Scholarly article on topic 'Synthesis and dyeing properties of some new monoazo disperse dyes derived from 2-amino-4-(2′,4′-dichlorophenyl)-1,3 thiazole'

Synthesis and dyeing properties of some new monoazo disperse dyes derived from 2-amino-4-(2′,4′-dichlorophenyl)-1,3 thiazole Academic research paper on "Chemical sciences"

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{"2-Amino-4-(2′ / 4′-dichlorophenyl)-1" / "3 Thiazole" / "Monoazo disperse dyes" / "Polyester fiber" / "Fastness properties"}

Abstract of research paper on Chemical sciences, author of scientific article — Divyesh R. Patel, Naitik B. Patel, Bhavesh M. Patel, Keshav C. Patel

Abstract Ten new monoazo disperse dyes (4a–j) have been synthesized by coupling of diazotized 2-amino-4-(2′,4′-dichlorophenyl)-1,3 thiazole (2) with various N-alkyl derivatives of substituted aniline (3a–j) and their dyeing performance on polyester fiber has been assessed. These dyes are characterized by elemental analysis, UV–vis spectra, IR and NMR spectroscopy. The absorption maxima (λ max) were recorded in DMF and were found to be in the range of 530–600nm. The dyed polyester fabric showed fair to very good light fastness and very good to excellent washing and rubbing fastness properties with superior depth and levelness.

Academic research paper on topic "Synthesis and dyeing properties of some new monoazo disperse dyes derived from 2-amino-4-(2′,4′-dichlorophenyl)-1,3 thiazole"

Journal of Saudi Chemical Society (2011) xxx, xxx-xxx

ORIGINAL ARTICLE

Synthesis and dyeing properties of some new monoazo disperse dyes derived from 2-amino-4-(2/,4/-dichlorophenyl)-1,3 thiazole

Divyesh R. Patel a *, Naitik B. Patel a, Bhavesh M. Patel b, Keshav C. Patel a

a Department of Chemistry, Veer Narmad South Gujarat University, Udhana Magdalla Road, Surat 395 007, Gujarat, India b Sir P. T. Sarvajanik College of Science, Athwalines, Surat 395 007, Gujarat, India

Received 29 August 2011; accepted 22 November 2011

KEYWORDS

2-Amino-4-(2',4'-dichloro-phenyl)-13 Thiazole; Monoazo disperse dyes; Polyester fiber; Fastness properties

Abstract Ten new monoazo disperse dyes (4a-j) have been synthesized by coupling of diazotized 2-amino-4-(2',4'-dichlorophenyl)-1,3 thiazole (2) with various N-alkyl derivatives of substituted aniline (3a-j) and their dyeing performance on polyester fiber has been assessed. These dyes are characterized by elemental analysis, UV-vis spectra, IR and NMR spectroscopy. The absorption maxima (kmax) were recorded in DMF and were found to be in the range of 530-600 nm. The dyed polyester fabric showed fair to very good light fastness and very good to excellent washing and rubbing fastness properties with superior depth and levelness.

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1. Introduction

Disperse dyes are colored organic compounds with relatively small molecular weight and having low water solubility. They are suitable for coloring hydrophobic fibers like cellulose acetate, nylon, polyester and also polypropylene and acrylic fibers

* Corresponding author. Tel.: +91 0261 2258384; fax: +91 0261 2256012.

E-mail address: divyeshpatel_905@yahoo.com (D.R. Patel).

1319-6103 © 2011 King Saud University. Production and hosting by Elsevier B.V. All rights reserved.

Peer review under responsibility of King Saud University. doi:10.1016/j.jscs.2011.11.012

from an aqueous dispersion. Very large scale of disperse dyes introduced during the last decade was used to dye polyester and the majority represent advances in application and fastness properties over dyes previously available (Dawson, 1978, 1983).

The increase of Monoazo disperse dye is due to the fact that during this time the range of shades obtainable with monoazo dyes has increased bathocromically. Today a large number of violet to blue Monoazo disperse dyes are available. So the continual research in monoazo disperse dyes is very important. Monoazo dyes with a heterocyclic system is very useful class of disperse dyes. Some very important heterocyclic diazo components such as thiazoles, isothiazoles, thiadiazoles, thio-phenes, and 4-oxoquinazolines give very good disperse dyes with excellent all round fastness properties (Weaver and Shuttleworth, 1982). Some of the heterocyclic azo dyes have excellent brightness, intensity, fastness properties, compared with their benzenoid counterparts and are commercially competitive with anthraquinone dyes. The bathochromic effect of

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the heterocyclic system was originally associated with the sulfur atom, but it is now thought that the diene character of the heterocycle is responsible for the shift (Griffiths, 1976). Dyes with aniline type coupling components containing one or more N-alkyl groups showed increased value of light and sublimation fastness (Towne et al., 1958; Weaver and Straley, 1970). Various researchers have proved the utilization of thiazole

Figure 1 General structure of disperse dyes (4a-j) Where R = Different N-alkyl derivatives of substituted aniline (3a-j) Table 1.

molecule in the synthesis of some significant disperse dyes (Peters and Gbadamosi, 1992; Bello, 1995; Hallas and Choi, 1999; Towns, 1999).

In continuation of our work toward the synthesis of disperse dyes (Patel et al., 2003), we report here the synthesis and dyeing properties of some new monoazo disperse dyes derived from the building block 2-amino 4-(2',4'-dichloro-phenyl)-1,3 thiazole moiety and its dyeing performance has been assessed on polyester fibers. The spectral characteristics, visible absorption spectra, exhaustion, fixation and fastness properties data were also reported. The general structure of the newly synthesized acid dyes is shown in Fig. 1.

2. Experimental

2.1. Material and methods

All the chemicals used in the dyes synthesis were of commercial grade and were further purified by crystallization and distillation. Melting points were determined by the open capillary

method and are uncorrected. The purity and Rf values of all the dyes were checked by Thin Layer Chromatography (Fried et al., 1982). The absorption spectra were measured using Shimadzu UV-1700 spectrophotometer at a maximum wavelength (kmax). IR spectra were recorded on Perkin-Elmer model 881 spectrophotometer using KBr pellets in the range of 4000-400 cm-1. 1H and 13C NMR spectra were recorded on Bruker Avance II 400 MHz (1H NMR) and 100 MHz (13C NMR) spectrophotometer using TMS as internal standard and DMSO as solvent. Elemental analysis of C, H and N were carried on Carlo Erba 1108 elemental analyzer instrument. The light fastness was assessed in accordance with BS: 1006-1978 (Standard test method, 1978). The rubbing fastness test was carried out with a Crockmeter (Atlas) in accordance with AATCC-1961 (AATCC test method, 1961) and the wash fastness test in accordance with IS: 765-1979 (Indian standard ISO, 1979). Particle size analysis was measured on Mastersizer S Malvern instrument.

2.2. Synthesis of 2-amino 4-(2,4'-dichlorophenyl)-1,3 thiazole (1) (Dickey et al, 1959)

In a 250 mL round bottomed flask bromine (1.60 g, 0.02 mol) was added dropwise with constant stirring to 2,4-dichloro ace-tophenone (1.89 g, 0.01 mol) and thiourea (1.52 g, 0.02 mol). The mixture was heated on the steam bath overnight and then diluted with 2.5 l of hot water (85 0C). The stirring was continued for one h under reflux condition and then filtered in hot condition. The filtrate was cooled and made slightly basic with concentrated ammonium hydroxide solution. The residue obtained was filtered, washed with hot water, dried and recrystal-lized from ethanol to give compound 1. Yield 86.2% (2.11 g).

M.p. 189-191 oc. IR (KBr, cm-1): 3455, 3395 (NH2), 1585 (C=N), 775 (C-Cl), 682 (C-S-C); *H NMR (DMSO-d6, dH ppm): 4.95 (2H, s, NH2), 7.48-7.95 (4H, m, Ar-H); 13C NMR (DMSO-d6, dC ppm): 109.12, 118.20, 120.32, 125.34, 135.40, 138.76, 140.60, 144.16, 162.43. Anal. Calcd. for C9H6Cl2N2S (245.13 g/mol): C, 44.10; H, 2.47; N, 11.43%. Found: C, 43.95; H, 2.34; N, 11.30% (Scheme 1).

2.3. General method for the preparation of diazonium salt solution (2) (Maradiya and Patel, 2001a)

Dry sodium nitrite (1.38 g, 0.02 mol) was slowly added with constant stirring to concentrated sulfuric acid (1.2 mL) on a water bath, allowing the temperature to rise to 65 0C. The solution was then cooled to 0-5 0C and a mixture of 20 mL acetic acid and propionic acid (17:3 v/v) was added dropwise with constant stirring, allowing the temperature to rise to 10-15 oc. The reaction mixture was then cooled to 0-5 oc, and 2-amino-4-(2 ,4 -dichlorophenyl)-1,3 thiazole (1) (4.90 g, 0.02 mol) was added portion wise and stirring was continued for 2 h at 0-5 oC. The excess nitrous acid was decomposed with sulfamic acid. The clear diazonium salt solution (2) thus obtained was used immediately in the next coupling reaction (Scheme 1).

2.4. Synthesis of disperse dye (4a) (Maradiya and Patel, 2002)

m-Chloro-N,N-bis(B-hydroxyethyl) aniline (4.32 g, 0.02 mole) (3a) was dissolved in methanol, and the solution was cooled to 0-5 oC. To this well stirred solution, the freshly prepared diazonium salt solution (2) was added dropwise over 45 min maintaining the temperature below 5 oC with vigorous stirring.

Where R = Different N-alkyl derivatives of substituted aniline (3a-j) (Table 1) Scheme 1 Synthesis of dye 4a using 3a as coupling component.

Stirring was continued for 1 h at 0-5 0C, maintaining pH 4-5 using sodium acetate solution (10% w/v). The dye was collected, washed several times with water until acid free and dried in an oven at 40 0C. The disperse dye was dissolved in DMF and filtered. To the filtrate, chloroform was added to precipitate pure dye. The precipitated dye (4a) was filtered and dried in an oven. The eluent system for TLC was CH3OH:H2O:AcOH (2:4:6 v/v). Dye 4a had Rf = 0.42, with minor impurities at Rf = 0.26 (Scheme 1).

Following the same coupling procedure and controlled condition, other disperse dyes 4b-jwere synthesized using the coupling components like N,N-bis-b-cyano ethyl aniline (3b), 3-(N,N-bis-b-acetoxy ethyl amino) acetanilide (3c), N-

(P-hydroxy ethyl)-N-(P-ethyl) aniline (3d), 3-(N-P-acetoxy ethyl-N-P-cyano ethyl amino) acetanilide (3e), 3-(N,N-bis-P-acetoxy ethyl amino)-4-methoxy acetanilide (3f), N-P-acetoxy ethyl-N-P-cyano ethyl-aniline (3g), N-P-cyano ethyl N-ethyl aniline (3h), m-chloro-N,N-bis-P-acetoxy ethyl aniline (3i) and 3-N,N-bis-ethyl amino acetanilide (3j) respectively. Final structures of all the dyes are shown in Table 2.

The characterization data of all the dyes are given below.

2.4.1. 2 ,2 -(3-Chloro-4-((4-(2 ,4-dichlorophenyl)thiazol-2-yl)-diazenyl)phenylazanediyl)diethanol (4a) Blue colored powder; Yield: 80.22%; M.p. 235 0C; Rf: 0.42; UV/ Vis (DMF) kmax (amax) = 600 nm (22.50 mLmg-1 cm-1); IR

Table 2 Final structures of dyes 4a-j.

(KBr, cm-1): 3495-3610 (O-H), 3012, 2940 (C-H), 1595 (N=N), 1582 (C=N), 770 (C-Cl), 685 (C-S-C); NMR (DMSO-d6, dH ppm): 3.40 (2H, s, OH), 3.85 (4H, t, CH2-O, J = 4.6 Hz), 4.35 (4H, t, CH2-N, J = 4.7 Hz), 6.98-7.95 (7H, m, Ar-H); 13C NMR (DMSO-d6, dC ppm): 42.15, 56.44, 109.12, 114.32, 118.40, 125.60, 128.12, 130.33, 134.10, 136.06, 140.10, 143.66, 145.53, 149.17, 153.75, 158.07, 167.50. Anal. Calcd. for C19H17Cl3N4O2S (471.78 g/mol): C, 48.37; H, 3.63; N, 11.88%. Found: C, 48.20; H, 3.50; N, 11.72%.

2.4.2. 3,3'-(4-((4-(2,4-Dichlorophenyl)thiazol-2-yl)diazenyl)phenylazanediyl)dipropanenitrile (4b)

Purple colored powder; Yield: 83.50%; M.p. 110 0C; Rf: 0.40; Uv/vis (DMF) kmax (amax) = 530 nm (18.70 mL mg-1 cm-1); IR (KBr, cm-1): 3035, 2955 (C-H), 2235 (C„N), 1602 (N=N), 1575 (C=N), 772 (C-Cl), 695 (C-S-C); 1H NMR (DMSO-d6, dH ppm): 3.60 (4H, t, CH2-C, J = 3.6 Hz), 4.20 (4H, t, CH2-N, J = 4.7 Hz), 6.94-8.02 (8H, m, Ar-H); 13C NMR (DMSO-d6, dC ppm): 28.14, 45.35, 108.56, 110.24, 114.79, 118.35, 126.45, 129.55, 135.29, 139.84, 142.72, 145.56, 150.43, 155.10, 159.80, 168.04. Anal. Calcd. for C21H16Cl2N6S (455.36 g/mol): C, 55.39; H, 3.54; N, 18.46%. Found: C, 55.20; H, 3.38; N, 18.33%.

2.4.3. 2,2 -(3-acetamido-4-((4-(2,4-dichlorophenyl)thiazol-2-yl)diazenyl)phenylazanediyl)bis (ethane-2,1-diyl)diacetate (4c) Violet colored powder; Yield: 78%; M.p. 260 0C; Rf: 0.38; UV/ Vis (DMF) kmax (amax) = 570 nm (20.44 mL mg-1 cm-1); IR (KBr, cm-1): 3315 (N-H), 3055, 2935 (C-H), 1682 (C=O), 1605 (N=N), 1570 (C=N), 780 (C-Cl), 680 (C-S-C); 1H NMR (DMSO-d6, dH ppm): 1.82 (3H, s, CH3), 2.35 (6H, s, CH3), 4.56 (4H, t, CH2-N, J = 4.8 Hz), 4.93 (4H, t, CH2-O, J = 4.6 Hz), 8.73 (1H, s, NH), 6.90-7.88 (7H, m, Ar-H); 13C NMR (DMSO-d6, dC ppm): 23.24, 28.06, 56.16, 68.85, 108.20, 111.80, 115.44, 118.21, 125.43, 128.33, 132.52, 136.40, 145.55, 149.20, 151.06, 154.30, 156.60, 161.30, 165.20, 166.33, 169.14. Anal. Calcd. for C^H^C^NjOsS (578.47 g/mol): C, 51.91; H, 4.36; N, 12.11%. Found: C, 51.77; H, 4.22; N, 12.01%.

2.4.4. 2-((4-((4-(2,4-Dichlorophenyl)thiazol-2-yl)diazenyl)phenyl)(ethyl)amino)ethanol (4d)

Purple colored powder; Yield: 88%, M.p. 263 0C; Rf: 0.38; UV/ Vis (DMF) kmax (amax) = 550 nm (15.00 mLmg-1 cm-1); IR (KBr, cm-1): 3480-3612 (O-H), 3050, 2968 (C-H), 1620 (N=N), 1572 (C=N), 785 (C-Cl), 671 (C-S-C); 1H NMR (DMSO-d6, dH ppm): 1.25 (3H, t, CH3, J = 4.6 Hz), 3.30 (2H, q, CH2, J = 6.2 Hz), 3.95 (2H, t, CH2, J = 3.8 Hz), 4.45 (2H, t, CH2, J = 3.8 Hz), 3.61 (1H, s, OH), 7.03-7.95 (8H, m, Ar-H); 13C NMR (DMSO-d6, dC ppm): 20.12, 55.18, 60.26, 65.75, 110.22, 114.70, 116.34, 118.40, 120.26, 125.35, 130.60, 131.55, 136.80, 138.75,140.10, 145.15, 149.44, 155.09, 166.17; Anal. Calcd. for C19H18Cl2N4OS (421.34 g/mol): C, 54.16; H, 4.31; N, 13.30%. Found: C, 54.03; H, 4.15; N, 13.18%.

2.4.5. 2-((3-acetamido-4-((4-(2,4-dichlorophenyl)thiazol-2-yl)diazenyl)phenyl)(2-cyanoethyl) amino)ethyl acetate (4e) Purple colored powder; Yield: 82%; M.p. 310 0C; Rf: 0.44; UV/Vis (DMF) kmax (amax) = 545 nm (16.75 mLmg-1 cm-1); IR (KBr, cm-1): 3325 (N-H), 3055, 2960 (C-H),

2240 (C„N), 1680 (C=O), 1615 (N=N), 1570 (C=N), 770 (C-Cl), 675 (C-S-C); 1H NMR (DMSO-d6, dH ppm): 1.95 (3H, s, CH3), 2.28 (3H, s, CH3), 3.44 (2H, t, CH2, J = 4.0 Hz), 3.78 (2H, t, CH2, J = 4.0 Hz), 4.43 (2H, t, CH2, J = 4.0 Hz), 4.82 (2H, t, CH2, J = 4.0 Hz), 8.18 (1H, s, NH), 6.82-7.88 (7H, m, Ar-H); 13C NMR (DMSO-d6, dC ppm): 20.11, 22.45, 28.15, 58.17, 60.55, 62.45, 66.70, 109.18, 111.26, 115.60, 117.35, 120.24, 126.45, 129.65, 135.25, 140.71, 145.66, 149.60, 155.15, 160.45, 165.17, 166.40, 168.15, 169.66; Anal. Calcd. for C24H22Cl2N6O3S (545.44 g/mol): C, 52.85; H, 4.07; N, 15.41%. Found: C, 52.71; H, 3.92; N, 15.17%.

2.4.6. 2,2'-(5-Acetamido-4-((4-(2,4-dichlorophenyl)thiazol-2-yl)diazenyl)-2-methoxyphenyl azanediyl)bis(ethane-2,1-diyl)diacetate (4f)

Violet colored powder; Yield: 80%; M.p. 290 0C; Rf: 0.45; UV/Vis (DMF) kmax (amax) = 578 nm (15.45 mL mg-1 cm -1); IR (KBr, cm-1): 3362 (N-H), 3028, 2954 (C-H), 1684 (C=O), 1620 (N=N), 1560 (C=N), 760 (C-Cl), 665 (C-S-C); 1H NMR (DMSO-d6, dH ppm): 1.90 (3H, s, CH3), 2.30 (6H, s, CH3), 3.75 (3H, s, OCH3), 4.10 (2H, t, CH2, J =4.2 Hz), 4.62 (2H, t, CH2, J = 4.2 Hz), 8.30 (1H, s, NH), 7.10-7.86 (6H, m, Ar-H); 13C NMR (DMSO-d6, dC ppm): 23.17, 28.70, 50.62 (OCH3), 55.36, 65.75, 110.60, 115.12, 117.66, 120.18, 122.40, 125.03, 128.09, 132.41, 135.52, 140.45, 142.56, 144.72, 149.67 156.60, 164.53,

168.45, 169.80; Anal. Calcd. for C26H27Cl2N5O6S (608.49 g/ mol): C, 51.32; H, 4.47; N, 11.51%. Found: C, 51.22; H, 4.33; N, 11.39%.

2.4.7. 2-((2-Cyanoethyl)(4-((4-(2,4-dichlorophenyl)thiazol-2-yl)diazenyl)phenyl)amino)ethyl acetate (4g)

Purple colored powder; Yield: 80%; M.p. 225 0C; Rf: 0.40; UV/ Vis (DMF) kmax (amax) = 540 nm (13.75 mLmg-1 cm-1); IR (KBr, cm-1): 3060, 2934 (C-H), 2252 (C„N), 1688 (C=O), 1626 (N=N), 1562 (C=N), 765 (C-Cl), 672 (C-S-C); 1H NMR (DMSO-d6, dH ppm): 2.26 (3H, s, CH3), 3.12 (2H, t, CH2, J = 3.6 Hz), 3.80 (2H, t, CH2, J = 3.6 Hz), 4.48 (2H, t, CH2, J = 3.6 Hz), 4.88 (2H, t, CH2, J = 3.6 Hz), 7.14-8.05 (8H, m, Ar-H); 13C NMR (DMSO-d6, dC ppm): 20.22, 23.16, 55.36, 58.45, 63.10, 110.65, 115.30, 117.42, 118.26, 120.52,

125.46, 128.32, 130.85, 132.88, 145.95, 147.46, 150.52, 155.47, 158.46, 160.68, 168.40, 170.12; Anal. Calcd. for C22H19 Cl2N5O2S (488.38 g/mol): C, 53.95; H, 3.77; N, 14.18%. Found: C, 53.95; H, 3.77; N, 14.18%.

2.4.8. 3-((4-((4-(2,4-Dichlorophenyl)thiazol-2-yl) diazenyl)phenyl)(ethyl)amino)propanenitrile (4h)

Purple colored powder; Yield: 75%; M.p. 326 0C; Rf: 0.42; UV/ Vis (DMF) kmax (amax) = 544 nm (18.62mLmg-1 cm-1); IR (KBr, cm-1): 3044, 2960 (C-H), 2241 (C„N), 1680 (C=O), 1622 (N=N), 1565 (C=N), 768 (C-Cl), 668 (C-S-C); 1H NMR (DMSO-d6, dH ppm): 1.28 (3H, t, CH3, J =7.1 Hz), 3.45 (2H, q, CH2, J = 6.2 Hz), 3.68 (2H, t, CH2, J = 3.8 Hz), 3.93 (2H, t, CH2, J = 3.8 Hz), 7.04-8.12 (8H, m, Ar-H); 13C NMR (DMSO-d6, dC ppm): 20.06, 23.16, 45.35, 52.48, 109.80, 111.46, 114.30, 117.26, 118.25, 120.55,123.82, 125.75, 127.65, 129.51, 135.09, 139.78, 145.62, 147.50, 155.20, 166.30; Anal. Calcd. for C20H17Cl2N5S (430.35 g/mol): C, 55.82; H, 3.98; N, 16.27%. Found: C, 55.66; H, 3.80; N, 16.11%.

Table 3 Particle size analysis of dyes 4a-j.

Dye no. Obscurationa (%) Particle size (im) at different diameter D Span

D (v, 0.1) D (v, 0.5) D (v, 0.9)

4a 21.1 0.22 0.33 0.65 1.3030

4b 18.9 0.28 0.35 0.72 1.2571

4c 18.5 0.20 0.40 0.76 1.4000

4d 19.6 0.33 0.38 0.80 1.2368

4e 19.0 0.25 0.42 0.68 1.0230

4f 19.4 0.21 0.45 0.70 1.0890

4g 18.8 0.23 0.40 0.66 1.0750

4h 19.3 0.24 0.41 0.73 1.1951

4i 19.6 0.27 0.36 0.76 1.3611

4j 20.0 0.26 0.37 0.79 1.4324

D (v, 0.5) is the diameter where 50% of the distribution is above and 50% is below. D (v, 0.9) is the diameter where 90% of the volume distribution is below this value. D (v, 0.1) is the diameter where 10% of the volume distribution is below this value. a The light intensity absorbed by the sample.

13CMalvern Mastersizer... fl O S3 2:14 PM

Figure 2 Particle size analysis of dye 4a.

2.4.9. 2,2'-(3-Chloro-4-((4-(2,4-dichlorophenyl)thiazol-2-yl)diazenyl)phenylazanediyl)bis (ethane-2,1-diyl) diacetate (4i) Violet colored powder; Yield: 77%; M.p. 252 0C; Rf: 0.40; UV/ Vis (DMF) kmax (amax) = 565 nm (20.25 mL mg-1 cm-1); IR (KBr, cm-1): 3038, 2956 (C-H), 1685 (C=O), 1620 (N=N), 1568 (C=N), 760 (C-Cl), 683 (C-S-C); 1H NMR (DMSO-d6, dH ppm): 2.25 (6H, s, CH3), 4.20 (4H, t, CH2, J = 3.8 Hz), 4.74 (4H, t, CH2, J = 3.8 Hz), 7.06-8.10 (7H, m, Ar-H); 13C NMR (DMSO-d6, dC ppm): 23.18, 54.26, 62.44, 108.04, 110.56, 113.93, 115.35, 120.33, 123.65, 129.56, 131.67, 134.60, 137.78, 139.90, 145.84, 149.70, 151.40, 166.36, 169.75; Anal. Calcd. for C23H21Cl3N4O4S (555.86 g/mol): C, 49.70; H, 3.81; N, 10.08%. Found: C, 49.59; H, 3.66; N, 09.90%.

2.4.10. N-(2-((4-(2,4-Dichlorophenyl)thiazol-2-yl)diazenyl)-5-(diethylamino)phenyl)acetamide (4j)

Purple colored powder; Yield: 80%; M.p. 301 0C; Rf: 0.38; UV/ Vis (DMF) kmax (amax) = 535 nm (17.50 mLmg-1 cm-1); IR (KBr, cm-1): 3338 (N-H), 3018, 2940 (C-H), 1675 (C=O), 1618 (N=N), 1568 (C=N), 785 (C-Cl), 672 (C-S-C); 1H NMR (DMSO-d6, dH ppm): 1.32 (6H, t, CH3, J =7.1 Hz),

2.15 (3H, s, CH3), 3.66 (4H, q, CH2, J = 6.8 Hz), 8.10 (1H, s, NH), 6.97-7.95 (7H, m, Ar-H); 13C NMR (DMSO-d6, dC ppm): 23.65, 28.45, 55.15, 108.06, 110.95, 112.20, 114.64, 118.32, 122.31, 124.56, 130.50, 133.61, 135.24, 138.45, 140.55, 145.56,155.15,166.24,169.95; Anal. Calcd. for C21H21Cl2N5OS (462.39 g/mol): C, 54.55; H, 4.58; N, 15.15%. Found: C, 54.36; H, 4.42; N, 15.03%.

2.5. Particle size analysis

All the dyes were milled with glass beads and water to reduce the particle size of dyes samples. The particle size analysis of dyes samples was measured by using laser diffraction method which contains He-Ne laser of wavelength 632.8 nm. Distilled water is taken as medium for analysis and the stirrer regulator should be set at 2000 rpm.

The particle size of all the dyes was in the range of 0.200.80 im. The span is the width of the distribution based on the 10%, 50% and 90% distribution and it is calculated by the following equation Eq. (1).

Figure 3 Particle size analysis of dye 4f.

D(v, 0.9)- D(v, 0.2)

D(v, 0.5) ( )

Smaller size of dye particles would readily accelerate the penetration of dye particle in to the fiber which resulted in more efficient fixation. The small particle size also results in better solubility and hence the unfixed dyes are easily washed

off from the fiber which makes excellent wash fastness properties. After particle size analysis the dye suspension is sieved by a nylon sieve and then dried and further used in the dyeing process.

Particle size analysis data is shown in Table 3 and figures of dyes 4a and 4f are shown in Figs. 2 and 3.

2.6. Application of disperse dyes to polyester fabric

Application of disperse dyes to polyester fabric was carried out by the following high temperature high pressure (HTHP) procedure (Maradiya and Patel, 2001b). Preparation of dye bath. Dyeing procedure (HTHP method).

2.6.1. Materials and conditions for 2% (owf) shade

2.6.2. Preparation of dye bath

A paste of weighted quantity of dye under study (40 mg) was prepared with dispersing agent Dodamol (100 mg), Wetting agent Tween-80 (5 mg) and water (1 mL). To this paste water (99 mL) was added with stirring. The pH was adjusted to pH 4.5-5.0 using acetic acid.

2.6.3. Dyeing procedure

A convenient laboratory method for dyeing polyester fiber is to employ high temperature (130-135 0C) and high pressure (25-30 psi), using a laboratory HTHP dyeing machine with a glycerin bath. Dye solution (100 mL) was added to a beaker provided with a lid and screwed up. Before closing the lid and tightening the metal cap over the beaker, wetted pattern of polyester was rolled properly and dropped into the beaker. The beaker was then placed vertically on the rotatory carrier inside the tank and the clamp plate was firmly tightened by the nut of the stud. The rotatory carrier was allowed to rotate in glycerin bath, the temperature of which was raised at a rate of 2 0C per minute up to a final temperature of 120 0C. The temperature was maintained at 120 0C by the automatic device. The whitening was continued for 60 min at 120 0C under pressure. After cooling over a period of 1 h, the beaker was removed from the bath and washed with water. The pattern was washed with cold water several times.

2.6.4. Reduction clears of the dyed fabric

Dyed polyester fabrics were then reduction cleared by stirring in a solution containing 2 g/L of sodium dithionite, 2 g/L of sodium hydroxide and 1 g/L of sodium hydrosulphite for 15 min at 65-70 0C. The polyester fibers were then rinsed with hot and cold water and then acidified with 1 mL/L glacial acetic acid solution. The polyester fabrics were then rinsed with cold water and further treated with solution of detergent (Lissapol D) by soaping process. After soaping process the polyester fibers were rinsed with water and dried.

Machine used for dyeing The Glycerin Bath (HTHP

beaker dyeing machine)

Weight of the polyester fabric 2.0 g

Amount of the dye under study 40 mg

Dispersing agent (Dodamol) 100 mg

Wetting agent Tween-80 5 mg

MLR 1:50

Total volume of the solution 100 mL

pH of the dye bath 4.5-5.0 with glacial acetic acid

Temperature of the dyebath 130 0C

Pressure of the dyebath 25-30 psi

3. Results and discussion

3.1. Spectral characteristics

The structures of all disperse dyes (4a-j) were confirmed by various spectroscopic techniques including IR, and 13C NMR.

The IR spectra (Colthup et al., 1991) of dyes 4a and 4d showed a broad band at 3480-3612 cm-1 due to the O-H stretching vibration of hydroxyl group. Dyes 4c, 4e, 4f and 4jshowed medium band at 3315-3362 cm-1 due to the N-H stretching vibration of secondary amino group. All the dyes 4a-jshowed two characteristic bands at 3012-3060 cm-1 and 2934-2968 cm-1 due to the C-H stretching vibration of methyl and methylene group. Dyes 4b, 4e, 4g and 4h showed a band at 2235-2251 cm-1 due to the C„N stretching vibration of cya-no group. The carbonyl group of dyes 4c, 4e, 4f, 4g and 4i showed C=O stretching vibration at 1675-1688 cm-1. All the dyes 4a-jshowed a medium band at 1595-1626 cm-1 due

Concentration (10-3) ml/min

Figure 7 Calibration curve for exhaustion study of disperse dyes.

4 6 8 10 12 Concentration (10-3) mg/ml

Figure 8 Calibration curve for fixation study of disperse dyes.

° а Jß ß

"Ö Ö

и Сц

iö тЗ

-О -Ö

un CN а\ ^о un un

^ о тЗ и

to the N=N stretching vibration of azo group. The thiazole ring was confirmed by the band at 665-695 cm-1. The chloro group was confirmed by the presence of a band at 760785 cm-1. (IR spectra of dye 4a is shown in Fig. 4)

The 1H NMR spectra (Bassler et al., 1991) of dyes 4a and 4d showed a singlet at 3.40-3.61 d ppm due to the OH proton. Dyes 4a, 4c, 4e, 4f, 4g and 4i showed a triplet at 3.854.93 d ppm due to the CH2-O proton while dyes 4a-c, 4e, 4f, 4g-i showed a triplet at 4.10-4.56 d ppm due to the CH2-N proton. Dyes 4d and 4jshowed quartet at 3.30-3.66 d ppm due to the CH2 proton coupled with CH3 group. Dyes 4c, 4e, 4f, 4g, 4i and 4jshowed a singlet at 1.62-2.26 d ppm due to the CH3 proton of acetyl and acetamido groups and dyes 4d, 4h and 4jshowed a triplet at 1.25-1.32 d ppm due to the CH3 proton of terminal ethyl group. (1H NMR spectra of dye 4a is shown in Fig. 5)

The 13C NMR spectra (Bassler et al., 1991) of dye 4f showed a band at 50.65 d ppm due to the OCH3 carbon. The CH3 carbon of acetyl and acetamido group of dyes 4c, 4e, 4f, 4g, 4i and 4jshowed bands at 20.11-28.70 d ppm. The carbon of C„N group of dyes 4b, 4e, 4g and 4h showed a band at 117.35-119.25 d ppm. The carbonyl carbon of acetyl and acetamido groups of dyes 4c, 4e, 4f, 4g, 4i and 4jshowed bands at 169.14-170.12 d ppm. The CH2 carbon of dyes 4a-e showed bands at 42.15-68.85 d ppm. The aromatic carbon showed bands at 108.04-168.45 d ppm. (13C NMR spectra of dye 4a is shown in Fig. 6)

3.2. UV-vis spectra (Yadav, 2005)

The data of absorption spectra (kmax) of all the dyes (4a-j) were recorded in DMF and were found in the range of 530600 nm. The kmax values depend on the nature and position of the substituent at the terminal amino group as well as on the phenyl ring. The value of absorptivity (amax) was calculated by the Lambert-Beer's law Eq. (2) and calibration curve. The values of absorptivity (extinction coefficient) were in the range of 13.75-22.50 mL mg-1 cm-1.

A = acl (2)

A = Absorbance

a = Absorptivity (extinction coefficient), c = Concentration (mg/mL) and l = Path length (cm)

The introduction of acetyl group in dye 4i (kmax = 565 nm) resulted in hypsochromic shift of 35 nm in the kmax value of dye 4a (kmax = 600 nm). The introduction of chloro group in dye 4i (kmax = 565 nm) in place of acetamido group showed hypsochromic shift of 5 nm in the kmax of dye 4c (kmax = 570 nm). The replacement of hydroxyl group in dye 4d (kmax = 550 nm) by cyano group resulted in hypsochromic shift of 5 nm in kmax of dye 4g (kmax = 540 nm). The introduction of acetamido group in dye 4g (kmax = 540 nm) showed batho-chromic shift of 5 nm in the kmax of dye 4e (kmax = 545 nm) also the bathochromic shift of 7 nm was observed in dye 4f (kmax = 578 nm) by the introduction of methoxy group in dye 4c (kmax = 570 nm).

3.3. Exhaustion and fixation study

The data of exhaustion and fixation percentage were calculated by the earlier described calibration curve process (Patel and Patel, 2005). The calibration curve data of exhaustion and fixation of dyes are shown in Figs. 7 and 8 and the data are summarized in Table 4. Exhaustion and fixation data of all the dyes are shown in Table 5.

The percentage exhaustion on polyester fabric ranges from 70.00-81.30%, in which dye 4i showed maximum value while dye 4c showed minimum value. The percentage fixation on polyester fabric ranges from 83.33-90.42%, in which dye 4a showed maximum value and dye 4d showed minimum value.

3.4. Study of light, wash and rubbing fastness properties 3.4.1. Light fastness

It is common practice to study light fastness properties of dyed patterns by automatic devices known as fadometers. Xeno test machine is a much better instrument for this purpose. For the

Table 5 Exhaustion, fixation and fastness properties data of dyes 4a-j on polyester fabric.

Substrate for dyeing Dyed pattern for fixation study Amount of dye under study Medium of spectral study

Polyester (2.0 g) Polyester (0.1 g) 40 mg

DMF for exhaustion study and Conc. H2SO4 for fixation study

Dye no. % Exhaustion % Fixation Light fastness Wash fastness Rubbing fastness

Alteration Staining Dry Wet

4a 74.60 90.42 4-5 4 4 4 4

4b 79.78 90.38 4 4 4-5 4-5 4

4c 70.00 87.14 6 4-5 5 4 5

4d 71.40 83.33 4-5 4 4-5 4 4

4e 73.60 84.05 6 5 4 4 5

4f 80.30 88.78 6 4 4 5 4

4g 77.18 87.46 4 4 4 4 4

4h 72.63 89.00 5 4 4-5 4 4

4i 81.30 90.02 4-5 4 4 5 5

4j 75.35 88.25 6 5 4 4 4

Light fastness: 8-Maximum, 7-Excellent, 6-Very good, 5-Good, 4-Fair, 3-Moderate, 2-Slight, 1-Poor. Wash and Rubbing fastness: 5-Excellent, 4-Very good, 3-Good, 2-Fair, 1-Poor.

present ready improved test was carried out using day light as a source of light. This requires use of standard dyed pattern with increasing light fastness properties. Such standard samples are available and the procedure according to specification laid down by the international organization for standardization (I.S.O.) (Trotman, 1970a). These standard samples have light fastness properties in a decreasing order and their fastness properties in a decreasing order from 8 to 1, the order indicating a decrease in the fastness properties.

3.4.2. Wash fastness

A soap solution which was recommended for I.S.O. Test (Trotman, 1970b) was prepared by dissolving soap (5 g) in distilled water (100 mL). The test dye pattern and undyed pattern were then treated with 20 mL of the soap solution for 45 min at 90 0C. After treatment, the test pattern and undyed pattern were removed from soap solution bath and washed for 5-10min in cold running tap water. The pattern was squeezed and dried at 50 0C. Loss in depth of shade of dyeing pattern and staining on another undyed pattern were assessed with gray scale. Gray scale (Trotman, 1970c) for alteration of color, consisting of grade 1 to 5.

3.4.3. Rubbing fastness

The specimens are placed in the Crockmeter, which causes a piece of standard white cloth (starch free 96 x 100 cotton fabric long type) to rub against the colored specimen under control condition of pressure and speed. The rubbing fingers are covered with white cloth, both for the dry test and wet test, and slight back and forth for 20 rubbing stocks. The color transferred to the white cloth is compared with Gray scale. Gray scale for alteration of color, consisting of grade 1-5.

The dyed polyester fabric showed fair to very good light fastness (4-6 values on gray scale) and very good to excellent washing and rubbing fastness (4-5 values on gray scale) properties. Dyes 4c, 4e, 4f and 4jhaving higher value of light fastness (6), this is due to the introduction of acetamido group ortho to the azo group, results in a significant improvement in the light fastness properties. The intramolecular hydrogen bonding between acetamido and azo group is responsible for the higher value of light fastness. The fastness properties data are summarized in Table 5.

4. Conclusion

In conclusion, we have developed an efficient and simple protocol for the synthesis of monoazo disperse dyes by conventional method in good yield and were confirmed by IR, *H NMR, 13C NMR and elemental analysis. All the dyes applied on polyester fabrics by HTHP method gave purple, violet and blue colored shades with fair to very good light fastness and very good to excellent washing and rubbing fastness properties.

Acknowledgements

The authors wish to thank the S.A.I.F, Punjab University, Chandigarh for analysis of spectral data and Atul Ltd., Valsad for providing dyeing & analytical facility, fastness test and some important chemicals.

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