Pentakis(trifluoromethyl)phenyl, a sterically crowded and electron-withdrawing group: synthesis and acidity of pentakis(trifluoromethyl)benzene, -toluene, -phenol, and -aniline | Health & Environmental Research Online (HERO)

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Citation
Tags

HERO ID

2882510

Reference Type

Journal Article

Title

Pentakis(trifluoromethyl)phenyl, a sterically crowded and electron-withdrawing group: synthesis and acidity of pentakis(trifluoromethyl)benzene, -toluene, -phenol, and -aniline

Author(s)

Kütt, A; Movchun, V; Rodima, T; Dansauer, T; Rusanov, EB; Leito, I; Kaljurand, I; Koppel, J; Pihl, V; Koppel, I; Ovsjannikov, G; Toom, L; Mishima, M; Medebielle, M; Lork, E; Röschenthaler, GV; Koppel, IA; Kolomeitsev, AA

Year

2008

Is Peer Reviewed?

Yes

Journal

Journal of Organic Chemistry
ISSN: 0022-3263
EISSN: 1520-6904

Volume

Issue

Page Numbers

2607-2620

Language

English

PMID

18324831

DOI

10.1021/jo702513w

Web of Science Id

WOS:000254544800016

URL

http://://WOS:000254544800016
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Abstract

A general route to functionalized pentakis(trifluoromethyl)phenyl (C6(CF3)5) derivatives, promising building blocks for designing novel stable carbenes, radical species, superacids, weakly coordinating anions and other practically and theoretically useful species, is presented. This pertrifluoromethylation route proceeds via conveniently pregenerated (trifluoromethyl)copper (CF3Cu) species in DMF, stabilized by addition of 1,3-dimethyl-2-imidazolidinone (DMI). These species react with hexaiodobenzene at ambient temperature to give the potassium pentakis(trifluoromethyl)phenoxide along with hexakis(trifluoromethyl)benzene and pentakis(trifluoromethyl)benzene in a combined yield of 80%. A possible reaction pathway explaining the formation of pentakis(trifluoromethyl)phenoxide is proposed. Pentakis(trifluoromethyl)phenol gives rise to easily functionalized pentakis(trifluoromethyl)chlorobenzene and pentakis(trifluoromethyl)aniline. Pertrifluoromethylation of pentaiodochlorobenzene and pentaiodotoluene allows straightforward access to pentakis(trifluoromethyl)chlorobenzene and pentakis(trifluoromethyl)toluene, respectively. XRD structures of several C6(CF3)5 derivatives were determined and compared with the calculated structures. Due to the steric crowding the aromatic rings in all C6(CF3)5 derivatives are significantly distorted. The gas-phase acidities (Delta Gacid) and pKa values in different solvents (acetonitrile (AN), DMSO, water) for the title compounds and a number of related compounds have been measured. The origin of the acidifying effect of the C6(CF3)5 group has been explored using the isodesmic reactions approach.