Patent GB-842090-A (GB)
Title: Manufacture of hydrocarbon lead compounds by an electrolytic process
IPC: C25B3/13
Filed: 1956-06-07
Abstract: 842,090. Electrolytic production of hydrocarbon lead compounds and of aluminium. ETHYL CORPORATION. June 7,1956 [June 7, 1955(6) June 29, 1955, Aug. 18, 1955(5)], No. 17607/56. Class 41. Hydrocarbon lead compounds are produced by passing current through a lead anode and an electrolyte containing an organoaluminium compound. Examples of lead compounds formed by the process are tetraethyl-, tetraisopropyl-, tetrabutyl-, tetra (phenylethyl)-, triethylpropyl-, and ethyl triphenyl-lead. Typically the organoaluminium compound is triethyl aluminium which is either dissolved in an organic solvent when electrolysis is carried out at say 25 C. or is complexed with an alkali metal salt, e.g. sodium fluoride when a temperature of 80C. is used. Suitable solvents are dimethyl, diethyl and methyl ethyl and methyl n-propyl ethers and mixtures of these ethers ; ethylene glycol diethers such as the dimethyl, diethyl, methyl ethyl, methyl butyl and butyl lauryl ethers ; diethylene glycol ethers such as the dimethyl, ethyl butyl, and butyl lauryl ethers ; trimethylene glycol ethers such as the methyl ethyl ether ; glycerol ethers such as the trimethyl, dimethyl ethyl and methyl diethyl ethers ; cyclic ethers such as dioxane and tetrahydrofuran ; primary and secondary amines such as methyl amine and dimethyl amine and tertiary amines such as trimethyl amine, triisopropylamine, dimethyl ethyl amine, tetramethyl ethylene diamine, and N-methyl morpholine ; organometallic compounds other than those used as reactants, e.g. diethyl zinc; amides, e.g. formamide, and substituted amides; and hydrocarbons such as pentane, hexane, toluene, xylene, napthalene, and cyclohexane. With the use of thermal stabilizers such as naphthalene, styrene, azobenzene and furfural higher temperatures e.g. up to 200C. can be used. Ionizable compounds may be added to the electrolyte to increase its conductivity, e.g. chlorides, bromides, fluorides, or hydrides of alkali metals and alkaline earth metals, alkyl metal hydrides, mixed hydrides such as lithium aluminium hydrides, or sulphates. The organoaluminium compound may be an alkyl, an alkyl hydride or an alkyl halide or mixtures thereof. An aluminium alkyl may be replenished by reacting the aluminium cations at the cathode with hydrogen to form an aluminium hydride or an alkyl aluminium hydride with is then reacted either in situ or after removal from the cell with an α-olefine to reform an alkyl aluminium compound. Mixed compounds may be formed by using mixed α -olefines. The anode may be of pure lead or alloys, e.g. with tin, bismuth, cadmium, platinum or palladium, which reduce the overvoltage of the cell and may reduce dimerization or disproportionation reactions while not reacting to form organometallic compounds, or even of alloys with sodium, lithium, magnesium or zinc in some cases, or may be of conductive material, e.g. graphite, coated or impreganted with lead. The cathode on which aluminium is deposited simultaneously with the anodic formation of the hydrocarbon lead compound may be of lead or a material which does not alloy with aluminium such as platinum or graphite. A current density not greater than 25 amps./sq. dm is used and the reaction may be performed at atmospheric pressure, at pressures up to 100 atmospheres, or even at subatmospheric pressure. An inert gas atmosphere may be employed.