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Catalysts 2018, 8(1), 36; https://doi.org/10.3390/catal8010036

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

1
Chemistry Department, College of Science, Taibah University, Yanbu 30799, Saudi Arabia
2
Chemistry Department, College of Science, Suez University, Suez 41522, Egypt
3
Chemistry Department, Faculty of Science, Alexandria University, Alexandria 21321, Egypt
4
Chemistry Department, College of Science, Taibah University, Al-Medina Al-Munwarrah 30002, Saudi Arabia
*
Author to whom correspondence should be addressed.
Received: 6 December 2017 / Revised: 15 January 2018 / Accepted: 16 January 2018 / Published: 19 January 2018
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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. View Full-Text
Keywords: silica; titania; calcination process; surface modification; catalytic activity; coumarin derivatives silica; titania; calcination process; surface modification; catalytic activity; coumarin derivatives
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Radwan, N.R.E.; Hagar, M.; Afifi, T.H.; Al-wadaani, F.; Okasha, R.M. Catalytic Activity of Sulfated and Phosphated Catalysts towards the Synthesis of Substituted Coumarin. Catalysts 2018, 8, 36.

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