Abstract: In this study, we investigated the preparation of highly pure D-borneol from the essential oil extracted from the leaves of Dryobalanops aromatica through steam distillation. Crude D-borneol was obtained after the essential oil was subjected to freeze-drying and centrifugation. Then, the crude product was purified by recrystallization in petroleum ether, 120# gasoline, and anhydrous ethanol, respectively. The chemical composition, optical rotation, morphology and thermal properties of the as-obtained crystals were characterized. The results showed that the content of D-borneol in the essential oil was about 68.10%, and its purity was more than 98% after recrystallization. There were no obvious differences in mass spectrum or optical rotation between D-bormeol standard and the solvent recrystallized crystals. The appearance of the petroleum ether and gasoline 120# recrystallized crystals showed regular hexagons with clear boundary, while the ethanol recrystallized crystal was irregularly and granularly dispersed or aggregated. However, the results of thermal analysis showed that the thermal properties of all three recrystallized crystals were the same, indicating that the appearance of crystals did not affect their thermal performance. Furthermore, Mo’s equation could describe the non-isothermal crystallization process of D-borneol crystal. This study can provide an important technical reference for the exploitation and utilization of Dryobalanops aromatica and the production of high-purity D-borneol.

Key words: Dryobalanops aromatica, D-borneol, recrystallization, crystal morphology, high purity