This heading covers saturated acyclic monocarboxylic acids and their anhydrides, halides, peroxides and peroxyacids, esters and salts, as well as the halogenated, sulphonated, nitrated or nitrosated derivatives (including compound derivatives) of any of these products.
(¥°) Formic acid (HCOOH) and its salts and esters. (a) Formic acid is found in nature and obtained synthetically. A mobile, colourless liquid, giving off slight fumes when exposed to air; has an irritating odour and is caustic. Used in dyeing, in tanning, in the coagulation of latex, in medicine as an antiseptic, or in organic synthesis. (b) The main salts of formic acid are : (1) Sodium formate (HCOONa). Deliquescent crystalline white powder; used in medicine, in tanning and in organic synthesis. (2) Calcium formate ((HCOO)2Ca). Crystals. (3) Aluminium formate ((HCOO)3Al). White powder used in the textile industry as a mordant and for waterproofing. There is also a basic formate usually put up in aqueous solution. (4) Nickel formate ((HCOO)2Ni). Used as a catalyst for the hydrogenation of oil. (c) The main esters of formic acid are : (1) Methyl formate (HCOOCH3). A colourless liquid with an agreeable odour. (2) Ethyl formate (HCOOC2H5). A colourless, mobile, volatile and inflammable liquid with an odour of rum. (3) Benzyl, bornyl, citronellyl, geranyl, isobornyl, linalyl, menthyl, phenylethyl, rhodinyl and terpenyl formates. Mainly used in perfumery. (¥±) Acetic acid (CH3COOH) and its salts and esters. (a) Acetic acid is obtained by the dry distillation of wood, or synthetically. A very acid liquid with a characteristic and penetrating odour of vinegar caustic. When cold it solidifies into colourless crystals (glacial acetic acid). A solvent for phosphorus and sulphur and for many organic substances. Commercial acetic acid is slightly yellowish in colour, and has very often a slight empyreumatic odour. Used in the textile industry, in tanning, as a coagulant for latex, or for the manufacture of acetates, synthetic plasticisers, pharmaceutical products, etc. (b) The main salts of acetic acid are : (1) Sodium acetate (CH3COONa). Colourless and odourless crystals, or anhydrous white or faintly yellow powder. Used as a mordant and for many chemical preparations. (2) Cobalt acetate ((CH3COO)2Co). Deliquescent violet-red crystals with an odour of acetic acid. (3) Calcium acetate ((CH3COO)2Ca). Colourless crystals when pure. (4) Basic copper acetate (CH3COOCuOH). Needles or small crystalline flakes, blue in colour; disintegrates on contact with air and turns greenish. (5) Neutral copper acetate ((CH3COO)2Cu). Greenish-blue powder or small crystals; disintegrates on contact with air and turns to a whitish powder (6) Lead acetate, neutral ((CH3COO)2Pb), or basic (e.g., Pb(CH3COO)2. 3PbO.H2O). The neutral acetate occurs as colourless or faintly yellow or blue, toxic crystals. The basic acetate is a dense, white powder, used in medicine and as a reagent for chemical analyses. (7) Lithium and potassium acetates, used in medicine; chromium, aluminium and iron acetates, used as mordants. (c) The main esters of acetic acid are : (1) Methyl acetate (CH3COOCH3). Found amongst the products of the dry distillation of wood. A liquid with a fruity odour; used for preparing artificial fruit essences, and as a solvent for fats, resins and cellulose nitrate, etc. (2) Ethyl acetate (CH3COOC2H5). Colourless, very mobile, highly inflammable liquid with a fruity odour; it may contain ethanol as an impurity. Used as a solvent for cellulose nitrate, varnishes, etc.; also in medicine as an antispasmodic and analgesic. (3) Vinyl acetate (CH3COOCH=CH2). Colourless liquid with a characteristic odour; a monomer used for preparing poly(vinyl acetate) (polymers of heading 39.05). (4) n-Propyl and isopropyl acetates. Used for making artificial fruit essences. (5) n-Butyl acetate. Colourless liquid; used for making artificial fruit essences and as a solvent. (6) Isobutyl acetate. Colourless liquid; used for making artificial fruit essences and as a solvent. (7) n-Pentyl acetate (n-amyl acetate) and 3-methylbutyl acetate (iso-amyl acetate). Used for making artificial fruit essences. (8) 2-Ethoxyethyl acetate. (9) Benzyl, terpenyl, linalyl, geranyl, citronellyl, anisyl, paratolyl, cinnamyl, phenylethyl, bornyl and isobornyl acetates. All used in perfumery. (10) Glycerol acetates (mono-, di-, triacetin). Theheading also includes acetic anhydride ((CH3CO)2O). Colourless liquid with a strong, irritating odour; caustic; used for chemical syntheses. (¥²) Mono-, di- and trichloroacetic acids and their salts and esters. (a) Monochloroacetic acid (ClCH2COOH). Colourless crystals. (b) Dichloroacetic acid (Cl2CHCOOH). Colourless liquid. (c) Trichloroacetic acid (Cl3CCOOH). Colourless crystals with penetrating odour; used in organic synthesis and in medicine. (¥³) Propionic acid (CH3CH2COOH) and its salts and esters. Propionic acid is a liquid with an odour similar to acetic acid. (¥´) Butanoic acids and their salts and esters. (a) Butyric acid (butanoic acid) is a dense, oily liquid with a disagreeable rancid odour; colourless. Used for deliming hides. (b) Isobutyric acid (2-methylpropanoic acid). (¥µ) Pentanoic acids and their salts and esters. (a) Valeric acid (pentanoic acid) is a colourless, transparent oily liquid with a disagreeable rancid odour. (b) Isovaleric acid (3-methylbutanoic acid). (c) Pivalic acid (2,2-dimethylpropanoic acid). (d) 2-Methylbutanoic acid. (¥¶) Palmitic acid (CH3(CH2)14COOH) and its salts and esters. (a) Palmitic acid is found in fats as a glyceride; it is a white powder, shiny crystals or colourless flakes. (b) Its main salts are : (1) Calcium palmitate, used in perfumery. (2) Aluminium palmitate, used for water-proofing textiles and for thickening lubricating oils. The water-soluble palmitic salts (e.g., sodium, potassium and ammonium palmitates) are soaps but they remain classified in this heading. (¥·) Stearic acid (CH3(CH2)16COOH) and its salts and esters. (a) Stearic acid is found in fats as a glyceride; white, amorphous, and similar to wax. (b) Its main salts are : (1) Calcium stearate, used in water-proofing textiles. (2) Magnesium stearate, used in the manufacture of varnishes. (3) Zinc stearate, used in medicine, in the rubber and plastics industries, and in the manufacture of oil-cloth. (4) Aluminium stearate, used for the same purposes as aluminium palmitate. (5) Copper stearate, used for bronzing plaster and as an antifouling agent. (6) Lead stearate, used as a drier. The water-soluble stearic salts (e.g., sodium, potassium and ammonium stearates) are soaps but they remain classified in this heading. (c) The esters also include ethyl and butyl stearates (used as plasticisers), and glycol stearate (used as a substitute for natural wax). (¥¸) Other products of this heading include : (a) Ethyl chloroformate, sometimes called ethyl chlorocarbonate - a colourless, lachrymatory liquid with a suffocating odour; inflammable. Used in organic synthesis. (b) Acetyl chloride (CH3COCl). Colourless liquid; when exposed to air gives off fumes irritating to the eyes; it has a strong odour. (c) Acetyl bromide (CH3COBr). Same characteristics as the chloride; used in organic synthesis. (d) Mono-, di- and tribromoacetic acids and their salts and esters. (e) n-Hexoic (caproic) and 2-ethylbutyric acids and their salts and esters. (f) n-Octoic (caprylic) and 2-ethylhexoic acids and their salts and esters. This heading excludes : (a) Potable solutions of acetic acid in water containing 10 % or less by weight of acetic acid (heading 22.09). (b) Salts and esters of crude stearic acid (generally heading 34.01, 34.04 or 38.24). (c) Mixtures of glycerol mono-, di- and tristearates, fat emulsifiers (heading 34.04 when they have the character of artificial waxes or heading 38.24 in other cases). (d) Fatty acids of a purity of less than 90 % (calculated on the weight of the dry product) (heading 38.23).
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