Other

29.21 with methylamine of heading phenoxyacetic acid of headlng 29.18) ...................................................................................Heading 29.2 1 (3) Co-ordination compounds. Metal co-ordination compounds generally include all the types, whether or not charged, in which a metal is bound to several atoms (generally 2 to 9 atoms) made available by one or more ligands. The skeletal geometry formed by the metal and the atoms which are bound to it as well as the number of metal links are generally characteristic for a given metal. Co-ordination compounds, other than products classifiable in sub-chapter XI or in heading 29.41, should be considered as being fragmented by "cleavin of all metal bonds, apart from metal-carbon bonds, and should be classified according to t e fragment (regarded as a real compound for classification purposes) falling in Chapter 29, in the heading occurring last in numerical order. f For the urposes of Note 5 (C) (3) to this Chapter, the term "fragments" covers the ligands and the part&) containing the metalcarbon bond that have resulted fiom the cleavage. Examples are shown below : Potassium trioxalatoferrate (111) is classifiable in the headin in which the oxalic acid falls (heading 29-17), corresponding to the fragment obtained after c eaving of the metal bonds. k Ferrocholinate (D4T-T) is classifiable in the heading covering choline (heading 29.23), which is classified in the heading occuring last in numerical order, rather than in the heading for citric acid corresponding to the other fkagment that can be taken into account for classification purposes. Budotitane (INN) : After cleaving of the metal bonds, two fragments are obtained, one cones onding to ethanol (Chapter 22), the other to benzoylacetone (and its enol-function) classi led in heading 29.14. Budotitane (INN) should therefore be classified in heading 29.14. ? (4) Halides of carboxylic acids. Such halides are classified in the same headin as the correspondin acids. For example, isobutyryl chloride is classified (like the iso utyric acid to whi& it corresponds) in heading 29.15. % (H) Classification in headings 29.32,29.33 and 29.34 (Chapter Note 7) Headin s 29.32, 29.33 and 29.34 do not include e oxides with a three-membered ring, ketone peroxidpes, cyclic polymers of aldehydes or of thioa dehydes, anhydrides of polybasic carboxylic acids, cyclic esters of polyhydric alcohols or phenols with polybasic acids, or imides of olybasic acids, if the rin position hetero-atoms are those resulting solely from the cyclising Rnction or functions here fisted. P If, in addition to functions listed in the first sentence of Note 7 to Chapter 29, there are other ring-position hetero-atoms present in the structure, the classification should be carried out with reference to all the c clisin functions present. Thus, for exam le, anaxirone (INN) and pradefovir (INN) shou d be c assified in heading 29.34 as heterocyc ic compounds with two or more different hetero-atoms and not in heading 29.33 as heterocyclic compounds with nitrogen hetero-atoms only. r !? P N 0-' w Anaxirone (INN) Pradefovir (INN) (LT) Classification of derivatives The classification of derivatives of chemical compounds at heading level is to be determined by application of the General Interpretative Rules. Note 3 to this Chapter applies when a denvative is potentially classifiable in two or more headings. Within any one heading of this Chapter, derivatives are to be classified by application of SubheadingNote 1. (K) Fused ring systems A fused ring system is one in which there are at least two rings which have one, and only one, common bond and have two, and only two, atoms in common. Fused ring systems ap ear in the molecules of polycyclic compounds (e.g., polycyclic hydrocarbons, heterocyc/? ic corn ouncls) in which two cyclic rings are joined by a common side involving two adjacent atoms. Zamples are shown below : Naphthalene Quinoline Fused quinoline In complex ring systems, fusion can take place to more than one side of any particular ring. Polycyclic compounds in which two rings have two, and only two, atoms in common are said to be " ortho-fused ". On the other hand, polycyclic compounds in which one ring contains two, and only two, atoms in common with each of the two or more rings of a contiguous series of rings are said to be " ortho- and peri-fused ". These two different types of fused ring systems are illustrated by the following examples : 3 common faces 6 common atoms " Ortho-fused " system 7 common faces 8 common atoms 5 common faces 6 common atoms " Ortho- and peri-fused " systems On the other hand, the following is an example of a bridged (not fused) quinoline : Bridged quinoline. Sub-chapter I HYDROCARBONS AND THEIR HALOGENATED, SULPHONATED, NITRATED OR NITROSATED DERIVATIVES

Subheading Explanatory Note. Subheadings 2921.42 to 2921.49 Hydrocarbon derivatives of an aromatic monoamine are derivatives obtained by the substitution of one or both hydrogens of the amine nitro en only by an alkyl or cycloalkyl group. Substituents with one or more aromatic nuclei, whether or not l d e d to amme nitrogen by an alkyl chain, are therefore excluded. Thus, for example, xylidine should be classified in subheading 2921.49 as "Other" aromatic monoarnine and not as a derivative of aniline (subheading 2921.42) or of toluidine (subheading 292 1.43).