Ethyl hydrogen sulphate

When concentrated sulphuric acid is added to ethanol, the mixture becomes hot owing to the formation of ethyl hydrogen sulphate, the yield of which is increased if the mixture is then gently boiled under reflux ... 

If the mixture contains an excess of ethanol, and is heated to 140°, the ethyl hydrogen sulphate reacts with the ethanol, giving diethyl ether And regenerating the sulphuric acid ... 

If the mixture contains a considerable excess of sulphuric acid and is heated to 160-170 , the ethyl hydrogen sulphate breaks down, giving ethylene and again regenerating the sulphuric acid. 

This ion (1) can react in three ways, according to the conditions. (a) reaction with the HSOj may give ethyl hydrogen sulphate... 

Pure ethyl hydrogen sulphate is difficult to prepare, as it is an oily liquid, very soluble in water, and easily hydrolysed. It is therefore usually isolated as the potassium salt, since potassium ethyl sulphate crystallises well from water, and is not readily hydrolysed in neutral or weakly alkaline solution. 

CH3COOH + HOC2H5 - CH3GOOC2H3 + H2O If, however, concentrated sulphuric acid is present, the water is absorbed, the back reaction prevented, and a high yield of ethyl acetate is obtained. In practice the reaction is not so simple. It was formerly supposed that, since the sulphuric acid is usually added to the alcohol, ethyl hydrogen sulphate and water are formed, the latter being absorbed by the excess of sulphuric acid, A mixture of ethanol and acetic acid is then added to the ethyl hydrogen sulphate,... 

Diethyl ether may be prepared from ethyl alcohol by the sulphuric acid process. A mixture of alcohol and sulphuric acid in equimolecular proportions is heated to about 140° and alcohol is run in at the rate at which the ether produced distils from the reaction mixture. Ethyl hydrogen sulphate (or ethyl sulphuric acid) is first formed and this yields ether either by reacting directly with a molecule of alcohol or by the formation and alcoholysis of diethyl sulphate (I) ... 

If the temperature is allowed to rise to 170°, much of the ethyl hydrogen sulphate decomposes into ethylene ... 

The sulphuric acid and ethyl hydrogen sulphate required in reactions 1 and 3 respectively are regenerated in reactions 2 and 4, but the water formed is retted in the acid mixture and ultimately results in such a dilution that the caiversion into ether is no longer efficient. Furthermore, some ethylene is always formed this partly polymerises to give materials capable of reacting with sulphuric acid and reducing it to sulphur dioxide. In industrial practice, sulphuric acid is sufficient for the production of about 200 parts of ether. 

Boil a little of the solution of the salt with a few drops of dilute hydrochloric acid for a minute and add barium chloride. A precipitate of barium sulphate is formed, as, on boiling ethyl hydrogen sulphate in aqueous solution, it is decomposed into sulphuric acid and alcohol (see Appendix, p. 234). 

The simple acidic nature of chlorosulphonic acid is also manifested in the existence of corresponding ethereal salts, the ethyl ester C1.S02. OCaII8 being obtainable indirectly by the action of phosphorus penta-chloride on ethyl hydrogen sulphate (ethylsulphuric acid), C2H50. S03.0H, or by the interaction of sulphuryl chloride and ethyl alcohol 1... 

On the other hand, Elliott and his co-workers 4 maintain that the evidence for the nitro- structure is unsatisfactory, and that the p-nitro-dimethylaniline produced with dimethylaniline is a secondary product obtained either by oxidation of the nitroso-compound or by direct nitration of the amine. The addition of ethyl hydrogen sulphate to a solution of nitrosulphonic acid in sulphuric acid does not yield nitro -ethane. Elliott suggests that the crystalline acid is essentially the nitroso- form, ON. O. SO 2. OH, but that in the molten condition and in sulphuric acid solution this form is in equilibrium with another of yO ... 

They are commonly prepared by the esterification of ethyl alcohol by the corresponding acids monochloracetic, bromoacetic, etc., using sulphuric acid as dehydrating agent. This acid first reacts with alcohol to form ethyl hydrogen sulphate ... 

Ethyl hydrogen sulphate Ethyl acid sulphate... 

NOTE.—The sulphuric acid used in the preparation serves as a catalytic agent. The amount of alcohol used is that equivalent to the acid (equal molecular proportions) plus that which combines with the sulphuric acid to form ethyl hydrogen sulphate. The ester obtained in the first distillation contains alcohol and acetic acid. The former is removed by shaking with calcium chloride, and the latter by treatment with sodium carbonate. 

Ethylene is recovered by heating the solution of ethyl hydrogen sulphate in concentrated sulphuric acid to 160°-170°C. 

Ethyl Hydrogen Sulphate, C2H5.HSO4, is an oily liquid, resembling sulphuric acid, which can not be distilled without decomposition. It is usually called ethyl sulphuric acid as it... 

---