A facile synthesis of new monoazo disperse dyes derived from 4-hydroxyphenylazopyrazole-5-Amines: Evaluation of microwave assisted dyeing behavior

Article abstract of DOI:10.3390/molecules171213891

A series of new monoazo disperse dyes containing pyrazolopyrimidine moieties was synthesized by coupling malononitrile or 3-Aminocrotononitrile with 4-hydroxybenzenediazonium chloride. Treatment of the resulting products with hydrazine hydrate yields the corresponding 4-Arylazoaminopyrazoles, which then react with either 2,4-pentanedione and enaminonitriles or aryl-substituted enaminoketones to give the target pyrazolopyrimidine monoazo disperse dyes. Structural assignments of the dyes were made using both NMR spectroscopic and X-ray crystallographic methods. A high temperature dyeing method, by microwave irradiation, was employed with polyester fabrics. Most of the dyed fabrics tested displayed moderate light fastness and excellent washing and perspiration fastness levels.

Full text of DOI:10.3390/molecules171213891

Molecules 2012, 17, 13891-13909; doi:10.3390/molecules171213891
OPEN ACCESS
molecules
ISSN 1420-3049
www.mdpi.com/journal/molecules
Article
A Facile Synthesis of New Monoazo Disperse Dyes Derived
from 4-Hydroxyphenylazopyrazole-5-amines:
Evaluation of Microwave Assisted Dyeing Behavior
1
,
2,3
2
2
Alya M. Al-Etaibi *, Morsy A. El-Apasery , Maher R. Ibrahim and Nouria A. Al-Awadi
1
Natural Science Department, College of Health Science, Public Authority for Applied Education
and Training, P.O. Box 14281, Fayha 72853, Kuwait
2
3
Chemistry Department, Faculty of Science, Kuwait University, P.O. Box 5969, Safat 13060, Kuwait
Dyeing, Printing and Textile Auxiliaries Department, Textile Research Division,
National Research Centre, Dokki, Giza 12622, Egypt
*
Author to whom correspondence should be addressed; E-Mail: alya.aletaibi@yahoo.com.
Received: 19 October 2012; in revised form: 14 November 2012 / Accepted: 16 November 2012 /
Published: 23 November 2012
Abstract: A series of new monoazo disperse dyes containing pyrazolopyrimidine moieties
was synthesized by coupling malononitrile or 3-aminocrotononitrile with 4-hydroxy-
benzenediazonium chloride. Treatment of the resulting products with hydrazine hydrate
yields the corresponding 4-arylazoaminopyrazoles, which then react with either
2
,4-pentanedione and enaminonitriles or aryl-substituted enaminoketones to give the target
pyrazolopyrimidine monoazo disperse dyes. Structural assignments of the dyes were made
using both NMR spectroscopic and X-ray crystallographic methods. A high temperature
dyeing method, by microwave irradiation, was employed with polyester fabrics. Most of
the dyed fabrics tested displayed moderate light fastness and excellent washing and
perspiration fastness levels.
Keywords: aminopyrazoles; microwave irradiation; enaminone; disperse dyes;
2,4-pentanedione; enaminonitrile
1
. Introduction
4
-Arylazo-5-aminopyrazoles are readily obtainable, versatile compounds that have demonstrated
antibiotic properties [1–5] and are used as dyes [6,7]. While a large number of arylazopyrazole dyes

Molecules 2012, 17
13892
have been reported in the literature, very few condensed pyrazole derivatives carrying an arylazo
function on the pyrazole ring have been reported [8–13]. The present study reports the synthesis of
novel condensed 4-hydroxyphenylazopyrazolo[1,5-a]pyrimidine dyes, and their application as disperse
dyes for polyester fabrics by a method using microwave irradiation as an energy source [14,15].
2
. Results and Discussion
2.1. Synthesis
One of the sequences used for synthesis of the 4-hydroxyphenylazopyrazolo[1,5-a]pyrimidines is
coupling of malononitrile (3) with p-hydroxybenzenediazonium chloride (4) to give arylhydrazone 5
1
3
(
Scheme 1). C-NMR as well as NOE difference experiments show that this substance exists as
13
phenol 5 rather than the cyclohexadienone tautomer 6, as its C-NMR spectrum does not contain
3
resonances for a sp hybridized carbon, NOE experiments show that irradiation of the OH proton
signal at 9.63 ppm causes an enhancement of the aryl proton signal at 6.78 ppm and vice versa.
Hydrazone 5 reacts smoothly with hydrazine hydrate to yield the diaminopyrazole 7. It should be noted
that although 7 was previously prepared using the same approach, evidence for its structural
assignment was not provided in the earlier report [6].
Scheme 1. Synthesis of 4-(3,5-diamino-1H-pyrazol-4-ylazo)-phenol (7).
CN
_
N Cl
+
+
HO
N
CN
3
4
CN
CN
CN
CN
HO
NH
N
C
O
N
NH
5
6
H N NH . H O
2
2
2
HO
N N
NH2
NH
H N
2
N
7
Similarly, 3-aminocrotononitrile 8 undergoes coupling with diazonium salt 4 to yield the hydrazone
0 rather than the quinohydrazone 12, via hydrolysis of the azo-intermediate 9 (Scheme 2). The
1
possibility that 11 exists in the syn form because of the hydrogen bonding stabilization is considered
unlikely based upon previous studies that show stereoelectronic factors dominate in such systems [16].

Molecules 2012, 17
13893
Scheme 2. Synthesis of 2-[(4-hydroxyphenyl)-hydrazono]-3-oxo-butyronitrile (10).
CN
H
_
H N
+
CN
N
2
H N
2
C
C
HO
N
N Cl
+
C
C
H C
3
H C
3
N
OH
8
4
9
CH3
O
CN
CN
CN
O
H
HO
H C
3
C
C
N
N
H
N
H C
3
N
H
N
O
N
1
2
OH
OH
1
1
1
0
NOE difference experiments were done to help establish the structure of 10. The results indicate
that irradiation of the NH signal at 12.1 ppm causes an enhancement of the intensities of the aryl
proton resonances at 7.39 and 6.80 ppm. In addition, irradiating the OH signal at 9.58 ppm does not
promote any enhancement of these signals.
Reaction of hydrazone 10 with hydrazine hydrate (Scheme 3) generates the corresponding
aminopyrazole that was found to exist as a 1:1 mixture of tautomers 13A and 13B according to a
1
6
H-NMR experiment in DMSO-d solution at room temperature. NOE difference experiments show
that irradiation of the NH signal at 11.94 ppm corresponding to 13A enhances the methyl proton signal
at 2.36 ppm.
Scheme 3. Synthesis of 4-(3-amino-5-methyl-1H-pyrazol-4-ylazo)-phenol (13A) and
4
-(5-amino-3-methyl-1H-pyrazol-4-ylazo)-phenol (13B).
NH2
NH2
NH
HO
N
N
HO
N N
H N NH . H O
2
2
2
10
N
N
H
N
H C
H C
3
3
13B
13A
Pyrazoles 7 or 13 react with 2,4-pentanedione to yield 4-hydroxyphenylazopyrazolo[1,5-a]-
pyrimidines 14a and 14b, both of which exist in their phenolic forms. This conclusion is also based on
NOE difference experiments which demonstrate that irradiation of the OH signals at 9.78 and
9
.96 ppm for 14a and 14b respectively, enhances the intensities of the respective ortho aryl proton
signals 6.86 and 6.89 ppm.
Similarly, 7 or 13 react with 3-piperidinylacrylonitrile 15 to produce the corresponding
azopyrazolo[1,5-a]pyrimidines that might have either regioisomeric structure 17 or 20 (Scheme 4). The
assignment of structures 20a and 20b was made by H-C correlations observed in HMBC 2-D experiments.
5
3a
6
7
The important HMBC correlations for 20b (Figure 1) are: (a) H at 8.18 ppm with C , C and C at

Molecules 2012, 17
13894
6
5
9
1
44.3, 90.8 and 147.8 ppm, respectively; (b) H at 6.25 ppm with C at 151.5 ppm; (c) H at 7.63 ppm
8
11
10
8
11
with C and C at 146.7 and 158.6 ppm, respectively; and (d) H at 7.87 ppm with C , C
1
15
at 146.7 and 158.6 ppm, respectively. Further information came from the results of H- N HMBC
7
a
4
experiments, which show that N and N resonate at 205 and 235 ppm, respectively, this cross peak
6
7a
3
6
7a
correlations exist for the shielded proton H at 6.25 ppm with N at 205 ppm ( J) (H , N ), and that
5
4
2
5
4
the deshielded proton H at 8.18 ppm with N at 235 ppm ( J) (H , N ).
Scheme 4. Synthesis of compounds 14a,b and 20a,b.
O
O
HO
N
N
R
N
CH3
N
N
CH3
14 a, R = NH2
b, R = CH3
.
.
HO
N
N
R
NH
HO
N
N
R
N
2
NH2
CN
N
CN
N
N
N
N
1
5
16
17 a, R = NH2
7
or 13
b, R = CH3
H
H
N
HO
N
N
R
N
HO
N
N
R
N
NH
.
.
N
N
CN
NH
18
19
HO
N
N
N
N
R
N
NH2
2
0 a, R = NH2
b, R = CH3
1
13
Figure 1. H- and C-NMR resonance assignments of compound 20b.
7
.64
6
.87
H
H
H 146.7 124.1
144.3
151.5
10
9
1
58.6
8
4
N
HO
N N
H
H
9.89HO
N N
N
H8.18
3
3a
11
5
6
2.66
N
H
1
N
N7a
115.6
2
H6.25
H C
3
H C
3
N
7
122.9
14.7
NH2
NH
2
1
48.2
90.8
8
.00
1
47.8

Molecules 2012, 17
13895
Finally, the azopyrazoles 7 or 13 condense with enaminones 21a–e to yield structures which might
1
5
be formulated as either 22 or 23. N-HMBC experiments for compound 22c revealed that the
7
a
4
chemical shifts for N and N are 208.9 and 266.6 ppm, respectively, and that cross peak correlations
6
7a
3
6
7a
4
exist for coupling of the shielded proton H at 7.24 ppm with N at 208.9 ppm ( J) (H , N ) and N at
3
6
4
5
4
2
2
66.6 ppm ( J) (H , N ), and for coupling of the deshielded proton H at 8.58 ppm with only N at
2
5
4
66.6 ppm ( J) (H , N ) (Scheme 5). These observations demonstrate that the azopyrazolo[1,5-
a]pyrimidines have general structures 22.
Scheme 5. Synthesis of pyrazolo[1,5-a]pyrimidine disperse dyes 22a–j.
HO
N N
R
N
O
N
N
7
or 13 + Ar
Compound
NMe2
Ar
22a-j
Ar
a
b
c
d
e
C H
6 5
21
HO
N N
N
Ar
C H CH (p)
6
4
3
C H Cl(p)
6
4
N
Fur-2-yl
Thien-2-yl
R
N
2
3a-j
Compound
Ar
R
Compound
22
Ar
R
22
a
b
c
C H
6
5
NH2
f
C H
CH3
6
5
C H CH (p) NH2
6
4
3
g
h
i
C H CH (p) CH3
6 4 3
C H Cl(p)
NH2
NH2
NH2
6
4
C H Cl(p)
CH3
CH3
CH3
6
4
d
e
Fur-2-yl
Thien-2-yl
Fur-2-yl
Thien-2-yl
j
To confirm this conclusion, 2D NMR experiments were performed for 22c, giving the data
displayed in Figure 2, and X-ray crystallographic analysis was done for 22i (Figure 3) [17]. Selected
bond distances, angles and structure refinement in the crystal structure are given in Tables 1 and 2, the
data clearly show that the presence of N=N arylazo moiety and that the 7a-nitrogen (N31 in Figure 3)
2
has sp hybridized character.
In addition, the azo moiety has E-geometry, thus enabling hydrogen bonding interaction between a
hydrogen of the amino group (N29) and azo nitrogen (N27). Finally, the entire molecule is nearly
2
planar, indicating that all atoms comprising the basic structure are sp hybridized.
It has been reported that reaction of the diaminopyrazole 7 with benzylidenemalononitrile 24 results
in the formation of azopyrazolo[1,5-a]pyrimidines 28, whose structural assignment was made based on
the results of a previous investigation carried out by Elfahham et al. [18]. However, we observed that 7
reacts with 24 to yield the regioisomeric azopyrazolo[1,5-a]pyrimidines 30a, whose structure was
determined by using 2D NMR spectroscopic methods. Similarly the reaction of 24 with 13 afforded
the corresponding azopyrazolo[1,5-a]pyrimidine 30b (Scheme 6).

Molecules 2012, 17
Figure 2. H and C NMR resonance assignments of compound 22c.
13896
1
13
146.1
1
58.5
113.9
147.2
266.6
50.2
H
8.58 (d, J 4.4)
1
9.89
1
2
4
HO
N
N
N
H
HO 15
N
N
N
H
H
3
2
3a
5
6
1
08.4
13
115.60
.88 (d, J 8.8)
1
4
7.17
N
6
N
H
7a
122.8
NH2
N
H
NH2
N
143.7
7.24 (d, J 4.4)
7
7.72 (d, J 8.8)
1
208.9
8
62.5
151.8
H
9
129.2
2
29.5
1
31.3
.14 (d, J 8.4)
10
8
11
H
Cl
1
28.5
Cl
135.7
7.69 (d, J 8.4)
Figure 3. ORTEP plot of the x-ray crystallographic structure of 22i.
Table 1. Selected bond lengths and angles for 22i.
Bond
Bond length (Å)
1.286 (6)
1.373 (6)
1.345 (7)
1.357 (6)
1.324 (7)
1.416 (7)
1.345 (7)
1.437 (7)
Bond
Bond angle (°)
119.7 (6)
114.3 (6)
126.3 (6)
103.7 (7)
120.9 (6)
120.9 (6)
119.9(5)
N27—N28
N31—N30
N30—C40
N32—C41
N32—C42
N27—C36
N29—C40
N31—C41
N31—C44—C45
C36—N27—N28
N30—N31—C44
N31—C41—C39
C44—N31—C41
C44—N31—C41
C40—N29—H29A
C40—N29—H29B
120.1(5)

Molecules 2012, 17
Table 2. Crystal data and structure refinement for compound 22i.
13897
Chemical formula
C
16
H
12
N
6
O
2
Z
4
Formula weight
320.312
Temperature
298 K
Mo K
5804
6544
1068
0.066
0.329
0.054
0.094
0.270
433
Crystal System
Triclinic
P‐1
Radiation type
Measured reflections
Independent reflections
Observed reflections
Space group
a
b
c
8.4725 (4)Å
8.5332 (5)Å
22.111 (2)Å
97.401 (3)°
92.591 (3)°
113.776 (7)°
R
int


R(all)


R(gt)

wR(ref)
wR(all)
Parameters
3
V

1442.4 (2)Å
0.71073
Scheme 6. Synthesis of compounds 30a,b.
HO
N
N
R
N
HO
N
N
R
N
NH2
CN
NH2
CN
N
N
N
N
Ph
Ph
2
7
2
8
H
.
.
HO
N
N
NH
2
HO
N
N
R
N
NH
CN
N
CN
CN
N
R
N
CN
CN
N
Ph
Ph
7
or 13
+
25
Ph
2
6
2
4
H
N
HO
N
N
N
Ph
HO
N
N
R
Ph
N
R
N
CN
N
N
CN
NH2
NH2
30a, R = NH2
b, R = CH3
2
9
1
13
The H- and C-NMR signal assignments and H-C correlations in the HMBC 2-D experiment of
9
3
0a are displayed in Figure 4. Specific data from these measurements show that H at 9.87 ppm
5
11
10
8
correlates with C and C at 160.4 and 130.2 ppm, respectively, H at 7.57 ppm correlates with C at
1
3
12
13
15
1
37.3 ppm, H at 7.68 ppm correlates with C , C and C at 145.9, 123.0, 158.8 ppm, respectively,
1
4
12
14
15
H at 6.86 ppm correlates with C , C and C at 145.9, 115.8, 158.8 ppm, respectively, and OH at
1
4
15
9
.87 ppm correlates with C and C at 115.8 and 158.8, respectively.

Molecules 2012, 17
13898
1
13
Figure 4. H and C NMR signal assignments of 30a.
1
28.3
7.57
H
1
15.7
123.1
1
160.5
N
28.7
7.86
H
H
H
H
H
6.86H
H 7.68
9
10
1
45.5
1
16.4
N
9
.87
7.55
H
1
5
HO
N
N
N
11
HO
N
1
2
3
3a
8
4
5
1
58.8
1
4
13
2
7a
145.9
6.98H N
6
1
37.3
74.6
N
1
N
N
7
1
30.2
H N
CN
2
N
CN
2
1
15.9
1
48.9
NH2
NH
2
1
52.3
8
.50
The regioisomerism assignment of 30a was confirmed by comparison of the pyrimidine carbons of
1
3
3
0b in the C-NMR which appear at almost the same positions at δ = 160.9, 74.3, 150.4 ppm
1
5
15
15
respectively. The structure of 30b was confirmed by N-HSQC and N-HMBC. Thus, N-HSQC
1
5
1
shows the NH at δ = 87 ppm, and in N-HMBC the CH protons correlates with N at δ = 260 ppm
2
3
7
a
7a
and the NH
2
protons correlates with N at δ = 195 ppm (which is close to the N chemical shift of
2
0b and 22c).
2
.2. Dyeing and Fastness Properties
The 4-hydroxyphenylazopyrazoles 7, 13, and their pyrimidine derivatives 22a–d, and 22f–h were
explored as dyes for polyester fabrics at 1%–6% shades using the high temperature dyeing method
HT) at 130 °C for 60 min with microwave heating as the energy source. The physical and analytical
(
data for the dyed fabrics, given in Tables 3 and 4, show that use of microwave irradiation leads to a
large increase in dye uptake and dyeing rates along with enhancements in performances of dye leveling
and color homogeneity as compared by conventional method.
Table 3. Color strengths of monoazo disperse dyes on polyester fabrics.
Dye
No
7
Molecular
weight
234
Color shade on
polyester
Color strength (K/S)% Dye o.m.f.
1
2
3
4
5
6
Yellowish brown
Yellow
0.44
0.84
1.00
1.16
1.49
1.76
2
2a
2b
330
7.72
9.78
10.03
15.81
16.23
23.02
4.88
13.03
17.76
17.26
25.30
6.43
13.33
21.18
21.96
26.25
12.86
25.20
23.43
20.12
16.88
24.13
24.42
28.07
13.10
25.67
23.65
23.42
2
344
Yellow
14.59
10.72
15.44
2.18
15.72
14.92
21.08
4.35
2
2c
364
Yellow
2
2d
320
Yellowish brown
Pale brown
Yellowish orange
Orange
1
3
217
2
2f
329
22.12
20.82
14.17
23.55
20.93
16.52
24.04
21.92
17.82
24.41
22.18
19.94
2
2g
2h
343
2
363
Orange

Molecules 2012, 17
Table 4. Fastness properties of monoazo disperse dyes on polyester fabrics.
13899
Dye
o.m.f.
%
Persipiration fastness
Alkaline Acedic
a,b
Wash fastness
Light
fastness
Dye
7
Alt
5
5
SC
5
5
SW
5
5
5
5
4–5
5
5
4–5
5
5
5
5
5
4–5
5
4–5
4–5
5
5
5
Alt
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
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
SC
5
SW
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
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
Alt
5
SC
4
SW
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
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
1%
4
3–4
3
3–4
4
6
3
3
6
3–4
3–4
3
3
3
5–6
2–3
3
2
2
2a
2b
5
5
5
5
5
5
5
5
2
2c
5
5
5
5
5
2
2d
4–5
5
4–5
5
5
5
5
1
3
5
5
5
2
2f
5
5
5
5
5
2
2
2g
2h
7
5
5
5
5
5
5
5
5
5
5
2%
3%
4%
5%
5
5
5
5
4–5
5
4
5
2
2
2a
2b
5
5
5
5
5
5
5
2
2c
5
5
5
5
4–5
5
4
5
2
2d
5
4
1
3
5
5
5
5
5
2
2f
5
5
5
5
5
2
2
2g
2h
7
5
5
5
5
5
5
5
5
5
5
6
5
5
5
5
5
3–4
3–4
3–4
3
3
5
2–3
3
6
2
2
2a
2b
5
5
5
5
5
5
5
5
5
5
5
5
2
2c
5
5
5
5
5
2
2d
5
5
4–5
5
4–5
5
4–5
4–5
5
5
5
5
5
3–4
5
4–5
4–5
5
5
5
5
5
5
5
5
1
3
5
5
5
2
2f
5
5
4–5
5
5
5
5
5
2
2
2g
2h
7
5
5
5
5
5
5
5
5
5
5
5
5
3
2
2
2a
2b
5
5
5
5
5
3–4
3–4
3–4
3
5–6
2–3
3–4
6
3–4
3–4
3–4
4
5
5
5
5
5
2
2c
5
5
5
5
5
2
2d
5
5
3–4
5
4–5
5
5
5
5
5
4–5
4–5
5
1
3
2
2f
5
5
2
2
2g
2h
7
4–5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
2
2
2a
2b
5
5
5
5
5
5
5
5
5
5
2
2c
5
5
5
5
5
2
2d
4–5
5
3–4
5
3–4
5
4–5
4–5
5
5
5
5
2
1
3
5
5
5
5–6
2–3
4
2
2f
5
5
5
5
5
2
2
2g
2h
5
5
5
5
5
5
5
5
5
5
6

Molecules 2012, 17
13900
Table 4. Cont.
Dye
o.m.f.
%
Persipiration fastness
a,b
Wash fastness
Light
fastness
Dye
7
Alkaline
Acedic
Alt
5
5
SC
5
SW
5
5
Alt
5
5
SC
5
SW
5
Alt
5
SC
5
SW
5
5
6%
3
4
2
2
2a
2b
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
3–4
4
2
2c
2
1
2
2
2d
3
2f
2g
2h
4–5
5
5
5
5
4
5
5
5
4
5
4–5
5
5
5
5
4–5
5
5
4–5
5
4–5
5
5
5
4–5
5
5
5
5
5
5
5
5
4–5
5
5
5
5
5
5
2
5–6
2–3
4
2
5
5
5
5
6
a
b
ISO CO2/CO41; Alt = alteration; SC = staining on cotton; SW = staining on wool.
2
.2.1. Color Strength
The data given in Table 3 reveal that the color strengths (K/S) of the dyed polyester fabrics are
directly proportional to the amounts of the dyes applied (% o.m.f.). The hues of the fabrics treated with
the azo dyes were found to vary from yellowish-brown to orange in a manner that depends on the dye
structures. Differences in the color strengths typically depend on substitution present in the
arylazopyrazolopyrimidine disperse dyes [19–21]. The data in Table 3 clearly show that the magnitude
of color strength obtained using dye 22d is much larger than those for 22a–c and 22f–h.
2
.2.2. Wash Fastness
The polyester samples, dyed with the disperse dyes 7, 13, 22a–d, and 22f–h using the high
temperature dyeing method, were subjected to washing at 95 °C. The rates of leaching of the dyes
from the fiber in the presence of soap (or synthetic detergent) solutions of various degrees of alkalinity
are factors that determine fastness to washing. Table 4 showed that the washing fastness is excellent
with respect to most of the tested compounds except compound 22d (1%–6% shades) showed good
results. Data showed that the magnitude of dye removal depends on the molecular size of the dye
molecule, compound specific interactions between dye and substrate, wash liquor; molecular
geometry; and concentration in substrate.
2
.2.3. Light Fastness
The light fastness of each of the dyes was measured by employing the standard method for
determination of color fastness of textiles. Several reports [22–24] suggest that fading of azo dyes is
mainly a consequence of decomposition of the –N=N– moiety by either 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. Since the dyed substrate employed in this study is a
polyester fabrics (i.e., non-proteinic), the fading process likely occurs by oxidation [25]. The ease of
oxidation of azo linkages should be a function of electron density. Therefore, electron donating
substituents on this moiety should increase the fading rate while electron withdrawing groups should

Molecules 2012, 17
13901
decrease the rate. This proposal is in agreement with the observed results (Table 4) which demonstrate
that the presence of a methyl group in dyes 22b and 22g causes a decrease of light fastness to 3. On the
other hand, the chlorine atom in dyes 22c and 22h is associated with an increase of light fastness to 4
and 6, respectively.
2.2.4. Perspiration Fastness
The resistance to the action of human perspiration, referred to as the fastness to perspiration, is
evaluated by treatment of a dyed material under alkaline and acidic conditions. The results of these
tests (Table 4) using the dyed polyester indicate that the magnitude of dye removal under the influence
of perspiration is dependent upon the more polar character of the dye molecule giving lower
magnitudes of the dye removal (e.g., polyester fabrics dyed with 22h have excellent perspiration
fastness owing to the presence of the electronegative chlorine atom). In addition the results obtained
showed that dyed fabrics have good fastness to perspiration may be due to: (a) the absence of
solubilizing groups, which renders solubility, and wash ability of the dye-out of the fabrics, (b) the size
of the dye molecule is considered relatively big, (c) the good intra-fiber diffusion of the dye molecules
inside the fabrics.
3. Experimental
3.1. General
All melting points were recorded on a Gallenkamp apparatus and are uncorrected. IR spectra were
1
13
recorded in KBr disks on a Perkin Elmer System 2000 FT-IR spectrophotometer. H- and C-NMR
spectra were recorded on a Bruker DPX 400 MHz super-conducting NMR spectrometer. Mass spectra
were measured on a VG Auto-spec-Q instrument (high resolution, high performance, tri-sector 5189
GC/MS/MS) and by LC MS using an Agilent 1100 series LC/MSD with API-ES/APCI ionization
mode. Microanalyses were performed on a LECO CH NS-932 Elemental Analyzer. The microwave
oven used is a single mode cavity Explorer Microwave (CEM Corporation, Matthews, NC, USA) and
irradiate in heavy-walled Pyrex tube (capacity 10 mL and 80 mL for dyeing). The color strengths (K/S)
of the dyed polyester fabrics and the color fastness to light were evaluated at the Dyeing, Printing and
Textile Auxiliaries Department, Textile Research Division, National Research Centre (NRC), Giza,
Egypt. X-ray crystallography was carried out on a Kappa CCD Enraf Nonius FR 590 diffractometer,
National Research Centre, Giza, Egypt.
3.2. General Procedure for the Synthesis of Azo Disperse Dyes
4
-(3,5-Diamino-1H-pyrazol-4-ylazo)-phenol (7). This compound was prepared according to the
1
literature [6]. Mp 245–246 °C, H-NMR (DMSO-d
6
) δ 9.52 (s, 1H, OH), 7.52 (d, 2H, J = 8.8 Hz), 6.77
1
3
2 6
(d, 2H, J = 8.8 Hz), 6.46 (br, 1H, NH), 5.87 (br, 4H, 2NH ). C-NMR (DMSO-d ) δ 156.8, 146.4,
1
21.8, 115.5, 115.3, 115.2, 112.9. λmax (DMF)/nm 369.
2
-[(4-Hydroxyphenyl)-hydrazono]-3-oxobutyronitrile (10). p-Aminophenol (10.9 g, 0.1M) was
(7 g) in
dissolved in concentrated HCl (30 mL) and water (20 mL) cooled in ice and then NaNO
2

Molecules 2012, 17
13902
water (50 mL) was added in portions. A mixture of 3-aminocrotononitrile (8.2 g, 0.1 mole), NaOAc
20 g), ethanol (15 mL), and water (50 mL) was prepared separately and cooled in ice. The diazonium
(
salt solution was added slowly to the second solution, with ice cooling. The cooled reaction was stirred
for 0.5 h and filtered to give brown crystals, which were crystallized from alcohol/water. Brown solid
1
(
7.0 g, 85%). Mp 214–215 °C. H-NMR (DMSO-d ) δ 12.18 (s, 1H, NH), 9.61 (s, 1H, OH), 7.39
6
1
3
(
d, 1H, J = 8.8 Hz), 6.81 (d, 1H, J = 8.8 Hz), 2.37 (s, 3H, CH
3
). C-NMR (DMSO-d
6
) δ 192.6, 155.3,
1
1
34.1, 118.4, 115.9, 111.8, 111.3, 24.5. IR: 3199, 3073, 2922, 2213, 1631, 1599, 1465, 1440, 1367,
–
1
+
329, 1286, 1268, 1226, 1208, 952, 835 cm . MS (EI) m/z (%) = 203 ([M] , 100), 121 (53), 108 (93).
; calcd. 203.0689; found: 203.0689.
9 3 2
HRMS: m/z (EI) for C10H N O
4
-(3-Amino-5-methyl-1H-pyrazol-4-ylazo)-phenol (13A) and 4-(5-Amino-3-methyl-1H-pyrazol-4-
ylazo)-phenol (13B). A mixture of 10 (2.03 g, 10 mmol), hydrazine hydrate (2.5 mL) in ethanol
20 mL) was stirred at reflux for 3–4 h. The solvent was removed under vacuum and the formed solid
(
was collected and crystallized from ethanol/water. Brown solid (1.75 g, 86%). Mp 239–240 °C.
1
H-NMR (DMSO-d
6
) δ 11.94 (br, 1H, NH, 13A), 11.51 (br, 1H, NH, 13B), 9.92 (s, 2H, 2OH,
1
5
1
1
3A,13B), 7.56 (d, 4H, J = 8.4 Hz, 13A,13B), 6.81 (d, 4H, J = 8.4 Hz, 13A,13B), 6.75 (br, 2H, NH ),
2
1
3
2 3 6
.84 (br, 2H, NH ), 2.36 (s, 6H, 2CH ). C-NMR (DMSO-d ) δ 157.9, 148.2, 146.0, 140.6, 122.3,
15.5, 115.2, 18.5. λmax (DMF)/nm 376. IR: 3399, 3267, 3213, 1629, 1590, 1530, 1461, 1386, 1256,
–
1
095, 838 cm . MS (EI) m/z (%) =217 ([M]+, 100), 124 (60), 93 (12). HRMS: m/z (EI) for
O; calcd. 217.0958; found: 217.0958.
10 11 5
C H N
3.3. Synthesis of Compounds 14a–b, 20a,b and 22a–j
General procedure: a mixture of 7 (0.218 g, 1 mmol) or 13 (0.217 g, 1 mmol), acetylacetone,
-piperidinylacrylonitrile or enaminones 21a–e (1 mmol) in acetic acid (20 mL) and sod. acetate (0.12 g,
.5 mmol) was refluxed for 1 h. The reaction mixture was poured onto ice water (50 mL) filtered and
2
1
crystallized from the DMF solvent.
4
-(2-Amino-5,7-dimethyl-pyrazolo[1,5-a]pyrimidin-3-ylazo)-phenol (14a). Yellow solid (0.22 g, 77%).
1
Mp 287–288 °C. H-NMR (DMSO-d
6
) δ 9.81 (s, 1H, OH), 7.65 (dd, 2H, J = 7.2 and 1.8 Hz), 7.05 (br,
1
3
2H, NH ), 6.89 (s, 1H), 6.85 (dd, 2H, J = 7.2 and 1.8 Hz), 2.57 (s, 3H), 2.52 (s, 3H). C-NMR
2
(
DMSO-d
414, 3281, 1624, 1564, 1444, 1360, 1200, 1138, 837 cm . MS (EI) m/z (%) = 282 ([M]+, 100), 189
40), 161 (20). HRMS: m/z (EI) for C14 O; calcd. 282.1223; found: 282.1223.
6
) δ 159.7, 158.2, 151.6, 146.1, 145.9, 145.0, 122.7, 115.6, 113.7, 109.1, 24.1, 16.4. IR:
−1
3
(
14 6
H N
4
-(2,5,7-Trimethylpyrazolo[1,5-a]pyrimidin-3-ylazo)-phenol (14b). Greenish yellow solid (0.20 g,
1
6
72%). Mp > 350 °C. H-NMR (DMSO-d ) δ 9.98 (s, 1H, OH), 7.68 (dd, 2H, J = 7.2 and 1.8 Hz), 7.04
13
(
s, 1H), 6.89 (dd, 2H, J = 7.2 and 1.8 Hz), 2.70 (s, 3H), 2.66 (s, 3H), 2.59 (s, 3H). C-NMR (DMSO-d )
6
δ 161.4, 159.1, 146.8, 146.4, 145.7, 144.0, 124.5, 123.3., 115.6, 110.1, 24.4, 16.2, 15.3. IR: 3427,
−1
+
3
061, 1617, 1596, 1562, 1495, 1448, 1405, 1370, 1263, 1116, 849 cm . MS (EI) m/z (%) = 281 ([M] ,
00), 188 (90), 160 (50). HRMS: m/z (EI) for C15 O; calcd. 281.1271; found: 281.1271.
1
15 5
H N

Molecules 2012, 17
13903
4
-(2,7-Diaminopyrazolo[1,5-a]pyrimidin-3-ylazo)-phenol (20a). Reddish brown solid (0.19 g, 70%).
1
Mp 248–249 °C. H-NMR (DMSO-d ) δ 9.76 (s, 1H, OH), 8.02 (d, 1H, J = 5.6 Hz), 7.68 (br, 2H,
6
NH
2
), 7.61 (d, 2H, J = 8.8 Hz), 6.89 (br, 2H, NH
C-NMR (DMSO-d ) δ 157.8, 151.2, 149.5, 146.9, 146.7, 146.2, 122.3, 115.5, 113.8, 91.5. IR: 3456,
330, 2972, 1632, 1485, 1452, 1373, 1159, 954, 835 cm . MS (EI) m/z (%) = 269 ([M] , 100), 176
33), 148 (30). HRMS: m/z (EI) for C12 O; calcd. 269.1019; found: 269.1019.
2
), 6.84 (d, 2H, J = 8.8 Hz), 6.20 (d, 1H, J = 5.6 Hz)
1
3
6
−1
+
3
(
11 7
H N
4
-(7-Amino-2-methylpyrazolo[1,5-a]pyrimidin-3-ylazo)-phenol (20b). Brown solid (0.20 g, 75%). Mp
1
291–292 °C. H-NMR (DMSO-d ) δ 9.89 (s, 1H, OH), 8.18 (d, 1H, J = 5.4 Hz), 8.00 (br, 2H), 7.64
6
(
dd, 2H, J = 7.6 and 1.8 Hz), 6.87 (dd, 2H, J = 7.6 and 1.8 Hz), 6.25 (d, 1H, J = 5.4 Hz) 2.66 (s, 3H).
1
3
6
C-NMR (DMSO-d ) δ 158.6, 151.5, 148.2, 147.8, 146.7, 144.3, 124.1, 122.9, 115.6, 90.8, 14.7. IR:
−1
3
476, 3347, 3182, 1639, 1596, 1481, 1450, 1369, 1322, 1275, 1251, 1145, 828 cm . MS (EI)
+
m/z (%) = 268 ([M] , 100), 175 (55), 147 (40). HRMS: m/z (EI) for C H N O; calcd. 268.1067;
1
3
12
6
found: 268.1067.
4
3
2
-(2-Amino-7-phenylpyrazolo[1,5-a]pyrimidin-3-ylazo)-phenol (22a). Orange solid (0.25 g, 76%). Mp
1
01–302 °C. H-NMR (DMSO-d ) δ 9.88 (s, 1H, OH), 8.58 (d, 1H, J = 4.8 Hz), 8.08 (m, 2H,), 7.71 (d,
6
H, J = 8.8 Hz) 7.61 (m, 3H), 7.21 (d, 1H, J = 4.8 Hz), 7.14 (br, 2H, NH
2
), 6.87 (d, 2H, J = 8.8 Hz).
) δ 158.5, 151.8, 150.3, 147.3, 146.1, 144.9, 130.9, 130.5, 129.5, 128.5, 122.9,
15.6, 113.9, 108.6. λmax (DMF)/nm 385. IR: 3432, 3318, 3167, 1627, 1550, 1450, 1271, 1242, 832
1
3
C-NMR (DMSO-d
6
1
−1
+
14 6
cm . MS (EI) m/z (%) = 330 ([M] , 100), 237 (25), 115 (30). Anal. calcd. for C18H N O (330.3): C
65.44; H 4.27; N 25.44. Found: C 65.34; H 4.20; N 25.37.
4
-(2-Amino-7-p-methylphenylpyrazolo[1,5-a]pyrimidin-3-ylazo)-phenol (22b). Reddish brown solid
1
(
0.29 g, 84%). Mp 309–310 °C. H-NMR (DMSO-d
6
) δ 9.88 (s, 1H, OH), 8.54 (d, 1H, J = 4.4 Hz),
8
7
1
.02 (d, 2H, J = 8.4 Hz), 7.72 (d, 2H, J = 8.8 Hz), 7.41 (d, 2H, J = 8.4 Hz), 7.19 (d, 1H, J = 4.4 Hz),
1
3
2 6
.14 (br, 2H, NH ), 6.88 (d, 2H, J = 8.8 Hz), 2.43 (s, 3H). C-NMR (DMSO-d ) δ 158.4, 151.8, 150.1,
47.3, 146.1, 144.9, 141.1, 129.4, 129.0, 127.5, 122.8, 115.6, 113.8, 108.2, 21.1. λmax (DMF)/nm 385.
−1
IR: 3421, 3309, 2917, 1602, 1548, 1447, 1328, 1232, 1095, 833 cm . MS (EI) m/z (%) = 344
+
(
[M] , 80), 196 (30), 129 (100). HRMS: m/z (EI) for C H N O; calcd. 344.1380; found: 344.1380.
1
9
16
6
4
-(2-Amino-7-p-chlorophenylpyrazolo[1,5-a]pyrimidin-3-ylazo)-phenol (22c). Orange solid (0.28 g,
1
5
6
78%). Mp 306–307 °C. H-NMR (DMSO-d ) δ 9.89 (s, 1H, OH), 8.58 (d, 1H, H , J = 4.4 Hz), 8.14 (d,
9
13
10
6
2H, H , J = 8.4 Hz), 7.72 (d, 2H, H , J = 8.8 Hz) 7.69 (d, 2H, H , J = 8.4 Hz), 7.24 (d, 1H, H ,
1
4
13
2 6
J = 4.4 Hz), 7.17 (br, 2H, NH ), 6.88 (d, 2H, H , J = 8.8 Hz). C-NMR (DMSO-d ) δ 158.5, 151.8,
1
50.2, 147.2, 146.1, 143.7, 135.7, 131.3, 129.2, 128.5, 122.8, 115.6, 113.9, 108.4. λmax (DMF)/nm 383.
−
1
IR: 3418, 3308, 3180, 1616, 1601, 1549, 1487, 1450, 1331, 1271, 1237, 1088, 842 cm . MS (EI) m/z
+
(
%) = 364 ([M] , 100), 271 (32), 149 (42). HRMS: m/z (EI) for C18
H13ClN
6
O; calcd. 364.0833; found:
3
64.0833.
4
2
2
-(2-Amino-7-furanpyrazolo[1,5-a]pyrimidin-3-ylazo)-phenol (22d). Red solid (0.26 g, 80%). Mp
1
92–293 °C. H-NMR (DMSO-d ) δ 9.87 (s, 1H, OH), 8.55 (d, 1H, J = 5.2), 8.19 (m, 2H), 7.71 (dd,
6
2
H, J = 7.2 and 1.6), 7.43 (d, 1H J = 5.2), 7.24 (br, 2H, NH ), 6.94 (dd, 1H, J = 3.6,1.6), 6.87 (dd, 2H,

Molecules 2012, 17
13904
1
3
J 7.2 and 1.6). C-NMR (DMSO-d ) δ 158.5, 151.9, 149.3, 147.4, 146.9, 146.0, 143.0, 133.8, 122.9,
6
1
20.0, 115.6, 113.5, 113.3, 103.1. λmax (DMF)/nm 378. IR: 3449, 3411, 2923, 1595, 1449, 1316, 1009,
−1
+
8
12 6 2
24 cm . MS (EI) m/z (%) = 320 ([M] , 100), 227 (30), 116 (15). HRMS: m/z (EI) for C16H N O
calcd. 320.1016; found: 320.1016.
4
-(2-Amino-7-thiophenepyrazolo[1,5-a]pyrimidin-3-ylazo)-phenol (22e). Brown solid (0.27 g, 80%).
1
Mp 276–277 °C. H-NMR (DMSO-d ) δ 9.93 (s, 1H, OH), 8.54 (d, 1H, J = 3.6), 8.52 (d, 1H, J = 4.8),
6
8
.16 (dd, 1H, J = 4.8 and 1.2), 7.73 (m, 3H), 7.40 (dd, 1H, J = 4.8 and 1.2), 7.30 (br, 2H, NH ), 6.88
2
1
3
(d, 2H, J = 8.8). C-NMR (DMSO-d
6
) δ 158.7, 151.5, 149.2, 147.1, 145.9, 138.2, 134.9, 132.4, 129.9,
1
1
28.0, 122.8, 115.7, 113.5, 104.5. λmax (DMF)/nm 370, IR: 3437, 3107, 3023, 1602, 1549, 1500, 1450,
−1
+
414, 1330, 1242, 1183, 839 cm . MS (EI) m/z (%) = 336 ([M] , 100), 243 (50), 188 (20). Anal. calcd.
OS (336.4): C 57.13; H 3.60; N 24.98; S 9.53. Found: C 57.04; H 3.48; N 24.87; S 9.48.
12 6
for C16H N
4
-(2-Methyl-7-phenylpyrazolo[1,5-a]pyrimidin-3-ylazo)-phenol (22f). Yellow solid (0.28 g, 85%). Mp
1
297–298 °C. H-NMR (DMSO-d ) δ 10.05 (s, 1H, OH), 8.79 (d, 1H, J = 4.2 Hz), 8.11 (m, 2H), 7.73
6
(
dd, 2H, = J 8.4 and 1.8 Hz), 7.65 (m, 3H), 7.38(d, 1H, J = 4.2 Hz), 6.92 (dd, 2H, J = 8.4 and 1.8 Hz),
1
3
2
1
1
.68 (s, 3H). C-NMR (DMSO-d
6
) δ 159.5, 152.1, 147.8, 146.4, 144.7, 144.6, 136.1, 131.5, 128.8,
28.6, 125.1, 123.5, 115.7, 109.4, 14.9. λmax (DMF)/nm 372. IR: 3163, 3066, 1587, 1542, 1482, 1331,
−1
+
228, 1263, 1083, 819 cm . MS (EI) m/z (%) = 329 ([M] , 100), 236 (70), 182 (30). Anal. calcd. for
O (329.4): C 69.29; H 4.59, N 21.26. Found: C 69.27; H 4.67; N 21.25.
19 15 5
C H N
4
-(2-Methyl-7-p-methylphenylpyrazolo[1,5-a]pyrimidin-3-ylazo)-phenol (22g). Reddish brown solid
1
(0.28 g, 83%). Mp 267–268 °C. H-NMR (DMSO-d
6
) δ 10.01 (s, 1H, OH), 8.73 (d, 1H, J = 4.4 Hz),
8
6
1
.03 (d, 2H, J = 8.0 Hz), 7.70 (d, 2H, J = 8.8 Hz), 7.42 (d, 2H, J = 8.0 Hz), 7.33 (d, 1H, J = 4.4 Hz),
1
3
.89 (d, 2H, J = 8.8 Hz), 2.66 (s, 3H), 2.42 (s, 3H). C-NMR (DMSO-d
6
) δ 159.9, 152.5, 148.2, 147.0,
46.4, 145.3, 141.9, 130.1, 129.6, 127.6, 125.5, 123.9, 116.2, 109.5, 21.6, 15.5. λmax (DMF)/nm 373.
−1
+
IR: 3418, 3144, 2923, 1602, 1542, 1502, 1274, 1143, 841cm . MS (EI) m/z (%) = 343 ([M] , 100),
2
17 5
50 (53), 196 (33). HRMS: m/z (EI) for C20H N O; calcd. 343.1428; found: 343.1427.
4
8
2
-(2-Methyl-7-p-chlorophenylpyrazolo[1,5-a]pyrimidin-3-ylazo)-phenol (22h). Orange solid (0.29 g,
1
0%). Mp 259–260 °C. H-NMR (DMSO-d
6
) δ 10.06 (s, 1H, OH), 8.79 (d, 1H, J = 4.2 Hz), 8.16 (d,
1
3
H, J = 8.8 Hz), 7.72 (m, 4H), 7.4 (d, 1H, J = 4.2 Hz), 6.92 (d, 2H, J = 8.8 Hz), 2.68 (s, 3H). C-NMR
(
DMSO-d ) δ 159.4, 152.1, 147.8, 146.5, 145.9, 144.7, 131.2, 130.1, 129.6, 128.6, 125.0, 123.4, 115.7,
6
1
09.4, 14.9. λmax (DMF)/nm 373. IR: 3430, 3162, 3053, 1598, 1548, 1491, 1452, 1353, 1269, 1241,
−1
+
5
1145, 836 cm . MS (EI) m/z (%) = 363 ([M] , 100), 270 (75), 216 (30). Anal. calcd. for C19H14ClN O
(363.8): C 62.73; H 3.88, N 19.25. Found: C 62.90; H 3.87; N 19.30.
4
-(2-Methyl-7-furanepyrazolo[1,5-a]pyrimidin-3-ylazo)-phenol (22i). Red crystals were obtained from
1
DMF, (0.25 g, 78%). Mp 284–285 °C. H-NMR (DMSO-d
6
) δ 10.06 (s, 1H, OH), 8.76 (d, 1H, J = 4.8 Hz),
8
.21 (m, 2H), 7.72 (dd, 2H, J = 7.0 and 1.8 Hz), 7.56 (d, 1H, J = 4.8 Hz), 6.93 (m, 1H), 6.91 (dd, 2H, J
1
3
=
6
7.0 and 1.8 Hz), 2.76 (s, 3H). C-NMR (DMSO-d ) δ 159.5, 151.3, 148.0, 147.7, 146.5, 144.5,
1
42.7, 134.7, 124.9, 123.5, 120.4, 115.7, 113.5, 104.0, 15.1. λmax (DMF)/nm 373. IR: 3157, 3035,
−1
2
978, 1596, 1569, 1522, 1450, 1350, 1265, 1236, 1145, 1015, 842 cm . MS (EI) m/z (%) = 319

Molecules 2012, 17
13905
+
(
[M] , 100), 226 (45), 198 (30). Anal. calcd. for C H N O (319.3): C 63.94; H 4.10, N 21.93.
1
7
13
5
2
Found: C 63.93; H 4.08; N 21.78.
4
7
1
-(2-Methyl-7-thiophenepyrazolo[1,5-a]pyrimidin-3-ylazo)-phenol (22j). Reddish brown solid (0.24 g,
1
2%). Mp 278–279 °C. H-NMR (DMSO-d ) δ 10.04 (s, 1H, OH), 8.73 (d, 1H, J = 4.8 Hz), 8.57 (dd,
6
H, J = 4.2 and 1.2 Hz), 8.15 (dd, 1H, J = 4.8 and 1.2 Hz), 7.86 (d, 1H, J = 4.8 Hz), 7.72 (dd, 2H,
J = 7.2 and 1.8 Hz), 7.40 (dd, 1H, , J = 4.6 and 3.6 Hz), 6.92(dd, 2H, J = 7.2 and 1.8 Hz), 2.76 (s, 3H).
1
3
C-NMR (DMSO-d
6
) δ 159.4, 151.2, 147.7, 146.5, 144.5, 139.2, 135.3, 132.8, 129.5, 127.8, 124.9,
1
1
23.5, 115.7, 105.4, 15.1. λmax (DMF)/nm 376, IR: 3407, 3097, 2972, 1592, 1542, 1500, 1448, 1330,
−1
+
237, 1145, 1008, 843 cm . MS (EI) m/z (%) = 335 ([M] , 100), 242 (70), 188 (30). Anal. calcd. for
C H N OS (335.4): C 60.88; H 3.91, N 20.88; S 9.56. Found: C 61.01; H 3.92; N 21.01; S 9.44.
1
7
13
5
3
.4. General Procedure for the Preparation of 30a–b
A mixture of 7 (0.218 g, 1 mmol) or 13 (0.217 g, 1 mmol) in ethanol (20 mL), 5 drops of piperidine,
and benzylidenemalononitrile (0.154 g, 1 mmol) was refluxed for 6 h, then the reaction mixture was
poured into ice water, and neutralized by HCl, filtered off and recrystallized from ethanol.
2
,5-Diamino-3-(4-hydroxyphenylazo)-7-phenylpyrazolo[1,5-a]pyrimidine-6-carbonitrile (30a). Reddish
1
brown solid (0.22 g, 60%). Mp 195–196 °C. H-NMR (DMSO-d
6
) δ 9.87 (br, s, 1H, OH), 8.50 (br, 2H,
NH
2
2
), 7.86 (dd, 2H, J = 8.4 and 1.4 Hz), 7.68 (d, 2H, J = 8.8 Hz), 7.57–7.55 (m, 3H), 6.98 (br, 2H,
1
3
NH
6
), 6.86 (d, 2H, J = 8.8). C-NMR (DMSO-d ) δ 160.5, 158,8, 152.3, 148.9, 145.9, 145.5, 137.4,
1
1
30.2, 128.7, 128.3, 123.1, 116.4, 115.9, 115.7, 74.6. IR: 3429, 2919, 2850, 2213, 1624, 1471, 1367,
−1
+
130, 844 cm . MS (EI) m/z (%) = 370 ([M] , 90), 321 (100), 265 (23). HRMS: m/z (EI) for
O; calcd. 370.1285; found: 370.1285.
19 14 8
C H N
5
-Amino-3-(4-hydroxyphenylazo)-2-methyl-7-phenylpyrazolo[1,5-a]pyrimidine-6-carbonitrile (30b).
1
Yellow solid (0.23g, 63%). Mp 302–303 °C. H-NMR (DMSO-d
6
) δ 9.97 (br, s, 1H, OH), 9.00 (br,
2
H, NH ), 7.87 (dd, 2H, J = 8.4 and 1.4 Hz), 7.67(d, 2H, J = 8.4 Hz), 7.57–7.54 (m, 3H), 6.89 (d, 2H,
2
1
3
J = 8.4), 2.68 (s, 3H, CH
3
). C-NMR (DMSO-d
6
) δ 160.9, 159.5, 150.4, 148.7, 146.3, 143.9, 137.3,
1
1
30.2, 128.7, 128.3, 126.1, 123.5, 116.1, 115.7, 74.3, 15.5. IR: 3431, 3304, 3235, 3166, 2213, 1643,
−1
+
593, 1449, 1287, 1148, 842 cm . MS (EI) m/z (%) = 369 ([M] , 100), 276 (43), 222 (18). HRMS:
O; calcd. 369.1332; found: 369.1332.
15 7
m/z (EI) for C20H N
3
.5. High Temperature Dyeing Method (HT)
.5.1. Materials
Scoured and bleached 100% polyester (150, 130 g/m , 70/2 denier) was obtained from
3
2
El-Shourbagy Co., Cairo, Egypt. The fabric was treated before dyeing with a solution containing
nonionic detergent (Hostapal CV, Clariant-Egypt, 5 g/L) and sodium carbonate (2 g/L) in a ratio of
5
0:1 at 60 °C for 30 min, thoroughly washed with water, and air dried at room temperature.

Molecules 2012, 17
.5.2. Dyeing
13906
3
A dispersion of the dye was produced by dissolving the appropriate amount of dye (1%–6% shades)
3
in 1 cm acetone and then added dropwise with stirring to the dyebath (liquor ration 20:1) containing
sodium lignin sulphonate as dispersing agent. 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 under pressure in a microwave oven at a rate of 20 °C/min, holding at
this temperature for 60 min and rapidly cooling to 50 °C. After dyeing, the fabrics were thoroughly
washed and subjected to surface reduction clearing [(5 g NaOH + 6 g sodium hydrosulphite)/L]. The
samples were heated in this solution for 10 min at 60 °C and then thoroughly washed and air-dried.
3
.6. Color Measurements and Analyses
3
.6.1. Color Measurements of the Dyed Fabrics
The color yields of the dyed samples were determined by using the light reflectance technique
performed on a Perkin-Elmer (Lambda 3B) UV/VIS Spectrophotometer. The color strengths,
expressed as K/S values, were determined by applying the Kubelka-Mink equation:
2
2
K/S = [(1 − R) /2R] − [(1 − R ) /2R ]
o
o
o
where R = decimal fraction of the reflectance of the dyed fabric, R = decimal fraction of the
reflectance of the undyed fabric, K = absorption coefficient, and S = scattering coefficient.
3
3
.6.2. Color Fastness Tests
.6.2.1. Fastness to Washing
After washing using 2 g/L of the nonionic detergent Hostapal CV at 80 °C for 15 min, the dyed
fabrics were tested by using ISO standard methods [26]. A specimen of dyed polyester fabric was
stitched between two pieces of undyed cotton and wool fabrics, all of equal length, and then washed at
9
5 °C for 30 min. The staining on the undyed adjacent fabrics was assessed according to the following
gray scale: 1—poor, 2—fair, 3—moderate, 4—good, 5—excellent.
3.6.2.2. Fastness to Perspiration
The samples were prepared by stitching a piece of dyed polyester fabric between two pieces of
cotton and wool fabrics, all of equal length, and then immersed in the acid or alkaline solution
for 30 min. The staining on the undyed adjacent fabrics was assessed according to the following gray
scale: 1—poor, 2—fair, 3—moderate, 4—good, 5—excellent. The acid solution (pH = 3.5) contains
sodium chloride (10 g/L), sodium dihydrogen orthophosphate (1 g/L) and histidine monohydrochloride
(
(
0.25 g/L). The alkaline solution (pH = 8) contains sodium chloride (10 g/L), disodium orthophosphate
1 g/L) and histidine monohydrochloride (0.25 g/L).

Molecules 2012, 17
.6.2.3. Fastness to Light
Light fastness was determined by exposing the dyed polyester fabrics on a Xenotest 150 (Original
13907
3
Hanau, city, country). Chamber temperature: 25–30 °C, black panel temperature: 60 °C, relative
humidity: 50–60%, dark glass UV filter system) for 40 h. The changes in color were assessed
according to the following blue scale: 1—poor, 3—moderate, 4—good, 6—very good, 8—excellent.
4
. Conclusions
This study describes the synthesis of some new monoazo disperse pyrazolopyrimidine dyes, which
involves initial coupling of malononitrile or 3-aminocrotononitrile with 4-hydroxybenzenediazonium
chlorides, subsequent treatment of the hydrazone products with hydrazine hydrate gave the
corresponding 4-hydroxyphenylazoaminopyrazoles that were then treated with either 2,4-pentandione
or arylenaminoketones to give the target pyrazolopyrimidine monoazo disperse dyes. The dyes
produced in this manner were then applied to polyester fabrics using the HT dyeing method assisted by
microwave irradiation. The dyed fabrics, which display yellowish brown to orange hues, were found to
have moderate fastness to light and excellent fastness levels to washing and perspiration.
Acknowledgments
The support of the Public Authority for Applied Education and Training, for financing through
project (HS-08-02) and the facilities of AnaLab (SAF) at Kuwait University are gratefully
acknowledged.
References and Notes
1.
2.
3.
Ertan, N. Synthesis of some hetarylazopyrazolone dyes and solvent effects on their absorption
spectra. Dyes Pigments 1999, 44, 41–48.
Khalil, A.K.; Hassan, M.A.; Mohamed, M.M.; El-Sayed, A.M. Metal salt-catalyzed diazocoupling
of 3-substituted-1H-pyrazol-2-in-5-ones in aqueous medium. Dyes Pigments 2005, 66, 241–245.
Genin, M.J.; Biles, C.; Keiser, B.J.; Poppe, S.M.; Swaney, S.M.; Tarpley, W.G. Novel 1,5-
diphenylpyrazole nonnucleoside HIV-1 reverse transcriptase inhibitors with enhanced activity
versus the delavirdine-resistant P236L mutant: Lead identification and sar of 3- and 4-substituted
derivatives. J. Med. Chem. 2000, 43, 1034–1040.
4.
5.
6.
Kandil, S.S.; Abdel-Hay, F.I.; Issa, R.M. Thermal studies of cobalt(II), nickel(II) and copper(II)
complexes of 4-(sulfonylazido phenylazo)pyrazolones. J. Therm. Anal. Calor. 2001, 63, 173–180.
Tsai, P.C.; Wang, I.J. Synthesis and solvatochromic properties of some disazo dyes derived from
pyrazolo[1,5-a]pyrimidine derivatives. Dyes Pigments 2005, 64, 259–264.
Rangnekar, D.W.; Puro, S.S. Synthesis and dyeing characteristics of new 2-methyl-3-arylazo-6-
phenyl-7-amino- and 7-acetamidopyrazolo[1,5-a]pyrimidines. Ind. J. Fibre Textile Res. 1990, 15,
3
7–38.
Rangnekar, D.W.; Puro, S.S. Synthesis and dyeing characteristics of 3,6-bis(arylazo)pyrazolo-
1,5-a]pyrimidines. Ind. J. Fibre Textile Res. 1990, 15, 23–25.
7
.
[

Molecules 2012, 17
13908
8
.
Krystof, V.; Cankar, P.; Frysova, I.; Slouka, J.; Kontopidis, G.; Dzubak, P.; Hajduch, M.; Srovnal, J.;
de Azevedo, W.F.J.; Orsag, M.; et al. 4-Arylazo-3,5-diamino-1H- pyrazole CDK inhibitors: SAR
study, crystal structure in complex with CDK2, selectivity, and cellular effects. J. Med. Chem.
2
006, 49, 6500–6509.
9
1
1
1
.
Ho, Y.W. Synthesis of some new azo pyrazolo[1,5-a]pyrimidine-thieno[2,3-b]pyridine derivatives
and their application as disperse dyes. Dyes Pigments 2005, 64, 223–230.
0. Tsai, P.C.; Wang, I.J. Synthesis and solvatochromic properties of 3,6-bis-hetarylazo dyes derived
from pyrazolo[1,5-a]pyrimidine, Dyes Pigments 2008, 76, 575–581.
1. Karcı, F.; Demirçalı, A. Synthesis of disazo pyrazolo[1,5-a]pyrimidines. Dyes Pigments 2007, 74,
2
88–297.
2. Tsai, P.C.; Wang, I.J. A facile synthesis of some new pyrazolo[1,5-a]pyrimidine heterocyclic
disazo dyes and an evaluation of their solvatochromic behaviour. Dyes Pigments 2007, 74,
5
78–584.
1
1
1
1
3. Sayed, A.Z.; Aboul-Fetouh, M.S.; Nassar, H.S. Synthesis, biological activity and dyeing
performance of some novel azo disperse dyes incorporating pyrazolo[1,5-a]pyrimidines for
dyeing of polyester fabrics. J. Mol. Struct. 2012, 1010, 146–151.
4. Al-Etaibi, A.M.; Al-Awadi, N.A.; El-Apasery, M.A.; Ibrahim, M.R. Synthesis of some novel
pyrazolo[1,5-a]pyrimidine derivatives and their application as disperse dyes. Molecules 2011, 16,
5
182–5193.
5. Al-Etaibi, A.M.; El-Apasery, M.A.; Mahmoud, H.M.; Al-Awadi, N.A. One-pot synthesis of
disperse dyes under microwave irradiation: Dyebath reuse in dyeing of polyester fabrics.
Molecules 2012, 17, b4266–b4280.
6. El-Dusouqui, O.M.E.; Abdelkhalik, M.M.; Al-Awadi, N.A.; Dib, H.H.; George, B.J.; Elnagdi M.H.
Chemistry of 2-arylhydrazonals: Utility of substituted 2-arylhydrazono-3-oxoalkanals as
precursors for 3-oxoalkanonitriles, 3-aminoisoxazole and 1,2,3- and 1,2,4-triazoles. J. Chem. Res.
2
006, 5, 295–302.
1
1
7. CCDC 828902 contains the supplementary crystallographic data for this paper. These data can be
obtained free of charge via www.ccdc.cam.ac.uk/conts/retrieving.html (or from the CCDC, 12
Union Road, Cambridge CB2 1EZ, UK; fax: +44 1223 336033; e-mail: deposit@ccdc.cam.ac.uk).
8. Elfahham, H.A.; Elgemeie, G.E.H.; Ibraheim, Y.R.; Elnagdi, M.H. Studies on
3
,5-diaminopyrazoles: New routes for the synthesis of new pyrazoloazines and pyrazoloazoles.
Liebig. Ann. Chem. 1988, 8, 819–822.
1
2
2
2
2
9. Andrews, B.A.K.; Blanchard, E.J.; Reinhardt, R.M. Fabric whiteness retention in durable press
finishing with citric acid. Text. Chem. Color. 1993, 25, 52–54.
0. El-Kholy, Y.M.; Abdel-Hafiz, S.A.; Ahmed, S.H. Synthesis and dyeing properties of novel
disperse dyes. Part 2: Pyrazole disperse dye derivatives. J. Soc. Dyers Colour. 1998, 114, 45–48.
1. Peters, R.H.; Sumner, H.H. The affinities of vat dyes in relation to their constitutions. J. Soc.
Dyers Colour. 1955, 71, 130–138.
2. Giles, C.H.; Rahman, S.M.K. Studies on high fastness to light in coloring matters in hydrophobic
substrates. Disperse dyes in cellulose acetates and polyesters. Textile Res. J. 1961, 31, 1012–1019.
3. Shakra, S.; Ghattas, A.A.G. The effect of hydrogen bond on the light fastness of azo dyes.
Kolorisztikai Ertesito 1979, 21, 287–294.

Molecules 2012, 17
13909
2
4. Ashkar, S.M.; El-Apasery, M.A.; Touma, M.M.; Elnagdi, M.H. Synthesis of some novel
biologically active disperse dyes derived from 4-methyl-2,6-dioxo-1-propyl-1,2,5,6-
tetrahydropyridine-3-carbonitrile as coupling component and their colour assessment on polyester
fabrics. Molecules 2012, 17, 8822–8831.
2
2
5. Chipalkatti, H.R.; Desai, N.F.; Giles, C.H.; Macaulay, N. The influence of the substrate upon the
light fading of azo dyes. J. Soc. Dyers Colour. 1954, 70, 487–501.
6. Chrysler, L.P. Methods of Test for Color Fastness of Textiles and Leather, 7th ed.; Bradford:
London, UK, 1990; pp. 89–94.
Sample Availability: Samples of compounds 7, 10, 13, 14a, 14b, 20a, b, 22a–j and 30a, 30b are
available from the authors.
©
2012 by the authors; licensee MDPI, Basel, Switzerland. This article is an open access article
distributed under the terms and conditions of the Creative Commons Attribution license
http://creativecommons.org/licenses/by/3.0/).
(