Process for making tetramethyl lead

Tetramethyl lead is prepared by the reaction of a monosodium lead alloy with at least one mole of methyl chloride per mole of alloy at a temperature of from - 20 DEG to 120 DEG C. in the presence of from 0.01 to 1.5 moles of ammonia per mole of alloy. Advantageously there may also be present up to 0.04 moles of water per mole of alloy provided the amount of water does not exceed 0.3% by weight of the methyl chloride, and up to 0.04 moles per mole of alloy of a monohydroxylic organic compound ROH, wherein R is a hydrocarbon or oxahydrocarbon radical containing 1 to 18 carbon atoms. Preferably ROH is methanol. The methyl chloride may contain up to 5 mole per cent methyl iodide. The reactants may be introduced separately or together, all at once or gradually into the reaction vessel. The ammonia and co-catalyst components may be added as such or in a carrier which may be the methyl chloride or an inert solvent such as toluene or iso-octane which also acts as a thermal stabilizer. The ammonia may be gaseous or liquid. 1 to 5% of graphite may be present as a lubricant, and the reaction may take place under a pressure of 100-300 p.s.i.g. The product is recovered by conventional methods.