A New Sulfonic Acid-Functionalized Organic Polymer Catalyst for the Synthesis of Biomass-Derived Alkyl Levulinates

Production of levulinic acid and alkyl levulinates: a process insight

“…[69][70][71] Mineral acids, such as H2SO4, H3PO4, HCl, and p-toluene sulphonic acid (PTSA), 72 were strongly employed in the esterification for their high yields (>95 %) 73 , fast reaction rates, and low cost, but their downstream drawbacks made it mandatory their replacement, even though there were some efforts to develop acid more sustainable as the bio-glycerol derived carbon sulfonic-acid. 74 Up to now, various heterogeneous catalysts, such as zeolites, 75-77 heteropolyacids, 78,79 acid ion exchange resins, 71,80,81 nanostructured solid acid, 82 sulfonic acid-functionalized organic polymer, 83 silica based, [84][85][86] metal oxide, zirconia based, 87 nano-material catalysts [88][89][90][91] , ionic liquids 92 and biocatalysts [93][94][95] have been efficiently used to produce alkyl levulinates from LA (Table 3). Zeolites are widely used as solid acid catalysts and ionexchangers in several processes thanks to the possibility of finetuning their properties.…”

Catalytic Synthesis of Energy‐rich Fuel Additive Levulinate Esters from Levulinic Acid using Modified Ultra‐stable Zeolite Y

“…The bands in the range 400–500 cm −1 represent the Si−O−Si vibrations, from 600–900 cm −1 attributed to symmetric and from 900–1250 cm −1 asymmetric stretching of Si−O−T. The peak at 1056.94 cm −1 confirmed the presence of sulfonic group, [71] due to S=O symmetric stretching shown in Figure 5.…”

“…[70] The broadband in the region 3100-3700 cm À 1 attributes to water and SiÀ OH bridging, i. e. strong Bronsted acid sites. The bands in the range 400-500 cm À 1 represent the SiÀ OÀ Si vibrations, from 600-900 cm À 1 attributed to symmetric and from 900-1250 cm À 1 asymmetric stretching of SiÀ OÀ T. The peak at 1056.94 cm À 1 confirmed the presence of sulfonic group, [71] due to S=O symmetric stretching shown in Figure 5.…”

A box-in-box supramolecular assembly for the highly selective recognition of natural, epigenetically and chemically modified cytosines in water

“…To further confirm the formation of the supramolecular assembly, the infrared spectra of SC4H, 1 ·(PF 6 ) 4 and 1 4+ ·SC4 4− were compared (Fig. S4†), which showed that the intensities of 1038 and 1176 cm −1 in 1 4+ ·SC4 4− , due to the stretching vibration of S–O and SO in the SO 3 H group, 23 respectively, were significantly decreased, while the intensities of 1598 and 1634 cm −1 , typical of the NH 2 group, were kept unchanged, suggesting that the SO 3 H group was deprotonated, while there is no proton transfer to the NH 2 group. The formation of the supramolecular assembly was also confirmed by theoretical calculations of the interaction energy 24 (−362.09 kcal mol −1 ) and molecular electrostatic potential (MEP) surface (SI-5 and Fig.…”