Characterization and solventless growth of salicylic acid macro‐crystals involving a nitrogen gas flow

Abstract

We report an original solventless thermal crystallisation method to grow large needle-like salicylic acid (SA) crystals of 10-12 mm in length. The method is based on the utilization of nitrogen gaz flow on salicylic acid powder during heating just below melting point temperature for 24 h. Salicylic acid provides one of the best examples of a pharmaceutical substance used for cosmetics whose physical and chemical properties indicate hydrogen-bond formation between the hydroxyl group and an adjacent oxygen atom of the same molecule. The structure of the crystals is confirmed by single crystal X-ray diffraction; it is monoclinic, a=4.93(2) Å, b =11.23(5) Å, c=11.56(6) Å, β = 90.77(4)° with the space group P2 1 /c. The macrocrystals formation using this method is new and represents an interesting finding for a wide range of applications to be developed in the fields of biotechnology and photonics.