Uses for Ethers

INDUSTRIAL USES FOR ETHERS A. Dialkyl and Alkyl Vinyl Ethers 

Dimethyl ether is used as a solvent in aerosol formulations. Diethyl ether as a commercial product is available in several grades and is used as an extraction solvent, reaction solvent, and as a general anesthetic. Ethyl ether is an excellent solvent for alkaloids, dyes, fats, gums, oils, resins, and waxes. Blends of ethyl ether and ethanol are excellent solvents for cellulose nitrate used in the manufacture of guncotton, in collodion solutions and pyroxylin plastics. Ethyl ether is used in the recovery of acetic acid from aqueous solutions in the cellulose acetate and plastic industry. It is used as a starter fuel for diesel engines and as a denaturant in denatured ethanol formulations. Grignard and Wurtz-Fillig synthesis reactions use diethyl ether as an anhydrous, inert reaction medium. 

3- Dioxolane is used to dissolve a wide spectrum of polymeric materials such as acrylates, alkyds, cellulosics, epoxys, polycarbonates, polyesters, urethanes, and vinyl resins. In many cases, 1,3-dioxolane solvent can replace the chlorinated solvents that were used previously to dissolve many of these polymers. The excellent solvency of 1,3-dioxolane for polymeric compositions makes this cyclic ether a valuable component in paint remover formulations. 

4- Dioxane, the six-member cyclic diether, is used as an aluminum inhibitor in chlorinated solvents like 1,1,1-trichloroethane and as a solvent for certain resins and polymers. 

Propylene oxide and 1,2-butylene oxide cyclic ethers find their largest use as chemical intermediates. Both oxides react readily with dilute amounts of mineral acids (e.g., hydrochloric acid) to form the chlorohydrin addition product. This reactivity with acid make these epoxy solvents valuable acid acceptor-type stabilizers for several chlorinated solvents. Trace amounts of hydrogen chloride from chlorinated solvent degradation is immediately neutralized by reaction with the propylene or 1,2-butylene oxide stabilizer. Reaction of propylene oxide with an alcohol or phenol in the presence of an acid catalyst yields the monoether of propylene glycol (see Chapter 13 for the glycol ethers). 

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B) Picrates. Very useful for ethers containing an aromatic group. 

Two sets of fi and g are given in the article for each second-order group to cover both upper (u) and lower (/) hmits (z) in volume percent units. A study of this method for about 80 organic compounds in 14 famihes shows absolute errors of 0.15 percent and 2.3 percent for the lower and upper hmits, respectively. The upper limit predic tion should not be used for ethers. 

Sulfides are the sulfur analogs of ethers just as thiols are the sulfur analogs of alcohols. Sulfides are named by following the same rules used for ethers, with sulfide used in place of ether for simple compounds and alkylthio used in place of alkoxy for more complex substances. 

In comparison with other anionics, little has been published concerning methods of analysis of ether carboxylates. Gerhardt et al. [238] investigated the analytical determination of ether carboxylic acids in reaction mixtures obtained by reaction of nonylphenol ethoxylates with sodium chloroacetate as well as by cyanoethylation by different methods. Several methods, used for other surfactants as well [239], can be used for ether carboxylates. 

BF3 is also used for ether carbon-oxygen cleavage in the presence of sulfide or thiol (Scheme 62). 

Ethers can be cleaved under strongly acidic conditions by intermediate formation of dialkyloxonium salts. Hydrobromic and hydroiodic acids are especially useful for ether cleavage because both are strong acids and their anions are good nucleophiles. Tertiary alkyl ethers are very easily cleaved by acid reagents ... 

Unsymmetrical sulfides 39 need the same disconnection we have just used for ethers. The anion 41 of a thiol 42 will combine with an alkyl halide 40 to make a new C-S bond. The reaction is much easier with sulfur. Thiols are more acidic than alcohols, just as H2S is more acidic than water. Sulfide anions 41 are more nucleophilic towards saturated carbon than are alkoxides and the risk of elimination is much less. 

Amine synthesis needs a separate chapter because the C-X disconnection la used for ethers, sulfides and the like in chapter 4 is not suitable for amines. The problem is that the product of the first alkylation 2 is at least as nucleophilic as the starting material 1 (if not more so because of the electron-donating effect of each alkyl group) and further alkylation occurs giving the tertiary amine 3 or even the quaternary ammonium salt 4. It is no use adding just one equivalent of Mel as the first formed product 1 will compete with the starting material 2 for Mel. 

Although early reports suggested that iridium complexes were ineffective catalysts for the hydroboration reaction, subsequent work has shown that Crabtree s catalyst (see Crabtree s Catalyst), [Ir(cod)(py)(PCy3)] PFe, can be used for ether or amide-directed hydroborations. For instance, iridium catalyzed hydroborations of pyrrolidinyl amides with HBcat gave syn 1,3-hydroxyl amides with high levels of regio- and stereocontrol (equation 5). In contrast, reactions... 

Disposal of flammable solvents in storm sewers or sanitary sewers is, in general, not allowed. Exceptions are small amounts of those materials that are miscible with water, but even disposal of these should be followed by large amounts of cold water. Other solvents should be collected in safety cans. Separate cans should be used for ether and for chlorinated solvents all other solvents may be combined in a third can. The cans should be stored, in keeping with storage quantity rules, in a safety cabinet until pickup by a waste-disposal firm. A more economical approach is to transfer the solvents to larger cans or drums in an outside storage facility so that pickup could be less frequent. Some large institutions have their own in-house disposal facilities. 

Three kinds of ethers are known (1) aliphatic, (2) aromatic, and (3) mixed. Common names are used for ethers in most cases. 

Anhydrous sulfonic acids such as / -toluenesulfonic and methanesulfonic acid are very useful for ether fission according to the equation 17... 

Used for ethers and other compounds which tend to react with air or oxygen to form peroxides. Examples diethyl ether, dioxan, and tetrahydrofuran. 

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