Ethere analysis

Mole ratio amino alcohol LAH = 4.1 1.8. Reaction carried out at - 70°C with insoluble, freshly prepared complexes in ether. Analysis by GC of MTPA ester derivatives. 

Haggard, H. W. (1924). The absorption, distribution and elimination of ethyl ether. Analysis of the mechanism of the absorption and elimination of such a gas or vapor as ethyl ether. J Biol Chem 59, 753-770. 

M) in pyridine (7 mL) for 24 h at 25°C. The carboxylic derivative is then washed with methanol (four times) and ether. Analysis for the extent of carboxylation involves a two-step procedure. An accurately weighed aliquot is treated with DCC and p-nitrophenol in pyridine. After several washings with THF to remove uiu eacted p-nitrophenol, piperidine-pyridine (1 9) is added to the silica gel, and the amount of p-nitrophenol released is measured at A = 410 nm by using 1.57 X lO" cm as the extinction coefficient of p-nitrophenoxide. The incorporation of carboxylic acid is 200 /u-mol/g. 

Individual compounds in air, water, or wastes may be analyzed by common instrumental techniques such as gas chromatography using a flame ionization detector. Other techniques, such as HPLC and GC/MS, are equally suitable. Any column that is efficient for the separation of alcohols may be used to analyze glycol ethers. Analysis of some of these compounds is discussed in greater detail in the sections on individual compounds. 

Catchpole, O. J., Grey, J. B. Perry, N. B., et al.. Extraction of chiU, black pepper and ginger with near critical CO2, propane and dimethyl ether analysis of the extracts by quantitative nuelear magnetic resonance, J. Agric. Food. Chem. (2003) 51(17), 4853-4860. 

New Method for Blood Ether Analysis Fifth Annual Gas Chromatogr. Inst.,... 

Piazza, F. Barbieri, A. Saverio Violante, F. and Roda, A. A rapid and sensitive method for methyl tert-butyl ether analysis in water samples by use of solid phase microextraction and gas chromatography-mass spectrometry. Chemosphere 2001,44 (4), 539-544. 

Beste A, Buchanan III AC. Computational investigation of the pyrolysis product selectivity for a-hydroxy phenethyl phenyl ether and phenethyl phenyl ether analysis of substituent effects and reactant conformer selection. J Phys Chem A. 2013 117 3235—3242. 

Absolute diethyl ether. The chief impurities in commercial ether (sp. gr. 0- 720) are water, ethyl alcohol, and, in samples which have been exposed to the air and light for some time, ethyl peroxide. The presence of peroxides may be detected either by the liberation of iodine (brown colouration or blue colouration with starch solution) when a small sample is shaken with an equal volume of 2 per cent, potassium iodide solution and a few drops of dilute hydrochloric acid, or by carrying out the perchromio acid test of inorganic analysis with potassium dichromate solution acidified with dilute sulphuric acid. The peroxides may be removed by shaking with a concentrated solution of a ferrous salt, say, 6-10 g. of ferrous salt (s 10-20 ml. of the prepared concentrated solution) to 1 litre of ether. The concentrated solution of ferrous salt is prepared either from 60 g. of crystallised ferrous sulphate, 6 ml. of concentrated sulphuric acid and 110 ml. of water or from 100 g. of crystallised ferrous chloride, 42 ml. of concentrated hydiochloric acid and 85 ml. of water. Peroxides may also be removed by shaking with an aqueous solution of sodium sulphite (for the removal with stannous chloride, see Section VI,12). 

CAUTION. Ethers that have been stored for long periods, particularly in partly-filled bottles, frequently contain small quantities of highly explosive peroxides. The presence of peroxides may be detected either by the per-chromic acid test of qualitative inorganic analysis (addition of an acidified solution of potassium dichromate) or by the liberation of iodine from acidified potassium iodide solution (compare Section 11,47,7). The peroxides are nonvolatile and may accumulate in the flask during the distillation of the ether the residue is explosive and may detonate, when distilled, with sufficient violence to shatter the apparatus and cause serious personal injury. If peroxides are found, they must first be removed by treatment with acidified ferrous sulphate solution (Section 11,47,7) or with sodium sulphite solution or with stannous chloride solution (Section VI, 12). The common extraction solvents diethyl ether and di-tso-propyl ether are particularly prone to the formation of peroxides. 

Analysis There are four ether groups, but they are peripheral and easily made. The key FG is the amide which we must discoimect first at the C-N bond. Both acid and amine could be made from the same nitrile. 

Analysis The cychc ether is obviously made from a diol, and that gives us a 1,2-dioxygenated skeleton of the right kind ... 

Analysis The ether linkage can be disconnected directly on the alkyl side ... 

Analysis We must first decide whether to disconnect the ether ring or the a,p-imsaturated aldehyde. No doubt reasonable routes could be produced for both, but 1 shall give one only ... 

Analysis The cycHc ether can clearly be made from the open-chain diol ... 

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. ... 

The most stable protected alcohol derivatives are the methyl ethers. These are often employed in carbohydrate chemistry and can be made with dimethyl sulfate in the presence of aqueous sodium or barium hydroxides in DMF or DMSO. Simple ethers may be cleaved by treatment with BCI3 or BBr, but generally methyl ethers are too stable to be used for routine protection of alcohols. They are more useful as volatile derivatives in gas-chromatographic and mass-spectrometric analyses. So the most labile (trimethylsilyl ether) and the most stable (methyl ether) alcohol derivatives are useful in analysis, but in synthesis they can be used only in exceptional cases. In synthesis, easily accessible intermediates of medium stability are most helpful. 

Several standard methods for the quantitative analysis of food samples are based on measuring the sample s mass following a selective solvent extraction. For example, the crude fat content in chocolate can be determined by extracting with ether for 16 h in a Soxhlet extractor. After the extraction is complete, the ether is allowed to evaporate, and the residue is weighed after drying at 100 °C. This analysis has also been accomplished indirectly by weighing a sample before and after extracting with supercritical GO2. 

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,... 

Chlorine and bromine add vigorously, giving, with proper control, high yields of 1,2-dihaloethyl ethers (224). In the presence of an alcohol, halogens add as hypohaUtes, which give 2-haloacetals (225,226). With methanol and iodine this is used as a method of quantitative analysis, titrating unconsumed iodine with standard thiosulfate solution (227). 

Quantitative Analysis of All llithium Initiator Solutions. Solutions of alkyUithium compounds frequentiy show turbidity associated with the formation of lithium alkoxides by oxidation reactions or lithium hydroxide by reaction with moisture. Although these species contribute to the total basicity of the solution as determined by simple acid titration, they do not react with allyhc and henzylic chlorides or ethylene dibromide rapidly in ether solvents. This difference is the basis for the double titration method of determining the amount of active carbon-bound lithium reagent in a given sample (55,56). Thus the amount of carbon-bound lithium is calculated from the difference between the total amount of base determined by acid titration and the amount of base remaining after the solution reacts with either benzyl chloride, allyl chloride, or ethylene dibromide. 

The standard methods (26) of analysis for commercial lecithin, as embodied in the Official and Tentative Methods of the American Oil Chemists Society (AOCS), generally are used in the technical evaluation of lecithin (27). Eor example, the AOCS Ja 4-46 method determines the acetone-insoluble matter under the conditions of the test, free from sand, meal, and other petroleum ether-insoluble material. The phosphoHpids are included in the acetone-insoluble fraction. The substances insoluble in hexane are determined by method AOCS Ja 3-87. 

Of the 10 constituents which represent nearly half the oil of neroH, only linalool (10) can be said to contribute direcdy to the characteristic aroma of orange flower oil. In 1977, IFF chemists performed an in-depth analysis of this oil and identified three simple terpenic compounds, each present at less than 0.01%, a-terpenyl methyl ether [1457-68-0] (31), geranyl methyl ether [2565-82-4] (32), andhnalyl methyl ether [60763-44-2] (33) (11). The latter two compounds possess green floral-citms aromas and have been known to perfumery for some time a-terpenyl methyl ether (31) has been called the orange flower ether by IFF chemists owing to its characteristic odor. 

Dialkyl peroxides can be reduced to the corresponding alcohols and/or ethers using a variety of reducing agents, some of which, eg, hydriodic acid, have been used for analysis. 

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