Ab initio molecular dynamics study on the hydrolysis of molecular chlorine

The hydrolysis of Cl₂ in water and its reverse reaction, modeled by a box containing one Cl₂ and 19 H₂O molecules, are studied by ab initio molecular dynamics. It is observed that the hydrolysis reaction involves only Cl₂ and one H₂O molecule directly in bond breaking and formation and that solvated chloride and hydrogen ions are directly produced in the hydrolysis. For the reverse reaction between HCl and HOCl, the approaching HOCl must first penetrate a solvation shell of water around the chloride ion, and the calculated free energy barrier is approximately 4.6 kcal mol^-1, much lower than that in the gas phase. The presence of (H₂OCl)⁺Cl^- is identified when the Cl-Cl distance is constrained at 2.2 or 2.4 Å.

© 1999 Elsevier Science B.V.