Alcohols dehydration ethanol

Membranes becoming more widely available for aqueous—organic separations some successful industrial appHcations reported for dehydrations and removal of alcohols (ethanol and above) from water. 

Alcohols undergo dehydration in supercritical and hot water (41). Tertiary alcohols require no catalyst, but secondary and primary alcohols require an acid catalyst. With 0.01 MH2SO4 as a catalyst, ethanol eliminates water at 385°C and 34.5 MPa to form ethene. Reaction occurs in tens of seconds. Only a small amount of diethyl ether forms as a side reaction. 

Alcohols undergo dehydration in the presence of protic acids (H2SO4, H3PO4). The formation of the reaction product, alkene or ether depends on the reaction conditions. For example, ethanol is dehydrated to ethene in the presence of sulphuric acid at 443 K. At 413 K, ethoxyethane is the main product. 

CA) and ethanol (Dehydrated Alcohol, USP Pinctillians, US Industrial Chemical Co., Tuscola, IL) were used to prepare solvent mixtures for all the experiments. 

The information about synthetic mordenite properties was obtained in 1961 when Keough and Sand (7) found that H- and other forms of this crystalline aluminum silicate display high activity and selectivity in the reactions of hydrocarbon cracking and ethanol dehydration. Later this zeolite was shown (J, 2, 5, 7, 8, 10-13, 15, 16) an active catalyst in the reactions of isomerization, cracking, and alkylation of hydrocarbons and alcohol dehydration. However, the catalytic properties of mordenite have been studied insufEciently, compared with those of other zeolites. 

Note the above typical properties are for alcohol (ethanol 95% or 96% v/v). See Section 17 for typical properties of dehydrated alcohol. 

Ethanol/ Dehydrated Alcohol/ Alcohol Azmacort, Isuprel, Primatene Mist, Tornalate, Qvar, Atrovent HFA, Proventil HFA, Xopenex HFA, Aerospan HFA, Alvesco Co-solvent 34.5%... 

Isopropyl alcohol is dehydrated to propylene and water by the same type of catalysts that are effective with ethanol. Because of the higher original molecular weight of the alcohol, however, somewhat more complex decompositions are possible, especially at excessively high temperatures or in the presence of very active catalysts. At temperatures of 300° to 350° C. the main products are propylene and water when active dehydrating catalysts as alumina, titania, or clay are used.87- i, v- ... 

Packaging Rectified spirit (96% ethanol by volume) is marketed directly for the manufacture of chemicals such as acetic acid, acetone, oxalic acid and absolute alcohol. Denatured ethanol for industrial and laboratory use typically contains 60-95% ethanol as well as between 1% and 5% each of methanol, isopropanol, methyl isobutyl ketone (MIBK), ethyl acetate and so forth. For beverages, the alcohol is matured and blended with malt alcohol (for manufacture of whisky) and diluted to requisite strength to obtain the desired type of liquor. This is bottled appropriately in a bottling plant. Anhydrous ethanol for fuelblending applications (power alcohol) requires concentration of the ethanol to 99.5 wt% purity. The ethanol dehydration is typically done using molecular sieves. 

Diethyl ether and several other commercially available ethers are synthesized on an industrial scale by the acid-catalyzed dehydration of primary alcohols. Intermolecular dehydration of ethanol, for example, gives diethyl ether. 

Drug release systems, synthetic articular cartilages, ultrafiltration membranes pH-sensitive bio-actuators/sensors drug delivery devices materials for the dehydration process of alcohols, ethanol or methanol organic memory devices separation of organic solute molecules from water or electrolyte membranes for fuel cell applications... 

Building on the proposed mechanism hy Hauffe, ° for metal oxide-catalysed dehydration of alcohols to form olefins, ethers and water which heavily relies on the assumption that the catalyst surface acts as semiconductor, Hasssan et al. purposively attempted to obtain a further insight into the mechanism of alcohol dehydration on pure cadmium oxide. On the basis of the experimental data involving kinetics of the dehydration reaction and the effect of pretreatment of the catalysts along with studies on lattice structure and specific surface areas, a mechanism for ethanol dehydration was put forward (Scheme 17.14). The proposed mechanism entirely depends... 

Dehydration of secondary alcohols usually occurs by El, but it can occur by E2. Ethanol, a primary alcohol, undergoes dehydration by a concerted E2 reaction, as shown below ... 

CHa CHlCH CHO. Colourless lachrymatory liquid with a pungent odour. B.p. 104 "C. Manufactured by the thermal dehydration of aldol. May be oxidized to crotonic acid and reduced to crolonyl alcohol and 1-butanol oxidized by oxygen in the presence of VjOj to maleic anhydride. It is an intermediate in the production of l-butanol from ethanol. 

Directly from the corresponding acid and alcohol, in the presence of a dehydrating agent. Thus when ethanol and acetic acid are mixed, ethyl acetate and water are formed, but in addition an equilibrium is established. 

Trifluoromethanesulfonic acid is miscible in all proportions with water and is soluble in many polar organic solvents such as dimethylformamide, dimethyl sulfoxide, and acetonitrile. In addition, it is soluble in alcohols, ketones, ethers, and esters, but these generally are not suitably inert solvents. The acid reacts with ethyl ether to give a colorless, Hquid oxonium complex, which on further heating gives the ethyl ester and ethylene. Reaction with ethanol gives the ester, but in addition dehydration and ether formation occurs. 

Bisa.codyl, 4,4 -(2-PyridyLmethylene)bisphenol diacetate [603-50-9] (Dulcolax) (9) is a white to off-white crystalline powder ia which particles of 50 p.m dia predominate. It is very soluble ia water, freely soluble ia chloroform and alcohol, soluble ia methanol and ben2ene, and slightly soluble ia diethyl ether. Bisacodyl may be prepared from 2-pyridine-carboxaldehyde by condensation with phenol and the aid of a dehydrant such as sulfuric acid. The resulting 4,4 -(pyridyLmethylene)diphenol is esterified by treatment with acetic anhydride and anhydrous sodium acetate. Crystallisation is from ethanol. 

The hydroperoxide process involves oxidation of propjiene (qv) to propylene oxide by an organic hydroperoxide. An alcohol is produced as a coproduct. Two different hydroperoxides are used commercially that result in / fZ-butanol or 1-phenylethanol as the coproduct. The / fZ-butanol (TBA) has been used as a gasoline additive, dehydrated to isobutjiene, and used as feedstock to produce methyl tert-huty ether (MTBE), a gasoline additive. The 1-phenyl ethanol is dehydrated to styrene. ARCO Chemical has plants producing the TBA coproduct in the United States, Erance, and the Netherlands. Texaco has a TBA coproduct plant in the United States. Styrene coproduct plants are operated by ARCO Chemical in the United States and Japan, Shell in the Netherlands, Repsol in Spain, and Yukong in South Korea. 

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