°, corresponding to the (110) and (200) facets of SBA-15, respectively, which confirmed that the SBA-15 materials with well-ordered mesoporous structures were successfully synthesized [29,30]. Although the high-order (110) and (200) diffraction peaks on sulfonated SBA-15 and Cu/SBA-15 were hardly distinguishable, the signal of the (100) facet revealed that the mesoporous structure of SBA-15 was maintained with a slight decrease in crystallinity [31].…”

Functionalized Silicas for Metal‐Free and Metal‐Based Catalytic Applications: A Review in Perspective of Green Chemistry

“…Amine, sulfonic acid and IL FSs are employed as the solid reusable organocatalysts for the synthesis of many chemicals in the recent literature. Sulfonic acid FSs are found to be the very good catalysts for the synthesis of polyhydroquinolines, bis(indolyl)methanes, n‐butyl levulinate, chiral cyanohydrins, tetrahydrobenzo[ b ]pyrans, 5‐ethoxymethylfurfural and 1,2‐monoacetone‐D‐glucose . The acidic strength of sulfonic acid FSs is tuned by X. Feng et al.…”

“…To prepare the heterogeneous catalysts, the homogeneous catalysts/catalytic active sites are generally immobilized on the supports . Despite their inertness, catalytic supports can sometimes influence the catalytic activity/product selectivity of the immobilized active sites/homogeneous catalysts on the basis of their surface area, hydrophobicity, and porosity . As a result, finding the right support with respect to the type of catalytic active sites has become significant.…”