Search

• DFT calculations decipher the complete mechanism of the H-P-E-S-W reaction in DMSO. • The dehydration step of the ketol intermediate proceeds via an E 1 cB mechanism. • In the rate-determining step of ketol intermediate formation a water molecule catalyses the transformation, by acting as a proton shuttle. The use of (S)-proline as a catalyst for intramolecular aldol reactions pioneered by Hajos, Parrish, Eder, Sauer and Wiechert paved the way for modern organocatalysis, which earned MacMillan and List the Nobel Prize in Chemistry in 2021. The work reported herein shed light on mechanistic aspects regarding the "prototypal" H-P-E-S-W reaction that, up to date, are unclear. The DFT calculations determined i) the mechanism of the dehydration step of the ketol intermediate that proceeds via an E 1 cB (elimination, unimolecular, conjugate base) mechanism; ii) the rate-determining steps (RDS) of the H-P-E-S-W reaction that correspond to enamine formation and dehydration; iii) the catalytic role of the water molecule formed during the reaction, that behaves as a proton shuttle during the enamine and C C bond formation and determines a significant lowering of the activation barriers. [Display omitted] [ABSTRACT FROM AUTHOR]

The exponentially growing market of electrochemical energy storage devices requires substitution of flammable, volatile, and toxic electrolytes. The use of Water in salt solutions (WiSE) regarded as green electrolyte might be of interest thanks to an association of key features such as high safety, low cost, wide electrochemical stability, and high ionic conductivity. Here, we report comprehensive chemical-physical study of circumneutral WiSE based on ammonium acetate so as to investigate application in electrochemical energy storage systems, with focus on the effect of pH, density, viscosity, conductivity, and the ESW with salt concentration ranging from 1 to 30 mol kg−1. Data are reported and discussed with respect to the structure of the solutions investigated by complemental IR and molecular dynamic study. The study is addressed through the showcase of an asymmetric supercapacitor based on Argan shell-derived carbon electrodes tested at temperatures ranging from -10 to 80 °C. [ABSTRACT FROM AUTHOR]