GB749898A - Organic liquids having increased electrical conductivity - Google Patents

Abstract

The electrical conductivity of an organic liquid, as defined below, is increased by adding to the liquid, in minor proportions, (a) a polyvalent metal salt having a molecular weight of at least 200, and (b) a second additive, also having a molecular weight of at least 200, for which the product MC is at least 10-10, M being the molecular weight of the additive and C the electrical conductivity at 25 DEG C., expressed in reciprocal ohms per cm., of a solution of 1 gram of the additive in 1 litre of benzene; if the second additive is an electrolyte, its anion and cation must both be different from those of the first additive, and the proportions of the additives must be such that the electrical conductivity of the solution of the two additives in the organic liquid is at least five times the sum of the electrical conductivities, measured under the same conditions, of two separate solutions in the organic liquid, each solution containing one of the additives only in the same concentration as the solution of the two additives. The organic liquid is (a) a liquid organic compound having not more than 12 carbon atoms in the molecule and a dielectric constant below 8; or (b) a liquid mixture of two or more such organic compounds; or (c) a liquid mixture of such an organic compound or compounds with a minor proportion of other compounds, the average number of carbon atoms in the molecules of the mixture not exceeding 12 and the dielectric constant of the mixture being below 8. Specified organic liquids are aliphatic hydrocarbons or mixtures thereof, e.g. hexane, heptane, gasoline and kerosene, aromatic hydrocarbons or mixtures thereof, e.g. benzene, toluene and the xylenes, cycloaliphatic hydrocarbons, e.g. decalin, halogenated hydrocarbons or mixtures thereof, e.g. chloroform, carbon tetrachloride and tri- and tetrachlorethylene, and ethers, e.g. diethyl ether and dioxane. The additive (a) may be a salt of an alkaline-earth metal, magnesium, copper, zinc, cadmium, aluminium, lead, chromium, molybdenum, manganese, iron, cobalt, or nickel with a substituted or unsubstituted aliphatic, cycloaliphatic or aromatic mono- or poly-carboxylic acid, or with a phenol or an organic sulphonic acid. More particularly, the additive (a) may be a salt of a higher fatty acid, e.g. calcium or magnesium oleate, or a salt of a substituted higher fatty acid, e.g. calcium phenylstearate, or a salt of an alkylated aromatic carboxylic acid, e.g. of an alkylated salicylic acid such as di-isopropylsalicylic acid or an alkylsalicylic acid having 14-18 carbon atoms in the alkyl group, or a metal compound of an alkylphenolformaldehyde condensation product, or a salt of a sulphonated dialkyl ester of an aliphatic dicarboxylic acid, e.g. of dioctyl sulphosuccinate, or a salt of a petroleum sulphonic acid. The additive (b) may also be a polyvalent metal salt, provided that its anion and cation are both different from those of additive (a), or it may be an alkali-metal or ammonium salt or a salt of an organic base, e.g. a quaternary ammonium or phosphonium or ternary sulphonium salt, or an acid, a sulphone, a sulphonamide, a polyalkylene oxide, a phenol-formaldehyde condensation product, an alcohol, an ester, an ether, an oxidized mineral oil, a phosphatide or an asphaltene. The proportion of both additives (a) and (b) may be of the order of 10-7-10-4 mol. per litre. Experimental results are given showing that the electrical conductivity of each of the following solutions containing an additive (a) and (b) is at least five times the sum of the conductivities of separate solutions containing the same proportions of additive (a) only and additive (b) only: (1) benzene solutions containing, as additive (a), calcium, cupric, ferric, aluminium, chromic or magnesium diisopropylsalicylate, calcium phenylstearate, calcium or magnesium oleate, calcium or magnesium petroleum sulphonate or a mixture of calcium alkylsalicylates with 1-2 alkyl chains of 14-18 carbon atoms and, as additive (b), tetra-isoamyl ammonium picrate; (2) benzene solutions containing calcium di-isopropyl salicylate as additive (a) and, as additive (b), picric acid, tributyl ammonium picrate, sodium or chromium dioctyl sulphosuccinate, an octylphenol - formaldehyde condensation product, each of the substances sold under the Registered Trade Marks "Triton", "Igepal" and "Tween", a resin obtained in a described way by the air-oxidation of an acid-treated lubricating oil distillate, an asphaltene, lecithin, a polyethylene glycol stearate, polyethylene oxide or Dupont's additive PL 164; (3) benzene solutions containing, as additive (a), chromium diisopropylsalicylate and, as additive (b), sodium, lithium or ammonium dioctyl sulphosuccinate or sodium petroleum sulphonate; (4) benzene solutions containing chromium dioctyl sulphosuccinate or a mixture of calcium mono- and di-alkylsalicylates containing 14-18 carbon atoms in the alkyl group, respectively, as additive (a), and aluminium di-isopropylsalicylate or lecithin, respectively, as additive (b); (5) a solution in heptane of (a) chromium di-isopropylsalicylate and (b) sodium dioctyl sulphosuccinate; a solution in decalin of (a) chromium di-isopropylsalicylate and (b) lithium or ammonium dioctylsulphosuccinate; and a solution in dioxane, trichlorethylene or diethyl ether of (a) calcium di-isopropylsalicylate and (b) tetra-isoamyl ammonium picrate; (b) solutions of (a) calcium di-isopropylsalicylate and (b) tetra-isoamyl ammonium picrate in mixtures of benzene with various minor proportions of nitrobenzene. For purposes of comparison the electrical conductivities of solutions in benzene of the following substances are also recorded: (1) tetra-isoamyl ammonium picrate and ammonium di-isopropylsalicylate, oleic acid, ammonium oleate, a petroleum sulphonic acid, a sodium petroleum sulphonate, lithium dioctyl sulphosuccinate, cetyl pyridinium bromide, the resin used in Example 2, ethanol, 2-butoxyethanol, an asphaltene or a polyethylene glycol stearate; (2) calcium di-isopropylsalicylate and calcium petroleum sulphonate, di-isopropylsalicylic acid, hydroquinone dioctyl ether, mono-, di- or tri-ethanolamine or o-cresol; (3) chromium di-isopropylsalicylate and ammonium di-isopropylsalicylate, ethanol, 2-butoxyethanol or hexylene glycol; (4) sodium dioctyl sulphosuccinate and ammonium di-isopropylsalicylate; chromium and sodium dioctyl sulphosuccinates; calcium petroleum sulphonate and the calcium compound of an octylphenol-formaldehyde condensation product; chromium and ammonium di-isopropylsalicylates; sodium petroleum sulphonate and the resin used in Example 2; and calcium phenylstearate and oleic acid. The increased conductivity of the organic liquids reduces the electrostatic charge, and therefore the risk of fire or explosion, which may develop during the transportation of the liquids or in processes in which the liquids are used, e.g. dry-cleaning processes or processes in which the liquids are separated from solids by centrifuging. The Specification adverts also to prior proposals in which the same end was sought to be achieved by adding to the liquids (1) a polyvalent metal soap, e.g. magnesium oleate; (2) an ammonium salt of a fatty acid substituted on the nitrogen atom by at least one alkyl, substituted alkyl, phenyl or benzyl group, e.g. triethyl ammonium oleate; (3) an alkali or alkaline-earth metal or ammonium salt of an organic sulphonic acid or acid sulphuric ester; or (4) a quaternary ammonium or phosphonium salt, or a ternary sulphonium salt, containing an aliphatic chain of 8-22 carbon atoms.ALSO:The electrical conductivity of an organic liquid, as defined below, is increased by adding to the liquid, in minor proportions, (a) a polyvalent metal salt having a molecular weight of at least 200 and (b) a second additive, also having a molecular weight of at least 200, for which the product MC is at least 10-10, M being the molecular weight of the additive and C the electrical conductivity at 25 DEG C., expressed in reciprocal ohms per cm., of a solution of 1 gram of the additive in 1 litre of benzene; if the second additive is an electrolyte, its anion and cation must both be different from those of the first additive, and the proportions of the additives must be such that the electrical conductivity of the solution of the two additives in the organic liquid is at least five times the sum of the electrical conductivities, measured under the same conditions, of two separate solutions in the organic liquid, each solution containing one of the additives only in the same concentration as the solution of the two additives. The organic liquid is (a) a liquid organic compound having not more than 12 carbon atoms in the molecule and a dielectric constant below 8, or (b) a liquid mixture of two or more such organic compounds or (c) a liquid mixture of such an organic compound or compounds with a minor proportion of other compounds, the average number of carbon atoms in the molecules of the mixture not exceeding 12 and the dielectric constant of the mixture being below 8. Specified organic liquids are aliphatic hydrocarbons or mixtures thereof, e.g. hexane, heptane, gasoline and kerosine, aromatic hydrocarbons or mixtures thereof, e.g. benzene, toluene and the xylenes, cycloaliphatic hydrocarbons, e.g. decalin, halogenated hydrocarbons or mixtures thereof, e.g. chloroform, carbon tetrachloride and tri-and tetra-chlorethylene and ethers e.g. diethyl ether and dioxane. The additive (a) may be a salt of an alkaline-earth metal, magnesium, copper, zinc, cadmium, aluminium, lead, chromium, molybdenum, manganese, iron, cobalt or nickel with a substituted or unsubstituted aliphatic, cycloaliphatic or aromatic mono- or polycarboxylic acid or with a phenol or an organic sulphonic acid. More particularly, the additive (a) may be a salt of a higher fatty acid, e.g. calcium