Sometimes, a process may require high temperature at which inexpensive phase-transfer catalysts may decompose. In such cases, the PTC application may be feasible using a more thermally stable phase-transfer catalyst. Chemists may be reluctant to try these catalysts because they are more expensive. A common mistake is to be concerned with the cost per kg of catalyst instead of the cost of the catalyst per kg of product. Other scale up issues need to be addressed in PTC systems, most notably agitation and heat transfer, both of which are always scale up issues.
Agitation can also be an issue in solid-liquid PTC systems.
Any combination of the above reasons may truly render a PTC process option not feasible. Those who say that development time is at a premium should remember that increased profit is a premium. The development investment must be weighed against the potential benefit. Decisions at all stages should be made according to the anticipated return on investment. The second most potent antidote is an energetic charismatic champion armed with piles of firmly conclusive data and testimony to support the change.