Sharif Digital Repository

A combination of solid acids, including Oxone®, HIO3, H 5IO6, and polystyrenesulfonic acid and sodium nitrite, in the presence of wet SiO2 were used as an effective oxidizing agents for the oxidation of dihydropyridines to their corresponding pyridine derivatives under mild and heterogeneous conditions in good to excellent yields  

4H-chromenes play a significant role in natural and pharmacological products. Despite continuous advances in the synthesis methodology of these compounds, there is still a lack of a green and efficient method. In this study, we have designed cysteic acid chemically attached to magnetic graphene oxide (MNPs·GO-CysA) as an efficient and reusable solid acid catalyst to synthesize 4H-chromene skeletons via a one-pot three components reaction of an enolizable compound, malononitrile, an aldehyde or isatin, and a mixture of water–ethanol as a green solvent. This new heterogeneous catalyst provides desired products with a good to excellent yield, short time, and mild condition. This procedure... 

Under solvent free conditions between 40-50 °C, BF3.SiO 2, a mild solid acid catalyst, is applied to regio-chemo and stereoselective Claisen-Schmidt condensation. The procedure is very simple and the products are isolated with an easy workup in good to excellent yields  

Reduction of aromatics implies that the gasoline pool would suffer both quantitatively and qualitatively. Alkylates (highly branched paraffinic hydrocarbons) are ideal substitutes because of their high octane numbers, and environmental friendly characters. Alkylates have played significant roles in US gasoline pool, while in Europe alkylates have a lesser important role. The phase out of lead and the increased capacity of FCC units for making more gasoline from heavier petroleum cuts have enhanced the validity of alkylation processes in petroleum refineries. Based on the data obtained in the laboratory using a new developed catalyst, it is predicted to behave as a successful catalyst for C4... 

A comprehensive study was carried out for the first time on the acidity of eleven different leaves. After functionalization of the leaves with –SO3H groups, the most acidic one was magnetized using nickel ferrite nanoparticles. This novel, inexpensive, green and biodegradable catalyst showed high activity in the synthesis of pyrazoline and 2-amino nicotinonitriles. Some compounds are new and have never been synthesized before and confirmed by FT-IR, 1H NMR and 13C NMR analysis. All of these compounds possess multiple biological activities. The heterogeneous magnetic catalyst (NiFe2O4-Alnus-SO3H) was characterized by various physicochemical techniques such as FT-IR spectroscopy, field... 

The deactivation of solid acid catalysts in liquid phase alkylation of isobutane with 2-butene was investigated. Since under liquid phase conditions the alkylation reaction is severely diffusion limited, effects of diffusion on the rate of reaction and deactivation pathways were considered. In the present work, an attempt has been made to implement more appropriate assumptions in order to properly model catalyst deactivation in a mixed reactor. Accordingly, spatial variation of diffusivity in the pores of the catalyst was considered as a function of time on stream. The effect of the pore mouth plugging was also investigated and it was found that this phenomenon had a pronounced effect on the... 

The catalytic activity of a mixture of ZnCl2: AlCl3 supported on silica gel was evaluated for the alkylation of phenols with benzyl alcohol, tret-butyl alcohol and styrene under microwave irradiation and solvent-free conditions. The catalyst preparation method, its characterization and reusability, were reported. The effect of the phenol to benzyl alcohol ratio and the time of reaction on the phenol conversion and distribution of products was investigated. A conversion percentage up to 97% was achieved when hydroquinone was used. A selective ortho- directed alkylation for phenol, α-naphthol and β-naphthol was observed. © Sharif University of Technology, December 2009