SMALL HYDROPHOBIC ORGANIC IONS IN AQUEOUS-SOLUTIONS

Small-angle neutron scattering experiments were performed at 25-degrees-C on solutions of tetraphenylphosphonium chloride and sodium tetraphenylborate in deuterated water and in deuterated dimethylformamide. The results show a strong attraction between either the organic cations or the organic anions when the salts are dissolved in water. On the contrary, in the organic solvent the attraction between the equally charged organic ions is found to be very weak. This is the first structural evidence of hydrophobic association of small organic ions in water.