Ethers experiments

Groundwater contaminant plumes from accidental gasoline releases often contain methyl-tert-butyl ether. Experiments with certain soil microorganisms showed that a culture able to degrade methyl-tert-butyl ether did not degrade benzene and toluene. Further interactions were observed [468]. 

An acid-catalyzed cleavage that occurs when hydriodic acid (HI) mixes with ethers is the most significant reaction that ethers experience. This reaction proceeds via a nucleophilic substitution mechanism. Primary and secondary alkyl ethers react by an S 2 mechanism, while tertiary, benzylic, and alcylic ethers cleave by an S 1 mechanism. A typical S 2 reaction would be the reaction of ethylisopropyl ether with HI. The mechanism for this reaction is ... 

Partial Degradation of Low-Density Lipoproteins by Ether—Experiment Conditions... 

Mt. Denali in Alaska is the tallest peak in the United States (20,320 ft), (a) If the barometric pressure at the top of the mountain is 340 torr, at what temperature will water boil there Refer to Appendix B. (b) If the temperature at the top is 12 C, would a container of diethyl ether experience a pressure greater than the local atmospheric pressure (See Figure 11.22.)... 

An adequate prediction of multicomponent vapor-liquid equilibria requires an accurate description of the phase equilibria for the binary systems. We have reduced a large body of binary data including a variety of systems containing, for example, alcohols, ethers, ketones, organic acids, water, and hydrocarbons with the UNIQUAC equation. Experience has shown it to do as well as any of the other common models. V7hen all types of mixtures are considered, including partially miscible systems, the... 

In an experiment, a slight excess of the hydride is employed to ensure the complete reduction the unused hydride must then be destroyed. This can be done by the cautious addition of (rt) water, or (6) ordinary undried ether, which will ensure that the supply of water is both small and gradual, or (c) an ester such as ethyl acetate, which will be reduced to ethanol. The first of these methods, namely the addition of water, is hazardous and should be avoided. 

In the following experiment, salicylic acid is reduced to o-hydroxybenzyl alcohol (or saligenin), which being crystalline is readily isolated the excess of hydride is destroyed by the addition of undried ether, and the aluminium hydroxide then brought into solution by the addition of sulphuric acid. 

Amount of material required. It is convenient to employ an arbitrary ratio of 0 10 g. of solid or 0 20 ml. of liquid for 3 0 ml. of solvent. Weigh out 0 10 g. of the finely-powdered solid to the nearest 0 01 g. after some experience, subsequent tests with the same compound may be estimated by eye. Measure out 0-20 ml. of the liquid either with a calibrated dropper (Fig. 11,27, 1) or a small graduated pipette. Use either a calibrated dropper or a graduated pipette to deliver 3 0 ml. of solvent. Rinse the delivery pipette with alcohol, followed by ether each time that it is used. 

Fission of ethers with hydriodic acid. Reflux 1 ml. of the compound with 5 ml. of freshly distilled constant b.p. hydriodic acid (b.p. 126-128°) for 2-3 hours in a small flask fitted with a double surface condenser. Add 10 ml. of water, distil and collect about 7 ml. of liquid. Decolourise the distillate by the addition of a little sodium bisulphite and separate the two layers by means of a dropper pipette. If the original compound is suspected to be an aliphatic ether, determine the b.p. of the iodide by the Siwoloboff method (Section 11,12) if the amount of product is insufficient, repeat the original experiment. 

In a typical experiment 105 mg (0.50 mmol) of 3.8c, dissolved in a minimal amount of ethanol, and 100 mg (1.50 mmol) of 3.9 were added to a solution of 1.21g (5 mmol) of Cu(N03)2 BH20 and 5 mmol of ligand in 500 ml of water in a 500 ml flask. -Amino-acid containing solutions required addition of one equivalent of sodium hydroxide. When necessary, the pH was adjusted to a value of 5 ( -amino acids) and 7.5 (amines). The flask was sealed carefully and the solution was stirred for 2A hours, followed by extraction with ether. After drying over sodium sulfate the ether was evaporated. Tire endo-exo ratios were determined from the H-NMR spectra of the product mixtures as described in Chapter 2. 

Alkvl Azides from Alkyl Bromides and Sodium Azide General procedure for the synthesis of alkyl azides. In a typical experiment, benzyl bromide (360 mg, 2.1 mmol) in petroleum ether (3 mL) and sodium azide (180 mg, 2.76 mmol) in water (3 mL) are admixed in a round-bottomed flask. To this stirred solution, pillared clay (100 mg) is added and the reaction mixture is refluxed with constant stirring at 90-100 C until all the starting material is consumed, as obsen/ed by thin layer chromatographv using pure hexane as solvent. The reaction is quenched with water and the product extracted into ether. The ether extracts are washed with water and the organic layer dried over sodium sulfate. The removal of solvent under reduced pressure affords the pure alkyl azides as confirmed by the spectral analysis. ... 

In some experiments the presence of hexane is undesirable in view of the volatility of the products. In these cases one can use butyllithium in pentane (prepared from butyllithium in hexane, by replacing the hexane with pentane see Exp. 10) or ethyllithium in diethyl ether, prepared from ethyl bromide and 11thiurn (see Exp. 1). 

Quach, D. T. Giszkowski, N. A. Einlayson-Pitts, B. J. A New GG-MS Experiment for the Undergraduate Instrumental Analysis Laboratory in Environmental Ghemistry Methyl-f-butyl Ether and Benzene in Gasoline, /. Chem. Educ. 1998,... 

Competitive metallation experiments with IV-methylpyrrole and thiophene and with IV-methylindole and benzo[6]thiophene indicate that the sulfur-containing heterocycles react more rapidly with H-butyllithium in ether. The comparative reactivity of thiophene and furan with butyllithium depends on the metallation conditions. In hexane, furan reacts more rapidly than thiophene but in ether, in the presence of tetramethylethylenediamine (TMEDA), the order of reactivity is reversed (77JCS(P1)887). Competitive metallation experiments have established that dibenzofuran is more easily lithiated than dibenzothiophene, which in turn is more easily lithiated than A-ethylcarbazole. These compounds lose the proton bound to carbon 4 in dibenzofuran and dibenzothiophene and the equivalent proton (bound to carbon 1) in the carbazole (64JOM(2)304). 

Direct proof of an oxaziridine intermediate was achieved in photolysis experiments in an organic glass at 77 K (80JA5643). Oxaziridine (75), formed by photolysis of A/-oxide (74) and evidenced by UV spectroscopy under the above conditions, decomposed at higher temperature to form the imino ether (76) by N—O bond cleavage and C -> O migration of an aryl group. 

Rate differences observed between the same bromophenylcarbene (241) when prepared by two different routes, diazirine photolysis and the reaction of benzylidene dibromide with potassium r-butoxide, vanish when a crown ether is added to the basic solution in the latter experiment. In this case the complexing potassium bromide is taken over by the crown ether, and selectivity towards alkenes reaches the values of the photolytic runs (74JA5632). 

The octyl hydrogen phthalate is filtered, washed with water, ground thoroughly with water in a mortar and finally filtered and dried. For complete purification it may be crystallized either from petroleum ether (b.p. 60-70°) or glacial acetic acid from which it separates as needles melting at 55°. The crude material, however, is perfectly satisfactory for the following experiments. The yield is nearly quantitative if the ec.-octyl alcohol is pure (Note 2). 

Scheme 10. Mechanislic possibililies for PF condensalion. Mechanism a involves an SN2-like attack of a phenolic ring on a methylol. This attack would be face-on. Such a mechanism is necessarily second-order. Mechanism b involves formation of a quinone methide intermediate and should be Hrst-order. The quinone methide should react with any nucleophile and should show ethers through both the phenolic and hydroxymethyl oxygens. Reaction c would not be likely in an alkaline solution and is probably illustrative of the mechanism for novolac condensation. The slow step should be formation of the benzyl carbocation. Therefore, this should be a first-order reaction also. Though carbocation formation responds to proton concentration, the effects of acidity will not usually be seen in the reaction kinetics in a given experiment because proton concentration will not vary.

In Pedersen s early experiments, the relative binding of cations by crown ethers was assessed by extraction of alkali metal picrates into an organic phase. In these experiments, the crown ether served to draw into the organic phase a colored molecule which was ordinarily insoluble in this medium. An extension and elaboration of this notion has been developed by Dix and Vdgtle and Nakamura, Takagi, and Ueno In efforts by both of these groups, crown ether molecules were appended to chromophoric or colored residues. Ion-selective extraction and interaction with the crown and/or chromophore could produce changes in the absorption spectrum. Examples of molecules so constructed are illustrated below as 7 7 and 18 from refs. 32 and 131, respectively. 

The processes used in the manufacture of morphine are believed to be still based on that described by the Scottish chemist Gregory,in 1833, with improvements devised by Anderson. A description has been published by Schwyzer, who also deals with the manufactme of codeine, narcotine, cotarnine, and the commercially important morphine derivatives, diamorphine (diacetylmorphine), and ethylmorphine (morphine ethyl ether). More recently Barbier has given an account of processes, based on long experience in the preparation of alkaloids from opium. Kanewskaja has described a process for morphine, narcotine, codeine, thebaine and papaverine, and the same bases are dealt with by Chemnitius, with the addition of narceine, by Busse and Busse, and by Dott. It is of interest to note that a number of processes for the extraction and separation of opium alkaloids have been protected by patent in Soviet Russia. ... 

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