Developing green processes for the conversion of biobased materials into pyrones
Eric . Cochran
The work disclosed in this dissertation implements bio-based material for new synthetic applications. The synthetic applications are corrosion inhibitors, plasticizers, and block copolymers. Triacetic Acid Lactone (TAL) is a bio-based molecule fermented from Saccharmyces cerevisiae. In the first chapter, we discuss the conversion of triacetic acid lactone to corrosion inhibitors. The synthesis utilizes a nucleophilic heterocycle undergoing conjugate addition with brominated TAL producing a corrosion inhibitor. Successful corrosion inhibitors were synthesized in moderate to good yields. The highest corrosion inhibitor efficiency was 88% for newly developed corrosion inhibitors.
In the second chapter we developed a methodology to generate -pyrones. This moiety was formed by a [3+3] reaction between a 1,3 dicarbonyl and dihaloacryloyl chloride. Bicyclic -pyrones could be transformed into 5-hydroxychomones by aromatization in good yields.
In the third chapter, we found new applications for citric and malic acid mixtures (similar to those found in fruit) by converting them into plasticizers. Citric and malic acid could be reacted together to form an -pyrone diacid in 76% yield. The reaction was conducted in concentrated sulfuric acid. The esters of citric and malic acid could also be reacted together to afford the diester pyrone.
In the fourth chapter, we combined anionic polymerization with reversible addition fragmentation chain transfer RAFT polymerization by the development of macro-chain transfer agent. The conversion of anionic polystyrene to block acrylic copolymers had an efficiency as high as 97%. This was completed by coupling -bromoisobutryl bromide, followed by atom-transfer radical addition fragmentation transfer with bis(thiobenzyl)disulfide to add the chain transfer agent functionality. The methodology of combining anionic polymerization with RAFT polymerization gave the highest blocking efficiency known in the literature.