Alkyl lead

The lead alkyls inhibit auto-ignition which, by intermediary of lead oxide, PbO, increases the resistance to knocking. 

The lead alkyls and scavengers contained in fuels cause rapid poisoning ol exhaust gas catalytic converters. They are tolerated only in trace quantities in fuels for vehicles having that equipment. The officially allowed content is 0.013 g Pb/1, but the contents observed in actual practice are less than 0.005 g Pb/1. 

Lead, inorganic dusts and fumes, as Pb lead alkyls... 

Class 6 Poisons such as acetone cyanohydrin, acetonitrile, acrylonitrile, allyl alcohol, allyl chloride, airiline, epiclilorohydrin, lead alkyls, organophosphorus compounds. 

Indeed a detailed kinetic investigation of the reduction of alkyl iodides at a lead electrode in dimethylformamide shows that the process is complex and involves catalysis by a lead alkyl species at the surface (Fleischmann et al., 1971a). The catalytic cycle proposed was... 

Organic Lead. Alkyl lead compounds are actively metabolized in the liver by oxidative dealkylation catalyzed by cytochrome P-450. 

The primary source of lead in the environment has historically been anthropogenic emissions to the atmosphere. In 1984, combustion of leaded gasoline was responsible for approximately 90% of all anthropogenic lead emissions. EPA phased out the use of lead alkyls in gasoline, however, and by 1990, auto emissions accounted for only 33% of the annual lead emissions (EPA 1996h). Use of lead additives in motor fuels was totally banned after December 31, 1995 (EPA 1996f). The ban went into effect on February 2, 1996. Atmospheric deposition is the largest source of lead found in soils. Lead is transferred... 

Mansell RS, Ou L, Rhue RD, et al. 1995. The fate behavior of lead alkyls in the subsurface environment. Air Force Material Command. Tyndall Air Force Base, Florida. Armstrong Laboratory Report AL/EQ-TR-1994-0026. 

Partially alkylated lead alkyls R3PbCl and R2Pb(OAc)2, which are stabilized by having (CH3)3SiCH2 as R, appear to be reduced on Hg (in CH3OH) as follows ... 

Aquatic life in proximity to mining activities, lead arsenate pesticides, metal finishing industries, lead alkyl production, and lead aerosol fallout... 

Major sources of lead in Atlantic coast streams included wastes from metal-finishing industries, brass manufacturing, lead alkyl production, primary and secondary lead smelting, coal combustion, and manufacture of lead oxide. 

Maddock, B.G. and D. Taylor. 1980. The acute toxicity and bioaccumulation of some lead alkyl compounds in marine animals. Pages 233-261 in M. Branica and Z. Konrad (eds.). Lead in the Marine Environment. Pergamon Press, Oxford, England. 

The solubility of these compounds lends clues to their origin and timing of release. EDB is more soluble than the lead alkyls. Thus, if both EDB and TEL are present in significant amounts, the release is inferred to be quite recent. If EDB is reduced or absent, it is inferred that some exposure on the order of 5 to 10 years has occurred. Should TEL also be significantly reduced, exposure for a period in excess of 10 years is inferred. When other lead alkyls are present, it is inferred that release took place prior to 1980. 

Kehoe R Lead, alkyl compounds. In International Labour Office Encyclopaedia of Occupational Health and Safety, Vol II, L-Z, pp 1197-1199. Geneva, 1983... 

Another near future objective is to ensure development of technology that enables production of motor-fuel substitutes fhom non petroleum sources. The production of methanol-higher alcohols mixtures fhom natural gas,via syngas, remains a priority objective to obtain octane boosters capable of replacing lead alkyls and to allow the use of additional low-priced methanol. 

Another limitation on the use of catalytic oxidation is the susceptibility of the catalysts to various deactivators or poisons, although according to the vendor the phase out of the use of volatile lead alkyls as antiknock agents in U.S. gasoline, catalyst poisoning is today rarely encountered. 

Alkyl lead compounds are extremely effective gasoline antiknock agents. By decomposing to form lead oxide compounds during the gasoline combustion process, lead alkyls interrupt the rapid chain scission reactions which lead to combustion knock. Also, lead alkyls help to prevent exhaust valve seat wear and may minimize octane requirement increase. However, unless utilized in conjunction with lead scavengers such as 1,2-dichloromethane, lead deposits can accumulate within the gasoline combustion chamber. 

Lactone intermediates, 94,127, 228 Lateral overlap, orbitals, 9 Lead alkyls, 301 anti-knock, 305 thermolysis, 301, 304, 324 Leaving groups, 98, 99, 127,139, 237 ability of, 98, 251... 

Hazards Associated with Organic Chemical Manufacturing Tetraalkyl Lead by Lead Alkylation, Mitre Corp., McLean, VA, Report No. MTR-78W00364-03, May 1979. 

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