GB1041462A - Process and apparatus for the electrolytic reductive coupling of olefinic compounds - Google Patents

Abstract

In the electrolytic hydrodimerisation of an olefinic compound or the electrolytic reductive coupling of different olefinic compounds in an electrolyte in contact with the cathode of an electrolysis cell, an olefinic compound is used as solvent to extract the hydrodimerised or reduction coupled product from the electrolyte, the olefinic compounds being in the liquid phase under the conditions of electrolysis and extraction. Preferably the reactant olefinic compound or compounds should be used as the extracting solvent. Typically the electrolyte is an aqueous salt solution and should comprise cations which are not discharged at the voltages required for olefinic coupling. Suitable salts are amine and quaternary ammonium salts of a sulphonic or alkyl sulphuric acid which should be present in such concentration that they do not provide an electrolyte with which the olefinic compound is miscible. The olefinic compound should be present in at least 10% by weight of the aqueous salt solution and should form a supernatant layer over the electrolyte. In the case of 1:3-butadienes in solution only small amounts of water should be present since otherwise simple reduction may occur. In examples acrylonitrile is hydrodimerised to adiponitrile and the product is extracted with acrylonitrile either separately from or during the electrolysis. The cathode employed is a metal with a hydrogen over-voltage greater than that of copper. As shown the cell, e.g. of glass, contains a mercury cathode 5, electrolyte 6, supernatant layer of olefinic compound(s) up to level 15 of the overflow tube leading to a water wash vessel 16, from which a supernatant layer of olefinic compound and coupled product flows to a boiler 1 leading to a condeser 3 from which olefinic compounds is returned to the cell adjacent the cathode. The anode 10 is located in a chamber defined by a porous cup diaphragm, e.g. of unglazed porcelain, containing an aqueous acid or salt solution. A stirrer 13 and thermometer 11 are provided. <PICT:1041462/C6-C7/1>