Disperse dyes based on 5-arylazo-thiazol-2-ylcarbamoyl-thiophenes: Synthesis, antimicrobial activity and their application on polyester

Article abstract of DOI:10.1002/jhet.2153

A series of novel 5-arylazo-thiazol-2-ylcarbamoyl-thiophene derivatives was synthesized, and their chemical structures were secured by elemental and spectroscopic analyses. Their versatility for pharmaceutical purposes and textile dyeing as disperse dyes were reported. The synthesized dyes were applied to polyester fabrics by using high temperature dyeing method at 130°C. The dyed polyester fabrics displayed very good washing and perspiration fastness and moderate light fastness. Finally, the synthesized compounds showed biological activities against Bacillus subtilis, Staphylococcus aureus (Gram positive bacteria), Escherichia coli, and Pseudomonas aeruginosa (Gram-negative bacteria), while no effect had been reported against fungi. The minimum inhibitory concentration of the most active compound was evaluated.

Full text of DOI:10.1002/jhet.2153

Month 2014
Disperse Dyes Based on 5-Arylazo-thiazol-2-ylcarbamoyl-thiophenes:
Synthesis, Antimicrobial Activity and Their Application on Polyester
c
a
M. E. Khalifa,a,b E. Abdel-Latif, and A. A. Gobouri
*
aFaculty of Science, Department of Chemistry, Taif University, Taif 21974, Saudi Arabia
bDepartment of Chemical Engineering, Higher Institute for Engineering and Technology, New Damietta, Egypt
cFaculty of Science, Department of Chemistry, Mansoura University, Mansoura ET 35516, Egypt
*
E-mail: mohamedezzat200@hotmail.com
Received August 16, 2013
DOI 10.1002/jhet.2153
Published online 00 Month 2014 in Wiley Online Library (wileyonlinelibrary.com).
A series of novel 5-arylazo-thiazol-2-ylcarbamoyl-thiophene derivatives was synthesized, and their
chemical structures were secured by elemental and spectroscopic analyses. Their versatility for pharmaceuti-
cal purposes and textile dyeing as disperse dyes were reported. The synthesized dyes were applied to polyester
fabrics by using high temperature dyeing method at 130°C. The dyed polyester fabrics displayed very good
washing and perspiration fastness and moderate light fastness. Finally, the synthesized compounds showed
biological activities against Bacillus subtilis, Staphylococcus aureus (Gram positive bacteria), Escherichia
coli, and Pseudomonas aeruginosa (Gram-negative bacteria), while no effect had been reported against fungi.
The minimum inhibitory concentration of the most active compound was evaluated.
J. Heterocyclic Chem., 00, 00 (2014).
INTRODUCTION
hues, and excellent fastness properties, in addition to
their environmental and economic importance [20–22].
Therefore, we focused on the synthesis of novel thiazolyl-
thiophene moiety as potential monoazo disperse dyes for
dyeing polyester fabrics. In addition, the biological activities
of the synthesized dyes against selected Gram-positive bac-
teria, Gram-negative bacteria, and fungi were also evaluated.
2-Aminothiazoles are mainly known as biologically
active compounds with a broad range of activities and as
intermediates in the synthesis of antibiotics such as the
well known sulfa drugs [1]. A large number of 2-
aminothiazoles have been substituted with different groups
for pharmaceutical purposes [2–5] and are also used in the
syntheses of various types of dyes [6–8].
On the other hand, thiophene nucleus and its derivatives
were proven to constitute the active part of several biolog-
ically active compounds, where the activity of thiophenes
is to treat allergy, asthma, rhinitis, dermatitis, β-cell
lymphomas, tumors, and diseases associated with bacterial,
rhinovirus, or respiratory syncytial virus infections, besides
their antioxidant activity [9–14].
In continuation of our previous studies on the synthesis
of a variety of several new sulfur and/or nitrogen heterocy-
clic azo-disperse dyes from the readily obtainable cheapest
starting materials for dyeing polyester fabrics, which
provide strong shades that range from yellow, orange,
red, and brown colors [15–19]. The polyester fabric has
several advantages over traditional fabrics such as cotton.
It does not absorb moisture but does absorb oil; this quality
makes polyester the perfect fabric for the application of
water-resistant, soil-resistant, and fire-resistant finishes
and stains resistance besides its non-allergenic property,
and disperse dyes are considered to be very popular and
important class of dyes for dyeing polyester fabrics
because of their ease of synthesis, structural variability,
higher chromophoric strength, brilliancy, wide range of
RESULTS AND DISCUSSION
Synthesis and reactions. Coupling of 2-aminothiazole
1 with a variety of aromatic diazonium salts in ethanol
and sodium acetate, yielded the corresponding 2-amino-
5-arylazothiazoles 2a–c. The structure of the synthe-
sized compounds was confirmed by elemental and
spectrochemical analyses. The infrared spectrum of 2c
exhibited bands at 1640 (C═N) and 3384, 3263 cmÀ1
1
(NH2). The H NMR spectrum of 2c showed the signal
of aromatic protons as two doublet signals at δ = 7.50
and 8.25 ppm, a singlet signal at δ 7.80 for the C-4
thiazole ring proton, and a singlet signal at δ = 8.55 due
to NH2 protons. 2-Amino-5-arylazothiazoles 2a-c were
reacted with chloroacetyl chloride in DMF containing some
drops of triethyl amine to afford the corresponding 5-
arylazo-2-(N-chloroacetyl)amino-thiazole derivatives 3a–c
(Scheme 1). The chemical structures of 3a–c were secured
by elemental and spectral analyses. The IR spectrum of, for
example, 3b revealed intense bands at 1695 and 3204cmÀ1
assignable to the (C═O) and (NH) functions, respectively.
1
The H NMR spectrum of 3b revealed two singlet signals
© 2014 HeteroCorporation

M. E. Khalifa, E. Abdel-Latif, and A. A. Gobouri
Vol 000
Scheme 1. Synthesis of 5-Arylazo-2-(N-chloroacetyl)amino-thiazoles 3a–c.
at δ 2.35 and 4.10 ppm due to the CH3 and CH2 protons, two
doublet signals at δ 7.25 and 7.50 ppm for aromatic protons,
a singlet signal at δ 7.70 for the C-4 thiazole proton, and a
singlet signal at δ 11.10 due to NH proton.
Addition reaction of ethyl cyanoacetate, cyanoacetamide,
and ethyl acetoacetate with phenyl isothiocyanate in
DMF and potassium hydroxide afforded the correspond-
ing thiocarbamoyl derivatives 4a, 4b, and 4c [23,24],
which underwent condensation reaction with 5-arylazo-
2-(N-chloroacetyl)amino-thiazoles 3a–c in ethanol and
sodium ethoxide to furnish the corresponding ethyl 4-
amino-5-(5-arylazo-thiazol-2-ylcarbamoyl)-2-phenylamino-
thiophene-3-carboxylates 5a–c, 4-amino-5-(5-arylazo-thiazol-
2-ylcarbamoyl)-2-phenylamino-thiophene-3-carboxamides
6a–c, and ethyl 4-methyl-5-(5-arylazo-thiazol-2-ylcarba-
moyl)-2-phenylamino-thiophene-3-carboxylates 7a–c, re-
spectively (Scheme 2). The IR spectrum of, for example,
5b displayed bands at 1644 and 1662 cmÀ1 assignable to
the carbonyl functions and bands at 3384, 3312, and
1
3248 cmÀ1 for the NH and NH2 functions. The H NMR
spectrum of the same compound revealed a triplet signal
at δ 1.30 ppm due to methyl protons (OCH2CH3), a singlet
signal at δ 2.40 ppm for methyl protons (Ar-CH3), a quartet
signal at δ 4.25 ppm for methylene protons ((OCH2CH3), a
multiplet signal in the range δ 7.00–7.80 ppm for the aro-
matic protons and C-4 thiazole proton, a singlet signal at
δ 9.30 ppm corresponding to NH2 protons and two singlet
signals at δ 10.85 and 12.70 ppm for two NH protons.
Scheme 2. Synthesis of 5-(5-Arylazothiazol-2-yl)-2-phenylamino-thiophenes 5a–c, 6a–c, and 7a–c.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2014
2-Aminothiazole, Biological Activity, Disperse Dyes, Fastness Properties, Polyester
Fibers, and Thiophene
Dyeing and fastness properties. For dyeing polyester
fabrics, in practical terms, only disperse dyes are suitable.
Through their hydrophobic properties, these dyes are
capable of penetrating into the similarly hydrophobic
polyester fiber. The synthesized disperse dyes under
investigation were applied to polyester fabrics at 2%
color depth (weight of dye to fabric w.o.f.) using high-
temperature dyeing technique (pH 5.5, liquor ratio 20:1,
temperature 130°C for 60 min), where range of visual
color hues varied from yellow to brown were obtained.
The dyes on polyester fabrics were evaluated in terms of
their fastness properties and given in Table 1 using
standard method, where fastness to perspiration,
sublimation, and light were assessed in accordance with
AATCC-15 (1985), rubbing fastness test was assessed in
accordance with AATCC-88 (1988), and wash fastness
test was assessed in accordance with IS: 765–1979 [25].
The dyes obtained gave excellent leveling, uniformity of
coloration, and exhaustion of dye liquor. Furthermore,
excellent behavior in fastness to washing and perspiration
was shown. Most of the dyes have good rubbing fastness
and good sublimation fastness. The light fastness of the
synthesized dyes on polyester is significantly affected by
the nature of substituent in the diazo component. The
light fastness of each of the dyes was measured by
employing the standard method for determination of color
fastness of textiles. Several reports [26] suggested that
fading of azo dyes is mainly
a consequence of
decomposition of the –N═N– moiety by oxidation,
reduction or photolysis. The rates of these processes
should be sensitive to the chemical structure of the dye,
the type of substrate, and treatment conditions. Because
the dyed substrate employed in this study is polyester
fabrics (i.e., non-proteinic), the fading process likely
occurs by oxidation [27]. The ease of oxidation of azo
linkages should be a function of electron density.
Therefore, electron donating substituent on this moiety
should increase the fading rate. This proposal is in
agreement with the observed results (Table 1), which
demonstrate that the presence of a methyl group in
synthesized dyes causes decrease of light fastness to 3–4.
Color assessment. The colors of synthesized dyes on
polyester fabrics were expressed in terms of CIELAB
values (Table 2), and the following CIELAB coordinates
were measured by the reflectance spectrometer, where
(L*) values represent color lightness, chroma (C*) values
represent color purity, hue angle (h) values, which varies
from 0 to 360°, to specify the color related to the
principle colors, (a*) values represent the degree of
redness (positive) and greenness (negative), and (b*)
Table 1
Fastness properties of the synthesized dyes 5–7 on 100% polyester fabrics.
Perspiration
Acid Alkali
Rubbing
Sublimation fastness
Dye
Visual color
Brown
Yellowish brown
Pale brown
Pale brown
Yellowish brown
Pale brown
brown
Washing
Dry
Wet
Staining at 180ºC
Staining at 210ºC
Light (40 h)
5a
5b
5c
6a
6b
6c
7a
7b
7c
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
4
4–5
4
5
4
4
4
4–5
4
5–6
4
3–4
5
4–5
3–4
6
3–4
4
4
4
4–5
4
4–5
4
4–5
5
4–5
4
4–5
4–5
4–5
4
4–5
4
4–5
4
Reddish brown
brown
4–5
4
4–5
4
5
5
4–5
4–5
Table 2
Optical measurements of dyes 5–7.
Dye
K/S
L*
a*
b*
C*
h
ΔL
ΔC
ΔH
ΔE
5a
5b
5c
6a
6b
6c
7a
7b
7c
12.26
7.90
8.56
8.08
9.48
6.12
9.46
13.31
15.03
68.95
61.08
61.11
56.19
59.29
54.77
61.90
62.18
63.65
10.29
5.33
7.28
7.89
6.49
10.48
8.89
4.93
6.21
36.28
29.33
30.92
24.99
23.47
29.24
35.09
21.81
22.68
37.71
29.81
31.76
26.21
24.35
31.06
36.20
22.36
23.51
74.17
79.70
76.75
72.48
74.54
70.28
75.79
77.27
74.69
—
À7.87
À7.84
—
—
À7.90
À5.95
—
—
5.53
2.04
—
2.06
À2.20
—
—
7.68
6.85
—
3.03
3.10
—
3.1
À1.86
À1.42
4.85
—
—
0.28
1.75
À13.84
1.48
À1.10
6.32
5.95
À12.69
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

M. E. Khalifa, E. Abdel-Latif, and A. A. Gobouri
Vol 000
values represent the degree of yellowness (positive) and
blueness (negative). Also, color strength (K/S) values
were calculated at λmax and directly correlated with
the dye concentration on the dyed substrate according to
the Kubelka–Munk equation: K/S = (1-R)2/2R, where
K = absorbance coefficient, S = scattering coefficient, and
R = reflectance ratio. The difference in color strength
depends on the substitutes present and/or the position
of the substitutes on the structure of the synthesized
dyes. A chromophore-containing compound is called a
“chromogen”: its color depends on the nature, number,
and position of the “auxochromes”. Auxochromes may
shift the absorption towards higher wavelengths and thus
the color of the dye will deepen. Such groups are called
“bathochromes” (i.e., having electron-donating substitutes
such as OH, NH2 and CH3); these are said to have a
bathochromic effect. A group having the opposite,
hyposochromic, effect is called a “hypochrome” (i.e.,
having electron-attracting substitutes such as CHO, COR,
and NO2). As shown in Table 2, the application of the
dyes 5–7 on polyester fabrics showed that such dyes had
good affinity to polyester fabrics through the satisfactory
color yields and accepted values of K/S and the color hue
represented degrees of redness to yellowness color hue as
indicated from the positive values of a* and b* on the
red–green axis. The dyes 6 found to be lighter than the
other derivatives 5 and 7 according to the color lightness
values L*. These results were in line with the previously
reported by Műller on the effect of substituent in the dye
structure and hue [28].
and Staphylococcus aureus), Gram-negative bacteria
(Escherichia coli and Pseudomonas aeruginosa), and
fungi (Aspergillus flavus and Candida albicans) using
the agar dilution method [29], and their inhibition
zones’ diameter were given in Table 3. In general, the
synthesized dyes displayed uniform antimicrobial
activities and approximately half effect of the standard
antibacterial agent (Tetracycline) against the different
strains tested (>10 mm inhibition zone). On the other
hand, they showed no activities against all of the tested
fungi used in this study. The enhanced antibacterial
activity is clearly linked to the introduction of ester group
in the thiophene moiety (e.g., 7b) and/or nitro group at
the side chain of the backbone of the molecule (e.g., 7c) as
electron withdrawing groups, while presence of electron
donating groups such as amino, amide, and methyl groups
(e.g., compounds 5, 6a–c, and 7a) deactivate the thiophene
moiety against tested bacteria.
MIC90 determination. Minimum inhibitory concentration,
which inhibits 90% of the bacterial count compared with
control microorganism, was evaluated, where compound 7b
was selected, for example, because of its highly active
behavior among other samples against both types of bacteria
(S. aureus and E. coli). It was found out that the minimum
inhibitory concentration (MIC90) of 7b against S. aureus
(G+) was 164μg/mL, comparing with Tetracycline as
standard (104 μg/mL) indicating its acceptable efficiency.
CONCLUSION
Screening of antimicrobial activities for the synthesized
A series of novel monoazo disperse dyes were synthesized
based on 5-(5-arylazo-thiazol-2-ylcarbamoyl)-2-phenyl-
amino-thiophenes by cyclocondensation of 5-arylazo-2-(N-
chloroacetyl)amino-thiazoles with various thiocabamoyl
dyes.
The antimicrobial activities of the synthesized
dyes 5a–c, 6a–c and 7a–c were screened against selected
species of test strains, as per the ASTM specifications,
from Gram-positive bacteria and fungi (Bacillus subtilis
Table 3
The inhibition zone (mm) values of the synthesized compounds 5a–c, 6a–c, and 7a–c.
Inhibition zone diameter (mm/mg sample)
Bacillus
Staphylococcus
Escherichia
Pseudomonas
Aspergillus
flavus (Fungus)
Candida albicans
Sample
subtilis (G+)
aureus (G+)
coli (G-)
aeruginosa (G-)
(Fungus)
Standard Tetracycline
30
28
30
31
0.0
16
0.0
20
Antibacterial Agent
Amphotericin B
—
—
—
—
Antifungal agent
5a
5b
5c
6a
6b
6c
7a
7b
7c
12
12
14
14
10
11
9
13
13
13
14
14
10
10
17
15
12
14
10
15
12
10
12
15
15
13
12
12
14
10
10
9
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
13
13
14
14
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2014
2-Aminothiazole, Biological Activity, Disperse Dyes, Fastness Properties, Polyester
Fibers, and Thiophene
filtered. The obtained 2-amino-5-arylazothiazoles were dried
and recrystallized from the appropriate solvent.
derivatives. All of the synthesized dyes were then applied for
dyeing 100% polyester fabrics by using high temperature
dyeing method at 130°C. The dyed polyester fabrics, which
display yellowish brown to brown hues, exhibited very good
fastness to washing, perspiration, and sublimation fastness
properties with little variation in the good to excellent
rubbing and moderate light fastness depending on the
amount of dye fixed. Finally, all the synthesized dyes
exhibited antimicrobial efficiency against Gram-positive
bacteria (B. subtilis and S. aureus), Gram-negative bacteria
(E. coli and P. aeruginosa), with various degrees according
to the chemical structure of the synthesized dyes and
attached functional groups, while showed no activities
against fungi used in this study (A. flavus and C. albicans).
2-Amino-5-phenylazo-thiazole (2a).
Reddish brown solid
(EtOH); yield 84%; mp 270–1ºC; Lit. mp 270–271ºC [30].
2-Amino-5-(p-tolyl)azo-thiazole (2b).
Brown solid (EtOH);
yield 73%; mp 207–209ºC; Lit. mp 205ºC [31].
2-Amino-5-(p-nitrophenyl)azo-thiazole (2c).
Brown solid
(EtOH); yield 80%; mp 167–169ºC; IR: ν = 1640 (C═N),
1
3384, 3263 (NH2) cmÀ1; H NMR (300 MHz, DMSO): δ =7.50
(d, 2H, Ar-H), 7.80 (s, 1H, C-4 thiazole-H), 8.25 (d, 2H, Ar-H),
8.55 (s, 2H, NH2). Anal. Calcd for C9H7N5O2S (MW: 249.25): C,
43.37; H, 2.83; N, 28.10%. Found: C, 43.28; H, 2.86;
N, 28.14%.
Synthesis of 2-[N-(Chloroacetyl)amino]-5-arylazo-thiazoles
(3a–c).
To a solution of 2-amino-5-arylazothiazoles 2a–c
(10 mM) in 25 mL DMF containing 0.5 mL triethyl amine,
chloroacetyl chloride (1.2 mL, 15 mM) was added dropwise with
stirring at room temperature. Stirring was continued for 2 h, and
the reaction mixture was poured to ice cooled water. The
precipitate that formed was collected by filtration, dried, and
recrystallized from the appropriate solvent.
EXPERIMENTAL
All melting points were determined using Stuart SMP 20 melt-
ing point apparatus (Bibby Scientific Limited, Staffordshire, UK).
Infrared spectra were recorded on a Perkin Elmer Alpha
platinium-ATR spectrometer (Perkin Elmer Co., Shelton, UK),
and 1H NMR spectra were measured on a Bruker WP 300 (Bruker
Co., MA, USA), in CDCl3 and/or DMSO as solvent, using TMS
as an internal standard. All the microanalysis and spectral analy-
sis were performed by Micro analytical centers of Taif (IR,
CHNS) and King Abdel-Aziz universities (1H NMR analysis),
Kingdom of Saudi Arabia. Microanalysis of the elements: car-
bon, hydrogen, and nitrogen was performed using Perkin-Elmer
2400 Analyzer, series II (Perkin Elmer Co., Shelton, UK). The
results were in satisfactory agreement with the calculated
values. The dyeing process was carried out using Galvanin-
Marino VI dyeing machine (Galvanin Co., Saint Marino, Italy),
the colorimetric measurements for the dyed polyester fabrics
were carried out using a reflectance GretagMacbeth CE 7000a
spectrophotometer (GretagMacbeth Co., Windsor, USA). Fast-
ness to washing was carried out using the automatic launder
Rota dyer (Texcare Co., Delhi, India), sponsored by the British
Standard Institute – Society of Dyers and Colourists, fastness to
perspiration was assessed according to the test sponsored by the
(BSS), fastness to rubbing was carried out according to the
standard method of testing (BSS) using Crock meter FD-17
type (Electric Hungarian Co., Budapest, Hungary), fastness to
sublimation was carried out using the scorch tester M247 A
(Atlas Electric Devices Co., Chicago, IL, USA) and fastness
to light was carried out using the “Weather-o-meter” (Atlas
Electric Devices Co., Chicago, IL USA), AATCC standard test
method. Dyeing processes, color assessments, and color fast-
ness properties were performed by Chemical laboratory,
Dakahlia for Spinning and Weaving Company, Mansoura,
Egypt. Antimicrobial tests were performed by the Biological
Analysis Centre, Cairo University, Egypt.
2-[N-(Chloroacetyl)amino]-5-phenylazo-thiazole (3a). Greenish
yellow solid (EtOH); yield 78%; mp 220–222ºC; IR: ν =1686
1
(C═O), 3234 (NH) cmÀ1; H NMR (300 MHz, CDCl3): δ =4.10
(s, 2H, CH2), 7.10–7.50 (m, 5H, Ar-H), 7.70 (s, 1H, C-4
thiazole-H), 11.55 (s, 1H, NH). Anal. Calcd for C11H9ClN4OS
(MW: 280.73): C, 47.06; H, 3.23; N, 19.96%. Found: C, 47.18;
H, 3.26; N, 19.91%.
2-[N-(Chloroacetyl)amino]-5-(p-tolyl)azo-thiazole (3b).
llowish brown solid (EtOH); yield 82%; mp 235–237ºC; IR: ν
= 1695 (C═O), 3204 (NH) cmÀ1 1H NMR (300 MHz, CDCl3):
Ye-
;
δ =2.35 (s, 3H, CH3), 4.10 (s, 2H, CH2), 7.25 (d, 2H, Ar-H),
7.50 (d, 2H, Ar-H), 7.70 (s, 1H, C-4 thiazole-H), 11.10 (s, 1H,
NH). Anal. Calcd for C12H11ClN4OS (MW: 294.76): C, 48.90;
H, 3.76; N, 19.01%. Found: C, 48.79; H, 3.70; N, 19.08%.
2-[N-(Chloroacetyl)amino]-5-(p-nitrophenyl)azo-thiazole (3c). Dark
brown solid (EtOH-DMF); yield 85%; mp 186–187ºC; IR: ν
= 1705 (C═O), 3276 (NH) cmÀ1
;
1H NMR (300 MHz,
DMSO): δ 4.20 (s, 2H, CH2), 7.50 (d, 2H, Ar-H), 7.80 (s, 1H,
C-4 thiazole-H), 7.50 (d, 2H, Ar-H), 12.35 (s, 1H, NH). Anal.
Calcd for C11H8ClN5O3S (MW: 325.73): C, 40.56; H, 2.48; N,
21.50%. Found: C, 40.61; H, 2.46; N, 21.46%.
General procedure for the synthesis of thiocarbamoyl
derivatives (4a–c).
The thiocarbamoyl derivatives were
prepared according to the previous literature [23,24].
General procedure for the synthesis of 2-(Phenylamino)-5-
(5-arylazothiazol-2-yl)-thiophenes 5-(7a–c).
A mixture of
thiocarbamoyl derivatives 4a–c (5 mM) was heated with sodium
ethoxide solution (5 mM, 0.1 g sodium metal in 10 mL absolute
ethanol), then the chloroacetyl derivative 3a–c (5 mM) was
added. The mixture was refluxed for 15 min. The resultant solid
product was collected by filtration, dried, and recrystallized
from the appropriate solvent.
4-Amino-3-carbethoxy-2-(phenylamino)-5-(5-phenylazothiazol-
General procedure for synthesis of 2-Amino-5-arylazothiazoles
2-yl)-thiophene (5a).
Brown solid (EtOH); yield 74%; mp
(2a–c).
A solution of sodium nitrite (0.70 g, 10 mM) in 10mL
186–187ºC; IR: ν = 1646, 1658 (C═O), 3417, 3352, 3218 (NH
1
and NH2) cmÀ1; H NMR (300 MHz, CDCl3): δ = 1.30 (t, 3H,
water was gradually added to a well-cooled solution of the
aromatic amine (10 mM) in conc. HCl (3.0 mL). The
diazonium salt solution was added with continuous stirring
to an ice cooled solution of the 2-aminothiazole 1 (1 g,
10 mM) in ethanol (50 mL) and sodium acetate (3.8 g). The
reaction mixture was allowed to stand for 2 h and then
CH3), 4.25 (q, 2H, CH2), 7.00–7.70 (m, 11H, Ar-H and C-4
thiazole-H), 8.65 (s, 2H, NH2), 10.45 (s, 1H, NH), 12.20
(s, 1H, NH). Anal. Calcd for C23H20N6O3S2 (MW: 492.57):
C, 56.08; H, 4.09; N, 17.06%. Found: C, 56.26; H, 4.16;
N, 17.02%.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

M. E. Khalifa, E. Abdel-Latif, and A. A. Gobouri
Vol 000
4-Amino-3-carbethoxy-2-(phenylamino)-5-[5-(p-tolyl)azothiazol-
2-yl]-thiophene (5b). Yellowish brown solid (EtOH); yield
62%; mp 180–181ºC; IR: ν = 1644, 1662 (C═O), 3384, 3312,
3248 (NH and NH2) cmÀ1 1H NMR (300 MHz, CDCl3):
δ = 1.30 (t, 3H, CH3), 2.40 (s, 3H, CH3), 4.25 (q, 2H,CH2),
7.00–7.80 (m, 10H, Ar-H and C-4 thiazole-H), 9.30 (s, 2H,
NH2), 10.85 (s, 1H, NH), 12.70 (s, 1H, NH). Anal. Calcd for
C24H22N6O3S2 (MW: 506.6): C, 56.90; H, 4.38; N, 16.59%.
Found: C, 56.77; H, 4.32; N, 16.67%.
81%; mp 160–161ºC; IR: ν = 1644, 1665 (C═O), 3308, 3216,
(NH) cmÀ1 1H NMR (300 MHz, CDCl3/DMSO): δ = 1.30 (t,
3H, CH3), 2.70 (s, 3H, CH3), 4.30 (q, 2H, CH2), 6.90–7.70
(m, 8H, Ar-H and C-4 thiazole-H), 8.20 (d, 2H, Ar-H),
10.20 (s, 1H, NH), 11. (s, 1H, NH). Anal. Calcd for
C24H20N6O5S2 (MW: 536.58): C, 53.72; H, 3.76; N,
15.66%. Found: C, 53.87; H, 3.78; N, 15.57%.
;
;
Dye bath preparation and dyeing procedure. Dispersion
of the dye was produced by dissolving the appropriate amount
of dye (0.1 g dye/5 g fiber, 2% shade) in 1 mL acetone and
then added drop wise with stirring to a solution of Setamol WS
(0.5–1.5), an anionic dispersing agent of BASF (sodium salt of
a condensation product of naphthalene sulfonic acid and
formaldehyde). The dyestuff dispersion was then added to the
dye bath at 60ºC through a fine mesh sieve or filter cloth. The
dye bath was prepared with liquor ratio 20:1 using sealed
stainless steel dye pots of 250 mL capacity in “Galvanin-Marino
VI-Italy” dyeing machine. Additional dispersing agent (0.5–1.0 g/L
Setamol WS of BASF) was added and the pH of the bath
adjusted to 5.5 using glacial acetic acid. The polyester fabric
was immersed and dyeing carried out by raising the dye bath
temperature from 20 to 130ºC at a rate of 3ºC/min and holding
at this temperature for 60 min before rapidly cooling to 50ºC at
9.9ºC/min. The dyed fabric was then rinsed with cold water,
reduction-cleared using mixture of 2 mL/L caustic soda solution
32.5% (71ºTw), 2 g/L sodium hydrosulphite and 0.5 g/L Hostapal
CV conc., non-ionic wetting agent of Clariant, at 75–85ºC for
15–30min and soaped with 2% non-ionic detergent and ammonia
(pH 8.5) at 50ºC for 30 min to improve washing fastness then
drying in a pre-drier without contact up to a residual moisture of
approximately 30% followed by final drying which be carried out
on a hot flue.
4-Amino-3-carbethoxy-2-(phenylamino)-5-[5-(p-nitrophenyl)
azothiazol-2-yl]-thiophene (5c).
Brown solid (EtOH-DMF);
yield 78%; mp 172–173ºC; IR: ν = 1650, 1664 (C═O), 3422,
1
3367, 3274 (NH and NH2) cmÀ1; H NMR (300 MHz, CDCl3/
DMSO): δ = 1.30 (t, 3H, CH3), 4.30 (q, 2H, CH2), 7.10–7.70 (m,
8H, Ar-H and C-4 thiazole-H), 8.05 (d, 2H, Ar-H), 9.80 (s, 2H,
NH2), 11.75 (s, 1H, NH), 12.70 (s, 1H, NH). Anal. Calcd for
C23H19N7O5S2 (MW: 537.57): C, 51.39; H, 3.56; N, 18.24%.
Found: C, 51.46; H, 3.52; N, 18.32%.
4-Amino-2-(phenylamino)-5-(5-phenylazothiazol-2-yl)-thiophene-
3-carboxamide (6a). Yellowish brown solid (EtOH); yield 72%;
mp 230–232ºC; IR: ν =1645 (C═O), 3411, 3346, 3262 (NH and
NH2) cmÀ1 1H NMR (300 MHz, CDCl3/DMSO): δ = 7.10-7.80
;
(m, 11H, Ar-H and C-4 thiazole-H), 9.25 (s, 2H, NH2), 10.10
(s, 2H, NH2), 11.80 (s, 1H, NH), 13.05 (s, 1H, NH). Anal. Calcd
for C21H17N7O2S2 (MW: 463.54): C, 54.41; H, 3.70; N, 21.15%.
Found: C, 54.20; H, 3.62; N, 21.22%.
4-Amino-2-(phenylamino)-5-[5-(p-tolyl)azothiazol-2-yl]-thio-
phene-3-carboxamide (6b).
64%; mp 195–196ºC; IR: ν = 1648 (C═O), 3384, 3342, 3262
(NH and NH2) cmÀ1 1H NMR (300 MHz, CDCl3/DMSO):
Brown solid (EtOH); yield
;
δ = 2.40 (s, 3H, CH3), 7.10–7.85 (m, 10H, Ar-H and C-4
thiazole-H), 8.90 (s, 2H, NH2), 9.90 (s, 2H, NH2), 11.70 (s,
1H, NH), 12.85 (s, 1H, NH). Anal. Calcd for C22H19N7O2S2
(MW: 477.56): C, 55.33; H, 4.01; N, 20.53%. Found: C,
55.12; H, 4.07; N, 20.62%.
Color fastness tests.
The color fastness properties of the
dyed fabrics against washing, perspiration, rubbing, sublimation,
and light were evaluated using standard methods [25]. Results
were listed in Table 1, where the staining of adjacent cotton
fabrics was assessed using the gray scale: 1-poor, 2-fair, 3-moderate,
4-good, and 5-excellent, other than light fastness, which is scaled from
1–8 on the gray scale.
4-Amino-2-(phenylamino)-5-[5-(p-nitrophenyl)azothiazol-
2-yl]-thiophene-3-carboxamide (6c).
(EtOH); yield 62%; mp 171–173ºC; IR: ν = 1651 (C═O), 3412,
3440, 3267 (NH and NH2) cmÀ1 1H NMR (300 MHz,
Dark brown solid
;
DMSO): δ = 7.20–7.80 (m, 8H, Ar-H and C-4 thiazole-H), 8.20
(d,2H, Ar-H), 9.15 (s, 2H, NH2), 10.15 (s, 2H, NH2), 11.65 (s,
1H, NH), 12.80 (s, 1H, NH). Anal. Calcd for C21H16N8O4S2
(MW: 508.53): C, 49.60; H, 3.17; N, 22.03%. Found: C,
49.82; H, 3.10; N, 22.09%.
Color assessment.
The colorimetric measurements of the
dyed fabric (Table 3) were assessed in terms of tristimulus
colorimetry values. The values of the chromaticity coordinates,
luminance factor, and the positions of colors in the CIELAB
color solid were reported.
3-Carbethoxy-4-methyl-2-(phenylamino)-5-(5-phenylazothiazol-2-
Antimicrobial test method. The agar dilution method was
used to evaluate the antimicrobial activity of the synthesized
dyes 5a–c, 6a–c, and 7a–c. Stationary-phase cultures of bacteria
were prepared at 37°C and used to inoculate fresh 5.0 mL
culture to an OD600 of 0.05. The 5.0 mL cultures were then
incubated at 37°C until an OD600 of 0.10 was achieved, from
which standardized bacterial suspensions were prepared to a final
cell density of 6 × 105 colony forming unit/mL. Serial dilutions
from the treatments (0–320 μg/mL) were prepared and mixed
with 5.0 mL of the standardized bacteria suspension then
added to the plates and incubated for 24 h at 37°C. The
colony forming units were counted for each dilution (NCCLS:
M7 – A4, 1997). The antimicrobial activity was evaluated by
measuring the average of inhibition zone diameter against the
test microorganisms and the values were expressed in
millimeter. The relationships between the biological activity
and the chemical structure of the synthesized compounds and
their dyed fabrics were discussed.
yl)-thiophene (7a).
Brown solid (EtOH); yield 77%; mp
192–193ºC; IR: ν = 1641, 1661 (C═O), 3311, 3256 (NH) cmÀ1
;
1H NMR (300MHz, CDCl3): δ = 1.30 (t, 3H, CH3), 2.70 (s, 3H,
CH3), 4.30 (q, 2H, CH2), 6.90–7.70 (m, 11H, Ar-H and C-4
thiazole-H), 10.15 (s, 1H, NH), 11.80 (s, 1H, NH). Anal. Calcd
for C24H21N5O3S2 (MW: 491.59): C, 58.64; H, 4.31; N, 14.25%.
Found: C, 58.48; H, 4.26; N, 14.28%.
3-Carbethoxy-4-methyl-2-(phenylamino)-5-[5-(p-tolyl)azo-
thiazol-2-yl]-thiophene (7b). Brown solid (EtOH); yield 83%;
mp 174–175ºC; IR: ν = 1640, 1664 (C═O), 3288, 3214 (NH)
1
cmÀ1; H NMR (300 MHz, CDCl3): δ = 1.30 (t, 3H, CH3), 2.35
(s, 3H, CH3), 2.70 (s, 3H, CH3), 4.30 (q, 2H, CH2), 6.90–7.80 (m,
10H, Ar-H and C-4 thiazole-H), 10.25 (s, 1H, NH), 11.70 (s, 1H,
NH). Anal. Calcd for C25H23N5O3S2 (MW: 505.61): C, 59.39; H,
4.59; N, 13.85%. Found: C, 59.46; H, 4.62; N, 13.78%.
3-Carbethoxy-4-methyl-2-(phenylamino)-5-[5-(p-nitrophenyl)
azothiazol-2-yl]-thiophene (7c).
Brown solid (EtOH); yield
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2014
2-Aminothiazole, Biological Activity, Disperse Dyes, Fastness Properties, Polyester
Fibers, and Thiophene
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Acknowledgments. The authors want to dedicate this work with
great honor and attitude to their master, Prof. Dr. Mohamed A.
Metwally (May God bless and rest his soul) for his fabulous
efforts as long as his life, serving the human beings in the field
of teaching and scientific research.
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Journal of Heterocyclic Chemistry
DOI 10.1002/jhet