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Vol. 57 sium oleate at 18,11 except that in previous diagrams boundaries should be raised by a few per cent, to allow for interionic attraction and 100% dissociation of hydrochloric acid. The middle line of the diagram is given from e. m. f. and conductivity data of Figs. 1, 2 and 3. Most of the transition between simple crystalloidal and colloidal electrolytes takes place between 0.05 and 0.15 N for undecyl and lauryl sulfonic acids and in still more dilute solution in myristyl sulfonic acid. Above 0.1 or 0.2 N there can be but little else than colloid and hydrogen ions. The concentration of ionic micelles will be equal to that of the hydrogen ion, the remaining sulfonic acid forming neutral micelles. Summary Hydrogen-ion concentration deduced from con- (11)

The conformational and dynamic properties of 1,5-dioxa-6,7-benzocycloheptene (2; 1,5-benzodioxepin) and its dimethyl derivative (7) have been investigated by dynamic 1H and 13C nmr methods. Analysis of the spectra at low temperatures (below coalescence) indicates that the most stable seven-membered ring conformations detected for solutions in CHF2Cl are a mixture of the chair (C, 80%) and the twist-boat (TB, 20%) for 2 and a mixture of TB (64%) and C (36%) for 7. Free energy barriers were determined for the chair inversion of 2 (6.5 kcal/mol) and 7 (7.5 kcal/mol) as well as for the twist-boat pseudorotation of 7 (6.8 kcal/mol). The conformational properties of these seven-membered heterocycles are discussed and compared to those known for 2,4-benzodioxepins.