1-01, s:
Rb > K. The order of reactivity with water is C1> Br > I.
medium effects for salts or strong acids even up to rather high ionic concentration^.^-^ Thus, if we ascribe the medium effect on R entirely to proton transfer, the ratio CC,H~SO~-/CC,H,SO~His unity a t about 43 wt. % H2S04. Using this datum, we Los ALAMOSSCIENTIFIC LABORATORY LOSALAMOS,~ V E WMEXICO L. B. ASPREY could estimate pK, of p-toluenesulfonic acid if DEPARTMENT OF CHEMISTRY JOHNL. MARGRAVEthe appropriate acidity function, H-, were known.Y UNIVERSITYOF WISCONSIX MERLIS E , Unfortunately, this function is not known for aryll f ADISON, T.T.'ISCONSIN sulfonic acids in 13 wt. yo H2S04. We may, howRECEIVED JUSE 2, 1961 ever, approximate its value by using recent data for the ionization of nitric as shown in MOLAR REFRACTION AS AN INDEX OF PROTON equation (1). On this basis, ~ K for A p-tOlUeneSLllTRANSFER : AN ESTIMATE OF T H E ACID STRENGTH PKA(CiHiS03H) = PR.
