Silica Gel Supported Sodium Hydrogen Sulfate as an Efficient and Reusable Heterogeneous Catalyst for the Synthesis of Imines in Solvent-free Conditions under Microwave Irradiation

Abstract

This synthesis of imines has been carried out efficiently by the condensation of carbonyl compounds with amines in the presence of silica gel supported sodium hydrogen sulfate (NaHSO4.SiO2) as a heterogeneous catalyst under microwave irradiation in solvent-free conditions. NaHSO4.SiO2 can be recovered and re-used up to ten times by simple washing with diethyl ether after each use and activated in an oven at 120 °C for 1 h, thus rendering the process more economical.

Easy-to-execute 'One-pot' Synthesis of 1,2,4,5-Tetrazines Catalyzed by Activated Fly Ash

“…The physical properties, such as specific gravity and specific surface area, of fly ash used were 1. 9 The purpose of the present investigation is to activate the as-received fly ash by physical method followed by thermal method (Fig. 1) and to study the influence of activated fly ash to catalyze threecomponent coupling of thiourea/urea, various structurally diverse aromatic aldehydes and ammonium acetate to form 6-aryl-1,2,4,5-tetrazinan-3-thiones/ ones.…”

“…8 Owing to our interest in solid-state reactions, 9 we attempted to use activated fly ash to catalyze three-component coupling of thiourea/urea, various structurally diverse aromatic aldehydes and ammonium acetate to form 6-aryl-1,2,4,5-tetrazinan-3-thiones/ones, which possess antimicrobial activity.…”

A Green Chemical Approach towards the 'One-Pot' Synthesis, Spectral Characterization and in Vitro Antibacterial and Antifungal Activities of Morpholino Pyrimidines

“…A general way to improve synthetic efficiency and also to give access to a multitude of diversified molecules is the development of domino reactions which allow the formation of complex compounds starting from simple substrates in a single transformation consisting of several steps. Silica gel supported sodium hydrogen sulfate (NaHSO4.SiO2), a non-toxic and inexpensive catalyst, has been used for one-pot conversion of ketones to amides, 24 synthesis of imines, 25 one-pot synthesis of 1,2,3-selenadiazoles, 26 1,2,4-triazolidin-3-thiones 27 and Knoevenagel condensation reactions. 28 Owing to our interest in synthesizing fascinating pharmacological and therapeutic important compounds under microwave assisted reactions, [24][25][26][27][28] we attempt and succeed now to use silica gel supported sodium hydrogen sulphate (NaHSO4.SiO2), as a heterogeneous catalyst for the one-pot synthesis of morpholino pyrimidines (10-18) in dry media under microwave irradiation and their in vitro microbiological evaluation is carried out against clinically isolated bacterial and fungal strains.…”

Novel one-pot synthesis of 1,2,4-triazolidin-3-thiones comprising piperidine moiety

“…Silica gel supported sodium hydrogen sulfate (NaHSO 4 .SiO 2 ), a non-toxic and inexpensive catalyst, has been used for one-pot conversion of ketones to amides, (23) synthesis of imines, (24) single-step synthesis of 4(3H)-quinazolinones (25) and one-pot synthesis of 1,2,3-selenadiazoles (26).…”