Methyl-iert-butyl ether

MTBE Methyl iert-butyl ether (tert-butyl methyl ether)... 

WaUington, T.J., Dagaut, P., Liu, R., Kuoylo, M.J. (1988c) Gas-phase reactions of hydroxyl radicals with the fuel additives methyl iert-butyl ether and fert-butyl alcohol over the temperature range 240-440 K. Environ. Sci. Technol. 22, 842-844. 

The next step in the cracker C4 treatment is the isolation of isobutene from Raffinate 1. To realize this step. Raffinate 1 is reacted with water or methanol to form tert-butanol or methyl-iert-butyl ether, respectively. Ahematively, Raffinate 1 can be treated with an acid catalyst to convert isobutene selectively into isooctene, an important fuel additive. All Raffinate 1 treatment processes have in common that isobutene reacts selectively from the mixture to form a compound of significantly lower vapor pressure. Thus, in the subsequent distillation process, the isobutene adduct is the low boiling component and remains at the bottom of the distillation column while the remaining C4-compounds can be isolated at the top. The obtained distillate is called Raffinate 2 and consists typically of 45% 1-butene, 30% 2-butenes, 19% butanes, 6% isobutane, and traces of 1,3-butadiene. Raffinate 2 can be applied as feedstock for a distillation unit that isolates 1-butene from the mixture for copolymerization apphcations. Alternatively, Raffinate 2 can be fed into a dimerization unit where either a homogeneous (Dimersol-process) or a heterogeneous Ni-catalyst (Octol process) converts the butenes into Cg dimers. Unconverted feedstock of this unit is called Raffinate 3. It typically contains around 70% butane and isobutane and 30% of remaining linear butenes. Raffinate 3 is recycled to the cracker to serve their as an addition to the cracker feed. 

Fig. 5. Solubility of various ethers in water at 25°C [19-24], Abbreviations MTBE, methyl tert-butyl ether ETBE, ethyl iert-butyl ether TAME, tert-amyl methyl ether TAEE, tert-amy ethyl ether DIPE, diisopropyl ether BTBE, butyl iert-butyl ether.

The monooxygenase from Burkholderia cepacia G4/PR1 in which the synthesis of toluene-2-monooxygenase is constitutive is able to degrade a number of ethers including diethyl ether and n-butyl methyl ether, though not iert-butyl methyl ether (Hur et al. 1997). 

We choose the first approach because it is an SN2 reaction on the unhindered substrate, methyl bromide. The second approach requires an SN2 reaction on a hindered tertiary alkyl halide, a very poor choice. Indeed, we would expect that the reaction of methoxide ion with iert-butyl bromide could not give any ether at all but would proceed entirely by E2 elimination ... 

Dimethyl-2-oxybutyl 4-Methoxyphenyl Tellurium Dichloridch A suspension of 1.02 g (3.0 mmol) of 4-methoxyphenyl tellurium trichloride in 10 m/ benzene kept under an atmosphere of nitrogen is mixed with 0.3 g (3.0 mmol) iert.-butyl methyl ketone. The mixture is refluxed for 72 h and then treated with methanol/watcr (1 1) and extracted with chloroform. The organic layer is separated, dried with anhydrous magnesium sulfate, filtered, and the solvent evaporated from the filtrate. The residual yellow oil is chromatographed on a silica gel column with chloroform as the mobile phase. The product is rccrystallized from chloroform/petroleum ether (30-60°) yield 60%, m.p. 90-92°. 

Collect the precipitated PEG-boundtV,tV -di(Boc)-protected guanidine on a glass funnel and thoroughly wash with cold iert-butyl methyl ether (20 mL, twice). Dry the resulting PEG-bound A,iV -di(Boc)-protected guanidine in vacuo to get the desired product in excellent yield. 

Precipitate the polymer from the homogenous solution by adding iert-butyl methyl ether (20 mL). 

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