Research Article - (2023) Volume 14, Issue 3
Received: 23-Oct-2022, Manuscript No. AASRFC-22-14578; Editor assigned: 25-Oct-2022, Pre QC No. AASRFC-22-14578 (PQ); Reviewed: 08-Nov-2022, QC No. AASRFC-22-14578; Revised: 02-Jan-2023, Manuscript No. AASRFC-22-14578 (R); Published: 09-Jan-2023
Organic dyes were synthesized and characterized by 1H NMR, 13C NMR, DEPT, and FTIR techniques. The characterization analysis of the organic dyes confirmed the preparation of, 2-naphthol-aniline, aniline black, and P-hydroxy azo-3-benzene carboxylic acid. Organic dyes are widely used in our daily life in clothing, paper, rubber, plastics, footwear, cosmetics, pharmaceutical, and food industries.
Organic dyes; FTIR analysis; 1H NMR analysis; 13C NMR analysis
A dye is a colored substance that is chemically bound and adheres to the substrate of understudy. In an aqueous solution, the coloring material is normally added, and a mordant may be needed to improve the fiber's dye speed. Both colors and pigments are light, so it absorbs only some wavelength. Dyes are colored since they absorb light (400 nm-700 nm) in the visible spectrum, have at least one chromosphere (color group) is required, they have a conjugate spectrum. Networks i.e. they contains double bonds alternating with single bonds in the compound. The concerned structures have electron resonance stabilizing power. When all of these features are absent from the composition of the molecules the color is lost. In addition to chromospheres, most colors contain auxochromes (color aids) such as carboxylic acid, sulfonic acid, amino acid, and hydroxyl groups. Although they are not responsible for color, they can change the color of a colorant and are most typically used to impact dye solubility. Coloring has been widely used in the clothing, paper, rubber, plastics, footwear, cosmetics, pharmaceutical, and food industries, generating huge quantities of colored wastewater every year and poisoning significant environmental problems for natural streams, rivers, and, consequently, for public health [1]. Much later, the first recorded use of organic dye was 4000 century years ago, when the blue dye indigo was discovered in mummy wraps in Egypt, tombs [2]. There are about 100,000 commercially available dyes, with over 7,107 tons of dyestuff produced annually around the world. Textiles, food cosmetics, and paper printing are among the industries that employ these dyes, with the textile industry being the major user of dyes [3]. Synthetic organic dyes, such as direct dyes, processing dyes, reactive dyes, and so on, are increasingly widely used in the textile industry. To produce more appealing, common shades of fabrics for a competitive market, a wide range of dyes and chemicals are used to make them very complex environmental problems related to the production and use of dyestuffs have developed dramatically over the past decade and are undoubtedly among the major driving forces affecting the textile dye industry today [4]. The term 'natural dye' encompasses all dyes derived from natural sources, such as plants, animals, and minerals. Many natural dyes are nonsubstantive and must be added to textiles using mordents, typically a metallic salt, with an affinity for both the coloring matter and the coloring matter fiber [5]. Synthetic dyes are commonly used in a large range of industries, including the main textile manufacturing industries consumers [6]. Methyl Orange (MO) is a common and typical azo anionic dye. This water soluble organic synthetic dye has a very high colorability and presents a bright orange color when dissolved in water. Azo dyes such as methyl orange contain aromatic and azo groups in their molecules, which are highly toxic, carcinogenic, teratogenic, and are harmful to the environment and organisms (Figure 1) [7,8].
Figure 1: Structural formula of methyl orange.
Methylene Blue (MB) was first synthesized for the textile industry in 1876. MB is the most common coloring cationic dye. Typically, it is used to dye cotton, wool, and silk. Scientists like Robert Koch and Paul Ehrlich realized MB potential for use in microscopic stains. Observing selective staining and microbial species inactivation led to aniline based dyes being tested against tropical diseases. MB was the first compound of this kind to be administered to humans and was shown to be effective in malaria treatment. MB was also the first synthetic compound ever used in clinical therapy as an antiseptic. Indeed, before the advent of sulfonamides and penicillin, the use of MB and its derivatives was widespread [9]. Moreover, MB is used for several therapeutic and diagnostic procedures in human and veterinary medicine, including as a stain in bacteriology, as a colorimetric redox agent, a melanoma targeting agent, a methemoglobinaemic, and antidote, an antiseptic, and disinfectant. Also, MB is used medically in a wide range of conditions including methemoglobinemia emergency treatment, ifosfamide induced encephalopathy and cyanide, nitrate, or carbon monoxide is poisoning, and intraoperative tissue staining [10]. One of the most common clinical applications of MB is for the treatment of drug induced methemoglobinaemia, industrial chemicals such as nitrophenols, or environmental poisons such as excessive nitrate in well water or cyanide compounds. Furthermore, MB is used to treat many psychiatric disorders due to the anxiolytic and therapeutic properties related to its ability to block guanylcyclase activation by nitric oxide. Nonetheless, in 2011, the United States food and drug administration published a safety warning about the possibility of serotonin syndrome when MB is administered in combination with serotonergic psychiatric drugs (Figure 2) [11, 12].
Figure 2: Structural formula of methylene blue.
Most of the chemicals and reagents used are of analytical grade purity and can be used indefinitely for purification. The chemicals and the reagents that were used in this study together with their specifications. Aniline, Hydrochloric acid (HCl), distilled water, Sodium Nitrite solution (NaNO2), 2-naphthol, Sodium Hydroxide (NaOH), glacial acetic acid, Potassium Dichromate (K2Cr2O7), Sulfuric Acid (H2SO4), Salicylic acid (C7H6O3), methylene blue and methyl orange dyes and Sodium Chloride (NaCl).
Synthesis of Dyes
Synthesis of 2-naphthol aniline dye: 4.5 ml of aniline was taken in a 500 ml beaker then 15 ml concentrated hydrochloric acid was added. 10 ml distilled water was gradually added and stirred. A saturated solution of NaNO2 (27.97 mmol, 4 g) with 10 ml water was created. In another beaker, (49.94 mmol 7.2 g) of 2-naphthol was taken and 60 ml of 10% sodium hydroxide solution was added to dissolve it. Beaker A-aniline+hydrochloric acid+distilled water. Beaker B-Sodium nitrite solution, beaker C-solution of 2-naphthol with sodium hydroxide, all beakers A.B.C were kept for cooling to 0 to 50°C an ice bath. After cooling tube B was slowly added to tube A while stirring to make benzene diazonium Chloride. After cooling tube C was added into tube A, stirring a precipitate was appear, It appears an orange-red color (2-naphthol aniline dye) that is heavy enough to form a precipitate, then filtered off and wash the crude sample with cold water, using glacial acetic acid, dry and recrystallize it. The weight of the compound that obtained from preparation was (49.54 mmol, 12.3 g), and therefore the residue had 94.61% yield. The compound had melting point 123°C. The synthesis reaction is shown in Figure 3.
Figure 3: Synthesis of 2-naphthol aniline.
Synthesis of Aniline Black
3.399 mmol, 1 g of potassium dichromate was measured and added to tube A containing 1 ml of concentrated sulfuric acid with 100 ml of distilled water. In tube B, 0.5 ml of aniline with 1 ml of concentrated hydrochloric acid. Tube B was added to tube A, stirring, and heating the mixture for 5 minutes. A black precipitate appeared, left the mixture to cool, and then the precipitate was filtered off. The weight of the compound that obtained from preparation was (2.377 mmol, 3.2 g). The residue had 59.37% yields. The synthesis reaction is shown in Figure 4.
Figure 4: Synthesis aniline black.
Synthesis of P-hydroxyl azo-3-benzene carboxylic acid
Diazotization: 3-benzene carboxylic acid 30 ml of aniline was measured and poured into 25 ml of HCl, the solution was hot. 1 M NaNO2 solution was produced by measuring (100 mmol, 6.90 g) of NaNO2 in 100 ml of water stirred and kept in an ice bath. To help cool to a lower temperature of 5°C, it was agitated rapidly and continuously. Coupling of carboxylic acid 3-benzene Salicylic acid, (50,03 mmol, 6.91 g) (0.05 mol), was diluted in 38 ml of 2.5 M NaOH. For 15 minutes, the mixture was stirred at 0°C-5°C. The mixture was then boiled in a hot water bath until all of the solids had dissolved. To further reduce the product's solubility, (136.9 mmol, 8 g) of NaCl was added. After purification, and filtering, a dark brown color appeared. The weight of the compound that obtained from preparation was (30.98 mmol 7.5 g). The residue had 9.4% yields. The compound had melting point 172°C. The Synthesis reaction is shown in Figure 5.
Figure 5: Synthesis of P-hydroxy azo-3-benzene carboxylic acid.
Preparation of Aqueous Methylene Blue and Methyl Orange Dyes Solutions
In this work, 10 ppm of methylene blue and methyl orange dyes were prepared. The preparation of the stock solutions was performed using a certain amount of solid dye and dissolved in a portion of water in the volumetric flask.
Characterization of Organic Dyes
FTIR spectroscopy: FTIR spectrum of the 2-naphthol aniline, aniline black, and P-hydroxy azo-3-benzene carboxylic acid extract was measured (as KBr discs) in the range of 400-4000 cm-1 on FT-IR spectrophotometer (Shimadzu FTIR-8400 S, Kyoto, Japan). The important IR bands, such as Ê? (C–N), Ê? (O–H), Ê? (CH), Ê? (C=C), Ê? (NH), Ê? (CO) and (CH) symmetric and asymmetric stretching, and stretching frequencies were studied to determine the presence of functional groups of organic dyes.
NMR Spectroscopy
1H NMR spectroscopy: The NMR spectrum of isolated products was obtained on a DRX-400 (1H 400 MHz) instrument from BRUKER (Karlsruhe, Germany). Tetra methyl silane was used as an internal standard. Proton chemical shifts are expressed in ppm (d) in comparison to internal Tetra methyl saline (TMS, d 0.0 ppm) or the solvent reference in comparison to TMS (CDCl3, d 7.26 ppm) and (DMSO, d 2.5 ppm). The following information is provided: Multiple (s), doublet (d), triplet (t), quartet (q), multiple (m), coupling constants (Hz), integration.
13C NMR spectroscopy: Carbon NMR spectra were acquired with complete proton decoupling on a varian 400 (100 MHz) or 500 (125 MHz) spectrometer. Chemical changes in carbon are reported in ppm (d) relative to TMS, with the solvent resonance as the internal standard (CDCl3, d 77.0 ppm) and (DMSO, d 40 ppm. All NMR spectra were acquired at ambient temperature.
FTIR Analysis of Synthesized Dyes
FTIR spectrum of 2-naphthol aniline dye compounds deployed a band at 3500 cm-1 due to the vibration frequency of the (OH) group. The (N=N) showed as a strong band at 1496 cm-1 and (C-N) at 1450 cm-1 stretch. In addition, the IR spectrum deployed two bands at 1617 cm-1 and 1548 cm-1 signals to the (C=C) groups respectively. The (CH) vibration frequency was displayed at 2940 cm-1 (Table 1 and Figure 6).
| Band | Absorption beam cm-1 |
|---|---|
| OH | 3500 cm-1 broad |
| N=N | 1496 cm-1 stretch |
| C=C | 1548 cm-1, 1617 cm-1 |
| C-N | 1450 cm-1 |
| C-HSP2 | 2940 cm-1 |
Table 1: FTIR absorption bands of 2-naphthol aniline.
Figure 6: FTIR spectrum of 2-naphthol aniline.
The FTIR spectrum is of aniline black was confirmed by presence of two peaks at 3410 cm-1 and 3203 cm-1 due to (-NH2) and (-N-H) bond stretching, respectively and (C-H aromatic) at 2998w, 2990 w cm-1, and signals to the (C=C) groups at 1560s, 1600s cm-1 ( Table 2 and Figure 7).
| Band | absorption beam cm-1 |
|---|---|
| NH2 | 3410 cm-1 |
| N-H | 3203 cm-1 |
| C-HSP2 | 2998w, 2990w cm-1 |
| C=N | 1560s cm-1 |
| Note: s: strong; w: weak. | |
Table 2: FTIR absorption bands of aniline black.
Figure 7: FTIR spectrum of aniline black.
The FTIR spectrum of P-hydroxyl azo-3-benzene carboxylic acid compound deployed a band at 3402 cm-1 stretching to the vibration frequency of (OH) group. In addition, the IR spectrum deployed two bands at 3336 cm-1 and 1573 cm-1 a signal to the (OH) bending and excess (C=O) groups respectively. The (N=N) showed a strong band at 1493s cm-1. The CH vibration frequency displayed at 3200 w cm-1, C-N vibration 1460 mcm-1 whereas the bending frequency of CH group due to the aromatic area displayed at 740s, 686s cm-1 triple compensation aromatic ring. It should be noted that the compound contains residues diazon salt (Table 3 and Figure 8).
| Band | absorption beam cm-1 |
|---|---|
| Ph-OH | 3402 cm-1 |
| N=N | 1493s cm-1 |
| OH | 3336b cm-1 |
| C=O | 1573 cm-1 |
| C-HSP2 | 3200w cm-1 |
Table 3: FTIR absorption bands of P-hydroxy azo-3-benzene carboxylic acid.
Figure 8: FTIR spectrum of P-hydroxy azo-3-benzene carboxylic acid.
NMR Analysis of Synthesized Dyes
NMR spectra of 2-naphthol aniline: Figure 9 shows the 1H NMR spectra of 2-naphthol aniline dye at room temperature in CDCl3 solvent. In 1H NMR spectrum, appearance of signal at δ 6.9 ppm supported the presence of (O-H) group. Which showed the presence of signals in aromatic region at 7.4 to 8.56 ppm respectively? Further integration value for protons supported the formation of the compound 2-naphthol aniline. Figure 10 is shows 13C NMR spectrum of 2-naphthol aniline, the presence of signals in aromatic region at δ 119.9 to 140.13 ppm respectively. Presence of a down field signal at δ 144.69 ppm, confirm the presence of the (OH) attached carbon in the target compound 2-naphthol aniline (calcd, 248.2 for C16H12N2O).
Figure 9: 1H-NMR-spectrum of 2-naphthol aniline (400 MHz, CDCl3).
Figure 10: 13C-NMR and DEPT (90 and 135)-spectrum of 2-naphthol aniline (400 MHz, CDCl3).
NMR Spectra of Aniline Black
Structure compound of aniline black was elucidated by 13C NMR and 1H NMR: (400 MHz, DMSO, 25°) in 1H NMR spectrum, appearance of signal at δ 3.60 ppm supported the presence of N-H primary group, and signal at δ 10.3 ppm supported the presence of N-H scenery group. And showed the presence of signals in aromatic region δ 6.77, 7.23, 7.12, 7.23, 6.77 ppm; 13C NMR: (400 MHz, DMSO, 25°C): δ121.0, 129.3, 127.6, 129.6, 123.1 ppm respectively.
Presence of a down field signal at δ 132.4 ppm, confirm the presence of the nitrogen attached carbon in the target compound (Calcd, 93 for C6H7N) (Figures 11 and 12).
Figure 11: 1H-NMR-spectrum of an aniline black (400 MHz, DMSO).
Figure 12: 13C-NMR and DEPT (90 and 135) spectrum of an aniline black (400 MHz, DMSO).
NMR Spectra of P-hydroxy azo-3-Benzene Carboxylic Acid
Figure 13 shows the 1H NMR spectra of (P-hydroxy azo-3-benzene carboxylic acid) at room temperature in DMSO solvent. The 1HNMR spectrum appearance of signal at δ 10.5 ppm supported the presence of (O-H) group, and showed proton an expansion of the signals between 6.8 and 7.9 ppm; groups resonating at δ 6.8,6.9,7.44,7.54,7.70,7.79, 7.88 and 7.9 ppm respectively. 13CNMR data Figure 14 showed intense signals attributed to signals at δ 172.35 ppm (attached to carbocyclic acid) δ 161.6 ppm (attached to hydroxyl), and δ 132.5, 136.3 (attached to azo group) δ 119.7, 130.1, 130.9, 130.2, 122.0, 117.5, 128.4, 123.6 and 113.4 respectively (Calcd, 242.23 for C13H10N2O3).
Figure 13: 1H-NMR-spectrum of P-hydroxy azo-3-benzene carboxylic acid) (400 MHz, DMSO).
Figure 14: 13C-NMR and DEPT (90 and 135) spectrum of P-hydroxy azo-3-benzene carboxylic acid (400 MHz, DMSO).
Organic dyes can be prepared successfully in the laboratory. The prepared dyes, their chemical composition, were identified by using FTIR and NMR spectroscopy. The results showed that the compounds were highly pure and were easy to identify, read and interpret.
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Citation: Khobrani SHA (2023) Synthesis and Characteristics of Some Organic Dyes. Adv Appl Sci Res. 14:109
Copyright: �???�??�?�© 2023 Khobrani SHA. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
