The sulphation reaction between aqueous sulphuric acid and α‐olefins

The initially heterogeneous reactions between 75 to 85% w/w aqueous H2SO4 and hexene‐1, heptene‐1, octene‐1, and decene‐1, have been investigated as a necessary preliminary to the estimation of the heat associated with the production of the monoalkyl sulphates. The effects of different proportions of acid and olefin, the aqueous concentration of the acid, the temperature and the speed of stirring, were examined. At room temperatures, the reaction products isolated with a high ratio of 80% w/w acid to olefin, were substantially the secondary monoalkyl sulphates and their corresponding alcohols. Under these conditions the formation of the dialkyl sulphates and polymers was avoided. It was found possible to represent approximately the results in terms of a two‐stage consecutive reaction. RCH : CH2 → RCH(O·SO3H)‐CH3 → RCH(OH2+)·CH3 The reactions were shown in each case to be of the second order depending upon some function of the concentration of the aqueous H2SO4. The observed kinetics were shown to be in agreement with the formation of a carbonium‐ion intermediate.