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Chlorination of ammonia and aliphatic amines by Cl 2 : DFT study of medium and substituent effects
Author(s) -
Vrček Valerije,
Meštrić Hrvoje
Publication year - 2009
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.1425
Subject(s) - chemistry , substituent , amine gas treating , computational chemistry , molecule , density functional theory , ammonia , transition state , alkyl , reaction mechanism , solvent effects , solvent , reactivity (psychology) , medicinal chemistry , organic chemistry , catalysis , medicine , alternative medicine , pathology
The mechanism of chlorination of ammonia and aliphatic amines by Cl 2 was studied by quantum‐chemical calculations using a series of DFT functionals. Three different reaction pathways were considered for the reaction between Cl 2 and NH 3 in the gas phase. Several intermediates and transition state structures, not described earlier, were located on the corresponding potential energy surface. It is calculated that the reaction field effects (SCIPCM) on the chlorination is much less pronounced than the effect of a specific solvent interaction which was modeled by an explicit water molecule. It is also found that the calculated energy barrier and the reaction free energy of the chlorination of different amines are dependent on the alkyl‐substituent effects. With increase in the basicity of amine, the chlorination reaction becomes more feasible. Calculated geometries of intermediates and overall reaction energetics are significantly influenced by the method for a treatment of electron correlation (DFT vs . MP2), and by the fraction of HF exchange ( χ ) in DFT functionals. With increase in the χ in the corresponding functional, the DFT results approach those obtained at the MP2 level, and are closer to experimental values, as well. Copyright © 2008 John Wiley & Sons, Ltd.