Synthesis, biological activity and dyeing performance of some novel azo disperse dyes incorporating pyrazolo[1,5-a]pyrimidines for dyeing of polyester fabrics

Article abstract of DOI:10.1016/j.molstruc.2011.11.046

Several novel pyrazolopyrimidine azo compounds were achieved from diazotization of 4-aminoacetanilide and coupling with malononitrile and then refluxed with hydrazine hydrate to furnish 3,5-diamino-4-(4-acetamidophenylazo)- 1H-pyrazole. The later compound

Full text of DOI:10.1016/j.molstruc.2011.11.046

Journal of Molecular Structure 1010 (2012) 146–151
Contents lists available at SciVerse ScienceDirect
Journal of Molecular Structure
journal homepage: www.elsevier.com/locate/molstruc
Synthesis, biological activity and dyeing performance of some novel azo
disperse dyes incorporating pyrazolo[1,5-a]pyrimidines for dyeing
of polyester fabrics
b
b
Ahmed Z. Sayed a, , Mahmoud S. Aboul-Fetouh , Hesham S. Nassar
⇑
a Chemistry Department, University College, Umm Al-Qura University, Makkah Al-Mokaramah, P.O. Box 2064, Al-Aziziah 21955, Saudi Arabia
b Chemistry Department, Faculty of Science, Al-Azhar University, Nasr City, P.O. Box 11884, Cairo, Egypt
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 12 October 2011
Received in revised form 22 November 2011
Accepted 28 November 2011
Available online 7 December 2011
Several novel pyrazolopyrimidine azo compounds were achieved from diazotization of 4-aminoacetani-
lide and coupling with malononitrile and then refluxed with hydrazine hydrate to furnish 3,5-diamino-4-
(4-acetamidophenylazo)-1H-pyrazole. The later compound was diazotized and coupled with substituted
a
-cyanocinnamate, a-cyanocinnamonitrile, 2-cyano-3-ethoxyacrylic acid ethyl ester, chalcones and
ethylacetoacetate to produce novel dyestuffs. Structures of the dyes were fully characterized by using
FT-IR, 1H NMR, mass spectroscopy and elemental analysis. The dyes were applied to polyester fiber,
affording satisfactory results and showed biological activity towards various microorganisms.
Ó 2011 Elsevier B.V. All rights reserved.
Keywords:
Pyrazolopyrimidine dyes
Disperse dyes
Dyeing properties
Polyester fabric
Biological activity
1. Introduction
exhibit significant biological activities and show ability for dyeing
of polyester fibers [8–13].
Simple nitrogen-containing heterocycles receive a large amount
of attention in the literature, as a consequence of their exciting bio-
logical properties and their role as pharmacophores of considerable
historical importance. It is well known that nitriles are widely used
as intermediates for a large number of heterocyclic compounds.
The aminopyrazole compounds have been easily obtained by the
reaction of nitrile derivatives with hydrazine, and are very useful
as precursors for the synthesis of fused heterocyclic ring systems
[1,2].
Reactions of aminopyrazoles with electrophilic reagents give
rise to various fused annulated heterocyclic systems, including
pyrazolo[1,5-a]pyrimidines which are synthetic analogs of purines.
These compounds exhibit a wide spectrum of biological activity, in
particular enzymatic, antibacterial, antiphlogistic and antiparasitic
activities [3,4]. They are also used as intermediates in the dyestuff
industry [5–7].
2. Experimental
Melting points reported were measured on a Stuart Scientific
Co. Ltd. (UK) melting point apparatus. IR spectra (KBr) were re-
corded on FTIR/5300 spectrophotometers. The absorption in the
visible region (700–325 nm) was measured by a recording Perkin
Elmer Lambda-3B UV–Visible spectrophotometer using glass cells,
having 1.0 cm optical path length. NMR spectra were measured on
DMSO-d6 solution using a Varian Mercury 300 (300 MHz 1H NMR,
75 MHz 13C NMR) spectrophotometer and chemical shifts are given
in parts per million from TMS. Mass spectra were recorded on a
GC–MS QP1000 EX (70 eV) or MS 5988 (15 eV) spectrometers. Ele-
mental analyses were carried out at the Microanalytical Centre,
Cairo University.
In the present work, some new disperse dyes from pyrazolo
[1,5-a]pyrimidine for dyeing polyester were synthesized. This is
an extension research program in our laboratory, which based on
the synthesis of novel azo-heterocyclic system. These compounds
2.1. Synthesis of the dyes
2.1.1. Synthesis of 2-(4-acetamidophenylazo)malononitrile (2)
The diazonium salt solution was prepared by adding sodium ni-
trate (0.69 g, 0.01 mol) in water (20 mL) to a solution of 4-amino-
acetanilide (1) (1.5 g, 0.01 mol) in HCl (1 M; 50 mL) at 0 °C. The
reaction mixture was stirred for 10 min. The diazotized solution
⇑
Corresponding author. Tel.: +966 0509684522.
E-mail address: ahmedzsayed@hotmail.com (A.Z. Sayed).
was then added to a well-stirred mixture of malononitrile
0022-2860/$ - see front matter Ó 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.molstruc.2011.11.046

A.Z. Sayed et al. / Journal of Molecular Structure 1010 (2012) 146–151
147
(0.66 g, 0.01 mol), ethanol (15 mL) and water (50 mL). Sodium ace-
tate was added in small portions to keep the reaction mixture alka-
line to litmus. After 3 h of stirring at 0 °C, the crude product 2 was
filtered, washed with water and air-dried as orange crystals, kmax
2.1.4. Synthesis of 2,5-diamino-3-(4-acetamidiophenylazo)-7-(substituted
phenyl)-pyrazolo[1,5-a]pyrimidine-6-carbonitrile (5a–d)
A suspension of compound 3 (2.59 g, 0.01 mol) and a-cyanocin-
namonitrile derivatives (0.01mole) in ethanol (30 mL) was refluxed
with piperidine (1 mL) for 3 h. The solid product which formed
after evaporation of the solvent was collected by filtration and
recrystallized from ethanol to give 5a–d.
481 in ethanol (log
IR (KBr)
e4.0), yield (1.77 g, 78%) and m.p. 215–217 °C.
m
max/cmꢀ1: 3545 (NH), 2984 (CH stretching), 2225 (CN),
1677 (C@O) and 1413 (N@N). 1H NMR (DMSO-d6) d ppm: 2.04
(3H, s, CH3CONH), 3.42 (1H, s, CH), 7.41–7.60 (4H, m, Ar-H),
10.01 (1H, s, CH3CONH) and 12.80 (1H, b, NH). Anal. Calcd. for
2.1.4.1. Compound 5a. This compound was obtained from reaction
of compound 3 with 2-(4-chlorobenzylidene)malononitrile (1.88 g,
C11H9N5O (227): C, 58.14; H, 3.99; N, 30.82. Found: C, 58.10; H,
4.00; N, 31.00.
0.01 mol) as yellow crystals, kmax 465 in ethanol (log
e3.8), yield
(3.21 g, 72%) and m.p. 330–331 °C. IR (KBr)
m
max/cmꢀ1: 3429,
2.1.2. Synthesis of 3,5-diamino-4-(4-acetamidiophenylazo)-1H-pyrazole
(3)
3301 (NH2, NH; broad), 2858 (CH stretching), 2213 (CN), 1605
(C@O), 1411 (N@N). 1H NMR (DMSO-d6) d ppm: 2.04 (3H, s,
CH3CO), 6.89 (2H, s, NH2), 7.55–7.98 (8H, m, Ar-H), 8.51 (2H, s,
NH2) and 10.01 (1H, s, CH3CONH). Anal. Calcd. for C21H16ClN9O
(445): C, 56.57; H, 3.62; N, 28.27. Found: C, 56.60; H, 3.60; N, 28.30.
A mixture of compound 2 (2.27 g, 0.01 mol), hydrazine hydrate
(1 mL, 0.02 mol) and pyridine 0.5 mL in 30 mL ethanol was heated
under reflux for 3 h. The reaction product was collected at room
temperature. The separated solid was filtered, washed with water,
dried and recrystallized from ethanol to give 3; as yellow crystals,
2.1.4.2. Compound 5b. This compound was obtained from reaction
kmax 452 in ethanol (log
e
3.6), yield (1.81 g, 70%) and m.p. 268–
of compound
(1.72 g, 0.01 mol) as yellow crystals, kmax 468 in ethanol (log
yield (3.13 g, 73%) and m.p. 308–309 °C. IR (KBr)
max/cmꢀ1: 3440,
3
with 2-(4-fluorobenzylidene)malononitrile
270 °C. IR (KBr)
m
max/cmꢀ1: 3395 (NH; broad) 3296, 3192 (NH2),
e
3.6),
2926 (CH stretching), 1665 (C@O), 1417 (N@N). 1H NMR (DMSO-
d6) d ppm: 2.05 (3H, s, CH3CO), 5.90 (2H, s, NH2), 6.25 (2H, s,
NH2), 7.56–7.62 (4H, m, Ar-H), 9.90 (1H, s, NH) and 10.06 (1H, s,
CH3CONH). Anal. Calcd. for C11H13N7O (259): C, 50.96; H, 5.05; N,
37.82. Found: C, 51.00; H, 5.10; N, 38.00.
m
3313, 3182 (NH2, NH; broad), 2860 (CH stretching), 2214 (CN),
1605 (C@O), 1417 (N@N). 1H NMR (DMSO-d6) d ppm: 2.05 (3H, s,
CH3CO), 7.06 (2H, s, NH2), 7.38–7.97 (8H, m, Ar-H), 8.56 (2H, s,
NH2) and 10.12 (1H, s, CH3CONH). Anal. Calcd. for C21H16FN9O
(429): C, 58.74; H, 3.76; N, 29.36. Found: C, 58.70; H, 3.80; N, 29.40.
2.1.3. Synthesis of 2-amino-3-(4-acetamidiophenylazo)-7-(substituted
phenyl)-5-oxo-4H-pyrazolo[1,5-a]pyrimidine-6-carbonitrile (4a–c)
2.1.4.3. Compound 5c. This compound was obtained from reaction
A suspension of compound 3 (2.59 g, 0.01 mol) and ethyl
a-
of compound
(1.84 g, 0.01 mol) as orange crystals, kmax 481 in ethanol (log
yield (3.49 g, 79%) and m.p. 302–304 °C. IR (KBr)
max/cmꢀ1: 3457,
3
with 2-(4-methoxybenzylidene)malononitrile
cyanocinnamate derivatives (0.01 mol) in ethanol (30 mL) was
treated with piperidine (1 mL). The reaction mixture was refluxed
for 3 h. The solvent was then evaporated and the obtained product
was recrystallized from ethanol to give 4a–c.
e
4.3),
m
3303, 3167 (NH2, NH; broad), 2835 (CH stretching), 2211 (CN),
1605 (C@O), 1414 (N@N). 1H NMR (DMSO-d6) d ppm: 2.07 (3H, s,
CH3CO), 3.81 (3H, s, OCH3), 6.51 (2H, s, NH2), 7.04–7.89 (8H, m,
Ar-H), 8.50 (2H, s, NH2) and 10.01 (1H, s, CH3CONH). Anal. Calcd.
for C22H19N9O2 (441): C, 59.86; H, 4.34; N, 28.56. Found: C,
60.00; H, 4.30; N, 29.00.
2.1.3.1. Compound 4a. This compound was obtained from reaction
of compound 3 with ethyl 3-(2-chlorophenyl)-2-cyanoacrylate
(2.59 g, 0.01 mol) as orange crystals, kmax 485 in ethanol (log
e3.2),
yield (3.37 g, 75%) and m.p. 310–312 °C. IR (KBr)
m
max/cmꢀ1: 3415,
3284, 3186 (NH2, NH), 2859 (CH stretching), 2212 (CN), 1623
(C@O), 1417 (N@N). 1H NMR (DMSO-d6) d ppm: 2.02 (3H, s,
CH3CO), 6.51 (2H, s, NH2), 7.27–7.62 (8H, m, Ar-H), 9.90 (1H, s,
NH) and 10.09 (1H, s, CH3CONH). Anal. Calcd. for C21H15ClN8O2
(447): C, 56.45; H, 3.38; N, 25.08. Found: C, 56.50; H, 3.40; N, 25.00.
2.1.4.4. Compound 5d. This compound was obtained from reaction
of compound 3 with 2-(3,4-dimethoxy-benzylidene)malononitrile
(2.14 g, 0.01 mol) as orange crystals, kmax 480 in ethanol (log
e3.1),
yield (3.49 g, 74%) and m.p. 297–299 °C. IR (KBr)
m
max/cmꢀ1: 3449,
3323 (NH2, NH; broad), 2843 (CH stretching), 2210 (CN), 1619
(C@O), 1417 (N@N). 1H NMR (DMSO-d6) d ppm: 2.03 (3H, s,
CH3CO), 3.83 (6H, s, 2xOCH3), 6.89 (2H, s, NH2), 6.94–7.62 (7H,
m, Ar-H), 8.50 (2H, s, NH2) and 10.05 (1H, s, CH3CONH). Anal. Calcd.
for C23H21N9O3 (471): C, 58.59; H, 4.49; N, 26.74. Found: C, 59.00;
H, 4.50; N, 27.00.
2.1.3.2. Compound 4b. This compound was obtained from reaction
of compound 3 with ethyl 2-cyano-3-(4-fluorophenyl)acrylate
(2.36 g, 0.01 mol) as brown crystals, kmax 491 in ethanol (log
e3.9),
yield (3.23 g, 75%) and m.p. 320–322 °C. IR (KBr)
m
max/cmꢀ1: 3408
(NH), 3286, 3189 (NH2), 2864 (CH stretching), 2218 (CN), 1624
(C@O), 1415 (N@N). 1H NMR (DMSO-d6) d ppm: 2.05 (3H, s,
CH3CO), 6.82 (2H, s, NH2), 7.43–7.82 (8H, m, Ar-H), 9.94 (1H, s,
NH) and 10.09 (1H, s, CH3CONH). Anal. Calcd. for C21H15FN8O2
(430): C, 58.60; H, 3.51; N, 26.04. Found: C, 59.00; H, 3.50; N, 26.00.
2.1.5. Synthesis of 2-amino-3-(4-acetamidiophenylazo)-5-ethoxy-7-
oxo-4H-pyrazolo[1,5-a]-pyrimidine-6-carbonitrile (6)
A mixture of compound 3 (2.59 g, 0.01 mol) and 2-cyano-3-eth-
oxyacrylic acid ethyl ester (1.69 g, 0.01 mol) was refluxing in
dimethylformamide (20 mL) and triethylamine (1 mL) for 1 h.
The reaction product was collected and recrystallized from ethanol
2.1.3.3. Compound 4c. This compound was obtained from reaction
of compound 3 with ethyl 2-cyano-3-(4-methoxyphenyl)acrylate
(2.31 g, 0.01 mol) as orange crystals, kmax 474 in ethanol (log
e
3.2),
to give 6 as brown crystals, kmax 487 in ethanol (log
e3.7), yield
yield (3.76 g, 85%) and m.p. 240–242 °C. IR (KBr)
m
max/cmꢀ1: 3423
(2.62 g, 69%) and m.p. 270–272 °C. IR (KBr)
m
max/cmꢀ1: 3439
(NH, NH2; broad), 2856 (CH stretching), 2214 (CN), 1605 (C@O),
1413 (N@N). 1H NMR (DMSO-d6) d ppm: 2.04 (3H, s, CH3CO),
3.83 (3H, s, OCH3), 6.62 (2H, s, NH2), 7.43–7.82 (8H, m, Ar-H),
9.92 (1H, s, NH) and 10.01 (1H, s, CH3CONH). Anal. Calcd. for
(NH), 3326, 3270 (NH2), 2854 (CH stretching), 2213 (CN), 1689
(C@O), 1415 (N@N). 1H NMR (DMSO-d6) d ppm: 1.21 (3H, t,
CH3CH2), 2.02 (3H, s, CH3CO), 4.02 (2H, q, CH3CH2), 6.51 (2H, s,
NH2), 7.21–7.60 (4H, d, Ar-H), 9.93 (1H, s, NH) and 10.09 (1H, s,
CH3CONH). Anal. Calcd. for C17H16N8O3 (380): C, 53.68; H, 4.24;
N, 29.46. Found: C, 54.00; H, 4.20; N, 29.50.
C22H18N8O3 (442): C, 59.72; H, 4.10; N, 25.33. Found: C, 60.00; H,
4.00; N, 25.00.

148
A.Z. Sayed et al. / Journal of Molecular Structure 1010 (2012) 146–151
2.1.6. Synthesis of 2-amino-3-(4-acetamidiophenylazo)-5-substituted-
7-substitutied-pyrazolo[1,5-a]pyrimidine (7a–c)
2.2. Dyeing procedures [14]
A mixture of compound 3 (2.59 g, 0.01 mol) and chalcones
(0.01 mol) was refluxed in piperidine (1 mL) and ethanol (30 mL)
for 4 h. The resulting product was collected by filtration and
recrystallized from acetic acid to give 7a–c.
2.2.1. Materials used
The synthesized disperse dyestuffs 2–8 used in study is shown
in Schemes 1 and 2.
Dekol-N (2 g/dm3), an anionic dispersing agent of BASF.
Levegal PT (Bayer) as carrier.
Polyester fiber; 100% (PET): Woolen type, denier 1.4 mm, from
Misr Rayon Co., Kafr El-Dawar, Egypt, which was scoured, bleached
and dried under vacuum for 48 h at room temperature.
2.1.6.1. Compounds 7a. This compound was obtained from reaction
of compound 3 with 1-(4-methoxyphenyl)-3-phenylprop-2-en-1-
one (2.38 g, 0.01 mol) as red crystals; kmax 567 in ethanol (log
e4.1),
yield (3.58 g, 80%) and m.p. 320–322 °C. IR (KBr)
m
max/cmꢀ1: 3439
2.2.2. Dyeing of polyester fiber
(NH), 3326, 3270 (NH2), 2927 (CH stretching), 1659 (C@O), 1414
(N@N). 1H NMR (DMSO-d6) d ppm: 2.07 (3H, s, CH3CO), 6.51 (2H,
s, NH2), 7.10–8.40 (14H, m, Ar-H and pyrimidine CAH) and 10.09
(1H, s, CH3CONH). Anal. Calcd for C27H23N7O2 (477): C, 67.91; H,
4.85; N, 20.53. Found: C, 68.00; H, 5.00; N, 21.00.
The required amount of dye (2% shade) was dissolved in ethanol
and added dropwise with stirring to a solution of Dekol-N (2 g/
dm3), an anionic dispersing agent of BASF, then the dye was precip-
itated in a fine dispersion ready for use in dyeing.
The dye bath (1:20 liquor ratio), containing 5 g/dm3 Levegal PT
(Bayer) as carrier, 4% ammonium sulphate, and acetic acid at pH
5.5, was brought to 60 °C, the polyester fabric was entered and
run for 15 min. The fine dispersion of the dye (2%) was added,
and the temperature was raised to boiling within 45 min, dyeing
was continued at boiling temperature for about 1 h, then the dyed
material was rinsed and soaped with 2% nonionic detergent to im-
prove rubbing and wet fastness.
2.1.6.2. Compounds 7b. This compound was obtained from reaction
of compound 3 with 3-(4-bromophenyl)-1-phenylprop-2-en-1-one
(2.87 g, 0.01 mol) as reddish-violet crystals; kmax 570 in ethanol
(loge4.5), yield (4.20 g, 80%) and m.p. 220–222 °C. IR (KBr) mmax/
cmꢀ1: 3469 (NH, NH2, broad), 2917 (CH stretching), 1654 (C@O),
1453 (N@N). 1H NMR (DMSO-d6) d ppm: 2.47 (3H, s, CH3CO),
5.34 (2H, s, NH2), 6.80–7.50 (13H, m, Ar-H and pyrimidine CAH)
and 10.09 (1H, s, CH3CONH). Anal. Calcd for C26H20BrN7O (525):
C, 59.32; H, 3.83; N, 18.63. Found: C, 69.00; H, 4.00; N, 19.00.
2.3. Assessment of color fastness [15–17]
Fastness to washing, perspiration, light, and sublimation was
tested according to the reported methods.
2.1.6.3. Compounds 7c. This compound was obtained from reaction
2.3.1. Fastness to washing
of compound
3 with 1,3-bis(4-bromophenyl)prop-2-en-1-one
A specimen of dyed polyester fabric was stitched between two
pieces of undyed cotton fabric (all fabric pieces had the same diam-
eter) and then washed at 50 °C for 30 min. The staining of the un-
dyed adjacent fabric was assessed according to the following
grayscale: 1, poor; 2, fair; 3, moderate; 4, good; 5, excellent.
(3.66 g, 0.01 mol) as reddish-violet crystals; kmax 488 in ethanol
(loge3.6), yield (4.52 g, 75%) and m.p. 308–310 °C. IR (KBr) mmax/
cmꢀ1: 3397 (NH), 3297, 3193 (NH2), 2931 (CH stretching), 1668
(C@O), 1492 (N@N). 1H NMR (DMSO-d6) d ppm: 2.04 (3H, s,
CH3CO), 6.50 (2H, s, NH2), 7.5–7.7 (13H, m, Ar-H and pyrimidine
CAH) and 10.10 (1H, s, CH3CONH). Anal. Calcd for C26H19Br2N7O
(603): C, 51.59; H, 3.16; N, 16.20. Found: C, 51.60; H, 3.20; N, 16.00.
2.3.2. Fastness to perspiration
The samples were prepared by stitching pieces of dyed polyes-
ter fabric between two pieces of undyed cotton fabric (all fabric
pieces had the same diameter) and then they were immersed in
the acid medium for 30 min. The staining of the undyed adjacent
fabric was assessed according to the following grayscale: 1, poor;
2, fair; 3, moderate; 4, good; 5, excellent. The acid solution (pH
2.1.7. Synthesis of 2-amino-3-(4-acetamidiophenylazo)-7-methyl-4H-
pyrazolo[1,5-a]-pyrimidin-5-one (8)
A solution of compound 3 (2.59 g; 0.01 mol) in acetic acid
(20 mL) was treated with ethyl acetoacetate (1.3 mL). The mixture
solution was refluxed for 3 h and the obtained product 8 was
recrystallized from ethanol as brown crystals; kmax 496 in ethanol
3.5) contained sodium chloride 10 g dmꢀ3, lactic acid 1 g dmꢀ3
disodium orthophosphate 1 g dmꢀ3, and histidine monohydrochlo-
ride 0.25 g dmꢀ3
,
.
(loge3.5), yield (2.54 g, 78% and m.p. 286–288 °C. IR (KBr) mmax/
cmꢀ1: 3443, 3283 (NH2, NH; broad), 2924 (CH stretching), 1624
(C@O), 1530 (N@N). 1H NMR (DMSO-d6) d ppm: 2.08 (3H, s,
CH3CO), 2.40 (3H, s, CH3), 5.70 (1H, s, pyrimidine CAH), 6.51 (1H,
s, pyrimidine NH), 7.61–7.82 (4H, m, Ar-H), 10.12 (1H, s,
CH3CONH) and 12.43 (2H, s, NH2). Anal. Calcd for C15H15N7O2
(325): C, 55.38; H, 4.65; N, 30.14. Found: C, 55.40; H, 5.00; N, 30.20.
2.3.3. Fastness to rubbing
The dyed polyester fabric was placed on the base of a crock me-
ter (Atlas electronic type), so that it rested flat on the abrasive cloth
with its long dimension in the direction of rubbing. A square of
white testing cloth was forced to slide on the tested fabric back
CH3COHN
N
CN
CN
NH2
N N Cl
N
CN
CN
NaNO2/HCl
N
NH2
NH
N
NH2NH2
0o
C
H2N
NHCOCH3
NHCOCH3
N
NHCOCH3
1
2
3
Scheme 1. Synthesis of 3,5-diamino-4-(4-acetamidiophenylazo)-1H-pyrazole (3) as intermediate dyes.

A.Z. Sayed et al. / Journal of Molecular Structure 1010 (2012) 146–151
149
R
O
H
N
N
N
R
O
H
N
CN
N
N
N
H2N
N
Ar
N
t
H2N
E
2
4a-c
N
O
C
C
C
CH3
N
A
A
a; Ar =C6H4Cl-2
b; Ar =C6H4F-4
c
C
C
H
8
2
C
O
H
c
; Ar =C6H4OCH3-4
2
E
t
c
r
O
H
A
CN
R
R
R
NH2
CN
Ar
N
N
N
NH2
NH
N
N
Ar`
CH
C
N
N
N
ArCOCH=CHAr`
CN
N
N
H2N
H2N
H2N
N
N
N
Ar
Ar'
5a-d
3
7a-c
a; Ar =C6H4Cl-4
b; Ar =C6H4F-4
a; Ar =C6H5,
Ar`=C6H4OCH3-4
b
; Ar = C6H4Br-4, Ar`=C6H5
c
; Ar =C6H4OCH3-4
c; Ar=Ar`=C6H4Br-4
EtO
H
CO2Et
CN
d; Ar =C6H3OCH3-3,4
C
C
R
O
H
N
N
N
CN
N
where
H2N
N
OEt
R=
H3COCHN
6
Scheme 2. Synthesis of some disperse dyestuffs (4–8).
and forth twenty times by turning the crank ten complete turns.
For the wet rubbing test, the test square was thoroughly wetted
in distilled water. The rest of the procedure was the same as the
dry test. The staining on the white testing cloth was assessed
according to the grayscale: 1, poor; 2, fair; 3, moderate; 4, good;
5, excellent.
2.4. Microbiological investigations
Antimicrobial activity was carried out by Microbiology Lab.,
Faculty of Science, Al-Azhar University, Cairo, Egypt. The antibacte-
rial activities of the synthesized compounds 2–8 were determined
by the agar diffusion technique [19]. The organisms tested were
Staphylococcus aureus (NCTC-7447) and Serratia marcesens (IMRU-
70). The antimicrobial activities of compounds 2–8 at different
concentrations (l
g/cm3) were tested to detect the minimum inhib-
2.3.4. Fastness to sublimation
Sublimation fastness was measured with an iron tester (Yasuda
No. 138). The samples were prepared by stitching pieces of dyed
polyester fabric between two pieces of undyed polyester (all fabric
pieces had the same diameter) and then treated at 180 and 210 °C
for 1 min. Any staining of the undyed adjacent fabric or change in
tone was assessed according to the following grayscale: 1, poor; 2,
fair; 3, moderate; 4, good; 5, excellent.
itory concentration (MIC) by the serial dilution method [19,20].
Most of the prepared compounds 2–8 were tested for their anti-
fungal activity using Aspergillus ochraceus Wilhelm (AUCC-230) in
Glucose-Czapek’s agar medium [21] was used for the fungi.
3. Results and discussion
3.1. Dyestuffs synthesis
2.3.5. Fastness to light
The coupling of 4-acetamidophenyldiazonium chloride with
malononitrile produced 2-(4-acetamidophenylazo)malononitrile
(2). The mass spectrum of 2 was compatible with molecular for-
mula C11H9N5O (M+ 227) and the base peak was observed at m/e
107 (100%). On the other hand, compound 2 was reacted with dif-
ferent nucleophilic reagent afforded different compounds. Thus, 2-
(4-acetamidophenylazo)malononitrile (2) and hydrazine hydrate
was refluxed in ethanol to afford the corresponding arylazo deriv-
ative 3; as shown in Scheme 1. The mass spectrum of 3 was com-
patible with molecular formula C11H13N7O (M+ 259; base beak
100%). The structure of 3 was established on the basis of elemental
analysis and spectral data.
Light fastness was determined by exposing the dyed polyester
on a Xenotest 150 (Original Hanau, chamber temperature 25–
30 °C, black panel temperature 60 °C, relative humidity 50–60%,
and dark glass (UV) filter system) for 40 h. The changes in color
were assessed according to the following blue scale: 1, poor; 3,
moderate; 5, good; 8, very good.
2.3.6. Exhaustion isotherms [18]
The rate of exhaustion of the dyestuffs on polyester fiber was
measured at equilibrium at 100 °C, according to previous methods.
The rate of exhaustion was assessed by taking samples from the
dyebath at different times during the dyeing process. The optical
density of the dye bath samples was then measured using a UV–
Visible spectrophotometer.
Reaction of 3 with ethyl
4a–c. Similarly, arylidene malononitrile, compound 3 reacted with
-cyanocinnamonitrile derivatives afforded the corresponding
a-cyanocinnamate derivatives yielded
a

150
A.Z. Sayed et al. / Journal of Molecular Structure 1010 (2012) 146–151
Table 1
Some dyeing properties for dyes 2–8 on polyester at 130 °C.
Dye
Dye take-up (%)
Washing
Perspiration
Acid
Rubbing
Dry
Sublimation fastness
Light
Alkali
Wet
Staining at 180 °C
Staining at 210 °C
(40 h)
2
3
78
79
83
85
85
82
85
87
86
83
86
86
83
82
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
3
3
4
4
4
4
4
4
4
3
4
4
4
4
4
4
6
6
6
6
6
6
6
5
6
6
6
6
4a
4b
4c
5a
5b
5c
5d
6
7a
7b
7c
8
4–5
4–5
4–5
4–5
4–5
4–5
4–5
4
4–5
4–5
4–5
4–5
4–5
4–5
4–5
4–5
4–5
4–5
4–5
4
4–5
4–5
4–5
4–5
4–5
4–5
4–5
4–5
4–5
4–5
4–5
4
4–5
4–5
4–5
4–5
pyrazolo[1,5-a]pyrimidine derivatives 5a–d. The interaction of
compound 3 with 2-cyano-3-ethoxy-acrylic acid ethyl ester by
refluxing in EtOH/Et3N via EtOH elimination afforded compound 6.
Uptake, %
The behavior of 3 towards
a,b-unsaturated ketones has also
been investigated. Thus, compound 3 reacted with chalcones in
absolute EtOH containing a catalytic amount of piperidine, under
reflux, to yield the corresponding pyrazolo[1,5-a]pyrimidine deriv-
atives (7a–c) in acceptable yield.
On the other hand, compound 3 on condensation with ethyl
acetoacetate in glacial acetic acid afforded the ketone 8; Scheme 2.
The mass spectrum of compound 8 was compatible with molecular
formula C15H15N7O2 (M+ 325; base beak 100%). The structures of all
compounds were established on the basis of elemental analysis
and spectral data.
The structures of synthesized compounds 2–8 were confirmed by
various spectroscopy techniques including IR, 1H NMR, mass and
accurate mass data. The IR spectra of 2–8 are characterized by the
ꢀ
presence of absorption bands within the
m
¼ 3395—3545 cmꢀ1 cor-
Dyeing time, (min.)
responding to the stretching vibrations of the NH and NH2 groups.
ꢀ1
ꢀ
The bands within
m
¼ 2211—2225 cm are due to the stretching
Fig. 1. Uptake of some dyes 2, 4b, 5c on polyester fiber at 2% (omf) and 130 °C.
vibration of the CN group. The absorption bands at the
ꢀ1
ꢀ
m
¼ 1605—1677 cm are due to the stretching vibration of the
ꢀ1
ꢀ
m
C@O group. The absorption bands at the
¼ 1411—1417 cm are
due to the symmetric stretching vibrations of the azo group. The
after washing are indicative of their good penetrations and excel-
lent fabric affinities due to their accumulation of polar groups;
Table 1.
1H NMR spectra showed
a characteristic NH signal in the
ꢀ
m
¼ 9:90—12:80, pyrimidine NH at 6.51 and NH2 at 5.90–6.82 ppm.
The structure of dyes 2–8 were confirmed further by mass and accu-
rate mass data. The electron impact mass spectra indicated mass
spectra indicated the presence of molecular ion peaks in all cases.
Light fastness of some dyestuffs 2–8 from compound 1 are
listed in Table 1. The light fastness results are good and acceptable
ranging ‘‘4–6’’ and showing little or no fading of light shades. The
variations in the substituent atom, and/or groups in the coupling
component have only very limited effect on fastness properties,
especially to light. Washing fastness assessment of obtained colors
on polyester fibers has shown rather good levels (4–5). The subli-
mation fastness of dyes 2–8 were in the range of 3–4, thus showed
good sublimation fastness properties on polyester fibers.
3.2. Dyeing properties of dyes
The functionalized azopyrazolo[1,5-a]pyrimidine disperse dyes
2–8 were applied to polyester fabrics at 2% shade by high-temper-
ature pressure (130 °C) and gave generally deep and bright hues,
ranging from yellow, orange to reddish-violet.
3.3. Evaluation of biological activity for synthesized dyestuffs
The visible absorption spectra of synthesized dyes 2–8 were
measured in ethanol at 1.98 ꢁ 10ꢀ5 M and their molar extinction
Some of the synthesized compounds 2–8 were evaluated for
their antimicrobial activities against some bacteria such as: S. aur-
eus, S. marcesens and also against some fungi such as A. ochraceus
Wilhelm, Table 2).
coefficients (loge) were determined. The uptake of disperse dyes
by fabrics takes place by the progressive adsorption of the small
concentration of dye in solution, which is always present in an
aqueous dispersion. The dye uptake of the dyed polyester is given
in Table 1; it can be seen that high exhaustion levels ranging from
78 to 87 were obtained; Fig. 1.
3.3.1. Antibacterial activity
The dyes 2–8 were investigated for their dyeing characteristics
on polyester and they showed good light, washing, heat and acid
perspiration fastness. The remarkable brightness of these dyes
The toxicity of these compounds mainly arises due to its unde-
sirable coordination with the metallo-enzymes and metallo-
proteins for organisms, therefore, makes inhibition for growth

A.Z. Sayed et al. / Journal of Molecular Structure 1010 (2012) 146–151
151
Table 2
Antibacterial and antifungal activity of compounds 2–8 and inhibition zones.
Compd. No.
Gram-positive
Gram-negative
Fungi
Staphylococcus aureus
Serratia marcesens
Aspergillus ochraceus
Zone
MIC
Zone
MIC
Zone
MIC
2
3
++
++
155
155
110
130
120
175
150
125
120
120
125
120
120
125
25
++
++
150
175
150
150
140
115
120
150
150
175
150
175
150
150
25
++
++
++
++
115
115
175
150
150
160
140
125
120
125
150
150
150
160
30
4a
4b
4c
5a
5b
5c
5d
6
+++
+++
++
+++
+++
++
++
+++
++
+++
+++
++
+++
+++
++
++
++
++
++
+++
+++
++
++
+++
++
+++
+++
++
7a
7b
7c
8
+++
+++
++
+++
+++
++
Control*
++++
++++
+++
+: Less active (0.2–1 cm); ++: moderate active (1–2.4 cm); +++: highly active (2.5–3.5 cm); ++++: extremely active (more than 3.5 cm).
*
Ampicillin (25 lg) and mycostatine (30 lg) were used as control for bacteria and fungi, respectively: manufactured by Bristol-Myers Squibb, Giza, Egypt.
and killing for microorganisms by the penetration into the cell
membrane, followed by destruction of cell membranes and leakage
of cell inclusion body. The results depicted in Table 2) reveal that
compounds 4a, 4b, 5a, 5b, 7b and 7c exhibited relatively high
activities against the reference Ampicillin. It is worth mentioning
that the incorporation of chloro, bromo and floro group onto the
pyrazolopyrimdine moiety caused significant activity.
In general, the tested compounds exhibit moderate to strong
activities (inhibition zones ranged from 24 to 35 mm) in compari-
son to Ampicillin (25 lg) as control ranged from 35 to 40 mm. It
showed in most cases acceptable to good fastness to light and
washing fastness on the polyester fibers and also significant anti-
microbial activity. The latter property may be beneficial to the
wearer of a garment dyed with such compounds.
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3.3.2. Antifungal activity
The results indicated that most of the tested compounds exhibit
moderate to weak actives (inhibition zones ranged from 10 to
24 mm in comparison to Mycostatine (30
from 25 to 35 mm, Table 2.
lg) as control ranged
It appears that all synthesized compounds showed those con-
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contact with human skin in some places were bacteria and fungi
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4. Conclusions
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308.
In this work, a series of azopyrazolo[1,5-a]pyrimidine dyes have
been synthesized. The characterization and the absorption ability
of 14 novel disperse dyes 2–8 were studied. The synthesized dyes
were applied successfully using high temperature dyeing to obtain
solid shades on polyester fibers with satisfactory levelness of dye-
ing and depth of shade, with observed shades of yellow, orange,
brown and reddish-violet. The results of fastness properties