WCO Explanatory Notes reproduced for reference. © World Customs Organization. Verify against official WCO publication.
29.32 Heterocyclic compounds with oxygen hetero-atom(s) only (+). - Compounds containing a n unfused furan ring (whether or not hydrogenated) in the structure : 2932.1 1 - - Tetrahydrofiran 2932.13 - - Furfiuyl alcohol and tetrahydrofurfury1alcohol - - Other - Lactones 2932.19 2932.20 - Other : 2932.91 - - Isosafiole 2932.93 - - Piperonal 2932.94 -- 2932.95 - - Tetrahydrocannabinols (all isomers) - - Other 2932.99 Safrole The heterocyclic compounds covered by this heading are : (A) Compounds containing an unfused furan ring (whether or not hydrogenated) in the structure. This part includes, inter alia : (1) Tetrahydrofuran. Colourless liquid. (2) 2-Furaldehyde (furfural). Prepared by distillin cereal bran with sul huric acid. Colourless llquid with a characteristic aromatic o our; it turns yellow an then brown when exposed to air. Used in the urification of mineral oils, for the preparation of synthetic resins, as a solvent for ce ulose nitrate and varnishes, as an insecticide, etc. K f B (3) Furfury1 alcohol. Colowless liquid which darkens when exposed to air. Reacts vigorously with concentrated mineral acids. Used as a solvent for cellulose nitrate, and for the preparation of varnishes and protective waterproof coatings. (4) Tetrahydrofurfuryl alcohol. Colourless liquid. (3) Lactones. These compounds may be considered as internal esters of carboxylic acids with alcohol or phenol function, formed by elimination of water. The molecules may contain one or more ester functions in a ring. They are known as mono-, di-, trilactones, etc., accordin to the number of ester funchons present. However, c clic esters of polyhydric alcoho s with polybasic acids are excluded (see Note 7 to this &apter). f Lactones are fairly stable compounds, but are characterized by the ease with which the lactone ring can be opened using an alkali. This part includes, inter alia : (a) Coumarin (1,Z-benzo yrone). This is the lactone of orthocoumaric acid. It crystallises in white fla es. It is used in perfumery, in medicine and for flavouring butter, castor oil, medicaments, etc. It also inhibits plant germination. E (b) Methylcoumarins. Same appearance as coumarin and also used in p e h e r y . (c) Ethylcoumarins. (d) Dicoumarol (dicoumarin). Crystals. Used in surgery as an anti-coagulant. (e) 7-Hydroxycoumarin (umbelliierone). White crystals. Absorbs ultra-violet rays, hence its use in suntan lotions and creams. (0 Dihydroxycoumarins (aesculetin and daphnetin). Crystals soluble in hot water. Glucosides of dihydroxycoumarins (aesculin and daphnin) fall in heading 29.38. (g) Nonalactone. Colourless or yellowish liquid; used in perfumery. (h) Undecalactone. Similar appearance and same uses as nonalactone. (ij) Butyrolactone (hydroxybutyric acid lactone). Colourless liquid with a pleasant odour; miscible wlth water. An intermediate product and solvent for synthetic resins. Used in preparations for removing paint stains, and in the petroleum industries. (k) Propionolactone. Liquid, soluble in water. A disinfectant, sterilising agent and germicide. (1) Glucuronolactone ( lucuronic acid lactone). White powder, very soluble in water. Used in medicine an as a growth factor. f (m) D-Gluconolactone (gluconic acid 8-lactone). Soluble crystals. Used in foodstuffs as an acidulant. (n) Pantolactone. Soluble crystals. Used to rectify pantothenic acid. (0) Santonin. This is the internal ester of santonic acid extracted from santonica, the dried unexpanded flower heads of Artemisia cina. Odourless, colourless crystals; a fairly energetic vermifuge (anthelmintic). (p) Phenolphthalein. Obtained b the condensation of phthalic anhydride with phenol. A white or ellowish-white, o ourless crystalline owder, soluble in ethanol. Reacts with alka is to give a cherry-red colour whicR disappears when the solution is acidified. Used as a chemical reagent and as a laxative. dY T This group includes iodophenolphthalein, a yellow powder, also used as a laxative. This heading, however, excludes : (i) Sodium derivatives of phthalein tetrahalides (heading 29.18). (ii) Fluorescein (resorcinol-phthalein) (heading 32.04). (q) Thymolphthalein. White crystals, used also as a reagent in analyses and in medicine. (r) Isoascorbic acid. Granular crystals. It should, however, be noted that this heading excludes ascorbic acid (heading 29.36). (s) Dehydracetic acid. Colourless crystals, insoluble in water. (t) Ambrettolide. Colourless liquid, musk-scented, used in perfumery. (u) Diketene. Colourless, non-hygroscopic liquid. (v) 3,6-Dimethyl-1,4-dioxane-2,5-dione. Other heterocyclic compounds with oxygen hetero-atom(s) only. This part includes, inter alia : (1) Benzofuran (coumarone). Found in light oils of the distillation of coal tar. A colourless liquid, used for the manufacture of artificial plastic materials (cournarone resins), etc. (3) 1,4-Dioxan (diethylene dioxide), used as a solvent. (5) Safrole. Obtained from sassafi-as oil. A colourless liquid which turns ellowish; used in perfumery and as a precursor for methylenedioxyamp etamine and methylenedioxyrnethamphetamine (see the list of precursors at the end of Chapter 29). h (6) Isosafrole. Obtained from safrole; used in perfumery and as a precursor for methylenedioxyam hetamine and methylene&oxymethamphetamine (see the list of precursors at the end o Chapter 29). P (7) Tetrahydrocannabinols. (8) Pi eronal (piperonylaldehyde or heliotropin) (CH202C6H3CHO). White crystals or f l z e s with an odour of hehotrope; used in perfumery and to flavour li ueurs and as a recursor for methylenedioxyam hetamine and methylenedioxymet amphetamine see the list of precursors at the en of Chapter 29). P S P (9) Piperonylic acid. (10) 1- 1,3-Benzodioxol-5-yl)propan-2-one (3,4-methylenedioxyphenylacetone).White to ye lowish crystals. Used as a precursor in the production of methylenedioxyamphetarnine and methylenedioxymethamphetamine (see the list of precursors at the end of Chapter 29). Hydromercuridibromofluorescein is to be classified in heading 28.52. Certain substances of this heading, which are regarded as narcotic drugs or as psychotropic substances under international instruments, are indicated in the list appeasing at the end of Chapter 29. This heading excludes : (a) Ketone peroxides (heading 29.09). (b) Epoxides with a three-membered ring (heading 29.10). (c) Cyclic polymers of aldehydes (heading 29.12) or of thioaldehydes (heading 29.30). (d) Anh drides of polybasic carboxylic acids and cyclic esters of polyhydric alcohols or phenols with polygasic acids (heading 29.17).
1.- Except where the context otherwise requires, the headings of this Chapter apply only to : (a) Separate chemically defined organic compounds, whether or not containing impurities; (b) Mixtures of two or more isomers of the same organic compound (whether or not containing impurities), except mixtures of acyclic hydrocarbon isomers (other than stereoisomers), whether or not saturated (Chapter 27); (c) The products of headings 29.36 to 29.39 or the sugar ethers, sugar acetals and sugar esters, and their salts, of heading 29.40, or the products of heading 29.41, whether or not chemically defined; (d) The products mentioned in (a), (b) or (c) above dissolved in water; (e) The products mentioned in (a), (b) or (c) above dissolved in other solvents provided that the solution constitutes a normal and necessary method of putting up these products adopted solely for reasons of safety or for transport and that the solvent does not render the product particularly suitable for specific use rather than for general use; (f) The products mentioned in (a), (b), (c), (d) or (e) above with an added stabiliser (including an anti- caking agent) necessary for their preservation or transport; (g) The products mentioned in (a), (b), (c), (d), (e) or (f) above with an added anti-dusting agent or a colouring or odoriferous substance or an emetic added to facilitate their identification or for safety reasons, provided that the additions do not render the product particularly suitable for specific use rather than for general use; (h) The following products, diluted to standard strengths, for the production of azo dyes : diazonium salts, couplers used for these salts and diazotisable amines and their salts. 2.- This Chapter does not cover : (a) Goods of heading 15.04 or crude glycerol of heading 15.20; (b) Ethyl alcohol (heading 22.07 or 22.08); (c) Methane or propane (heading 27.11); (d) The compounds of carbon mentioned in Note 2 to Chapter 28; (e) Immunological products of heading 30.02; (f) Urea (heading 31.02 or 31.05); (g) Colouring matter of vegetable or animal origin (heading 32.03), synthetic organic colouring matter, synthetic organic products of a kind used as fluorescent brightening agents or as luminophores (heading 32.04) or dyes or other colouring matter put up in forms or packings for retail sale (heading 32.12); (h) Enzymes (heading 35.07); (ij) Metaldehyde, hexamethylenetetramine or similar substances, put up in forms (for example, tablets, sticks or similar forms) for use as fuels, or liquid or liquefied-gas fuels in containers of a kind used for filling or refilling cigarette or similar lighters and of a capacity not exceeding 300 cm3 (heading 36.06); (k) Products put up as charges for fire-extinguishers or put up in fire-extinguishing grenades, of heading 38.13; ink removers put up in packings for retail sale, of heading 38.24; or (l) Optical elements, for example, of ethylenediamine tartrate (heading 90.01). 3.- Goods which could be included in two or more of the headings of this Chapter are to be classified in that one of those headings which occurs last in numerical order. 4.- In headings 29.04 to 29.06, 29.08 to 29.11 and 29.13 to 29.20, any reference to halogenated, sulphonated, nitrated or nitrosated derivatives includes a reference to compound derivatives, such as sulphohalogenated, nitrohalogenated, nitrosulphonated or nitrosulphohalogenated derivatives. Nitro or nitroso groups are not to be taken as “nitrogen-functions” for the purposes of heading 29.29. For the purposes of headings 29.11, 29.12, 29.14, 29.18 and 29.22, “oxygen function”, the characteristic organic oxygen-containing group of those respective headings, is restricted to the oxygen-functions referred to in headings 29.05 to 29.20.