The quest for environmentally friendly azo dyes of high wet fastness on polyester
is increasing in recent times (Burkinshaw, 1994). In
addition there are rising global legislative pressures to stop the use of azo
dyes that contain carcinogenic components. The heterocycles, both natural and
synthetic are known to have good biological and pharmaceutical activities. It
has even been claimed to be the first field to foster the industrial exploitation
of heteroaromatic amines (Karci, 2005).
The 4-amino-2-chloro-6,7-dimethoxyquinazolines are important synthons for the
synthesis of several biologically active molecules. For instance, a large number
of compounds possessing fused nitrogen-containing heterocyclic skeletons including
4-amino-quinazolines have been found to exhibit excellent anticancer activity
(Samieh et al., 2008; Campbell
et al., 1987; Joseph et al., 2010).
Thus, from available literatures, there is no report of the use of 4-amino-2-chloro-6,7-dimethoxyquinazoline
in the synthesis of azo disperse dye compounds.
Herein, we report the synthesis of some new 3-chloro-6, 7-dimethoxyquinazoline
azo disperse dye derivatives from 4-amino-2-chloro-6, 7-dimethoxyquinazoline.
Also, the application of the azo disperses dyes on polyester fabrics and acrylic
fabrics have been evaluated.
MATERIALS AND METHODS
Materials and apparatus: This study was conducted between 2011 and 2012
at organic chemistry research laboratory, Delta State University, Abraka, Delta
All the reagents and solvents used were of reagent-grade quality and purchased
from commercial suppliers. Melting points were determined on a Buchi SMP-20
melting point apparatus. Infrared spectra (in KBr pellets) were recorded on
Shimadu (8400), FT-IR spectrometer. 1H NMR and 13C NMR
spectra were recorded on a Mercury 200BB series spectrometer. DMSO-d6
was used as NMR solvent. Chemical shifts were reported in δ units in parts
per million (ppm) downfield from the internal standard, tetramethylsilane (TMS).
The purity of the azo compounds was monitored by Thin Layer Chromatography (TLC),
using silica gel to coated plates, F234 (Merck, aluminium sheets).
UV-Visible spectra were determined on a Genesys 10S V1.200 series spectrophotometer.
Diazotization: Compound 1, 4-amino-2-chloro-6,7-dimethoxyquinazoline (1.0
g, 2 mmoL) was pasted with NaNO2 (0.45 g, 21 mmoL) and water (10
mL) to a smooth slurry and this mixture was added to a well-stirred mixture
of HCl (d = 1.18, 4 mL) and ice (4.0 g) at 0-5°C. The reaction mixture was
stirred for 30 min to produce diazonium salt 2.
Preparation of 2-amino-5-ethylcarbazole-azo-2-chloro-6,7-dimethoxy quinazoline,
3a: Compound 3a was obtained by adding the diazonium salt solution 2 portionwise
to the coupling component, 3-amino-9-ethylcarbazole (0.9 g, 4 mmoL) dissolved
in 5 mL of acetic acid with stirring for 5 min. The reaction mixture was further
stirred for 3 h and the precipitated azo compound was isolated by filtration
and washed with water and recrystallized from ethanol to give a dark green solid
(0.76 g, 40%), M.P = 200-202°C; 1H NMR; (199.96 MHZ) DMSO-d6:
8.62 (2H, s, quinazoline-H), 7.61 (2H, s, Carbazole-H), 7.25 (1H, S, Carbazole-H),
5.45 (6H, s, OCH3), 3.92 (2H, s, CH2), 2.43 (3H, s, CH3);
13C NMR; DMSO-d6; (199.96 MHZ): 162.81, 156.22, 152.89,
149.61, 143.89, 106.29, 104.10, 104.02, 56.91, 56.82, 40.90, 40.58, 40.16, 39.75,
39.33. FT-IR (Kbr): 3694 cm-1 (v.NH), 3049 cm-1 (v C-Hstr),
1647 cm-1 (v C = CStr), 1073 cm-1 (v C-O-CStr),
791 cm-1 (v C-ClStr); UV (DMF), λmax (NM);
Preparation of 2-amino-5-methylpyrazoleazo-3-chloro-6,7-dimethoxy quinazoline,
3b: Compound 3b was obtained following a procedure similar to that used
for the formation of compound 3a, to give a yellow solid (0.95 g, 66%), M.P
= 199-201°C; 1H NMR (DMSO-d6, 199.96 MHZ) 8.65 (1H,
s, NH), 7.00-7.60 (2H, s, quinozaline-H), 5.20 (3H, s, CH3), 3.92(6H,
s, OCH3), 2.45 (2H, s, NH2), 13C NMR; (DMSO-d6;
199.96 MHZ): 162.49, 15.01, 152.22, 149.97, 142.96, 105.86, 103.33, 56.65, 56.59,
41.09, 40.08, 40.25, 39.84, 39.42, 39.01, 38.60; FT-IR (KBr): 3652 cm-1
(v NHStr), 2883 cm-1 (v C-Hstr), 1589 cm-1
(v C = CStr), 1070 cm-1 (v C-O-CStr), 860 cm-1
(v C-ClStr); UV (DMF), λmax (nm); 387.
Preparation of 2-aminopyrazoleazo-3-chloro-6,7-dimethoxy quinazoline, 3c:
Compound 3c was obtained following the procedure described for the formation
of compound 3a, thus producing a yellow solid (1.10 g, 79%), M.P = 190-192°C;
1H NMR (DMSO-d6, 199.96 MHZ) 11.79 (1H, s, NH), 8.91-9.92
(1H, s, quinozaline-H), 6.90-7.63 (2H, s, quinazoline-H), 3.91 (6H, s, OCH3),
2.45 (2H, s, NH2), 13C NMR; (DMSO-d6; 199.96
MHZ): 162.72, 156.51, 151.71, 149.800, 142.03, 105.96, 104.30, 102.88, 56.99,
56.93, 40.96, 40.54, 40.11, 39.70, 39.28; FT-IR (KBr): 3344 cm-1
(v NHStr), 3049 cm-1 (v C-Hstr), 1589 cm-1
(v C = CStr), 1064 cm-1 (v C-O-CStr), 748 cm-1
(v C-ClStr); UV-VIS (DMF), λmax (nm): 370.
Preparation of 2,4-dihydroxybenzene 3-chloro-6,7-dimethoxy quinazoline,
3d: The diazonium salt solution previously prepared was added portionwise
to the solution of 1,3-dihydroxybenzene (0.5 g, 45 mmoL) dissolved in sodium
hydroxide solution (1.0 g, 25 mmoL) in 20 mL of water with stirring for 5 min.
The reaction mixture was further stirred for 2 h and the coloured precipitate
was filtered off and recrystallized from CCl4 to give a yellow solid
(1.48 g, 98%), M.P = 198-200°C; 1H NMR (DMSO-d6, 199.96
MHZ): 8.25 (1H, s, OH), 7.60-7.80 (2H, s, quinozaline-H), 6.51-7.20 (3H, s,
ArH) 3.65-4.25 (6H, s, OCH3); 13C NMR; (DMSO-d6;
199.96 MHZ): 162.62, 155.84, 153.17, 149.28, 144.45, 106.19, 104.27, 103.76,
56.70, 56.53, 41.12, 40.69, 40.28, 39.56, 39.45, 39.02, 38.61, FT-IR (KBr):
3473 cm-1 (v OHStr), 3025 cm-1 (v C-Hstr),
1582 cm-1 (v C = CStr), 1070 cm-1 (v C-O-CStr),
769 cm-1 (v C-ClStr); UV-VIS (DMF), λmax
Preparation of 4-aminobenzonitrile azo 3-chloro-6,7-dimethoxy quinazoline,
3e: The titled Compound, 3e, was obtained following a procedure similar
to that used for obtaining compound 3a, to give a cream coloured solid (0.75
g, 49%), M.P = 218-220°C; 1H NMR (DMSO-d6, 199.96
MHZ), 8.45 (1H, s, ArH), 7.61 (2H, M, ArH), 7.01 (2H, s, OCH3), 2.45-3.81
(2H, s, NH2), 13C NMR; (DMSO-d6; 199.96 MHZ):
162.59, 155.85, 153.01, 149.28, 144.20, 106.13, 104.09, 103.74, 56.64, 56.59,
41.13, 40.71, 40.30, 39.89, 39.46, 39.05, 38.63; FT-IR (KBr): 3239 cm-1
(v NHStr), 3092 cm-1 (V C-Hstr), 1592 cm-1
(v C = Cstr), 1064 cm-1 (v C-O-CStr), 794 cm-1
(V C-ClStr); UV-VIS (DMF), λmax (nm); 459, 517.
Preparation of 2-hydroxynaphthaleneazo-3-chloro-6,7-dimethoxy quinazoline,
3f: The titled compound, 3f was obtained following a procedure similar to
that used for compound 3d, producing a brown solid (0.91 g, 55%) M.P = 210-212°C;
1H NMR; (DMSO-d6: 199.96 MHZ): 7.60-8.45 (6H, m, naphthalene-H),
6.40-7.10 (2H, s, quinozaline-H), 5.95 (1H, s, bonded OH) 3.95 (6H, s, OCH3);
13C NMR; (DMSO-d6; 199.96 MHZ): 162.81, 156.13, 153.03,
149.54, 144.13, 131.09, 130.74, 127.85, 106.32, 104.16, 104.08, 56.89, 56.78,
40.98, 40.56, 40.15, 39.73, 39.31; FT-IR (KBr): 3681 cm-1 (v OHStr),
3018 cm-1 (v C-Hstr), 1592 cm-1 (v C = CStr),
1067 cm-1 (v C-O-CStr), 739 cm-1 (v C-ClStr);
UV-VIS (DMF), λmax (nm): 516, 704.
Polyester fabric: Polyester fabric was dyed in a pressure dyeing machine
at a liquor ratio of 20:1. The dyebaths were prepared with the synthesized azo
dyes 3a-f, using Lignosulphonate as the dispersing agent. The pH of the dye
liquor was adjusted to 5 with acetic acid. Dyeing was performed and continued
for 60 min at 130°C to 135°C. The dyed polyester fabric was subjected
to reduction-cleared treatment at 85°C for 10 min in a solution of sodium
hydroxide, 2 g L-1, hydrosulphite, 2 g L-1
and then treated in a betaine amphoteric surfactant in water, washed with water
and then dried (Giles, 1974; Burkinshaw,
Acrylic fabric: The dyeing of acrylic fabrics was carried out in an
Ahiba Texomat dyeing machine at 90°C for one hour, using a 3°C min-1
temperature gradient of weight of fibre and two percent dispersing agent and
one molar equivalent of N, N-dimethylethylene diamine. The pH of dye bath was
5, adjusted using formic acid and liquor ratio of 60:1. The dyed fabrics were
removed after dyeing from the hot dyebath, soaped off, rinsed with water and
air-dried (Giles, 1974).
Wash fastness: The wash fastness of the 1% of dyeings were determined according
to ISO standard method (ISO, 1994). The composite samples
measuring (10x5 cm) were washed with soap solution (2 g L-1 Na2CO3,
5 g L-1 soap solution, liquor ratio 50:1) for 30 min at 60°C
in an Atlas Launder-O meter. The change in colour of the treated test specimens
and the degree of staining of the two adjacent undyed fabrics were evaluated
using the Grey scales.
Light fastness: The light fastness of all the dyed samples were tested
using an Atlas ES 25 Wheather-O meter (Xenon arc) according to AATCC Test Method
(AATCC, 1993). The test conditions were: Black panel
temperature: 60°C, Relative humidity: 30±5%, Chamber Temperature;
50°C, Irradiance: 0.75 W/m2, counter setting: 54 KJ/m2.
The dyed samples were exposed to these conditions and the change in colour of
the fabrics (2x6 cm) were rated against standard blue wool samples (grade 1-8):
1 (poor), 8 (excellent) (Giles, 1974; Suwanruji
et al., 2004).
Sublimation: The sublimation test was carried out according to ISO,
105-PO1 1993 test method (ISO, 1993). The dyed fabric
samples were treated in a sublimation testing machine at 177°C for 30 sec
after heat setting at 180°C for 60 sec. The tested fabrics were rated against
the Standard Grey scales (grade 1-5); 1 (poor), 5(excellent).
RESULTS AND DISCUSSION
The six azo disperse dyes were prepared by coupling of the diazotized compound
1 with heterocyclic and carbocyclic coupling components (Paula,
1995; Zollinger, 2003) (Fig. 1).
The synthesized azo compounds 3a-f are relatively high melting point colored
||Synthesis scheme for the preparation of dyes 3a-f by diazotization
of 4-amino-2-chloro-6,7-dimethoxyquinazoline and coupling with the following
amines and phenols: (i) C15H14N2, (ii)
C4H7N2, (iii) C3H5N3,
(iv) C10H8O, (v) C7H6N2,
(vi) and C6H6O2
The 3-chloro-6,7-dimethoxyquinazoline azo disperse dye derivatives were characterized
using 1H NMR, 13C NMR, IR and UV-Visible spectroscopy.
The infrared spectra of the azo compounds (in KBr) showed NH bands at 3239-3694
cm-1 region for compounds 3a, b, c and e. The FT-IR also showed broad
bands at 3473-3681 cm-1 which was assigned to OH groups for compounds
3d and f. The spectra also showed medium bands at 2883-3092 cm-1
which was assigned to aromatic C-H stretching vibrations. The bands at 1064-1070
cm-1 are indicative of the presence of C-O-C groups in the dye structure.
Also observed in the region 1582-1529 cm-1 in the IR spectra are
the presence of C = C groups in the aromatic rings. The presence of C-Cl groups
were also observed at 748-791 cm-1 region in all the compounds.
The 1H NMR spectra measured in DMSO-d6 showed an N-H
proton at δ 11.79. The various protons and their environments are also
shown. The chemical shifts of 13C NMR spectra are in accordance with
the desired synthesized products.
The electronic spectral data, showed that the azo dye compounds prepared using
carbocyclic coupling components, interestingly recorded relatively higher λmax
values than those obtained from heterocyclic coupling components; except compound
3a with a λmax of 522 nm. Thus, the other azo dye compounds
such as 3b and c showed a hyposochromic shift. This is contrary to earlier findings
that heterocyclic azo compounds show bathochromic shift than their benzenoid
analogues (Shuttleworth and Weaver, 1990; Zollinger,
2003). The azo dye compounds 3e and f showed multiplet of absorption bands
corresponding to bands at 459 to 517 nm and 516 to 704 nm, respectively. These
data are in agreement with those previously reported for similar compounds (Otutu
et al., 2011; Paula, 1995).
Fastness properties: The dyed fabrics for the fastness testings were
determined at pH 5 and were then assessed with the grey scales.
Light fastness: Table 1 shows the results of the light
fastness tests on polyester and acrylic fabrics. The results showed that the
light fastness of the dyes gave a better performance on polyester fabric (grade
5 to 5/6) than that of acrylic fabric except dyes 3a and b which gave ratings
of 4/5 on polyester fabric. The substituents on the diazo and coupling components
such as-NH2 and-OH groups ortho to the azo groups appeared to have
lowered the light fastness ratings of dyes 3a and b.
||The light and sublimation fastness of azo dyes 3a-f (1% owf)
on polyester and acrylic fabrics
||The Wash fastness of azo dyes 3a-f (1% owf) on polyester and
|Grey scale grading ranges from 1 (poor) to 5 (excellent) for
light fastness, grey scale grading ranges from 1 (poor) to 8 (excellent)
These results correlated with previous findings that electron donating groups
such as-OH and-NH2 ortho to the azo group lowers light fastness (Otutu
et al., 2011; Evans and Stapleton, 1978).
Sublimation fastness: The results of the sublimation fastness of the
dyes on polyester fabrics and acrylic fabrics is summarised in Table
1. The sublimation fastness performance of the synthesised dyes on polyester
fabrics and acrylic fabrics showed excellent ratings of 5. This is attributed
to the polar groups (Such as-OH, NH2) present in both the diazo and
coupler groups of the dye molecule (structure) (Shuttleworth
and Weaver, 1990).
Wash fastness: Table 2 shows the colour fastness of
polyester fabrics and acrylic fabrics dyed with the dyes. The results showed
good to excellent wash fastness of grade 4/5 which indicates that the dyes have
affinity for polyester fabrics and acrylic fabrics. However, the dyes have more
affinity to polyester fabrics than acrylic fabrics except dyes 3d and e where
their wash fastness ratings were the same. The higher ratings showed by the
dyes on polyester fabrics must be due to the higher crystalline structure compared
to acrylic fabrics (Karci, 2005). Table
2 also showed that there is no staining of adjacent cotton, acetate ad acrylic
fabrics, whereas staining was observed on the adjacent nylon fabrics.
Azo disperse dye derivatives of 3-chloro-6,7-dimethoxyquinazoline were synthesized
and their application on polyester and acrylic fabrics was evaluated. The azo
disperse dyes were isolated and characterized by a number of spectroscopic methods.
The results of the spectral studies of each dye were consistent and hence confirm
the predicted structures. The azo disperse dye compounds prepared from carbocyclic
coupling components showed relatively higher λmax values than
their heterocyclic coupling components which is contrary to earlier findings.
The wash fastness test results suggest that all the dyes have affinity for polyester
fibre and acryclic fibre since they gave good to excellent wet fastness grades
(ratings). At the same pH, the colour yield on acryclic fabrics was more than
that of polyester fabrics which showed higher exhaustion on acryclic fabrics
than on polyester fabrics.
The authors are grateful to Prof. Olugbade of the Obafemi Awolowo University
for the 1H NMR and 13C NMR measurements.