Bachelor of Science
Major or Concentration
Chemistry (ACS Certified)
Di(2-ethylhexyl) phthalate (DEHP) is a known chiral persistent organic pollutant found in many different consumer products, and the toxicities of its stereoisomers and their metabolites are not well known. To determine their adverse health effects, each enantiomer has to be synthesized. Using lipase PS from Burkholderia cepacia in dichloromethane at 0˚C for 48 hours, 2-ethyl-1-hexyl acetate was obtained in 55% yield (75:25 e.r.), while (R)-2-ethyl-1-hexanol (1) was obtained in 29% yield (96:4 e.r.). The acetate was then hydrolyzed to recover the (S) enriched alcohol (82% yield). The enriched alcohol was acylated a second time to yield (S)-(1) in 39% yield (91:9 e.r.). R-(1) and phthalic anhydride were reacted in 1:3 pyridine/toluene at 100˚C for 2 hours to synthesize (R)-mono(2-ethylhexyl) phthalate ((R)-MEHP) in 50% yield. Difficulty was encountered in separating MEHP from (1) in the reaction mixture, with numerous solvent systems, vacuum distillation, and chemically active extraction attempted without success. The resulting impure (R)-MEHP was reacted with (R)-(1) in the presence of N,N'-diisopropylcarbodiimide and 4-dimethylaminopyridine in dichloromethane for 19 hours at room temperature to synthesize(R,R)- DEHP in 36% yield. Future work will synthesize the other isomers of DEHP, further purify (1), and successfully separate MEHP from (1).
Harris, Lonnie Alexander, "Synthesis of The Stereoismomers of DEHP and MEHP from Kinetically Resolved 2-ethyl-1-hexanol" (2016). Student Research Submissions. 78.