Production of benzaldehyde: a case study in a possible industrial application of phase-transfer catalysis

The conventional method of producing benzaldehyde by direct oxidation of toluene has a major drawback: low conversion to achieve high selectivity. Phase-transfer catalysis (PTC) may be used as an alternative route for benzaldehyde production. In the present study, routes to produce benzaldehyde from benzyl chloride in the liquid phase by using PTC have been examined based on the kinetic data obtained. Using the results of this study and the available information on the conventional route, process design simulations have been carried out for all the routes. While PTC-based processes offer advantages, the study shows that the conventional route appears to be the preferred one for this relatively large-scale organic intermediate with current conversions, selectivities, and chemical costs. However, even minor improvements in one or two PTC steps can greatly enhance the prospects of the PTC route. In general, as the processes get increasingly chemistry intensive, the PTC route becomes increasingly the preferred candidate