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Grunwald-Winstein Analysis - Isopropyl Chloroformate Solvolysis Revisited
Department of Chemistry, Wesley College, 120 N. State Street, Dover, Delaware 19901-3875, USA
Department of Chemistry and Applied Chemistry, Hanyang University, Ansan, Kyunggi-do, 425-791, Korea
Department of Chemistry and Biochemistry, Northern Illinois University, DeKalb, Illinois 60115-2862, USA
Kevin J. Erdman completed a part of this research under the direction of Dr. Malcolm J. D’Souza, while an undergraduate at the University of Wisconsin-Waukesha County, Waukesha, Wisconsin, USA
* Authors to whom correspondence should be addressed.
Received: 9 February 2009; in revised form: 20 February 2009 / Accepted: 27 February 2009 / Published: 2 March 2009
Abstract: Specific rates of solvolysis at 25 °C for isopropyl chloroformate (1) in 24 solvents of widely varying nucleophilicity and ionizing power, plus literature values for studies in water and formic acid, are reported. Previously published solvolytic rate constants at 40.0 °C are supplemented with two additional values in the highly ionizing fluoroalcohols. These rates are now are analyzed using the one and two-term Grunwald-Winstein Equations. In the more ionizing solvents including ten fluoroalcohols negligible sensitivities towards changes in solvent nucleophilicity (l) and very low sensitivities towards changes in solvent ionizing power (m) values are obtained, evocative to those previously observed for 1-adamantyl and 2-adamantyl chloroformates 2 and 3. These observations are rationalized in terms of a dominant solvolysis-decomposition with loss of the CO2 molecule. In nine of the more nucleophilic pure alchohols and aqueous solutions an association-dissociation mechanism is believed to be operative. Deficiencies in the acid production indicate 2-33% isopropyl chloride formation, with the higher values in less nucleophilic solvents.
Keywords: Solvolysis; solvolysis-decomposition; nucleophilicity; ionizing power; isopropyl chloroformate; chloroformates; Grunwald-Winstein Equation; Linear Free Energy Relationships
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D’Souza, M.J.; Reed, D.N.; Erdman, K.J.; Kyong, J.B.; Kevill, D.N. Grunwald-Winstein Analysis - Isopropyl Chloroformate Solvolysis Revisited. Int. J. Mol. Sci. 2009, 10, 862-879.
D’Souza MJ, Reed DN, Erdman KJ, Kyong JB, Kevill DN. Grunwald-Winstein Analysis - Isopropyl Chloroformate Solvolysis Revisited. International Journal of Molecular Sciences. 2009; 10(3):862-879.
D’Souza, Malcolm J.; Reed, Darneisha N.; Erdman, Kevin J.; Kyong, Jin Burm; Kevill, Dennis N. 2009. "Grunwald-Winstein Analysis - Isopropyl Chloroformate Solvolysis Revisited." Int. J. Mol. Sci. 10, no. 3: 862-879.