Molybdenum Catalysts based on Salan Ligands for the Deoxydehydration Reaction

29 March 2024, Version 1


Dioxomolybdenum complexes based on salan ligands have been evaluated for their potential in catalyzing the deoxydehydration (DODH) reaction. The DODH reaction is a formal reduction that converts vicinal diols into olefins using an oxometal catalyst and a sacrificial reductant. The reaction holds enormous potential in transforming biomass-derived molecules into platform chemicals. This study evaluated 20 molybdenum complexes supported by salan ligands in the DODH reaction with the goal of establishing structure-activity relationships. Catalyst screenings were performed using styrene glycol as a model substrate and 1-10 mol% loading of the molybdenum complexes at 170 oC producing styrene in up to 54% yield. Aliphatic diols and meso-/R,R-hydrobenzoin were also converted to the corresponding alkenes in moderate to good yields that are comparable to previously reported molybdenum catalysts. A bio-derived glycol, (+)−diethyltartrate, could be converted to the alkene product (diethyl fumarate) in >98% yield using 10 mol% catalyst. A high yield of diethyl fumarate (78%) was also obtained with Na2SO3 (cheap, readily available, and benign) as reductant. Quite significantly, a 42% yield of diethyl fumarate was also obtained at a 1 mol% catalyst loading which represents a turnover number (TON) of 42; this is one of highest activity in a DODH reaction observed with molybdenum catalysts. The catalytic studies along with preliminary kinetic investigations reveal significant ligand effects: sterically bulky ortho-substituents and electron-withdrawing para-substituents on the phenol arms were found to enhance catalytic activity while a rigid phenyl as well as an ethylene backbone featuring a tertiary amine were observed to impede catalysis.


Salan ligands
structure-activity correlations
green chemistry

Supplementary materials

Supplementary Material
Characterization data for compounds and representative kinetic data.


Comments are not moderated before they are posted, but they can be removed by the site moderators if they are found to be in contravention of our Commenting Policy [opens in a new tab] - please read this policy before you post. Comments should be used for scholarly discussion of the content in question. You can find more information about how to use the commenting feature here [opens in a new tab] .
This site is protected by reCAPTCHA and the Google Privacy Policy [opens in a new tab] and Terms of Service [opens in a new tab] apply.