Purification of borneol from its isomeric mixture by using metal–organic frameworks

Separation of natural products from their mixture of structurally similar compounds is an important process for drug development and application. Borneol is a natural product widely used in the treatment of the cardiovascular and cerebrovascular diseases, and its production always involve the challenging separation from the diastereomer isoborneol (about 50 %). Herein, elven types of metal–organic frameworks (MOFs) with diverse pore structure and functionalities (–F, –NH2, –SO3H, and –OH) are utilized to evaluate their borneol/isoborneol separation performance, as the first attempt to use MOFs for diastereomers separation. Among these MOFs, UiO-66-F4 exhibits the best performance with the borneol/isoborneol selectivity of 2.23 and the maximum borneol adsorption capacity of 106.88 mg·g−1 at 298 K, owing to the efficient pore confinement of borneol molecule confirmed by molecular simulation. Subsequent column breakthrough experiment demonstrates good separation performance under dynamic conditions. After five-stage purification unit process, high-purity borneol (>96 %) can be obtained. Furthermore, good reusability and scale-up synthesis suggest a high potential of the UiO-66-F4 materials for practical application.