title: The role of CS₂ in CS₂/NMP mixed solvent in weakening the hydrogen bond of OH-N in coal: a DFT investigation.
abstract: The interaction processes of trace amounts of N-methyl-2-pyrrolidinone (NMP), CS(2)/NMP (1:1 by volume) and pure NMP solvent with the hydrogen bond of OH⋯N in coal were constructed and simulated by density functional theory methods. The distances and bond orders between the main related atoms, and the hydrogen bond energy of OH⋯N were calculated. The calculated results show that pure NMP solvent does not weaken the hydrogen bond of OH⋯N in coal. However, trace amounts of NMP and CS(2)/NMP (1:1 by volume) have a strong capacity to weaken the hydrogen bond of OH⋯N in coal. The H2-N3 distances are elongated from 1.87 Å to 3.80 Å and 3.44 Å, the bond orders of H2-N3 all disappear, and the corresponding hydrogen bond energies of OH⋯N in coal decrease from 45.72 kJ mol(-1) to 7.06 and 11.24 kJ mol(-1), respectively. These results show that CS(2) added to pure NMP solvent plays an important role in releasing the original capacity of NMP to weaken the hydrogen bond of OH⋯N in coal, in agreement with experimental observations.
authors.affiliation: Key Laboratory of Coal Science and Technology of Ministry of Education and Shanxi Province, Taiyuan University of Technology, Taiyuan, 030024 Shanxi, China. quantumtyut@126.com
authors.forename: Baojun
authors.initials: B
authors.lastname: Wang
authors.forename: Liping
authors.initials: L
authors.lastname: Wang
authors.forename: Riguang
authors.initials: R
authors.lastname: Zhang
authors.forename: Lixia
authors.initials: L
authors.lastname: Ling
mesh_terms: D002246:Carbon Disulfide / Q000737:chemistry*; D003031:Coal; D006860:Hydrogen Bonding; D008958:Models, Molecular; D011760:Pyrrolidinones; D012997:Solvents / Q000737:chemistry
chemical_list: D003031:Coal; D011760:Pyrrolidinones; D012997:Solvents; C038678:N-methylpyrrolidone; D002246:Carbon Disulfide