Ab initio investigation of the O-H insertion reactions of CH2X-X (X = Cl, Br, I) isopolyhalomethanes with water

Here, we report ab initio calculations for the O-H insertion reactions of CH2X-X (X = Cl, Br, I) with H2O and examine substituent effects for changing the halogen atom. As Cl changes to Br and then I, the O-H insertion reactions lead to an HX acid leaving group and range from about 2.3 kcal/mol for X = Cl to about 16.3 kcal/mol for X = I. We compare the trends as the halogen atom varies from Cl to Br and I in the O-H insertion reactions of CH2X-X with H2O to the cyclopropanation reactions of CH2X-X with ethylene. We very briefly discuss possible implications for phase-dependent photochemistry of polyhalomethanes in the atmosphere.