GB998024A - Electrolytic processes employing alkyl grignard electrolytes - Google Patents

Abstract

In an electrolytic process employing an alkyl Grignard electrolyte, heat produced during electrolysis is removed by circulating a coolant stream of alkyl halide in indirect heat exchange relationship with the electrolyte, the alkyl group of the alkyl halide coolant corresponding to the alkyl group of the alkyl Grignard reagent. Thus, should there be any leakage, the electrolyte and coolant will be non-reactive. The coolant is circulated through coils in the electrolytic cell and is itself cooled externally of the cell. In one example the coolant is maintained liquid throughout its circulation, Fig. 1 (not shown). As illustrated, in Fig. 2, the coolant acts as a vapour type refrigeration system. The coolant liquid vaporizes in the electrolytic cell under pressure controlled by a valve 32 and the vapour is then withdrawn and compressed at 34, cooled at 37 to condense it and the resultant liquid recycled through the cell. The controlled <PICT:0998024/C6-C7/1> pressure of the coolant vapour determines the temperature to which the electrolyte is cooled. The cooling coils may be finned and connected in parallel or series parallel arrangements. Consumable anodes are used, e.g. of Pb, which may be in the form of plates or Pb shot in foraminous baskets. The electrolyte comprises the alkyl Grignard reagent in a solvent including an ether or tertiary amine. It may also include an additional ether, e.g. tetrahydrofuran and benzene, toluene or xylenes for increasing electrolyte conductivity and excess alkyl halide to react with Mg plating out at the anode. In preparing (C2H5)4Pb the electrolysis was run at 20-100 DEG C., an anode and cathode current density of 0.2-100 A/foot2, 20-50 volts and higher and at a subatmospheric to low superatmospheric pressure, e.g. 60 p.s.i.g. Organometallic compounds of Zn, Al, Mg, Cd and Sn and (CH3)4Pb and (C2H5)4Pb are referred to as are also Grignard reagents having alkyl groups with 1-8 carbon atoms. Examples of alkyl halides which may be used with alkyl Grignard electrolytes having the same alkyl group are CH3Cl, CH3Br, C2H5Cl, C2H5I, n-C3H7Cl, n-C3H7Br and n-C4H9Cl. Specifications 839,172 and 882,005 are referred to.