Thermal Decomposition Mechanisms of Alkylimidazolium Ionic Liquids with CN-containing Anions
Abstract
Due to the unusually high heats of vaporization of room-temperature ionic liquids (RTILs), volatilization of RTILs through thermal decomposition and vaporization of the decomposition products can be significant. Upon heating of these RTILs in vacuum, their gaseous products were detected experimentally via tunable vacuum ultraviolet photoionization mass spectrometry performed at the Chemical Dynamics Beamline 9.0.2 at the Advanced Light Source. Experimental evidence for di- and tri-alkylimidazolium cations and nitrile containing anions indicates thermal decomposition occurs through two pathways: deprotonation of the cation by the anion, and dealkylation of the imidazolium cation by the anion. Additional evidence supporting these mechanisms was obtained using thermal gravimetric analysis/mass spectrometry, gas chromatography/mass spectrometry and temperature-jump infrared spectroscopy. In order to predict the overall thermal stability in these ionic liquids, the ability to accurately calculate both the basicity of the anions and their nucleophilicity in the ionic liquid is critical. Both gas phase and condensed phase (polarizable continuum model) density functional theory calculations provide support for the decomposition mechanisms and a means to determine thermal stabilities for ionic liquids in general.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 01, 2014
- Accession Number
- ADA622792
Entities
People
- Adam C. Schenk
- Amir Golan
- Anna J. Sheppard
- Christine J. Koh
- Ghanshyam L Vaghjiani
- Gregory R. Yandek
- John Maciejewski
- Stephen R. Leone
- Steven D Chambreau
Organizations
- Air Force Research Laboratory