Methyl tert-butyl ether preparation

Biopract provides technological products and processes for industry, agriculture, and environment. They not only produce technical enzyme preparations but also develop enzymes for applications in agriculture, food, and textile industry as well as in environmental technologies. On the later, bioremediation has been an area of service delivery from Biopract. Their activities regards microbial preparations for the bioremediation of organic contaminants (mineral oil (MKW), polycyclic aromatic hydrocarbons (PAH), benzene, toluene, ethylbenzene, xylene (BTEX), methyl-tert-butyl ether (MTBE), volatile organic hydrocarbons (VOC), and dimethyl sulfoxide (DMSO)). 

To date, only a few examples of laboratory preparative-scale processes based on purified enzyme have been reported. Several studies have focused on the small-scale implementation of processes associating a new co-factor regenerating system, enzyme immobilization, membrane reactor, continuous substrate feeding, or resin-based SFPR with various results [110], Using the outstanding stabihty of PAMO, a 200 ml biotransformation of 5g/l phenyl cyclohexanone by an engineered mutant under two-Hquid phase conditions using methyl tert-butyl ether as solvent was described [102]. 

MeS02-PCBs are initially co-extracted from tissue with other OHS and lipids. Lipid-rich tissues such as adipose, liver and lung have been homogenized with dichloromethane (DCM) and n-hexane/2-propanol (3 2) to co-extract lipid and OHS [95,117, 118]. Tissues have also been homogenized with acetone/n-hexane and extracted with n-hexane/diethyl ether or methyl tert-butyl ether (MTBE) [119]. Mammalian adipose and liver and whole fish have been dehydrated with sodium sulfate prior to extraction with n-hexane/DCM (1 1) [11, 96]. Human liver and feces have been extracted with benzene and refluxing by Soxhlet [120], Formic acid has been added to milk samples in preparation for further cleanup [16], After extraction, OHS and aryl methyl sulfones have been separated from lipids by various techniques. Lipid destructive strategies include saponifi-... 

Terpenes are reputed to increase cholesterol solubility in bile, though are less effective than bile acids. There are two such preparations available, Rowatinex and Rowachol , containing some combination of the following anethol, borneol, camphene, cineole, mendone, menthol, pipene and renchone, in olive oil. Direct contact dissolution by direct injection of organic solvents, such as methyl tert-butyl ether (MTBE), is sometimes used. 

The first efforts to address this issue involved hydrazone ( ) 62 (Scheme 2.9), prepared as a mixture E/Z 92 8) and separated via flash chromatography as the pure ( ) isomer in 75% yield. In this preparation, the oxazolidinone N amination was accomplished using a solution of monochloramine in methyl tert butyl ether [45], furnishing a quantitative yield of the N amino 2 oxazolidinone, which in turn was condensed with methyl pyruvate to afford 62. Addition of ethyl iodide to ( ) 62 using the Mn mediated photolysis conditions as described above gave 66% yield ofthe ethyl adduct, with a modest diastereomer ratio of 70 30, while the correspond ing isopropyl addition was very effective (85% yield, dr 92 8). Variation in the stoichiometry indicated that amounts less than 2 equiv of Lewis acid proportionally lowered the diastereoselectivity, suggesting that, in this case, the ester may participate... 

Hard, G. C. (2006). Expert review of kidney histopathology in the 2-year carcinogenicity study of methyl tert butyl ether (MTBE) administered to Fischer 344 rats by vapor inhalation. Report prepared for Lyondell Chemical Company, October 10th, Houston, Texas. 

The VPO catalyst was prepared by a method described previously [5]. The bulk molar PA ratio of the catalyst was 1.26 and the surface area was 44 m2/g. The catalyst was equilibrated for over 80 hours at the n-pentane/air reaction mixture at the temperature of about 390°C before measurements. Silicium carbide (Prolabo, purity > 99 % grain fraction 0.35 mm), n-pentane (Aldrich, purity > 99 % impurity identified as 2-pentenes) and methyl-tert-butyl ether (MTBE) (Aldrich, purity > 98 %) were used without further purification. 

Hard GC (2006) Expert Review of Kidney Histopathology in the 2-Year Carcinogenicity Study of Methyl Tert Butyl Ether (MTBE) Administered to Fischer 344 Rats by Vapor Inhalation, 18 pp, prepared for Lyondell Chemical Company, Hous-... 

Olah et al. reported the triflic acid-catalyzed isobutene-iso-butylene alkylation, modified with trifluoroacetic acid (TFA) or water. They found that the best alkylation conditions were at an acid strength of about//q = —10.7, giving a calculated research octane number (RON) of 89.1 (TfOH/TFA) and91.3 (TfOH/HaO). Triflic acid-modified zeohtes can be used for the gas phase synthesis of methyl tert-butyl ether (MTBE), and the mechanism of activity enhancement by triflic acid modification appears to be related to the formation of extra-lattice Al rather than the direct presence of triflic acid. A thermally stable solid catalyst prepared from amorphous silica gel and triflic acid has also been reported. The obtained material was found to be an active catalyst in the alkylation of isobutylene with n-butenes to yield high-octane gasoline components. A similar study has been carried out with triflic acid-functionalized mesoporous Zr-TMS catalysts. Triflic acid-catalyzed carbonylation, direct coupling reactions, and formylation of toluene have also been reported. Tritlic acid also promotes transalkylation and adaman-tylation of arenes in ionic liquids. Triflic acid-mediated reactions of methylenecyclopropanes with nitriles have also been investigated to provide [3 + 2] cycloaddition products as well as Ritter products. Tritlic acid also catalyzes cyclization of unsaturated alcohols to cyclic ethers. ... 

Vatani, H. and Yazdi, A.S. (2014) lonic-liquid-mediated poly(dimethylsiloxane)-grafted carbon nanotube fiber prepared by the sol-gel technique for the head space solid-phase microextraction of methyl tert-butyl ether using GC.J. Sep. Scl, 37 (1-2), 127-134. 

A hitherto unpublished preparation of diazomethane is given on p. 16. The starting material is the commercially available bis-(N-methyl-N-nitroso)-terephthalamide, and the procedure conveniently affords 0.76 to 0.86 mole of ethereal diazomethane. Ozonization in polar solvents is illustrated by two preparations (pp. 41 and 46). Many other unusual and interesting preparations are included, such as ruthenocene (p. 96), N,N-di thyltri-chlorovinylamine (p. 21), phenyl tert-butyl ether (p. 91), and tetramethylammonium 1,1,2,3,3-pentacyanopropenide (p. 99). 

The preparation of /m-butyl ethers requires a large excess of isobutene (bp -6.9 °C) and the inconvenience and potential hazard of a pressure vessel or a sealed tube in some cases, ten-Amyl (T m) ethers have the same lability as tert-butyl ethers towards acids, and they are prepared the same way, by reaction of the alcohol with 2-methyl-l-butene (bp 31 °C) in the presence of trifluoroborane etherate, but they require only a slight excess of the reagent [Scheme 4.128].228 Deprotection of rm-butyl and fer/-amyl ethers can be accomplished by treatment with a catalytic amount of TBSOTf. When a stoichiometric... 

The initial asymmetric synthesis (see Scheme 5.2) of pyrrolidine acid 3 suffered from a chiral HPLC bottleneck. As a result, chiral salt resolution was investigated. The rapid discovery of a crystalline di-p-toluoyl-D-tartaric acid salt provided the necessary means to resolve and purify the desired diastereomer. Using 0.65 equivalent of the acid in methyl (cr(-butyl ether (MTBE), the crystallized salt was shown to be a 92 8 ratio of (3S,4R) (3R,4S) diastereomers. The resolved tartaric acid salts were then recrystalhzed from n-butanol to ratios of >99 1 in a 42% overall yield on a 2-kg scale. Further improvements were made in the preparation of the azomethine ylide precursor 38. In step 1, using dimethyl sulfoxide (DMSO) as the solvent, the reaction temperature of trimethylsilylmethylation of tert-butylamine was lowered from 200°C used in the original synthesis to 80°C. In step 2, substituting n-butanol in place of methanol reduced the amount of oligomerization observed and increased the yield to 69%. Overall, these improvements allowed for the preparation of pyrrolidine acid 3 in 22% overall yield in 99% ee from cinnamate 39 (Scheme... 

Acid catalyzed addition of alcohols to alkenes is sometimes used Indeed before Its use as a gasoline additive was curtailed billions of pounds of tert butyl methyl ether (MTBE) was prepared by the reaction... 

Both methyltriethylphosphonium fluoride and methyltributylphospho-nium fluoride have been prepared The latter generates benzyl fluoride from benzyl chloride in 80% yield and ethyl fluoroacetate from ethyl bromoacetate in 53% yield Methyltnbutylphosphonium fluoride converts 1-bromododecane to a 50 50 mixture of 1-fluorododecane and 1-dodecene Methyltnbutylphosphonium fluoride also quantitatively forms styrene from 1-bromo-1-phenylethane [26] Methyl-tnbutylphosphonium fluonde is the reagent of choice for the conversion of N,N dimethylchloroacetamide to its fluoride, but it is not able to convert chloro-acetonitnle to fluoroacetomtrile Methyltnbutylphosphonium fluoride changes chloromethyl octyl ether to the crude fluoromethyl ether in 66% yield The stereoselectivity of methyltnbutylphosphonium fluoride is illustrated by the reac tions of the 2-tert-butyl-3-chlorooxiranes [27] (Table 2)... 

This gives tautomeric mixtures119 when the tert-butyl group is removed. The methyl ether has been used to obtain 3-hydroxy-2-carbonyl derivatives in the selenophene series.120 The unsubstituted 2-hydroxyselenophene system has been prepared by hydrogen peroxide oxidation of 2-selenophene-boronic acid.121 However, in the 5-methyl-substituted system deboronation became such an important side reaction that 5-methyl-2-hydroxyselenophene had to be prepared by acid-catalyzed dealkylation of 5-methyl-2-fert-butoxy-selenophene. Both 2-hydroxy- and 5-methyl-2-hydroxyselenophene exist mainly as 3-selenolene-2-ones (93) and for the 5-methyl derivative it was possible to isolate the / ,y-unsaturated form (92) and follow the tautomeric isomerization. The activation parameters thus obtained were compared with those for the corresponding furan and thiophene systems. 

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