engleski

Solvent-free synthesis of pharmaceutically active compounds

Use of mechanical energy in a solvent free environment is promising approach to an alternative preparation of pharmaceutically active compounds and medicinal mechanochemistry [1]. However, to have full control over chemical reaction outcome, it is necessary to understand the mechanistic nature that lies behind it. Recently developed in situ techniques for synchrotron X-ray diffraction and Raman spectroscopy [2] enabled unprecedented insight into the chemical reaction pathways and revealed highly dynamical systems. Different polymorphs occur as reaction intermediates and follow Ostwald’s rule of stages, wherein thermodynamically stable phase is formed from the sequence of metastable phases. Using very small amount of liquid additives as primary alcohols or water a sustainable control and selectivity can be achieved. We present here the co-crystallization of either benzoic acid (ba) or ascorbic acid (ac), also known as vitamin C, with the pharmaceutically active nicotinamide (na). ba and na form four polymorphs [3] while ac and na form two new solid phases. A reaction pathway depends on the reaction conditions, primarily on the amount, polarity and functionality of the added liquid. Using different amounts of liquids changes the reaction mechanism but also enables control of product formation leading to selectivity in this new solid-state synthesis approach. Future research will focus on elucidation of reaction mechanism of this important reactions and further understanding of selectivity based on liquid additives.

mechanochemistry, solvent-free, in situ

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