In:
International Journal of Quantum Chemistry, Wiley, Vol. 120, No. 9 ( 2020-05-05)
Kurzfassung:
For the traditional reduction of ketones and aldehydes, NH 3 BH 3 ( AB ) and N ‐methyl amine borane ( M n AB ) have been effective reducing agents. However, the reaction process is indefinite and different mechanisms have been proposed; also the solvent effect, which is closely related to the mechanism, has not been considered seriously. Here we employ density functional theory to carry out a comprehensive study on the mechanism. The calculated free energy of the concerted double hydrogen transfer process is lower than the hydroboration mechanism by 4.7 kcal/mol, which indicates that reduction of carbonyl by AB is likely due to be the concerted double hydrogen transfer in both aprotic (tetrahydrofuran) and protic (MeOH) solvents. For the reduction by M n AB , the corresponding free energies of all reactions are higher than those of AB . Meanwhile, the reduction of benzaldehyde by M n AB ( n = 1, 2) also favors a concerted double hydrogen transfer rather than hydroboration.
Materialart:
Online-Ressource
ISSN:
0020-7608
,
1097-461X
Sprache:
Englisch
Verlag:
Wiley
Publikationsdatum:
2020
ZDB Id:
1475014-4