New protocols for the synthesis of 5-amino-7-(4-phenyl)-4,7-dihydro-[1,2,4]triazolo[1,5-a]pyrimidine-6-carboxylate esters using an efficient additive

This work introduces a new additive named 4,4’-trimethylenedipiperidine for the practical and ecofriendly preparation of ethyl 5-amino-7-(4-phenyl)-4,7-dihydro-[1,2,4]triazolo[1,5-a]pyrimidine-6-carboxylate derivatives. This chemical is commercially available and easy to handle. It also possesses a low melting point and a broad liquid range temperature, high thermal stability, and good solubility in water. Based on green chemistry principles, the reaction was performed in a) a mixture of green solvents i.e. water and ethanol (1:1 v/v) at reflux temperature, and b) the additive was liquefied at 65 ◦ C and the reaction was conducted in the liquid state of the additive. High yields of the desired triazolo-pyrimidines were obtained under both aforementioned conditions. Our results demonstrated that this additive, containing 2 Lewis base sites and able to act as an acceptor-donor hydrogen bonding group, is a novel and efficient alternative to piperidine, owing to its unique properties such as its reduced toxicity, nonflammable nature, nonvolatile state, broad liquid range temperature, high thermal stability, and ability to be safely handled. Furthermore, this additive could be completely recovered and exhibited high recyclability without any change in its chemical structure and no significant reduction in its activity

Application of TiO2 nanoparticles for eco-friendly biodiesel production from waste olive oil

An environmentally benign, simple, and efficient process has been developed for biodiesel production from waste olive oil in the presence of a catalytic amount of TiO2 nanoparticles at 120°C with a conversion of 91.2% within 4 h. The present method affords nontoxic and noncorrosive medium, high yield of biodiesel, clean reaction, and simple experimental and isolation procedures. The catalyst can be recycled by simple filtration and reused without any significant reduction in its activity

Synthesis of new low-viscous sulfonic acid-functionalized ionic liquid and its application as a Brönsted liquid acid catalyst for the one-pot mechanosynthesis of 4H-pyrans through the ball milling process

In the present study, a new low-viscous sulfonic acid-functionalized ionic liquid (SAIL) viz. 4,4′-trimethylene-N,N′-sulfonic acid-dipiperidinium chloride was synthesized and characterized by FTIR, 1D and 2D NMR, and Mass spectra. Then, some properties of new SAIL were determined including pH, viscosity, density, and solubility in some common solvents. The catalytic activity of new SAIL was demonstrated for the one-pot mechanosynthesis of pyrano[4,3-b]pyrans, dihydropyrano[3,2-c]chromene and tetrahydrobenzo[b]pyrans using planetary ball mill under solvent-free conditions. This current mechanosynthesis methodology for the synthesis of 4H-pyran-annulated heterocyclic scaffolds displays a combination of the synthetic virtues of conventional multi-component reaction with ecological benefits and convenience of a simple mechanocatalytic procedure. New SAIL was easily recycled and reused several times with no significant loss of activity

Efficient chemical fixation of CO2 into cyclic carbonates using poly(4-vinylpyridine) supported iodine as an eco-friendly and reusable heterogeneous catalyst

Green and sustainable synthesis is considered as a safer alternative to the conventional synthetic processes owing to its environmental friendly nature, atom economy, cost-effectiveness, and easy handling. Herein, the catalytic efficiency of poly(4-vinylpyridine) supported iodine (P4VP/I 2 ) as a metal-free and organocatalyst system was studied and approved for an efficient chemical fixation of CO 2 into cyclic carbonates which is performed via the coupling of CO 2 with epoxides. The high conversion and excellent selectivity were obtained for a broad range of epoxides in the presence of catalytic amount of P4VP/I 2 under solvent-free conditions. The heterogeneous catalyst could be recovered and regenerated over several times with no significant loss of catalytic activity. The possible mechanism was described for the catalytic performance of P4VP/I 2 based on the synergetic effect of the Lewis acid and base sites and nucleophilic anion

Microwave-assisted synthesis of pyrrolidinone derivatives using 1,1’-butylenebis(3-sulfo-3H-imidazol-1-ium) chloride in ethylene glycol

The energy efficiency of the microwave-assisted synthesis of pyrrolidinones was demonstrated using catalytic loading of 1,1'-butylene-bis(3-sulfo-3H-imidazol-1-ium) chloride as a sulfonic acid functionalized ionic liquid in ethylene glycol as green solvent. The effect of electron donating and electron withdrawing groups on aniline derivatives was studied under conventional heating and microwave irradiation. Furthermore, the cation effect of ionic liquids containing sulfonic groups on the catalytic efficiency for the synthesis of ethyl-1-phenyl-2-(4-chlorophenyl)-4-hydroxy-5-oxo-2,5-dihydro-1H-pyr-role-3-carboxylate was investigated under conventional heat. The experimental results exhibited that there is a relationship between catalytic efficiency and the number of sulfonic groups and imidazolium moieties linked by carbon spacer. © 2019 N.G. Khaligh et al., published by De Gruyter

Two novel binuclear sulfonic-functionalized ionic liquids: Influence of anion and carbon-spacer on catalytic efficiency for one-pot synthesis of bis(indolyl)methanes

Two new binuclear sulfonic-functionalized ionic liquids with four-carbon spacer were synthesized and their structures were characterized by FTIR, MS, 1H and 13C NMR; then some physical properties and pH of the aqueous solution of new task-specific ionic liquids were determined. Their dual solvent-catalytic activity were studied for the synthesis of bis(indolyl)methanes under mild conditions. The catalytic activity of these ionic liquids were compared with some ionic liquids derived from pyrazinium, piperazinium, benzimidazolium, imidazolium mono- or di-cation containing chloride and hydrogen sulfate as counter anion under optimized conditions. It was proved that the new ionic liquids containing two sulfonic imidazole moieties with four-carbon spacer as well as hydrogen sulfate as acidic counter anion were superior to the previously reported ionic liquids