Editing Tetraethyllead (section)

== Synthesis and properties ==
TEL is produced on an industrial scale by reacting [[chloroethane]] (ethyl chloride) with a [[sodium]]–[[lead]] [[alloy]].<ref name="Seyferth">{{cite journal |last= Seyferth |first=D. |title= The Rise and Fall of Tetraethyllead. 2 |journal= [[Organometallics]] |year= 2003 |volume= 22 |pages= 5154–5178 |doi= 10.1021/om030621b |issue= 25|doi-access=  }}</ref><ref name="Jewkes">{{cite book |last1=Jewkes |first1=John |last2=Sawers |first2=David |last3=Richard |first3=Richard |title=The sources of invention |date=1969 |publisher=W. W. Norton |location=New York |isbn=978-0-393-00502-8 |pages=[https://archive.org/details/sourcesofinventi0000jewk_x4v4/page/235 235]–237 |edition=2nd |url=https://archive.org/details/sourcesofinventi0000jewk_x4v4 |url-access=registration |access-date=11 July 2018}}</ref>

{{block indent|4 NaPb + 4 CH{{sub|3}}CH{{sub|2}}Cl → Pb(CH{{sub|3}}CH{{sub|2}}){{sub|4}} + 4 NaCl + 3 Pb}}

The product is recovered by steam distillation, leaving a sludge of lead and [[sodium chloride]].<ref>{{cite book |last1=Davis |first1=William E. |title=Emission Study of Industrial Sources of Lead Air Pollutants, 1970 |date=1973 |location=United States |publisher=Environmental Protection Agency |page=57 |url=https://books.google.com/books?id=gA05nZLq6q4C |language=en |access-date=22 March 2023 |archive-date=7 June 2023 |archive-url=https://web.archive.org/web/20230607225235/https://books.google.com/books?id=gA05nZLq6q4C |url-status=live }}</ref> TEL is a [[Viscosity|viscous]] colorless [[liquid]] with a sweet odor.<ref>{{cite book |last1=Dara |first1=S.S. |last2=Shete |first2=S.D. |title=S. Chand's Applied Chemistry Volume 2 (For 2nd Semester of Mumbai University) |publisher=S. Chand Publishing |isbn=978-81-219-3495-4 |page=93 |url=https://books.google.com/books?id=CDJlDwAAQBAJ |language=en |access-date=22 March 2023 |archive-date=7 June 2023 |archive-url=https://web.archive.org/web/20230607225236/https://books.google.com/books?id=CDJlDwAAQBAJ |url-status=live }}</ref> Because TEL is charge neutral and contains an exterior of alkyl groups, it is highly [[Lipophilicity|lipophilic]] and soluble in petrol (gasoline). This property, which allows it to dissolve so evenly and effectively in motor fuel, also allowed easy absorption by body fats and lipids and diffusion through the blood–brain barrier (BBB). The lead (II) ions (Pb<sup>2+</sup>) would accumulate within the limbic forebrain, frontal cortex, and [[hippocampus]].<ref name="Cadet & Bolla">{{cite journal |last1=Cadet |first1=J. L. |last2=Bolla |first2=K. I. |title=Environmental Toxins and Disorders of the Nervous System |journal=Neurology and Clinical Neuroscience |year=2007 |pages=1477–1488 |doi=10.1016/B978-0-323-03354-1.50115-2 |isbn=9780323033541}}</ref> Practically speaking, TEL is a "central nervous system toxin which produces an acute toxic psychosis."<ref>{{Cite journal |last=Gidlow |first=D. A. |date=2015-07-01 |title=Lead toxicity |url=https://academic.oup.com/occmed/article-abstract/65/5/348/1425465 |journal=Occupational Medicine |volume=65 |issue=5 |pages=348–356 |doi=10.1093/occmed/kqv018 |issn=0962-7480}}</ref>

There is [[Cruel and unusual punishment|no cure]] for direct poisoning by TEL. Inorganic lead compounds, such as those present in [[Exhaust gas|engine exhausts]], could be removed from the system through the administration of [[Chelation|chelating agents]], which bind to the inorganic lead and flush them out of the body. However, highly lipid-soluble TEL cannot be removed this way, and treatments are of a supportive nature.<ref>{{Cite journal |last=Gidlow |first=D. A. |date=2015-07-01 |title=Lead toxicity |url=https://academic.oup.com/occmed/article-abstract/65/5/348/1425465 |journal=Occupational Medicine |volume=65 |issue=5 |pages=5 |doi=10.1093/occmed/kqv018 |issn=0962-7480 |quote="... Unlike inorganic lead and its compounds, where chelating agents may be used in the case of poisoning, there is no specific antidote for organic lead poisoning—treatment consists of supportive treatment and adequate sedation."}}</ref>

Despite decades of research, no reactions were found to improve upon this process; it is rather difficult, involves reactive metallic sodium, and converts only 25% of the lead to TEL. A related compound, [[tetramethyllead]], was commercially produced by a different electrolytic reaction. However, tetramethyllead was even more difficult to make, and it did not find use beyond niche applications.<ref name="Seyferth" /> A highly efficient pathway utilizing ethyl chloride with a slight excess of [[lithium]] was developed, with a TEL yield over lead of over 90%. However, by then the fuel additive had started to fall out of favor and into disrepute, and the process was never put into practice.<ref name=":3">{{cite journal |last1=Seyferth |first1=Dietmar |title=The Rise and Fall of Tetraethyllead. 2 |journal=Organometallics |date=December 2003 |volume=22 |issue=25 |page=5174 |doi=10.1021/om030621b |url=https://pubs.acs.org/doi/pdf/10.1021/om030621b |language=en |issn=0276-7333 |access-date=31 August 2021 |archive-date=6 November 2021 |archive-url=https://web.archive.org/web/20211106205506/https://pubs.acs.org/doi/pdf/10.1021/om030621b |url-status=live }}</ref>