Tuesday, 19 July 2011
Nitrile hydration is exothermic
I spotted a reference to the fact that the hydration of a nitrile is an exothermic process, and as such at scale needs some form of refrigeration. Obviously this is an issue in biocatalytic processes where your enzyme might be thermal sensitive but is also true of the plants which operate the copper based chemical process (like the one I was shown round in Bradford then run by Ciba- thanks Yvonne!).
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I used Hyperchem running a semiempirical PM3 method to model the process of conversion of acrylonitrile, benzonitrile and nicotinonitrile to the relevant amide and they all give an exotherm of about 20kcal per mole. I repeated one using a moderately intensive DFT expt and it agreed with this figure.
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2 comments:
Hi Justin,
I remember a presentation of a guy from Lonza (dont remember his name now) that mentioned that they had to cool their enzymatic reaction quite vigorously to prevent the reaction mixture from heating up.This was for nicotinonitrile hydration.
Sander
That's interesting. My calculations were trying to see if there was anything special about acrylonitrile but the numbers were pretty much the same for the aromatic nitriles as well. Interesting to hear that in real life cooling is needed for nicotinonitrile too. I set an intern away doing some rough isothermal microcalorimetry on NHase a few years back, and the amount of heat he saw was very noticeable... I thought it was a very different scale though!
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