In the Mack lab a form of mechanochemistry called high-speed ball milling is used in order to avoid harmful solvents, which are a major source of hazardous waste. Over 3 billion pounds of solvent waste was produced in 2012 according to the EPA, which accounts for almost 25% of all chemical waste produced that year. Chemical waste is detrimental to the Earth’s environment. If we are able to run a reaction without using these harsh solvents a decent portion of the total waste would be eliminated. After any reaction, we must separate the product mixture. Normally wet column chromatography would be used. Since that requires the use of harmful solvents, the goal is to find an alternative to this separation process. In order to avoid chromatography altogether, a functionalized polymer is incorporated into the experiment. This functionalized polymer can be separated from the product mixture by simple filtration using a green solvent. This method was tested using the Wittig reaction. In order to carry out the Wittig reaction, one needs an alkyl halide, an aldehyde, triphenylphosphine, and a base to yield desired alkene products plus triphenylphosphine oxide. In order to bypass the inconvenience of separating triphenylphosphine oxide from the desired alkene products, a polymer-bound triphenylphosphine was used. This led to the byproduct being attached to the polymer that remained in the filter paper after the isolation process. Our system was successful in producing alkenes from various aldehydes in good yield.

Polymer bound Wittig reaction under solvent free ball milling conditions

249th National Meeting (2015)

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