Ethylene hydration with sulfuric acid

For separation of the olefins, reliance was placed largely on efficient fractional distillation under pressure, using techniques now familiar to the petroleum industry the unusual feature was the low temperature required for concentration of ethylene. The main olefin reactions developed were hydration with sulfuric acid to give the alcohol, which was then dehydrogenated to the corresponding aldehyde or ketone, and conversion to the olefin oxide by reaction with hypochlorous acid. The ready commercial availability of the olefin oxides led to a continuous stream of new products, such as glycols, glycol ethers, and alkanolamines. 

Industrial ethyl alcohol is produced from petrochemicals. The traditional process involved the hydration of ethylene with sulfuric acid to ethyl sulfate followed by hydrolysis to ethyl alcohol ... 

Ethanol, CH3CH2OH, is grain alcohol, which is found in alcoholic beverages. It is easily produced by the fermentation of the juices of sugarcane or other materials that contain natural sugars. The industrial method involves the hydration of ethylene with sulfuric acid catalyst (similar to reaction 26.9). 

Synthetic ethyl alcohol (known as ethanol to differentiate it from fermentation alcohol) was originally produced hy the indirect hydration of ethylene in the presence of concentrated sulfuric acid. The formed mono-and diethyl sulfates are hydrolyzed with water to ethanol and sulfuric acid, which is regenerated ... 

As it was not known what kind of organic matter acts as the major ligand for chromium in seawater, Nakayama et al. [38] used ethylene diaminetetra-acetic acid (EDTA) and 8-quinolinol-4-sulfuric acid to examine the collection and decomposition of organic chromium species, because these ligands form quite stable water-soluble complexes with chromium (III), although they are not actually present in seawater. Both of these chromium (III) chelates are stable in seawater at pH 8.1 and are hardly collected with either of the hydrated oxides. The organic chromium species were then decomposed to inorganic... 

Hydration of Olefins. The earliest and still the largest production of chemicals from petroleum hydrocarbons was based on the hydration of olefins to produce alcohols by the employment of sulfuric acid. The addition of olefins to sulfuric acid to form alkyl sulfates and dialkyl sulfates takes place on simple contact of the hydrocarbons with the acid. To keep down polymerization and isomerization of the hydrocarbons, the temperature is kept relatively low, usually below 40° C. and commonly considerably lower than that (18). The strength of the sulfuric acid used depends on the olefin to be absorbed. Absorption of ethylene requires an acid concentration higher than 90%, whereas propylene and butylenes are readily absorbed in 85% acid or less. The alkyl and dialkyl sulfate solutions, on dilution and heating, are hydrolyzed to the alcohols plus small amounts of by-product ethers. After distilling off the organic products, the dilute sulfuric acid is reconcentrated and re-used. 

This process allows the purification of glycols without the difficulties of salt separation because the manufacturing procedure is done in two discrete steps with ethylene oxide distillation prior to hydrolysis. The hydration step is either uncatalyzed at high temperatures and pressures or utilizes an acid catalyst. A U.S. Industrial Chemicals, Inc. process uses a sulfuric acid catalyst at moderate temperatures producing an aqueous solution of glycol-containing acid (9). This process requires an additional step in the purification to remove the catalyst. 

Biochemical reactions often involve addition to C = C bonds that are not conjugated with a true carbonyl group but with die poorer electron acceptor - COO. While held on an enzyme a carboxylate group may be protonated, making it a better electron acceptor. Nevertheless, there has been some doubt as to whether the carbanion mechanism of Eq. 13-6 holds for these enzymes. Some experimental data suggested a quite different mechanism, one that has been established for the nonenzymatic hydration of alkenes. An example is the hydration of ethylene by hot water with dilute sulfuric acid as a catalyst (Eq. 13-11), an industrial method of preparation of ethanol. The electrons of the double bond form the point of attack by a proton, and the resulting carbocation readily abstracts a hydroxyl... 

Traditionally, ethanol has been made from ethylene by sulfation followed by hydrolysis of the ethyl sulfate so produced. This type of process has the disadvantages of severe corrosion problems, the requirement for sulfuric acid reconcentration, and loss of yield caused by ethyl ether formation. Recently a successful direct catalytic hydration of ethylene has been accomplished on a commercial scale. This process, developed by Veba-Chemie in Germany, uses a fixed bed catalytic reaction system. Although direct hydration plants have been operated by Shell Chemical and Texas Eastman, Veba claims technical and economic superiority because of new catalyst developments. Because of its economic superiority, it is now replacing the sulfuric acid based process and has been licensed to British Petroleum in the United Kingdom, Publicker Industries in the United States, and others. By including ethanol dehydrogenation facilities, Veba claims that acetaldehyde can be produced indirectly from ethylene by this combined process at costs competitive with the catalytic oxidation of ethylene. 

Addition of Water Alkenes don t react with pure water, but in the presence of a strong acid catalyst such as sulfuric acid, a hydration reaction takes place to yield an alcohol. An -H from water adds to one carbon, and an -OH adds to the other. For example, nearly 300 million gallons of ethyl alcohol (ethanol) are produced each year in the United States by the acid-catalyzed addition of water to ethylene ... 

The reaction chemistry of simple organic molecules in supercritical (SC) water can be described by heterolytic (ionic) mechanisms when the ion product 1 of the SC water exceeds 10" and by homolytic (free radical) mechanisms when <<10 1 . For example, in SC water with Kw>10-11 ethanol undergoes rapid dehydration to ethylene in the presence of dilute Arrhenius acids, such as 0.01M sulfuric acid and 1.0M acetic acid. Similarly, 1,3 dioxolane undergoes very rapid and selective hydration in SC water, producing ethylene glycol and formaldehyde without catalysts. In SC methanol the decomposition of 1,3 dioxolane yields 2 methoxyethanol, il lustrating the role of the solvent medium in the heterolytic reaction mechanism. Under conditions where K klO"11 the dehydration of ethanol to ethylene is not catalyzed by Arrhenius acids. Instead, the decomposition products include a variety of hydrocarbons and carbon oxides. 

The hydration of olefins to alcohols has been carried out on a large scale by hydrolyzing the sulfuric acid esters formed by the absorption of the olefins in sulfuric acid. In the case of the higher olefins these reactions occur with comparative ease. Thus, isobutylene may be hydrated to tertiary butanol in cold, moderately concentrated sulfuric acid.81 Some of the pentenes and heptenes may be hydrated in dilute (5 to 10 per cent) solutions of formic, acetic, or oxalic acids as well as in weak solutions of the mineral acids.83 With 60 per cent concentrations of hydroiodic acid, isobutylene yields the iodide almost exclusively, but at lower concentrations increasing amounts of the alcohol are fonned84 Similar phenomena attend the absorption of the higher olefins in hydrobromic acid. Hydrochloric acid, on the other hand, does not show such marked activity toward the higher olefins ind is practically devoid of activity toward ethylene. 

ETHYL HYDRATE (64-17-5) Forms explosive mixture with air [flash point 55°F/13°C 68°F/20°C (80%) 72°F/22°C (60%) 79°F/26 C (40%)]. Reacts, possibly violently, with strong oxidizers, bases, acetic anhydride, acetyl bromide, acetyl chloride, aliphatic amines, bromine pentafluoride, calcium oxide, cesium oxide, chloryl perchlorate, disulfuryl difluoride, ethylene glycol methyl ether, iodine heptafluoride, isocyanates, nitrosyl perchlorate, perchlorates, platinum, potassium-terr-butoxide, potassium, potassium oxide, potassium peroxide, phosphorus(III) oxide, silver nitrate, silver oxide, sulfuric acid, oleum, sodium, sodium hydrazide, sodium peroxide, sulfinyl cyanamide, tetrachlorosilane, i-triazine-2,4,6-triol, triethoxydialuminum tribromide, triethylaluminum, uranium fluoride, xenon tetrafluoride. Mixture with mercury nitrate(ll) forms explosive mercury fulminate. Forms explosive complexes with perchlorates, magnesium perchlorate (forms ethyl perchlorate), silver perchlorate. Flow or agitation of substance may generate electrostatic charges due to low conductivity. 

Sulfuric acid is particularly useful because it forms, with many types of organic substances, intermediate compounds that themselves readily undergo hydrolysis. This is exhibited in the add process of fat splitting to make fatty adds, in making alcohol from ethylene, and probably also in the hydration of acetylene to make aldehyde. In all these, sulfuric add exhibits a specific action, distinct from its hydrogen-ion conc tiation, and cannot be replaced by other acids. 

In the indirect ethylene hydratization process ethylene is contacted at 10-15 bar and 65-85 °C with concentrated sulfuric acid in a bubble column reactor. Mono and diethyl sulfate form and are hydrolyzed later (70-100 °C) to ethanol. Diethyl ether is the main side-product of the process (up to 10%). In the downstream of the reactor, ethanol and diethyl ether are distilled from the diluted sulfuric add, neutralized, and separated by rectification. The diluted sulfuric add produced in the process (45-60% sulfuric add after water addition) is reenergy intensive and problematic with resped to corrosion issues. Despite its relatively complex process scheme, the total ethanol yield in the indired ethylene hydratization process is only 86%. One advantage of the indired process, however, is that it also works with diluted ethylene feeds (e.g., feeds containing larger amounts of methane and ethane). 

Direct hydration of propylene in a vapor-phase, catalytic process also is commercially practiced. This is similar to hydration of ethylene to make ethanol. Relative to the sulfuric acid-mediated process, it offers the advantage of decreased corrosion. However, it suffers from a requirement for a pure propylene feed, whereas the former process can be used with a dilute, refinery stream. 

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