(18a) Approach for the Development of a More Efficient and Safer Process in the Pharmaceutical Industry

Risks are present in chemical reactions due to the properties of the chemicals and the potentially hazardous situations that can develop under abnormal conditions. These reactions are employed in industrial processes, but a need exists to improve technologies and find alternatives that lead to safer operations. The catalytic N-oxidation of alkylpyridines using hydrogen peroxide as an oxidizing agent is such a process in need of improvement. The N-oxidation reaction is widely used in the pharmaceutical industry; however, a safety issue must be addressed in this process: the very condition-sensitive, undesired decomposition of hydrogen peroxide which produces oxygen and water. The hazards are related to the generation of oxygen, since it can cause the reaction vessel to over-pressurize and can lead to serious explosions and fires because it is combined with the flammable properties of alkylpyridines. Previous experimental studies on this reaction exist, but the separation of phases in the reaction mixture has hindered the description of the kinetic model that represents the reaction and helps in the prediction of runaway scenarios. In order to overcome the operating limitations and hazardous conditions, a methodology is developed, where phase equilibrium and calorimetric studies are combined. The Gibbs minimization method is used to investigate the phase diagrams of the alkylpyridine-water and alkylpyridine-water-catalyst systems. Experiments in an adiabatic calorimeter are performed to assess the safety parameters of the N-oxidation of low order alkylpyridines (picolines). The purpose of this work is to find a new set of operating conditions where the phase separation and decomposition reactions are suppressed. The conditions will be selected based on three important aspects: the viability of performing the operation at industrial scale, the efficiency of the reaction, and the operational safety under the new conditions.