New Insight into the Chloroacetanilide Herbicide Degradation Mechanism through a Nucleophilic Attack of Hydrogen Sulfide.

ABSTRACT: The nucleophilic attack of hydrogen sulfide (HS-) on six different chloroacetanilide herbicides was evaluated theoretically using the dispersion-corrected hybrid functional wB97XD and the 6-311++G(2d,2p) Pople basis sets. The six evaluated substrates were propachlor (A), alachlor (B), metolachlor (C), tioacetanilide (D), β-anilide (E), and methylene (F). Three possible mechanisms were considered: (a) bimolecular nucleophilic substitution (SN²) reaction mechanism, (b) oxygen assistance, and (c) nitrogen assistance. Mechanisms based on O- and N-assistance were discarded due to a very high activation barrier in comparison with the corresponding SN² mechanism, with the exception of compound F. The N-assistance mechanism for compound F had a free activation energy of 23.52 kcal/mol, which was c

SUBMITTER: Mora JR 

PROVIDER: S-EPMC6213056 | biostudies-literature | 2018 Sep

REPOSITORIES: biostudies-literature