Current Green Chemistry - Volume 4, Issue 1, 2017

Background: The biggest challenge for contemporary organic syntheses is to discover new methods for sustainable, clean and green chemistry. In this context, Poly Ethylene Glycol (PEG) has proven its effectiveness as a potential substitute for reaction media, catalyst or promoter. Owing to its biodegradable and non-toxic nature, it is being actively scrutinized as a green solvent for organic transformation. Method: Polyethylene glycols are readily utilized under mild conditions and have high selectivity and reactivity with broad range of substrate acceptance to make it better reaction medium for a wide variety of organic transformations. Furthermore, it has been revealed in a number of reports that polyethylene glycol can be efficiently combined with other catalyst from the field of organocatalysis or metal - catalysis resulting in synergistic effect. Moreover, polyethylene glycol is stable under high temperature, microwave irradiation and can act as both liquid and solid phase catalyst. Conclusion: This study demonstrates as overview on the most recent advances in the current field.

Background: Quinazoline refers to the class of condensed ring aromatic organic compounds of the heterocyclic series containing benzene ring fused to pyrimidine nucleus. A wide range of biologically active compounds containing quinazoline ring system have also been synthesized by some of the environmental friendly, so called green methods such as synthesis by means of microwave-irradiation reactions, and multi component reactions (MCR) in water under microwave irradiation etc. Methods: The present review article describes synthesis of various derivatives of quinazoline by atom efficient, eco-friendly, solvent-free, high yielding, multicomponent green strategies reported in the literature. Results: These procedures reported in the literature and presented here are compatible with different functional groups. Conclusion: This review article summarizes the recent advances in the synthesis and biological activity investigations of quinazoline derivatives.

Background: Certain heavy metals, in trace or ultra-trace quantities, are nutritionally essential as well as beneficial for a healthy life. This includes Cu, Zn, Fe, Ni, Cr, etc. which in fact although required by the living body in minute quantities but become toxic in larger dosages. Besides, heavy metals such as Pb, Hg, As, Cd are most often responsible to human poisoning. Method: Most of them accumulate and travel up the food chain when discharged into surface water bodies from industrial, agricultural as well as domestic effluents due to man-made activities. In certain cases, they are also contaminated through natural causes such as soil/rock erosion, and salination too. These heavy metals through various means percolate into groundwater, thereby contaminating drinking water - which of-course, is a very important global issue to be concerned about. Result: To accomplish distribution of clean and fresh drinking water and promote wastewater management, varieties of green chemistry based- techniques as well as methodologies for heavy metal ion remediation are being employed today. Conclusion: This review aims at highlighting the commonly existing green- technologies adopted for remediation of heavy metals to obtain purified water.

Background: Interest for the Diels-Alder (DA) reaction has steadily increased over the time and the end of this remarkable development is not yet in sight. From its discovery on, the DA reaction has evolved through different stages of development, and since the beginning of the 21st century catalytic Diels-Alder reactions remains obviously one of the main areas of research. Methods: As there are striking similarities in the catalysis of both DA and Friedel-Crafts reaction, we therefore anticipated that DMF (a weak Lewis base) and iodine (a weak Lewis acid) could act synergistically and smoothly in the DA reaction, and we selected the cyclo-addition of maleimide to anthracene- 9-methanol as our benchmark reaction in order to be able to accurately compare our actual data with the results of our previous publications. Results: Based on Pearson's SHAB (Soft and Hard Acids and Bases) theory, we have first established that the Diels-Alder cyclo-addition of our benchmark reaction (anthracene-9-methanol and maleimide) is a process submitted to generalized acid-base catalysis and in a second step we have developed within the context of the Green Chemistry an original efficient catalyst i.e. the DMF.I2 complex where DMF acts as Lewis base and iodine as Lewis acid. In order to expand the scope of title catalyst, the cyclo-addition of tetracyclone with N-phenylmaleimide was carried out successfully using DMF.I2 in n-butanol and led to both endo and exo adducts in good yields. Conclusion: It is noteworthy that the molar ratio of diiodine vs. dienophile can be successfully scaled down to 10% without significant detrimental effect on the time of reaction and final yield (1 h, 100°C, 93%).

Background: Solvent-free reaction for the synthesis of thiobarbituric acids (TBAs) by the reaction of 1,3-disubstituted thioureas and malonyl chloride using Amberlyst-15 as a green catalyst has been reported. Recyclability of the catalyst was possible up to five runs without loss of catalytic activity. Conclusion: The simple workup, isolation without column, excellent yields, is main advantages of present protocol.