Organic Synthesis in Hot Water

Water-Tolerant Lewis-Acid Catalysts

Lewis acids are generally nefarious for thier violent reaction with anything that has an electron pair. Lithium aluminum hydride, for example, will react vigorously with water.  Historically, this behavior toward water, common to Lewis acids, has advised the use of dry conditions for many transformations using lewis acids as reagents.

The recent development of water-tolerant Lewis Acids is relaxing this requirement, and even reversing it. Many reactions are now able to proceed in aqueous media with the aid of a water-tolerant Lewis Acid (WTLA).

We seek to exploit the advantages of WTLAs in high-temperature water (HTW) media. To date, our work has focused upon determining the kinetics of alkyne hydration and of methoxy deprotection in HTW.

p-Xylene Oxidation

Our lab has played a large role in the development of a novel approach to the synthesis of terephthalic acid from p-xylene. This approach uses MnBr and molecular oxygen in a HTW environment to oxidize the methyl groups of p-xylene. The conventional method, on the other hand, used large amounts of acetic acid with a different catalyst.

We continue our intellectual support of this synthesis with efforts geared at determining the kinetics of this transformation and elucidating the mechanism.

Amide Hydrolysis

The hydrolysis of amides is used as a model for the cleavage of peptide bonds. The reaction involves an acyl-transfer process to water, which is schematically represented below.

Thus far, many investigations have concentrated on the hydrolysis reactivity and kinetics of aliphatic and aromatic monoamides, but no studies have been undertaken on N-alkyl-substituted amides. N-methylacetamide was taken as a model to describe the amide group of a peptide. It is the purpose of this work to investigate the hydrolysis kinetics and mechanisms of inactivated amide in high temperature water and to provide explanations about the factors that influence the reaction kinetics

Fatty Acid Decarboxylation

Natural plant oils and fats comprise saturated and unsaturated fatty acids with carbon numbers between C4 and C24, but more typically around C16 to C18. The naturally occurring triglycerides can be decomposed by hydrolysis in high-temperature water. This step produces free fatty acids in an aqueous medium. Decarboxylation of these fatty acids in HTW provides an approach to produce a renewable hydrocarbon bio-fuel from natural oils and fats.

The decarboxylation of fatty acids is shown below.

The main goal of my research is to identify and evaluate catalysts for fatty acid decarboxylation and then to determine the reaction kinetics. The main challenge in this research is to find a catalyst that is stable and active in HTW.