Use of Linear Free Energy Relationships (LFERs) to elucidate the mechanisms of reaction of a γ-methyl-β-alkynyl and an ortho-substituted aryl chloroformate ester.
The specific rates of solvolysis of 2-butyn-1-yl-chloroformate (1) and 2-methoxyphenyl chloroformate (2) are studied at 25.0 °C in a series of binary aqueousorganic mixtures. The rates of reaction obtained are then analyzed using the extended Grunwald-Winstein (G-W) equation and the results are compared to previously published G-W analyses for phenyl chloroformate (3), propargyl chloroformate (4), p-methoxyphenyl choroformate (5), and p-nitrophenyl chloroformate (6). For 1, the results indicate that dual side-by-side addition-elimination and ionization pathways are occurring in some highly ionizing solvents due to the presence of the electron-donating γ-methyl group. For 2, the analyses indicate that the dominant mechanism is a bimolecular one where the formation of a tetrahedral intermediate is rate-determining.
Department of Chemistry, Wesley College, 120 N. State Street, Dover, DE 19901, USA.
Malcolm J
MJ
D'Souza
Department of Chemistry, Wesley College, 120 N. State Street, Dover, DE 19901, USA.
Jaci A
JA
Knapp
Department of Chemistry, Wesley College, 120 N. State Street, Dover, DE 19901, USA.
Gabriel A
GA
Fernandez-Bueno
Department of Chemistry and Biochemistry, Northern Illinois University, DeKalb, IL 60115, USA.
Dennis N
DN
Kevill
D000480:Alkynes / Q000737:chemistry*; D000840:Anisoles / Q000737:chemistry*; D004952:Esters; D005561:Formates / Q000737:chemistry*; D007700:Kinetics; D012997:Solvents / Q000737:chemistry*; D013696:Temperature; D013816:Thermodynamics; D014867:Water / Q000737:chemistry
D000480:Alkynes; D000840:Anisoles; D004952:Esters; D005561:Formates; D012997:Solvents; D014867:Water; C083354:chlorocarbonic acid