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We have investigated using DFT methods the reaction mechanism of the Radzisewski reaction to obtain an amide via the reaction of ACN and H2O2 under alkaline conditions. The direct reaction between ACN and H2O2 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. [ABSTRACT FROM AUTHOR]

This work concerns recent advances (mainly in the last five years) in the challenging conversion of carbon dioxide (CO2) into fine chemicals, in particular to cyclic carbonates, as a meaningful measure to reduce CO2 emissions in the atmosphere and subsequent global warming effects. Thus, efficient catalysts and catalytic processes developed to convert CO2 into different chemicals towards a more sustainable chemical industry are addressed. Cyclic carbonates can be produced by different routes that directly, or indirectly, use carbon dioxide. Thus, recent findings on CO2 cycloaddition to epoxides as well as on its reaction with diols are reviewed. In addition, indirect sources of carbon dioxide, such as urea, considered a sustainable process with high atom economy, are also discussed. Reaction mechanisms for the transformations involved are also presented. [ABSTRACT FROM AUTHOR]