Theoretical study on the OH-initiated atmospheric reaction of N-methyl perfluorobutane sulfonamidoethanol (C4F9SO2N(CH3)CH2CH2OH)

N-methyl perfluorobutane sulfonamidoethanol (NMeFBSE), a new product of the 3M Company, is currently widely used in many countries and territories. It is prone to volatilize to the atmosphere where it can undergo long-range transport and chemical transformations. In this work, the reaction mechanism for the OH-initiated atmospheric oxidation of NMeFBSE was investigated. The geometrical parameters and vibrational frequencies of all of the stationary points were calculated at the MPWB1K level with the 6-31G+(d,p) basis set. Single-point energy calculations were carried out at the MPWB1K/6-311+G(3df,2p) level. The results indicate that the channel of the formation of C4F9 and HSO3N(CH3)CH2CH2OH resulting from OH addition to NMeFBSE and hydrogen abstractions from the -CH3 group in NMeFBSE are energetically favorable. The main degradation products include perfluorinated carboxylic acids (C3F7COOH, C2F5COOH, CF3COOH), HSO3N(CH3)CH2CH2OH, NMeFBSA (C4F9SO2NH(CH3)), C4F9SO2N(CH3)CH2CHO, and C4F9SO2N(CH3)CH2COOH. The reaction mechanism for the formation of NMeFBSA is reported for the first time. Using the atmospheric fate of NMeFBSE as a guide, it seems that N-methyl perfluorooctane sulfonamidoethanol (NMeFOSE) contributes to the ubiquity of perfluoroalkyl sulfonate and carboxylate compounds in the atmosphere.