Halogen Free: Functionalized Bis(salicylato)borate Based Ionic Liquids
Hrishikesh CHOWDHURY1, Oleg ANTZUTKIN1
1Luleå University of Technology, Lulea, Sweden
1Lulea University of Technology, Lulea, Sweden
Halogen Free: Functionalized Bis(salicylato)borate Based Ionic Liquids
Hrishikesh Chowdhury* and Oleg N. Antzutkin
Chemistry of Interfaces, Luleå University of Technology, SE-97187 Luleå, Sweden
hrishikesh.chowdhury@associated.ltu.se; Oleg.Antzutkin@ltu.se
Non-halogenated orthoborate-based ionic liquids, including bis(salicylato)borate, [BScB]-, based ionic materials (IM), are in a research focus both as components of electrolytes in battery applications and as additives to lubricants. The notable thing is that the most of bis(salicylato)borate anion-based IMs reported so far contain salicylic acid and/or salicylate anion as principal impurities up to 10-20 mol% (as estimated from 13C NMR spectra in ESI of reported works). Such impurities, which are hydrophobic and rather difficult to get rid from samples of ionic materials, do significantly alter density, viscosity, thermal stability, electrical conductivity and other physico-chemical properties of the final IM products.
Herein, we report on protocols for purification of sodium salts of the named anions and for metathesis reactions, which secure >98-99 mol% pure bis(salicylato)borate based ionic materials. We prepared a library of sodium salts of methyl- and methyloxy-functionalised bis(salicylato)borate anions and then, IMs with these anions and tetraalkyl phosphonium cations and compared physico-chemical properties of these IMs.
"The Kempe Foundation in memory of J. C. and Seth M. Kempe is gratefully acknowledged for the financial support in the form of a stipend for H.C (Grant No. SMK21-0073). O.A. acknowledges the Swedish Foundation for Strategic Research (project EM16-0013) for the financial support."