Synthesis and application of some alkali-clearable azo disperse dyes based on naphthalimide derivatives

Article abstract of DOI:10.1002/jccs.200900150

A series of naphthalimide-based alkali-clearable azo disperse dyes containing a fluorosulfonyl group was synthesized. 4-Fluorosulfonylaniline, 4-fluorosulfonyl-2-nitroaniline and 6-chloro-4-fluorosulfonyl-2-nitroaniline as the diazo components were prepar

Full text of DOI:10.1002/jccs.200900150

Journal of the Chinese Chemical Society, 2009, 56, 1035-1042
1035
Synthesis and Application of Some Alkali-clearable Azo Disperse Dyes
Based on Naphthalimide Derivatives
P. Parvizi,a A. Khosravi,a,* S. Moradiana and K. Gharanjigb
aAmirkabir University of Technology, Department of Polymer Engineering & Color Technology, Tehran-Iran
bInstitute for Colorants, Paint and Coatings, Tehran-Iran
A series of naphthalimide-based alkali-clearable azo disperse dyes containing a fluorosulfonyl group
was synthesized. 4-Fluorosulfonylaniline, 4-fluorosulfonyl-2-nitroaniline and 6-chloro-4-fluorosul-
fonyl-2-nitroaniline as the diazo components were prepared from N-acetylsulfanilyl chloride and were
subsequently coupled with 4-hydroxy-N-3-methoxypropyl-1,8-naphthalimide. The synthesized dyes and
their intermediates were characterized by the use of DSC, FTIR, 1H NMR, 13C NMR, Mass spectroscopy
and UV-visible spectroscopic techniques. Spectrophotometric investigations of prepared dyes in different
solvents were carried out in order to obtain their absorption maxima, molar extinction coefficients and
solvatochromic effects. The obtained dyes were applied to polyester fabric by the HT method and exhib-
ited good leveling, wash and sublimation fastnesses and moderate light fastness. The synthesized dyes
showed that incorporated fluorosulfonyl group to these dyes can be converted to the dyes containing a wa-
ter soluble sulfonate group in the relatively mild alkaline conditions.
Keywords: Disperse dyes; Polyester fabric; Naphthalimide; Alkali-clearable; Dyeing.
1. INTRODUCTION
the dyeing is completed. These particles, which have re-
mained on the surface of the fibers, cause reduction of the
shade brightness as well as the wash and rubbing fast-
nesses.2,3 Therefore, the conventional method of reduction
clearing is necessary for removing these particulates. In
this process the dyed fabric is treated by a solution contain-
ing sodium hydrosulfite, sodium hydroxide and detergent.
Treatment of reduction clearing causes environmental pol-
lution, and increases BOD of the effluents.4,5 Disperse dyes
containing azo groups can also be broken and generate
toxic and carcinogenic aromatic amines according to Eq. 1.
Therefore, elimination of treatment of reduction clearing in
the dyeing polyester process with disperse dyes can signifi-
cantly reduce pollution of environment as well as the costs
of effluent treatments.
In recent decades, production and requirements of
new synthetic dyes for dyeing textile fibers have been con-
siderably decreased because of three reasons. Firstly, the
massive increase in oil prices and subsequent recession of
recent years has hit the dye and textile industries particu-
larly severely.1 Secondly, the introduction of stringent toxi-
cological test requirements for new products and severe
regulations for protecting environment, have made the in-
troduction of new dyes a much less attractive proposition.
Finally, there is the unavoidable fact that there is a natural
limit to the number of dyes needed by the textile industry,
and the current status of dye development is such that fur-
ther improvements in performance and economics of exist-
ing dyes are likely to be minimal.1 These limitations, which
have been performed by the world organizations for de-
creasing pollution of environment, have caused increasing
requirements for manufacturing environmentally friendly
dyes.
Na2S2O4
(1)
Ar1-NH2 + Ar2-NH2
Ar1-N=N-Ar2
Pioneering work on disperse dyes has been researched
to obtain the dyes which leads to the elimination of reduc-
tion clearing process in dyeing polyester fibers.4 Synthe-
sized disperse dyes based on diester, phthalimide and thio-
phene derivatives are groups of these dyes which can be
Disperse dyes are slightly soluble in water, and they
can be applied as a dispersion in water on polyester fibers.
Since disperse dyes have a limited solubility in water, some
particles of dyes may be remained on the fiber surface after
* Corresponding author. Tel: +98-21-64542407; Fax: +98-2166469162; E-mail: A.khosravi@aut.ac.ir

1036 J. Chin. Chem. Soc., Vol. 56, No. 5, 2009
Parvizi et al.
converted to water soluble or colourless compounds in al-
kali media.5-8 Therefore, for substrates which have been
dyed with these dyes, reduction-cleared process can be re-
placed by alkali-cleared process. Another group of this
type is fluorosulfonyl–based alkali-clearable dyes.2,3 In
this type, the fluorosulfonyl group can be converted to the
water soluble SO3Na group according to Eq. 2. Different
substituents with different dyeing properties of these dyes
have been synthesized. In these dyes the diazo component
was an aromatic amine containing of -SO2F group and the
coupling component was a tertiary aromatic amine.
out by the use of the same methods mentioned above.
4-Fluorosulfonyl-2-nitroaniline:
FTIR (cm-1): 1201 (C-N str.), 1403-1514 (NO2 str.
sym. and unsym.), 1559 (C=C str.), 3368-3481 (N-H str.);
1H NMR (CDCl3): d (ppm): 1.59 (2H, NH2), 7-7.03 (1H,
6-H), 7.78-7.9 (1H, 5-H), 8.86 (1H, 3-H); Yield = 33%, m.p
= 150.3 °C.
6-Chloro-4-fluorosulfonyl-2-nitroaniline:
FTIR (cm-1): 759 (C-Cl str.), 1208 (C-N str.), 1409-
1526 (NO2 str. sym. and unsym.), 1552 (C=C str.), 3342-
1
3449 (N-H str.), H NMR (CDCl3): d (ppm) 1.58 (2H,
NH2), 8.09-8.1 (1H, 3-H), 8.81-8.83 (1H, 5-H); Yield =
64%, m.p = 132 °C.
(iii) Preparation of 4-hydroxy-N-3-methoxypropyl-
1,8-naphthalimide as the coupling component was carried
out by the use of acenaphthene as a starting material and
then subsequent reactions such as sulfonation, oxidation,
imidation and hydroxylation were carried out.10
FTIR (cm-1): 1586 (C=C str.), 1642-1688 (C=O str.
(2)
In the present study, a novel series of monoazo dis-
perse dyes based on naphthalimide derivatives containing
of fluorosulfonyl group has been obtained utilizing 4-fluo-
rosulfonylaniline, 4-fluorosulfonyl-2-nitroanialine and 6-
chloro-4-fluorosulfonyl-2-nitroaniline, as the diazo com-
ponents and 4-hydroxy-N-3-propyl-1,8-naphthalimide con-
stituted the coupling component (Fig. 1). The dyes were
then purified and characterized together with their corre-
sponding intermediates by the use of spectroscopic tech-
niques. The prepared dyes were subsequently dyed on
polyester fabric and finally their optical, dyeing and al-
kali-clearable properties were determined.
1
sym. and unsym.), 3276 (OH str.); H NMR (CDCl3): d
(ppm) 2.01-2.03 (2H, CH2), 3.37 (3H, OCH3), 3.42-3.59
(2H, CH2O), 4.27-4.32 (2H, NCH2), 6.73 (1H, O-H), 6.98-
7.01 (1H, 3-H), 7.7-7.75 (1H, 6-H), 8.41-8.44 (1H, 2-H),
8.54-8.58 (1H, 5-H), 8.62-8.64 (1H, 7-H); Yield = 71%,
m.p. = 225 °C.
Preparation of the dyes
(i) Dye 1
4-Fluorosulfonylaniline (10 mmol, 0.175 g) was di-
azotized in solution of hydrochloric acid (3.45 mL) and wa-
ter (35 mL) and sodium nitrite (10 mmol, 0.07 g) at a tem-
perature of 0-5 °C. The saturated of sodium acetate was
added to this solution and the pH value of the diazo liquor
was adjusted to 5-6. The reaction mixture was stirred for 5
hours to complete the reaction.
2. EXPERIMENTAL
2.l. Materials
All compounds used in this study were of analytical
grade unless otherwise stated.
The diazotized 4-fluorosulfonylaniline was added to
a solution containing 10 mmol (0.285 g) of coupling com-
ponent (4-hydroxy-N-3-methoxypropyl-1,8-naphthalimide)
in 20 mL of methoxyethanol. After 4-5 hours the reaction
was completed and the precipitated dye was filtered, washed
with water and dried. The dye was purified by TLC and col-
umn chromatography methods.
2.2. Procedures
(i) Preparation of 4-fluorosulfonylaniline was carried
out by the use of N-acetylsulfanilyl chloride and then sub-
sequent processes such as fluorination, hydrolysis, nitra-
tion and chlorination were carried out according to the
method of Koh et al.9
FTIR (cm-1): 1595 (C=C str.), 3397-3492 (N-H str.);
1H NMR (CDCl3): d (ppm): 4.40 (2H, NH2), 6.72-6.75 (2H,
3-H, 5-H), 7.76-7.79 (2H, 2-H, 6-H), Yield = 63%, m.p =
70 °C.
FTIR (cm-1): 1402 (N=N str.), 1498 (C-N str.), 1620,
1657 (C=O str. Carbonyl sym. and unsym.), 3443 (O-H
str.); 1H NMR (CDCl3): d (ppm) 2.0-2.05 (2H, CH2), 3.35
(3H, OCH3), 3.51-3.55 (2H, CH2O), 4.25-4.30 (2H, NCH2),
7.73-7.78 (H, 6-H), 7.89-7.92 (2H, 3¢-H, 5¢-H), 8.15-8.17
(2H, 2¢-H, 6¢-H), 8.44 (1H, 2-H), 8.65-8.66 (1H, 5-H),
(ii) Preparation of 4-fluorosulfonyl-2-nitroaniline
and 6-chloro-4-fluorosulfonyl-2-nitroaniline were carried

Alkali-clearable Azonaphthalimide Disperse Dyes
J. Chin. Chem. Soc., Vol. 56, No. 5, 2009 1037
Fig. 1. The synthesized dyes and their intermediates.
8.67-8.69 (1H, 7-H), 16.39 (1H, OH); 13C NMR (CDCl3): d
(2C), 130.1, 133.9 (4C), 137.5, 141.4, 150.8, 152.2, 163.1,
(ppm) 21.3, 24.7, 37.2, 41.6, 62.5, 75.8, 94.1, 119.3, 126.7
172.4, 176.9; Yield = 57%, m.p = 216 °C, Mass: 471 m/z.

1038 J. Chin. Chem. Soc., Vol. 56, No. 5, 2009
Parvizi et al.
(ii) Dye 2
tered, washed with water and dried. The dye was purified
by TLC and column chromatography methods.
Diazotization of 4-flourosulfonyl-2-nitroaniline was
carried out with nitrosylsulphuric acid. For this purpose,
4-flourosulfonyl-2-nitroaniline (10 mmol, 0.22 g) was dis-
solved in the solution of acetic acid and propionic acid (4:1,
50 mL) and then it was added to the solution of sodium ni-
trite (10 mmol, 0.07 g) and sulfuric acid (15 mL) at a tem-
perature of 5-10 °C. The reaction mixture was stirred at this
temperature for 3 hours. The obtained clear diazonium salt
solution was used immediately in the coupling reaction.
The pH of the diazonium salt solution was adjusted to 5-6
by adding sodium acetate solution.
FTIR (cm-1): 800 (C-Cl), 1420 (N=N str.), 1620, 1657
(C=O str. Carbonyl sym. and unsym.), 1409, 1531 (NO2 str.
sym. and unsym.), 3435 (O-H str.); 1H NMR (CDCl3): d
(ppm) 2.01-2.03 (2H, CH2), 3.34 (3H, OCH3), 3.55 (2H,
CH2O), 4.27-4.29 (2H, NCH2), 7.79-7.82 (1H, 6-H), 8.26-
8.31 (1H, 2-H), 8.67-8.72 (3H, 3¢-H, 5¢-H, 5-H), 9.03 (1H,
7-H), 16.78 (1H, OH); 13C NMR (CDCl3): d (ppm) 20.4,
23.5, 36.2, 40.3, 61.4, 73.1, 91.9, 118.7, 125.2 (2C), 124.5,
128.6, 133.7, 132.9, 134.1, 137.2, 140.5, 149.8, 151.9,
160.1, 171.3, 175.8; Yield = 61%, m.p = 215 °C, Mass: 550
m/z.
The diazotized 4-flourosulfonyl-2-nitroaniline was
added to a solution containing 10 mmol (0.285 g) of cou-
pling component (4-hydroxy-N-3-methoxypropyl-1,8-naph-
thalimide) in 20 mL of methoxy ethanol. After 13 hours the
reaction was completed and the precipitated dye was fil-
tered, washed with water and dried. The dye was purified
by TLC and column chromatography methods.
(iv) Dye 4
4-Nitroaniline (10 mmol, 0.175 g) was diazotized in
solution of hydrochloric acid (3.45 mL) and water (35 mL)
and sodium nitrite (10 mmol, 0.07 g) at a temperature of 0-5
°C. The reaction mixture was stirred at this temperature for
30 min. The obtained clear diazonium salt solution was
used immediately in the coupling reaction.
FTIR (cm-1): 1408 (N=N str.), 1486 (C-N str.), 1403,
1556 (NO2 str. sym. and unsym.), 1607, 1660 (C=O str.
1
Carbonyl sym. and unsym.), 3427 (O-H str.); H NMR
The diazotized 4-nitroaniline was added to a solution
containing (10 mmol, 0.285 g) of coupling component (4-
hydroxy-N-3-methoxypropyl-1,8-naphthalimide) in 20
mL of methoxyethanol. After 4-5 hours, the reaction was
completed and the precipitated dye was filtered, washed
with water and dried. The dye was purified by TLC and col-
umn chromatography methods. FTIR (cm-1): 1395 (N=N
str.), 1334-1497 (NO2 str. sym. and unsym.), 1605-1653
(C=O str. Carbonyl sym. and unsym.), 3440 (OH str.); 1H
NMR (CDCl3): d (ppm): 2-2.07 (2H, CH2), 3.35 (3H,
OCH3), 3.51-3.56 (2H, CH2O), 4.25-4.3 (2H, NCH2), 7.73-
7.78 (1H, 6-H), 7.83-7.86 (2H, 3¢-H, 5¢-H), 8.4-8.47 (3H,
2¢-H, 6¢-H, 2-H), 8.65-8.69 (2H, 5-H, 7-H), 16.48 (1H,
OH); 13C NMR (CDCl3): d (ppm) 23.5, 27.1, 40.3, 43.7,
60.9, 72.7, 95.2, 121.4, 125.3 (2C), 128.6 (2C), 129.4 (2C),
135.1, 139.3, 150.2, 154.9, 157.1, 164.8, 173.6, 178.1.
Yield = 65%, m.p = 225 °C, Mass: 434 m/z.
(CDCl3): d (ppm) 1.98-2.07 (2H, CH2), 3.35 (3H, OCH3),
3.51-3.55 (2H, CH2O), 4.25-4.30 (2H, NCH2), 7.79-7.88
(2H, 6¢-H, 6-H), 8.28 (1H, 2-H), 8.31-8.34 (1H, 5¢-H),
8.66-8.7 (2H, 3¢-H, 5-H), 9.02 (1H, 7-H), 16.78 (1H, OH);
13C NMR (CDCl3): d (ppm) 22.7, 25.3, 38.5, 42.2, 63.1,
74.6, 93.2, 120.8, 127.4 (2C), 128.4, 129.7 (2C), 131.5,
137.9, 138.4, 142.2, 151.7, 154.6, 162.5, 168.1, 177.4;
Yield = 64%, m.p = 202 °C, Mass: 516 m/z.
(iii) Dye 3
Diazotization of 6-chloro-4-fluorosulfonyl-2-nitro-
aniline was carried out with nitrosylsulphuric acid. For this
purpose, 6-chloro-4-flourosulfonyl-2-nitroaniline (10 mmol,
0.254 g) was dissolved in the solution of acetic acid and
propionic acid (4:1, 50 mL) and then it was added to the so-
lution of sodium nitrite (10 mmol, 0.07 g) and sulfuric acid
(15 mL) at a temperature of 5-10 °C. The reaction mixture
was stirred at this temperature for 3 hours. The obtained
clear diazonium salt solution was used immediately in the
coupling reaction. The pH of the diazonium salt solution
was adjusted to 5-6 by adding sodium acetate solution. The
diazotized 6-chloro-4-fluorosulfonyl-2-nitroaniline was
added to a solution containing 10 mmol (0.285 g) of cou-
pling component (4-hydroxy-N-3-methoxypropyl-1,8-naph-
thalimide) in 20 mL of methoxyethanol. After 13 hours the
reaction was completed and the precipitated dye was fil-
2.3. Instrumentation
The purified dyes and their corresponding intermedi-
ates were characterized by the following instruments:
1. FTIR measurements were carried out on a Bomene,
Canada instrument (by the KBr method).
2. 1H NMR and 13C NMR measurements were carried
out on a 300 MHz brucker instrument.
3. DSC thermal analyses were carried out on a Du-
pont 2000 DSC instrument.
4. UV-visible spectrophotometry was carried out on a

Alkali-clearable Azonaphthalimide Disperse Dyes
J. Chin. Chem. Soc., Vol. 56, No. 5, 2009 1039
Cecil double beam transmission spectrophotometer. The
lmax, emax and solvatochromic effects were also determined.
5. Mass spectroscopy was carried out on an Agilent
technology (hp), model 5973, Ion Source: electron impact
70 ev.
pared nitrosylsulphuric acid at below 10 °C until the
diazonium salt was formed (note: at higher temperatures
the diazonium salt of the series will decompose and nitro-
gen gas will be evolved).11 However, basic strength of the
amine will be reduced; due to the presence of nitro and
chloro group in the aromatic amine derivatives, therefore,
the reaction needs stronger NO+HSO4- group.
2.4. Application and dyeing properties
Polyester fabric (1 g) was pretreated with a nonionic
detergent, (5 g/1) at 80 °C for 20 min prior to being used for
dyeing. The samples were dyed in a rotadyer apparatus
(Nasaj sanat yazd) using acetic acid (pH = 4-5) and L.G =
50:1. The build up properties of the synthesized dyes on
polyester fabrics obtained by dyeing with dye dispersions
were 0.1, 0.3, 0.5, 0.7, 1, 1.5, 2 and 4% (omf). Dyeing was
carried out by raising the dye bath temperature from 30 °C
to 90 °C at 2 °C/min, followed by 90 °C to 130 °C at 1
°C/min and keeping it at this temperature for 60 min and
cooling to 70 °C at 3 °C/min.
3.2. Synthesis of the coupling component (4-hydroxy-
N-3-methoxypropyl-1,8-naphthalimide)
Preparation of the coupling component was carried
out by utilizing acenaphthene as a starting material and
then subsequent processes such as sulfonation, oxidation,
imidation and hydroxylation were carried out.10 The yield,
1
melting point, FTIR and H NMR of the 4-hydroxy-N-3-
methoxypropyl-1,8-naphthalimide is given in previous
part.
Some of the dyed samples were reduction cleared us-
ing the solution of sodium hydrosulfite (2 g/1), sodium hy-
droxide (1 g/1) and detergent (1 g/1). Other samples were
alkali cleared by utilizing sodium carbonate (20 g/l) and
detergent (1 g/1) at liquor to goods ratio of 50:1 (Fig. 2).
The light fastness, wash fastness, rubbing and subli-
mation fastness of each dye was determined according to
ISO 105/B, ISO 105/C, ISO 105-X12 and ISO 105 P01
standards, respectively.
Solution of the coupling component namely 4-hy-
droxy-N-3-methoxypropyl-1,8-naphthalimide was pre-
pared to which the diazonium salts were added gradually in
acidic medium to yield different dyes (1-4). It is noteable
that dye 4 is made from diazotized p-nitroaniline coupled
with the 4-hydroxy-N-3-methoxypropyl-1,8-naphthalimide
as a comparison sample. The yield percentage, DSC, FTIR,
1H NMR, 13C NMR and Mass spectra of synthesized dyes
are given in previous part.
3. RESULTS AND DISCUSSION
3.3. Spectral Characteristics of the dyes
A colour-structure relationship plays a remarkably
dominant role in producing the desirable dyes. In view of
the commercial importance of producing dyes the relation-
ship between colour and molecular structure is very impor-
tant. Due to this matter dye manufacturers have a consider-
able interest in producing azo dyes.12,13 In this respect, the
wavelength of maximum absorption (lmax), extinction co-
efficient (emax) and half-band width (Dn1/2) of dyes are all
important. The lmax of the visible band indicates the hue of
the dyes and the quantity of the intensity of the visible band
is of economic importance as it is a measure of the strength
of the dye. The emax should be above ca. 20,000 1 mol-1cm-1
for acceptable commercial purposes.1
3.1. Synthesis of the diazo components
Preparations of the diazo components were carried
out by the use of N-acetyl sulfanilyl chloride and then sub-
sequent reactions such as fluorination, hydrolysis, nitration
and chlorination were carried out respectively.5 The yields,
1
melting points, FTIR and H NMR spectra of the diazo
components and coupling component are given in previous
part.
The diazotization of 4-fluorosulfonylaniline was car-
ried out with the hydrochloric acid and sodium nitrite, but
the diazotization of its nitro and chloro derivatives were
carried out with the aid of nitrosylsulphuric acid. The dis-
solution of sodium nitrite in concentrated sulphuric acid
followed by slow addition of the given amine to the pre-
A series of dyes having different substituents were
synthesized and the wavelength of maximum absorption
and emax of the dyes were measured in the chloroform solu-
tion. The dyes had hues from red to red-orange as given in
Table 1.
Fig. 2. Profile of reduction and alkali-clearing.
All the synthesized dyes (1-4) have two lmax between

1040 J. Chin. Chem. Soc., Vol. 56, No. 5, 2009
Parvizi et al.
mentioned dyes 1, 2, 3 and 4 have nearly the same lmax
given in Table 1.
Table 1. The lmax and the emax of the synthesized dyes in CHCl3
Dye Chloroform lmax (nm)
Dn1/2 (nm)
ºmax (1 mol-1cm-1)
35480
The hydroxyl group in the coupling component ring
gives intramolecular hydrogen bond with the nitrogen in
the b-position leading to the brightness in all synthesized
dyes (Table 1).
1
2
3
4
505.7
359.6
507.5
374.0
501.8
365.9
513.6
364.2
091
100
117
104
37217
31038
36928
Analogously substituted 4-aminoazobenzenes, e.g.
structure I which (R = SO2F), having lmax at 469 nm9 is still
36.7 nm, 38.5 nm, 32.8 nm and 44.6 nm more hypso-
chcromic compared with dyes 1-4, respectively. Therefore,
the effect of the naphthyl residue and the carbonyl groups
are apparent and the dyes 1-4 are bathochromic with re-
spect to the analogous aminoazobenzenes I.
300-700 nm. In the UV range, there are only naphthalene
bands, characteristic for simple naphthalene derivatives
which are ascribed to the absorption of the benzeneazo-
naphthalene (BAN) chromophore and in the visible range
bands characteristic for azo dyes.14-17 The chromophore in
the 340-375 nm range and in the visible range the K-band
(p®p* shifts) appears in the region 500-589 nm, charac-
teristic for azo dyes.18 The present considerations are lim-
ited to a discussion of bands within 206-589 nm, where the
known K and R bands (n®p* shifts) appear and show char-
acteristic changes depending on the solvent used.19
Structure I
C2H5
O
N=N
N
O
R
C2H5
3.4. Investigation of the solvatochromic effects
The spectrophotometric properties of the prepared al-
kali-clearable disperse dyes in various solvents were exam-
ined.
Introduction of the phenylazo chromophore into the
3-position of 1,8-naphthalimides results in a large batho-
chromic shift in the absorption maxima in chloroform (Ta-
ble 1) compared with the usual yellow colour of 4-nitro-N-
substituted-1,8-naphthalimides and the usual orange col-
our of 4-amino-N-substituted-1,8-naphthalimides.15,16
The visible absorption maxima of several donor-sub-
stituted azobenzenes were considered20 and it is clear that
for a monosubstituted dye the bathochromic shift depends
on the expected manner of the electron donating strength of
the substituent. Since the electronic transition in these com-
pounds involves a general migration of electron density
from the donor group towards the azo group, it is not sur-
prising that electron withdrawing groups in the diazonium
component ring exert a bathochromic effect and electron
donating groups in the coupling component ring exert a
bathochromic effect.20 It is found that the bathochromic
shift in these series of disperse dyes is related roughly to the
Hammett s-constant for the electron withdrawing group.20
Similar investigations have been carried out on naphtha-
limides series of disperse dyes.15,16,21
The lmax shifts of the prepared dyes in various sol-
vents are brought about by the salvatochromic effect result-
ing from changes in the dielectric constant of the solvent
(p®p* transition) (Table 2).2
Solvent-solute interactions can have various influ-
ences on an absorption spectrum. Thus the position and in-
tensity of a band may vary, as may the band width. In many
dyes, however, the ground state is less polar than the ex-
cited state, thus a polar solvent will tend to stabilize the ex-
cited state more than the ground state, giving rise to a
bathochromic shift.20
Solvatochromic effects of the synthesized dyes in dif-
ferent solvents such as toluene, DMF and chloroform were
measured. The results indicated that the lmax in the toluene
solvent is 4-6 nm more than chloroform solvent (Table 2).
A considerable change was observed in changing the
polarity of the solvents from toluene to DMF; these changes
are 58.8 nm, 96 nm, 79.2 nm and 73 nm for the dyes 1-4 re-
spectively. The most change is ascribed to the dye 2 and the
least change is ascribed to the dye 1 (Table 2). These obser-
vations are in accord to the other results.15,16,21-25 In all
cases, positive solvatochromic effect is observed from the
changing solvent polarity.
In the present study as illustrated in Fig. 1, the naph-
thalimide residue acts as a coupling component, due to hav-
ing two withdrawing carbonyl groups which are weak do-
nor groups and following the same lines of reasoning, the

Alkali-clearable Azonaphthalimide Disperse Dyes
J. Chin. Chem. Soc., Vol. 56, No. 5, 2009 1041
Table 2. The lmax of the synthesized dyes in the different
Table 3. Fastness properties of the synthesized dyes
solvents
Wash fastnessa
S.F
Dye
Chloroform (nm)
DMF (nm)
Toluene (nm)
Dye
L.F
Alkali-
Reduction-
clearing
(180 °C)
None
1
2
3
4
505.7
507.5
501.8
513.6
569.9
607.4
586.7
588.5
511.1
511.4
507.5
515.5
clearing
1
2
3
4
3
3-4
4
5
5
6
4
5
5
5
5
4-5
4-5
2-3
4-5
4-5
5
3-4
7
2
a Staining on cotton, L.F: Light fastness, S.F: Sublimation
fastness
3.5. Investigation of the dyeing of polyester fabric
The prepared dyes were subsequently dyed on poly-
ester fabrics and finally their optical and dyeing properties,
light fastness, wash fastness and sublimation fastness were
determined. The synthesized dyes were applied to polyes-
ter fabric by the high temperature dyeing method. The re-
sults showed that the dyeings were red-yellow to red-blue
and the colour of naphthalimide dyes depends on the delo-
calization of electrons through the conjugated azo chromo-
phore. The leveling properties of the dyes were very good.
The fastness properties on the polyester fabric showed that
the dyes 1 and 4 have very good light fastness, and the dyes
2 and 3 have moderate light fastness (Table 3). The subli-
mation fastness of all dyes was excellent. The naphtha-
limide derivatives show exceptionally excellent thermal
stability and their dyeings have good fastness proper-
ties.15,16,23,24 These dyes tended to undergo association in
the crystalline state which was confirmed by their IR spec-
tra and high melting points.23 This propensity for associa-
tion provides dyes with good thermal stability as reflected
in the sublimation fastness of the dyes. The light fastness,
wash fastness and sublimation fastness of all dyes are
shown in Table 3.
wash fastness will increase, and the reduction-cleared can
be replaced by the alkali-cleared.
4. CONCLUSION
A novel series of naphthalimide-based alkali-clear-
able azo disperse dyes containing a fluorosulfonyl group
has been prepared by using 4-fluorosulfonylaniline, 4-fluo-
rosulfonyl-2-nitroaniline and 6-chloro-4-fluorosulfonyl-
2-nitroaniline as the diazo components and 4-hydroxy-N-
3-methoxypropyl-1,8-naphthalimide constituted the cou-
pling component. The diazo components were synthesized
from N-acetylsulfanilyl chloride, and then subsequent pro-
cesses such as fluorination, hydrolysis, nitration and chlo-
rination were carried out. The coupling component was
prepared from acenaphthene as a starting material and then
subsequent reaction such as sulfonation, oxidation, imida-
tion and hydroxylation were carried out. Diazotization and
coupling reactions were carried out in order to obtain the fi-
nal dyes. Maximal yields were sought after and the reaction
conditions were varied accordingly.
The final dyes were recrystallised in order to be at-
tained in a purified form. The obtained dyes and their corre-
sponding intermediates were characterized by the use of
Wash fastness evaluation of the dyeings on polyester
fabrics showed that uncleared samples possess relatively
low wash fastness. In comparison to the uncleared samples
both alkali-cleared and reduction-cleared samples have an
increase in wash fastness (except dye 4). This case indi-
cates that the dyes containing of fluorosulfonyl group is
converted to a water soluble sulfonate group by alkali-hy-
drolysis (Fig. 3) and can be easily washed-off. Thus, the
1
DSC, FTIR, H NMR, 13C NMR, UV-visible and Mass
spectroscopic techniques.
Spectrophotometric investigations of the prepared
dyes in different solvents were carried out in order to obtain
their absorption maxima, intensities and solvatochromic
O
-
OH
O
R
R
N=N
N
F
S
N=N
N
S
HO
R
R
O
O
Fig. 3. The reaction mechanism of hydrolysis of dyes in alkali medium.

1042 J. Chin. Chem. Soc., Vol. 56, No. 5, 2009
Parvizi et al.
8. Leadbetter, P. W.; Leaver, A. T. Rev. Prog. Color. 1989, 19,
33-39.
effects. The dyes were finally dyed on polyester fabrics in
order to investigate their dyeing properties and the obtain-
able colour gamut.
9. Koh, J.; Greaves, A. J.; Kim, J. P. Dyes Pigm. 2003, 56,
69-81.
The aim of preparing azo disperse alkali-cleared dyes
incorporating fluorosulfonyl group was to convert them
under relatively mild alkaline conditions and temperature
to the dyes containing a water-soluble sulfonate group
without breaking the azo bond.
10. Peters, A. T. J. Soc. Dyers Color. 1990, 106, 275-280.
11. Anne, F. M.; Whitesell, J. K. Core Organic Chemistry; Jones
and Bartlett Inc: Boston, 1997; p 554.
12. Christie, R. M. Colour Chemistry; RSC Publication: Cam-
bridge, 2001; p 45.
13. Zollinger, H. Color Chemistry; Wiley-VCH: Zuirich, 2003;
pp 165-166.
The use of fluorosulfonyl group in these types of dis-
perse dyes shows a desirable build up, excellent wash fast-
ness and offers the selection of alkali clearance to obtain
high wash fastness, displacing reductive clearing and elim-
ination sodium hydrosufite, which has a very high BOD on
conventional disperse dyeing wastewater and generates ar-
omatic amines.
14. Peters, A. T.; Mak, K. H. J. Soc. Dyers Color. 1985, 101,
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Received October 16, 2008.
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