Large oil spills in the ocean are catastrophic events which pose a threat to the environment and marine life. This project was inspired by the Deepwater Horizon oil spill that occurred in April 2010, and is relevant to the recent Santa Barbara oil spill from May 2015. Currently, oil dispersants containing carbon-based surfactants are commonly used for clean-up. Surfactants help the oil disperse into droplets, encouraging more efficient bioremediation by microorganisms. Our objective is to synthesize novel phosphorus-based surfactants. Phosphorus is a vital element for life, so it is anticipated that phosphorus-based surfactants could increase the growth of bioremediating organisms and generate phosphates as bi-products as they decompose, thus providing a more environmentally friendly alternative. Our three-step synthetic route involves hypophosphite esters and a palladium-catalyzed hydrophosphinylation with bromoalkenes, followed by a reaction with a tertiary amine. The Dean-Stark method, which allows for the removal of water during esterification, has shown high yields of hypophosphite esters in step one of our project with 31P crude NMR yields ranging from 80-95% using primary and secondary alcohols such as heptanol and 2-octanol, respectively, in toluene. Results from the Pd-catalyzed hydrophosphinylation between the heptyl ester and 5-bromo-1-pentene show that our target product is synthesized with two conformations due to, we believe, the unselective addition of the bromoalkene onto the phosphorus center. Purification began with a work-up involving a series of washes, followed by flash chromatography, and TLC analysis of the collected fractions. Similar fractions were then combined, and two compounds were isolated. Proton and phosphorus NMR spectra reveal that the compounds obtained are most likely the expected 2 isomers of the heptyl (5-bromo-pentyl) phosphinate. Further analysis with higher power NMR will be conducted to clearly identify the isolated compounds and the scope of the reaction will be expended to various classes of esters.

Pd-Catalyzed hydrophosphinylation: The second step in the synthesis of phosphorus-based surfactants

251st National Meeting (2016)

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