Catalytic Activity of Sulfated and Phosphated Catalysts towards the Synthesis of Substituted Coumarin

Abstract

New modified acidic catalysts were prepared from the treatment of silica, titania and silica prepared from hydrolyzed tetraethyl orthosilicate (TEOS) with sulfuric and phosphoric acid. The sulfated and phosphated silica synthesized from TEOS were calcined at 450 and 650 • C. These catalysts were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), transmission electron microscope (TEM), and scanning electron microscope (SEM). The surface areas, total pore volume, and mean pore radius of the acidic catalysts were investigated, while the pore size distribution was determined by the Barrett, Joyner and Halenda (BJH) method. The catalytic activity of the sulfated and phosphated silica and/or titania were examined with the Pechmann condensation reaction, in which different phenols reacted with ethyl acetoacetate as a neat reaction to obtain the corresponding coumarin derivatives. The results indicated that the treatment of the catalysts with sulfuric or phosphoric acid led to a decrease in the phases' crystallinity to a certain degree. The morphology and the structure of the acidified catalysts were examined and their particle size was calculated. Furthermore, the amount of the used catalysts played a vital role in controlling the formation of the products as well as their performance was manipulated by the number and nature of the active acidic sites on their surfaces. The obtained results suggested that the highest catalytic conversion of the reaction was attained at 20 wt % of the catalyst and no further increase in the product yield was detected when the amount of catalyst exceeded this value. Meanwhile the phenol molecules were a key feature in obtaining the final product.

Biodiesel Glycerin Valorization into Oxygenated Fuel Additives

“…3) showed patterns ascribable to amorphous materials like raw silica (amorphous according to the supplier). As reported in the literature [27], the broad feature around 2θ = 22.5° belongs to amorphous silica. Diffraction lines of silica phosphate are absent which seems to confirm the good dispersion of P species with the probable formation of small (nanostructured) aggregates of silica phosphates.…”

A greatly improved procedure for the synthesis of an antibiotic-drug candidate 2,4-diacetylphloroglucinol over silica sulphuric acid catalyst: multivariate optimisation and environmental assessment protocol comparison by metrics

“…S2 †) consist of similar patterns, with a broad peak in the range of 22.6 , which corroborated the non-crystalline nature of SG. 47 The decrease in this peak's intensity compared to that of SSA implies that sulphonation was successfully achieved. 48 Aerwards, FT-IR analysis was employed in order to conrm the successive functionalisation of SG to form SSA.…”

Diels–Alder Cycloaddition of Biomass-Derived 2,5-Dimethylfuran and Ethylene over Sulfated and Phosphated Metal Oxides for Renewable p-Xylene

“…As shown in Table 2, the sulfur content in the sulfated silica samples, SiS 300 and SiS 500, was remarkably low The chemical state of sulfuric acid attached to the oxide support was analyzed using FT-IR spectroscopy, and the results are presented in Figures S3 and S4 for the silica-and titania-based catalysts, respectively. In Figure S3, the infrared (IR) bands in the region from 900 to 1200 cm −1 correspond to Si-OH and Si-O-Si stretching vibrations, whereas the IR band around 800 cm −1 corresponds to the Si-O bending vibration [24][25][26]. The IR band for SiO 2 -SO 3 H appears around 1170 cm −1 , which is related to the Si-O-SO 3 H stretching vibration [26].…”

“…For a typical synthesis, 1 g of SiO 2 (or TiO 2 ) was added to 6 mL of acetone, and mixed vigorously for 15 min. 0.2 mL of H 2 SO 4 (or H 3 PO 4 ) solution mixed with 5 mL of acetone was then added to the support material solution and stirred for 4 h at 303 K. The paste was dried in the oven at 373 K for 24 h. After drying, the obtained solid powder was washed several times with a deionized water to remove the excess acid molecules, which do not adsorb on the surface, and was dried at 373 K overnight [24]. Finally, the powder was calcined in flowing air at 573 K (or 773 K) for 6 h. The catalysts' names were differentiated by the type of support and calcination temperature (SiP 300, SiP 500, SiS 300, SiS 500, TiP 300, TiP 500, TiS 300, TiP 500).…”