So what is new for today ? I know I shouldn’t be so informal and congenial, but sometimes, I just feel like it. There was an article last year in OPRD, that I thought was worthy of some mention. Lutz et al, “A Continuously Operated Bimembrane Reactor Process for the Biocatalytic Production of (2R, 5R)-Hexanediol”, Organic Process & Development, 2009, 13(6), p. 1202-1205. Before, I get into talking about why I have put this up, I will just throw a reaction scheme underneath.
The following reaction is catalyzed by alcohol dehydrogenase, which is being fueled by the NADPH as a cofactor. The reduction of NADP+ to NADPH is coupled with an oxidation reaction. In this case, it is 1-propanol that is oxidized to acetone. This is a substrate-coupled cofactor regeneration and is subject to Le Chatelier’s principle. The acetone must be removed for this reaction to proceed. The most interesting part of this paper is that it is a continuous process instead of a batch process and it uses pervaporation as a way to remove acetone. What is pervaporation ? I didn’t know until I checked elsewhere.
One could look here: http://en.wikipedia.org/wiki/Pervaporation
Sometimes you have to be careful when you use Wikipedia, but it seems to make some sense this time. So pervaporation is the separation between liquid and vapour phase through a porous or non-porous membrane. The vapour phase permeates through the membrane and due to a partial vacuum being placed on the vapour phase side, it is selectively evaporated. This would upset any equilibrium situation and drive the reaction towards completion. Pretty neat !!!!!