The reaction of acetonitrile with hydrogen peroxide in alkaline medium: a DFT mechanistic study of green production of amides

• Published in: Physical chemistry chemical physics : PCCP 2023-08, Vol.25 (34), p.22775-22781
• Main Authors: Casella, Girolamo, Carlotto, Silvia, Ribeiro, Ana P.C, Martins, Luísa M.D.R.S
• Format: Article
• Language: English
• Subjects: Acetonitrile; Amides; Configurations; Decomposition reactions; Hydrogen peroxide; Hydrolysis; Reaction mechanisms
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/d3cp02024j

We have investigated using DFT methods the reaction mechanism of the Radzisewski reaction to obtain an amide via the reaction of ACN and H 2 O 2 under alkaline conditions. The direct reaction between ACN and H 2 O 2 showed a quite high activation energy (about 45 kcal mol −1 ) rendering this path unreliable. Instead, a fast reaction between ACN and HOO − forming the deprotonated species ( PAIA − ) of the peroxyacetimidic acid ( PAIA ) was observed. From this, PAIA − was guessed to form PAIA through a fast reaction of hydrolysis. Moreover, a second way of formation of PAIA , through an OH − catalyzed path, made the rate determining step (RDS) in very good agreement with experimental data, hence neglecting the contribution of the kinetically favored hydrolysis of PAIA − . This discrepancy was reconciled by considering that the final amide was obtained through a regioselective path forming the PAIA and the further reaction involving the decomposition of PAIA and PAIA − . Indeed, the PAIA obtained from the hydrolysis reaction showed a configuration which did not match the configurational behavior required. Conversely, the PAIA formed from the RDS path matched the required configuration needed to obtain the amide. Our findings also disentangled the experimenal debate on the assignment of the RDS. The formation of acetamide from ACN + H 2 O 2 in alkaline medium has been investigated at the DFT level. The role of pH and temperature, and the determination of the rate determining step were discussed on the basis of early experimental data.