A periodical of the Faculty of Natural and Applied Sciences, UMYU, Katsina
ISSN: 2955 – 1145 (print); 2955 – 1153 (online)
ORIGINAL RESEARCH ARTICLE
*1Magaji Ibrahim Yohanna., 1Ameuru Umar Salami., 1Yakubu. Muhammed Kabir, 1Giwa Abdulraheem
1Department of Polymer and Textile Engineering, Ahmadu Bello University, Zaria, Nigeria
*Corresponding authors’ email: ibrahimmagaji63@nilest.edu.ng
Various bifunctional reactive dyes were synthesized based on a naphthalimide derivative with a tetrazotised cyanurated coupling component, such as H-acid, R-acid, J-acid, ℽ-acid, and Tobias acid. The synthesized dyes were purified by recrystallization. The structures of the synthesized dyes were confirmed using UV–vis, FT-IR, MS, and 1H NMR spectroscopic techniques. Spectrophotometric investigations of the dyes in solvents of different polarities were performed to obtain absorption maxima, molar extinction coefficients, and salvochromic effects. These dyes give a percentage yield of 76-88%, a molecular weight of 1262.85-1454.98 g/mol, and a melting point of 300-306 ℃. The dyes produced brown, purple, orange, pink, and yellow colours on cotton fabrics and chrome-tanned leather. The differences in dye colour could be attributed to both the chromophore and the position of the substituent in different coupling components. The dyes showed satisfactory performance, with percentage exhaustion ranging from 70-89% and fixation ranging from 64-93% on the substrate. The fastness properties to washing rating very good to excellent (4-5), to light fastness rating good to very good (5-6), and to perspiration to both the alkaline and acidic rating, very good to excellent (4-5) media of the dyes on chrome tanned leather and cotton fabrics showed good to excellent performance. The study was confined to cotton under laboratory conditions, and further work is needed to test its behavior on other cellulosic materials and to assess its environmental performance. Overall, the findings substantiate the potential for naphthalimide-derived from bifunctional reactive dyestuffs as a versatile class of fiber-selective colorants for cellulose textile applications.
Keywords: Synthesis, Nitration, Oxidation, Amination, Purification, Fastness properties
Synthetic organic colorants underpin the aesthetic and functional performance of thousands of products across many industrial sectors, such as textiles, paper, plastics, leather goods, coatings, cosmetics, and food. Ever since the introduction of the first synthetic dyes in the mid-nineteenth century, synthetic dyes have largely replaced natural colorants due to their superior performance, color palette, improved fastness properties, and economies of scale enabled by chemical synthesis. It is also possible to customize the molecular structure, resulting in dyes with targeted affinities for other substrates and performance profiles (Benkhaya et al., 2020; Al-Tohamy et al., 2022).
This synthetic flexibility permits the production of a vast structural variety, which may be tailored to yield almost any color, including the entire visible spectrum. Moreover, numerous azo dyes have high molar extinction coefficients, equivalent to high tinctorial power, and moderate to good fastness to light, washing, and perspiration, indicating that azo reactive dyes can be used in a wide variety of demanding applications (El-Sayed et al., 2024).
Reactive dyes are extensively used in the textile industry not only to colour cotton, but also wool and silk, because of their wide range of colour shades, high wet-fastness properties, and ease of application. New developments in azo dye synthesis have opened up the prospects of naphthalimide derivatives in the textile industry. As reviewed by Dodangeh et al. (2021), Gharanjig et al. (2017) originally synthesized monoazo disperse dyes based on N-ester-1,8-naphthalimide for dyeing polyester-cotton blends, which showed good thermal stability and dyeing fastness. This highlights the relevance of naphthalimide-based azo dyes for improving textile performance.
Ameuru et al. (2018) also demonstrated the industrial value of naphthalimide derivatives and their use in dyeing polyester fabrics at high temperatures without the addition of a dispersing agent, while preserving good fastness characteristics. Al-Majidi and Al-Khuzaie (2019) also prepared new azo compounds bearing a 1,8-naphthalimide group by condensing 1,8-naphthalic anhydride with p-phenylenediamine or benzidine. These were also diazotized and condensed with substituted phenols to yield azo products that can serve as acid-base indicators, demonstrating the chemical versatility of these structures. Reported literature on naphthalimide-based monoazo dyes has so far been confined largely to polyester substrates, where the dyes have performed well in terms of visible absorption but merely satisfactory fastness properties. The structural differences and the dyeing conditions resulted in wash and perspiration fastness between grades 4 and 5, and light fastness between grades 3 and 6 (Pendo et al., 2023).
In comparison, there are not many studies on nylon and other polyamides. The limited experiments conducted on naphthalimide-based acid dyes on these substrates exhibit exhaustion values of about 65-70% under acidic exhaustion dyeing conditions, with wash and perspiration resistance typically Grade 4, and light fastness typically Grade 3-4 (Shaki et al., 2015; Hosseinnezhad et al., 2017). Moreover, colorimetric shade differences in nylon 6.6 have not been systematically and comprehensively reported, leaving a gap in knowledge of the behavior of these types of acid dyes on polyamide fibers. This deficiency underscores the need for targeted research on the shade tunability and fiber-dye interactions, as well as the fastness performance of such systems under standard test conditions (Epolito et al., 2005).
Reactive dyes are coloured compounds which contain one or two groups capable of forming a covalent bond between a carbon atom or phosphorous atom of the dye ion or molecule and an oxygen atom, nitrogen or sulphur atom of a hydroxyl, an amino or a mercapto group respectively, of the substrate (Zollinger, 1991) have reported fibre-reactive dyes for silk, wool, and cotton. Mono azo reactive dyes and bis azo reactive dyes have been established as a major group for fixation to cellulose. Bisazo reactive dyes have been widely considered due to their higher fixation yields on various fibres. The purpose of the present investigation is to obtain reactive dyes with a higher degree of reactivity. We report here the synthesis and study of the dyeing properties of bifunctional reactive dyes based on naphthalimide derivatives. Several researchers have reported on the synthesis, characterization of bifunctional reactive dyes on cotton fabric, but there is no existing literature with regard to the synthesis of bifunctional reactive dyes derived from naphthalimide derivatives, which is a new heterocyclic intermediate. The presence of the naphthalimide moieties in the dye structure will improve the fastness properties of the dyes in cotton fabric and bring about deep shade, brilliant hues of high bathochromic effects due to donor donor-acceptor character of the amino and carbonyl groups present in the naphthalimide moiety. This investigation aimed to synthesize, characterize, and apply bifunctional reactive dyes based on naphthalimide derivatives.
The following are some of the major equipment that were used in the course of the research includes; UV-Vis measurement was performed using a PerkinElmer Lambda 25 spectrophotometer in a 1 cm quartz cuvette with distilled water as the reference, and measurements were taken between 200-800 nm range, FT-IR Spectrophotometer (Agilent Technology Mode Cary 630), Nuclear Magnetic Resonance (NMR) (Agilent Technology Mode 400 MHZ) GC-MS analyses were also carried out using an Agilent Technologies 7590B GC coupled to a 5977A MSD instrument operated in electron ionization (EI, 70 eV) mode;, Most commercial products used in the synthesis of bifuctional reactives dye were purchased from sigma-Aldrich and Weifang Senya chemical company limited, China. All the chemicals and reagents used in the present study, such as: Acenaphthene (purity ≥ 98%), Sodium dichromate (purity ≥ 98%), Hydrazine hydrate (purity ≥ 98%), Stannous chloride (purity ≥ 99%), 8–amino–1–naphthol–3,6–disulfonic acid (H2SO4). 2-naphthol-3-6 disulforic acid (purity ≥ 99%) (R-acid), 2-amino-1-naphthalene sulfuric acid (purity ≥ 99%), 4-amino butanoic acid, 2-amino-1-naphthalene sulfuric acid (purity ≥ 99%), Tridichloro-1,3,5-triazine (purity ≥ 99%).
Acenaphthene (15.4 g, 0.1 mol) was dissolved in hot acetic acid (57.2 cm³), cooled with vigorous stirring to separate the crystalline acenaphthene as finely as possible. Nitric acid (7.03 cm3) was added dropwise for 1 hour at 22-27 °C, then stirred for 1 hour more at 25 °C, and gradually warmed to 68 °C for 30 min then cooled, and the crystals were filtered, washed with acetic acid - water (1: 1) followed by distilled water to give needle like crystals (Ameuru et al., 2018).
Scheme 1: Synthesis of intermediate A Ameuru U. S(2018)
Scheme 1: Synthesis of intermediate A Ameuru U. S(2018)
5-Nitroacenaphthene (24.87 g, 0.125 mol) was dissolved in hot acetic acid (248.75 cm³). Sodium dichromate (Na2Cr2O7· 2H2O) (158.5 g) was added for 3 hours at 65-70 °C. This was gradually warmed to 98-100 °C for 30 min and then refluxed for 5 hours. The content was washed with 0.6 L of hot water, cooled, filtered, and the solid was washed with dilute HCl. It was further boiled for 30 min. with 200 cm3 of 5% Na2CO3 solution for 30 min., filtered, and the filtrate was acidified, and the separated crystals were dried at 120 °C for 4 hours to obtain 4-nitro-1, 8-naphthalic anhydride, which was recrystallized from HNO3 to afford the off-white needle-like crystals (Ameuru et al., 2020)
A suspension of 4-nitro-1’8-naphthalic anhydride (0.02 mol, 4.86 g) and hydrazine hydrate (0.03 mol, 4.71g) was stirred under reflux for 7 hrs in ethanol (102 cm3). The cooled suspension was filtered and recrystallized from ethanol, yielding a light brown product.
Scheme 1 Synthesis of 6, 6’-diamino-1H, 1’H, 3H, 3’H-[bibenzo[de]isoquinoline]-1, 1’3, 3’-tetraone,
The intermediate (0.54 g, 0.005 mol) is suspended in distilled water (60 cm³), and hydrochloric acid (0.36 g) is added dropwise to the well-stirred suspension. The mixture is gradually heated to 70 0C until a clear solution is obtained. The form solution is gradually cool to below 5 0C in an ice bath, then already cooled (0-5 °C) NaNO2 (0.6g in 4 cm3 of H2O) is added over a period of 30 mins with continuous stirring. The stirring is continued for one (1) hour, maintaining the temperature of 0-5 °C with a positive test for nitrous with starch iodide paper. After completing the destruction of the excess of nitrous acid with the required amount of sulphamic acid, the clear tetrazonium solution at 0-5 0C obtained is use for the next coupling as shown in scheme A. (Ameuru et al., 2020)
Scheme 2 Synthesis of 1,1.3.3’-tetraoxo-1.1’.3.3’-tetrahydro-[2,2’-bibenzo[de]isoquinoline]-6,6-bis(diazonium)chloride
Cyanuric chloride (1.85g 0.01 mol) is stir in acetone (25cm3) at a temperature below 5 0C for a period of an hour. A neutral solution of the coupling component (3. 19g, 0.01 mol) in aqueous sodium carbonate solution (10% W/v) is then added in small lots for an hour. The pH is maintained neutral by simultaneous addition of sodium carbonate solution (1% W/v). The reaction mass is then stirred at 0-5 °C for a further 4 hours. The cyanurated coupling component solution is use for subsequent coupling reaction in various acids such as H, Gamma, R, J, and Tobias acid respectively (Oforghor, 2021)
Scheme 3 Procedure for cyanuration of coupling components.
Scheme 4 Synthesis of 3, 3'-((1E, 1'E)-(1, 1', 3, 3'-tetraoxo-1, 1', 3, 3'-tetrahydro-[2, 2'-bibenzo[de]isoquinoline]-6, 6'-diyl)bis(diazene-2, 1-diyl))bis(7-((4, 6-dichloro-1, 3, 5-triazin-2-yl)amino)-4-hydroxynaphthalene-2-sulfonic acid)
The synthesis of dye A1-D5 was done by adding a freshly prepared solution of tetrazotized ion 6, 6’-diamino-1H, 1’H, 3H, 3’H-[bibenzo[de]isoquinoline]-1, 1’3, 3’-tetraone. The pH 7.5-8.5 was maintained by simultaneous addition of sodium carbonate solutions (Na2SO) (10% w/v), yielding a purple solution. The stirring was continued for 4 hrs at a constant temperature of 0-5°C, followed by 1hr. The solid dye precipitates out and is filtered, with a little amount of acetone, and dried at room temperature (Oforghor, 2021)
The synthesized dyes were purified by recrystallization from ethanol by adopting the method used by Alaa and Tarek (2006).
Determination of Percentage Yield of the Synthesized Dyes
The percentage yield of the synthesized dyes was determined using equation 1.1 (Gregory, 2005)
%Yield = \(\frac{MP}{MMP}\) ÷ \(\frac{MR}{MMR}\) × 100 ………………………………………………. . 1.1
where;
MP is the mass of the product
MMP is the molar mass of the product
MR is the mass of the reactant
MMR is the molar mass of the reactant
Melting points of the synthesized compounds were determined on a Gallenkamp melting point apparatus (model CD10127). A small amount of each dye was placed in a capillary tube and inserted into the apparatus. The melting point of each dye was obtained by consistently focusing on the apparatus as it gradually heated the dye in the tube.
The molar extinction coefficient (Ԑ), which is a constant for each molecule at any given wavelength, represents the absorbance per liter. This was calculated using the relationship,
Log10 (Io/I) absorbance A or optical density
ƐCL. . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . 1.2
Ԑ = Molar Extinction Coefficient
A = Absorbance at λmax
C = Concentration of dye in Mol/dm3
L = Path length in cm
FTIR spectra were measured on a Shimadzu FTIR-84005 spectrometer, in a wavelength range of 4000-400 cm -1 using KBr pellets; a polystyrene film standard was used to calibrate the instrument.
About 1.5 mg of finely ground synthesized sample was intimately mixed with about 150 mg of powdered potassium bromide (KBr) in a mortar with a pestle. The finely ground mixtures were introduced between the two bolts (A and A1), and the upper screw A was tightened until the powder was compressed into a thin disc. After compression, the sample bolts A and A1 were removed, and a steel cylinder with a pellet inside was placed in the path of the IR spectrometer beam, and a blank KBr pellet was placed in the path of the reference beam. The sample was run.
UV-Vis measurements were performed using a PerkinElmer Lambda 25 spectrophotometer in a 1 cm quartz cuvette with distilled water as the reference, and measurements were taken over the 200-800 nm range. The wavelength of maximum absorption of each dye was determined in distilled water, ethanol, Ethanol ± HCl, and dimethylformamide (DMF). 0.001g of each dye was dissolved in 5 cm3 of each of the solvents. The spectra of each dye solution were determined and recorded using UV-Visible scanning.
Dyeing Of Cotton with synthesized dyes was carried out using 2 g of fabric, liquor to goods ratio 1:10 0.100 g L1 Na 2SO 4 (Sodium sulphate), and 10 g L1 Na2 CO3 (Sodium Carbonate) under the fixation of 60 ℃ isothermal process was used. After dyeing, the shopping was carried out using 2 g L-1 non-ionic surfactant at 90–95 ℃ for 20–30 min, and the sample was lastly cleaned and dehydrated.
Cotton fabric was dyed by the exhaust method using an Ahiba Datacolor IR dyeing machine (Model 2000). Dyebaths were prepared at a concentration of 3% on weight of fabric (owf) using an acetic acid–sodium acetate buffer adjusted to pH 4.5. One gram of cotton fabric was introduced into a dyebath (liquor ratio 50:1) at 40 °C, raised at 1.5 °C/min to 100 °C, and held for 60 minutes with agitation. After dyeing, all the samples were hot rinsed and treated with 1 g/l of soaping agent, followed by cold rinsing and air-drying (Clark, 2011; Tanning of hides and skins 1989).
Dye uptake was determined by measuring the absorbance of diluted dye bath samples at the maximum absorbance wavelength. The bath was sampled before and after dyeing. A 1 mL aliquot was taken from the bath and diluted to 20 mL with distilled water. This is to ensure that the absorbance falls within the readable range of 1.5. The percentage dye bath exhaustion (%E) for each substrate was calculated using equation 3.4 (Kamel, et al.,2014; Sekar and Deulgaonkar, 2007).
% E = Ao ─ A1 × 100----------------------------------------------------3. 4
Ao
Where Ao and A1 are the absorbance at λmax of the dye bath prior to dyeing and after dyeing, respectively.
The term fixation ratio refers to the ratio of the amount of dye absorbed (which is covalently bonded to the fibre) to the hydrolyzed dye on the surface of the surface.
Percentage fixation = \(\frac{{OD}_{1} - {OD}_{2} - {OD}_{3}}{{OD}_{1 - {OD}_{2}}} \times\) 100----------------------------------------3.5
Where OD 1 = optical density of the dye before dyeing
OD2 = optical density of the dye after dyeing
OD3 = optical density after stripping
Each dyed fabric was stripped in a 25% (w/w) pyridine in water solution (100 °C, IR 10:1) for 30 minutes, and a portion of the solution was taken to the spectrophotometer to give OD3, the optical density after stripping.
Optical overall fixation efficiency value (T) is related to the original amount of dye applied. A simple relationship exists between % T % F, and % E (dye bath exhaustion) given by:
Using ISO Number 3 test methods, the washing conditions were adopted as shown below for the determination of wash fastness of a dyed sample.
Soap 5 g/l
Soda ash 2 g/l
Liquor ratio 50:1
Temperature 60 + 2 °C (140 + 4°F)
Time 30 min.
The dyed fabric (10 cm x 4 cm) was sandwiched between undyed nylon and undyed cotton fabrics and stitched. The composite sample was washed together using the above specification, and the change in colour and staining of the adjacent fabric were assessed using a grey scale (Choi et al., 2008)
Light fastness was determined by exposing the dyed nylon and eight wool blue standards on a Xenotest 150 (Original Hanau, chamber temperature 25-30°C, black panel temperature 60°C, relative humidity 50- 60%, and dark glass (UV) filter system) for 48 hours (Alaa and Tarek, 2006).
The perspiration fastness was carried out in both acidic and alkaline solutions using the standard ISO-E04
Sodium chloride (5 g/l), disodium hydrogen orthophosphate (Na2HPO4..2H2O) (2.5 g/l), Histidine mono-hydrochloride monohydrate, (C6H9O2N3. HCl. H2O) (0. 5 g/l). The solution was brought to pH 8 using 0.1N NaOH solution.
Sodium chloride (5 g/l), sodium dihydrogen orthophosphate (NaH2PO4. 2H2O) (2. 2 g/l), Histidine mono-hydrochloride-monohydrate, (C6H9O2N3HCl. H2O) (0.5 g/l). The solution was brought to pH 5.5 using 0.1N acetic acid solution.
The composite specimen was thoroughly wetted out in the alkaline solution (pH 8.5) at a liquor ratio of 50:1 and kept standing for 30 minutes at room temperature. The specimen was placed between two plates of the perspirometer at a pressure of 12.5 kPa, which was achieved by placing a 4.5 kg weight on the arranged samples in the perspirometer. The perspirometer was set up in the oven at 37 0C and maintained for 4 hours. The procedure was repeated for the other composite specimens at pH 5.5 for acid, and they were placed in another perspirometer. The samples were removed, opened up, and allowed to dry at room temperature. Both specimens were then assessed for colour change of the test fabric and staining of the adjacent fabric (Koh et al., 2003)
Table 1.1: Structures of Synthesized intermediate, molecular formula their IUPAC Name
| INTERMEDIATE No. | NAME | STRUCTURE | MOLECULAR FORMULA |
|---|---|---|---|
| A | 6, 6'-diamino-1H, 1'H, 3H, 3'H-[2, 2'-bibenzo[de]isoquinoline]-1, 1', 3, 3'-tetraone |  |
C24H14N4O4 |
Table 1.2: Structures of Synthesized reactive dyes, molecular formula, and their IUPAC Name
| DYE No. | STRUCTURE | MOLECULAR FORMULA | |
|---|---|---|---|
| A1 | 3, 3'-((1E, 1'E)-(1, 1', 3, 3'-tetraoxo-1, 1', 3, 3'-tetrahydro-[2, 2'-bibenzo[de]isoquinoline]-6, 6'-diyl)bis(diazene-2, 1-diyl))bis(7-((4, 6-dichloro-1, 3, 5-triazin-2-yl)amino)-4-hydroxynaphthalene-2-sulfonic acid) |  |
C50H24Cl4N14O12S2 |
| A2 | 3, 3'-((1E, 1'E)-(1, 1', 3, 3'-tetraoxo-1, 1', 3, 3'-tetrahydro-[2, 2'-bibenzo[de]isoquinoline]-6, 6'-diyl)bis(diazene-2, 1-diyl))bis(6-((4, 6-dichloro-1, 3, 5-triazin-2-yl)amino)-4-hydroxynaphthalene-2-sulfonic acid) |  |
C50H24Cl4N14O12S2 |
| A3 | 8, 8'-((1Z, 1'Z)-(1, 1', 3, 3'-tetraoxo-1, 1', 3, 3'-tetrahydro-[2, 2'-bibenzo[de]isoquinoline]-6, 6'-diyl)bis(diazene-2, 1-diyl))bis(1-((4, 6-dichloro-1, 3, 5-triazin-2-yl)amino)naphthalene-2-sulfonic acid) |  |
C50H24Cl4N14O10S2 |
| A4 | 4, 4'-((1Z, 1'Z)-(1, 1', 3, 3'-tetraoxo-1, 1', 3, 3'-tetrahydro-[2, 2'-bibenzo[de]isoquinoline]-6, 6'-diyl)bis(diazene-2, 1-diyl))bis(5-((4, 6-dichloro-1, 3, 5-triazin-2-yl)amino)-3-hydroxynaphthalene-2, 7-disulfonic acid) |  |
C50H24Cl4N14O18S4 |
| A5 | 3, 3'-((1E, 1'E)-(1, 1', 3, 3'-tetraoxo-1, 1', 3, 3'-tetrahydro-[2, 2'-bibenzo[de]isoquinoline]-6, 6'-diyl)bis(diazene-2, 1-diyl))bis(5-((4, 6-dichloro-1, 3, 5-triazin-2-yl)amino)-4-hydroxynaphthalene-2, 7-disulfonic acid) |  |
C50H24Cl4N14O18S4 |
Table 1.3: Physical properties of the synthesized dye intermediates.
| Name of Intermediate | Colour of Crystals | Melting point (°C) | Percentage yield (%) | Molecular weight (g/mol) | Molecular formula |
|---|---|---|---|---|---|
| A | Dark brown | 278-280 | 96 | 422. 0 | C24H14N4O4 |
Table 1.4: Physical properties of the synthesized bifunctional reactive dyes derive from naphthalimide derivatives.
| Dyes No | Molecular formulae | Theoretical molecular weight (g/mol) | Melting point (℃) | Percentage yield (%) | Colour of the crystals |
|---|---|---|---|---|---|
| A1 | C65H28CL4N14O1854 | 1454. 98 | 304-306 | 82 | Blue |
| A2 | C65H28CL4N14O18S4 | 1454. 98 | 300-302 | 74 | Red |
| A3 | C56H28CL4N14O1852 | 1294. 85 | 300-302 | 88 | Brown |
| A4 | C56H28CL4N14O1252 | 1294. 85 | 308-310 | 80 | Black |
| A5 | C56H28CL4N14O1052 | 1262. 85 | 300 302 | 76 | Orange |
Table 1.5: Wavelength of Maximum Absorption and Molar Extinction Coefficient of the Dyes
| Dye No | Ԑmax in DMF × 104 (L/mol-1 cm-1) | Distil H2O λmax (nm) | DMF λmax (nm) | Ethanol λmax (nm) (a) | Ethanol + HCl λmax (nm) (b) | Change in λmax (nm) (b-a) |
|---|---|---|---|---|---|---|
| A1 | 2. 77 | 511 | 525 | 509 | 514 | +5 |
| A2 | 2. 80 | 498 | 521 | 519 | 515 | -4 |
| A3 | 3. 28 | 494 | 511 | 510 | 494 | -16 |
| A4 | 2. 26 | 515 | 422 | 509 | 494 | -15 |
| A5 | 8. 21 | 449 | 511 | 510 | 511 | +1 |
Table 1.6: Infrared Spectra of the Synthesized Intermediates Based on Naphthalimide Derivatives
| A-3067(N. H Str Vibr), 2784(C-H Str Vibr), 2583 (C-H Str Vibr Aliphatic), 2106 (C\(\equiv C\) Str Vibr Ar), 1622 (C=O Str Vibr), 1670 (-N-C=O Str Vibr), |
Table 1.7: FT-IR Analysis of the Synthesized Bifunctional Reactive Dyes
| Dye No | FT-IR (cm-1) |
|---|---|
| A1 | 3204 (OH Str Vibr) 3070 (C-H Str Vibr) 2121 (C-H Str Vibr) 1778-1707 (C=0 Str Vibr)1599-1299 (C-N Str Vibr) 1648 (N-H bend Vibr) 1372 (N=0 Str Vibr) 709-743 (C-Cl Str Vibr) 877-862 (SO3H Str Vibr) |
| A2 | 3432 (OH Str Vibr) 2840-2985 (C-H Str Vibr) 1797 (N=N Str Vibr) 1648 (N-H bend Vibr) 1439-1417 (C-N Str Vibr) 1041 (S=0 Str Vibr) 862 (SO3H Str Vibr) 709-766 (C-CL Str Vibr) 1372 (N-O Str Vibr) |
| A3 | 3592 (OH Str Vibr) 3439 (NH Str Vibr) 2840-2996 (C-H Str Vibr) 2508-2162 (-SCN Str Vibr) 1748 (C=0 Str Vibr) 1648 (N-H bend Vibr) 1588 (N=N Str Vibr) 1369 (N=0 Str Vibr) 1417-1439 (C-N Str Vibr) 728-762 (C-CL Str Vibr) 829 (SO3H Str Vibr) 992 (SO3H Str Vibr) |
| A4 | 3435 (OH Str Vibr) 2870-2985 (C-H Str Vibr) 1819 (C-O Str Vibr) 1704-1745 (-N-C Str Vibr) 1588-1652 (-N=N Str Vibr) 724-762 (C-CL Str Vibr) 829-940 (SO3H Str Vibr) |
| A5 | 3432 (OH Str Vibr) 3238 (NH Str Vibr) 2840 -2985 (C-H Str Vibr) 1704-1748 (C-O Str Vibr) 724-762 (C-CL Str Vibr) 829-992 (SO3H Str Vibr) 1588-1648 (-N=-N Str Vibr) |
Table 1.8: Gas chromatography mass spectroscopy of synthesized intermediate based on naphthalimide derivatives
| Intermediate code | Empirical formula | Experimental value of m/z fragment | Corresponding positive charge fragment | theoretical value |
|---|---|---|---|---|
| A | C 24 H14 N4 O4 | 43. 0, 75. 0, 105. 0 177. 0, 207. 0 422. 0 |
C2 H5 NO2+ C6 H5 N2 +, C12 H5 NO+ C12 H7 N4 + C17 H3 N3 O4+ M+ | 422.40 |
Figure A: TT-IR Spectra of Intermediate A
Figure A: 1. FT-IR Spectra of dye A1
Figure A. 2. FT-IR Spectra of dye: A2
Figure A. 3. FT-IR Spectra of dye A3
Figure A. 4. FT-IR Spectra of dye A4
Figure A. 5. FT-IR Spectra of dye A5
Figure A6: GC-MS Spectra of Intermediate A
Figure B. 1HNMR spectra of Intermediate A
Figure B. 1HNMR spectra of Dye A1
Figure B. 1HNMR spectra of dye A2
Figure B. 1HNMR spectra of dye A3
Table 1.9: Exhaustion and fixation of the synthesized bifunctional reactive dyes on cotton fabric and chrome-tanned leather
| Dye | % Exhaustion On Cotton /CTL | % Fixation On Cotton | Shade On Fabric |
|---|---|---|---|
| A1 | 78. 50, 63.10 | 89. 10 | Pink |
| A2 | 84. 00, 68.50 | 90. 00 | Purple |
| A3 | 87. 20, 75.30 | 90. 53 | Pink |
| A4 | 74. 90 | 68. 30 | Ash |
| A5 | 81. 30 | 72. 41 | Yellow |
CTL=Chrome Tanned Leather
Tables 1.10: The fastness properties of the synthesized bifunctional reactive dyes on cotton fabric
| Dye No. | Light Fastness | Wash Fastness (CC) | Perspiration Fastness – Acid (CC) | Perspiration Fastness – Alkaline (CC) |
|---|---|---|---|---|
| A1 | 5 | 4 | 5 | 5 |
| A2 | 5–6 | 4 | 4 | 5 |
| A3 | 5 | 4 | 5 | 4 |
| A4 | 4 | 4 | 5 | 4 |
| A5 | 4 | 5 | 3–4 | 5 |
CC= Colour Change
Table 1.11: Light, wash and perspiration fastness properties of chrome tanned dyed leather.
| Dye No. | Light Fastness | Wash Fastness (CC, CTL) | Perspiration Fastness – Acid (CC, CTL) | Perspiration Fastness – Alkaline (CC, CTL) |
|---|---|---|---|---|
| A1 | 5 | 4–5 | 3–4 | 4–5 |
| A2 | 5–6 | 4 | 4–5 | 5 |
| A3 | 5 | 4 | 4 | 4 |
CC= Colour Change CTL=Chrome Tanned Leather
Displayed the structures of synthesized intermediates using acenaphthene as a starting material, and several reaction steps like nitration, oxidation, amination, and reduction were involved to obtain the intermediates, with the colour crystals dark brown, melting point ranging 278-2800C percentage yield ranging from 58-98% and the molecular weight range from 422. 40 (g/mol).
The dichlorotriazine dyes A1-A5 have moderate to higher molecular weights ranging from 1186. 76 -2097. 87 (g/mol), which translates to a higher melting point range from 300-338 (℃). The percentage yield of the synthesized dyes is also very high, although very few have low yields, ranging from 68-92 %. The high percentage yield recorded indicates that the experimental conditions were controlled (Alaa and Tarek, 2006). The synthesized dyes were also very soluble in water which is an indication that the structure of the synthesized dyes are highly branched and the position of the functional groups in the carbon chains also favours the solubility of the dyes (OH, SO3 H) (Patel and Patel, 2014; Patel Pratixa et al.,2015);. The colour or hue of the synthesized bifunctional dyes ranges from blue, brown, orange, black, purple, red, and pink due to the presence of functional groups such as NH2 and -OH on the dye structure.
Spectroscopic characteristics of the synthesised bifunctional reactive dyes A1-A5 based on naphthalimide derivatives
The visible absorption maxima of the synthesised bifunctional reactive dyes as recorded in Table 1.7 felt within the visible region (400 - 700 nm) of the electromagnetic spectrum. The values of the molar extinction coefficient (ε) that were determined by Beer-Lambert's law are in the range of 2.26×10—4 –8. 21×10-4 ( L/mol-1cm-1), which is an indication of high absorption intensity of the synthesised bifunctional reactive dyes in DMF, respectively. However, the synthesised bifunctional reactive dyes have different chromophoric functionalities but the same bridging groups, and it is also apparent that the value of λmax depends on the coupling components used. The presence of electron-donating or electron-attracting (withdrawing) groups at suitable positions on the coupler ring affects the absorption characteristics of the synthesised azo-reactive dyes (Patel and Patel, 2014). The wavelength of maximum absorption (入max) appeared in the visible region of the spectrum, which is attributed to the p-p⃰. Reaction of 6, 6-diamino 1H, 1’H, 3h, 3’ H (2, 2’ – bibenzo [de] isoquinoline ] 1, 1’3, 3 – teraone with cyanurated H-acid gave dye A1, which absorbed at 525 nm in DMF, 511nm in distilled water,509 nm in ethanol and 514 nm in ethanol plus HCL which dye A1 in DMF is more bathachromic which could be attributed to the presence of electron donating or electron attracting (withdrawing) groups at the suitable position of the coupler ring and polar excited states of the synthesised bifunctional reactive dyes are stabilized by polarization interactions forces as the polarisability of the solvent increases but when cyanurated H-acid was replaced with cyanurated R-ac id which gave dye A2 and absorbed at 521 nm, which gave hypsochronic shift of 4 mm when compared to dye A1. This agrees with the findings of Koh and Greaves (2013) and the presence of an electron acceptor group in the teteazo components and an electron-donating group in the coupler. Replacing cyanurated R with J-acid dye A3 was synthesized, which absorbed at 511 nm in DMF and gave a hypsochromic shift of 14 nm positive solvatochromic when compared to dye A1 and a hypsochromic shift of 10 nm negative solvatochromic when compared to dye A2 due to the presence of the sulphonic group and tetra azo component on the coupling components. Meanwhile, replacing J-acid with gamma–acid, dye A4 was synthesized, which absorbed at 422 in DMF and gave a hypsochromic shift of 103 nm compared to dye A1, a hypsochromic shift of 99 nm compared to A2, and a hypochromic shift of 87 nm compared to dye A3, respectively. However, replacing cyanurated gamma-acid with Tobias acid, dye A5 was synthesized absorbed at 511 nm in DMF and gave a hypsochromic shift of 14 nm when compared to A1, hyposchromic shift of 10 nm when compared to dye A2 when compared to dye A3 at on the same wavelength, when compared to dye A4 bathochromic shift 89 nm respectively.
6, 6- diamino 1H, 1H, 3H, 3H – (2, 2- bibenzo [de] isoquinoline) -1, 1’ 3, 3’ – tetraone, being a naphthalimide derivative, is synthesized by the reaction of acenaphthene as a starting material, and several reaction steps like nitration, oxidation, amination, and reduction were involved. The crystal colour, yield, and melting point were dark brown, 58 %, and 278-280 ℃, respectively.
The IR spectrum of the synthesised intermediate A showed all the basic functional groups indicated by the characteristic bands (stretching and bending vibration). The infrared (KBr cm-1 Figure 1. A) spectrum of the synthesized intermediate A spectrum shows a signal at 3067 for NH/OH stretching vibration, at 2784 C-H stretching vibration, at 2583 C-H aliphatic stretching vibration, at 2106 C=C alkyne stretching vibration, at 1670-N-C=O stretching vibration, and at 1622C=O stretching vibration. The H’ NMR spectrum (Figure B. 1) shows peaks 6. 27-4. 42 ppm, which corresponds to the proton on the amine group. The peaks at 7. 78-7. 94ppm (13H, 7Ht) correspond to the (13H, 7H) at the aromatic region of the spectrum. The peak at 7. 22-7. 41ppm corresponds to the (8H, 12H d) at the aromatic region of the spectrum. The mass spectrometry MS (Figure A6) analysis showed positive charge fragments like C2 H5 No+, C6 H5 N+, C12 H5 No+, C12 H7 N+4, C17 H3 N3 O+4, M+ with a corresponding mass to charge ratio (M/Z) of 43. 0, 75. 0, 105. 0, 177. 0, 207. 0, 422. 0. The molecular ion (M+) peak at M/Z is 422.0 which is in agreement with the formula mass 422.40g/mol.
Dye A1 was synthesized by tetrazotizing 6, 6-diamino 1H, 1H, 3H, 3’H (2, 2-bibenzo[de] isoquinoline) 1, 1’3, 3-tetraone with cyanurated H-acid. The crystal colour, percentage yield, and melting point were Blue, 82%, and 304-306℃, respectively. The IR spectrum of the synthesized dye A1 showed all the basic functional groups indicated by the characteristic bands (stretching and bending vibration) at the IR spectra IR vmax cm-1), Figure A, 1,) of the dye A1 showed stretching vibration at 3204 for OH, 3070 for C-H, N-H stretching vibration at 2121. For C-H, 1599 for N=N 1648 for N-H bend vibration 1299 for C-N stretching vibration, at 1372 for N=O, C-C, l709-743 cm-1 stretching vibration.
The H’NMR spectrum (Figure B, 2) (400 MHz, DMSO) shows a peak at 2. 0-3. 43 ⸹ ppm corresponds to the proton on the sulphonic group (S03H), the peak at 4. 0-5. 25 ⸹ ppm corresponds to the proton on the amine group (NH), the peak at 5. 35-5. 51 ⸹ ppm corresponds to the proton on the hydroxyl group (OH). The peak at 7. 22-6. 94 ⸹ ppm corresponds to the aromatic region of the spectrum. The peak at 7. 78-7. 74 ⸹ ppm corresponds to the aromatic region of the spectrum.
Dye A2 was synthesized by tetrazotizing 6, 6-diamino 1H, 1H, 3H, 3’H (2, 2-bibenzo (de) isoquinoline) 1, 1’3, 3-tetraone with cyanurated R-acid. The crystal colour, percentage yield, and melting point were red, 74%, and 300-302 ℃, respectively. The IR spectrum of the synthesized dye A2 showed all the basic functional groups, as indicated by characteristic bands (stretching and bending vibrations). The IR spectrum (IR vmax cm) Figure A2) of the dye A2 showed stretching vibration at 3432 O-H, -2840-2985 C-H stretching vibration 1791 N=N stretching vibration, 1648 N-H bending vibration 1439-1417 C-N stretching vibration, 1372 N-O stretching vibration. 709-766 cm-1 C-Cl stretching vibration. The H’NMR spectrum (Figure B, 2) (400 MHz, DMSO) shows a peak at 2. 0-3. 43 ⸹ ppm corresponds to the proton on the amine groups ( NH ), the peak at 10.05-10. 25 ⸹ ppm corresponds to the proton on the hydroxyl group protons (OH), the peak at 11. 35-12. 25 ⸹ ppm corresponds to the proton on the sulphuric group (SO3H ). The peak at 7. 16- 8. 15 ⸹ ppm corresponds to the aromatic group protons of the spectrum.
Dye A was synthesized by tetrazotizing 6, 6-diamino 1H, 1H, 3H, 3’H (2, 2-bibenzo (de) isoquinoline) 1, 1’3, 3-tetraone with cyanurated J-acid. The crystal colour, percentage yield, and melting point were Brown, 88%, and 300-302 ℃, respectively. The IR spectrum of the synthesized dye A3 showed all the basic functional groups indicated by the characteristic of the band. (Stretching and bending vibration. The (IR Vmax cm-1) (Figure A. 3) of the dye A3 showed stretching vibration at O-H 3592, N-H stretching vibration at 3439 C-H stretching vibration at 2840-2996, -S-C-N stretching vibration 2508-2162, C-O stretching vibration at 1748, N-H bending vibration at 1648, N-O stretching vibration 1369, C-N stretching vibration 1417-1439, N=N stretching vibration at 1588, C-Cl stretching vibration at 728-762 cm-1. The H’NMR spectrum (Figure B, 2B) (400 MHz, DMSO) shows a peak at 12.00-12. 30 ⸹ ppm corresponds to the proton on the sulphonic group (S03H), the peak at 9.95-10.35. ⸹ ppm corresponds to the proton on the amine group (NH), the peak at 5. 35-5. 51 ⸹ ppm corresponds to the proton on the hydroxyl group (OH) . The peak at 7. 78-9. 95 ⸹ ppm corresponds to the aromatic protons region of the spectrum.
Dye A4 was synthesized by tetrazotizing 6, 6-diamino 1H, 1H, 3H, 3’H (2, 2-bibenzo [de] isoquinoline) 1, 1’3, 3-tetraone with cyanurated ℽ-acid. The crystal colour, percentage yield, and melting point were Black, 80%, and 308-3010 ℃, respectively. The IR spectrum of synthesized dye A4 showed all the basic functional groups, as indicated by characteristic bands (stretching and bending vibrations). The IR spectrum (IR Vmax cm-1) Figure A-4 of the dye A4 showed stretching vibration at O-H 3435, C-H stretching vibration at 2840-2985, C-O stretching vibration at 1819 N-C stretching vibration at 1704-1745, N=N stretching vibration at 1588-1652, C-Cl stretching vibration at 724-762 SO3H stretching vibration 829-940 cm-1.
Dye A5 was synthesized by tetrazotizing 6, 6-diamino 1H, 1H, 3H, 3’H (2, 2-bibenzo [de] isoquinoline) 1, 1’3, 3-tetraone with cyanurated Tobias-acid. The crystal colour, percentage yield, and melting point were Orange, 76%, and 300-302 ℃, respectively. The IR spectrum of synthesized dye A5 showed all the basic functional groups, as indicated by characteristic bands (stretching and bending vibrations). The IR spectrum (IR Vmax cm-1) Figure A-5 of the dye A5 showed stretching vibration at OH 3432, N-H stretching vibration 3238, C-H stretching vibration at 2840-2985, C-O stretching vibration at 1704-1748, C-Cl stretching vibration at 724-762, SO3H stretching vibration at 829-992 N=N stretching vibration at 1588-1648 cm-1.
The light-fastness rating of the dyed fabric is shown in Table 1.8. The test is carried out by exposing each dyed sample to daylight alongside eight blue wool standards. It was observe that light fastness of dye A1, A2, and A3 which is obtained by coupling tetrazonium salt with 2- naphthol 3-6 difulfonic acid, 8-amino-1-naphthol -3-6 disulfonic acid, 2-amino-8-naphthol sulfonic acid and 2-amino-5-naphthol-7-sulfonic acid to obtained bifunctional reactive dyes gave a light fastness rating (3-5) moderate, good and very good on chrome tanned leather (Clark, 2011). The type of bridging group used in the dye synthesis plays an important part. High ratings of strength properties are given by the covalent bonding connections between the dye and fibre (J.E. Ishegbe et al., 2014) Other dyes gave very good to excellent fastness this, may attributed to the molecular structure of the dyes, planarity and dye substituents that provided shield from radiant energy on azo chromophores, therefore, the this effect conferred good light fastness properties on the dyes (Sekar and Deulgaonkar, 2007).
It is a very important requirement that coloured fibres withstand the conditions they may encounter during processing, the following colouration, and their subsequent daily use. Wash fastness testing is important when bifunctional reactive dyes are used, as the dyes are soluble in water. In water if not covalently bonded to the fabric, the dyes may be lost during washing. This makes wash fastness testing an important parameter for assessing this requirement, and it involves determining the resistance of dyes to alkaline washing (Table 1.11). It shows the wash fastness of the dyes coupled with terazonium salt, cyanurated 2-naphthol, 3,6-disulfonic acid, and 8–amino–1–naphthol; 3,6. Disulphonic acid, 2-amino-8-naphthol sulphonic acid. These dyes gave purple, brown, and pink hues with brighter and deeper shades, high tinctorial strength, and excellent levelness on the substrates, ranging from good (3), very good (4), to excellent (5). (Dye – A1-A3) gave a wash fastness rating on chrome-tanned leather (3-5) good, very good, and excellent, while on cotton fabric gave a wash fastness rating (5) excellent. It was found that the substituents with higher electron-donating property afforded lower hydrolysis rate constants. It could be seen that cotton fabric showed better wash fastness than chrome tanned leather, which could be due to the fabric's texture: cotton involves high diffusion and penetration, whereas chrome tanned leather, being an interweave, involves slow diffusion and penetration (Ezeribe, et al., 2013). Bifunctional reactive dyes exhibited good to excellent fastness to washing on cotton fabric while the dyes showed good to excellent fastness to washing on chrome tanned leather respectively and this may be due to the presence of solubilising group and covalent linkage which affect solubility and washing ability of the dye-out of the dyed chrome tanned leather While the wash fastness of the dyes coupled with terazonium salt, each portion of dye A1 –A5 solution gave a wash fastness rating on chrome tanned leather (3-5) good, very good and excellent, while on cotton gave a wash fastness rating (4-5) very good and excellent The high ratings of fastness properties could be referred to the covalent binding linkages between the dye and fiber (Ukanah et al., 2020) The wash fastness property of the chrome tanned leather and cotton dye fabrics were generally good very good to excellent.
In conclusion, we reported the synthesis of bifunctional reactive dyes with naphthalimide derivatives were synthesized starting with the following reaction: nitration, oxidation, amination, and reduction to synthesize the intermediate A [6, 6’-diamino-1H, 1’H, 3H, 3’H-[bibenzo[de]isoquinoline]-1, 1’3, 3’-tetraone,] which was tetrazotised with cyanurated coupling components such as H-acid, R-acid, J-acid, ℽ -acid, and Tobias acid. The synthesized dyes were purified by the recrystallization method. The structure of the synthesized dyes were comfirm using UV –visible,, FT-IR, MS and 1HNMR spectroscopic technique., Spectrophotometric investigations of the dyes in solvents of different polarities were measured to obtained absorption maxima, molar extinction coefficient and salvatochromic effects These dyes gives percentage yield of 76-88%, molecular weight of 1262.85-1454.98 g/mol, melting point 300-306 ℃ with various hues such as blue, red, brown, black and orange crystals respectively. The planarity of molecules and solvent polarity play important roles in the emission spectra of dyes. The chemical link between cellulose and a covalent bond, which is particularly resistant to acid hydrolysis, gives synthetic colours and their exceptional durability. The MCT groups' presence enhances the dye's substantivity and demonstrates strong wash-off and high fastness. The dyes produced brown, purple, orange, pink, and yellow colours on cotton fabrics and chrome-tanned leather. The difference in colour of the dyes could be attributed to both the nature and position of the substituent and the various coupling components. The dyes gave satisfactory performance, with percentage exhaustion ranging from 70-89% and fixation ranging from 64-93% on cotton fabrics. The fastness properties to washing rating very good to excellent (4-5), to light fastness rating good to very good (5-6), and to perspiration to both the alkaline and acidic rating, very good to excellent (4-5) media of the dyes on chrome tanned leather and cotton fabrics showed good to excellent performance. The presence of the triazine group in the dye molecule improves exhaustion, fixation, and fastness properties. Furthermore, the use of large quantities of salt and alkali is widely considered ecologically unfavorable; therefore, the development of novel modifications to the dye structure and the use of minimum salt for application are of great interest. Furthermore, the use of large quantities of salt and alkali is widely considered ecologically unfavorable; therefore, the development of novel modifications to the dye structure and the use of minimum salt for application are desirable.
We are grateful to the faculty of Engineering at Ahmadu Bello University for supporting this research. Ibrahim Yohanna Magaji also expresses gratitude to the staff of the Department of Polymer and Textile Engineering for their kind scrutiny and collaboration.
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