Solubility of tris(hydroxymethyl)aminomethane in water-methanol solvent mixtures and medium effects in the dissociation of the protonated base

Abstract

T he di ssoc ia tion co nsta nt of th e p rotonated fo rm of tri s(hyd roxy me th yl)a min o me th a ne has bee n meas ured at 25 °C in wa te r· me th a no l so lve nt s co nta inin g 30, SO , 70 , a nd 90 wt pe rce nt me thanol by mea ns of pote ntiomet ric titrations. The so lu bilit y of tri s(hydroxy met hy1)a min ometh a ne at 15. 25. a nd 35 °C in wa te r· me th a nol so lve nts co nt ain ing from 0 to 100 pe rce nt metha nol has bee n determin ed. Th e res ults are d isc ussed in te rm s of fr ee e ne rgies of tra nsfer a nd " medium effec ts" for hydrochl oric ac id, tri s(hyd roxy me th yl)a min ometh a ne, a nd tri s(hydroxyme th yl)amino met hane h ydrochlorid e. Key W ord s: Di ssoc ia tion co nsta nt , medium effect, meth a no l·wate r solv e nts, so lu bilit y, tri s(hydroxy me th yl)a min ometha ne.