Choice Of Solvents

The principal functions of a solvent are to (1) provide a practical homogeneous reaction mass, (2) act as a heat-transfer agent, and (3) cause products or by-products to precipitate out, thereby improving the yield.

Chemicals under the 33/50 program started by the EPA in February 1991 should be avoided. The solvent should be chosen based on environmental grounds (ease of workup and solvent recovery) and then on optimizing in that solvent.

Less-hazardous organic solvents, such as ethyl acetate and isopropylacetate, should be used in place of more toxic (or more rigidly controlled by the EPA) solvents, such as methylene chloride and benzene. The current trend is to replace chlorinated solvents with nonchlorinated solvents.

Table 3.6.1 provides a set of general rules for the biodegradability of some organic molecules.

The use of polar solvents such as dimethyl sulfoxide (DMSO) or dimethylformamide (DMF) should be minimized. These solvents speed up many reaction rates, but

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