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Tetramethyllead

Chemical compound From Wikipedia, the free encyclopedia

Tetramethyllead

Tetramethyllead, also called tetra methyllead and lead tetramethyl, is a chemical compound used as an antiknock additive for gasoline.[2] It is a methyl radical synthon.[1] Its use in gasoline is being phased out for environmental considerations.[3]

Quick Facts Names, Identifiers ...
Tetramethyllead
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Names
Other names
Tetramethylplumbane
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.000.816
EC Number
  • 200-897-0
RTECS number
  • TP4725000
UNII
UN number 1649 3082
  • InChI=1S/4CH3.Pb/h4*1H3;
    Key: XOOGZRUBTYCLHG-UHFFFAOYSA-N
  • C[Pb](C)(C)C
Properties[1]
C4H12Pb
Molar mass 267.3 g·mol−1
Appearance Clear, highly refractive liquid
Odor Sweet
Density 1.995 g/cm3 (at 20 °C)
Melting point −27.5 °C (−17.5 °F; 245.7 K)
Boiling point 110 °C (230 °F; 383 K) (but very high vapor pressure)
Ether, absolute (not 96%) alcohol
Hazards
GHS labelling:
GHS02: FlammableGHS06: ToxicGHS07: Exclamation markGHS08: Health hazardGHS09: Environmental hazard
Warning
H226, H300, H302, H310, H332, H360, H373, H410
P201, P202, P210, P233, P240, P241, P242, P243, P260, P261, P262, P264, P270, P271, P273, P280, P281, P284, P301+P310, P301+P312, P302+P350, P303+P361+P353, P304+P312, P304+P340, P308+P313, P310, P312, P314, P320, P321, P322, P330, P361, P363, P370+P378, P391, P403+P233, P403+P235, P405, P501
NFPA 704 (fire diamond)
ThumbHealth 4: Very short exposure could cause death or major residual injury. E.g. VX gasFlammability 3: Liquids and solids that can be ignited under almost all ambient temperature conditions. Flash point between 23 and 38 °C (73 and 100 °F). E.g. gasolineInstability 3: Capable of detonation or explosive decomposition but requires a strong initiating source, must be heated under confinement before initiation, reacts explosively with water, or will detonate if severely shocked. E.g. hydrogen peroxideSpecial hazards (white): no code
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3
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Flash point 37.8 °C (100.0 °F; 310.9 K) closed cup
Related compounds
Related compounds
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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The National Institute for Occupational Safety and Health (NIOSH) in the United States has identified tetramethyllead as a potential workplace hazard. The recommended time-weighted average exposure limit to tetramethyllead is 0.075 milligrams per cubic meter during a 10-hour workday; the OSHA permissible exposure limit is the same value assuming an 8-hour workday.

Exposure to tetramethyllead can affect the central nervous system, the kidneys, and the cardiovascular system. Tetramethyllead can be absorbed through inhalation, through eye contact, through skin absorption, and by ingesting the substance. Symptoms of exposure include insomnia, coma, seizure, mania, delirium, loss of appetite, nausea, hypotension, anxiety, restlessness, and nightmares. First aid measures for exposure include artificial respiration, immediate eye irrigation, and immediate washing with water. Immediate medical attention should be sought if tetramethyllead is ingested.[4]

High heat can cause tetramethyllead to explosively decompose. Consequently it cannot be stored pure in sealed containers.[1]

Tetramethyllead may be synthesized from disproportionate transmetalation of the quasi-Grignard reagent methylmagnesium chloride onto plumbous chloride:

PbCl2 + MeMgCl → PbMe4 + Pb + MgCl2

The process requires substantial care, as both methyl chloride and tetramethyllead are extremely volatile.[1]

See also

References

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