Eco-friendly synthesis of some thiosemicarbazones and their applications as intermediates for 5-arylazothiazole disperse dyes

Article abstract of DOI:10.3390/molecules201219820

The solid-solid reactions of thiosemicarbazide with 4-formylantipyrine, 2-acetylpyrrole and camphor were performed to afford the thiosemicarbazones 1-3 which underwent hetero-cyclization with phenacyl bromide to furnish the corresponding thiazole derivatives 4-6. The yields of the reactions are quantitative in all cases and the products do not require further purification. A series of 5-arylazo-2-(substituted ylidene-hydrazinyl)-thiazole dyes 7-9 was then prepared by diazo coupling of thiazole derivatives 4-6 with several diazonium chlorides. The synthesized dyes were applied as disperse dyes for dyeing polyester fabric. The dyed fabrics exhibit good washing, perspiration, sublimation and light fastness properties, with little variation in their moderate to good rubbing fastness.

Full text of DOI:10.3390/molecules201219820

Article
Eco-Friendly Synthesis of Some Thiosemicarbazones
and Their Applications as Intermediates for
5-Arylazothiazole Disperse Dyes
Hatem E. Gaffer 1 and Mohamed E. Khalifa 2,3,
*
Received: 13 November 2015 ; Accepted: 3 December 2015 ; Published: 9 December 2015
Academic Editor: Philippe Belmont
1
Textile Research Division, National Research Center, Dokki 12622, Egypt; hatem197@yahoo.com
Department of Chemistry, Faculty of Science, Taif University, P. O. Box 888, Taif 21974, Saudi Arabia
Department of Chemical Engineering, Higher Institute for Engineering and Technology, Central Zone,
2
3
4th District, New Damietta, Damietta, Egypt
*
Correspondence: mohamedezzat200@hotmail.com or mohamedezzat@tu.edu.sa; Tel.: +966-569-846-966
Abstract: The solid-solid reactions of thiosemicarbazide with 4-formylantipyrine, 2-acetylpyrrole
and camphor were performed to afford the thiosemicarbazones 1–3 which underwent hetero-cyclization
with phenacyl bromide to furnish the corresponding thiazole derivatives 4–6. The yields of the
reactions are quantitative in all cases and the products do not require further purification. A series
of 5-arylazo-2-(substituted ylidene-hydrazinyl)-thiazole dyes 7–9 was then prepared by diazo
coupling of thiazole derivatives 4–6 with several diazonium chlorides. The synthesized dyes were
applied as disperse dyes for dyeing polyester fabric. The dyed fabrics exhibit good washing,
perspiration, sublimation and light fastness properties, with little variation in their moderate to
good rubbing fastness.
Keywords: solid-solid reactions; thiosemicarbazones; phenacyl bromide; 5-arylazothiazoles;
disperse dyes; fastness properties.
1. Introduction
Stoichiometric solid-solid reactions are most versatile for the waste-free production of a single
product, while melt reactions more frequently have the risk of side reactions, even if these are
considerably better than solution reactions. Solvent-free reactions have been reviewed without
emphasis of waste-free processes [1]. More than 1000 waste-free quantitative syntheses in organic
solid-state chemistry are already known and have been reported in a review article that covers more
than 25 reaction types [2]. Thiosemicarbazones are a class of interesting compounds presenting
a wide range of pharmacological applications as antitumor, antimicrobial and antiviral agents [3].
α-(N)-Heterocyclic thiosemicarbazones have been extensively investigated by many authors [4–9].
2. Results and Discussion
2.1. Chemistry
Thiosemicarbazones 1–3 were prepared quantitatively by room temperature ball-milling
thiosemicarbazide with 4-formylantipyrine, 2-acetylpyrrole and camphor, respectively (Scheme 1).
˝
The water of reaction can be removed by heating to 80 C in a vacuum (Scheme 1). The solid-state
condensation is quantitative and more effective than the reported solution reactions (1, 88% [10];
2, 56% [11]; 3, 85% [12]). We have been able to increase the yield in various instances from
moderate in solution to quantitative by applying solid–solid techniques without any solvent [13–15].
Molecules 2015, 20, 21982–21991; doi:10.3390/molecules201219820
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Molecules 2015, 20, 21982–21991
Thus, thio- semicarbazones are now most readily available without producing wastes from versatile
condensations of thiosemicarbazides and aldehydes or ketones. We present here the synthetic use of
these environmentally benign building blocks in various heterocyclization reactions.
S
NH2
H2N
N
H
Ball-Milling, 100%
Me
Me
CHO
O
S
N
O
N
N
Ph
H
Me
O
S
Me
Me
Me
S
N
N
NH2
N
NH2
N
N
NH2
N
N
N
Ph
H
H
N
H
H
Me
H
O
1
3
2
Scheme 1. Synthesis of thiosemicarbazones 1, 2 and 3 using the ball-milling technique at
room temperature.
Thiosemicarbazides are convenient precursors which have been extensively utilized in
heterocyclic synthesis [16]. Their reactions with compounds containing C=O and C=N groups is an
elegant method for the preparation of biologically active compounds viz. triazoles and thiazoles [17].
The waste-free solid-state reaction technique could also be applied to prepare the 2-(substituted
ylidene-hydrazinyl)-4-phenylthiazoles 4, 5 and 6. Stoichiometric ball milling reactions of phenacyl
bromide with 4-formylantipyrine thiosemicarbazone (1), 2-acetylpyrrole thiosemicarbazone (2) and
camphor thiosemicarbazone (3) afforded the corresponding iminium hydrobromide salts in 100%
yield without the aid of basic catalysts or solvents. The water of the reaction can be removed by
˝
evaporation at 80 C under vacuum without hydrolysis losses. Washing with aqueous Na2CO3
can easily liberate the 2-(substituted ylidene-hydrazinyl)-4-phenylthiazole free bases 4, 5 and 6
(Scheme 2). The suggested mechanism for the formation of compounds 4, 5 and 6 is outlined
in Scheme 3 and in agreement with previously reported results [18]. It is thought that the
reaction starts through nucleophilic attack of the thiolate group to form the non-isolable S-alkylated
intermediate, which via nucleophilic addition and intramolecular cyclocondensation accompanied
by water elimination, gave the corresponding thiazoles 4, 5 and 6. The chemical structures of 4–6
were elucidated on the basis of spectral techniques. The IR spectrum of 4 (for example) showed
´1
the characteristic absorption bands for NH, C=N and C=O stretching at 3121, 1614 and 1659 cm
.
1
The H-NMR spectrum of 4 displayed two singlet signals of six protons for two methyl groups at
δ 2.55 and 3.20 ppm, three singlet protons at δ 7.15, 8.35, and 9.60 ppm due to the thiazole H-5,
azomethine proton (CH=N), and NH proton, in addition to a multiplet signal centered around the
region 7.25–7.75 assigned to the ten aromatic protons of two phenyl rings. The mass spectrum of 4
showed a molecular ion peak at m/z = 389 (intensity 100%) corresponding to the correct molecular
weight for the molecular formula C21H19N5OS.
Diazo coupling of the synthesized 2-(substituted ylidene-hydrazinyl)-4-phenylthiazoles 4, 5
˝
and 6 with several aromatic diazonium chlorides proceeded in pyridine at 0–5 C to afford the
corresponding 5-arylazo-4-phenylthiazole derivatives 7, 8 and 9 respectively (Scheme 4).
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Molecules 2015, 20, 21982–21991
Thiosemicarbazones: 1-3
PhCOCH2Br
Ball-Milling, 100% yield
Ph
S
Ph
Me
Me
N
N
Ph
Me
N
N
N
Ph
N
N
S
N
H
N
S
N
H
N
H
N
H
O
H
Me
6
4
5
Scheme 2. Synthesis of 2-(substituted ylidene-hydrazinyl)-4-phenylthiazoles 4, 5 and 6.
H2N
S
R1
R2
S
O
100%
. HBr
N N C
R1
N
Br
Ph
+
H2N
N
H
C
O
Ph
R2
Ph
1-3
- H2O
Ph
R1
R1
R2
N
S
N
Na2CO3 - H2O
. HBr
NH N C
NH N C
R2
S
4-6
Scheme 3. The suggested solid-state mechanism for the reaction of phenacyl bromide and
thiosemicarbazones 1–6.
Thiazole Derivatives: 4-6
(1) ArNH2 + (NaNO2/HCl)
(2) Pyridine at 0-5 oC
Me
N
Ph
Ph
Me
H
N
N
Me
N
Ph
N
N
N
N
S
S
N
H
N
H
N
N
Ar
Ar
O
Ph
S
7
9
N
N
Ar
N
N
N
H
a: Ar = C6H5
b: Ar = p-MeC6H4
C: Ar = p-NO2C6H4
N
H
Me
8
Scheme 4. Synthesis of 5-arylazo-4-phenylthiazole derivatives 7, 8 and 9.
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Molecules 2015, 20, 21982–21991
The structures of the highly functionalized thiazolyl dyes 7–9 were assigned on the basis of their
elemental analyses and spectral data. For example, the IR spectrum of 7a exhibited the presence
1
of NH, C=O and C=N stretching bands at 3361, 1678 and 1632 cm´1, respectively. The H-NMR
spectrum of 7a revealed two singlet signals at δ 2.45 and 3.35 ppm corresponding to six protons
of two methyl groups (2CH3), a multiplet in the region δ 6.95–7.80 ppm due to aromatic protons,
a singlet signal at δ 8.30 ppm in due to methine proton (CH=N), in addition to a singlet signal
at δ 11.80 ppm due to NH proton. The mass spectrum of 7a (Ar = C6H5) showed a molecular ion
peak at m/z = 493 (intensity 81.7%) corresponding to the correct molecular weight for the molecular
formula C27H23N7OS.
2.2. Application
2.2.1. 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 functionalized 5-arylazo-4-phenyl-2-substituted-thiazole disperse dyes 7–9 were
˝
applied to polyester fabrics (o.w.f. 2%) by the high-temperature pressure technique (130 C) and a
range of color shades ranging from red to violet has been obtained. The dyes obtained gave excellent
leveling, uniformity of coloration and exhaustion of dye liquor. The dyeing of polyester fabrics
was evaluated in terms of their fastness properties (e.g., fastness to washing, perspiration, rubbing,
sublimation, and light) using a standard method [19]. The results are given in Table 1 and they reveal
that these dyes share good fastness properties.
Table 1. Fastness properties of the synthesized dyes on polyester fabrics.
Perspiration
Rubbing
Sublimation
Dye
Washing
Light (60 h)
Acid Alkali
Dry Wet Staining at 180 ˝C Staining at 210 ˝C
7a
7b
7c
8a
8b
8c
9a
9b
9c
4–5
4–5
4–5
4–5
4–5
4–5
4–5
4–5
4–5
4
4–5
4
4–5
4–5
4–5
4
4
4–5
4
4–5
3
3–4
3–4
4
3
3
4
4
4–5
3
4–5
4
4
3
3
4–5
4–5
3–4
4
4
3–4
3–4
4
4
4
4
3
4
4
3
4
3–4
4
3–4
4
5–6
3–4
6
6
4
5–6
5–6
4
4
4–5
4–5
4
4–5
4–5
4
4–5
6
The light fastness of the synthesized dyes on polyester is significantly affected by the nature
of substituent in the diazo component, where the fading of azo dyes is mainly a consequence of
decomposition of the -N=N- moiety by oxidation, reduction and/or photolysis [20]. The rates of these
processes should be sensitive to the chemical structure of the dye, the type of substrate and treatment
conditions. Since the dyed substrate employed in this study is a polyester fabric (i.e., non-proteinic),
the fading process likely occurs by oxidation [21]. 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 the synthesized dyes causes a decrease of light fastness to 3–4.
2.2.2. Color Assessment
The color on polyester fibers is expressed in terms of CIELAB values (Table 2) and the following
˝
˝
CIELAB coordinates are measured: lightness (L*), chroma (C*), hue angle (h) from 0 to 360 ,
(a*) value represents the degree of redness (positive) and greenness (negative) and (b*) represents
the degree of yellowness (positive) and blueness (negative). K/S values given by the reflectance
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Molecules 2015, 20, 21982–21991
spectrometer are calculated at λ
and are directly correlated with the dye concentration on the
max
dye substrate according to the Kubelka–Munk equation: K/S = (1 ´ R)2/2R, where K = absorbance
coefficient, S = scattering coefficient, 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. The presence of bathochromes “electron-donating substitutes” such as methyl group (i.e., 7b,
8b and 9b) deepen the color due to their bathochromic effect, whereas presence of hypochromes
“electron-attracting substitutes” such as nitro group (i.e., 7c, 8c and 9c) make the opposite effect on
color strength due to their hypsochromic shift.
As shown in Table 2, application of the synthesized compounds 7(a–c)–9(a–c) as disperse dyes,
showed the good affinity of such dyes to polyester fabrics, as indicated from the satisfactory color
yields and the acceptable K/S values.
Table 2. Optical measurements of the synthesized dyes on polyester fabrics.
Exhaustion
(%)
Molar
Absorbitivity ε
Absorption
Dye
K/S
L*
a*
b*
C*
H
λ
max/nm
1.42 ˆ 105
1.18 ˆ 105
1.89 ˆ 104
1.17 ˆ 105
1.22 ˆ 105
2.11 ˆ 105
1.08 ˆ 105
1.17 ˆ 105
1.41 ˆ 105
7a
7b
7c
8a
8b
8c
9a
9b
9c
61
64
61
62
62
65
62
63
65
451
417
447
453
444
452
464
451
443
10.31 81.07
13.87 40.99
3.34
3.32
20.41 51.03 67.49
41.81 44.88 66.24
10.23 74.23 ´1.23 37.20 55.34 80.62
11.24 89.36
11.46 72.91
13.72 73.22
5.35
5.22
0.37
3.14
53.62 76.96
47.57 48.46 82.52
23.11 47.56 84.88
11.07 65.51 ´1.44 30.77 44.39 80.63
11.57 80.93 ´1.05 14.02 51.74 74.65
11.68 80.34 ´0.56 16.23 55.23 66.09
Figure 1 illustrates the relationship between the dyeing bath concentrations and the strengths of
the synthesized 7(a–c)–9(a–c) disperse dyes (K/S), under high temperature (HT) dyeing conditions,
where no direct correlation between the relative molecular mass of these dyes to the build-up was
apparent. This probably reflects the importance of other parameters such as dye solubility, which in
turn is dictated by the type of structural features within the dye. These results are in line with the
previously reported by Müller [22] on the relation between substituents and dye structure.
Figure 1. Comparison of K/S values for the synthesized disperse dyes 7–9 series.
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Molecules 2015, 20, 21982–21991
In general, the color hues of the thiazolyl dyes 7(a–c)–9(a–c) on polyester fabric are shifted to the
greenish direction, as indicated by the negative values of a* (red-green axis). The positive values of
b* (yellow-blue axis) indicate that the color hues of the thiazolyl—azo dyes 7a–c, 8a–c and 9a–c on
polyester fabric are shifted to the yellowish direction.
3. Experimental Section
3.1. Materials and Methods
3.1.1. Chemicals and Reagents
All the chemicals and solvents used in this study were obtained from Merck (Darmstadt, Germany)
and Sigma-Aldrich chemical company (St. Louis, MO, USA).
3.1.2. Instrumentation
Melting points were determined with a Gallenkamp melting point apparatus (capillary method,
Gallenkamp Co., London, UK) and are uncorrected. Elemental analyses were carried out at the
Microanalytical Unit of National Research Center and Faculty of Science, Mansoura University; the
results were in satisfactory agreement with the calculated values. IR spectra (KBr) were recorded
with a Matteson 5000 FTIR spectrometer (Shimadzu Co., Kyoto, Japan, not all frequencies are
1
reported). The H-NMR spectra were acquired using a WP 300 spectrometer (Bruker Co., Billerica,
MA, USA) at 300 MHz (1H) in broad band mode. Mass spectra were obtained at a Finnigan MAT
212 instrument (Finnigan MAT Co., Bremen, Germany) by electron impact at 70 eV. The ball-mill was
a Retsch MM 2000 swing mill (Retsch, Haan, Germany) with a 10-mL stainless steel, double-walled
beaker with fittings for circulating coolants. Two stainless steel balls of 12 mm diameter were used.
Ball-milling was performed at 20–25 Hz frequency, usually at room temperature (without circulating
˝
liquid the temperature did not rise above 30 C). The colorimetric measurements for the dyed
polyester fabrics were carried out using a reflectance spectrophotometer (GretagMacbeth CE 7000a,
GretagMacbeth Co., Windsor, UK). Fastness to washing was carried out using the automatic Rotadyer
launder (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 a Crockmeter FD-17 apparatus
(Electric Hungarian Co., Budapest, Hungary), fastness to sublimation was carried out using 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) according to the AATCC
standard test method.
3.2. Synthesis
3.2.1. Solid-State Synthesis of Thiosemicarbazones 1–3
A mixture of thiosemicarbazide (0.182 g, 2.00 mmol) and 2.00 mmol of 4-formylantipyrine,
2-acetylpyrrole or camphor was ball-milled at room temperature for 1 h. The resulting solid powders
˝
were dried at 80 C under vacuum to give a 100% yield of the corresponding thiosemicarbazones 1, 2
and 3 that did not require any further purification.
˝
4-Formylantipyrine thiosemicarbazone (1). White solid; yield 100%; m.p. 219–220 C (Lit. yield 88%;
m.p. 217–219 C [10]); IR: v = 3378, 3236 (NH and NH2), 1682 (C=O) cm
˝
´1
;
1H-NMR (CDCl3):
δ = 2.45 (s, 3H, CH3), 3.20 (s, 3H, CH3N), 7.00–7.45 (m, 5H, Ar-H), 8.00 (s, 2H, NH2), 8.40 (s, 1H,
CH=N), 9.55 (s, 1H, NH). Anal. Calcd. for C13H15N5OS (289.36): C, 53.96; H, 5.23; N, 24.20%. Found:
C, 53.83; H, 5.28; N, 24.32%.
˝
2-Acetylpyrrole thiosemicarbazone (2). White solid; yield 100%; m.p. 192–193 C (Lit. yield 56%; m.p.
˝
1
193 C [11]); IR: v = 1642 (C=N), 3376, 3268, 3188 (NH and NH2) cm´1; H-NMR (CDCl3): δ = 2.20
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Molecules 2015, 20, 21982–21991
(s, 3H, CH3), 6.05 (q, 1H, pyrrole H-4), 6.50 (d, 1H, pyrrole H-3), 6.90 (d, 1H, pyrrole H-5), 8.25 (s, 2H,
NH2), 9.90 (s, 1H, NH), 11.45 (s, 1H, NH). Anal. Calcd. for C7H10N4S (182.25): C, 46.13; H, 5.53; N,
30.74%. Found: C, 46.34; H, 5.48; N, 30.62%.
˝
Camphor thiosemicarbazone (3). Yellow solid; yield 100%; m.p. 148–150 C (Lit. yield 85%; m.p.
˝
´1
;
1H-NMR (CDCl3):
147–150 C [12]); IR: v = 1590 (C=N), 3440, 3241, 3162 (NH and NH2) cm
δ = 0.75 (s, 3H, CH3), 0.95 (s, 6H, 2CH3), 1.20–1.30 (m, 2H, H-5 and H-6 endo), 1.70–1.80 (m, 2H,
H-5 and H-6 exo), 1.90–2.00 (m, 2H, H-3 endo and H-4), 2.35–2.40 (m, 1H, H-3 exo), 8.00 (s, 2H, NH2),
9.70 (s, 1H, NH). Anal. Calcd. for C11H19N3S (225.35): C, 58.63; H, 8.50; N, 18.65%. Found: C, 58.77;
H, 8.57; N, 18.56%.
3.2.2. Solid-State Synthesis of Thiazole Derivatives 4–6
A mixture of phenacyl bromide (0.398 g, 2.00 mmol) and thiosemicarbazone derivatives 1, 2, or 3
˝
(2.00 mmol) was ball-milled at room temperature for 1 h. After drying at 0.01 bar at 80 C quantitative
yields of the hydrobromide salts were obtained. The free bases 4–6 were obtained by washing the fine
powder of the corresponding hydrobromide salts with 5% Na2CO3 solution, followed by water and
˝
drying at 80 C under vacuum.
˝
2-(Antipyrin-4-ylmethylidenehydrazinyl)-4-phenylthiazole (4). Yellow solid; yield 98%; m.p. 235–237 C
˝
1
(Lit. yield 68%; m.p. 234–235 C [23]); IR: v = 3121(NH), 1614 (C=N), 1659 (C=O) cm´1; H-NMR
(CDCl3/DMSO): δ = 2.55 (s, 3H, CH3), 3.20 (s, 3H, CH3), 7.15 (s, 1H, thiazole H-5), 7.25–7.75 (m, 10H,
Ar-H and), 8.35 (s, 1H, CH=N), 9.60 (s, 1H, NH). MS (m/z, relative intensity): 389 (M+, 100%). Anal.
Calcd. for C21H19N5OS (389.47): C, 64.76; H, 4.92; N, 17.98%. Found: C, 64.55; H, 4.84; N, 17.86%.
2-[2-(1-(1H-Pyrrol-2-yl)ethylidene)hydrazinyl]-4-phenylthiazole (5). Yellow solid; yield 95%; m.p.
212–213 C (EtOH); IR: v = 3147 (NH), 1616 (C=N) cm´1; H-NMR (CDCl3): δ = 2.15 (s, 3H, CH3),
6.11–6.90 (m, 3H, pyrrole), 7.25 (s, 1H, thiazole H-5), 7.42–8.13 (m, 6H, Ar-H + NH), 9.65 (s, 1H, NH).
MS (m/z, relative intensity): 282 (M+, 88%). Anal. Calcd. for C15H14N4S (282.36): C, 63.80; H, 5.00;
N, 19.84%. Found: C, 63.91; H, 5.08; N, 19.72%.
˝
1
4-Phenyl-2-[2-(1,7,7-trimethylbicyclo[2.2.1]heptan-2-ylidene)hydrazinyl]thiazole (6). Yellow solid; yield
˝
97%; m.p. 254–255 C (EtOH); IR: v = 3168 (NH), 1609 (C=N) cm´1; 1H-NMR (CDCl3): δ = 0.90–1.05
(s, 9H, 3CH3), 1.30 (m, 2H, CH2), 1.70 (m, 2H, CH2), 1.90 (m, 2H, CH2), 2.30 (m, 1H, CH), 7.10–7.65
(m, 6H, Ar-H + thiazole H-5), 9.20 (s, 1H, NH). MS (m/z, relative intensity): 326 (M+ + 1, 100%). Anal.
Cacld. for C19H23N3S (325.47): C, 70.11; H, 7.12; N, 12.91%. Found: C, 70.27; H, 7.03; N, 13.03%.
3.2.3. Synthesis of 5-Arylazo-2-(arylidenehydrazino)-4-phenyl-thiazole Dyes 7–9
A cold solution of sodium nitrite (2 mmol) in water (5 mL) was added gradually to a cold
suspension of desired aromatic amine (2 mmol) in concentrated HCl (0.6 mL). The diazonium salt thus
obtained was added by continuous stirring to a cold solution of compound 4, 5 and/or 6 (2 mmol)
˝
in 10 mL of pyridine. The reaction mixture was stirred at 0–5 C for 2 h and diluted with water. The
solid was then filtered, dried, and recrystallized from ethanol or an ethanol-DMF mixture to afford
the corresponding 5-arylazothiazole derivatives 7, 8 and/or 9, respectively.
2-(Antipyrin-4-ylmethylidenehydrazinyl)-4-phenyl-5-phenylazo-thiazole (7a). Red solid; yield 87%; m.p.
185–86 C (EtOH); IR: v = 3361 (NH), 1678 (C=O) and 1632 (C=N) cm´1; 1H-NMR (DMSO): δ = 2.45
˝
(s, 3H, CH3), 3.35 (s, 3H, CH3N), 6.95–7.80 (m, 15H, Ar-H), 8.30 (s, 1H, CH=N), 11.80 (s, 1H, NH).
MS (m/z, relative intensity): 493 (M+, 81%). Anal. Calcd. for C27H23N7OS (393.58): C, 65.70; H, 4.70;
N, 19.86%. Found: C, 65.62; H, 4.66; N, 19.80%.
2-(Antipyrin-4-ylmethylidenehydrazinyl)-4-phenyl-5-(p-tolylazo)-thiazole (7b). Red solid; yield 76%; m.p.
˝
196–197 C (EtOH); IR: v = 3346 (NH), 1677 (C=O) and 1628 (C=N) cm´1; 1H-NMR (DMSO): δ = 2.30
(s, 3H, CH3), 2.50 (s, 3H, CH3), 3.35 (s, 3H, CH3N), 7.05–7.80 (m, 14H, Ar-H), 8.25 (s, 1H, CH=N), 11.20
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Molecules 2015, 20, 21982–21991
(s, 1H, NH). MS (m/z, relative intensity): 508 (M+ + 1, 76%). Anal. Calcd. for C28H25N7OS (507.61):
C, 66.25; H, 4.96; N, 19.32%. Found: C, 66.14; H, 4.90; N, 19.41%.
2-(Antipyrin-4-ylmethylidenehydrazinyl)-4-phenyl-5-(p-nitrophenlylazo)-thiazole (7c).
Reddish brown
˝
solid; yield 82%; m.p. 257–258 C (EtOH-DMF); IR: v = 3324 (NH), 1672 (C=O) and 1635 (C=N)
1
cm´1; H-NMR (DMSO): δ = 2.45 (s, 3H, CH3), 3.35 (s, 3H, CH3N), 7.10–8.10 (m, 14H, Ar-H), 8.25
(s, 1H, CH=N), 11.65 (s, 1H, NH). MS (m/z, relative intensity): 539 (M+ + 1, 58%). Anal. Calcd for
C27H22N8O3S (538.58): C, 60.21; H, 4.12; N, 20.81%. Found: C, 60.16; H, 4.03; N, 20.74%.
2-[2-(1-(1H-Pyrrol-2-yl)ethylidene)hydrazinyl]-4-phenyl-5-phenylazothiazole (8a). Reddish brown solid;
˝
1
yield 65%; m.p. 172–173 C (EtOH); IR: v = 3368, 3272 (NH), 1641 (C=N), cm´1; H-NMR (DMSO):
δ = 2.20 (s, 3H, CH3), 6.30–6.90 (m, 3H, pyrrole), 7.35–7.90 (m, 10H, Ar-H), 9.40 (s, 1H, NH), 11.55
(s, 1H, NH). MS (m/z, relative intensity): 386 (M+, 92%). Anal. Calcd. for C21H18N6S (386.47): C, 65.26;
H, 4.69; N, 21.75%. Found: C, 65.42; H, 4.61; N, 21.79%.
2-[2-(1-(1H-Pyrrol-2-yl)ethylidene)hydrazinyl]-4-phenyl-5-(4-methylphenyl)azothiazole (8b). Reddish brown
˝
solid; yield 78%; m.p. 247–248 C (EtOH-DMF); IR: v = 3344, 3234 (NH ), 1637 (C=N), cm´1; 1H-NMR
(DMSO): δ = 2.25 (s, 3H, CH3), 2.40 (s, 3H, CH3), 6.30–6.80 (m, 3H, pyrrole), 7.20–7.85 (m, 9H, Ar-H),
9.55 (s, 1H, NH), 11.40 (s, 1H, NH). MS (m/z, relative intensity): 400 (M+, 74%). Anal. Calcd for
C22H20N6S (400.50): C, 65.98; H, 5.03; N, 20.98%. Found: C, 65.82; H, 5.11; N, 20.87%.
2-[2-(1-(1H-Pyrrol-2-yl)ethylidene)hydrazinyl]-4-phenyl-5-(4-nitrophenyl)azothiazole (8c). Violet solid; yield
˝
80%; m.p. 237–238 C (EtOH); IR: v = 3334, 3254 (NH), 1651 (C=N) cm´1; 1H-NMR (DMSO): δ = 2.25
(s, 3H, CH3), 6.30–6.80 (m, 3H, pyrrole), 7.30–8.10 (m, 9H, Ar-H), 9.15 (s, 1H, NH), 11.35 (s, 1H, NH).
MS (m/z, relative intensity): 431 (M+, 68%). Anal. Calcd for C21H17N7S (431.47): C, 58.46; H, 3.97;
N, 22.72%. Found: C, 58.38; H, 3.93; N, 22.67%.
4-Phenyl-5-phenylazo-2-[2-(1,7,7-trimethylbicyclo[2.2.1]heptan-2-ylidene)-hydrazinyl]thiazole (9a). Red solid;
˝
1
yield 87%; m.p. 201–202 C (EtOH-DMF); IR: v= 3272 (NH), 1631 (C=N) cm´1; H-NMR (DMSO):
δ = 0.90–1.00 (s, 9H, 3CH3), 1.25 (m, 2H, CH2), 1.70 (m, 2H, CH2), 1.90 (m, 2H, CH2), 2.20 (m, 1H,
CH), 7.10–7.75 (m, 10H, Ar-H), 11.15 (s, 1H, NH). Anal. Calcd. for C25H27N5S (429.58): C, 69.90;
H, 6.34; N, 16.30%. Found: C, 69.81; H, 6.28; N, 16.23%.
4-Phenyl-2-[2-(1,7,7-trimethylbicyclo[2.2.1]heptan-2-ylidene)hydrazinyl]-5-(p-tolylazo)thiazole (9b). Red solid;
˝
1
yield 81%; m.p. 214–215 C (EtOH-DMF); IR: v = 3268 (NH), 1627 (C=N) cm´1; H-NMR (DMSO):
δ = 0.90–1.05 (s, 9H, 3CH3), 1.20 (m, 2H, CH2), 1.70 (m, 2H, CH2), 1.90 (m, 2H, CH2), 2.20 (m, 1H,
CH), 2.40 (s, 3H, CH3), 7.05–7.75 (m, 9H, Ar-H), 10.85 (s, 1H, NH). Anal. Calcd. for C26H29N5S
(443.61): C, 70.40; H, 6.59; N, 15.79%. Found: C, 70.30; H, 6.47; N, 15.64%.
4-Phenyl-2-[2-(1,7,7-trimethylbicyclo[2.2.1]heptan-2-ylidene)hydrazinyl]-5-(p-nitrophenylazo)thiazole (9c).
˝
Violet solid; yield 88%; m.p. 274–275 C (EtOH-DMF); IR: v = 3272 (NH), 1647 (C=N) cm´1; 1H-NMR
(DMSO): 0.90–1.05 (s, 9H, 3CH3), 1.30 (m, 2H, CH2), 1.70 (m, 2H, CH2), 1.90 (m, 2H, CH2), 2.25
(m, 1H, CH), 7.15–8.10 (m, 9H, Ar-H), 11.25 (s, 1H, NH). Anal. Calcd. for C25H26N6O2S (474.58):
C, 63.27; H, 5.52; N, 17.71%. Found: C, 63.18; H, 5.43; N, 17.67%.
3.3. Dyebath Preparation and Dyeing Procedure
The synthesized disperse dyes under investigation 7–9 series, were applied to polyester fabrics
(0.04 g dye/2 g fabric; 2% shade) by a convenient method for dyeing polyester fabrics in the
˝
laboratory at 130 C and high pressure was applied. Dyes were dispersed by dissolving the
appropriate amount of dye in acetone (1 mL) and then added dropwise with stirring to the dyebath
(liquor ration 20:1) containing an anionic dispersing agent such as 1% Setamol WS from BASF. After
adjusting THE pH of the dyebath at 5.5 using aqueous acetic acid the wetted-out polyester fibers
˝
were added. Dyeing was performed by raising the dyebath temperature from 20 to 130 C at a rate of
˝
˝
˝
3 C/min and then maintained for 60 min., followed by rapid cooling (9.9 C/min.) to 50 C. the dyed
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Molecules 2015, 20, 21982–21991
fabrics were rinsed with cold water and reduction cleared (1 g/L sodium hydroxide, 1 g/L sodium
˝
hydrosulfite, 10 min, 80 C). The samples were rinsed with hot and cold water and finally air-dried.
3.4. Dyeing Characteristics on Polyester Fabrics
3.4.1. Color Fastness Tests
The color fastness properties of the dyed fibres to washing, perspiration, rubbing, sublimation
and light were evaluated using standard methods [19]. The staining of adjacent cotton and nylon
fabrics was assessed using the grey scale: 1-poor, 2-fair, 3-moderate, 4-good and 5-excellent, other
than light fastness which scaled from 1–8 on the grey scale.
3.4.2. Color Properties of the Dyes on Polyester
˝
A reflectance spectrophotometer (GretagMacbeth CE 7000a; D65 illumination, 10 observer) was
used for the colorimetric measurements on the dyed samples. K/S values given by the reflectance
spectrometer are calculated at λ
and are directly correlated with the dye concentration on the
max
dye substrate according to the Kubelka–Munk equation K/S = (1 ´ R)2/2R, where K = absorbance
coefficient, S = scattering coefficient, R = reflectance ratio.
4. Conclusions
A set of novel 5-arylazo-2-(substituted ylidene-hydrazinyl)thiazole disperse dyes was synthesized
from novel thiazole derivatives prepared in quantitative yields by the reaction of versatile
thiosemicarbazones and phenacyl bromide using a ball-milling solid-solid reaction technique. The
newly synthesized dyes were applied as disperse dyes for dyeing polyester fabric, where they
exhibited very good dyability and fastness properties.
Acknowledgments: Technical support from Department of Chemistry, Faculty of Science, Mansoura University
and the Textile Research Division, National Research Center, Cairo, Egypt is gratefully acknowledged.
Author Contributions: H.G. and M.K. conceived, designed the experiments, performed the experiments,
analyzed the data, contributed reagents/materials/analysis tools and wrote the paper.
Conflicts of Interest: The authors declare no conflict of interest.
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Sample Availability: Samples of the compounds (7–9 series) are available from the authors.
© 2015 by the authors; licensee MDPI, Basel, Switzerland. This article is an open
access article distributed under the terms and conditions of the Creative Commons by
Attribution (CC-BY) license (http://creativecommons.org/licenses/by/4.0/).
21991