Promising green solvent

In this chapter supercritical carbon dioxide will be discussed in more detail as one of the most promising green solvents for polymerizations. Subsequently, the possibilities and challenges of applying ultrasound in polymer processes are described. Finally, a short overview of the application potential of polymer processes based on supercritical carbon dioxide or ultrasound technology will be given. 

SCFs are a class of promising green solvents in the development of environmentally benign chemical processes. Scientists and engineers have been very much interested in SCF science and technology in the last decades because of their unique properties and great potential of applications in different fields [4], such as extraction and separation [5], chemical reactions [6], and materials science [7]. Supercritical (sc) or compressed CO2, which is nontoxic, abundant, and nonflammable, can also be used to tune the physical properties of liquid solvents because its solubility in Hquids changes continuously with pressure and/or temperature [8]. 

From an economic and environmental perspective, catalytic aerobic alcohol oxidation represents a promising protocol. The use of molecular oxygen as the primary oxidant has several benefits, including low cost, improved safety, abundance, and water as the sole by-product. In this way, many catalytic systems have been used for the aerobic oxidations in ionic hquids as green solvents. Different types of catalysts or catalytic systems useful for the oxidation of alcohols with as terminal oxidant in ionic liquids as solvent will be discussed below. 

Ionic liquids are emerging as viable media, in in roving various organic reactions as green solvents or catalysts, and have shown promising applications in many chemical processes. This study, for the first time, shows the use of ionic liquid [EtPy][Cp3COO] as an excellent catalyst for the esterification of amino acids. Esterification of several amino acids was achieved with very good yields. 

Carbon dioxide(C02) has emerged these days as the most promising alternative for a green solvent. It provides several benefits It is non-flammable, non-toxic, environmentally benign, and inexpensive. Also, CO2 is a tunable fluid, i.e., its density and solubility can change by controlling pressure and temperature. Supercritical fluid technology has been applied in many and diverse fields... 

Ionic liquids are often considered as promising solvents for clean processes and green chemistry mainly due to their non-volatile character [1,2]. These two catchwords represent current efforts to drastically reduce the amounts of side and coupling products, as well as the solvent and catalyst consumption in chemical processes. As another green solvent concept for chemical reactions the replacement of volatile organic solvents by supercritical CO2 (scCOz) is frequently discussed [3]. 

Lactic acid has been used in the food, chemical and pharmaceutical industries for years, and has the potential to achieve commodity-level status as an intermediate for oxygenated chemicals, "green" solvents, specialty chemical intermediates, and polylactic acid (PLA). PLA, which is already used in medical devices, holds great promise for increased use as a versatile, environmentally-... 

Dandia, A., Jain, A. K., and Laxkar, A. K. (2013). Ethyl lactate lactate as a promising bio based green solvent for the synthesis of spiro-oxindole derivatives via 1,3 dipolar cycloaddtion reaction. Tetrahedron Lett., 54, 3929-3932. 

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