2- ethyl hydrogen sulfate

Diethyl sulfate can be prepared by a vahety of methods. When ethyl hydrogen sulfate is heated with sodium chloride to 80°C, hydrogen chloride is hberated. The resulting reaction mixture is then distilled at 1.33—2.00 kPa (10—15 mm Hg) at a maximum ketde temperature of 190°C to give diethyl sulfate in 90% yield (95). 

Passing a stream of nitrogen at 95—100°C through a reaction mixture of ethyl ether and 30 wt % oleum prepared at 15°C results in the entrainment of diethyl sulfate. Continuous operation provides a >50% yield (96). The most economical process for the manufacture of diethyl sulfate starts with ethylene and 96 wt % sulfuric acid heated at 60°C. The resulting mixture of 43 wt % diethyl sulfate, 45 wt % ethyl hydrogen sulfate, and 12 wt % sulfuric acid is heated with anhydrous sodium sulfate under vacuum, and diethyl sulfate is obtained in 86% yield the commercial product is >99% pure (97). 

Absorption of ethylene in concentrated sulfuric acid to form monoethyl sulfate (ethyl hydrogen sulfate) and diethyl sulfate ... 

The absorption is carried out by countercurrent passage of ethylene through 95—98% sulfuric acid in a column reactor at 80°C and 1.3—1.5 MPa (180—200 psig) (41). The absorption is exothermic, and cooling is required (42) to keep the temperatures down and thereby limit corrosion problems. The absorption rate increases when ethyl hydrogen sulfate is present in the acid (43—46). This increase is attributed to the greater solubiUty of ethylene in ethyl hydrogen sulfate than in sulfuric acid. 

Diethyl ether is the principal by-product of the reaction of ethyl alcohol with diethyl sulfate. Various methods have been proposed to diminish its formation (70—72), including separation of diethyl sulfate from the reaction product. Diethyl sulfate not only causes an increase in ether formation but is also more difficult to hydroly2e to alcohol than is ethyl hydrogen sulfate. The equiUbrium constant for the hydrolysis of ethyl hydrogen sulfate is independent of temperature, and the reaction rate is proportional to the hydrogen ion concentration (73—75). 

Heat of solulion followed by reaction to form ethyl hydrogen sulfate. 

The process involves ethanol and acetic acid reacting reversibly to ethyl acetate, using a catalyst, ethyl hydrogen sulfate, which is prepared by reaction be-... 

Propene undergoes little polymerization when treated with 96% sulfuric acid, the chief product being isopropyl hydrogen sulfate which yields isopropyl alcohol on hydrolysis. When 98% sulfuric acid is used, propylene is converted to conjunct polymer. Ethylene cannot be polymerized by sulfuric acid because the stable ethyl hydrogen sulfate and ethyl sulfate are formed attempts to obtain the polymerization by increasing the reaction temperature are unsuccessful because oxidation occurs. 

Exercise 10-8 Show the steps involved in the formation of ethyl hydrogen sulfate from ethene and sulfuric acid. Show how diethyl sulfate, (CH3CH20)2S02, could be formed from the same reagents. 

In the original process, ethylene gas was fed into strong sulfuric acid (around 90 per cent) at moderate temperatures and near atmospheric pressure. The ethylene was converted largely to ethyl hydrogen sulfate, but partly to diethyl sulfate. Some polymerization of the ethylene also took place. 

Sulfuric acid, hydrogen fluoride, and aluminum chloride are the general catalysts used commercially. Sulfuric acid is used with propene and higher-boiling feeds, but not with ethylene, because it reacts to form ethyl hydrogen sulfate. The acid is pumped through the reactor and forms an air emulsion with reactants, and the emulsion is maintained at 50 percent acid. The rate of deactivation varies with the feed and isobutane charge rate. Butene feeds cause less acid consumption than the propene feeds. 

There is some evidence (SO), although it is not very conclusive that ethyl hydrogen sulfate is itself a rather weak base ionizing slightly according to the equation... 

Sabatier 42 attributes the dehydration of alcohols over the surfaces of the oxides of thoria, alumina, and tungsten to the formation on the surface of these oxides, with the elimination of water, of a thin layer of an ester comparable to ethyl hydrogen sulfate. This ester is decomposed by heat into an olefin and the regenerated oxide. Thus ... 

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