Crown Ether 18-Crown-6
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.
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More Specific Codes
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Alternative Classifications
This product could be classified differently depending on its characteristics or intended use.
If ring size <12 members
Smaller cyclic ethers classify as acyclic ether derivatives in 2909.
If dissolved in acetonitrile for chromatography
Lab solutions constitute preparations of Chapter 38.
If nucleic acid derivative function predominates
Compounds with additional heteroatoms may shift to later heterocyclic headings.
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Import Tips & Compliance
• 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
Related Products under HTS 2932.99.90
Trioxane Pharmaceutical Intermediate
Trioxane is a heterocyclic compound with oxygen hetero-atoms forming a six-membered ring, used as an intermediate in pharmaceutical synthesis. It falls under HTS 2932.99.90 as a heterocyclic compound with oxygen hetero-atoms only, not elsewhere specified in heading 2932. This classification applies to pure chemical forms without additional functional groups that would shift it to other subheadings.
Morpholine Industrial Grade
Morpholine is a six-membered heterocyclic ring with one oxygen and one nitrogen hetero-atom, but classified here due to oxygen hetero-atom specification. Used in rubber curing and corrosion inhibitors. HTS 2932.99.90 as other oxygen-containing heterocycles.
Epichlorohydrin (Pure)
Epichlorohydrin is a three-membered epoxide ring with oxygen hetero-atom and chloromethyl group, precursor for epoxy resins. Despite epoxide note exclusion, classified 2932.99.90 as halogenated oxygen heterocycle. Chapter notes distinguish from simple epoxides.
Diglyme (Diethylene Glycol Dimethyl Ether)
Diglyme is a heterocyclic diether with oxygen hetero-atoms in flexible ring conformation, used in organometallic chemistry. HTS 2932.99.90 as other oxygen heterocycles distinguished from acyclic ethers.
2-Methyltetrahydrofuran
2-Methyltetrahydrofuran (2-MeTHF) is a five-membered oxygen heterocyclic ring with methyl substitution, bio-based solvent alternative to THF. Classified HTS 2932.99.90 as substituted oxygen heterocycle.
Butyrolactam (2-Pyrrolidone)
2-Pyrrolidone contains oxygen in lactam structure (five-membered ring), used in pharmaceuticals and polymers. Dual O/N heteroatoms but oxygen heading applies. HTS 2932.99.90 classification.