Mechanism of Base-Catalyzed Halogen Dance Reactions and the Role of Bromo-Bridged Transition States

Submitting author affiliation:
University of Illinois, Urbana, United States

Beilstein Arch. 2020, 202086.

Published 27 Jul 2020

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This preprint has not been peer-reviewed. When a peer-reviewed version is available, this information will be updated.


Base-catalyzed halogen dance reaction, has puzzled chemists ever since, to come up with new ideas regarding the mechanism of this beautiful chemical transformation. Series of fast metal-halogen exchanges are among the most recent mechanisms. Using DFT-Cam-B3LYP/ land2dz computations and focused on Halogen Dance (HD) reactions of bromobenzene derivatives, new bromo-bridged Transition States (TS) are proposed. These are then used to lay out 8 possible isomerization and 18 possible disproportionation paths. Mechanistic pathways were then analyzed based on TS’s energy and protonation/deprotonation steps to find the most suitable pathways. Overall pattern of these mechanisms draws for the first-time a cascade-like pattern for base-catalyzed halogen dance in its entirety. The present work shed light on a dynamic domino mechanism which dominates the realm of nonaqueous strongly basic medium reactions. Trends like these may well be a shared feature in base digestion of wood for its precious poly aromatic component like lignin.

Keywords: mechanistic pathways, dynamic domino mechanisms, base-catalyzed halogen dance, nonaqueous strongly basic medium, bromo-bridged Transition State, disproportionation paths.

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When a peer-reviewed version of this preprint is available, this information will be updated in the information box above. If no peer-reviewed version is available, please cite this preprint using the following information:

Sakhaee, N.; Fazaeli, Y.; Doustkhah, E.; Sakhaee, S.; Takallou, A.; Mobaraki, A. Beilstein Arch. 2020, 202086. doi:10.3762/bxiv.2020.86.v1

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