engleski

Physico-chemical steering towards greener processes - optimization of Omeprazole synthesis

Omeprazole is a trivial name for 6-methoxy-2-[(4- methoxy-3, 5-dimethylpyridin-2- yl)methanesulfinyl]-1H-1, 3-benzodiazole, an active pharmaceutical ingredient. This compound was the first proton pump inhibitor on the market, and is considered by the WHO to be one of the essential medications. Production of omeprazole usually follows the route shown below. The preparation procedure is conducted as a one- pot synthesis involving condensation of the benzimidazole moiety with pyridine moiety in reflux conditions, followed by the addition of appropriate catalytic compounds. The aim of this work was to modify the synthetic route according to the guidelines attained through thermodynamic and kinetic studies of both phases in the one-pot procedure, with the emphasis on the solvent effect. It has been shown that the MeOH/H2O ratio has dramatic effect on the first- step reaction rate which can in principle be used to carry out the reaction at room temperature almost ten times faster. In addition, the increase of water content leads to a lower product solubility which eventually results in higher reaction yields. In the second phase, i.e. oxidation step, it has been proven that after pH correction in order to maximize precipitation of omeprazole as the neutral species, relatively long trituration periods have virtually no effect on the overall yield and purity profile, and is thus unnecessary.

omeprazole ; synthesis ; solvent effect ; kinetics ; thermodynamics

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