A Continuously Operated Bimembrane Reactor Process for the Biocatalytic Production of (2R, 5R)-Hexanediol

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 !!!!!

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3 thoughts on “A Continuously Operated Bimembrane Reactor Process for the Biocatalytic Production of (2R, 5R)-Hexanediol

  1. I know what you mean. They claim a yield of 77 % with an e.e. of 99 %. I do believe that is possible. They claim to be able to remove 90 % of the acetone, which is the solvent concentration at 77 %. I have seen systems like this where you are distilling out the acetone but I could appreciate why you wouldn’t want to do this in a continuous process. You would want to keep a tight temperature range so as not to kill the catalyst or the co-factors. They state that the type of membrane was not optimized so there is room for improvement. It is an interesting article, all the same.

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    • It also occurred over 10-13 days, which is awfully long. If it can’t be done any other way, I guess you could tie up a reactor that long. Comments ?

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