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The basicity of substituted N , N ‐dimethylanilines in solution and in the gas phase
Author(s) -
Kaljurand Ivari,
Lilleorg Roman,
Murumaa Algis,
Mishima Masaaki,
Burk Peeter,
Koppel Ivar,
Koppel Ilmar A.,
Leito Ivo
Publication year - 2013
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.2956
Subject(s) - chemistry , substituent , acetonitrile , gas phase , ring (chemistry) , solvent , medicinal chemistry , solvent effects , triphenylamine , phase (matter) , photochemistry , organic chemistry
Basicities of a number of ring‐substituted N , N ‐dimethylanilines (DMA) and some related bases in water, acetonitrile, and THF and in the gas phase have been experimentally determined. Gas‐phase basicities of DMAs and related bases were calculated at DFT B3LYP 6‐311+G** and G3(MP2) levels. Structure–Basicity relationships in these four media were discussed. By comparison of gas‐phase basicity shifts induced by stepwise substitution, starting from ammonia and ending at triphenylamine, it was observed that solvent effects of water and acetonitrile exceed the structural effects on intrinsic basicity. It was shown that the influence of substituents in the phenyl ring on DMA basicity is reduced by two to three times when going from the gas phase into the abovementioned condensed media. In the gas phase, 4‐NO, 4‐NO 2 , 4‐CN, 4‐COMe, and 4‐CHO substituted DMAs protonate on substituent, whereas in solvents, only 4‐NO‐DMA probably protonates on substituent. The sensitivity of DMA basicity toward substitution in the phenyl ring was compared with the related family of phenylphosphazene bases, and it was found that the substituent effect is stronger in DMAs by 1.35 times in acetonitrile, 1.45 times in the gas phase, 2.0 times in THF, and 2.6 times in water. Copyright © 2012 John Wiley & Sons, Ltd.