Editing Methyl tert-butyl ether (section)

==Uses==
MTBE is used as a fuel component in fuel for [[petrol|gasoline]] engines. It is one of a group of chemicals commonly known as [[oxygenate]]s because they raise the [[oxygen]] content of gasoline.

===As anti-knocking agent===
In the U.S. MTBE has been used in gasoline at low levels since 1979, replacing [[tetraethyllead]] (TEL) as an antiknock (octane rating) additive to prevent [[engine knocking]].<ref>{{Cite web |title=Overview {{!}} Methyl Tertiary Butyl Ether (MTBE) {{!}} US EPA |url=https://archive.epa.gov/mtbe/web/html/faq.html |access-date=2021-04-07 |website=archive.epa.gov |language=en}}</ref> Oxygenates also help gasoline burn more completely, [[Automobile emissions control|reducing tailpipe emissions]]. Oxygenates also dilute or displace gasoline components such as aromatics (e.g., [[benzene]]). Before the introduction of other oxygenates and octane enhancers, refiners chose MTBE for its blending characteristics and low cost.

===Alternatives to MTBE as an anti-knock agent===
Other oxygenates are available as additives for gasoline including [[alcohol fuel|ethanol]] and other ethers such as [[ETBE]].

Ethanol has been advertised as a safe alternative by agricultural and other interest groups in the U.S. and Europe. In 2003, California was the first U.S. state to start replacing MTBE with ethanol.

An alternative to ethanol is ETBE, which is manufactured from ethanol and isobutene. Its performance as an additive is similar to MTBE, but due to the higher price of ethanol compared to methanol, it is more expensive.

Higher quality gasoline is also an alternative, so that additives such as MTBE are unnecessary. [[Iso-octane]] itself is used. MTBE plants can be retrofitted to produce iso-octane from isobutylene.<ref name=nesteengineering>{{cite web |url=http://www.nesteengineering.com/default.asp?path=111,360,362,477 |title= NExOCTANE™ - Neste Jacobs |website=www.nesteengineering.com |archive-url=https://web.archive.org/web/20060106041047/http://www.nesteengineering.com/default.asp?path=111%2C360%2C362%2C477 |archive-date=January 6, 2006}}</ref><ref name=halliburton>{{Cite web |url=http://www.halliburton.com/kbr/hydroChem/petroChem/nexoctane.jsp |title=KBR - NExOCTANE™ |access-date=2006-01-31 |archive-url=https://web.archive.org/web/20060106003915/http://www.halliburton.com/kbr/hydroChem/petroChem/nexoctane.jsp |archive-date=2006-01-06 |url-status=dead }}</ref>

===As a solvent===
MTBE is sometimes used as a solvent,<ref>{{cite journal |doi = 10.1194/jlr.D700041-JLR200  |doi-access=free |pmid = 18281723 |title = Lipid extraction by methyl-tert-butyl ether for high-throughput lipidomics |journal = [[The Journal of Lipid Research]]| volume = 49 |issue = 5 |pages = 1137–1146 |year = 2008 |last1 = Matyash |first1 = V. |last2 = Liebisch |first2 = G. |last3 = Kurzchalia |first3 = T. V. |last4 = Shevchenko |first4 = A. |last5 = Schwudke |first5 = D. |pmc = 2311442}}</ref><ref>{{Cite journal |title = Sorption of methanol, dimethyl carbonate, methyl acetate, and acetone vapors in CTA and PTMSP: General findings from the GAB Analysis |journal = [[Journal of Polymer Science Part B: Polymer Physics]] |date = 2016-03-01 |issn = 1099-0488 |pages = 561–569 |volume = 54 |issue = 5 |doi = 10.1002/polb.23945 |language = en |first1 = Ondřej |last1 = Vopička |first2 = Kryštof |last2 = Pilnáček |first3 = Petr |last3 = Číhal |first4 = Karel |last4 = Friess |bibcode = 2016JPoSB..54..561V}}</ref><ref>{{Cite journal |title = Sorption of vapour mixtures of methanol and dimethyl carbonate in PTMSP: Cooperative and competitive sorption in one system |journal = [[European Polymer Journal]] |date = 2016-02-01 |pages = 243–250 |volume = 75 |doi = 10.1016/j.eurpolymj.2015.12.015 |first1 = Ondřej |last1 = Vopička |first2 = Daniel |last2 = Radotínský |first3 = Karel |last3 = Friess}}</ref> although it is used less commonly than diethyl ether. Although an ether, MTBE is a poor [[Lewis base]] and does not support formation of [[Grignard reagent]]s. It is also unstable toward strong acids. It reacts dangerously with [[bromine]].<ref>{{cite web |url=http://www.crhf.org.uk/incident09.html |title=Interaction between bromine and tert-butyl methyl ether |publisher=UK Chemical Reaction Hazards Forum |access-date=13 May 2010 |archive-url=https://web.archive.org/web/20110313064840/http://www.crhf.org.uk/incident09.html |archive-date=13 March 2011}}</ref>

MTBE forms [[azeotrope]]s with water (52.6&nbsp;°C; 96.5% MTBE)<ref name=":1">[http://www.zeon.co.jp/business_e/enterprise/spechemi/cpme_tec_sup_e_200906.pdf Zeon Corporation] {{webarchive |url=https://web.archive.org/web/20110722102229/http://www.zeon.co.jp/business_e/enterprise/spechemi/cpme_tec_sup_e_200906.pdf |date=2011-07-22 }}</ref> and methanol (51.3&nbsp;°C; 68.6% MTBE).<ref>''[[CRC Handbook of Chemistry and Physics]]'', 90th edition</ref> The solubility of water in MTBE is reported to be 1.5 g/100g at 23&nbsp;°C.<ref name=":1" />

In an investigational medical procedure called contact dissolution therapy, MTBE is injected directly into the gallbladder to dissolve cholesterol [[gallstones]]. Due to concerns of MTBE toxicity and potentially serious side effects in the event of solvent draining into the [[duodenum]], and the advent of [[laparoscopic surgery]] techniques, this procedure is considered obsolete.<ref>{{cite journal |vauthors=Schoenfield LJ, Marks JW |title=Oral and contact dissolution of gallstones |journal=[[Am. J. Surg.]] |volume=165 |issue=4 |pages=427–30 |year=1993 |pmid=8480875 |doi=10.1016/S0002-9610(05)80934-1 }}</ref><ref>{{cite news |url = https://www.nytimes.com/health/guides/disease/gallstones/treatment.html |title = Health Guide: Gallstones |newspaper = New York Times}}</ref><ref>https://www.aetna.com/cpb/medical/data/500_599/0509.html | access-date = June 3, 2024</ref>

MTBE is used in organic chemistry as a relatively inexpensive solvent with properties comparable to diethyl ether, but with a higher boiling point and less solubility in water. As a solvent, MTBE has one distinct advantage over most ethers - it has a much lower tendency to form explosive organic peroxides. It is widely used as a solvent in industry where, for safety and regulatory reasons, handling diethyl ether or other ethers is much more difficult and expensive. MTBE as a solvent is used in the oil refining industry as a method for dewaxing waxy petroleum fractions.