Surface active properties of simple cyclic and heterocyclic amines in water.

The surface tension of aqueous solutions of simple cyclic, heterocyclic and aromatic amines was measured with a Du Nöuy tensiometer at 25 degrees C and the results discussed in terms of structure-aggregation relationships. The simple compounds used in this study were piperazine, piperidine, morpholine, 3-methylpyridine, cyclohexylamine and benzylamine, with carbon numbers ranging from four to seven. Piperazine, piperidine and morpholine did not form micellar associations but cyclohexylamine, benzylamine and 3-methylpyridine did, indicating that more than six carbons are necessary to form micellar associations, at least for compounds having a six-membered ring.