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Article

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

Division of Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Bijenička Cesta 54, 10000 Zagreb, Croatia
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Author to whom correspondence should be addressed.
Academic Editor: Oleg V. Mikhailov
Int. J. Mol. Sci. 2021, 22(6), 3193; https://doi.org/10.3390/ijms22063193
Received: 29 January 2021 / Revised: 10 March 2021 / Accepted: 19 March 2021 / Published: 21 March 2021
(This article belongs to the Special Issue From Molecules to Colloids: Recent Advances in Their Chemical Physics)
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. View Full-Text
Keywords: azides; DFT calculations; cyanides; N-iodosuccinimide; triple C≡C bond cleavage azides; DFT calculations; cyanides; N-iodosuccinimide; triple C≡C bond cleavage
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MDPI and ACS Style

Hok, L.; Vianello, R. Direct Metal-Free Transformation of Alkynes to Nitriles: Computational Evidence for the Precise Reaction Mechanism. Int. J. Mol. Sci. 2021, 22, 3193. https://doi.org/10.3390/ijms22063193

AMA Style

Hok L, Vianello R. Direct Metal-Free Transformation of Alkynes to Nitriles: Computational Evidence for the Precise Reaction Mechanism. International Journal of Molecular Sciences. 2021; 22(6):3193. https://doi.org/10.3390/ijms22063193

Chicago/Turabian Style

Hok, Lucija, and Robert Vianello. 2021. "Direct Metal-Free Transformation of Alkynes to Nitriles: Computational Evidence for the Precise Reaction Mechanism" International Journal of Molecular Sciences 22, no. 6: 3193. https://doi.org/10.3390/ijms22063193

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