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Title: Kinetic and thermodynamic study of the reduction of 1,1-diphenylethylene by a thermally frustrated diethyl ether-BCF Lewis pair

Abstract

The reaction enthalpy and rate of reduction of 1,1-diphenylethylene (DPE) by the Frustrated Lewis pair formed between tris-pentafluorophenylborane (BCF) and diethyl ether (Et₂O) in dichloromethane have been determined by mixing calorimetry. At 50 °C and 13.6 atm hydrogen a 0.08 M solution of DPE is reduced to 1,1-diphenylethane in the presence of 1 equivalent BCF and 0.8 equivalents Et₂O in 40 minutes. NMR spectroscopy showed >99% conversion to the reduced product. The rate of conversion of the olefin to the alkane as monitored by the time dependent heat flow showed a linear dependence on the free Et₂O and BCF concentration. Integration of the heat flux provides a measure of the reaction enthalpy of ΔH ca. -116±4 kJ/mol for the reaction Ph₂C=CH₂+H2→Ph₂CHCH₃. The equilibrium constant for dative adduct formation, Et₂O+BCF↔Et₂O—BCF, was determined as a function of temperature by ¹⁹F NMR spectroscopy and provided an experimental measure of the enthalpy, ΔH = -54.6±3.3 kJ/mol⁻¹ and entropy, ΔS=-154±13 Jmol⁻¹ K⁻¹, for dative bond formation in DCM. Extrapolation of the van’t Hoff plot to 50 ºC provides K eq that is used to estimate the concentration of free BCF and Et₂O available to activate hydrogen. This work was supported by the US Department ofmore » Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences. Pacific Northwest National Laboratory (PNNL) is a multiprogram national laboratory operated for DOE by Battelle.« less

Authors:
;
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1184967
Report Number(s):
PNNL-SA-106257
KC0302010
DOE Contract Number:
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Israel Journal of Chemistry, 55(2):196-201
Country of Publication:
United States
Language:
English

Citation Formats

Whittemore, Sean M., and Autrey, Thomas. Kinetic and thermodynamic study of the reduction of 1,1-diphenylethylene by a thermally frustrated diethyl ether-BCF Lewis pair. United States: N. p., 2015. Web. doi:10.1002/ijch.201400142.
Whittemore, Sean M., & Autrey, Thomas. Kinetic and thermodynamic study of the reduction of 1,1-diphenylethylene by a thermally frustrated diethyl ether-BCF Lewis pair. United States. doi:10.1002/ijch.201400142.
Whittemore, Sean M., and Autrey, Thomas. Sun . "Kinetic and thermodynamic study of the reduction of 1,1-diphenylethylene by a thermally frustrated diethyl ether-BCF Lewis pair". United States. doi:10.1002/ijch.201400142.
@article{osti_1184967,
title = {Kinetic and thermodynamic study of the reduction of 1,1-diphenylethylene by a thermally frustrated diethyl ether-BCF Lewis pair},
author = {Whittemore, Sean M. and Autrey, Thomas},
abstractNote = {The reaction enthalpy and rate of reduction of 1,1-diphenylethylene (DPE) by the Frustrated Lewis pair formed between tris-pentafluorophenylborane (BCF) and diethyl ether (Et₂O) in dichloromethane have been determined by mixing calorimetry. At 50 °C and 13.6 atm hydrogen a 0.08 M solution of DPE is reduced to 1,1-diphenylethane in the presence of 1 equivalent BCF and 0.8 equivalents Et₂O in 40 minutes. NMR spectroscopy showed >99% conversion to the reduced product. The rate of conversion of the olefin to the alkane as monitored by the time dependent heat flow showed a linear dependence on the free Et₂O and BCF concentration. Integration of the heat flux provides a measure of the reaction enthalpy of ΔH ca. -116±4 kJ/mol for the reaction Ph₂C=CH₂+H2→Ph₂CHCH₃. The equilibrium constant for dative adduct formation, Et₂O+BCF↔Et₂O—BCF, was determined as a function of temperature by ¹⁹F NMR spectroscopy and provided an experimental measure of the enthalpy, ΔH = -54.6±3.3 kJ/mol⁻¹ and entropy, ΔS=-154±13 Jmol⁻¹ K⁻¹, for dative bond formation in DCM. Extrapolation of the van’t Hoff plot to 50 ºC provides Keq that is used to estimate the concentration of free BCF and Et₂O available to activate hydrogen. This work was supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences. Pacific Northwest National Laboratory (PNNL) is a multiprogram national laboratory operated for DOE by Battelle.},
doi = {10.1002/ijch.201400142},
journal = {Israel Journal of Chemistry, 55(2):196-201},
number = ,
volume = ,
place = {United States},
year = {Sun Feb 01 00:00:00 EST 2015},
month = {Sun Feb 01 00:00:00 EST 2015}
}