TY - JOUR
T1 - The High Performance of Choline Arginate for Biomass Pretreatment Is Due to Remarkably Strong Hydrogen Bonding by the Anion
AU - Karton, Amir
AU - Brunner, Manuel
AU - Howard, Mark J.
AU - Warr, Gregory G.
AU - Atkin, Rob
PY - 2018/3/5
Y1 - 2018/3/5
N2 - The ionic liquid choline arginate [Ch][Arg] is more effective for biomass pretreatment than other choline based amino acid ILs, but the underlying mechanism has been unclear. In the present work we use the high-level CCSD(T)/CBS(MP2) and G4(MP2) thermochemical protocols to probe the H-bonding interactions of [Ch][Arg] with water, and organic functional groups commonly found in biomass. We show that the [Ch][Arg] IL forms unusually strong H-bonding interactions with prototypical H-bond donors. For example, we obtain H-bonding interactions of 76.6, 80.0, and 103.6 kJ mol-1 with water, methanol, and phenol, respectively. Our theoretical results shed light on the capacity of [Ch][Arg] to dissolve biomass, and they demonstrate the importance of ion conformation, in addition to speciation, for IL performance more generally. As a point of reference, we compare the H-bonding interactions of [Ch][Arg] with those of a related IL, choline glycinate ([Ch][Gly]), which does not dissolve biomass as effectively as [Ch][Arg].
AB - The ionic liquid choline arginate [Ch][Arg] is more effective for biomass pretreatment than other choline based amino acid ILs, but the underlying mechanism has been unclear. In the present work we use the high-level CCSD(T)/CBS(MP2) and G4(MP2) thermochemical protocols to probe the H-bonding interactions of [Ch][Arg] with water, and organic functional groups commonly found in biomass. We show that the [Ch][Arg] IL forms unusually strong H-bonding interactions with prototypical H-bond donors. For example, we obtain H-bonding interactions of 76.6, 80.0, and 103.6 kJ mol-1 with water, methanol, and phenol, respectively. Our theoretical results shed light on the capacity of [Ch][Arg] to dissolve biomass, and they demonstrate the importance of ion conformation, in addition to speciation, for IL performance more generally. As a point of reference, we compare the H-bonding interactions of [Ch][Arg] with those of a related IL, choline glycinate ([Ch][Gly]), which does not dissolve biomass as effectively as [Ch][Arg].
KW - CCSD(T)
KW - G4(MP2) theory
KW - Ionic liquids
UR - http://www.scopus.com/inward/record.url?scp=85043333888&partnerID=8YFLogxK
U2 - 10.1021/acssuschemeng.7b04489
DO - 10.1021/acssuschemeng.7b04489
M3 - Article
AN - SCOPUS:85043333888
VL - 6
SP - 4115
EP - 4121
JO - ACS Sustainable Chemistry and Engineering
JF - ACS Sustainable Chemistry and Engineering
SN - 2168-0485
IS - 3
ER -