The catalytic performance of sulphonated cross-linked polystyrene beads in the formation of isobornyl acetate

Ketalization of epoxidized methyl oleate using acidic resins

“…These characteristics indicate that the resins have active‐acidic sites of the same nature and relative amount. Therefore, any observed difference in their activity must be a consequence of diffusional and accessibility of those acidic sites, as has been reported . On the other hand the volume‐swelling ratio of the resins in acetone increased inversely proportional to the percentage of divinylbenzene, i.e.…”

“…The glycol is formed by hydroxylation of the epoxide in the presence of residual water . According to Dijs et al an important amount of water was retained in Dowex 50WX8 and Amberlyst 15 resins (25.3 and 12.2 weight percent of water, respectively) even though these resins were dried under reduced pressure . Even a low amount of water is enough to produce the glycols because water is released again when they react with acetone.…”

Copper supported on acid-activated vermiculite as an efficient and recyclable catalyst for the Biginelli reaction: a green approach

“…The acid sites of the materials were measured by titration using standardized NaOH solution (Table 1), from the experimental data is evident that acid activation with HCl and fixation of copper complex increased the acidity of the materials and therefore enhanced the catalytic activity of AAVrm-Cu2 in the preparation of dihydropyrimidinones compounds. In comparison to materials reported in the literature, AAVrm-Cu2 shows higher acidity than raw vermiculite, vermiculite activated with sulfuric acid and vermiculite modified with sulfonic groups (Moraes et al, 2018) but the acidity is lower than in some ionic exchange resins with superficial sulfonic groups (Dijs et al, 2003) and lower than bentonite polystyrene nanocomposites functionalized with sulfonic groups (Kalbasi et al, 2012). According to the XRF analysis (Table 2), Vrm had a significant amount of Mg, Al, Fe which was expected due to the iron and magnesium aluminosilicate nature of vermiculite (Li et al, 2016), the chemical composition of Vrm is similar to those of other vermiculites previously reported (Chmielarz et al, 2010;Campos et al, 2009) additionally it presented TiO 2 , K 2 O, CaO, MnO and Cr 2 O 3 as secondary components (Table 2).…”

“…Then, the FTIR spectra of the samples were recorded in FT-IR spectrometer with ATR accessory. Acidity of the materials was determined using a reported method (Moraes et al, 2018;Dijs et al, 2003) 0.500g of material were added to an aqueous 0.10 M KCl solution (50 mL) followed by gently stirring for 20 minutes. The mixture was titrated with an aqueous 0.20 M KOH solution in the presence of 3 drops of phenolphthalein indicator (standardized with potassium hydrogen phthalate).…”

Upgrading the Glycerol from Biodiesel Production as a Source of Energy Carriers and Chemicals—A Technological Review for Three Chemical Pathways

“…An ionic exchange resin is an insoluble polymeric matrix, ordinarily consisting of polystyrene-divinylbenzene copolymers, and adsorbed labile ions which can be exchanged with others in the surrounding medium [56,57]. Ion exchange resins can also have a matrix of sulfonated cross-linked polystyrene [52,58]. Depending on the cross-linkage, which is defined as the percentage of divinylbenzene in the resin, those resins are defined as gel-type or macro-reticular type if cross-linkage is below or higher than 12%, respectively.…”