Methyl t-butyl ether MTBE

United States, methanol derived from natural gas as a fuel additive is a promising future market. Methanol has neither the environmental problems of methyl-t-butyl ether (MTBE), nor the evaporating qualities of ethanol. 

The dwell time was 200 msec for the analytes and 100 msec for the IS. At least 500 extracted samples were injected onto each column without any column regeneration. No solvent evaporation and reconstitution steps were involved. Ethyl acetate was preferred over methyl t-butyl ether (MTBE) because MTBE caused pulp-up of the mat. Six blank plasma lots were tested for matrix interference and none was detected in the analyte or IS region. When 100 ng/mL of the analytes were spiked into the blank plasma samples, the relative standard deviations were 1.0 and 1.5% for omeprazole and its metabolite, respectively. Precision and accuracy figures are given in Table 1.9. 

In 1984 methyl t-butyl ether (MTBE) broke into the top 50 for the first time with a meteoric rise in production from 0.8 billion lb in 1983 to 1.47 billion lb in 1984 to be ranked 47. In 1990 it was 24 with production over 6 billion lb, and in 1995 it was 12 at 18 billion lb. A full discussion of the current economic status of MTBE is given in Chapter 7, Section 4 as the important gasoline octane enhancer. That is its only major use. MTBE is manufactured by the acid catalyzed electrophilic addition of methanol to isobutylene. 

Isobutylene now finds considerable use in producing methyl t-butyl ether (MTBE) by reacting it with methanol,... 

The additives used in oxygenated gasoline are alcohols and ethers, the most common of which are ethanol (ethyl alcohol grain alcohol) and methyl t-butyl ether (MTBE). Two less commonly used additives are ethyl t-butyl ether (ETBE) and t-amyl methyl ether (TAME). The chemical structures of these four additives are shown in the diagram on page 24. 

Recent developments and concern over the control of fuel exhaust emissions have led to the increased use of combustion system detergents, oxygenates and cetane improvers in fuel. Oxygenated blend components such as ethanol, methyl t-butyl ether (MTBE), ethyl t-butyl ether (ETBE), and /-amylmethyl ether (TAME) are also used to help limit the exhaust emissions from fuel. 

Under the same reaction conditions, acetaldehyde and butyraldehyde displayed near-complete conversion (greater than 95%). The photocatalytic oxidation of the alcohol 1-butanol displayed similarly high conversion levels, although conversion of methanol was somewhat lower. The oxygenated compounds methyl-t-butyl ether (MTBE), methyl acrylate, 1,4 dioxane, and vinyl acetate displayed conversion levels ranging from 92% to 100%. The lowest conversion levels of the oxygenated compounds studied were seen with the ketones used [acetone and 2-butanone (methylethylketone)], which displayed conversions of approximately 80%. The initial conversion levels seen with -hexane were similar... 

The catalytic alkylation of isobutane with C3—C5 alkenes was commercialized in the US during WW II. Blending the alkylate product with catalytically cracked gasoline provided high-octane aviation fuel. The introduction of aromatic and oxygenated fuel additives, such as methyl t-butyl ether (MTBE), pushed alkylation to the sidelines. However, in the 1990s, when the environmental effects of such additives were realized, alkylation regained its importance [191]. 

Lithium chloride (2.6 g) is dissolved in THF (170 mL). Dimethyl-(2-oxo-4-phenylbutyl)phosphonate (7.87 g) and triethylamine (4.3 mL) are added. The mixture is stirred and cooled to -10°C. A solution of the Corey aldehyde benzoate, (lS,5R,6R,7R)-6-formyl-7-(benzyloxy)-2-oxabicyclo[3.3.0]octan-3-one (8.42 g) in THF (75 mL) is added to the reaction mixture over three hours. The resulting mixture is stirred for 18 hours at -10°C. At the end of this time, methyl t-butyl ether (MTBE) (100 mL) is added and the mixture warmed to 0-20°C. Sodium bisulfite (38%, 100 mL) is added and the two-phase mixture was stirred for 10 min. The phases are separated and the organic phase is washed with saturated aqueous sodium bicarbonate solution (100 mL). The organic phase is separated and concentrated under reduced pressure to a volume of <100 mL. Ethyl acetate (200 mL) is added and the... 

A mixture of (R)-4-benzyl albuterol as a free base (3.2 g, 9.73 mmol) and 10% Pd/C (0.64 g) in 24 mL of ethanol (denatured with 5 vol % 2-propanol) is shaken on a Parr-hydrogenator under 50 psi of hydrogen at room temperature for 3 hours. The catalyst is removed by filtration and the filtrate is concentrated to ca. 9 mL in volume containing crude (R)-albuterol and treated with anhydrous HCI in ether (1.0 M, 9.5 mL, 0.98 eq) at 0°-5°C. After 30 min at room temperature, 9 mL of methyl t-butyl ether (MTBE) is added, the resulting mixture is stirred at room temperature for 30 min and at 0°-5°C for 2 hours. The white solid (R)-albuterol hydrochloride is collected by filtration and recrystallized from 25 mL of ethanol and 12.5 mL of MTBE to give pure (R)-albuterol hydrochloride (2.17 g, 80.9% yield, 99.6% purity), white powder. 

Of all the oxygenates, methyl-t-butyl ether (MTBE) is attractive for a variety of technical reasons. It has a low vapor pressure, can be blended with other fuels without phase separation, and has the desirable octane characteristics. If oxygenates achieve recognition as vehicle fuels, the biggest contributor will probably be methanol, the production of which is mostly from synthesis gas derived from methane. 

The /-butyl alcohol can be used to increase the octane number of unleaded gasoline or it can be made into methyl t-butyl ether (MTBE) for the same application. The alcohol can also be dehydrated to isobutylene, which in turn is used in alkylation to give highly branched dimers for addition to straight-run gasoline. An alternative reactant in this method is ethylbenzene hydroperoxide. This eventually forms phenylmethylcarbinol along with the propylene oxide, and the alcohol is dehydrated to styrene. Thus, the yield of the by-product can be varied depending on the demand for substances such as /-butyl alcohol or styrene. 

Snyder, Glajch and Kirkland [570) introduced two new parameters to describe the selectivity effects in the optimization triangle for LSC. If methylene chloride (MC), acetonitrile (ACN) and methyl t-butyl ether (MtBE) are used as the preferred modifiers in n-hexane, then an empirical solvent selectivity parameter (m) can be defined which is low for methylene chloride and can be made equal for the other two binary solvents. The latter is achieved by adding the appropriate amount of methylene chloride to the hexane-ACN binary. Addition of MC is required at any rate, because hexane and ACN are not miscible in all proportions. By definition we can assume m to equal zero for the hexane-MC binary mixture and m to equal one for the two other binaries. 

Methyl t-Butyl Ether (MTBE). In 1980, MTBE was the fastest-growing derivative of methanol. This is a result of its only significant use, which is as an antiknock agent replacing lead in gasoline. In 1990, it was the fastest-growing chemical in the world. The world production has reached 48 billion in 1999. The U.S. production was about 30 billion lb, which was 63 percent of world capacity. 

Methyl t-butyl ether (MTBE) Henry s law constant vs. 1/T... 

In the United States, passage of the 1990 Clean Air Act Amendments (CAAAs) led to the development of Federal programs that required oxygen-containing compounds be blended in gasoline to reduce carbon monoxide emissions. Examples of compounds used as oxygenates are methyl t-butyl ether (MTBE), ethanol (EtOH), ethyl t-butyl ether (ETBE), t-amyl methyl ether... 

Ether synthesis produces branched ethers like methyl t-butyl ether (MTBE) by reacting methanol (or ethanol) with branched alkenes such as isobutene. These ethers are valuable for their high octane quality and also, on account of the oxygen they contain, their ability to reduce both CO and hydrocarbon exhaust emissions. Alcohols, such as methanol, manufactured from natural gas or coal, and ethanol, produced by fermentation, are other oxygenated components in limited use. 

In the isobutane process the f-butanol (TBA) co-product is converted to the gasoline additive, methyl t-butyl ether (MTBE), via dehydration to isobutene and reaction with methanol. The theoretical weight ratio of TBA/PO is 1.32 1 but commercial plants produce 2-3 kg TBA per kg, depending on demand. Because of the very large gasoline pool, marketing 2-3 kg of TBA per kg PO is not a problem. 

As an alternative to distillation and in accord with the observations of the submitter, the checkers have shown that the reaction mixture can be diluted with 100 ml of methyl t-butyl ether (MTBE), and filtered through a column of 150 g of silica gel with sufficient flushing by MTBE to remove all product. Concentration of the MTBE on a rotary evaporator followed by keeping the resulting oil at 1 mm/25° for 24 hr affords product of comparable purity, except for traces of MTBE, and slightly improved yield. 

Semi-rigid or Type II rigid poly(vinyl chloride) specimens described by Seymour (15) were initially investigated to determine if such polymers could be used in service where the PVC could come into contact with either t-butyl alcohol (TBA) or methyl t-butyl ether (MTBE). This work now has been expanded to Include a variety of oxygenated solvents (Table I) including those studied by Hansen (11). 

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