Methyl /erf-butyl ether

Schmidt, T.C., Schirmerb, M., Wei, H., and Haderleina, S.B., Microbial degradation of methyl /erf-butyl ether and /erf-butyl alcohol in the subsurface, Journal of Contaminant Hydrology, 70 (3-4), 173-203,... 

The industrial capacity for worldwide production of methanol in 1994 was 2.42 x 10 metric tons per year3 about 85% of which was used as a starting material in the production of other chemicals or as a solvent. Methanol is used as a raw material in the manufacture of formaldehyde. acetic acid, methyl /erf-butyl ether (MTBE), dimethyl terephthalate, methyl chloride, methyl amines, and many other chemicals. It can also be used as a clean-burning fuel. 

Degradation of methyl terf-butyl ether by bifunctional aluminum in the presence of oxygen was investigated by Lien and Wilkin (2002). Bifunctional aluminum was synthesized by sulfating aluminum metal with sulfuric acid. When the initial methyl terf-butyl ether concentration was 14.4 mg/L, 90% of methyl ferf-butyl ether degraded within 24 h forming acetone, methyl acetate, tert-hniyX alcohol, and ferf-butyl formate. Carbon disulfide was tentatively identified as a reaction product by GC/MS. Product yields were 27.6% for acetone, 18.4% for methyl acetate, 21% for tert-hniyX alcohol, and 6.1% ferf-butyl formate. When the initial concentration of methyl tert-butyl ether was reduced to 1.4 mg/L, 99.5% of methyl terCbutyl ether reacted. Yields of acetone, methyl acetate, and /erf-butyl alcohol were 54.7,17.2, and 13.2, respectively. 

A tertiary radical can be formed by elimination during AF of ter/-butyl methyl and ethyl ethers thus, isolation of the respective perfluoro-/erf-butyl ethers, e.g. 1, occurs in only 36 and 42% yield.28 Significant quantities of perfluoro(2-methylpropane) (2) are also isolated. The longer alkyl chains (ethyl and larger) appear to be slightly less prone to scission than the methyl group. Apparently, carbonyl fluoride is more readily eliminated than trifluoroacetyl fluoride, a phenomenon observed during AF of esters.29 Elimination becomes most serious in the special class of polyethers called ortho esters, e.g. 3-5.30 Cyclic ortho esters, acetals and ketals are much less affected than acyclics. 

Methyl f erf-butyl ether (MTBE, C5H120), a substance used as an octane booster in gasoline, can be made by reaction of isobutylene (C4H8) with methanol (CH40). What is the percent yield of the reaction if 32.8 g of methyl tert-butyl ether is obtained from reaction of 26.3 g of isobutylene with sufficient methanol ... 

Methyl f erf-butyl ether (MTBE), an octane booster in gasoline, can be synthesized by heating methanol and ferf-butyl alcohol with sulfuric acid ... 

Neither an integral trace (shown in blue in Figure 13-19) nor a digital integral can specifically indicate that methyl ferf-butyl ether has three methyl hydrogens and nine f erf-butyl hydrogens. Each simply shows that about three times as many hydrogens are represented by the peak at 81.2 as are represented by the peak at S3.2. We must interpret what the 3 1 ratio means in terms of the structure. 

The synthesis of thiepins 14 was unsuccessful in the case of R1 = i-Pr,79 but if the substituents in the ortho positions to sulfur arc /erf-butyl, then thiepin 14 (R1 = t-Bu R2 = Me) can be isolated in 99% yield.80 Rearrangement of diazo compound 13 (R1 = t-Bu R2 = H), which does not contain the methyl group in position 4, catalyzed by dimeric ( y3-allyl)chloropalladium gives, however, the corresponding e.w-methylene compound. The thiepin 14 (R1 = t-Bu, R2 = H) can be obtained in low yield (13 %) by treatment of the diazo compound with anhydrous hydrogen chloride in diethyl ether at — 20 C.13 In contrast, the ethyl thiepin-3,5-or -4,5-dicarboxylates can be prepared by the palladium catalysis method in satisfying yields.81... 

Diastereoselectivity varied with counterion, solvent and temperature, with the best results obtained using conditions favoring contact ion pairs. Using the potassium salt in petroleum ether diastereoselectivities were in the order of 60-70% de31. The yields were low in most cases, perhaps as a consequence of the hetereogeneous reaction conditions. Changing the solvent from petroleum ether to f erf-butyl methyl ether allowed the reaction to be conducted in a homogeneous medium. This resulted in a considerable improvement of both the yield (60-70%) and diastereoselectivity (80-90% de)30, which turned out to be independent of the haloalkane. 

Solvent effects on relative rate constants are also usually small. When a heteroaromatic compound quaternizes at more than one site, for example, the product ratio can be insensitive to solvent variations. A constant isomer ratio is recorded for methylation (Mel) of 3-/erf-butyl-6-dimethylaminopyridazine (10), in hexane, benzene, carbon tetrachloride, acetone, and acetonitrile, but not in dimethoxyethane or tetrahydrofuran. The suggestion was made that Mel may have reacted with the last two ether solvents to give an oxonium ion. Since the identity of the quaternizing agent changes, the product ratio varies as well.13... 

For the synthesis of Thiangazole, Pattenden and co-workers prepared the oxa-zole derivative 25.3 [Scheme 5.25] from the a-methyl cysteine derivative 25.1 in four steps.55 The final step in the sequence involved acidolytic cleavage of both the N-Boc and S-Boc protecting groups with anhydrous HC1 in ether. However, in certain circumstances, an N-Boc group can be cleaved in the presence of an S-Boc group and a /erf-butyl ester [Scheme 5.26).56... 

To a solution of allylic alcohol (1 equiv.) in dichloromethane (0.5 M) o-DPPBA, (1 equiv.), DMAP (0.1 equiv.) and DCC (1.1 equiv.) were successively added and the resulting mixture was stirred at room temperature until TLC analysis indicated complete consumption of the starting material. Subsequently, the reaction mixture was filtered through a plug of dichloromethane-wetted Celite and washed with additional dichloromethane. An appropriate amount of silica gel was added to the filtrate, which was then concentrated to dryness. Flash chromatography with petroleum ether/f erf-butyl methyl ether (9 1) provided the o-DPPB esters (2), usually as slightly yellow to colourless, highly viscous oils. 

Theil et al. developed a method for chemoenzymatic synthesis of both enantiomers of cispentacin [89]. frans-2-Hydroxymethylcyclopentanol, obtained by the sodium borohydride reduction of ethyl 2-oxocyclopentanecarboxylate, was monosilylated with tert-butyldimethylsilyl (TBDMS) chloride to afford 55. Lipase PS-catalysed transesterification with vinyl acetate in /erf-butyl methyl ether furnished the ester 56 and the alcohol 57. The deacetylated 58 was obtained by the Mitsunobu reaction with phthalimide, triphenylphosphine and diethyl azodicarboxylate (DEAD) to furnish the cis oriented 59 with inversion of configuration (not retention as mentioned in the original article) (Scheme 9). Desilylation, Jones oxidation and subsequent deprotection with aqueous methylamine gave the ( R,2S) enantiomer 5 [89]. The (15, 2/f) enantiomer was prepared by the same route from the silyl alcohol 57. 

The higher steric hindrance of the /erf-butyl group compared with methyl has several advantages in enantioselective reaction of the imines formed from this ether (Sections D.1.1,1.2, D.2.1.). 

Methyl r -butylsulfenate treated 48 hrs. at 35° under Ng in the dark with tri-n-butylphosphine in degassed toluene erf-butyl methyl ether. Y 98%. F. e. s. D. H. R. Barton, G. Page, and D. A. Widdowson, Chem. Commun. 1970, 1466. 

To methylmagnesium chloride [from the action of gaseous methyl chloride on 121.5 gm (5 moles) of magnesium in 1600 ml of dry di-n-butyl ether] is added 610 ml (5 moles) of /erf-amyl chloride in 1 liter of di-n-butyl ether at 5°C over a period of 8 hr. Decomposition with ice and distillation of the ether yielded the crude product at bp 37°-50°C. Washing with sulfuric acid and redistillation yielded pure neohexane, bp 49 -50°C (740 mm), 1.3688, in 36-39% yield. 

To a suspension of 1.12 g (10 mmol) of potassium /erf-butoxide in 10 mL of fert-butyl methyl ether under argon is added 5 mmol of 8 at 0°C and then 10 mmol of t-BuLi in pentane (1.5 M) dropwise. After stirring... 

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