Wednesday, May 18, 2011

Process Wednesday: no special solvent for you!

Want to buy that super-duper ultra pure solvent for your reaction in the lab? Our mentor-by-literature, Neal Anderson, says you're out of luck, bucko (from pg. 102 of  "Practical Process Research and Development"):
For initial laboratory investigations, whenever possible use solvents from bulk supplies that have been purchased for routine processing. Avoid special grades of solvents, such as HPLC-grade solvents, as processing may changes when reactions are run in bulk solvents, due to differing impurities and impurity levels.  
Using a higher grade of solvent may not be necessary. [snip] Once a special grade of solvent has been shown to be necessary, the purchase of the more costly material is readily justified. 
Well, drat. So unless you're willing to purchase that super-duper ultra pure grade by the rail car (hopefully you'll be buying it by the rail car, anyway), you're better off with the normal stuff.

2 comments:

  1. Two in particular to be careful of when doing process development are ethanol (checking solvent used to denature it) and heptane (plant heptane may be a mix of isomers instead of just n-heptane - which can nicely mess up that isolation developed in the lab).

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  2. We're trying to optimize a kilo-scale prep in DMSO, and coming up against the spec being very different between bottles of reagent-grade and 55-gallon drums.

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