In an earlier paper'it was shown that propiolactone reacted with sulfanilic acid to yield N-(2- carboxyethy1)-sulfanilic acid (I). It was considered possible that the lactone reacted first at the sulfonate ion to form a sulfonic ester 11, which then alkylated the amino group. This now appears improbable, and direct reaction at the amino position is suggested instead. As evidence against the first formulation there is
