Pharmaceutical Intermediate: Hydroxypropyl-beta-cyclodextrin

Pharmaceutical Intermediate: Hydroxypropyl-beta-cyclodextrin - HPBCD - News - Shandong Binzhou Zhiyuan Biotechnology Co.,Ltd

Hydroxypropyl-beta-cyclodextrin is an ether derivative of beta-cyclodextrin. The introduction of hydroxypropyl groups opens the hydrogen bonds in the beta-cyclodextrin molecule, forming an amorphous mixture, which greatly improves the water solubility. It has been proved to be highly safe and can even be used for intravenous injection. Hydroxypropyl-beta-cyclodextrin is therefore considered to be a potential alternative to the parent cyclodextrin. The cyclodextrin is condensed with propylene oxide under alkaline conditions. Under the base catalysis, the cyclodextrin alkoxy anion attacks the carbon atom with the least substituent on the oxygen ring, and the steric hindrance is the smallest. Cyclodextrin and propylene oxide react easily in a strong alkaline environment to form a 6-substituent, and under weak alkaline conditions, a 2-substituent is easily formed. The hydroxyl groups at positions 2, 3, and 6 are activated under strong alkaline conditions, and the steric hindrance at the 6 position is the smallest, and the substituent is easily accessible. Under the weak alkaline condition, the hydroxyl group at the 2 position is the strongest and easy to activate, so the substitution is mainly in the 2 position. It has long been believed that the structure of cyclodextrin and its derivatives is rigid, a hypothesis that does not conform to the nature of the complexes they can easily form. Its structure is relatively flexible, and experiments have shown that cyclodextrin forms a complex by non-covalent bonding not only in solution, but also in a solid state. The introduction of hydroxypropyl opens the internal hydrogen bond of beta-cyclodextrin, making the backbone flexible and the substituents also have some activity space. This relatively flexible structure can better explain the improvement of the composite forming ability and the composite reaction kinetics.