Presentation Title

A Study of Molybdenum Catalysts for Deoxydehydration of Vicinal Diols

Faculty Mentor

Alex John

Start Date

17-11-2018 9:45 AM

End Date

17-11-2018 10:00 AM

Location

C327

Session

Oral 2

Type of Presentation

Oral Talk

Subject Area

physical_mathematical_sciences

Abstract

The race to find efficient methods of obtaining renewable chemicals has been gaining traction in the past decade with the increasing scarcity of petroleum-based chemicals. One important chemical class derived from petroleum is alkenes, which is a platform chemical and is used in a wide variety of useful reactions. Recently, researchers have been developing methods to convert biomass-derived material into alkenes. One method to defunctionalize biomass-derived material is by utilizing deoxydehydration (DODH) reactions. This reaction utilizes a metal catalyst and a reductant to convert vicinal diols, which are abundant in biomass such as cellulose, into olefins. Although extensive research has shown that rhenium catalysts may be used in a DODH reaction to obtain up to 60% alkene yields depending on reaction conditions, it is a very costly and scarce resource. Molybdenum on the other hand, is much more cost effective and has potential to be comparable in reactivity to Rhenium when supported with a ligand. We have explored the potential of molybdenum complexes supported over ancillary ligands in catalyzing the DODH reaction. Through this process, we have identified catalytically active molybdenum complexes, as well as successfully identified ligand effects in modulating catalytic activity.

Summary of research results to be presented

To begin with, we have synthesized seven tridentate ligands by Mannich condensation. The first ligand was created by Mannich condensation of 2-aminomethylpyridine and 2-tert-butyl-4-methylphenol. However this ligand performed poorly in the DODH reaction, yielding only 1% styrene. To better understand ligand properties, we made modifications to the structure and evaluated those effects in DODH reactions. The following complexes were obtained by removing one of the phenolate arms and the pyridyl donor. By making these changes, we obtained improved styrene yields of 10 and 30% respectively. So far, we have experimented with, in total, seven different molybdenum complexes, at 10 molar percent. After modification of one of these variables at a time, we are able to observe their individual effects on DODH reactivity and we have seen improved styrene yields of up to 40%. In conclusion, by using 1-phenyl,1-2 ethanediol as the substrate and triphenylphosphene as the reductant, we had varying styrene yields of up to 40% on a 10 mol% complex scale.

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Nov 17th, 9:45 AM Nov 17th, 10:00 AM

A Study of Molybdenum Catalysts for Deoxydehydration of Vicinal Diols

C327

The race to find efficient methods of obtaining renewable chemicals has been gaining traction in the past decade with the increasing scarcity of petroleum-based chemicals. One important chemical class derived from petroleum is alkenes, which is a platform chemical and is used in a wide variety of useful reactions. Recently, researchers have been developing methods to convert biomass-derived material into alkenes. One method to defunctionalize biomass-derived material is by utilizing deoxydehydration (DODH) reactions. This reaction utilizes a metal catalyst and a reductant to convert vicinal diols, which are abundant in biomass such as cellulose, into olefins. Although extensive research has shown that rhenium catalysts may be used in a DODH reaction to obtain up to 60% alkene yields depending on reaction conditions, it is a very costly and scarce resource. Molybdenum on the other hand, is much more cost effective and has potential to be comparable in reactivity to Rhenium when supported with a ligand. We have explored the potential of molybdenum complexes supported over ancillary ligands in catalyzing the DODH reaction. Through this process, we have identified catalytically active molybdenum complexes, as well as successfully identified ligand effects in modulating catalytic activity.