Sulfonation with sulfur trioxide

T H E purpose of this pape r is to present some of the more impor tan t factors encountered in the S Q sulfonation of a lkylaryl hydrocarbons. This should serve as a basis for discussion and fu r the r s tudy by those interested in the expanding field of a lkylaryl snlfonate detergents. The established method of producing this type of synthetic detergent has been to sulfonate with sulfuric acid. The s t rength of acid used may be f rom 98% to 20% free SOu oleum. Quant i ty of acid ranges f rom 1 to 1.5 pounds of acid per pound of a lkylaryl hydrocarbon. The excess spent sulfuric acid is separa ted by a drowning procedure. The use of SO3 as a sulfonating agent for the prepara t ion of synthetic detergents is a relat ively new art. I t is practiced by only a few companies, but it is of rap id ly increasing interest. This paper will be limited to a lkylaryl snlfonates of the type t~SQM, where R is a 12-carbon alkyl subst i tuted benzene and M is a metal or amine group. The alkyl group is a propylene polymerization product. The work was carr ied out in pilot scale equipment. Sufficient data were obtained to indicate the feasibil i ty of the operation on a commercial scale.