WCO Explanatory Notes reproduced for reference. © World Customs Organization. Verify against official WCO publication.
28.12 - Halides and halide oxides of non-metals. 28 12.10 2812.90 - Chlorides and chloride oxides - Other (A) CHLORIDES OF NON-METALS The most important of these binary compounds are : (1) Iodine chlorides. (a) Iodine chloride (IC1) results fiom direct action of chlorine on iodine. Dark brown liquid above 27 "C;below that tem erature, reddish crystals. Specific gravity about 3. Decomposed by water; it bums %e skin badly. Used in organic synthesis as an iodinatmg agent. (b) Iodine trichloride (ICW. Obtained by the same hydriodic acid. Yellow needles soluble in water. same purposes as the monochloride and also in as the monochloride, or from gravity about 3. Used for the (2) Sulphur chlorides. (a) Disulphur dichloride (S2C12).Obtained by the action of chlorine on sul hur. This is the commercial sulphur chloride, a yellow or reddish liquid, fving fumes of a suffocatin odour when exposed to air; decomposed by water. pec~ficgravity about 1.7. A so vent for sulphur, it is used in the cold vulcanisatxon of rubber or of gutta-percha. f (b) Sulphur dichloride (SC12 . Prepared fiom monochloride. Reddish-brown li uid, also decomposed by water; ra er unstable. Specific gravity about 1.6. Uses inc ude : the B ? cold vulcanisation of rubber, as a chlorinating agent in the manufacture of synthetic dyes (in particular thioindigo). (3) Phosphorus chlorides. (a) Phosphorus trichloride @C13). Obtained by the direct action of chlorine on phosphorus. Colourless liquid, specific gravity about 1.6; corrosive, wth an irritate odour, ac?lFumes in a humid atmosphere,and decomposes on contact rn water. M y use as a chlorinating agent in orgmc synthesis (e.g, manufacture of acid chlorides, dyes, etc.); also used in the manufacture of cerarmcs to produce a lustrous effect. (b) Phosphorus pentachloride (PC&). Obtained from trichloride in the form of white or yellowish crystals. Specific gravity about 3.6. Like the trichloride, it fumes in a humid atmosphere; decomposes on contact with water and is lachrymatory. Used in organic chemistry as a chlonnating agent or a catalyst (e.g., to prepare isatin chloride). Phosphonium chloride (PhC1) is excluded (heading 28.53). (4) Arsenic chlorides. Arsenic trichloride (AsC13). Obtained by the action of chlorine on arsenic or of hydrochloric acid on arsenic trioxide. Colourless liquid of oily appearance. Fumes in moist air; very toxic. (5) Silicon chlorides. Silicon tetrachloride (Sic&). Obtained by the action of chlorine as on a mixture of silica and coal, or on silicon, silicon bronze or ferro-silicon. Colourless iquid, spectfic gravlty of about 1.5. Liberates suffocating white fumes (hydrogen chloride (HC1)) in the presence of atmospheric moisture. Decom oses in water with formation of gelatinous silica and liberation of HCl fumes. Use for preparing silica and very pure silicon, silicones and smoke screens. F Substitution roducts of hydrogen silicides, such as trichlarosilane (SiHC13) are excluded (heading 28.A). The headin does not include carbon tetrachloride hexachlonck,) (C2C16), hexachlombenzene (ISO) carbon chlorides; these are chlorinated derivatives (CCb) hexachloroethane (carbon (ClsCls) and similar (B) CHLORTDE OXIDES OF NON-METALS These ternary combinations include, inter alia : (1) Sulphur chloride oxides. (a) Sulphur dichloride oxide (sulphinyl chloride, thionyl chloride) (SOC12 . Obtained by the oxidation of sulphur dichloride with either sulphur trioxide or sulp uryl chloride. Colourless liquid; specific gravity about 1.7. Gives off suffocating vapours; decomposed by water. Used in the manufacture of organic chlorides. h (b) Sulphur dichloride dioxide (sulphonyl chloride, sul huryl chloride) (" dichloroObtained by the action o chlorine on sulphur dioxide presence of a catalyst (camphor or activated about 1.7. Fumes in the air; decomposed by and sulphonating agent in organic synthesis, e.g., in the manufacture of acid chlorides. ? The headin excludes chlorosulphuric acid (" sulphuric chlorohydrin") (CIS02.0H) (heading 28. 6). (2) Selenium dichloride oxide. Selenium dichloride oxide, generally called " selenyl chloride " (SeOC12) is similar to thionyl chloride. Produced by the action of selenium tetrachloride on selenium dioxide. Above 10 "C it is a yellow liquid, h i n g in the air; below that temperature it forms colourless c stals; s ecific gravity is about 2.4. Decomposed by water. Used in organic synthesis or or decar onising the cylinders of internal combustion engines. ! ?' (3) Nitrosyl chloride (nitrogen chloride oxide) (NOC1). Orange yellow gas with a suffocating smell; toxic; used as an oxidising agent. (4) Phosphorus trichloride oxide (phosphoryl chloride) (POC13). a Obtained from phos horus trichloride treated with potassium chlorate, fiom phosphorus pentachloride treate with boric acid, or by the action of carbonyl chloride on tricalcium phosphate. Colourless liquid, specific gravity about 1.7. It has an Irritating odour, fumes in a humid atrnos here and is decomposed by water. Used as a chlorinating agent in organic synthesis and a so in the manufacture of acetic anhydride or chlorosulphonic acid. P (5) Carbon chloride oxide (carbonyl chloride, phosgene) (COC12). Produced by the action of chlorine on carbon monoxide in the presence of animal black or charcoal, or by the action of oleurn on carbon tetrachloride. Colourless product, liquid up to 8 "C and gaseous above that tern erature; it is presented liquefied or under pressure in heavy steel containers. When ssolved in toluene or benzene, it is classified in heading 38.24. I A lachrymatory and very toxic product. It is a chlorinating a ent, widely used in organic synthesxs (e.g., in the manufacture of acid chlorides, amino erivatives, Michler's ketone and of intermediates in the organic dyestuff industry). B (C) OTHER HALIDES AND HALIDE OXIDES OF NON-METALS This group includes all other halides of non-metals (fluorides, bromides and iodides). (I) Fluorides. (a) Iodine pentafluoride (IF5), a fuming liquid. (b) Phosphorus fluorides and silicon fluorides. (c) Boron trifluoride (BF3). Obtained b heating natural calcium fluoride and powdered boric oxide in the presence of sulp uric acid. Colourless gas. Fumes in moist air; carbonises organic products. Highly absorbent of water forming fluoroboric acid. Used as a dehydrating agent h d as a catalyst in organic synthesis. It forms com lex compounds with organic compounds (e.g., diethy1 ether, acetic acid or phenol); gese compounds, which are also used as catalysts, fall in heading 29.42. K (2) Bromides. (a) Iodine bromide (monobromide) (IBr). Pr ared b combining the constituent elements. Blackish-red crystalline mass, resesling io&. Soluble in water. Used in organic synthesis. (b) Phosphorus bromides. Phos horus tribromide BQ). Obtained by the action of bromine on phosphorus disso ved in carbon disulp ide. Colourless liquid. Fumes in moist air; decomposes in water. Specific gravity about 2.8. Used in organic synthesis. P f' The heading excludes phosphonium bromide (pH&) (heading 28.53) and carbon bromides (heading 29.03). (3) Iodides. (a) Phosphorus iodides. Phos horus di-iodide (P&). Results fiom the action of iodine on phosphorus disso ved in carbon hsulphide. Orange-coloured crystals, giving off colouted vapour. 'f Phosphorus tri-iodide (PI3). Obtained by a similar method; crystallises into dark red tablets. Phosphoniurn iodide (PHJ) falls in heading 28.53. (b) Arsenic iodides. Arsenic tri-iodide (Ad3). Red crystals; obtained from the constituent elements. Toxic and volatile. Used in medicine or as a reagent in laboratories. (c) Combinations of iodine with other halogens. See paragraphs A (I), C (1) (a), C (2) (a) above. (4) Halide oxides other than chloride oxides. (a) Fluoride oxides, e.g., phosphorus trifluoride oxide (phosphoryl fluoride) (POF3). (b) Bromide oxides, e.g., sulphur dibromide oxide (thionyl bromide) (SOBr2), an orange-coloured liqu~d, and phosphorus hibromide oxide (phosphoryl bromide) (POBr3)in lamellar crystals. (c) Iodide oxides.
1.- Except where the context otherwise requires, the headings of this Chapter apply only to : (a) Separate chemical elements and separate chemically defined compounds, whether or not containing impurities; (b) The products mentioned in (a) above dissolved in water; (c) The products mentioned in (a) 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; (d) The products mentioned in (a), (b) or (c) above with an added stabiliser (including an anti-caking agent) necessary for their preservation or transport; (e) The products mentioned in (a), (b), (c) or (d) above with an added anti-dusting agent or a colouring substance 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.