Crown Ether 18-Crown-6 from Mexico
18-Crown-6 is a macrocyclic polyether with six oxygen hetero-atoms in 18-membered ring, used for phase transfer catalysis. HTS 2932.99.90 covers as other oxygen heterocyclic compounds. Excluded from acyclic ethers of heading 2909.
Duty Rate — Mexico → United States
3.7%
Rate breakdown
9903.03.030%Articles the product of any country, as provided for in subdivision (aa)(ii) of U.S. note 2 to this subchapter
Import Tips
• Molecular weight certification confirms macrocyclic structure vs. oligomer mixtures
• Research chemical; Letter of Intent for lab use prevents commercial classification
• High cost item; accurate invoicing prevents undervaluation scrutiny