The role of bromoalkanes on the catalytic activation of carbon-supported gold nanoparticles for hydration of terminal alkynes

• Metal vapor synthesis derived Au/C active for hydration of alkynes with the presence of bromoalkane. • Hot filtration and leaching test indicate heterogenous pathway of the catalyst. • AuNP-bromoalkane system is catalytically active for various terminal alkynes. We here report that traces of long-chain bromoalkanes can activate carbon-supported Au(0) nanoparticles (NPs) for terminal alkyne hydration to methylketones. This AuNP-bromoalkane system is effective for both aliphatic and aromatic substrates, yielding high Markovnikov product selectivity (up to 93%). Hot filtration tests and the absence of leached Au suggest surface-bound Au NPs drive the catalytic activity. The catalyst is easily recoverable and reusable for several recycle runs. Overall, the findings presented in this contribution reveal the non-innocent role of bromine-containing impurities, underscoring the importance of their careful consideration when evaluating the activity of Au-based catalytic systems.