Methyl tert-butyl ether
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Preferred IUPAC name
2-Methoxy-2-methylpropane | |
Other names
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Identifiers | |
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ChEBI | |
ChemSpider | |
ECHA InfoCard
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100.015.140 |
KEGG | |
PubChem CID
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UNII | |
CompTox Dashboard (EPA)
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Properties | |
C5H12O | |
Molar mass | 88.150 g·mol−1 |
Appearance | colourless liquid |
Density | 0.7404 g/cm3 |
Melting point | −108.6 °C (−163.5 °F; 164.6 K) |
Boiling point | 55.5 °C (131.9 °F; 328.6 K) |
26 g/L (20 °C)[1] | |
Vapor pressure | 27kPa (20ºC) |
Viscosity | 3.4·10-4 Pa·s (at 25ºC) |
Hazards | |
NFPA 704 (fire diamond) | |
Flash point | −32.78 °C (−27.00 °F; 240.37 K) |
435 °C (815 °F; 708 K) | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Methyl tert-butyl ether (MTBE), also known as tert-butyl methyl ether, is an organic compound with a structural formula (CH3)3COCH3. MTBE is a volatile, flammable, and colorless liquid that is sparingly soluble in water.[1] Primarily used as a fuel additive, MTBE is blended into gasoline to increase its octane rating and knock resistance, and reduce unwanted emissions.[2][3]
Production and properties
MTBE is manufactured via the
MTBE production in the U.S. peaked in 1999 at 260,000 barrels per day[8] before dropping down to about 50,000 barrels per day and holding steady,[9] mostly for the export market. After the purchase of SABIC,[10][11] oil giant Saudi Aramco is now considered to be the world's largest producer[12] with an estimated production capacity of 2.37 million metric tons per year (mt/yr).[13] Worldwide production capacity of MTBE in 2018 was estimated to be 35 million metric tons.[14]
Uses
MTBE is used as a fuel component in fuel for
As anti-knocking agent
In the U.S. MTBE has been used in gasoline at low levels since 1979, replacing
Alternatives to MTBE as an anti-knock agent
Other oxygenates are available as additives for gasoline including
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.
As a solvent
MTBE is used in industry as a safer alternative to
MTBE forms azeotropes with water (52.6 °C; 96.5% MTBE)[22] and methanol (51.3 °C; 68.6% MTBE).[23]
In a medical procedure called contact dissolution therapy, MTBE is injected directly into the gallbladder to dissolve gallstones.[24][25]
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.
Persistence and pervasiveness in the environment
MTBE gives water an unpleasant taste at very low concentrations. MTBE often is introduced into water-supply aquifers by leaking underground storage tanks (USTs) at gasoline stations or by gasoline containing MTBE being spilled onto the ground. The higher water solubility and persistence of MTBE cause it to travel faster and farther than many other components of gasoline when released into an aquifer.[26]
MTBE is biodegraded by the action of bacteria. In the proper type of bioreactor, such as a fluidized bed bioreactor, MTBE may be removed rapidly and economically from water to undetectable levels. Activated carbon produced from coconut shells and optimized for MTBE adsorption may reduce MTBE to undetectable levels,[27] although this level of reduction is likely to occur only in the most ideal circumstances. There are currently no known published cases of any in-situ treatment method that has been capable of reducing contaminant concentrations to baseline (pre-development) conditions within the aquifer soil matrix.
According to the International Agency for Research on Cancer (IARC), a cancer research agency of the World Health Organization, MTBE is not classified as a human carcinogen. MTBE may be tasted in water at concentrations of 5–15 µg/L (5-15ppb).[28]
As of 2007, researchers have limited data about the health effects of ingestion of MTBE. The United States Environmental Protection Agency (EPA) has concluded that available data are inadequate to quantify health risks of MTBE at low exposure levels in drinking water, but the data support the conclusion that MTBE is a potential human carcinogen at high doses.[29]
Regulation and litigation in the U.S.
Restrictions on MTBE manufacturing and use
In 2000, EPA drafted plans to phase out the use of MTBE nationwide over four years.[citation needed] Some states enacted MTBE prohibitions without waiting for federal restrictions. California banned MTBE as a gasoline additive in 2002.[30] The State of New York banned the use of MTBE as a "fuel additive", effective in 2004.[31] However, MTBE is still legal in the state for other industrial uses.[32]
The
Cleanup costs and litigation
MTBE removal from groundwater and
Many lawsuits are still pending regarding MTBE contamination of public and private drinking water supplies.
Drinking water regulations
EPA first listed MTBE in 1998 as a candidate for development of a national
California established a state-level MCL for MTBE, 13 micrograms per liter, in 2000.[45]
See also
- Cyclopentyl methyl ether (CPME)
- Di-tert-butyl ether
- List of gasoline additives
- tert-Amyl methyl ether (TAME)
References
- ^ a b Record of Methyl tert-butyl ether in the GESTIS Substance Database of the Institute for Occupational Safety and Health
- ^ "Methyl tertiary butyl ether prices, markets & analysis". ICIS Explore. Retrieved 2020-06-28.
- ^ "Oxygenates". www.api.org. Retrieved 2020-06-28.
- ^ "How is Methanol Produced". METHANOL INSTITUTE. Retrieved 2020-06-29.
- ^ Anzelmo, Bryce; Wilcox, Jennifer; Liguori, Simona. "Hydrogen production via natural gas steam reforming in a Pd-Au membrane reactor. Investigation of reaction temperature and GHSV effects and long-term stability" (PDF). Journal of Membrane Science: 25–32.[permanent dead link]
- ^ "methanol | Properties, Production, Uses, & Poisoning". Encyclopedia Britannica. Retrieved 2020-06-29.
- ^ "Methyl Tertiary Butyl Ether (MTBE) Production and Manufacturing Process". ICIS Explore. Retrieved 2020-06-29.
- ^ "The United States continues to export MTBE, mainly to Mexico, Chile, and Venezuela - Today in Energy - U.S. Energy Information Administration (EIA)". www.eia.gov. Retrieved 2020-06-28.
- ^ "United States | Methyl Tertiary Butyl Ether (MTBE): Production | Economic Indicators". www.ceicdata.com. Retrieved 2020-06-28.
- ^ "Aramco completes its acquisition of a 70% stake in SABIC from the Public Investment Fund (PIF)". www.saudiaramco.com. 17 June 2020. Retrieved 2020-06-29.
- ^ "Saudi Aramco buys SABIC shares on market as it completes acquisition". Reuters. 2020-06-14. Retrieved 2020-06-29.
- ^ "Saudi Aramco to have largest MTBE capacity in Middle East and Asia". Retrieved 2020-06-29.
- ^ "Saudi Aramco's MTBE trading volume likely to rise after Sabic purchase | S&P Global Platts". www.spglobal.com. 2019-04-09. Retrieved 2020-06-29.
- ^ "MTBE annual production capacity globally 2023". Statista. Retrieved 2020-06-28.
- ^ "Overview | Methyl Tertiary Butyl Ether (MTBE) | US EPA". archive.epa.gov. Retrieved 2021-04-07.
- ^ "NExOCTANE™ - Neste Jacobs". www.nesteengineering.com. Archived from the original on January 6, 2006.
- ^ "KBR - NExOCTANE™". Archived from the original on 2006-01-06. Retrieved 2006-01-31.
- PMID 18281723.
- ISSN 1099-0488.
- .
- ^ "Interaction between bromine and tert-butyl methyl ether". UK Chemical Reaction Hazards Forum. Archived from the original on 13 March 2011. Retrieved 13 May 2010.
- ^ Zeon Corporation Archived 2011-07-22 at the Wayback Machine
- ^ CRC Handbook of Chemistry and Physics, 90th edition
- PMID 8480875.
- ^ "Health Guide: Gallstones". New York Times.
- ^ San Francisco Bay Area Regional Water Quality Control Board Integrated Basin Management Plan (2004) Archived 2008-02-29 at the Wayback Machine
- ^ link text Archived 2011-07-28 at the Wayback Machine
- S2CID 97168152.
- ^ "Methyl Tertiary Butyl Ether (MTBE) | US EPA".
- ^ "California Reformulated Gasoline Phase 3". Sacramento, CA: California Air Resources Board. 2015-07-24. Archived from the original on 2018-04-07. Retrieved 2018-04-07.
- ^ "Spill Response & Remediation FAQ". Chemical and Pollution Control. Albany, NY: New York State Department of Environmental Conservation. Retrieved 2018-04-06.
- ^ State of New York. New York Consolidated Laws, Agriculture and Markets Law. "AGM § 192-g. Methyl tertiary butyl ether; prohibited."
- ^ http://www.cnn.com/2005/POLITICS/04/21/energy.bill.mtbe.ap/ Archived 2005-04-22 at the Wayback Machine
- ^ "House approves $12 billion energy package". NBC News. 2005-04-22.
- ^ Charles Babington, House Again Passes GOP Energy Measures, Washington Post, June 16, 2004, at A4 (House passes Energy Bill, but Senate opponents of MTBE provision in House Bill have the votes to prevent its enactment).
- Pub. L.109–58 (text) (PDF). Approved 2005-08-08.
- ^ "MTBE Cleanup Estimates". SIGMA Weekly Report. Fairfax, VA: Society of Independent Gasoline Marketers of America (SIGMA). 2005-05-23. Archived from the original on 2009-10-09.
- ^ "Long Island Utility Fighting to Defeat MTBE Safe Harbor". The MTBE e-Resource. New York, NY: Napoli Bern, LLP. 2004-03-16. Archived from the original on 2007-10-20.
- ^ "Oil Companies Pay Santa Monica MTBE Cleanup Costs". Environment News Service. Ecology Prime Media, Inc. 2005-02-17.
- ^ Navarro, Mireya (2009-10-20). "City Awarded $105 Million in Exxon Mobil Lawsuit". The New York Times. Retrieved 2010-05-12.
- ^ Earle, Sarah (2013-04-09). "Exxon Mobil is Found Negligent in New Hampshire MTBE Use". Bloomberg.
- ^ EPA (1998-03-02). "Announcement of the Drinking Water Contaminant Candidate List." Federal Register, 63 FR 10274
- ^ "Drinking Water Regulations Under Development or Review". EPA. 2020-01-27.
- ^ "How EPA Regulates Drinking Water Contaminants". EPA. 2017-05-03.
- ^ "MTBE: Regulations and Drinking Water Monitoring Results". Sacramento, CA: California State Water Resources Control Board. 2014-08-04.