Water dimethyl ether

Ethers are organic compounds structurally related to alcohols. The oxygen atom in an ether group, however, is bonded not to a carbon and a hydrogen but rather to two carbons. As we see in Figure 12.14, ethanol and dimethyl ether have the same chemical formula, C2H(50, but their physical properties are vastly different. Whereas ethanol is a liquid at room temperature (boiling point 78°C) and mixes quite well with water, dimethyl ether is a gas at room temperature (boiling point —25°C) and is much less soluble in water. 

Solubihty soluble in acetone, chloroform, ethanol (95%), ether, and 1 in 3 parts of water. Dimethyl ether is generally miscible with water, nonpolar materials, and some semi-polar materials. For pharmaceutical aerosols, ethanol (95%) is the most useful cosolvent. Glycols, oils, and other similar materials exhibit varying degrees of miscibility with dimethyl ether. 

The crude methanol that is produced by the low-pressure process contains water, dimethyl ether, esters, ketones, iron carbonyl, and higher alcohols. However, these impurities, although similar to those formed in the high-pressure process, were much less in quantity. 

Fig. 2 Temperature-composition diagram for the water-dimethyl ether system. The two hydrates that form at -12 and 22 Wt% DME are Structure II (DME,17H 0) and Structure T (DME.8 2/3 H2O hydrates, respectively), Both decompose in-congruently. (S.L. Miller, S.R. Gough, D.W. Davidson. J. Phys. Chem. 1977. 81, 2154 K.A. Udachin. C.I. Ratcliffe. and J.A. Ripmeester, Angew. Chem. Int. Ed. 2001. 113. 1343.)...

Ethanol has a melting point of-117.3°C, a boiling point of +78.5°C, and is miscible with water. Dimethyl ether has a melting point of-138.5°C, a boiling point of-25°C (it is a gas at room temperatnre), and dissolves in water to the extent of 37 volumes of gas to one volnme of water. 

Rationalize the differences between the following dipole moments for water, dimethyl ether, and ethylene oxide (oxirane) ... 

Water. Dimethyl Ether, Alcohols and Carboxylic Acids. We have reported that SI reacts rapidly with molecules containing hydroxyl groups to abstract the hydroxyl group (7) ... 

Di-alkyl ethers of ethylene glycol, ROCHjCHjOR. The dimethyl ether, b.p. 85°/760 mm., is miscible with water, is a good solvent for organic compounds, and is an excellent inert reaction medium. The diethyl ether (diethyl cdloaolve), b.p. 121-57760 mm., is partially miscible with water (21 per cent, at 20°). 

Use Learning By Modeling to make models of water methanol dimethyl ether and di tert butyl ether Mini mize their geometries and examine what happens to the C—O—C bond angle Compare the C—O bond dis tances in dimethyl ether and di tert butyl ether... 

The unit has virtually the same flow sheet (see Fig. 2) as that of methanol carbonylation to acetic acid (qv). Any water present in the methyl acetate feed is destroyed by recycle anhydride. Water impairs the catalyst. Carbonylation occurs in a sparged reactor, fitted with baffles to diminish entrainment of the catalyst-rich Hquid. Carbon monoxide is introduced at about 15—18 MPa from centrifugal, multistage compressors. Gaseous dimethyl ether from the reactor is recycled with the CO and occasional injections of methyl iodide and methyl acetate may be introduced. Near the end of the life of a catalyst charge, additional rhodium chloride, with or without a ligand, can be put into the system to increase anhydride production based on net noble metal introduced. The reaction is exothermic, thus no heat need be added and surplus heat can be recovered as low pressure steam. 

Other Propellants. Dimethyl ether (DME) [115-10-6] is finding use as an aerosol propeUant. DME is soluble in water, as shown in Table 5. Although this solubiHty reduces DME s vapor pressure in aqueous systems, the total aerosol solvent content may be lowered by using DME as a propeUant. The chief disadvantage is that DME is flammable and must be handled with caution. 

Fig. 5. Methanol-to-hydrocarbons reaction path at 371°C, where (A ) is methanol ( ), dimethyl ether (), water (D), paraffins (and Cg...

Neopentyl glycol, or 2,2-dimethyl-1,3-propanediol [126-30-7] (1) is a white crystalline soHd at room temperature, soluble ia water, alcohols, ethers, ketones, and toluene but relatively iasoluble ia alkanes (1). Two primary hydroxyl groups are provided by the 1,3-diol stmcture, making this glycol highly reactive as a chemical intermediate. The gem-A methy configuration is responsible for the exceptional hydrolytic, thermal, and uv stabiUty of neopentyl glycol derivatives. 

Methanol can be dehydrated over an acidic catalyst to give dimethyl ether and water ... 

Water is also formed in the acid cataly2ed dehydration of methanol to give dimethyl ether. The solution is acidic because of the presence of the HI. 

Liquid mixtures of methanol and hydrochloric acid slowly yield methyl chloride even at 0°C (20,21), The typical process is carried out by contacting the alcohol with hydrochloric acid at 70 to 160°C and 0.1—1 MPa (15—150 psig) in the presence of a catalyst such as zinc chloride, quaternary amines (18,19,22), or with no catalyst at aH (23,24). TypicaHy 0.5 to 3% of the methanol is converted to dimethyl ether. Product methyl chloride is taken out of the reactor as a vapor and is cooled to condense as much of the water vapor and HCl as possible. Dimethyl ether and the residual water is then removed and the finished methyl chloride is condensed. 

Methanol to Ethylene. Methanol to ethylene economics track the economics of methane to ethylene. Methanol to gasoline has been flilly developed and, during this development, specific catalysts to produce ethylene were discovered. The economics of this process have been discussed, and a catalyst (Ni/SAPO 34) with almost 95% selectivity to ethylene has been claimed (99). Methanol is converted to dimethyl ether, which decomposes to ethylene and water the method of preparation of the catalyst rather than the active ingredient of the catalyst has made the significant improvement in yield (100). By optimizing the catalyst and process conditions, it is claimed that yields of ethylene, propylene, or both are maximized. This is still in the bench-scale stage. 

Tetrahydrofuran may be purified by refluxing over solid potassium hydroxide, followed by distillation from lithium alu-miniun hydride. Tetrahydrofuran may be replaced by ethylene glycol dimethyl ether (dimethoxyethane). The submitter has indicated that either solvent may be freed conveniently from water, alcohols, and moderate amounts of peroxides by passing the commercial solvent through a column (2 in. diameter X 2-3 ft. length) of Linde Air Products Molecular Sieves (type 13A iQ- n. pellets), at a rate of approximately 100 ml. per minute. 

A solution of cholest-4-en-3-one (139), 1 g, in diethylene glycol dimethyl ether (20 ml) is treated for 1 hr with a large excess of diborane at room temperature under nitrogen and then left for a further 40 min. Acetic anhydride (10 ml) is added and the solution refluxed for 1 hr. The mixture is concentrated to a small volume, diluted with water and extracted with ether. The extracts are washed with 10% sodium hydroxide solution, then with water and dried over sodium sulfate. Removal of the solvent leaves a brown oil (1.06 g) which is purified by chromatography on alumina (activity I). Hexane elutes the title compound (141), 0.68 g mp 76-77°. Successive crystallization from acetone-methanol yields material mp 78-79°, [a]p 66°. 

The reaction mixture is evaporated to a small volume, whereupon the d-tubocurarine dimethyl ether iodide precipitates. The precipitate is filtered off and dissolved in boiling water. The hot solution is treated with a small amount of decolorizing carbon, the carbon filtered off and the filtrate cooled to about 0°C. The dimethyl ether of d-tubocurarine iodide crystallizes in white crystals which melt at about 267°-270°C with decomposition. 

A mixture consisting of 22.7 g potassium o-bromobenzoate, 16.6 g 2,6-dichloro-3-methvlani-line, 12 ml N-ethylmorpholine, 60 ml diethylene glycol dimethyl ether, and 1.0 g anhydrous cupric bromide is heated in a nitrogen atmosphere at 145 C to 155°C for 2 hours. The reaction mixture is diluted with 60 ml diethylene glycol dimethyl ether and acidified with 25 ml concentrated hydrochloric acid. The acidic mixture is diluted with 100 ml of water and the liquid phase decanted from the insoluble oil. The insoluble oil is stirred with methanol and the crystalline N-(2,6-dichloro-3-methylphenyl)anthranilic acid which separates is collected and washed with methanol. The product, after recrystallization from acetone-water mixture melts at 248 C to 250°C. 

C) Preparation of 2-Methyl-3-(2,2,2-Trifluoroethyl)Thiomethyl-6-Chloro-7-Sulfamyl-3,4-Dihydro-1,2,4-Benzothiadiazine-1,1-Dioxide To 4.6 g (0.015 mol) of 4-amino-2-chloro-5-(methylsulfamyl)benzenesulfonamide in 30 ml of the dimethyl ether of ethylene glycol is added 4.08 g (0.02 mol) of 2,2,2-trifluoroethylmercaptoacetaldehyde dimethylacetal followed by 1 ml of ethyl acetate saturated with hydrogen chloride gas. The resulting solution is refluxed for 1.5 hours, cooled and then slowly added to cold water dropwise with stirring. The crude product is filtered, dried and recrystallized from isopropanol (3.2 g), MP 202° to 202.5°C. A second recrystallization from isopropanol raised the MP to 202°... 

The reaction occurs in the liquid phase at relatively low temperatures (about 50°C) in the presence of a solid acid catalyst. Few side reactions occur such as the hydration of isohutene to tertiary hutyl alcohol, and methanol dehydration and formation of dimethyl ether and water. However, only small amounts of these compounds are produced. Figure 5-8 is a simplified flow diagram of the BP Etherol process. 

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