Premium
Bis‐ and Oligo(trifluoromethyl)benzenes: Hydrogen/Metal Exchange Rates and Gas‐Phase Acidities
Author(s) -
Schlosser Manfred,
Mongin F.,
Porwisiak Jacek,
Dmowski Wojciech,
Büker Heinz H.,
Nibbering Nico M. M.
Publication year - 1998
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/(sici)1521-3765(19980710)4:7<1281::aid-chem1281>3.0.co;2-i
Subject(s) - trifluoromethyl , chemistry , steric effects , deprotonation , aryl , metal , medicinal chemistry , base (topology) , inorganic chemistry , gas phase , hydrogen , polar effect , ion , stereochemistry , organic chemistry , mathematical analysis , alkyl , mathematics
To what extent do trifluoromethyl groups stabilize electron excess? An unequivocal answer was deduced from gas‐phase equilibration between two acid/base couples, one of them composed of an arene carrying zero, one, two, three trifluoromethyl substituents and the corresponding aryl anion. Depending on its distance from the anionic site, a CF 3 unit stabilizes the latter by up to 13 kcal mol −1 , and the effects of two or more substituents are additive. On the other hand, when strong bases are employed in solution to generate organometallic species under irreversible conditions, the relative rates of deprotonation are unpredictable since steric hindrance exerted by the CF 3 groups and side reations now play a crucial role.