WCO Explanatory Notes reproduced for reference. © World Customs Organization. Verify against official WCO publication.
29.29 - Compounds with other nitrogen function. 2929.10 - Isocyanates 2929.90 - Other This heading includes : (1) Isocyanates This grou of chemicals includes mono- and polyfunctional isocyanates. Isocyanates with di- or hig er functionality, such as methylene d~phenylisocyanate (MDI), hexamethylene diisocyanate (HDI), toluene diisocyanate (TDI) and toluene diisocyanate dimer, are used extensively in the manufacture of polyurethanes. R This headin excludes poly(methy1ene phenyl isocyanate) (crude MDI or polymeric MDI) (heading 3999). (2) Isocyanides (carbylamines). (3) Azides of carboxylic acids. (4) Or anic-substituted amide derivatives of inorganic acids (other than carbonic acid) an organic-substituted h i d e derivatives of inorganic acids. d (5) Calcium cyclamate (calcium cyclohexylsulpharnate). (6) Octamethylpyrophosphoramide(OMPA). (7) Dimethylnitrosamine. (8) Methyltrinitrophenylnitramine (tetryl), etc. Used as an explosive. (9) Nitroguanidine. Explosive. Sub-chapter X ORGANO-INORGANIC COMPOUNDS, HETEROCYCLIC COMPOUNDS, NUCLEIC ACIDS AND THEIR SALTS, AND SULPHONAMIDES GENERAL The organo-inorganic compounds covered by headin s 29.30 and 29.3 1 are organic com ounds whose molecules contain, in addition to atoms of hy ogen, oxygen or nitro en, those o metals or other non-metals (such as sulphur, arsenic, lead, von, etc.) directly linke to carbon. f t P Heading 29.30 (organo-sulphur compounds) and heading 29.31 (other organo-inorganic compounds) do not include sulphonated or halogenated derivatives (includng com ound derivatives) which, apart £torn hydro en, oxygen and nitrogen, only have directly l d e d to carbon the atoms of sul hur or of ha ogens which give them their nature of sulphonated or halogenated derivatives compound derivatives). $ Headings 29.32 to 29.34 cover heterocyclic compounds. The term "heterocyclic" refers to organic compounds composed of one or more rings, and which contain in the ring(s), in addition to the carbon atoms, atoms of other elements such as oxygen, nitrogen or sulphur. In this way, the following heterocyclic groups are derived : (A) FIVE-MEMBERED RINGS (1) Containing one hetero-atom : (a) Of oxygen : Furan group (heading 29.32). (b) Of sulphur : Thiophen group (heading 29.34). (c) Of nitrogen : Pyrrole group (heading 29.33). (2) Containing two hetero-atoms : (a) One oxygen, one nitrogen : Oxazole and isoxazole groups (heading 29.34). (b) One sulphur, one nitrogen : Thiazole group (heading 29.34). (c) Two nitrogen : Imidazole and pyrazole groups (heading 29.33). (3) Containing three or more hetero-atoms : (a) One oxygen, two nitrogen : Furazan group (heading 29.34). (b) Three nitrogen : Triazole group (heading 29.33). (c) Four nitrogen : Tetrazole group @eading 29.33). (B) SIX-MEMBERED RINGS (1) Containing one hetero-atom : (a) Of oxygen : Pyran group (heading 29.32). (b) Of sulphur : Thiin (Thiapyran) group (heading 29.34). (c) Of nitrogen : Pyridine group (heading 29.33). (2) Containing two hetero-atoms : (a) One oxygen, one nitrogen : Oxazine group (heading 29.34). @) One sulphur, one nitrogen : Thiazine group (heading 29.34). (c) Two nitrogen :Pyridazhe, pyrimidine, pyrazine and piperazine groups (heading 29.33). (C) OTHER MORE COMPLEX HETEROCYCLIC COMPOUNDS These result from the condensation of five- or six-membered heterocyclic compounds with other carbocyclic rings. Examples include the following groups : (a) Coumarone (heading 29.32). (b) Benzopyran (heading 29.32). (c) Xanthene (heading 29.32). (d) Indole (heading 29.33). (e) Quinoline and isoquinoline (heading 29.33). (f) Acridine (heading 29.33). (g) Benzothiophene (Thionaphthene) (heading 29.34). (h) Indazole (heading 29.33). (ij) Benzimidazole (heading 29.33). (k) Phenazine (heading 29.33). (1) Phenoxazine (heading 29.34). (m) Benzoxazole (heading 29.34). (n) Carbazole (heading 29.33). (0) Quinazoline (heading 29.33). (p) Benzothiazole (heading 29.34). For the purposes of headin s 29.32 to 29.34, with respect to one heterocyclic rin ,if on y one of the heterocyclic rings is within headings 2 .32 to 29.34, the compound should However, if two or more of the heterocyclic rings are level, the compound should be classified in the specific order. f !f
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.