Synthesis and characterization of reactive dyes based on 2-phenyl-3-[4′-(4″-aminophenylsulphonamido)]phenyl-4(3H)-quinazolinone-6-sulphonic acid

2.1 General

All the melting points (m.p.) were determine in open capillaries and are uncorrected and expressed in °C. The purity of all the dyes has been checked by TLC (Fried and Sharma, 1982). The IR spectra were recorded in KBr on a Perkin Elmer Model-881 spectrophotometer and ¹H NMR spectra were recorded on a Brucker DRX-300 (300 MHz FTNMR) instrument using TMS as internal standard and DMSO as solvent, where the chemical shift δ are given in ppm. Absorption spectra were recorded on a Beckman DB-GT Grating spectrophotometer. The light fastness was assessed in accordance with BS: 1006–1978 (Test Method, 1006). The rubbing fastness test was carried out with a Crockmeter (Atlas) in accordance with AATCC (1961) and the wash fastness test in accordance with ISO: 765–1979 (Indian standard, 1979).

2.2 Preparation of 2-phenyl-4-oxo-3,1-benzoxazine-6-suphonic acid (A) Trivedi et al., 2004

Benzoyl chloride (140.5 g, 1 mol) was added drop wise to a solution of 5-sulfo anthranilic acid (217 g, 1 mol) in pyridine (60 ml), with constant stirring at 8 °C over the period of one hour. After the completion of addition, the reaction mixture was stirred for half an hour at room temperature. At the end of the reaction solid mass was obtained, it was filtered, washed successively with sodium bicarbonate solution (to remove unreacted acid). Finally washed with water, dried and recrystallize from rectified spirit (Scheme 1).

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Scheme 1

The route of the synthesis of the 2-phenyl-4-oxo-3,1-benzoxazine-6-sulphonic acid (A).

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Yield 85%, m.p. 107 °C, IR (KBr): ν_max (cm⁻¹) 1750 (C⚌O), 1380 (C–N), 1042 (S⚌O). Elemental analysis: Found C-55.38%; H-2.94%; N-4.55%; C₁₄H₉O₅NS (Calculated C-55.44%; H-2.99%; N-4.62%).

2.3 Preparation of 4′,4″-diaminodiphenylsulphonamide(DADPSA) (B)

The title compound was prepared according to the literature procedure (Zhang et al., 1999) (Scheme 2).

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Scheme 2

The route of the synthesis of the 4′,4″-diaminodiphenylsulphonamide (DADPSA) (B).

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2.4 Preparation of 2-phenyl-3-[4′-(4”-aminophenylsulphonamido)]-phenyl-4(3H)-quinazolinone-6-sulphonic acid (C) Pandey et al., 2007

A mixture of 2-phenyl-4-oxo-3,1-benzoxazine-6-sulphonic acid (A) (0.05 mol) and 4,4′ diaminodiphenyl sulfonamide (B) (0.05 mol) in dry pyridine (50 ml) was refluxed for 6 h under anhydrous reaction conditions. The resulting mixture was then cooled to room temperature. The reaction mixture was treated with 10% dil. HCl and stirred. A solid separate out which was filtered off and washed with water to remove any adhered pyridine. The crude quinazoline thus obtained was dried under vacuum and recrystallize from 95% ethanol (Scheme 3).

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Scheme 3

The route of the synthesis of the 2-phenyl-3-[4′-(4″-aminophenylsulphonamido)] phenyl-4(3H)-quinazolinone-6-sulphonic acid (C) and its diazonium salt (D).

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Yield 75%, m.p. 130 °C. IR (KBr): ν_max (cm⁻¹) 3510 (NH₂ Primary), 2925, 2850 (C–H), 1665 (C⚌O), 1390 (C–N), 1045 (S⚌O for –SO₃H), 1350, 1164 (S⚌O for –SO₂NH). ¹H NMR (DMSO-d₆) (chemical shift δ in ppm) 5.75 (2H, s, –NH₂), 8.85 (1H, s, –SO₂NH), 11.4 (1H, s, –SO₃H), 6.70–8.10 (16H, m, Ar-H).

Elemental analysis: Found C-56.86%; H-3.62%; N-10.15%; C₂₆H₂₀O₆N₄S₂ (Calculated C-56.92%; H-3.67%; N-10.21%).

2.5 Diazotisation of 2-phenyl-3-[4′-(4″-aminophenylsulphonamido)]phenyl-4(3H)-quinazolinone-6-sulphonic acid (D)

Hydrochloric acid (20 ml, 0.015 mol) was added drop wise to the stirred suspension of (C) (2.58 g, 0.005 mol) in water (60 ml) this well stirred suspension. The mixture was gradually heated up to 70 °C, till clear solution obtained then the solution was cooled to 0–5 °C in an ice bath. A solution of NaNO₂ (0.6 g) in water (4 ml) previously cooled to 0 °C, was then added over a period of 5 min with stirring. The stirring was continuous for an hour, maintaining the same temperature, with positive test for nitrous acid on starch iodide paper. After just destroying excess of nitrous acid with required amount of a solution of sulphamic acid. The clear diazo solution (D) at 0–5 °C was used for subsequent coupling reaction (Scheme 3).

2.6 Preparation of cyanuration of H-acid (G)

Cyanuric chloride (E) (1.85 g, 0.01 mol) was stirred in acetone (25 ml) at a temperature below 5 °C for a period of an hour. To the above stirred solution, a neutral solution of H acid (F) (3.19 g, 0.01 mol) in aqueous sodium carbonate solution (10% w/v) was then added in small portions for one hour. The pH was maintained neutral by simultaneous addition of sodium carbonate solution (1% w/v). The reaction mass was stirred continuously at 0–5 °C for four hours until clear solution was obtained (Scheme 4). The resultant solution was used for the next step without further purification.

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Scheme 4

The route of the synthesis of the cyanurated H-acid (G) and 4-chloro anilino cyanurated H-acid (H).

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2.7 Preparation of 4-chloro anilino cyanurated H-acid (H)

The solution of cyanurated H acid (G) (4.67 g, 0.01 mol) was stirred at 30–35 °C for half an hour. To this well stirred solution, 4-chloro aniline (1.28 g, 0.01 mol) was added drop wise during a period of half an hour, maintaining the pH neutral by simultaneous addition of sodium bicarbonate (15 w/v). After addition, the stirring was continued for further 3 h. The resultant solution (H) thus obtained was used for further coupling reaction (Scheme 4).

2.8 Formation of the dye D₁

To an ice cold and stirred solution of 4-chloro anilino cyanurated H-acid (H) (5.58 g, 0.01 mol), a freshly prepared diazo solution (D) (2.98 g, 0.005 mol) was added drop wise over a period of 10–15 min. The pH was maintained at 7.5–8.5 by simultaneous addition of sodium carbonate solution (10% w/v). During coupling the purple solution was formed. The stirring was continued for 3–4 h, maintaining the temperature below 5 °C. The reaction mixture was heated up to 60 °C and sodium chloride added until the colouring material was precipitated. It was stirred for an hour, filtered and washed with a small amount of sodium chloride solution (5% w/v). The solid was dried at 80–90 °C and extracted with DMF. The dye was precipitated by diluting the DMF-extract with excess of chloroform. A purple dye was then filtered, washed with chloroform and dried at 60 °C. Yield 85% (Scheme 5).

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Scheme 5

The route of the synthesis of the dye (D₁).

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According to the above procedure; other reactive dyes D_2–10 were synthesized using 4-chloro anilino cyanurated coupling components such as Gamma acid, J-acid, N-methyl J-acid, N-phenyl J-acid, Chicago acid, Laurant acid, Bronner acid, Tobias acid and K-acid. All the synthesized dyes were recorded in Table 1.

3.1 Spectral data

The visible absorption spectroscopic properties of dyes were recorded in water and are shown in Table 5. From the data reported in Table 5, it is apparent that the value of λ_max depends on the nature and position of coupling component used. The colour change observed for each dye is due to the oscillation of electrons and the presence of additional substituents. In D₁ there is more place for the oscillation of electrons and also the presence of both –OH and –NH– groups, thus λ_max = 540 nm (purple hue). In other dyes like D₂, D₃, D₄ and D₅ oscillation of electron is very fast due to the lesser number of electrons and hence these dyes possess lower λ_max value compared with D₁. The same effect is also revealed for the dyes D₇, D₈ and D₉. While for dyes D₆ and D₁₀ the substituent are same as in D₁ but the oscillation of electron is fast due to the locality of –NH₂ and –SO₃Na group. Thus; in both dyes neutralization of electron takes place rapidly, hence both dyes have lower λ_max compared with D₁.

The extent of this shift is probably accounted for the steric effects of the coupler substituents.

3.2 IR spectra

In general, the IR Spectra (Colthup et al., 1991; Bassler et al., 1991) of all the dyes, showed the characteristic band in the range 3500–3675 cm⁻¹ indicates the presence of O–H and N–H stretching vibration, in addition to absorption band at 1506–1520 cm⁻¹ is due to the N–H bending vibration. The band appeared at 1415–1440 cm⁻¹ is due to the stretching vibration of azo group. A strong band at 1650–1670 cm⁻¹ is due to the stretching vibration of the C⚌O group of the quinazoline moiety, and absorption band at 1380–1395 cm⁻¹ is due to the C–N stretching vibration. The band at 1040–1345 cm⁻¹ is due to the stretching vibration of S⚌O group, while the band at 1310–1325 cm⁻¹ is due to the bending vibration of O–H group and the C–Cl stretching vibration is appeared at 760–770 cm⁻¹ (Table 2).

3.3 ¹H NMR spectra

¹H NMR spectral data (Dean, 1968) (300 MHz, DMSO) of representative dye (D₁) Showed signal at 3.35 δ (1H, s, –OH), 4.14 δ (2H, s, –2NH), 8.82 δ (1H, s, –SO₂NH), 6.72 δ – 8.23 δ (23H, m, Ar-H) (Table 3).

3.4 Dyeing of fibres

All the D_1–10 were applied on silk, wool and cotton fabrics in 2% shade according to the literature procedure (Shenai, 1973) in the dye-bath containing the materials listed in Table 4. These dyes are gave reddish brown to orange hues with brighter and deeper shades with high tinctorial strength and excellent levelness on the fabric. The variation in the hues of the dyed fabric results from the alternation in the coupling components. The remarkable degree of levelness and brightness after washing indicates good penetration and excellent affinity of these dyes to the fabric.

3.5 Exhaustion and fixation study

The percentage exhaustion of 2% dyeing on silk ranges from 67–76%, wool range from 63–72% and cotton ranges from 65–74%. The percentage fixation of 2% dyeing on silk range from 84–92%, wool range from 84–93% and cotton ranges from 84–91%. The data percentage exhaustion on the various fabrics was calculated by known method (Erik, 1977) (Table 5).The higher exhaustion may be expected due to relatively open structure.

Dye uptake by the fiber was measured by sampling the dye bath before and after dyeing. The absorbance of the diluted dye solution was measured at λ_max of the dye. Percentage dye bath exhaustion was calculated using the following relationship. $$\%\text{Exhaustion}=\frac{\text{Initial}\text{O}.\text{D}.-\text{Final}\text{O}.\text{D}.}{\text{Initial}\text{O}.\text{D}.}\times 100$$

3.6 Fastness properties

The light fastness of all the dyes rating 3–6 for silk, wool and cotton which shows light fastness is moderate to very good. The wash fastness of all the dyes rating 3–5 for silk, wool and cotton which shows wash fastness is good to excellent. The rubbing (dry and wet) fastness of all the dyes rating 3–5 for silk, wool and cotton which shows rubbing fastness is good to excellent (Table 6).