Naslov
Direct Metal-Free Transformation of Alkynes to Nitriles: Computational Evidence for the Precise Reaction Mechanism

Autori
Hok, Lucija ; Vianello, Robert

Izvornik
International journal of molecular sciences (1422-0067) 22 (2021), 6; 3193, 16

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
azides ; DFT calculations ; cyanides ; N-iodosuccinimide ; triple C≡C bond cleavage

Sažetak
Density functional theory calculations elucidated the precise reaction mechanism for the conversion of diphenylacetylenes into benzonitriles involving the cleavage of the triple C≡C bond, with N-iodosuccinimide (NIS) as an oxidant and trimethylsilyl azide (TMSN3) as a nitrogen donor. The reaction requires six steps with the activation barrier ΔG‡ = 33.5 kcal mol−1 and a highly exergonic reaction free-energy ΔGR = −191.9 kcal mol−1 in MeCN. Reaction profiles agree with several experimental observations, offering evidence for the formation of molecular I2, interpreting the necessity to increase the temperature to finalize the reaction, and revealing thermodynamic aspects allowing higher yields for alkynes with para-electron-donating groups. In addition, the proposed mechanism indicates usefulness of this concept for both internal and terminal alkynes, eliminates the option to replace NIS by its Cl- or Br-analogues, and strongly promotes NaN3 as an alternative to TMSN3. Lastly, our results advise increasing the solvent polarity as another route to advance this metal-free strategy towards more efficient processes.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

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