Electrocatalytic synthesis of α,α--dihalide ketones from α-mono-halide ketones and unexpected dimer condensation
A novel, environmentally friendly electrocatalytic process has been developed to prepare α,α- gem -dihalide (F, Cl, and Br) ketones from α-mono-halide ketones in an aqueous solution containing alkali halide salts. The gem -dihalides could have the same or different halogens on the same carbon, depen...
Saved in:
Published in | Green chemistry : an international journal and green chemistry resource : GC Vol. 24; no. 7; pp. 2859 - 287 |
---|---|
Main Authors | , , , , , , , , , |
Format | Journal Article |
Published |
04.04.2022
|
Online Access | Get full text |
Cover
Loading…
Summary: | A novel, environmentally friendly electrocatalytic process has been developed to prepare α,α-
gem
-dihalide (F, Cl, and Br) ketones from α-mono-halide ketones in an aqueous solution containing alkali halide salts. The
gem
-dihalides could have the same or different halogens on the same carbon, depending on the reactant and inorganic halide salt used. An electron-withdrawing group, such as carbonyl, located at the α-site of mono-halogenated carbon, was essential to the reaction. The electrosyntheses were performed under ambient conditions without inert gas protection and displayed yields of about 80%. This method avoided the classical haloform elimination reaction. However, when the aqueous solution contained NaOH, two α-mono-halide ketone molecules had a special dimer condensation. The reaction mechanisms were explored by conducting GC-MS, EPR, and CV with DFT calculations. These revealed that
in situ
generation of a halogen radical initiated electrocatalytic halogenation, while the dimer condensation involved a hydroxyl radical-mediated C1 fragment elimination.
Starting from α-mono-halide ketone, this paper demonstrates a novel electrocatalytic method of halogenation for α,α-
gem
-dihalide ketone synthesis and a NaOH-mediated dimer condensation reaction for keto-ester synthesis. |
---|---|
Bibliography: | Electronic supplementary information (ESI) available. CCDC For ESI and crystallographic data in CIF or other electronic format see DOI 10.1039/d1gc04584a 2106444 |
ISSN: | 1463-9262 1463-9270 |
DOI: | 10.1039/d1gc04584a |