This PTC Tip of the Month has helped many of our customers save large amounts of money, mostly by reducing excess expensive and/or hazardous raw materials while maintaining high yield and high throughput. The diagram is taken from the group exercise on page 108 of the course manual of “Industrial Phase-Transfer Catalysis.”
This graph shows the disappearance of benzoyl chloride as a function of agitation speed (in a small lab reactor) for the reaction of aqueous sodium phenoxide with benzoyl chloride in the presence of tetrabutylammonium hydrogen sulfate.
At low rpm, this PTC reaction is transfer rate limited (“T-Reaction”). In the T-Reaction regime, more agitation increases mass transfer of the phenoxide from the aqueous phase into the organic phase and reactivity increases. At some point when increasing agitation efficiency, the rate of consumption of phenoxide in the organic phase by the intrinsic reaction is slower than the rate of phenoxide transfer. In other words, the rate determining step shifts from mass transfer (“T-Reaction”) to the intrinsic nucleophilic substitution in the organic phase (“I-Reaction”).
In the I-Reaction regime, further increase in agitation efficiency does NOT increase throughput since the rate determining step is not no longer limited by transfer.
The sharp increase in the disappearance of the benzoyl chloride at the right side of the graph represents non-catalyzed interfacial hydrolysis of the benzoyl chloride.
In other words, if you think that you must agitate 2 phases as much as possible and you have water-sensitive reactant, all you are doing is causing you purchasing manager to waste money on more benzoyl chloride (in this case).
This exercise is taught in the 2-day PTC course to give you the ammunition to convince your engineers to reduce the agitation efficiency of your 2- or 3-phase PTC systems when you have water-sensitive reactants or products.
Now register for the 2-day course “Industrial Phase-Transfer Catalysis” in order to learn dozens of specialized PTC techniques, like this one, so you can improve your personal performance in process development and plant support. This rare public PTC course (most PTC courses are conducted in-house due to the obvious high value) will be conducted in Prague on October 15-16, 2019 and you can enjoy a 15% discount by registering and paying before June 30, 2019.
Still not sure if you want to attend? Examine the PTC course agenda and you will understand why this is such a powerful course that helps you improve profit performance and R&D efficiency!
