Alkyl hydrogen sulphate

Cold concentrated sulphuric acid will remove unsaturated hydrocarbons present in saturated hydrocarbons, or alcohols and ethers present in alkyl halides. In the former case soluble sulphonated products are formed, whilst in the latter case alkyl hydrogen sulphates or addition complexes, that are soluble in the concentrated acid, are produced. 

Unsaturated hydrocarbons dissolve through the formation of soluble alkyl hydrogen sulphate ... 

Addition of concentrated H2SO4 to alkenes yields acid-soluble alkyl hydrogen sulphates. The addition follows Markovnikov s rule. The sulphate is hydrolysed to obtain the alcohol. The net result is Markovnikov addition of acid-catalysed hydration to an alkene. The reaction mechanism of H2SO4 addition is similar to that of acid-catalysed hydration. 

Reaction XLVIH. (b) Action of Alkali Cyanides on Alkyl Hydrogen Sulphates. (A., 10, 249.)—The alkyl nitriles may also be prepared by dry distilling alkali cyanides with alkali-alkyl-sulphates. 

Reaction LXXVII. Action of Sulphuric Add on an Alcohol or a Mixture of Alcohols. (J. Pharm., 1, 97 Phil. Mag., [3], 37, 350.)—This is the commercial method of obtaining diethyl ether from ethyl alcohol. The reaction occurs in two stages an alkyl hydrogen sulphate is first formed Rnd this yields ether on interaction with more alcohol. 

In the case of sulphur trioxide-alcohol systems the conductivity-composition curve reveals a maximum at 1 4-5 sulphur trioxide/alcohol molar ratio showing that the adducts formed are highly solvated. There is no break in the curve at a molar ratio 1 3, There are, however, breaks at 1 2 and 1 1 sulphur trioxide/alcohol molar ratios. The potentiometric, conductomeuic and visual titrations show that sulphur trioxide solutions in these alcohols behave as monobasic acids against nitrogen bases and indicate that the stable species in alcohol solutions are the tetracoordinated alkyl hydrogen sulphates which are monobasic ionizable acids. 

Ammonium hydroxide is used for the neutralisation of alkyl hydrogen sulphates (R-O-SO3H) and alkyl ether sulphates (R-(OCH2CH2) OS03H). 

The mechanism for alcohol sulphation is thought to be similar to that for LAB sulphonation, involving the rapid formation of a metastable pyrosulphate species which decomposes less fast but still rapidly to alkyl hydrogen sulphate ("acid sulphate") ... 

An important feature of sulphation chemistry is the thermal instability of the "acid sulphate", which breaks down to a mixture of products including the parent alcohol, the dialkyl sulphate (ROSO2OR), the dialkyl ether (ROR), isomeric alcohols, olefins (R CH=CH2> and esters (ROSO3R). Because of the thermal instability of the "acid sulphate" it is necessary to avoid high sulphation temperatures and to neutralise the acid sulphation product soon after its formation. An ageing time of about 1 minute at 30-50°C is adequate for the second reaction where the desired alkyl hydrogen sulphate is formed. In practice the minimum sulphation temperature feasible is determined by the need for the feedstock and reaction mixture to be mobile liquids. 

Alkyl hydrogen sulphate (RQSQ.H) and alkyl ether hydrogen sulphate R(Q.CH2CH2) aSQ3H neutralisation... 

The metallic derivatives of organic compounds that are most likely to be encountered in the course of practice analyses are salts of carboxylic acids, sulphonic acids, phenols and enols, alkyl hydrogen sulphates metallic derivatives of amides, imides and sidpho-namides sodium bisulphite adducts of carbonyl compounds. 

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