Clean synthesis in water: uncatalysed preparation of ylidenemalononitriles

An eco-friendly procedure for the efficient synthesis of arylidinemalononitriles and 4,4′-(arylmethylene)bis(3-methyl-1-phenyl-1H-pyrazol-5-ols) in aqueous media

“…Furthermore, Bigi's group described the same reactions which could proceed efficiently in water (12). More recently, we found that aldehydes reacted with malononitrile efficiently in the absence of catalyst and solvent under microwave irradiation and thermal heating conditions (13).…”

“…Further, Elinson et al (23) utilized electro-catalytic procedure for its synthesis. However, most of the methods suffer from at least one limitation that may include moderate yields, long reaction times, harsh reaction conditions or tedious workup procedures (12). Recently, the use of LiOH ×H 2 O has received considerable attention as a cheap and easily available reagent in organic reactions.…”

Aqueous Suspension of Basic Alumina: An Efficient Catalytic System for the Synthesis of Poly Functionalized Pyridines

“…knoevenagel condensation can be easily achieved in protic solvents like water without need of any catalyst though the net result is dehydration 19 whereas the sub subsequent steps presumably involves Michael addition, s-Alkylation and cyclization which requires intervention of catalyst, since uncatalyzed reaction does not lead to final product. Hence, although basic alumina was found to be an effective solid medium for the model reaction in water, variety of solid promoters such as neutral alumina, acidic alumina, silica gel and amorphous silica were examined in order to improve the efficiency of results obtained in our initial study.…”

Tetrabutylammoniumbromide mediated Knoevenagel condensation in water: synthesis of cinnamic acids

“…Very few Knoevenagel condensations using water as solvent have been reported. 10,11 However, no reaction utilizing water as solvent has been reported for the synthesis of cinnamic acids. In recent years, MW activation coupled with phase transfer catalysis 12 using water has emerged as a highly efficient and environment-friendly methodology as on cooling, products are separated out and are generally in a state of high purity.…”