Methyllead tetra

THE EFFECT OF IODIDE ION CONCENTRATION ON THE RATE OF IODINOLYSIS OF TETRA-METHYLLEAD IN SOLVENT ACETONITRILE... 

Salooja 269> has indicated that formaldehyde is a promoter of lead monoxide effectiveness. He attributes the antiknock superiority of tetra-methyllead over tetraethyllead to the greater formation of formaldehyde as well as its greater thermal stability. 

Outside of the antiknock field, the commercial applications of organolead compounds are relatively few and quite small. The largest of these applications is in the manufacture of organomercury fungicides by alkylation. This application is old and is relatively static. Other alkylations consume a little tetraalkyllead compound. A small amount of tetra-methyllead has long been used to fill Geiger counters. 

A limiting factor in the preparation of methylcopper from tetra-methyllead in alcoholic solution was the methanolysis reported by Costa et al. 78, 81) to occur above — 50°C by a homolytic mechanism,... 

Other organometallic initiators which have been mentioned include tetra-methyllead (or tetramethyltin) in ter/-butanol dispersed in an aqueous solution of ammonium persulfate and borax [64] and silver compounds such as silver nitrate with organic lead or tin compounds and organic promoters such as acetone, dimethyl sulfoxide, ethanol, or fert-butanol [65]. 

In Britain almost all of the tetraaUcyllead petrol additive is used in the form of tetramethyUead or tetraethyllead with little usage of the mixed alkyl compounds, whilst in the US rather more of the mixed alkyls are in use. Tetra-methyllead is more thermally stable, and generally less chemically reactive than tetraethyllead and European observations indicate that the former compound predominates in the atmosphere [17]. 

An additional feature of such transformations is the more effective use of the RX compoimd or the use of a lesser quantity of the RLi or RMgX compound. Incidentally, overheating of the Me3Tl induces violent detonation. As mentioned elsewhere in connection with free alkyl radicals and with thermal stabilities, other methyl metallic compounds such as tetra-methyllead, methylcopper, and dimethylcadmium decompose explosively if overheated. 

The recovery of the five alkylated lead from fish tissue averaged 74%. The reproducibility of the procedure was evaluated by analyzing 11 replicates of a fish homogenate, 1 g, each spiked with 5 yg of tetra methyllead. The coefficient of variation was 7.3%. 

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