tetramethyllead

{{Chembox

| Name =

| ImageFile = Tetramethylblei.svg

| ImageFile1 = Tetramethyllead-from-xtal-3D-vdW.png

| ImageSize = 120px

| ImageAlt =

| IUPACName =

| OtherNames = Tetramethylplumbane

| SystematicName =

| Section1 = {{Chembox Identifiers

| CASNo = 75-74-1

| CASNo_Ref = {{cascite|correct|CAS}}

| Beilstein = 3902986

| ChEBI = 30183

| ChemSpiderID = 6154

| EC_number = 200-897-0

| Gmelin = 2491

| PubChem = 6394

| RTECS = TP4725000

| UNNumber = 1649 3082

| UNII = C7J62Z32IW

| UNII_Ref = {{fdacite|correct|FDA}}

| SMILES = C[Pb](C)(C)C

| StdInChI=1S/4CH3.Pb/h4*1H3;

| StdInChIKey = XOOGZRUBTYCLHG-UHFFFAOYSA-N

}}

| Section2 = {{Chembox Properties

| Properties_ref =

| C=4|H=12|Pb=1

| Appearance = Clear, highly refractive liquid

| Odor = Sweet

| Density = 1.995 g/cm³ (at 20 °C)

| MeltingPtC = -27.5

| BoilingPtC = 110

| BoilingPt_notes = (but very high vapor pressure)

| Solubility = Ether, absolute (not 96%) alcohol

}}

| Section3 = {{Chembox Hazards

| GHSPictograms = {{GHS02}}{{GHS06}}{{GHS07}}{{GHS08}}{{GHS09}}

| GHSSignalWord = Danger

| HPhrases = {{H-phrases|226|300|302|310|332|360|373|410}}

| PPhrases = {{P-phrases|201|202|210|233|240|241|242|243|260|261|262|264|270|271|273|280|281|284|301+310|301+312|302+350|303+361+353|304+312|304+340|308+313|310|312|314|320|321|322|330|361|363|370+378|391|403+233|403+235|405|501}}

| MainHazards =

| FlashPtC = 37.8

| FlashPt_notes = closed cup

| AutoignitionPt =

| NFPA-H = 4

| NFPA-F = 3

| NFPA-I = 3

}}

| Section4 = {{Chembox Related

| OtherCations = {{unbulleted list|Neopentane|Tetramethylsilane|Tetramethylgermanium|Tetramethyltin}}

| OtherCompounds =Tetraethyllead

}}

| Section5 =

| Section6 =

}}

Tetramethyllead, also called tetra methyllead and lead tetramethyl, is a chemical compound used as an antiknock additive for gasoline.{{cite web |url=https://pubchem.ncbi.nlm.nih.gov/compound/6394 |title=Tetramethyllead |website=pubchem.ncbi.nlm.nih.gov}} It is a methyl radical synthon. Its use in gasoline is being phased out for environmental considerations.{{cite book|last1=Filella |first1= Montserrat|last2=Bonet|first2=Josep

|chapter= Chapter 14. Environmental Impact of Alkyl Lead(IV) Derivatives: Perspective after Their Phase-out|pages=471–490

|publisher= de Gruyter|publication-date= 2017|series= Metal Ions in Life Sciences|volume=17|title=Lead: Its Effects on Environment and Health|year= 2017|editor1-last=Astrid|editor1-first= S.|editor2-last=Helmut|editor2-first=S.|editor3-last=Sigel |editor3-first= R. K. O.|doi=10.1515/9783110434330-014|pmid= 28731307}}

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.{{Cite web|url=https://www.cdc.gov/niosh/npg/npgd0603.html|title=CDC - NIOSH Pocket Guide to Chemical Hazards - Tetramethyl lead (as Pb)|website=www.cdc.gov|access-date=2016-06-07}}

High heat can cause tetramethyllead to explosively decompose. Consequently it cannot be stored pure in sealed containers.{{cite encyclopedia|article=Tetramethyllead|pages=763–765|first=M.|last=Baudler|encyclopedia=Handbook of Preparative Inorganic Chemistry|volume=1|edition=2|editor-first=Georg|editor-last=Bauer|translator-first=Reed F.|translator-last=Riley|year=1963|publisher=Academic Press / Scripta Technica|location=New York, NY|lccn=63-14307}}

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.