Rapid and Efficient N-tert-butoxy carbonylation of Amines Catalyzed by Sulfated Tin Oxide Under Solvent-free Condition

A straightforward, rapid, and efficient protocol for the N-tert-butoxy carbonyl (N-Boc) protection of amines (aromatic, aliphatic) using sulfated tin oxide catalyst is illustrated. N-Boc protection of various amines was carried out with (Boc)2O using sulfated tin oxide as a catalyst at room temperature under solvent-free conditions. Rapid reaction times, ease of handling, cleaner reactions, easy work-up, reusable catalyst, and excellent isolated yields are the striking features of this methodology which can be considered to be one of the better methods for the protection of amines and alcohols. DOI: http://dx.doi.org/10.17807/orbital.v10i7.115

Utilization of carbon dioxide in oxidative dehydrogenation reactions

1315-1324Utilization of CO2 as a feedstock for synthesis of chemicals is an alternate and most promising option for CO2 abatement. In the present study, CO2 has been utilized as a soft oxidant for oxidative dehydrogenation of ethylbenzene and <i style="mso-bidi-font-style: normal">n-butane to the corresponding olefins. For this, TiO2−ZrO2 (TZ) mixed oxide-supported V2O5, CeO2 and V2O5–CeO2 catalysts has been synthesized, characterized and evaluated for the oxidative dehydrogenation reactions. The physicochemical characterization has been achieved by various techniques such as, powder X-ray diffraction, CO2 and NH3 temperature-preprogrammed desorption, temperature-preprogrammed reduction, X-ray photoelectron spectroscopy and BET surface area methods. XRD analysis of the samples calcined at 550 °C indicates that the impregnated active components are in a highly dispersed state on the support. XP spectra shows the existence of vanadium and cerium in V4+ and Ce4+/Ce3+ oxidation states, respectively. Among the various catalysts investigated, V2O5−CeO2/TiO2−ZrO2 exhibits a high conversion and product selectivity for the oxidative dehydrogenation of ethyl benzene. On the other hand, a high conversion and selectivity in the oxidative dehydrogenation of <i style="mso-bidi-font-style: normal">n-butane is noted over V2O5/SnO2−ZrO2 mixed oxide catalyst. The combined acid–base and redox properties of the catalysts play a major role in these reactions. In particular, the characterization studies reveal that mixed oxides show a high specific surface area, superior acid-base properties and better redox characteristics. All these properties enhance the catalytic performance of mixed oxide catalysts

Design of novel ceria-based nano-oxides for CO oxidation and other catalytic applications

186-195Carbon monoxide oxidation over various ceria-based solid solutions has been reviewed. The advantageous incorporation of various dopants in the ceria lattice (CexM1–xO2; M = Zr and Hf, and CexM1–xO2-d; M = La and Pr) to improve oxygen storage capacity and CO oxidation activity have been addressed. Nanosized doped ceria solid solutions are synthesized by a newly developed coprecipitation method from ultrahigh dilute aqueous solutions. To establish the thermal stability, the synthesized materials have been calcined at 773 and 1073 K and thoroughly characterized by various state-of-the-art techniques. The structural features have been investigated by X–ray diffraction, transmission electron microscopy, Raman spectroscopy, UV–visible diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy and BET surface area. X-ray differaction and Raman Spectroscopic studies establish the formation of solid solutions and the TEM analysis specifies the nanosized nature of the mixed oxides. Further, the XPS and UV–vis DRS studies establish the existence of cerium in both 3+ and 4+ oxidation states and the presence of oxygen vacancies, respectively. Among various combinations, the ceria-hafnia solid solution exhibits the best oxygen storage capacity and excellent CO oxidation activity. As revealed by this model study, there is ample scope to design better materials for CO oxidation and related pollution abatement applications

Selective oxidation of p-methoxytoluene to p-methoxybenzaldehyde over supported vanadium oxide catalysts

256-258<span style="font-size:11.0pt;line-height:115%; font-family:" calibri","sans-serif";mso-ascii-theme-font:minor-latin;mso-fareast-font-family:="" "dejavu="" sans";mso-hansi-theme-font:minor-latin;mso-bidi-font-family:mangal;="" mso-bidi-theme-font:minor-bidi;color:#00000a;mso-ansi-language:en-us;="" mso-fareast-language:en-us;mso-bidi-language:ar-sa"="">Partial oxidation of p-methoxytoluene to p-methoxybenzaldehyde was studied in vapour phase at normal atmospheric pressure over titania, alumina, titania-alumina, titania-silica, titania-zirconia, titania-silica-zirconia, silica-zirconia, magnesia, calcia-magnesia supported vanadia catalysts. Vanadium oxide on basic supports, MgO and CaO-MgO, shows better selectivity towards p-methoxybenzaldehyde with considerable conversion of p-methoxytoluene at 673 K temperature. However, other acidic single and mixed oxide supported vanadium oxide catalysts exhibit poor selectivity at high conversion.</span