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.
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More Specific Codes
This product may fall under a more specific subheading:
Alternative Classifications
This product could be classified differently depending on its characteristics or intended use.
If minimum 3-membered epoxide ring present
Epoxides specifically excluded from general heterocycle provisions.
If classified by carboxylic acid ester function
Lactones as cyclic esters may classify by oxygen function in 2918 per chapter notes.
If for retail as formulated cleaner
Consumer preparations containing GBL fall outside pure compound Chapter 29.
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Import Tips & Compliance
• DEA List I chemical; requires importer registration and advance notice per 21 CFR 1310
• Lactone structure verified by IR spectroscopy; distinguish from polymer grades
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.
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.