Henry's law constants and hydrolysis rate constants of 2,2,2-trifluoroethyl acetate and methyl trifluoroacetate

摘要

Henry's law constants (H) and hydrolysis rate constants (k_h) of two fluorinated esters [CH_3C(O)OCH_2CF_3 and CF_3C(O)OCH_3] were determined at 278-298 K by a column-stripping method. The H value at 298 K (H_(298)) and the standard solvation enthalpy for gas-to-liquid transfer (ΔH_(sol)) were determined from the van't Hoff equation to be H_(298)= 0.58+-0.04 M atm~(-1) and ΔH_(sol)= -44+-3 kJ mol~(-1) for CH_3C(O)OCH_2CF_3, and H_(298)= 0.12+-0.04 M atm~(-1) and ΔH_(sol) = -41+-16 kJ mol~(-1) for CF_3C(O)OCH_3. Hydrolysis of CH_3C(O)OCH_2CF_3 was not obser-ved(k_h<7x 10~(-5) s~(-1)), whereas the k_h value of CF_3C(O)OCH_3 was determined to be 10~(5.3+-2.0)exp{ - (5.07+-1.27) x 10~3/T} s~(-1). The effects of pH and metal ions, and the salting-out effects of NaCl were also examined for CH_3C(O)OCH_2CF_3. Dissolution in seawater is expected to be a significant tropospheric sink of these fluorinated esters.