Ethers and acidity

Materials of these types have T s of some 290-300°C and some grades are claimed to be stable to about 400°C. Whilst resistant to hydrocarbons, halogenated hydrocarbons, ethers and acids the polymers are soluble in such materials as dimethylformamide, N-methylpyrrolidone and pyridine. Bases can cause stress cracking. These non-crystalline polymers are tough at temperatures as low as -46°C whilst at 260°C they have the strength shown by PTFE at room temperature. The polymers also exhibit excellent electrical insulation properties. 

The use of silylated monomers is an interesting alternative method of aromatic polyester synthesis since the silylated gaseous by-products cannot participate in the reverse reaction, shifting polyesterification toward polymer formation. Reactions between silyl esters and acetates (Scheme 2.23) and reactions between silyl ethers and acid chlorides (Scheme 2.24) have been applied to the synthesis of linear265-267 and hyperbranched wholly aromatic polyesters202,268 269 (see Section 2.4.5.2.2). 

The BDEs of a-C—H bonds of alcoholic and acidic substituents are compared with those of ethers and acids. Both types of BDE of C—H bonds are lower than those of the hydrocarbons. 

Reduction of esters by trichlorosilane in tetrahydrofuran in the presence of tert-butyl peroxide and under ultraviolet irradiation gave predominantly ethers from esters of primary alcohols, while esters of tertiary alcohols were cleaved to acids and hydrocarbons. Esters of secondary alcohols gave mixtures of ethers and acids/hydrocarbons in varying ratios. 1-Adamantyl trimethylacetate, for example, afforded 50-100% yields of mixtures containing 2-42% of 1-adamantyl neopentyl ether and 58-98% of adamantane and trimethylacetic acid [1033]. 

Light-activated shift of double bonds in organic compounds can promote the reaction of oxygen with a molecule. Once oxygen has bonded to a fuel component, oxidized organic compounds such as alcohols, aldehydes, esters, ethers, and acids can form. These compounds can then continue to react with other fuel components to form color bodies, gums, and insoluble deposits. 

EtjN,663 and N,N -carbonyldiimidazole (100).664 In the latter case easily alcoholyzed im-idazolides (101) are intermediates. BF3 promotes the esterification by converting the acid to RCO+ BF3OH, so the reaction proceeds by an AacI type of mechanism. The use of BF etherate is simple and gives high yields.665 Carboxylic esters can also be prepared by treating carboxylic acids with /-butyl ethers and acid catalysts.666... 

The ether and acid layers are separated and the ether is evaporated. The residue is extracted with acetone to remove the grease and sulfur and the nitrocompds weighed... 

Table IV. Enthalpy Changes (kcal mol-1) for Reactions between Water, Diethyl Ether, and Acids (HA) and Ions (T)...

Olefinic alcohols, ethers, and acids have been prepared by this method. The nitro group is reduced to the amino group... 

Reaction of ethers and acid haSdes. Acyclic ethers, when refluxed neat or in hexane or isooctane solution with acid chlorides in the presence of molybdenum hexacarbonyl, give esters, organic chlorides, and, in some instances, alkenes. 

Epoxidation of the appropriate geranyl ether and acid hydrolysis to the corresponding glycol affords the natural products marmin (30) and severin... 

Reactions and Products. Ethers.—Being both alcohols and acids the hydroxy acids undergo reactions and yield products characteristic of both classes of compounds, (i) As acids they form metallic salts, acid chlorides and acid amides, which are exactly analogous to those formed from the acetic acid series both as to methods of formation and properties. These need not be discussed further. (2) They form ethers with other alcohols, in this case reacting as an alcohol. These new compounds will be mixed ether and acid compounds. 

Carboxylic esters can also be prepared by treating carboxylic acids with tert-butyl ethers and acid catalysts. 

If nitro compds are absent, the residue is treated with acetic acid to remove NG ("explosive oil. ) The grease is then separated from sulfur by creating with acetone, if nitrocompounds are present, only half of the ether-CS2 extract is used for detn of grease and sulfur, while the other half is treated, after evaporation of solvents, with methyl sulfuric acid to remove NG. The ether and acid layers are separated and the ether is evaporated. The residue is extracted with acetone to remove the grease and sulfur and the nittocompds weighed... 

The ability of calixarenes to bind large metal ions with high kinetic stability is important in the search for complexants for radionuclides such as Cs (ti/2 = 30.2 yr) and Sr (ti/2 = 65 d) from the reprocessing of exhausted nuclear fuel. There has been considerable interest in caesium-complexed calix[4]-bis-crowns as selective Cs-carriers. Transport isotherms of trace level Cs through supported liquid membranes containing calix[4]-bis-crowns have been determined as a function of the ionic concentration of the aqueous feeder solutions, and l,3-calix[4]-bis-o-benzo-crown-6 appears to be much more efficient in decontamination than mixtures of crown ethers and acidic exchangers, especially in highly acidic media. " ... 

Properties White powder, becomes yellowish with age. Deliquescent. D 3.359 mp 76C (decomposes). Soluble in water, alcohol, ether, and acid. 

Properties Brown, amorphous powder. Soluble in alcohol, ether, and acids insoluble in water. Combustible. 

Production of alpha-terpinyl alkyl ethers Beta Excellent yields in continuous reactor Eliminates use of HCl, H2SO4, AICI3, toluene, sulfonic acid, boron trifluoride etherate, and acidic cation resins as catalysts... 

Schultz s remarkable work combines ether and acid in the same molecule and adds a chiral... 

When polycarbonate is irradiated in the solid state, yellowing is confined almost exclusively to the surface, since the light intensity penetrating the sample decreases as the dose is increased. Change in carbonyl absorption and increase in hydroxyl contents have been detected together with formation of phenols, esters, ethers and acids, and evolution of carbon monoxide and dioxide [110]. Since crosslinking is associated with chain scission, a thin yellow film coming from the surface remains insoluble after dissolution of the irradiated sample in methylene chloride... 

Several ways to produce such a-terpinyl alkyl ethers are known, but limonene and a-pinene are the most used feedstock molecules (Figure 8). Alkoxylation of limonene and a-pinene over homogeneous or heterogeneous catalysts as, for example, strong acids FICl, H2SO4 or p-toluenesulfonic acid, aluminium trichloride and boron trifluoride etherate and acidic cation exchange resin has... 

Astaxanthin (403) can be obtained from 380 by two routes, in both of which the bis-enolate 47 is produced by reaction with lithium diisopropylamide or sodium hexamethyl-disilazane. In the first method, 47 is converted into the bis-silyl enol ether (48) which, after oxidation with peroxyacids, rearrangement to give the astaxanthin bis-silyl ether and acid-catalysed cleavage of the silyl groups, yields free 403 [31]. Alternatively, 47 can be oxidized directly to 403 by reaction with l-phenylsulphonyl-2-phenyloxaziridine [32] (Scheme 10). 

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