Definition of Green Solvents

The criteria for what determines a green solvent will depend upon the use and ultimate fate of the solvent during the chemical process. Likewise, the determination of what constitutes appropriate solvent usage in green chemistry might include any of the following actions. 

The discussion of green solvents will include chemistry, ecology, and philosophy. The choice of solvents will include new criteria in addition to the traditional considerations of synthesis yield (if we are dealing with reactions), perfect product recovery (separations), or commercial usefulness. 

constitutes an appropriate solvent for green chemistry Fundamentally, it must be a solvent, which allows completion of the task, but in an environmentally conscious manner. Environmental toxicity is a key factor affecting choice of solvents. These chemicals should be minimally toxic to human health and the environment, and should not contribute to pollution (DeVito, 1996a). The considerations for what constitutes a safe solvent might be summarized as follows  

The environmental toxicology of a solvent is affected by many factors. The chemical structure of the solvent could lead to bioavaUability or metabolism, or could enhance the reactivity of the parent molecule. Structure-activity data available for many classes of commercial chemical substances can be nsed as a rational approach for choosing or designing new, less toxic commercial chemical substances. This data is growing and being supported by empirical data. With qualitative structure-activity relationships, it may then be possible to predict a relationship between structure and toxicity and then identify the least toxic members of a class of compounds as possible commercial alternatives to the more toxic substances. 

The grouping of solvents into classes with common characteristics can be useful in focusing attention on features that may play a role in experimental solvent effects. Reichardt s review of classification schemes is thorough (Reichardt, 1988). It is remarkable that solvent classification correlates strongly with the chemist s intuition. The new direction of the science demands that new properties be incorporated into mundane practices. These will include safety properties and environmental properties, as well as chemical properties. 

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