Computational study of mechanistic pathway and effect of zero valent metals on reductive debromination of some polybrominated biphenyls

Lukman O. Olasunkanmi, Olaide O. Wahab, Adebukola H. Oladokun, Adedolapo O. Adepoju, Penny P. Govender

Research output: Contribution to journalArticlepeer-review

Abstract

Complete debromination of three polybrominated biphenyls (PBBs), namely 2,2′,3,3′,4,4′-hexabromobiphenyl (PBB-128), 2,2′,3,3′,4,5- hexabromobiphenyl (PBB-129) and 2,2′,3,3′,4,5′- hexabromobiphenyl (PBB-130) aided by zero valent magnesium (Mg0) and zinc (Zn0) in the presence of methanol was studied computationally using dispersion corrected ωB97XD functional with cc-pVTZ basis set. All possible debromination pathways were explored for each parent PBB and the most energetically favoured pathway was identified. Mono-debromination of each PBB afforded a two-step mechanism, viz, formation of a highly charged covalent intermediate that involves a phenyl-metal-bromine connectivity and protonation by methanol molecule. Total activation energy for the step-wise removal of one bromine substituent increased along the debromination pathway. Using substituent positions, favourable sequence of stepwise debromination was found to follow the order 3 or 3′ 2 or 2′ 4 or 4′, while Mg0 catalyzed the debromination reaction better than Zn0. The order of ease of debromination was found to be PBB-128PBB-130 PBB-129.

Original languageEnglish
Article number114238
JournalComputational and Theoretical Chemistry
Volume1227
DOIs
Publication statusPublished - Sept 2023

Keywords

  • Activation energy
  • DFT
  • Debromination pathway
  • Polybrominated biphenyls
  • Potential energy surface
  • Zero valent Metals

ASJC Scopus subject areas

  • Biochemistry
  • Condensed Matter Physics
  • Physical and Theoretical Chemistry

Fingerprint

Dive into the research topics of 'Computational study of mechanistic pathway and effect of zero valent metals on reductive debromination of some polybrominated biphenyls'. Together they form a unique fingerprint.

Cite this