Influence of the Chemical Environment on Metolachlor Conformations

Metolachlor exists in multiple, different stable conformations in solution. Assignment of the NMR frequencies to chemical structure is a prerequisite to understanding the behavior of individual conformations. 1H NMR experiments of metolachlor in different chemical environments identified the labile sites of metolachlor and environments that influence conformational/configurational changes. Within very specific chemical environments, metolachlor atropisomers aS,12S (aR,12R) and aR,12S (aS,12R) freely interchange, and consequently, the multiple conformations also interchange. The changes in chemical environments, which most alter the conformations and molecular dynamics of metolachlor, identify the most critical components affecting its environmental fate. These results enable a structural interpretation of conformational changes that can influence the environmental fate of metolachlor. Keywords: Metolachlor; NMR; molecular mechanics; chemical environment; atropisomers