WCO Explanatory Notes reproduced for reference. © World Customs Organization. Verify against official WCO publication.
29.18 - Carboxylic acids with additional oxygen function and their anhydrides, halides, peroxides and peroxyacids; their halogenated, sulphonated, nitrated or nitrosated derivatives. - Carbox lic acids with alcohoI function but without other oxygen function, their an ydrides, halides, peroxides, peroxyacids and their derivatives : h - - Lactic acid, its salts and esters 2918.12 - - Tartaric acid 29 18.13 - - Salts and esters of tartaric acid 2918.14 - - Citric acid 2918.15 - - Salts and esters of citric acid 2918.16 - - Gluconic acid, its salts and esters 29 18.18 - - Chlorobenzilate (ISO) 2918.19 - - Other - Carbox lic acids with phenol function but 2918.11 without other oxygen function, their dYdrides,halides, peroxides, peroxyacids and their dmvatives : 291 8.21 - - Salicylic acid and its salts 29 18.22 - - 0-Acetylsalicylic acid, its salts and esters 2918.23 2918.29 2918.30 - - Other esters of salicylic acid and their salts - - Other - Carboxylic acids with aldehyde or ketone function but without other oxygen function, their anhydrides, halides, peroxides, peroxyacids and their derivatives - Other : 2918.91 2918.99 - - 2,4,5-T (ISO) (2,4,5-trichlorophenoxyaceticacid), its salts and esters - - Other This heading covers carboxylic acids with additional ox gen function and their anhydrides, halides, peroxides, eroxyacids, esters and salts, as we 1 as the halogenated, sul honated, nitrated or nitrosate derivatives (including compound derivatives) of any of these pro ucts. I' B The term "additional oxygen function" means carbox lic acids which contain also one or more of the oxygen functions referred to in previous sub- hapters (alcohol, ether, phenol, aldehyde, ketone, etc., functions). 6' (A) CARBOXYLIC ACIDS WITH ALCOHOL FUNCTION AND THEIR ESTERS, SALTS AND OTHER DERIVATWS These contain both the alcohol h c t i o n (-CH,OH, >CHOH or ~ C O H and ) the acid function (XOOH). These two functions may each react according to their own nature, hence as alcohols, these compounds may give ethers, esters and other derivatives, and as acids, they may form salts, esters, etc. The m a n alcohol acids include : (1) Lactic acid (CH3CH(OH)COOH). Pre ared by fermentin glucose or previously inverted cane-sugar with lactic ferment. Very ygroscopic crysta line masses, or a dense, s r p y liquid, colourless or faintly yellow. Used in medicine, for dyein and for deliming ides. This heading includes lactic acid whether industrial, cornrnercia or pharmaceutical. The industrial acid ranges from yellow to brown in colour and has a disagreeable, ve odour. The commercial or pharmaceutical acids usually contain 75 % or more o lachc acid. 7l B The main salts are calcium (used in medicine), strontium, magnesium, zinc, antimony, iron and bismuth lactates. Its esters include ethyl and butyl lactates, used as solvents for varnishes. Mercury lactate is excluded (heading 28.52). (2) Tartaric acid (HOOCCH(OH)CH(OH)COOH). Transparent colourless crystals. Used in dyeing, photography, manufacture of baking powder, in oenology and medicine. Its salts include : (a) Sodium tartrate. (b) Potassium tartrate. (c) Refined potassium hydrogen tartrate (cream of tartar). Crude tartar (Argol) is excluded (heading 23.07). (d) Calcium tartrate, small crystals. Crude calcium citrate is excluded (heading 38.24). (e) Antimony potassium tartrate (emetic), sodium potassium tartrate (sel de Seignette) and iron potassium tartrate. Its esters include : (i) Ethyl tartrates. (ii) Butyl tartrates. (iii)Pentyl tartrates. (3) Citric acid. Found in the free state of citrus h i t juices; also obtained from the fermentation of glucose or sucrose by some citromyces. Crystallises in large, colourless, transparent prisms or in crystalline, white, odourless powder. Used for preparing beverages, in the textile industry, in oenology, in medicine, in making citrates, etc. Its salts include : (a) Lithium citrate. (b) Calcium citrate. Crude calcium citrate is excluded (heading 38.24). (c) Aluminium citrate, used as a mordant in dyeing. (d) Iron citrate, used in photography. Its main esters are : (i) Triethyl citrate. (ii) Tributyl citrate. (4) Gluconic acid and its salts. Gluconic acid is normally presented as an aqueous solution. Its calcium salt is used e.g., in medicine, for cleaning and as a concrete additive. (5) Glueoheptonic acid and its salts, e.g., calcium glucoheptonate. (6) Phenylglycolic acid (mandelic acid). (7) Malic acid (HOOCCH(0 CH2COOH).Deliquescent, colourless, crystalline masses; used in organic synthesis, in me cine, etc. (B) CARBOXYLIC ACIDS WITH PHENOL FUNCTION AND THEIR ESTERS, SALTS AND OTHER DERIVATIVE3 I Phenol-acids, c clic (aromatic) acids which contain both the acid group -COOH) and one or more groups (4 3H) in the nucleus. The simplest phenol-acid has the formu a (HOCfiCOOH). (I) Salicylic acid (orthohydroxybenzoic acid) (HOC6H4COOH). Crystallises in white, voluminous flakes, or in white, light, odourless powder. Extens~velyused in medicine and also for preparing azo-dyes, etc. Its most important salts are : (a) Sodium salicylate. Crystalline powder or white, odourless flakes. Used in medicine. (b) Bismuth salicylate, an odomless, white powder, used in medicine. Its most important esters are (a) Methyl salicylate. Constituent of oil of wintergreen. An oily, colourless liquid with a strong persistent aromatic odour; used in medicme. (b) Phenyl salicylate (salol). Crystallises as colourless flakes with a faint, agreeable, aromatic odour. Used in medicine and as an antiseptic. (c) Ethyl, naphthyl, butyl, amyl, benzyl, bornyl, citronellyl, geranyl, menthyl, rhodinyl salicylates. (II) o-Acetylsalicylic acid (CH3C(0)OC6&COOH). Crystalline white powder; odourless; used in medicine. (In) Sulphosalicylic acid (salicylsulphonic acid). (IV) p-Hydroxybenzoic acid, crystalline. Its main esters include : (2) Ethyl p-hydroxybenzoate. (3) Propyl p-hydroxybenzoate. These esters are used as preservatives. (V) Cresotic acids. (VI) Acetyl-o-cresotic acids. (VII) Gallic acid ((H0)3C&2COOIF).Obtained from gall nuts. Fine, silky, shining colourless or faintly yellow, odourless crystals. Used for the preparation of dyes and inks, in photography, in tanning as a mordant, etc. Its main salts and esters include : (1) Basic bismuth gallate. An amorphous powder, lemon-yellow, odourless, a s h g e n t and absorbent; used in medicine. (2) Methyl gallate, crystals. Used as a disinfectant and astringent, and also in ophthalmology. (3) Propyl gallate. (VIIl) Hydroxynaphthoic acids. (IX) Hydroxyanthracenecarboxylic acids. (C) CARBOXYLIC ACIDS WITH ALDEHYDE OR KETONE FUNCTION AND THEIR ESTERS, SALTS AND OTHER DERIVATIVES (1) Aldehyde-acids contain both the aldehyde (-CHO) groupand the acid group (-COOH). (2) Ketone-acids contain both the ketone group (>C=O) and the acid group ( 4 0 0 H ) . The most important ester of these acids is ethyl aceto-acetate and its sodium derivative. (D) OTHER CARBOXYLIC ACIDS WITH ADDITIONAI, OXYGEN FUNCTION AND THEIR ESTERS, SALTS AND OTHER DEIUVATIVES Anisic acid (CH30C&14COOH).Obtained by oxidation of anisaldehyde, of methole and aniseed oil. Colourless crystals with a slight odour of anethole; used as an antiseptic, in medicine and in the manufacture of dyes. Sub-chapter VIII ESTERS OF INORGANIC ACIDS OF NON-METALS AND THEIR SALTS, AND THEIR HALOGENATED, SULPHONATED, NITRATED O R NITROSATED DERIVATIVES GENERAL (A) ESTERS OF INORGANIC ACIDS OF NON-METALS These compounds are usually formed by the reaction of an alcohol or phenol with inorganic acids of non-metals. The have the eneral formula (ROX) in which R is an alcohol~cor phenolic radical and X is X e residue ofthe inorganic acid molecule known as an acid radical. The acid radical of nitric acid is (-NO2), of sulphuric acid (=SO2), of phosphoric acid (=PO); and of carbonic acid (>CO). This sub-chapter excludes esters of later headings in this Chapter. (B) SALTS OF ESTERS OF INORGANIC ACIDS OF NON-METALS These can be obtained only fiom esters of inorganic polybasic acids of non-metals (sulphuric, phosphoric, silicic, etc.). Polybasic acids have more than one replaceable acidic element, and when all such elements are not esterified the result is an acid ester. Appropriate treatment of these acid esters produces a salt of an ester of an inorganic acid of a non-metal. Nitrous and nitric acids, on the other hand, being monobasic, can give only neutral esters.
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.