Iranian Journal of Catalysis
Volume:2 Issue: 4, Autumn 2012

α-Amino nitriles are synthesized in a one-pot, three-component coupling of aldehydes (or ketones), aniline, and trimethylsilyl cyanide using a catalytic amount of choline chloride.2ZnCl2 as a bio Lewis acidic ionic liquid. Mild Lewis acidic characteristic of this ionic liquid allows efficient synthesis of α-amino nitriles from acid sensitive aldehydes.

Silica sulfuric acid as an efficient and reusable heterogeneous catalyst has been used for the preparation of amidines 2 from formimidate 1 by reaction with aromatic amines at room temperature in good to excellent yields. Imidate was prepared by treatment of equimolar quantities of triethyl orthoformate and diaminomaleonitrile in refluxing dioxane. All the compounds were characterized fully by spectroscopic techniques.

Various types of aldehydes undergo crossed-aldol condensation with ketones in the presence of melamine trisulfonic acid (MTSA) under solvent-free conditions. The reported method is mild, efficient and has the advantages such as using heterogeneous catalysis, short reaction times, high yields of the products and the recyclability of the catalyst.

Nicotine-based ionic liquid has been used as a green catalyst for pyridine-catalyzed Huisgen reaction. It promoted addition of dimethylacetylenedicarboxylate to aldehydes or N-tosyl imines leading to efficient synthesis of 2-benzoylfumarates and 1-azadienes respectively under pyridine free odorless ionic liquid conditions. The improved results were obtained in terms of enhanced yields, with minimal work up.

In the present of methylimidazolium hydrogen sulfate, the synthesis of arylidene heterobicyclic pyrimidinones is studied by condensation of aromatic aldehyde, cyclopentanone, and urea or thiourea. Using solvent-free conditions, non-toxic and inexpensive materials, simple and clean work-up, short reaction times and good yields of the products are the advantages of this method.

The hydrolysis of sodium borohydride as a source of hydrogen gas is studied at different mole ratios of H+ to NaBH4. The sulfonated porous carbon (SPC) is used as a source of hydrogen ion and catalyst. It is found that the sulfonated porous carbon exhibits high activity for the hydrolysis of NaBH4 to generate hydrogen gas at room temperature in comparison to Amberlyst-15 and Nafion-NR50. The kinetic rate constant of hydrolysis reaction is calculated by measurement of the evolved hydrogen gas as a function of time. The kinetic rate constant of NaBH4 hydrolysis is approximately increased 7.6 times at presence of SPC as a solid acid/catalyst versus blank hydrolysis reaction. The activation energy of sodium borohydride hydrolysis is obtained 1.24 KJmol-1.The kinetic rate constant (kapp, s-1) of hydrogen generation reaction increased from 0.023 to 0.626 with increasing of H+(SPC)/NaBH4 from 0.25 to 1.50. The SPC activity with mole ratio of H+/NaBH4=1 show an efficiency of 91% at time 25s.

A convenient and efficient direct protocol for the preparation of antibacterial azo dyes by the reaction of 2-naphthol with aromatic amines in the presence of catalytic amount of N-methyl-2-pyrrolidonium hydrogen sulfate ([H-NMP]HSO4) was carried out under solvent free conditions. This method has some advantages such as: easy work-up and easy separation of catalyst from the reaction mixture. The in vitro antibacterial activities of some compounds were studied using gram positive and negative microorganisms.

Benzyltriphenylphosphonium bromide (BTPB) has been applied as an efficient catalyst for the preparation of bis(indolyl)methanes (BIMs) via electrophilic substitution of indoles with aldehydes in the absence of solvent.