A G. C./M. S. study of the reaction and decomposition products of pentafluorophenyl-grignard and lithium reagents
Abstract
Decomposition and side reactions of, and the synthetic
use of, pentafluorophenylmagnesium bromide and pentafluorophenyllithium
have been investigated using G,C9/M.S,
techniques• Their reactions with reagents such as CgF^X
(X - H, F, CI, Br, 1), C6F4X2 (X - H, CI)f C6F3C13, C6H6.
(CgX5)3P (X = H, F), (C6X5)3P=0 (X = H, F), (CgX5)Si (CH3)3
(X = H, F) and (CH0K SiCl , n = 1,2, in ether or
ether/n-hexane were studied•
In addition to the principal reaction of synthetic
use, namely the replacement of a halogen by a pentafluorophenyl
group, two types of side reactions were observed*
These were (i) intermolecular loss of LiF via a nucleophilic
substitution, and (ii) intramolecular loss of LiF, followed
by the addition of either inorganic salts such as lithium
or magnesium halides, or organometal compounds such as
organolithium or organo-Grigaard*
G.C«/M.S. techniques were routinely employed to study
complicated reaction mixtures. Although mass spectrometry
alone has disadvantages for the identification of isomers,
deduction of the most probable pathway often helps overcome
this problem.