DYNAMICS OF AN EXCITED ACID IN 1-PROPANOL-WATER MIXTURES

The excited state proton transfer reaction of 4-hydroxy-1-naphthalenes ulphonate in 1-propanol-water mixtures has been studied at six differe nt temperatures ranging from 5 to 60 degrees C. Because of the hydroph obic interaction in these mixtures, the dissociation of the probe cann ot be explained by a simple water dimer model which we found to be app licable to methanol-water and ethanol-water mixtures. In 1-propanol-wa ter mixtures the proton acceptor concentration, however, shows a linea r dependence on the water concentration above a certain critical conce ntration of water. This behavior is explained by a new model assuming a water dimer within a water cluster to be the effective proton accept or.