Isohexide Dinitriles: A Versatile Family of Renewable Platform Chemicals
Jing Wu1,2,3, Shanmugam Thiyagarajan2, Célia Fonseca Guerra4,5
1Co-Innovation Center of Textile Industry, Donghua University, Northern Renmin Road 2999, Shanghai, P.R. China.
Abstract:
Building blocks of isohexides extended by one carbon atom at the 2- or 5-positions are now synthetically accessible by a convenient, selective, base-catalyzed epimerization of the corresponding dinitriles. Kinetic experiments using the strong organic base 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) show that all three possible isohexide dinitrile isomers exist within a dynamic equilibrium. An epimerization mechanism based on density functional theory (DFT) calculations is proposed. Structural identification of all three possible isomers is based on NMR analysis and single crystal x-ray crystallography. DFT calculations confirm that the observed crystal structures are indeed the lowest energy conformers of these isohexide derivatives.
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