2026-04-17T15:50:33Zhttps://recercat.cat/oai/request

oai:recercat.cat:2445/1954462025-12-04T21:44:13Zcom_2072_1057col_2072_478917col_2072_478933

00925njm 22002777a 4500 dc Costa i Arnau, Anna M. author Castro Álvarez, Alejandro author Fillot, Daniel author Vilarrasa i Llorens, Jaume author 2023-03-17T10:27:19Z 2023-08-08T05:10:27Z 2022-08-08 2023-03-17T10:27:19Z The energies of CH2=CH−CH=N+R2+HNR*2→CH2=CH−CH=N+R*2+HNR2 reactions (exchange of propenal between two secondary amines) and of similar equilibria with cinnamaldehyde have been calculated and compared. Iminium ions from pyrrolidines with substituents that can help stabilize the positive charge are especially stable in the gas phase, as expected, whereas in very polar solvents the predicted order of stability (of their iminium ions) is: O-tert-butyldiphenylsilylprolinol>pyrrolidine>O-methylprolinol>2-tert-butylpyrrolidine>Jørgensen-Hayashi catalyst>2-tritylpyrrolidine>N,N-dimethylprolinamide>trimethylsilyl prolinate>3-triflamidopyrrolidine>methyl prolinate≫MacMillan-1 catalyst>MacMillan-2 catalyst. When ion pairs such as iminium tetrafluoroborates, in CHCl3, are compared, the order is similar. These data can be used to predict which iminium salts may predominate when two or more secondary amines and appropriate acids are added to conjugated carbonyl compounds. Química física Ions Physical and theoretical chemistry Ions Computational Comparison of the Stability of Iminium Ions and Salts from Enals and Pyrrolidine Derivatives (Aminocatalysts)