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.
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).
ReplyDeleteWe'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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