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!).

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.