Presentation Title

Mechanistic Challenges in Transesterification During the Synthesis of Hypophosphite Esters

Faculty Mentor

Sylvine Deprele

Start Date

17-11-2018 8:15 AM

End Date

17-11-2018 8:30 AM

Location

C335

Session

Oral 1

Type of Presentation

Oral Talk

Subject Area

physical_mathematical_sciences

Abstract

One of the largest oil spills, the Deep Horizon Oil Spill, occurred in April 2010 and the more recent Santa Barbara Oil Spill in May 2015. Oil surfactants are a cleanup method that involve amphipathic organic molecules that form micelles and separate the large mass of oil into smaller droplets. This allows for bioremediation and our objective is to synthesize an environmentally friendly, phosphorus-based surfactant through a three-step synthesis process. Our three-step synthesis involves hypophosphite esters and a palladium-catalyzed hydrophosphinylation with bromoalkenes, followed by a reaction with a tertiary amine. During the first step, a transesterification mechanism occurs with the nucleophile attack of the desired alcohol chain to hypophosphous acid. Long chain alcohols are desired to produce the ideal characteristics of a surfactant, thus long chain alcohols were observed. To further gain a better insight of the diversity of long chains we looked at three different parameters that may have an effect on our product yield: solvent study, equivalence study and a time study. Our results showed that the primary alcohol nonanol with the solvent toluene at 4 equivalence resulted in a product yield of 67%, which was higher than the solvent cyclohexane with a product yield of 55%. After further investigation it was discovered that our transesterification produced 52% product yield in the first ten minutes, and at one hour our product yield was only at 54%. Alcohol classes were also examined, primary alcohol dodecanol product yield was 76%. Our secondary alcohol 2-octanol had a product yield of 67%, while tertiary alcohol 2-methyl-2 propanol product yield was 41%.Based on our data we found that primary alcohols produces higher product yields due to less branching and steric hindrance than secondary and tertiary alcohols. We are currently working on optimizing our product yields before proceeding with our second synthesis step.

Summary of research results to be presented

An alcohol equivalence study was performed, results found that nonanol at 4 equivalence had a product yield of 60% compared to nonanol at 2 equivalence with a product yield of 35%. Subsequently a solvent study was conducted with nonanol with the solvent toluene at 4 equivalence with a product yield of 67%, which was higher than the solvent cyclohexane with a product yield of 55%. Using the primary alcohol nonanol a time study was performed it was discovered that our transesterification produced 52% product yield in the first ten minutes, while at one hour our product yield was only at 54%. Lastly, alcohol classes were also examined, long chain primary alcohol, dodecanol, produced a yield of 76%. Secondary alcohol 2-octanol had a product yield of 67%, while tertiary alcohol 2-methyl-2 propanol product yield was 41%. Based on our data we found that primary alcohols produces higher product yields due to less branching and steric hindrance than secondary and tertiary alcohols

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Nov 17th, 8:15 AM Nov 17th, 8:30 AM

Mechanistic Challenges in Transesterification During the Synthesis of Hypophosphite Esters

C335

One of the largest oil spills, the Deep Horizon Oil Spill, occurred in April 2010 and the more recent Santa Barbara Oil Spill in May 2015. Oil surfactants are a cleanup method that involve amphipathic organic molecules that form micelles and separate the large mass of oil into smaller droplets. This allows for bioremediation and our objective is to synthesize an environmentally friendly, phosphorus-based surfactant through a three-step synthesis process. Our three-step synthesis involves hypophosphite esters and a palladium-catalyzed hydrophosphinylation with bromoalkenes, followed by a reaction with a tertiary amine. During the first step, a transesterification mechanism occurs with the nucleophile attack of the desired alcohol chain to hypophosphous acid. Long chain alcohols are desired to produce the ideal characteristics of a surfactant, thus long chain alcohols were observed. To further gain a better insight of the diversity of long chains we looked at three different parameters that may have an effect on our product yield: solvent study, equivalence study and a time study. Our results showed that the primary alcohol nonanol with the solvent toluene at 4 equivalence resulted in a product yield of 67%, which was higher than the solvent cyclohexane with a product yield of 55%. After further investigation it was discovered that our transesterification produced 52% product yield in the first ten minutes, and at one hour our product yield was only at 54%. Alcohol classes were also examined, primary alcohol dodecanol product yield was 76%. Our secondary alcohol 2-octanol had a product yield of 67%, while tertiary alcohol 2-methyl-2 propanol product yield was 41%.Based on our data we found that primary alcohols produces higher product yields due to less branching and steric hindrance than secondary and tertiary alcohols. We are currently working on optimizing our product yields before proceeding with our second synthesis step.