Ionic Liquid-Based Deep Eutectic Solvent as Reaction Media for the Thermal Dehydrogenation of Ethylene Diamine-<i>bis</i>-borane
Dhirendra Kumar Mishra, G. Pugazhenthi, Tamal Banerjee
Abstract
This work presents a comparative study between Ionic Liquids (ILs) along with the neoteric IL-based Deep Eutectic Solvents (DESs) for the thermal dehydrogenation of ethylene diamine-bis-borane (EDAB). For the selection of potential reaction media, a screening of the potential DES solvent was carried out using the COnductor-like Screening MOdel Segment Activity Coefficient (COSMO-SAC) model to study the solubility of EDAB in the solvent. On the basis of their obtained Infinite Dilution Activity Coefficient (IDAC) value, the following solvents from the IL and the DES family were selected: 1-butyl-3-methylimidazolium methanesulfonate ([BMIM][MeSO3]) and 1-butyl-3-methylimidazolium methanesulfonate:urea ([BMIM][MeSO3]:[urea]) at a molar ratio of 1:1. The latter is considered a DES owing to the addition of hydrogen bond donor, namely, urea. A 1H–1H Nuclear Overhauser Effect SpectroscopY (NOESY) technique NMR spectrum between [BMIM][MeSO3] and urea was also carried out to elucidate the formation of DES. It was observed that the EDAB/DES system produced 3.2 equiv of hydrogen with a lower induction time when compared to 3.7 equiv of hydrogen at the same temperature (105 °C) for the IL-based solvent. This was also confirmed from the TGA analysis of the reaction mixture. Gas Chromatography (GC) analysis was further performed in order to determine the purity of the released hydrogen gas. 1H NMR characterization of the residual EDAB/DES and EDAB/IL complexes reaffirmed the role of IL and DES as a catalyst medium. 11B NMR analysis was further performed in order to confirm the existence of sp2 boron moieties.