title: Unimolecular Solvolyses in Ionic Liquid: Alcohol Dual Solvent Systems.
abstract: A study was undertaken of the solvolysis of pivaloyl triflate in a variety of ionic liquid:alcohol solvent mixtures. The solvolysis is a kΔ process (i.e., a process in which ionization occurs with rearrangement), and the resulting rearranged carbocation intermediate reacts with the alcohol cosolvent via two competing pathways: nucleophilic attack or elimination of a proton. Five different ionic liquids and three different alcohol cosolvents were investigated to give a total of fifteen dual solvent systems. ¹H-NMR analysis was used to determine relative amounts of elimination and substitution products. It was found, not surprisingly, that increasing the bulkiness of alcohol cosolvent led to increased elimination product. The change in the amount of elimination product with increasing ionic liquid concentration, however, varied greatly between ionic liquids. These differences correlate strongly, though not completely, to the Kamlet-Taft solvatochromic parameters of the hydrogen bond donating and accepting ability of the solvent systems. An additional factor playing into these differences is the bulkiness of the ionic liquid anion.
authors.affiliation: Department of Chemistry, Mills College, 5000 MacArthur Blvd, Oakland, CA 94613, USA. bkochly@mills.edu.
authors.forename: Elizabeth D
authors.initials: ED
authors.lastname: Kochly
authors.affiliation: Department of Chemistry, Mills College, 5000 MacArthur Blvd, Oakland, CA 94613, USA. nlemon@mills.edu.
authors.forename: Nicole Jean
authors.initials: NJ
authors.lastname: Lemon
authors.affiliation: Department of Chemistry, Mills College, 5000 MacArthur Blvd, Oakland, CA 94613, USA. adehlee@mills.edu.
authors.forename: Anne Marie
authors.initials: AM
authors.lastname: Deh-Lee
mesh_terms: D000438:Alcohols / Q000737:chemistry*; D006860:Hydrogen Bonding; D052578:Ionic Liquids / Q000737:chemistry*; D008698:Mesylates / Q000737:chemistry*; D011522:Protons; D012995:Solubility
chemical_list: D000438:Alcohols; D052578:Ionic Liquids; D008698:Mesylates; D011522:Protons
keywords: Kamlet–Taft parameters; carbocation; dual solvent; green chemistry; hydrogen bonding; ionic liquids; nucleophile; organic synthesis; solvolysis