How Safe and Green Is My Reaction?

blog post

For our Green Chemical reaction at #solo2010 ( )

I’d like to be able to calculate the “greenness” of a reaction. This is obviously subjective, but should illustrate the principles and components of green chemistry even if it’s not completely worked out. Bob Hanson (of Jmol / BlueObelisk fame) has created a Green Chemistry Assistant that calculates Process Mass Efficiency (PME) and Atom Efficiency. Bob’s done great work for getting students involved with thinking about Green Chemistry. I asked him about the nature of the materials as well (e.g. toxicity, flammability) but the calculator doesn’t do this.


To give an example, here’s our first reaction:

The title compound [1] was synthesized as described in the literature. To glycine (1.00 mol) and potassium hydroxide (1.00 mmol) in 10 ml of methanol and 5 ml of water was added 2-hydroxy-1-naphthaldehyde (1.00 mmol in 10 ml of methanol) dropwise. The yellow solution was stirred for 2.0 h at 333 K. The resultant mixture was added dropwise to Cu(II) nitrate hexahydrate (1.00 mmol) and pyridine (1.00 mmol) in an aqueous methanolic solution (20 ml, 1:1 <i>v</i>/<i>v</i>), and heated with stirring for 2.0 h at 333 K. The brown solution was filtered and left for several days, brown crystals had formed that were filtered off, washed with water, and dried under vacuum.

We can’t address yield (it wasn’t given and crystallographers don’t need lots of stuff – purity is more important. However it uses methanol and pyridine and several other compounds you will find in Wikipedia – which have some modest hazards associated with them. Anyone doing this in Universities and Industry has to prepare a safety assessment (COSHH in UK) before doing the work. Can we create a numerical index of safety from the form??

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