Which option is more environmentally friend and why: a reaction that requires the product to be dried versus one that does not require a drying agent?

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ncchemist | eNotes Employee

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The two most common drying agents used in basic organic chemistry are magnesium sulfate (MgSO4) and sodium sulfate (Na2SO4).  Both are inorganic solids that will dissolve when added to pure water.  Generally speaking, a reaction that does not require a drying agent for the product would be more environmentally friendly for 2 main reasons.  The first is the fact that you don't have excess drying agent at the end that you have to dispose of either as a solid waste or dissolved in wastewater.  Even though both agents dissolve in water, adding uneccessary sulfate salts to the water supply is preferable.  The other reason is that in order to use a drying agent you have to dissolve your product in organic solvent which will eventually have to be gotten rid of as hazardous waste.  It will ultimately end up in an incinerator and produce waste gasses including CO2.  So if you can choose a reaction that doesn't require a drying agent that would be preferable from an environmental point of view.