Friday, June 15, 2012
In Walt's Method for making crystal meth, how is the chirality introduced?
We never hear about the enantiomeric excess for Walt's crystal meth synthesis. We often hear about the overall chemical purity, often > 99%. For those not chemists, a chiral center is a carbon that has four different things attached to it, or at least that is one way to achieve chirality. Walt briefly mentions chirality when Victor was trying to "cook" a batch of meth in "Boxcutter." However, Walt didn't go into detail of how he achieved his asymmetric synthesis.
Walt starts with achiral starting material such as methyl amine and phenyl acetone. How Walt achieves an enantiopure product puzzles me. A catalyst is one way to achieve an asymmetric synthesis but Walt's catalyst, thorium oxide, is not chiral so that cannot be the source of the asymmetry.
Some may say I'm being pedantic for fretting about the enantio-purity of the product, but it does matter. For an example, look at the history of thalidomide, a anti-nausea drug whose enantiomer caused birth defects.