The Rowan Solvent Greenness Index Method

Another solvent scoring method proposed by Slater and Savelski [1] used a single, customizable solvent index that accounted for twelve different environmental parameters. The parameters used for the Rowan Solvent Greenness Index Method are  

The solvent parameter and property values used in this method were estimated from several industrial and professional sociehes and government sources. The environmental index for each of the twelve parameters is calculated and normalized on a zero-to-one scale [1]. Depending on whether high or low values for the parameters prove to be greener , Equation 3.7 or Equation 3.8 is used, respectively. In Equations 3.7 and 3.8, x in and x ax are the minimum and maximum value of a specific parameter for all solvents contained within the Solvent Greenness Scoring Index database, Xj is the value of a parameter for solvent i, and Mj is the scaled value of metric M for solvent i [1]. 

The values for each solvent metric, M, are then summed into an overall solvent index (OS I) as shown in Equation 3.9. Prior to their summation, each parameter index can be arbitrarily weighted (a,) to focus on those factors which are more important to a particular industry or process. Equation 3.10 displays the OSI recommended for use by the pharmaceutical industry [1]. 

The OSI is further normalized on a zero-to-ten scale using Equation 3.11. 

In Equation 3.11, y is the OSI of solvent i, and y dn and Ymax are the minimum and maximum values of OSI, for all solvents in the database. The final weighted solvent greenness index score is then obtained by mulhplying the OSfo, by the mass of solvent i used. 

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