Luffa as a lignocellulosic material for fabrication of a new and green catalyst in promoting of coumarin and bis(indolyl)methane derivatives

Abstract

For the first time, chemical modification of raw Luffa with hydrogen sulfate moieties was investigated. For this purpose ammonium hydrogen sulfate moieties were immobilized on the surface of Luffa. This chemical modification performed by reaction of 3-aminopropyltriethoxy silane with raw Luffa and sulfonation of amine groups using sulfuric acid. The morphology of catalyst was investigated by Fourier transform spectroscopy, X-ray diffraction, thermogravimetric analysis, field emission scanning electron microscope, elemental-mapping, and energy dispersive X-Ray spectroscopy techniques. The catalytic performance of the synthesized catalyst was examined in the synthesis of coumarin and bis(indolyl)methane derivatives. Our method introduced a green protocol in using of a plant for the preparation of catalyst and one-pot solventless media for the synthesis of coumarins and bis(indolyl)methanes. Some of the advantages of our method are high yields of products, short reaction times, recyclability of catalyst, easy workup, and separation of catalyst and products.

Keywords

• lignocellulose
• luffa
• coumarin
• bis(indolyl)methane
• heterogeneous catalyst