Origin of the Regioselectivity in the Aldol Condensation between Hydroxymethylfurfural and Levulinic Acid: A DFT Investigation.
Our previous work demonstrated that hydroxide ion (OH-) was able to catalyze aldol condensation reaction at room temperature between 5-hydroxymethylfurfural (HMF) and levulinic acid (LA). This work identified three primary reaction steps in this condensation reaction using density functional theory (DFT): (1) deprotonation of LA to generate LA ions, (2) LA ions addition at hydroxymethyl site of HMF, and (3) internal dehydration to form the condensation product. The reaction pathway through the C5 of LA forms a linear product that is favored with respect to both energy and configuration in all three elementary reaction steps. This is qualitatively consistent with the phenomenon observed in our previous experiment where the linear form is a main product. Further confirmation comes from the frontier orbital analysis of the transition states in the linear reaction route and explains the regioselectivity of product formation.
Department of Material and Chemical Engineering, Ningbo University of Technology , Ningbo, Zhejiang 315016, China.
Liwei
http://orcid.org/0000-0002-3719-8773
L
Zhao
Department of Chemistry, Prairie View A&M University , Prairie View, Texas 77446, United States.
Nnenna
N
Elechi
Department of Chemistry, Prairie View A&M University , Prairie View, Texas 77446, United States.
Richard
R
Qian
Department of Chemistry, Prairie View A&M University , Prairie View, Texas 77446, United States.
Timila B
TB
Singh
Department of Chemistry, Prairie View A&M University , Prairie View, Texas 77446, United States.
Ananda S
AS
Amarasekara
Department of Chemistry, Prairie View A&M University , Prairie View, Texas 77446, United States.
Hua-Jun
HJ
Fan