New azodisperse dyes with thiazole, thiophene, pyridone and pyrazolone moiety for dyeing polyester fabrics

Article abstract of DOI:10.1016/j.dyepig.2011.07.009

New antipyrinylazo dyes were prepared by diazocoupling of 4-antipyrinyl diazonium chloride with a variety of coupling components e.g. thiazole, thiophene, pyridone, and pyrazole moieties. The synthesized dyes were characterized by UV-visible absorption, I

Full text of DOI:10.1016/j.dyepig.2011.07.009

Dyes and Pigments 92 (2012) 902e908
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Dyes and Pigments
journal homepage: www.elsevier.com/locate/dyepig
New azodisperse dyes with thiazole, thiophene, pyridone and pyrazolone
moiety for dyeing polyester fabrics
*
M.A. Metwally , Ebrahim Abdel-Galil, Amira Metwally, Fathy A. Amer
Department of Chemistry, Faculty of Science, Mansoura University, 35516 Mansours, Egypt
a r t i c l e i n f o
a b s t r a c t
Article history:
New antipyrinylazo dyes were prepared by diazocoupling of 4-antipyrinyl diazonium chloride with
a variety of coupling components e.g. thiazole, thiophene, pyridone, and pyrazole moieties. The
synthesized dyes were characterized by UVevisible absorption, IR, 1H NMR, and MS spectroscopy. These
dyes were applied as disperse dyes for dyeing polyester fabrics and their fastness properties were
evaluated. Also the position of color in CIELAB coordinates (L*, a*, b*, H*, C*) was assessed.
Ó 2011 Elsevier Ltd. All rights reserved.
Received 26 March 2011
Received in revised form
13 July 2011
Accepted 16 July 2011
Available online 30 July 2011
Keywords:
Azodisperse dyes
Thiazole
Thiophene
Pyridone
Pyrazolone
Polyester fabrics
1. Introduction
2. Experimental
Disperse dyes are very popular and important class of dyes for
dyeing polyester fabrics owing to their brilliancy, wide range of hue,
excellent fastness properties, in addition to the environmental and
economic reasons [1]. Especially useful in this respect are azo dyes
derived from coupling of diazonium salts with sulfur and/or nitrogen
heterocyclic compounds as coupling components. These sulfur
and/or nitrogen heterocyclic azo dyes provide bright strong shades
that range from yellow, orange, red, and blue to green colors [2e5].
Moreover, the aminopyrazole compounds are very useful as
precursors for the synthesis of fused heterocyclic ring systems,
which play an important role in biological and pharmacological
activities [6,7], and they can also be used as intermediates in the
dyestuff industry [8,9].
In view of these findings, and in continuation of our previous
studies [10e13] on the synthesis of a variety of thiazole and thio-
phene derivatives from the readily obtainable cheapest starting
materials for dyeing of polyester fabrics, we now report on the
successful synthesis of several new 5-antipyrinylazo-thiazoles,
4-antipyrinylazo-thiophenes, 5-antipyrinylazo-pridindiones, and
4-antipyrinylazo-pyrazoles and their applications as disperse dyes
for dyeing polyester fabrics.
General: All melting points (uncorrected) are in degree centi-
grade and were determined on Gallenkamp electric melting point
apparatus. Elemental analyses were carried out in the microanalyt-
ical unit, Faculty of Science, University of Mansoura. UV/Vis spectra
were recorded with a Perkin-Elmer Lambda 551 S spectrometer. IR
spectra were recorded (KBr) with on a Mattson 5000 FTIR spec-
1
trometer. H NMR spectra were measured on a Bruker WP 300 in
CDCl3, DMSO-d6 or CF3COOD as solvent, using TMS as an internal
standard. Mass spectra were recorded on a Finnigan MAT 212
instrument. Polyester fabric was used to assess the dyeing behavior
of the compounds under investigation. It was produced by Kafr El-
Dawar Spinning and Weaving Company (Egypt). All applications
and fastness properties of the dyes were studied in Laboratories and
Research sector in Misr Beida Dyers Company, Alexandria, Egypt. The
color parameters of the dyed fibers were determined on a Gre-
tagMacbeth CE 7000a spectrophotometer in Laboratories and
Research sector in Misr Beida Dyers Company, Alexandria, Egypt.
2.1. Synthesis
2.1.1. Synthesis of N-(5-antipyrinylazo-4-methyl-thiazol-2-yl)-
N0-(1-aryl-ethylidene)-hydrazine dyes 4
To a cold solution (0e5 ꢀC) of the thiazole derivatives 3
(0.005 mol) in pyridine (30 ml), a cold solution of freshly prepared
* Corresponding author. Tel.: þ20 101645979.
E-mail address: mamegs@mans.edu.eg (M.A. Metwally).
0143-7208/$ e see front matter Ó 2011 Elsevier Ltd. All rights reserved.
doi:10.1016/j.dyepig.2011.07.009

M.A. Metwally et al. / Dyes and Pigments 92 (2012) 902e908
903
antipyrinyl diazonium chloride (0.005 mol) was added with
2.1.3.4. 5-Anilino-4-antipyrinylazo-2-cyano-3-hydroxythiophene
continuous stirring. The reaction mixture was allowed to stand in
cold for 2 h, diluted with water and then filtered. The
antipyrinylazo-thiazole dyes 4 thus obtained, were dried and
recrystallized from ethanol.
(8d). m.p. ¼158e160 ꢀC. Yield ¼ 87%. IR (
n
/cmꢁ1): 3230, 3174 (NH
and OH), 2179 (CN), 1652 cmꢁ1 (CO). MS (Mþ; EI): m/z (%) ¼ 430
(100). Found: C, 61.20; H, 4.32; N, 19.60%. C22H18N6O2S (430.48)
requires C, 61.38; H, 4.21; N, 19.52%.
2.1.1.1. N-(5-Antipyrinylazo-4-methylthiazol-2-yl)-N0-(1-phenylethy
2.1.4. Synthesis of 2-antipyrinylhydrazono-thioacetoacetanilide
(10)
lidene)-hydrazine (4a). m.p. ¼160e162 ꢀC. Yield ¼ 67%. IR (
n
/cmꢁ1):
3143 (NH), 1653 cmꢁ1 (CO). MS (Mþ; EI): m/z (%) ¼ 445 (74). Found:
C, 61.78; H, 5.12; N, 22.09%. C23H23N7OS (445.54) requires C, 62.00;
H, 5.20; N, 22.01%.
The freshly prepared antipyrinyl diazonium chloride (0.01 mol)
was added with continuous stirring to a cold (0e5 ꢀC) solution of
the thiocarbamoyl derivative 9 (0.01 mol) in ethanol (50.0 ml) and
sodium acetate (4.0 g). The reaction mixture was allowed to stir at
(0e5 ꢀC) for 2 h, and then the solid was collected by filtration. The
obtained precipitate was dried and recrystallized from ethanol.
2.1.1.2. N-(Cyclohexylidene-N0-(5-antipyrinylazo-4-methylthiazol-2-
yl)-hydrazine (4b). m.p. ¼145e145 ꢀC. Yield ¼ 65%. IR (
n
/cmꢁ1):
3135 (NH), 1664 cmꢁ1 (CO). Found: C, 59.77; H, 5.82; N, 23.08%.
C21H25N7OS (423.53) requires C, 59.55; H, 5.95; N, 23.15%.
m.p. ¼ 200e202 ꢀC. Yield ¼ 89%. IR
(
n
/cmꢁ1): 3254 (NH),
/ppm ¼ 2.15 (s, 3H, CH3), 2.60
1653 cmꢁ1 (2 CO). 1H NMR (CDCl3):
d
(s, 3H, CH3), 3.15 (s, 3H, CH3), 7.20e7.60 (m, 5H, Ar-H), 12.25 (s, H,
NH), 14.65 (s, 1H, ¼ NeNH). Found: C, 61.96; H, 5.16; N, 17.23%.
C21H21N5O2S (407.49) requires C, 61.90; H, 5.19; N, 17.19%.
2.1.2. Synthesis of ethyl 2-antipyrinylhydrazono-2-
phenylthiocarbamoyl acetate (6)
The freshly prepared antipyrinyl diazonium chloride (0.01
mol) was added with continuous stirring to a cold (0e5 ꢀC)
solution of the thiocarbamoyl derivative 7 (0.01 mol) in ethanol
(50.0 ml) and sodium acetate (4.0 g). The reaction mixture was
allowed to stir at (0e5 ꢀC) for 2 h, and then the solid was
collected by filtration. The obtained precipitate was dried and
recrystallized from ethanol.
2.1.5. Synthesis of 5-anilino-4-antipyrinylazo-3-hydroxythiophene
dyes 12aed
To a solution of 10 (0.005 mol) in ethanolic sodium ethoxide
(prepared by dissolving 0.12 g sodium metal in 30 ml absolute
ethanol), the appropriate a-halogenated reagent e.g. chloroacetone,
phenacyl chloride, ethyl chloroacetate or chloroacetonitrile
(0.005 mol) was added. The reaction mixture was heated under
reflux for 2 h. The reaction mixture was poured into cold water,
neutralized with dilute HCl, and the solid product that formed was
filtered off and recrystallized from ethanol to afford the corre-
sponding thiophene dyes 12aed.
m.p. ¼165e166 ꢀC, lit. m.p. ¼165 [15]. Yield ¼ 84%. IR (
n
/cmꢁ1):
3274 (NH), 1668 cmꢁ1 (CO). 1H NMR (CDCl3):
d/ppm ¼ 1.38 (t, 3H,
CH3), 2.60 (s, 3H, CH3), 3.08 (s, 3H, CH3), 4.30 (q, 2H, CH2), 7.25e7.62
(m, 5H, Ar-H), 12.70 (s, H, NH), 15.87 (s, 1H, ¼ NeNH). Found: C,
60.25; H, 5.36; N, 16.08%. C22H23N5O3S (437.51) requires C, 60.39; H,
5.30; N, 16.01%.
2.1.5.1. 2-Acetyl-5-anilino-4-antipyrinylazo-3-methylthiophene (12a).
2.1.3. Synthesis of 5-anilino-4-antipyrinylazo-3-hydroxythiophene
dyes 8aed
To a solution of 6 (0.005 mol) in ethanolic sodium ethoxide
(prepared by dissolving 0.12 g sodium metal in 30 ml absolute
m.p. ¼ 272e273 ꢀC. Yield ¼ 84%. IR (
n
/cmꢁ1): 3254 (NH), 1664 cmꢁ1
(2 CO). Found: C, 64.64; H, 5.28; N, 15.80%. C24H23N5O2S (445.54)
requires C, 64.70; H, 5.20; N, 15.72%.
ethanol), the appropriate
a
-halogenated reagent e.g. chloroacetone,
2.1.5.2. 5-Anilino-4-antipyrinylazo-2-benzoyl-3-methylthiophene
phenacyl chloride, ethyl chloroacetate or chloroacetonitrile
(0.005 mol) was added. The reaction mixture was heated under
reflux for 2 h. The reaction mixture was poured into cold water,
neutralized with dilute HCl, and the solid product that formed was
filtered off and recrystallized from ethanol or DMF-ethanol (1:2)
mixture to afford the corresponding thiophene dyes 8aed.
(12b). m.p. ¼ 255e256 ꢀC. Yield ¼ 88%. IR (
n
/cmꢁ1): 3272 (NH),
1664 cmꢁ1 (2 CO). 1H NMR (CDCl3):
d
/ppm ¼ 2.50 (s, 3H, CH3), 2.68
(s, 3H, CH3), 3.28 (s, 3H, CH3), 7.02e7.77 (m, 15H, Ar-H), 13.50 (s, H,
NH). Found: C, 68.74; H, 4.89; N, 13.86%. C29H25N5O2S (507.61)
requires C, 68.62; H, 4.96; N, 13.80%.
2.1.5.3. 5-Anilino-4-antipyrinylazo-2-ethoxycarbonyl-3-methylthio
2.1.3.1. 2-Acetyl-5-anilino-4-antipyrinylazo-3-hydroxythiophene
phene (12c). m.p. ¼ 226e227 ꢀC. Yield ¼ 76%. IR (
n
/cmꢁ1): 3278
(8a). m.p. ¼ 234e235 ꢀC. Yield ¼ 83%. IR (
n
/cmꢁ1): 3221, 3142 (NH
(NH), 1691 (CO), 1665 cmꢁ1 (CO). 1H NMR (CDCl3):
d/ppm ¼ 1.35
and OH), 1635 (CO), 1594 cmꢁ1 (CO). Found: C, 61.82; H, 4.79; N,
15.58%. C23H21N5O3S (447.51) requires C, 61.73; H, 4.73; N, 15.65%.
(t, 3H, CH3), 2.70 (s, 6H, 2CH3), 3.26 (s, 3H, CH3), 4.35 (q, 2H, CH2),
7.06e7.56 (m, 10H, Ar-H),13.49 (s,1H, NH). Found: C, 63.29; H, 5.38;
N, 14.81%. C25H25N5O3S (475.56) requires C, 63.14; H, 5.30; N,
14.73%.
2.1.3.2. 5-Anilino-4-antipyrinylazo-2-benzoyl-3-hydroxythiophene
(8b). m.p. ¼ 237e239 ꢀC. Yield ¼ 80%. IR (
n
/cmꢁ1): 3258, 3138 (NH
and OH), 1662 (CO), 1589 cmꢁ1 (CO). 1H NMR (CDCl3):
d
/ppm ¼ 2.78
2.1.5.4. 5-Anilino-4-antipyrinylazo-2-cyano-3-methylthiophene (12d).
(s, 3H, CH3), 3.32 (s, 3H, CH3), 7.13e7.84 (m, 15H, Ar-H), 13.25 (s, H,
NH), 15.22 (s, 1H, OH). Found: C, 65.84; H, 4.69; N, 13.82%.
C28H23N5O3S (509.58) requires C, 66.00; H, 4.55; N, 13.74%.
m.p. ¼ 269e270 ꢀC. Yield ¼ 81%. IR (
n
/cmꢁ1): 3248 (NH), 2196 (CN),
1653 cmꢁ1 (CO). MS (Mþ; EI): m/z (%) ¼ 428 (82). Found: C, 64.38;
H, 4.72; N, 19.68%. C23H20N6OS (428.51) requires C, 64.47; H, 4.70;
N, 19.61%.
2.1.3.3. 5-Anilino-4-antipyrinylazo-2-ethoxycarbonyl-3-hydroxythio
phene (8c). m.p. ¼130e132 ꢀC. Yield ¼ 78%. IR (
n
/cmꢁ1): 3266, 3152
2.1.6. Synthesis of 5-antipyrinylazo-3-cyano-4-methylpyridin-2,6-
dione (14)
(NH and OH), 1655 (CO), 1591 cmꢁ1 (CO). 1H NMR (CDCl3):
d
/ppm ¼ 1.35 (t, 3H, CH3), 2.72 (s, 3H, CH3), 3.32 (s, 3H, CH3), 4.32 (q,
A mixture of ethyl 2-antipyrinylhydrazono-acetoacetate (13)
(0.01 mol), cyanoacetamide (0.01 mol), and potassium carbonate
(1.38 g) in acetone (50 ml) was stirred and refluxed until the
reaction was completed (about 3e4 hours). The reaction mixture
2H, CH2), 7.08e7.52 (m, 10H, Ar-H), 11.21 (s, H, OH), 13.65 (s, 1H,
NH). Found: C, 60.49; H, 4.89; N, 14.76%. C24H23N5O4S (477.54)
requires C, 60.36; H, 4.85; N, 14.67%.

904
M.A. Metwally et al. / Dyes and Pigments 92 (2012) 902e908
was poured into ice-water and the crude product was filtered, dried
and recrystallized from ethanol to give 14 as red crystals.
60 min and rapidly cooling to 50 ꢀC. The dyed fibers was rinsed
with cold water and reduction cleared (1 g dmꢁ3 sodium hydroxide,
1 g dmꢁ3 sodium hydrosulfite, 10 min, 80 ꢀC). The samples were
rinsed with hot and cold water and finally air-dried.
m.p. > 300 ꢀC. Yield ¼ 92%. IR (
n
/cmꢁ1): 3424 (NH), 3112 (OH),
2198 (CN), 1627 cmꢁ1 (broad, CO). 1H NMR (DMSO):
d
/ppm ¼ 2.40
(s, 3H, CH3), 2.60 (s, 3H, CH3), 3.25 (s, 3H, CH3), 7.20e7.55 (m, 5H,
Ar-H), 7.95 (s, 1H, NH), 10.70 (s, 1H, OH). Found: C, 59.28; H, 4.46; N,
23.13%. C18H16N6O3 (364.36) requires C, 59.34; H, 4.43; N, 23.07%.
2.2.2. Color fastness tests
Fastness to washing, perspiration, rubbing, sublimation, and
light was tested according to the reported methods [14].
2.1.7. 4-Antipyrinylazo-3-methyl-5-hydroxypyrazole-1-carbothioic
acid amide (15)
2.3. Color assessment
A mixture of ethyl 2-antipyrinylhydrazono-acetoacetate (13)
(0.01 mol), thiosemicarbazide (0.01 mol), and sodium acetate
(1.00 g) in ethanol (50 ml) was refluxed for 4 h. During the reaction,
the red product precipitated. The crude product was filtered,
washed with water, dried and recrystallized from ethanol to afford
the antipyrinylazo-pyrazole 15 as red crystals.
The colorimetric parameters (Table 2) of the dyed polyester
fabrics were determined on a reflectance spectrophotometer
(Gretag-Macbeth CE 7000a), equipped with a D65/10ꢀ source and
barium sulphate as standard blank, UV excluded, specular
component included and three repeated measurements average
settings.
m.p. ¼ 228e230 ꢀC. Yield ¼ 88%. IR (
n
/cmꢁ1): 3340, 3192, 3162
/ppm ¼ 2.50
(NH2 and OH), 1659 cmꢁ1 (CO). 1H NMR (DMSO):
d
(s, 3H, CH3), 2.60 (s, 3H, CH3), 3.25 (s, 3H, CH3), 7.20e7.55 (m, 5H,
Ar-H), 7.85 (s, 2H, NH2), 13.20 (s, 1H, OH). Found: C, 51.80; H, 4.68;
N, 26.35%. C16H17N7O2S (371.42) requires C, 51.74; H, 4.61; N,
26.40%.
3. Results and discussion
3.1. Discussion of the synthetic strategy
Condensation of bromoacetone (1) with thiosemicarbazone
derivatives 2 by reflux in ethanol containing a catalytic amount of
sodium acetate afforded the corresponding 4-substituted-2-
thiazolylhydrazones of ketones 3 [15] (Scheme 1). The thiazole C-
5 position in derivatives 3 is highly reactive toward diazocoupling
with the antipyrinyl diazonium chloride to furnish the corre-
sponding antipyrinylazo-thiazole dyes 4 (Scheme 1). The structure
of the highly functionalized thiazolyl dyes 4 was assigned on the
basis of their elemental analyses and spectral data. The IR spectra of
the dyes 4 clearly indicate the presence of NH absorption band at
3143e3135 cmꢁ1 and CO absorption band at 1664e1653 cmꢁ1. The
mass spectrum of 4a (for example) showed the molecular ion peak
at m/z ¼ 445 (intensity 74%) corresponding to the molecular weight
of the molecular formula C23H23N7OS.
2.1.8. Synthesis of 5-amino-4-antipyrinylazo-1-benzenesulfonyl-
1H-pyrazol-3-ol (18)
The freshly prepared antipyrinyl diazonium chloride
(0.005 mol) was added with continuous stirring to a cold (0e5 ꢀC)
solution of the benzenesulfonyl-2-cyanoacetic acid hydrazide 16
(0.005 mol) in pyridine (50.0 ml). The reaction mixture was
allowed to stir at (0e5 ꢀC) for 2 h, diluted with water, and then the
solid product was collected by filtration. The obtained precipitate
was dried and recrystallized from ethanoleDMF mixture (3:1).
m.p. ¼ 205e206 ꢀC. Yield ¼ 57%. IR (
n
/cmꢁ1): 3461, 3432, 3293
/ppm ¼ 2.60 (s,
(NH2 and OH), 1658 cmꢁ1 (CO). 1H NMR (DMSO):
d
3H, CH3), 3.20 (s, 3H, CH3), 7.20-7.50 (m, 10H, Ar-H), 10.15 (s, 2H,
NH2), 12.35 (s, 1H, OH). MS (Mþ; EI): m/z (%) ¼ 453 (12). Found: C,
52.83; H, 4.28; N, 21.71%. C20H19N7O4S (453.47) requires C, 52.97; H,
4.22; N, 21.62%.
Treatment of ethyl a-phenylthiocarbamoylacetoacetate (5) [16]
with the antipyrinyl diazonium chloride in ethanol containing
sodium acetate effected acetyl group cleavage (JappeKlingmann
reaction) with the formation of the corresponding thiocarbamoyl
intermediate 6. The versatile ethyl 2-antipyrinylhydrazono-
2-phenylthiocarbamoyl acetate derivative 6 underwent hetero-
2.1.9. Synthesis of 5-amino-4-(antipyrinylazo)-3-hydroxy-
pyrazole-1-carbothioic acid phenylamide (21)
The freshly prepared antipyrinyl diazonium chloride
(0.005 mol) was added with continuous stirring to a cold (0e5 ꢀC)
solution of the thiourea derivative 19 (0.005 mol) in pyridine
(50.0 ml). The reaction mixture was allowed to stir at (0e5 ꢀC) for
2 h, diluted with cold water, and then the solid product was
collected by filtration. The obtained precipitate was dried and
recrystallized from ethanoleDMF mixture (5:1).
cyclization with several a-halogenated reagents e.g. chloroacetone,
phenacyl chloride, ethyl chloroacetate and chloroacetonitrile in
the presence of sodium ethoxide to furnish the corresponding
4-antipyrinylazo-3-hydroxy-2-substituted-thiophene dyes 8aed.
The formation of thiophene derivatives 8aed from the reaction
of 6 with the appropriate alkylating agent such as chloroacetone,
m.p. ¼ 274e275 ꢀC. Yield ¼ 63%. IR (
n
/cmꢁ1): 3430, 3295 (NH2
and OH), 1652 cmꢁ1 (CO). MS (Mþ; EI): m/z (%) ¼ 448 (7). Found: C,
56.38; H, 4.54; N, 24.90%. C21H20N8O2S (448.50) requires C, 56.24;
H, 4.49; N, 24.98%.
Me
S
O
R1
EtOH
R1
N
N
Br
+
N
H2N
N
Me
H
N
H
R2
S
R2
1
2
3
2.2. Dyeing procedure and fastness determinations
a: R1 = Me; R2 = Ph
b: R1R2 = C6H10
2.2.1. Dyeing of polyester fabrics
AnN2 Cl
A dispersion of the dye was produced by dissolving the appro-
priate amount of dye (2% shade) in 1 cm3 acetone and then added
dropwise with stirring to the dyebath (liquor ration 20:1) con-
taining 1% Setamol WS (sodium salt of a condensation product of
naphthalene sulfonic acid and formaldehyde) as anionic dispersing
agent of BASF. The pH of the dyebath was adjusted to 5.5 using
aqueous acetic acid and the wetted-out polyester fabrics were
added. Dyeing was performed by raising the dyebath temperature
to 130 ꢀC at a rate of 3 ꢀC/min, holding at this temperature for
Me
O
Me
R1
N
Me
N
N
N
An =
N
N
S
R2
H
Ph
N
An
4
Scheme 1.

M.A. Metwally et al. / Dyes and Pigments 92 (2012) 902e908
905
O
O
S
phenacyl chloride and ethyl chloroacetate seems to follow the
sequence outlined in Scheme 2. It is suggested that the reaction
starts through nucleophilic attack of the thiolate group to form the
nonisolable S-alkylated intermediate 7 which via nucleophilic
substitution and intramolecular cyclocondensation by ethanol
elimination gave the corresponding polyfunctionally 3-hydroxy-
substituted-thiophenes 8aed.
Me
PhHN
Me
Me
9
Me
S
H
An
N N
An
N N
O
O
AnN2 Cl
ClCH2COR
PhHN
SCH2COR
EtOH/NaOAc
PhHN
The structures of the highly functionalized 3-hydroxythiophene
dyes 8aed were elucidated on the basis of their elemental analyses
and spectral data. The IR spectrum of the dye 8a showed absorption
peaks at 3142 and 1594 cmꢁ1 due to the presence of hydroxyl group
and conjugated carbonyl group, respectively. The strong decrease in
the carbonyl and hydroxyl absorption frequencies is attributed to
the intramolecular H-bond structure. The 1H NMR spectrum of 8b
(as an example) showed singlet signals at 2.78 and 3.32 ppm due to
methyl protons and a multiplet signal in the region 7.13e7.84 cor-
responding to the aromatic protons. The presence of a broad singlet
at 13.25 ppm was attributed to the presence of NH group, while the
hydrogen bonded OH group is downfield shifted to 15.22 ppm. The
mass spectrum of 8d (for example) showed the molecular ion peak
at m/z ¼ 430 (intensity 100%) corresponding to the molecular
weight of the molecular formula C22H18N6O2S.
10
11
Me
Me
N
-EtOH
ClCH2CN
Me
An =
N
Ph
O
An
N
N
Me
O
An
N N
PhHN
PhHN
C
N
S
S
R
12d
12a: R = Me
12b: R = Ph
12c: R = OEt
Scheme 3.
Treatment of a-phenylthiocarbamoyl-acetylacetone (9) with the
antipyrinyl diazonium chloride in ethanol containing sodium
acetate effected one acetyl group cleavage (JappeKlingmann reac-
tion) with the formation of the corresponding thiocarbamoyl
intermediate 10. The versatile 2-antipyrinylhydrazono-thio-
The structures of the highly functionalized 3-methylthiophene
dyes 12aed were elucidated on the basis of their elemental anal-
yses and spectral data. The IR spectrum of the dye 12a showed an
absorption peak at 3254 cmꢁ1 corresponding to NH and a broad
absorption peak at 1664 cmꢁ1 corresponding to the carbonyl
groups. The 1H NMR spectrum of 12b (as an example) showed
singlet signals at 2.50, 2.68 and 3.28 ppm due to methyl protons
and a multiplet signal in the region 7.02e7.77 corresponding to the
aromatic protons, in addition to a singlet signal at 13.50 ppm due to
the presence of NH group. The mass spectrum of 12d showed the
molecular ion peak at m/z ¼ 428 (intensity 82%) corresponding to
the molecular weight of the molecular formula C23H20N6OS.
Pyridones and pyrazolones as coupling components have been
shown to be important colorants for yellow to orange dyes in
industrial applications. Moreover, N-substituted pyridone azo
disperse dyes, which were derived from benzenoid derivatives as
coupling components, show good color strength, luminous colors
and excellent light fastness [17e19]. It is further reported that
pyrazolones derivatives as coupling component can be used to
synthesize yellow 4-arylazo pyrazolones dyes [20].
acetoacetanilide (10) underwent heterocyclization with several a-
halogenated reagents e.g. chloroacetone, phenacyl chloride, ethyl
chloroacetate and chloroacetonitrile in ethanol-sodium ethoxide
solution to furnish the corresponding 4-antipyrinylazo-3-methyl-
2-substituted-thiophene dyes 12aed (Scheme 3).
The formation of thiophene derivatives 12aed from the reaction
of 9 with the appropriate alkylating agent such as chloroacetone,
phenacyl chloride, ethyl chloroacetate and chloroacetonitrile seems
to follow the sequence outlined in Scheme 3. It is suggested that the
reaction starts through nucleophilic attack of the thiolate group to
form the nonisolable S-alkylated intermediate 11 which via
nucleophilic addition and intramolecular cyclocondensation by
water elimination gave the corresponding 3-methyl-substituted-
thiophenes 12aed.
O
5-Antipyrinylazo-3-cyano-4-methylpyridin-2,6-dione
(14)
COOEt
Me
(Scheme 4) was synthesized by cyclization of ethyl 2-anti
pyrinylhydrazono-acetoacetate (13) with cyanoacetamide in hot
acetone containing potassium carbonate. The chemical structure of
14 was elucidated on the basis of its elemental and spectroscopic
analysis. The IR spectrum displayed absorption bands at 3424
corresponding to NH, 3112 for the hydroxyl group, 2198 the nitrile
group (CN) and 1627 cmꢁ1 corresponding to the carbonyl groups.
PhHN
S
5
O
C
H
An
N N
An
N
N
COOEt
S
OEt
AnN2 Cl
ClCH2COR
EtOH/NaOAc
PhHN
SCH2COR
PhHN
The 1H NMR spectrum revealed a singlet signal at
methyl protons (pyridone-CH3), a singlet signals at
due the methyl protons (pyrazole-2CH3), a multiplet at
due to aromatic protons, a singlet signal at 7.95 for NH proton and
a singlet signal at 10.70 due to OH proton.
d
2.40 due to
2.60 and 3.25
7.20e7.55
6
7
Me
d
Me
N
N
O
d
-EtOH
ClCH2CN
OH
An =
d
Ph
d
On the other hand, cyclization of 13 with thiosemicarbazide by
heating in ethanol containing sodium acetate afforded the
antipyrinylazo-pyrazolone derivative 15 (Scheme 4). The IR spec-
trum of 15 showed the characteristic absorption bands for the NH2
and OH groups at 3340, 3192, 3162 cmꢁ1 and absorption band at
1659 cmꢁ1 for the carbonyl group. The 1H NMR spectrum revealed
An
N
N
O
H
An
N N
O
R
PhHN
PhHN
C N
S
S
8d
8a: R = Me
8b: R = Ph
8c: R = OEt
singlet signals at
d 2.50, 2.60 and 3.25 for the methyl protons,
Scheme 2.
a multiplet at 7.20e7.55 for the aromatic protons, a singlet at
d

906
M.A. Metwally et al. / Dyes and Pigments 92 (2012) 902e908
O
O
Me
O
AnN2 Cl
H
O
An HN
N
O
Me
OEt
O
NC
HN
N
NHPh
H
AnN2 Cl
pyridine
N
NC
N
NHPh
H
N
H
OEt
N
S
13
S
H2NCSNHNH2
H2NCOCH2CN
19
An
20
S
Me
N
N
NH2
An
N
N
CN
O
Me
Me
An
N
H2N
N
O
NH
An
N
N
OH
Me
OH
Me
N
HO
N
H
Me
An =
N
N
N
N
An =
H2N
N
Ph
N
N
N
O
14
Ph
An
O
NHPh
S
S
NHPh
15
B
A
21
Scheme 4.
Scheme 6.
d
7.85 for the amino protons (NH2), and a singlet at
d 13.20 due to
OH proton.
3.1.1. Conclusion
The azo coupling between antipyrinyl diazonium chloride 1 and
benzenesulfonyl-2-cyanoacetic acid hydrazide 16 did not stop at
the antipyrinylhydrazono intermediate 17 but this cyclized directly
to afford the corresponding 4-antipyrinylazo-1-benzenesulfonyl-
1H-pyrazole 18 (Scheme 5). The pyrazole structure 18 was estab-
lished on the basis of the elemental and spectroscopic data. The IR
spectrum clearly indicates the lack of cyano group absorption and
Several antipyrinylazo dyes were prepared, e.g. thiazole, thio-
phene, pyridone, and pyrazole moieties. The newly synthesized
dyes were applied as disperse dyes for dyeing polyester fabrics and
their fastness properties were evaluated. Also the position of color
in CIELAB coordinates (L*, a*, b*, H*, C*) was assessed.
3.2. Absorption spectral characteristics
showed the amino group absorption at 3461 and 3293 cmꢁ1
Furthermore, the 1H NMR spectrum revealed singlet signals at
2.60 and 3.20 for the methyl protons, a multiplet at 7.20e7.50 for
the aromatic protons, a singlet at 10.15 for the amino protons
(NH2), and a singlet at 12.35 due to OH proton.
.
Generally, variation in color of these dyes results from the
alternation in coupling components. Since the synthesized dyes
obtained varied in color from yellow to reddish violet, a convenient
method of measuring the color of the compound was to study the
absorption spectra of their solutions. The visible absorption maxima
for the synthesized dyes were measured in chloroform and are lis-
ted in Table 2. The absorption maxima of the synthesized dyes
ranged from 415 to 480 nm. Within the series of antipyrinylazo dyes
investigated, the relation between the shift observed in the
absorption maxima, and polar characteristics of the coupling
moieties, may be summarized as follows: (i) The dye 4a (lmax ¼ 454)
substituted with phenylethylidene group absorb maximally at
longer wavelengths than the corresponding dye with cyclo-
d
d
d
d
The azo coupling between antipyrinyl diazonium chloride and
thiourea derivative 19 afforded the corresponding 4-antipyrinylazo-
3-hydroxy-pyrazole-1-carbothioic acid phenylamide 21 through in
situ heterocyclization of the antipyrinyl-hydrazono intermediate 20
(Scheme 6). The chemical structure of 21 was secured by the correct
elemental and spectroscopic data.
The dyes 18 and 21 may exist in two tautomeric forms, namely
the antipyrinylazopyrazolone form A and the antipyrinylazo-
hydroxy-pyrazole form B.
hexylidene group 4b
methylthiophene dyes 12 absorb maximally at longer wavelengths
than the corresponding antipyrinylazo-4-hydroxythiophene dyes 8.
(
lmax ¼ 438). (ii) The antipyrinylazo-3-
O
H
O
NC
HN
N
AnN2 Cl
pyridine
H
3.3. Dyeing and fastness properties
N
SO2Ph
NC
N
H
N
SO2Ph
N
H
The development of disperse dyes “Dyes insoluble in water and
applied from aqueous dispersion rather than from solution” was
a revolutionary solution to the problem of coloration of synthetic
fibers. The dyes were essentially insoluble in water and were
prepared for application by being ground, in the presence of
dispersing agents, to microscopically fine particles of the order of
a few microns and, then, by pan drying the resultant suspension.
The resulting readily dispersible solid could then dye the more
hydrophobic acetate fiber by partitioning into the fiber from low
dye bath concentrations. The synthesized disperse dyes under
investigation 4, 8, 12, 14, 15, 18 and 21) were applied to polyester
fabric at 2% shade by high-temperature pressure technique (130 ꢀC)
and gave generally deep and bright hues, ranging from yellow to
reddish-violet. The dyeings on polyester fabrics were evaluated
in terms of their fastness properties. The dyes gave excellent
16
An
17
Me
An
N
N
O
An
N
N
OH
Me
N
NH
N
An =
H2N
H2N
N
N
N
Ph
O
SO2Ph
SO2Ph
B
A
18
Scheme 5.

M.A. Metwally et al. / Dyes and Pigments 92 (2012) 902e908
907
Table 1
Fastness properties of the synthesized dyes 4, 8, 12, 14, 15, 18 and 21 on polyester fabrics.
Dye
Washing
Perspiration
Acid
Rubbing
Dry
Sublimation fastness
Staining at 180 ꢀC
Light (40 h)
Alkali
Wet
Staining at 210 ꢀ
C
4a
4b
8a
8b
4e5
4
4e5
4
4e5
4
2e3
4
2e3
2e3
2e3
4
2e3
2e3
2e3
3e4
2e3
3
3
4e5
4e5
4e5
4e5
4e5
4e5
4e5
4e5
4
4e5
4e5
4e5
4e5
4e5
3e4
3e4
4e5
4e5
4e5
4e5
4e5
4
2e3
4e5
4e5
4e5
4
2e3
2e3
3e4
4
3e4
4
4
4e5
4
3e4
3
3
2e3
2e3
4e5
3e4
3
2e3
3e4
2e3
2e3
3
3e4
3
3e4
4
4e5
4e5
4e5
4e5
4e5
4e5
4
4e5
4e5
4e5
4e5
4e5
4e5
4e5
4e5
4e5
4e5
4e5
4
4e5
4e5
4e5
4e5
4e5
4e5
4e5
4e5
4e5
4e5
4e5
4
4e5
4
4e5
4e5
4e5
8c
8d
12a
12b
12c
12d
14
15
18
21
4
4e5
4e5
4e5
uniformity of coloration on polyester fabrics and the overall fast-
ness properties of the dyes are shown in Table 1.
3.3.5. Fastness to light
Light fastness of the synthesized dyes on polyester was
moderate (according to the blue scale) and is significantly affected
by the nature of the substituents in the coupling component. In
most cases, the best light fastness (good, 4e5 of the blue wool
standard scale 1e8) was obtained by the antipyrinylazo-thiophene
dyes 8 and 12.
3.3.1. Fastness to washing
The dyed polyester fabrics have very good fastness to washing
according to the international geometric Grey scale. The rather
good fastness properties to washing may be due to the absence of
solubilizing groups, which renders solubility, and wash ability of
the dye-out of the fabrics.
3.4. Color assessment
3.3.2. Fastness to perspiration: (acid and alkaline)
The color parameters of the dyed polyester fabrics were
measured using the GretagMacbeth CE 7000a spectrophotometer.
The assessment of color-dyed fabrics was made in terms of
tristimulus colorimetry. The following CIELAB coordinates are
measured, lightness (L*), chroma (C*), hue angle from 0ꢀ to 360ꢀ (h),
(a*) value represents the degree of redness (positive) and greenness
(negative) and (b*) represents the degree of yellowness (positive)
and blueness (negative).
The measured K/S value given by the reflectance spectrometer
is directly correlated with the dye concentration on the dye
substrate according to the KubelkaeMunk equation: K/S ¼ (1 ꢁ R)2/
2R. Where K ¼ absorbance coefficient, S ¼ scattering coefficient,
R ¼ reflectance ratio.
The results obtained in Table 1; show that the fastness to acid
and alkaline perspiration is rather satisfactory ranging 4e5. Such
results indicate the relative stability of the prepared anti-
pyrinylazothiazole and/or antipyrinylazo-thiophene dyes in acid
and alkaline medium, similar to the conditions used in this test.
3.3.3. Fastness to rubbing
The test is designed to determine the amount of color trans-
ferred from the surface of colored fabrics to another surface by
rubbing. The rubbing fastness test was carried out using the AATCC
crockmeter. Most of the dyes have a moderate (3) to good (4)
rubbing fastness.
The color of the synthesized dyes (4, 8, 12, 14, 15, 18 and 21) on
polyester fabric was evaluated using the CIELAB system in terms of
L*, a* and b*. The color coordinates listed in Table 2 indicate that the
dyes have good affinity to polyester fabric and tend to give the
following conclusions: (i) The dyes under investigation showed
good affinity toward polyester fabric at high temperature (130 ꢀC)
and gave generally deep and bright intense hues, ranging from
yellow to reddish violet. (ii) The color hues of the dyes under
investigation on polyester fabric are shifted to the yellowish
direction on the yellow-blue axis according to the positive values of
b*. (iii) The color hue of the dye 15 on polyester fabric is shifted to
the greenish direction on the redegreen axis as indicated from the
negative value of a* (ꢁ0.20). While the color hues of the other
synthesized dyes on polyester fabrics are shifted to the reddish
direction on the redegreen axis as according to the positive values
of a* for these dyes.
3.3.4. Fastness to sublimation
Sublimation fastness properties of synthesized dyes expressed
as color staining on the undyed polyester piece ranged from good to
very good. In most cases, the best sublimation fastness was
obtained by the antipyrinylazo-thiophene dyes (e.g. dyes 8 and 12).
Table 2
Color coordinates of the dyes 4, 8, 12, 14, 15, 18 and 21 (light source ¼ D65/10ꢀ
observer).
Dye
L*
C*
H*
a*
7.40
b*
K/S
UV lmax
4a
4b
8a
8b
63.90
67.90
57.10
66.90
71.10
65.30
72.20
61.80
61.80
68.20
84.20
87.80
76.00
83.80
16.40
13.70
46.60
58.80
52.30
44.90
37.50
37.70
51.30
34.20
15.30
11.60
17.60
15.50
63.00
71.30
65.30
70.40
68.30
60.80
51.70
49.60
50.60
45.60
57.60
91.00
69.10
82.00
14.60
12.90
42.30
55.30
48.50
39.20
29.40
28.70
39.70
24.40
22.90
21.60
26.50
25.40
0.72
0.45
3.30
2.77
1.70
1.80
0.81
1.39
2.90
1.00
0.71
0.66
0.58
0.68
454
438
468
466
474
470
478
480
480
476
458
444
424
415
4.40
19.40
19.70
19.30
21.90
23.20
24.50
32.50
23.90
8.20
8c
8d
12a
12b
12c
12d
14
15
18
21
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