ABSTRACT
With the exception of some reactions that proceed ef’ciently without solvents, which are discussed in Chapter 3, the vast majority of organic reactions (and almost all extractions) occur in the solution phase. Solvents are used to mediate an even reaction temperature, control reactivity, and facilitate separation and transport of both reagents and products.1 However, many traditional solvents used for
5.1 Introduction .................................................................................................. 131 5.2 Measures of Solvent Greenness .................................................................... 132 5.3 Supercritical Carbon Dioxide ....................................................................... 134
5.3.1 Introduction ...................................................................................... 134 5.3.2 Undergraduate Organic Chemistry Using Supercritical CO2 ........... 136
5.4 Fluorous Solvents .......................................................................................... 138 5.4.1 Introduction ...................................................................................... 138 5.4.2 Undergraduate Organic Experiments Using
Fluorinated Solvents ......................................................................... 140 5.5 Ionic Liquids ................................................................................................. 141
5.5.1 Introduction ...................................................................................... 141 5.5.2 Undergraduate Organic Experiments Using Ionic Liquids .............. 145
5.5.2.1 Preparation of Ionic Liquids .............................................. 145 5.5.2.2 Undergraduate Organic Reactions in Ionic Liquids .......... 148
5.6 Liquid Polymers ............................................................................................ 151 5.6.1 Introduction ...................................................................................... 151 5.6.2 Undergraduate Organic Reactions in Liquid Polymers .................... 153
5.7 Additional Greener Solvents ......................................................................... 154 5.7.1 Introduction ...................................................................................... 154 5.7.2 Undergraduate Organic Experiments ............................................... 154
5.8 Future Outlook .............................................................................................. 158 5.9 Conclusion .................................................................................................... 161 References .............................................................................................................. 161
organic reactions and extractions are Žammable (for example, diethyl ether), toxic (N,N-dimethylformamide), carcinogenic (benzene), readily absorbed through skin (dimethylsulfoxide), environmentally deleterious (chloroform), or some combination thereof. It is understandable how elimination of these solvents from the undergraduate laboratory can improve safety, reduce negative environmental impact, and introduce future chemists to new, or “neoteric,” solvents. This chapter discusses methods to evaluate solvent “greenness,” introduces several greener nonaqueous alternative solvents that have been used in place of more traditional options in the undergraduate laboratory, and describes the comparative greenness of each one. Finally, an outlook on other green solvents that might potentially be implemented into future undergraduate organic experiments is provided.
