Preparation of alkylaromatic hydrocarbons and alkylaryl sulfonates

n2n 13 An alkylaromatic hydrocarbon composition prepared by the process which comprises oligomerizing an olefin selected from the group consisting of propylene, n-butene and mixtures thereof over an oligomerization catalyst, to form a oligomerization product comprising at least 95% by weight of mono-olefin oligomers of the empirical formula: CH wherein n is greater than or equal to 10, the mono-olefin oligomers comprise at least 20% by weight of olefins having at least 12 carbon atoms, and the olefins having at least 12 carbon atoms having an average of from 0.8 to 2.0 C-Calkyl branches per carbon chain. Sulfonation of the alkylaromatic hydrocarbon product produces an alkylaryl sulfonate mixture that exhibits advantageous properties, such as biodegradability and hard and cold water performance.