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
13.7%
Rate breakdown
9903.05.5510%Except for products described in headings 9903.05.85–9903.05.92 and 9903.05.94, articles the product of Mexico, as provided for in U.S. note 52 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