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A new polymorph of 1-hydroxy-2-naphthoic acid obtained during failed co-crystallization experiments
Qi Zhang1, Meiqi Li1, Xuefeng Mei1
1Pharmaceutical Analytical and Solid-State Chemistry Research Center, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zu Chong Zhi Road, Zhang Jiang High-Tech Park, Shanghai 201203, People's Republic of China.
Researchers discovered a new, more stable crystal form of 1-hydroxy-2-naphthoic acid (HNA). This finding is important for pharmaceutical co-crystal preparation and understanding HNA polymorphs.
Area of Science:
- Solid-state chemistry
- Pharmaceutical sciences
Background:
- 1-hydroxy-2-naphthoic acid (HNA) is a key pharmaceutical salt-forming acid.
- HNA is frequently utilized in the preparation of pharmaceutical co-crystals.
Purpose of the Study:
- To report the discovery and characterization of a new polymorph of HNA.
- To establish the thermodynamic relationship between the known and new HNA polymorphs.
Main Methods:
- Attempted co-crystallization experiments to induce polymorphism.
- Full characterization of the new and reported HNA forms.
- Thermodynamic analysis to determine stability relationships.
Main Results:
- A novel polymorph of 1-hydroxy-2-naphthoic acid was successfully obtained.
- The new HNA polymorph was fully characterized.
- A monotropic relationship was established, with the new form exhibiting greater thermodynamic stability.
Conclusions:
- The discovery of a new, more stable HNA polymorph expands the understanding of its solid-state properties.
- This finding has implications for pharmaceutical co-crystal design and manufacturing processes.
- The characterized HNA polymorphs provide valuable data for solid form screening and selection.
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