AN EXAMINATION OF THE EFFECTS OF EXTENDED CONJUGATION THROUGH POLYCYCLIC SYSTEMS INCORPORATED INTO MONOAZO DYES
AN EXAMINATION OF THE EFFECTS OF EXTENDED CONJUGATION THROUGH POLYCYCLIC SYSTEMS INCORPORATED INTO MONOAZO DYES
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Date
1987-01
Authors
WADA, BONIFACE TYOTSUWE
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Abstract
A systematic investigation has been carried out
into the spectroscopic behaviour of some monoazo dyes
derived from polycyclic systems. Hallas and his students
have previously examined various phenylazo dyes derived
from terminally bridged systems, viz. kairoline (N-methyl-
1,2,3,4-tetrahydroquinoline), N-2-cyanoethyl-l,2,3,4-
tetrahydroquinoline, lilolidine(1,2,5,6-tetrahydro-4HpyrroloC3
,2,1-i ] Iquinoline) and julolidine (2,3,6,7-
tetrahydro-lH,5H-benzo[i j ]quinolizine). The present work
is a continuation of these researches and includes dyes
derived from more complex molecules based on naphthalene
and phenanthrene. Novel azo dyes have also been prepared
by coupling polyclic systems to N,N-diethylaniline in order
to compare their characteristics with the well-documented
properties of simple dialkylamino compounds.
Several useful intermediates have been prepared for
the first time and improved routes to others have been
developed. Thus, l~amino-2-nitronaphthalene was obtained
by direct amination of 2-nitronaphthalene and was found to
be identical with samples obtained by other routes. A pure
sample of 7-nitrotetral-l-one has been prepared and its
oxime has been shown to melt at 170°C in contrast to the
reported value of 150°C. A useful route has been devised
for the preparation of several unsymmetrically disubstituted
9,10-dihydrophenanthrene derivatives and the corresponding
phenanthrene analogues. The dinitration of 9,10-dihydrophenanthrene
affords largely 2,7-dinitro-9,10-dihydrophenanthrene
from which 2-amino-7-nitro-9,10-dihydrophenanthrene
is obtained through selective reduction. The analogous
phenanthrene compound is best obtained by aromatisation
of the dinitro-9,10-dihydro compound followed by selective
reduction.
The electron-donating abilities of four different
couplers have been examined by monitoring the spectral
changes of appropriate dyes in ethanol and in ethanolic
hydrogen chloride. The terminally bridged systems are in
general better electron donors than a simple dialkylamino
group, although dyes derived from N-2-cyanoethyl-l,2,3,4-
tetrahydroquinoline show hypsochromic shifts in ethanol
with respect to the corresponding dialkylamino dyes owing
to the strong electron withdrawing influence of the cyano
group.
Spectral data have also shed light on the complex
question of colour chemical constitution relationships as
well as establishing the halochromism of some of the dyes
in various solvents.
The Pariser-Parr-Pople Molecular Orbital method
with limited configuration interaction (PPP-MO CI) has been
applied to most of the intermediates and the corresponding
dyes for the prediction of molecular properties in the
ground state and in the first singly excited state
Description
Thesis
Submitted in fulfilment of the requirements
for the degree of
DOCTOR OF PHILOSOPHY
by
BONIFACE TYOTSUWE WADA
Department of Colour Chemistry,
University of Leeds,
January, 1978.
Keywords
EXAMINATION,, CONJUGATION,, POLYCYCLIC SYSTEMS,, INCORPORATED,, MONOAZO DYES