Solvent-Free Biginelli Reactions Catalyzed by Hierarchical Zeolite Utilizing Ball Mill Technique: Green Sustainable Process

Abstract

A sustainable green one pot procedure for the synthesis of dihydropyrimidinones (DHPMs) derivatives by a three-component reaction of β-ketoester derivatives, aldehyde and urea or thiourea over the alkali-treated H-ZSM-5 zeolite under ball-milling has been developed. The product was isolated by simple washing of the crude reaction residue with ethyl acetate followed by evaporation of solvent. The hierachical zeolite catalyst (MFI27_6) showed high yield (86-96%) of dihydropyrimidinones (DHPMs), in very short time (10-30 min). The catalyst is recycled for subsequent reactions in four runs without appreciable loss of activity and high yields of products provide efficient protocol for Biginelli reactions.

A route to selectively increase the microporous structure of zeolite and its optimization in the ethanol to butadiene reaction

“…d Hierarchy factor = (V micro /V total ) × (S meso / S BET ). 31 e The relative crystallinity was calculated from the peak area at 2θ = 22.4°and the relative crystallinity of the parent beta (Beta0) was set to 100%.…”

Preprints in Chemistry: a Research Team's Journey**

“…[41] Reporting a new solvent-free Biginelli reaction series catalyzed by zeolite using the ball mill technique, the preprint (to date downloaded 1,351 times) was published as peer reviewed article three months later in Catalysts. [42] The team went ahead and published four more preprints on the same platform (Preprints), one of which published in two versions (to date, early July 2022, downloaded 933 times [43] ) eventually featured as peer reviewed article with a different title in a paywalled journal [44] owned by a publisher (Wiley) different from the owner of Preprints (MDPI).…”

Biginelli Reaction: Polymer Supported Catalytic Approaches

“…The recovered catalyst was recycled for five consecutive times; up to third cycle catalyst activity was slightly reduced but after fourth and fifth cycle it lost quantitatively. 85 Another convincing protocol utilizing ball-mill technique under solvent free conditions, with short reaction times provided high to excellent yields have found to be added admirable contribution to the developments in the Biginelli reaction.…”