Synthesis and Characterization of Acidic Nano-Diatomite Catalyst and its Application in the Synthesis of ۱,۴-dihydropyridine Derivatives Via Hantzsch Reaction

A homogenous acid catalyst such as HCl, H۲SO۴ or HNO۳ covers abroad range of application such as electrophilic addition esterification, ester hydrolysis aromatic electrophilic substitution or rearrangement reaction. Despite their usefulness, these acids are highly corrosive, many of them release gasses and suppression product from the acid is often difficult that pose safety the health hazards. In addition, most of them are impossible to reuse. Due to the importance of acid catalysts, a significant effort was made to solve this problem. Supported catalyst in a different career such as diatomite, silica, bentonite investigated.diatomite, is a material of sedimentary origin. The structure of diatomite is quite complex and contains numerous fine microscopic pores, cavities, and channels, and therefore the material has a large specific surface area, high absorption capacity, and low density. Other intrinsic properties are low thermal conductivity, relatively high melting-point, chemical inertness, and small grain size. Additionally, its relatively low price and high abundance mean that the materials can be used extensively as insulating materials, conventional catalyst supports, membranes, and biocatalytic proteins and cells.[۱, ۲].When the dimensions of the diatomite become nano, the number of operating units increased. so, in a catalytic process, the more effective contact surface between the catalyst and the raw material increases and the rate of the reaction increase[۳].In this work, we have prepared a novel Acidic Nano-Diatomite Catalyst via a three-step method from Diatomite soil and after characterization of catalyst by XRD, FT-IR, and TGA we used it component to the synthesis of ۱,۴-dihydropyridine solvent-free Hantzsch reaction (Scheme ۱). The catalyst showed high catalytic activity for synthesis ۱,۴-dihydropyridine after a five-time reuse catalyst.

کلیدواژه ها:

Synthesis ، catalyst ، nano-diatomite ، ۱ ، ۴-dihydropyridine ، Hantzsch reaction