Ripon College, Watertown, WI 53094
SUBSTITUENT EFFECTS ON COORDINATINO ENERGIES OF ALKENES AND ALKYNES TO GOLD AND PALLADIUM CATALYSTS, Kylun. T. Steggall, Joseph Scanlon.* Ripon College, Ripon Chemistry Department, Ripon Wisconsin, 54971. Scanlonj@ripon.edu.
A green synthesis of allyl vinyl ethers is sought after because they are a widely used molecules that can undergo a Claisen rearrangement to form carbon-carbon bonds. A possible green synthesis was investigated experimentally using chloride(dimethylsulfide)gold(I) and dichloro(triphenylphosphine)palladium(II) as the catalysts in the presence of reactants hexyne and allyl alcohol, but the desired product was not obtained. It was suggested that the catalysts were binding to the allyl alcohol and not the alkyne, thereby prohibiting the desired product from forming. This research used computational methods to investigate coordination energies of substituted and unsubstituted allyl alcohol and alkynes. The addition of substituents was utilized to get alkyne to bind more favorably and to get allyl alcohol to bind less favorably to the catalysts. The B3LYP density functional was utilized for all calculations; however, M06 was also used for select calculations. The 6-31G(d) basis set was used for all non-metal atoms and the Stuttgart effective core potential and basis set was used for gold and palladium for all calculations submitted containing those atoms. Substituted ethyne, butyne and allyl alcohol were investigated along with unsubstituted ethyne through decyne. The functional groups that were used for substitution were,-CH3, -OCH3, -NH2, -Cl, -F, -CN, -NO and -N(CH3)2. The results suggested that coordination energy increases as the carbon chain length increases up to a six carbon chain where it plateaus, with hexyne coordinating at -54.06 kcal/mol. Coordination energy of butyne was increased to
-56.76 kcal/mol using 1, 4-bis,dimethylamine-butyne. Unsubstituted allyl alcohol coordinated to the gold catalyst at -53.39 kcal/mol and the coordination energy was decreased to -39.66 kcal/mol by using cis-chloro-allyl alcohol. This suggests that an unsubstituted hexyne and cis-chloro-allyl alcohol be used in the presence of the gold catalyst to obtain the desired product.
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