The mechanisms for the base-catalyzed condensation reactions in phenol-formaldehyde resin synthesis were investigated by using the density functional theory method. The structures of the intermediates and transition states, as well as the potential energy barriers of the involved reactions, were obtained. The hypothesis of quinine methide (QM) formation was theoretically confirmed. Two mechanis...

A novel catalytic synthesis of 3,3'-(arylmethylene)-bis-(4-hydroxy-2H-chromene-2-one) derivatives from a tandem condensation reaction of 4-hydroxycoumarin and aromatic aldehydes has been developed. The reaction occurs in water in the presence of Melamine trisulfonic acid as catalyst to give the corresponding products in good to high yields. This green approach has several advantages such as sho...

an efficient green route for the preparation of naphthoxazinones, applying a three-component one-pot condensation reaction of 2-naphthol, aromatic aldehyde and urea in the presence of nano silica supported ferric chloride under solvent-free conditions has been developed. the present procedure offers several advantages such as short reaction time, simple workup, recovery and reusability of the c...

An efficient one-pot condensation for the synthesis of 1,8-dioxo-octahydroxanthene is  achieved through a condensation of aryl aldehydes and 5,5-dimethyl-1,3-cyclohexandione in the presence of  NBS. This method enjoys several advantages such as low cost, simple work up procedure and safe reaction condition. In addition, water was chosen as a green solvent.

a novel catalytic synthesis of 3,3'-(arylmethylene)-bis-(4-hydroxy-2h-chromene-2-one) derivatives from a tandem condensation reaction of 4-hydroxycoumarin and aromatic aldehydes has been developed. the reaction occurs in water in the presence of melamine trisulfonic acid as catalyst to give the corresponding products in good to high yields. this green approach has several advantages such as sho...

 phenytoine derivatives were synthesized , via the  pinacol condensation  with the  reaction of 1,3- diphenyl- propane- 1,3- dione (benzyl) analogs with urea or thiourea in presence of slica gel and solid KOH as Solid phase catalyst  in the mortar / pestle at room temperatures. The reaction was completed at short reaction times (approximately 15min) and pure products were obtained with high yie...

Efficient and one-pot synthesis of 1,8-dioxo-octahydroxanthenes was described by Knoevenagel condensation, Michael addition and cyclodehydration of dimedone. This reaction was carried out through condensation of dimedone and various aromatic aldehydes in the presence of task-specific Brønsted acidic ionic liquid under solvent free conditions. The catalyst could be recycled five times without si...

Efficient and one-pot synthesis of 1,8-dioxo-octahydroxanthenes was described by Knoevenagel condensation, Michael addition and cyclodehydration of dimedone. This reaction was carried out through condensation of dimedone and various aromatic aldehydes in the presence of task-specific Brønsted acidic ionic liquid under solvent free conditions. The catalyst could be recycled five times without si...

A green, efficient, chemoselective, facile and clean procedure is described and discussed for the synthesis of α, α'-bis (substituted-benzylidene) cycloalkanones in solvent-free conditions. The condensation reaction was carried out through the reaction of aromatic aldehydes with cycloalkanones in the presence of Fe3O4@WO3 (Fe3O4@WO3</s...

melamine trisulfonic acid (mtsa) is utilized as a highly efficient catalyst for the solvent-free condensation reaction of 2-naphthol (2 eq.) with arylaldehydes (1 eq.) under conventional thermal as well as microwave conditions to give the d