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 and metal ion complexation. Pure compound qualifies under 2932.99.90.90 as heterocyclic oxygen compound not specifically excluded. Chemically defined per Chapter 29 note 1(a).
Duty Rate — Mexico → United States
110%
Rate breakdown
9903.04.6096.3%Except as provided in heading 9903.04.61, patented pharmaceutical articles as provided for in subdivisions (c) and (d) of U.S. note 40 to this subchapter
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 linear polyethers
• Hygroscopic nature requires <20% RH storage declaration on shipping papers
• Complexing agent registration under TSCA required for first import