• Solid-State Competitive Destabilization of Caffeine Malonic Acid cocrystal: Mechanistic and Kinetic Investigation

      Alsirawan, M.B.; Lai, X.; Prohens, R.; Vangala, Venu R.; Pagire, S.K.; Petroc, S.; Bannan, T.J.; Topping, D.O.; Paradkar, Anant R. (American Chemical Society, 2020-12-02)
      The main objective of this research is to investigate solid-state destabilization mechanism and kinetics of the model cocrystal caffeine : malonic acid (CA:MO) in presence of oxalic acid (OX) as a structural competitor. Competitive destabilization of CA:MO and subsequent formation of CA:OX takes place at temperatures significantly below its melting point. Destabilization mechanism was found to be mediated by sublimation of both CA:MO and OX. During CA:MO destabilization, free CA could not be detected and direct transformation to CA:OX cocrystal was observed. The destabilization kinetics follow Prout-Tompkins nucleation and crystal growth model with activation energy of 133.91 kJ/mol and subsequent CA:OX growth kinetic follow Ginstling – Brounshtien diffusion model with activation energy of kJ/mol.