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Heterocyclic compounds with oxygen hetero-atom(s) only: > Other: > Other: > Other
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Articles the product of any country, as provided for in subdivision (aa)(ii) of U.S. note 2 to this subchapter
Products classified 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.
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.
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.
Oxetane Monomer
Oxetane is a four-membered heterocyclic ring with one oxygen hetero-atom, used in polymer synthesis. Distinct from three-membered epoxides excluded by notes. HTS 2932.99.90 classification.
Tetrahydrofurfuryl Alcohol
Tetrahydrofurfuryl alcohol has furan ring with oxygen hetero-atom and hydroxymethyl substituent, used as solvent. Classified HTS 2932.99.90 as substituted oxygen heterocycle.
1,3,5-Trioxane Crystals
1,3,5-Trioxane forms six-membered ring with three oxygen hetero-atoms from formaldehyde cyclization. Used in polymers despite chapter note exclusion reference. HTS 2932.99.90 as defined oxygen heterocycle.
Methyloxirane (Propylene Oxide)
Propylene oxide is three-membered epoxide with methyl substitution and oxygen hetero-atom, epoxidation agent. Classified 2932.99.90 despite general epoxide exclusion due to substitution. Industrial chemical staple.
Dioxolane Solvent Grade
1,3-Dioxolane is a five-membered heterocyclic ring with two oxygen hetero-atoms, used as a solvent in polymer and adhesive industries. Classified under HTS 2932.99.90 as 'other' heterocyclic compounds with oxygen hetero-atoms only. Excluded from epoxides or other specific ring structures noted in Chapter 29.
1,4-Dioxane Laboratory Reagent
1,4-Dioxane is a six-membered heterocyclic ring with two oxygen hetero-atoms, commonly used as a solvent in labs and extractions. Falls under HTS 2932.99.90 as other heterocyclic compounds with oxygen only. Stabilized grades must meet Chapter 29 note (f) to remain classified here.
Tetrahydrofuran (THF) ACS Grade
Tetrahydrofuran (THF) is a five-membered heterocyclic ring containing one oxygen hetero-atom, used as solvent in Grignard reactions. HTS 2932.99.90 covers this as other oxygen heterocyclic not specified elsewhere. ACS grade ensures high purity meeting chemically defined compound criteria.
Gamma-Butyrolactone (GBL)
Gamma-butyrolactone is a five-membered lactone ring (cyclic ester) with oxygen hetero-atom, used as solvent and precursor. Falls under HTS 2932.99.90 as other oxygen heterocycles, distinguished from excluded cyclic esters of polyhydric alcohols.