Optimizing Selective Partial Hydrogenations of 4-Nitroacetophenone via Parallel Reaction Screening

The hydrogenation of 4-nitroacetophenone was optimized for selective reduction to the corresponding aniline-ketone (97%), aniline-alcohol (95%), and aniline-methylene (99%) as a case study demonstrating the optimization of the selective reduction of a polyfunctional substrate using a parallel pressure reactor. The catalyst, catalyst loading, pressure, temperature, and methanesulfonic acid stoichiometry were varied, first in an initial coarse screen (catalyst and acid stoichiometry), and then in a full factorial screen for selected catalysts. Facile profiling of hydrogen uptake in each reaction aided setting reaction time and parameter ranges for the full factorial analysis, allowed for quickly spotting under- and overreduction, aided predicting robust reaction endpoints, and provided data for analyzing kinetic behavior.