WCO Explanatory Notes reproduced for reference. © World Customs Organization. Verify against official WCO publication.
29.33 - Heterocyclic compounds with nitrogen heter+atom(s) only (+). - Compounds containing an unfused pyrazole ring (whether or not hydrogenated) in the structure : 2933.1 1 2933.19 - - Phenazone (antipyrin) and its derivatives - - Other -Compounds containing an unfused imidazole ring (whether or not hydrogenated) in the structure : 2933.2 1 2933.29 - - Hydantoin and its derivatives - - Other - Compounds containing an unfused hydrogenated) in the structure : 2933.33 - - Pyridine and its salts - - Piperidine and its salts - - Alfentanil (INN), 2933.39 - - Other 2933.3 1 2933.32 pyridine ring (whether or not brornazepam - Compounds containing in the structure a quinoline or isoquinoline ringsystem (whether or not hydrogenated), not further fused : 2933.41 2933.49 - - Levorphanol (INN) and its salts - - Other .- Compounds containing a pyrimidine ring (whether or not hydrogenated) or piperazine ring in the structure : 2933.52 - - Malonylurea (barbituric acid) and its salts 2933.53 - - Allobafbital (INN), arnobarbital (INN),barbital INN), butalbital (A), 2933.54 2933.55 \ butobarbital, c clobarbital (INN), methy phenobarbital pentobarbital phenpbarbital (INN), secbutabarbital secobarbital (INN) and vinylbital (INN); salts thereof - - Other derivatives of malonylurea (barbituric acid); salts thereof - - Loprazolam (INN), mecloqualone (INN), methaqualone (INN) and zipeprol (INN); salts thereof 2933.59 - - Other - Compounds containing an uifused triazine ring (whether or not hydrogenated) in the structure : 2933.61 2933.69 2933.71 2933.72 2933.79 2933.91 - - Melamine - - Other - Lactams : - - 6-Hexanelactam (epsilon-cap~.olactam) - - Clobazam (INN) and rnethyprylon (INN) - - Other lactams - Other : - - Alprazolam carna:sepam (INN), chlordiazepoxide INN , clonazepam m l c l o r a z e pate, delorazepam ( , d~azepam INN estazolam ethyl loflazepate (INN)~udiazepam [INN/: flurazepam (INN), halaze am (INN), lorazepam flunitrazepam (&, (INN), lormetazepam (TNPJ), mazindol (IN ), medazepam INN midazolarn (INN), nimt:taze am (INN), nitrazepam [INN]: nordazepam (INN), oxazepam pinazepam (INN), razepam (INN), pyrovalerone (INN), ternazeparn (INN), tetrazeparn PhN) and triazolam (INN);salts thereof (h) fi~), hP 2933.99 - - Other The heterocyclic compounds covered by this heading are : (A) Compounds containing an unfused pyrazale ring (whether or not hydrogenated) in the structure. This part includes, inter alia : a (1) Phenazone antipyrin, dimethylphenylpyrazolone). Crystalline powder or flakes, colourless, o ourless. Used in medicine as an anti-pyretic and anti-neuralgic agent. (2) Aminophenazone (4-dimethylamino-2,3-dimethyl-l-phenyl-5-pyrazolone) (amido~vrin. dimethvlaminoanalgesine) and its salts. CoIourIess. leaf-shawcd crystals: it has strongerwanti-pyretic&d a,&-neuralgicproperties than ana'lgesine. (B) Compounds containing an unfused imidazole ring (whether or not hydrogenated) in the structure. This part includes, inter alia (1) Hydantoin, and its substitutitrn derivatives (e.g,, nitrohydantoin, methylhydantoin and phenylhydantoin). Obtained by the condensation of gIycol1ic acid with urea. (2) Lysidine. Hygroscopic white crystals; used in medicine as a solvent for wric acid. (C) Compounds containing an unfused pyridine ring (whether or not hydrogenated) in the structure. This part includes, inter aliu (1) Pyridine. Contained in coal tar, in bone oil, etc. Colourless or faintly yellow liquid with a strong, disagreeable odour. Used in organic synthesis, in the rubber industry, in dyeing and printing textile fabrics, as a denaturant for alcohol, in medicine, etc. To fall in this heading, pyridine must have a purity of 95 % or more by weight. Pyridine of lower purity is excluded (heading 27.07). (2) Pyridine derivatives include, inter alia : (a) Methylpyridine (picoline), 5-ethyl-2-methylpyridine (5-ethyl-2-picoline) and 2vinylpyridine. To fall in this heading, these derivatives must have a purity of 90 % or more by the case of methyl yridine, all the methyl yndine isomers must be taken The derivatives of ower purity are exclu ed (heading 27.07). f' (b) Pyridine-carboxylic acids. These include pyridine-y-carboxylic acid (isonicotinic acid). Colourless crystals, formed by oxidation of y-picoline, or by synthesis. Its hydrazide is used in the treatment of tuberculosis. P 'dine-pcarboxylic acid, known 2E6). as nicotinic acid is, however, excluded (heading (c) Diethylamide of pyridine-a-carboxylic acid. Oily liquid, almost colourless; used in medicine for stimulating the circulation and respiration. (d) mesoInositol hexanicotinate. (3) Piperidine derivatives include : (a) 1-Methyl-4-phenylpiperidine carboxylic acid. (b) 1-Methyl-3-phenylpiperidine-3-carboxylic acid ethyl ester. (c) 1-Methyl-4-phenylpiperidine-4-carboxylicacid ethyl ester (gethidine). (d) Ketobemidone (INN) (I-14-(m-hydroxypheny1)-1-methyl-4-p-1one). (D) Compounds containing a quinoline or isoquinoline ring-system (whether or not hydrogenated), not further fused. comprisin a benzene ring coal tar, ut may also be refractive, with a characteristic (e.g., dyes, medicaments). % These derivatives include, inter aha : (1) Methylquinoline. (2) Isobutylquinoline. (3) Isopropylquinoline. (4) Tetrahydromethylquinoline. ( 5 ) 3-, 4-, 5-, 6-, 7- and 8-Hydroxyquinolines and their salts. Derived by introducing a hydroxyl group into either ring of the quinoline molecule. This group includes metal complex compounds of &hydroxyquinoline. (6) Phenyl uinolinecarboxylic acid (phen lcinchoninic acid). Colourless needles or yellowis -white powder. An anti-gout an anti-rheumatism remedy. R ‘I (7) Octaverine (INN) (6,7-dimethoxy- 1-(3,4,5-triethoxypheny1)isoquinoline). (E) Compounds containing a pyrimidine ring (whether or not hydrogenated) or piperazine ring in the structure. This part includes, inter alia : (2) Thiopentone sodium (penthiobarbital sodium), a cyclic thioureide. A yellowish-white water-soluble hygroscopic powder with an unpleasant odour. Used in medicine as an anaesthetic. (3) Pi erazine (diethylenediarnine). Crystalline white mass, hygroscopic, with an ingividual odour. Used in medicine as an anti-gout remedy. (4) 2,5-Dimethylpiperazine, Colourless oily liquid or paste, used as a solvent for uric acid. (F) Compounds containing an unfused triazine ring (whether or not hydrogenated) in the structure. This part includes, inter alia : (1) Melamine (triaminotriazine). Sparkling white crystals used in the manufacture of plastics. (2) Trimethylenetrinitramine (hexogen). An explosive, crystalline white powder, sensitive to shock. (3) Cyanuric acid (en01 and keto forms). (4) Methenamine (INN) (hexamethylenetetramine), its salts and derivatives. Regular shaped white crystals, ve soluble in water. Used in medicine as a solvent for uric acid (unnary antiseptic), for t e manufacture of synthetic resins, as an accelerator in the vulcanisation of rubber, as an anti-fermentation agent, etc. X This heading excludes pastilles and tablets of methenamine (INN) for medical uses 30.04) and methenamine put up in forms (for example, tablets, sticks or similar as fuels (heading 36.06). (G) Lactams. These com ounds may be regarded as internal amides analogous to lactones; obtained from mno-aci s by elimination of water. The molecules may contain one or more amide functions in a ring. They are known as mono-, di-, trilactams, etc., according to the number of arnide fmctions present. ~f' This heading also includes lactims, which are the enolic tautomers of lactams (these being the ketonic isomers). This part includes, inter alia : (1) 6-Hexanelactam (E-caprolactam).White crystals; soluble in water; gives off pungent fumes. Used in the manufacture of plastics and man-made fibres. (2) Isatin (lactam of isatic acid). Brilliant yellowish-brown crystals. Used for the preparation of dyestuffs and in medicine. (3) 2-Hydroxyquinoline (carbostyrile), a lactarn of o-arninocinnamic acid. heny1)oxindole (diacetyldihydroxydiphenylisatin). White crystalline powder, insolub e in water. Used as a laxative. (4) 3,3-Di@-aceto rP, (5) 1-Vinyl-2-pyrrolidone. Yellowish crystalline powder with a pleasant odour. Used for the preparation of poly(viny1 pyrrolidone) (classified in Chapter 39), and in medicine. (6) Primidone (INN) (5-ethyl-5-phenylperhydropyrirnidine-4,6-dione). White crystals; soluble in water. The heading does not include betaine (trimethylglycine, trimethylglycocoll), an intramolecular quaternary ammonium salt (heading 29.23). (H) Other heterocyclic compounds with nitrogen hetero-atom(s) only. This part includes, inter alia (1) Carbazole and its derivatives. Derived from the fusion of two benzene rin s with a yrrole nucleus. Found in heavy fi-actions of coal tar oil, and also obtained syn etically. &arkling crystalline flakes used in the manufacture of dyes and of plastics. f (2) Acridine and its derivatives. Acridine results fiom the condensation of two benzene rings with a pyridine ring. Small quantities are found in coal tar, but it may also be prepared by synthesis. Used for the preparation of dyestuffs and certain medicaments. The heading covers the following acridine derivatives (other than those constituting dyestuffs) : (a) Proflavine (3,6-diarninoacridinium hydrogen sulphate), reddish-brown crystalline powder. (b) Lactate of 2,5-diamino-7-ethoxyacridine, yellow powder. Both of these derivatives have antiseptic and germicidal properties. (3) Indole. Found in coal tar, but usually obtained by synthesis. Small crystalline leaves; colourless or very faintly yellow, turning red on ex osure to air or light. A pronounced faecal odour when impure, but smells stron ly of owers when pmfied. Used for the preparation of synthetic perfumes and in me icine. 8 R (4) PMethylindole (skatole). Crystallises in colourless flakes; a faecal odour when impure. (5) Mercaptobenziminazole. (6) Phthalhydrazide (hydrazide of phthalic acid). (7) Ethyleneimine (aziridine) and its N-substituted derivatives. (8) Porphyrins (derivatives of porphine). However, porphyrine (an alkaloid) is to be classified in heading 29.39. Certain substances of this heading, which are regarded as narcotic drugs or as psychotropic substances under international instruments, are indicated in the list appearing at the end of Chapter 29. This heading excludes imides of polybasic acids.
Subheading Explanatory Notes. Subheadings 2933.11,2933.21 and 2933.54 P h e m n e subheading 2933.11), hydantoin (subheading 2933.21) and barbituric acid (subheading 2 33.52) are products characterized by their heterocyclic structure. Derivatives of these products classified in their respective subheadings should also retain the basic structure of the parent compound. Thus, when compared to the parent compound, these derivatives generally : (a) have the functional groups (e.g., 0x0-group) unmodified; @) retain the number and position of double bonds; (c) retain the substituents (e.g., phenyl group and the two methyl groups of phenazone); and (d) have ver.substi@tions of hydrogen atoms only (e.g., a hydrogen atom in the pyrimidine ring of barbiturlc acld substituted by an alkyl group). However, salts obtained fiom the en01 form of a parent compound are to be regarded as derivatives of the keto form. Subheading 2933.79 Lactams containing an additional hetero-atom, other than the nitro en atom of a lactam oup (e dilactams), in the same ring should not be classified in the subhea g for lactams. In sucrcases, additional hetero-atom should be taken into account in determining the classification. Thus, for example, oxazepam (INN)should be classified in subheading 2933.91 and not in subheading 2933.79. & 8; If the amide function forms part of two or more rings and if one of these rings does not contain.an additional hetero-atom (other than the nitrogen of a lactam group), then the molecule should be considered as a lactam. To be classified in subheading 2933.79, lactams must have the different lactam groups separated b at least om carbon atom at each end. However, this subheading does not include those products in w&ch the carbon atoms separating and adjacent to the lactam groups form an 0x0 grou (>C=O), an imino group X = N H or a thioxo group (X=S). Thus, far example, barbituric aciB is excluded from subhe ng 293 .79 (subheading 2933.52). 6,
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.