Tetramethyllead synthesis

Electrochemical synthesis was utilized to prepare labeled compounds. Tetramethyllead labeled with 14C was prepared in a double compartment cell in DMF with NaClC>4, by electrolyzing 14CH3l on lead electrodes. The method is reported as superior to transmet-allation with methylmagnesium halide. It is also possible to incorporate lead isotopes. 2i°Pb2+ ions were deposited on a Cu foil and the latter was used as a sacrificial electrode in solutions of CH3I. The yield of labeled tetramethyllead was 85%65. Synthesis of 210Pb-labeled chlorotrimethylplumbane was also described66. 

Methyl chloride is used in the production of tetramethyllead antiknock compounds for gasoline and methyl silicone resins and polymers, and as a catalyst carrier in low-temperature polymerization (e g., butyl rubber), a refrigerant, a fluid for thermometric and thermostatic equipment, a methylating agent in organic synthesis, an extractant and low-temperature solvent, a herbicide, a topical antiseptic, and a slowing agent (lARC, 1986 Lewis, 1993). 

Note added in proof In May 1975 The and Cavell have reported (86b) the successful synthesis of dimethyltris(trifluoromethyl) and trimethylbis(trifluoromethyl) phospho-rane from the reaction of tetramethyllead with suitable fluorophosphorane precursors. The compounds are stable white solids of trigonal bipyramidal structure. 

As was mentioned in Section 1, the first synthesis of an organolead compound was reported by Lowig 210>211), who synthesized tetraethyllead by the reaction of a sodium-lead alloy with ethyl iodide. Some 35 years later, Polis 247,248) prepared the first aryl lead derivative by the reaction of bromobenzene with a sodium-lead alloy. Since 1923, the sodium-lead alloy-ethyl chloride reaction has been used for the commercial production of tetraethyllead. A similar reaction has also been used for the commercial production of tetramethyllead since 1960. The sodium-lead alloy-alkyl chloride reaction is discussed in Section 6. 

Of course, several totally new processes have been suggested for tetraethyllead, and especially, for tetramethyllead and methyl-containing mixtures. These processes are discussed under General Methods of Synthesis and "Tetramethyllead . 

Fig. 1. Flowsheet for the process of synthesis of tetramethyllead (TML) from lead-sodium alloy and methyl chloride (according to [117]).

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