Bio-inspired heterogeneous isomerization of farnesene: production of an alternative to silicone-based emollients
Date
2020
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Publisher
University of Delaware
Abstract
Silicone emollients are widely used in the cosmetic industry because of their superior smoothing and water-resistant properties. However, the uncertainty about the presumed safety of these synthetic polymers could lead to questioning the responsibility of their ample applications. This thesis proposed to investigate bio-mass derived cyclic sesquiterpenes, which are natural essential oils, as potentially safer alternatives. To overcome the current financial and production rate challenges associated with sesquiterpenes synthesis, a heterogeneous catalyst was employed in a three-step approach. First, farnesene isomers were reacted into bi-and tricyclic sesquiterpenes. In the second step, these polycyclic species were hydrogenated to enhance chemical stability, reducing the allergenic potential of this mixture. Third, the produced chemicals were characterized. For each of these three steps, appropriate reaction conditions had to be determined through a systematic trial and error process. ☐ Using 10% solid phosphoric acid as catalyst, a temperature of 175°C, and a run-time of two hours, compounds similar to the ones produced by enzyme-catalyzed isomerization were obtained in the cyclization reaction. These produced compounds showed an increase in \textit{sphericity} and polycyclic structure relative to their reactants and approached the structure of isododecane, another common hydrocarbon emollient. However, due to the elevated temperatures and the lack of stereoselectivity, a large range of products was produced. This variety imposed a problem on the second step, the hydrogenation, for which complete elimination of the C-C double bonds (with Pd/C) was not achieved. Due to the pandemic effects of the SARS-CoV-2, the laboratory was closed and the third step, the rheological and physicochemical characterization of the final product mixture, could not be completed. Although further research is required, this pioneering research has demonstrated the plausibility and effectiveness of substituting a heterogeneous catalyst for sesquiterpene synthases to produce isododecane-like structures.
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Keywords
Emollient, Farnesene, Heterogeneous Catalyst, Isomerization, Sesquiterpenes, Silicone