Diazo Component Research Articles

Synthesis, recovery, and application of environmentally friendly disperse dyes with high light fastness

Dye wastewater has attracted great attention due to high pollution and toxicity which can cause harm to the living environment. It is common for azo-disperse dyes to be used to dye hydrophobic fibers. A reduction clearing method is used to eliminate the dye particles on the fabric after dyeing. However, when azo disperse dyes on the fiber surface are eliminated by the reduction clearing process, this can give rise to an effluent discharge due to the presence of sodium hydrosulfite. The introduction of carboxylic ester groups into dye molecules can effectively avoid this issue. Six novel environmentally friendly alkali-clearable disperse dyes, containing cyano and carboxylic ester groups, were readily synthesized by a diazo coupling reaction with various diazo components. Their dyeing properties on polyethylene terephthalate fabrics were respectively measured and compared with those of commercial reference dyes. It was indicated that some fastness properties of the synthesized dyes on polyethylene terephthalate fabrics after the alkali clearing were improved compared with those of the reference dyes due to the existence of the carboxylic ester group. Moreover, the chromaticity of dye wastewater can be further reduced by recovering hydrolyzed dyes.

Chemo- and Diastereoselective Entries into All-Carbon α-Quaternary Aldehydes via C-C Insertion of 4-Diazoisoquinolin-3-ones into C-CHO Bonds.

Herein, we describe a chemo- and diastereoselective formal C-C insertion reaction of 1,2-disubstituted 4-diazo-3(2H)-isoquinolones and 4-diazoisochroman-3-one into C-CHO bonds of aldehydes, delivering all-carbon α-quaternary aldehydes bearing medicinally important 1,4-dihydro-3(2H)-isoquinolone scaffold. Our protocol is enabled by the preferential 1,2-carbon migration over more common 1,2-H shift. The corresponding reaction tolerates a wide range of functionalities in both aldehyde and diazo components, giving the target homologated aldehydes in generally high yields. The synthetic utility of this method has been further showcased by some transformations of the formyl moiety.

Sc(OTf)3-promoted formal insertion of 4-diazo-1,4-dihydroisoquinolin-3-ones into C–H bond of 1,3-dicarbonyl compounds: Synthesis of 2-(3-oxo-1,2,3,4-tetrahydroisoquinolin-4-yl)-1,3-diarylpropane-1,3-diones

A facile and efficient synthesis of novel 2-(1,2,3,4-tetrahydroisoquinolin-4-yl)-1,3-diarylpropane-1,3-diones via the Sc(OTf)3-promoted reaction between 4-diazo-1,4-dihydroisoquinolin-3-ones and 1,3-dicarbonyl compounds is reported. This formal C–H bond insertion involves an activation of 1,3-dicarbonyl compounds with generation of triflic acid by-product, a formation of diazonium intermediate from diazo component by triflic acid promotion, and a subsequent intermolecular nucleophilic substitution step. Readily available starting materials, cheap catalyst, broad substrate scope (22 examples, up to 92% yield), and mild reaction conditions are the merits of this reaction.

Reaction of 2-methyl-2,3,5,6,7,8-hexahydro-4H-1,3-benzoxazin-4-one with diazonium salts

We found that the interaction of 2-methyl-2,3,5,6,7,8-hexahydro-4H-1,3-benzoxazin-4-one with various activated and non-activated diazonium salts in hydrochloric and acetic acids leads to the formation of corresponding previously unknown arylhydrazones with high yields, independent of the structure of the diazo component. The azo coupling reaction proceeds at the non-activated sp3-hybrid C-8 atom due to the activating action of the acid medium with the formation of 2-methyl-6,7-dihydro-2H-1,3-benzoxazine-4,8(3H,5H)-dione 8-arylhydrazone. This reaction proceeds regioselectively at the C-8 atom due to steric hindrances, namely the large size of the diazonium salts. The structures of the synthesized arylhydrazones were confirmed by modern physicochemical methods of analysis including 1Н NMR spectroscopy and mass spectrometry. The discovered reaction allows synthesizing arylhydrazones, which are difficult to access by other methods in one step. Isolation of the reaction products is not difficult and can be achieved by simple filtration after neutralization. The resulting arylhydrazones can be used as building blocks in organic synthesis and as ligands for binding metal ions.

Determination of water content in dimethyl sulfoxide/N,N-dimethyl formamide and methanol content in ethanol by solvatochromism of azo dye, 2-(tert-butyl)-4-methoxy-6-(naphthalen-1-yldiazenyl) phenol

A novel 2-(tert-butyl)-4-methoxy-6-(naphthalen-1-yldiazenyl)phenol (NAP) was synthesized by coupling reaction of 2-tert-butyl-4-methoxyphenol with diazotized naphthylamine as diazo component. The azo dye was characterized by NMR, FT-IR and UV–vis spectroscopic techniques. The visible spectrum of NAP was recorded in different solvents and at different pHs. NAP exhibited a large wavelength shift with increasing solvent polarity, showing significant color change over a wide range in different solvents. The determination of water content in organic solvents miscible with water such as dimethyl sulfoxide (DMSO)/N,N-dimethyl formamide (DMF) and methanol content in ethanol, which is also a common mixture were investigated with NAP which is azo dye. The present reported solvatochromic compound for the determination of water content in DMSO/DMF and methanol content in ethanol showed a fairly wide linear range compared to some previously reported solvatochromic compounds in the literature. In addition, the solvatochromism of NAP allows the determination of methanol content in ethanol, which has caused many deaths, with a fast, cheap and easy method.

Olefination of 3-Diazoindolin-2-imines with Hydrazones: An Approach toward Stereoselective Synthesis of (E)-3-Arylideneindolin-2-imines.

Stereoselective synthesis of (E)-3-arylideneindolin-2-imines from 3-diazoindolin-2-imines and hydrazones was achieved using copper bromide as the catalyst. The olefination reaction proceeded via copper-catalyzed aerobic oxidation of hydrazones to diazo compounds and copper-catalyzed cross coupling of two different diazo components in a tandem manner.

Synthesis and Properties of Novel Reactive Dyes Comprising Acyl Fluoride Group on Cotton Fabrics.

Novel reactive dyes with mono- and bi-acyl fluoride reactive groups have been designed and synthesized, which are obtained by using 2-amino-8-naphthol-6-sulfonic acid or 1-amino-8-naphthol-3,6-disulfonicacid as the coupling component and 4-aminobenzoyl fluoride (PABF) as the diazo component. Their structures have been defined by nuclear magnetic resonance spectroscopy and ultraviolet–visible spectra (UV—Vis). The novel reactive dyes were evaluated on cotton by using the exhaust dyeing method. The properties were examined in detail, and the results showed that the dye concentration of 4% (o.w.f), pH = 9, and salt-free was the most effective condition. The fixation of the novel reactive dyes on cotton was 60.27% and 64.13%, respectively. The micro-fluorine-containing reactive dyes have favorable dyeing properties owing to the covalent bond formed between the reactive group of dyes and the functional group of cotton fibers, which can achieve salt-free dyeing of cotton.

Urea-containing azo disperse dyes: Synthesis, application, and structure–property relationship for nylon fabrics

A group of new disperse dyes containing urea groups was synthesized by coupling various diazonium salt with urea-containing coupling components, which were prepared by the reaction between N-(2-Aminoethyl)-N-ethyl-3-methylbenzenamine and p-toluene isocyanate. Then, the structures of the synthesized dyes were characterized by 1H NMR, 13C NMR, FTIR, and MS analysis. The spectral characteristics of the dimethylformamide (DMF) solution and applied properties on the nylon fabric for all of the new dyes were assessed and compared with the amino-containing control dye. Correlations between molecular structure and dyeing properties on nylon fabric for the urea-containing dyes were investigated by using density functional theory (DFT). The results indicated that the dyeing rates of the dyes became slower, and the fastness properties on the nylon fibers, including washing, sublimation, and light, were greatly improved after the introduction of the p-toluenpiride group. The color performance, build-up, and light fastness properties of the urea-containing dyes varied with the diazo components, among which 4-nitroaniline and its cyano substituted analogues performed well. Both dye exhaustion and saturation adsorption on the nylon fabric were negatively correlated with the product (F2.F6) of the dipole moment of the dye (F2) and its molecular weight (F6). In addition, the ClogP value had a significant negative correlation with the washing change fastness, and the dipole moment of the dye was positively correlated with the sublimation change fastness. Also, the dyes with larger molecular volume and molecular weight had lower rates of sublimation changes and wet crocking fastness due to surface adsorption on the nylon fibers.

Relationship between Structure and Dyeing Properties of Disperse Dyes in D5 Medium

In this paper, two disperse dyes with different substituents were selected to dye polyester fabrics in decmethylcyclopentasiloxane (D5) medium. The structures and dyeing performance of the two dyes were studied and compared. The results showed that dyes with lower solubility in D5 medium had higher dyeing rates. DFT calculations showed that large steric hindrance of cyano groups on diazo components contributed to improving the dyeing rate. This was due to the generation of more monomolecular dyes by destroying π-π stacking interactions. These results provide theoretical guidance for improving the exhaustion and further promote the industrial development of disperse dye in a D5 dyeing system.

Investigation from molecular packing to application of azobenzene disperse dyes on polyester fabrics to realize waterless dyeing

In this paper, three azobenzene disperse dyes with different substituents were selected to investigate the structure-performance relationship derived from molecular structure. Their visible absorption performances were evaluated in DMF and further analyzed using density functional theory (DFT) method. The dyeing properties of these disperse dyes on polyester fabrics in low pressure waterless dyeing system were discussed by comparing solubility, K/S value, levelling and color fastness. Additionally, the X-ray crystal diffraction analysis was used to investigate the relationship between dyeing properties, the nature of chemical structure and substituents therein. Carefully analysis showed that the dyeing uptake increased by 31.1% due to an introduction of cyano group in the diazo component. Meanwhile, the substituent acetoxethyl in coupling component further increased the dyeing uptake to 97.4%, which was attributed to low solubility. Crystal structures confirmed compact molecular arrangement results in low solubility and actually beneficial for the high dyeing uptake due to strong intermolecular interactions. Incorporating an understanding of the molecular packing analysis into the development of disperse dyes can improve the performance and promote the sustainable development of textile industry.

Alkali-stable solid state fluorescent pyrazolo/pyrrolinone disperse dyes: Synthesis and application for dyeing polyester fabric

Six novel fluorescent disperse dyes were synthesized by diazo-coupling reaction. As dye intermediates, two diazo components having 5-amino-4-arylazo-3-methyl-1H-pyrazoles moieties were initially prepared, diazotized and coupled with three pyrrolinone esters (PES) derivatives to give azo-hydrazone pyrazolo/pyrrolinone derivatives. The dye structures were confirmed by FTIR, 1HNMR, mass spectroscopy and elemental analysis. The absorption spectra of the prepared dyes and its solvatochromic behavior were investigated. These dyes displayed significant emission spectra in polycrystalline (powder) form, but no fluorescence observed in solution. The dyes were applied on polyester fabric using conventional high temperature exhaustion dyeing method, exhibited high tinctorial strength and bright fluorescent orange to reddish violet colors on polyester fabric with dyeing stability under acidic, neutral and alkaline pH. The relationship among different dyeing pH and color difference effects for dyed fabrics were studied. It was found that disperse dyes containing phenylazo-pyrazolone structure showed better dyeing performance and alkali-stable dyeing properties on polyester fabrics than those containing nitrophenol derivatives. The color fastness to washing, perspiration, sublimation and light fastness were also investigated.

Synthesis of benzothiazole-azo disperse dyes for high resistance to alkaline treatments and peroxide bleaching

PurposeThis paper aims to synthesize benzothiazole-azo disperse dyes which can be applied not only for dyeing and alkaline reduction of polyester fabric in one bath, but also for dyeing and peroxide bleaching of cotton/polyester blend fabric in one bath.Design/methodology/approachThe synthesized benzothiazole-azo disperse dyes were confirmed by proton nuclear magnetic resonance (1H-NMR) spectroscopy, mass spectroscopy (MS) and UV–visible spectrophotometry. The performance on resistance to alkaline treatment and peroxide bleaching was tested by measuring the color strength of polyester fabric dyed with the synthesized benzothiazole-azo disperse dyes under high-temperature and high-pressure conditions.FindingsIncreasing the electron-withdrawing ability of the substituents in the diazo component and the electron-donating ability of the substituents in the coupling component resulted in a significant bathochromic shift of the maximum absorption wavelength. Except that the disperse dyes synthesized from the coupling components containing the hydroxyethyl group were unstable in alkaline solution, all others exhibited high resistance to alkaline treatment and peroxide bleaching.Practical implicationsThe synthesized benzothiazole-azo disperse dyes provide the opportunities to combine dyeing and alkaline reduction of polyester fabric into one bath, and combine dyeing and peroxide bleaching of cotton/polyester blend fabric into one bath.Originality/valueThe synthesized benzothiazole-azo disperse dyes help to establish short processes of polyester and polyester/cotton blend fabrics so as to reduce energy consumption and raise production efficiency.

Azo (Hydrazone) pigments: general principles

Abstract This paper presents an overview of the general chemical principles underlying the structures, synthesis and technical performance of azo pigments, the dominant chemical class of industrial organic pigments in the yellow, orange, and red shade areas, both numerically and in terms of tonnage manufactured. A description of the most significant historical features in this group of pigments is provided, starting from the discovery of the chemistry on which azo colorants are based by Griess in the mid-nineteenth century, through the commercial introduction of the most important classical azo pigments in the early twentieth century, including products known as the Hansa Yellows, β-naphthol reds, including metal salt pigments, and the diarylide yellows and oranges, to the development in the 1950s and 1960s of two classes of azo pigments that exhibit high performance, disazo condensation pigments and benzimidazolone-based azo pigments. A feature that complicates the description of the chemical structures of azo pigments is that they exist in the solid state as the ketohydrazone rather than the hydroxyazo form, in which they have been traditionally been illustrated. Numerous structural studies conducted over the years on an extensive range of azo pigments have demonstrated this feature. In this text, they are referred to throughout as azo (hydrazone) pigments. Since a common synthetic procedure is used in the manufacture of virtually all azo (hydrazone) pigments, this is discussed in some detail, including practical aspects. The procedure brings together two organic components as the fundamental starting materials, a diazo component and a coupling component. An important reason for the dominance of azo (hydrazone) pigments is that they are highly cost-effective. The syntheses generally involve low cost, commodity organic starting materials and are carried out in water as the reaction solvent, which offers obvious economic and environmental advantages. The versatility of the approach means that an immense number of products may be prepared, so that they have been adapted structurally to meet the requirements of many applications. On an industrial scale, the processes are straightforward, making use of simple, multi-purpose chemical plant. Azo pigments may be produced in virtually quantitative yields and the processes are carried out at or below ambient temperatures, thus presenting low energy requirements. Finally, provided that careful control of the reaction conditions is maintained, azo pigments may be prepared directly by an aqueous precipitation process that can optimise physical form, with control of particle size distribution, crystalline structure, and surface character. The applications of azo pigments are outlined, with more detail reserved for subsequent papers on individual products.

Synthesis of reactive dyes by the introduction of Phenyl Urea derivatives into the triazine ring and their application on different fibers

Reactive dyes are most popular class of dyeing for cotton. Currently bifunctional reactive dyes is mostly used in textiles industries. Bifunctional reactive dyes have good fastness properties, wide colour gamut, flexible application procedure. Novel bifunctional reactive dyes synthesized into the triazine ring by introducing Phenyl Urea and its derivatives. Derivatives of Phenyl Urea and (j-acid) 2-amino-5-naphthol-7-sulphonic acid were condensed with 2, 4, 6-Trichloro-1, 3, 5-triazin synthesized coupling component.4-(β-sulfatoethysulfonyl) anilin was used as a diazo component. IR spectroscopy, Visible absorption spectra and 1H NMR were used for characterization. All dyes has been examined on silk, wool and cotton. Fastness properties and exhaustion and fixation value of all synthesized dyes were evaluated. In this study it was observed that all synthesis dyes showed high exhaustion and fixation, good Wash fastness to colour, good migration and leveling dyeing.

Design of Novel Reactive Dyes Containing Cationic Groups: Mechanism and Application for Environmentally Friendly Cotton Dyeing

In this work, four novel, high fixation reactive dyes containing cationic groups were synthesized using m-aminophenyltrimethylammonium salt or 4-(ethylsulfurate sulfonyl) aniline as the diazo component, 3-(N,N-diethylamino) acetanilide or 3′-aminoacetanilide as the coupling component and m-aminophenyltrimethylammonium salt or N-(2-aminoethyl) pyridinium chloride as the cationic group. The synthesized dyes containing multiple cationic groups were characterized by FT-IR and 1H-NMR spectroscopy. The spectral properties were measured by UV-Vis absorption spectroscopy. Compared with conventional reactive dyes containing cationic groups, the synthesized dyes exhibited good water solubility upon introduction of a quaternary ammonium into the chromophore. The structural design of synthetic azo dyes allows enhanced the water solubility due to the introduction of a cationic group. The dyeing properties of the synthesized dyes to cotton fabric were explored at various temperatures and salt and alkaline concentrations. The results showed that the synthesized dyes possessed good dyeing properties with nearly 80% fixation and good color fastness on cotton (3–5) in the absence of salt. The success of the salt-free dyeing of cotton fabric with these dyes is an excellent example of environmentally friendly cotton dyeing. This study provides an important platform for the design of novel reactive dyes for cotton dyeing to reduce effluent pollution.

Synthesis and Application of Disperse Dyes Derived from 2-Aminothiophene Using Acetoacetanilide as the 1, 3-Dicarbonyl Compound

Disperse dyes derived from 2-aminothiophene diazo components was synthesized using via Gewald reaction, the intermediate were diazotized, coupled and the dyes were purified by re-crystallization. The melting points were found to span from 163°C- 209°C and spectroscopic assessment such asFT-IR spectroscopy and GC-MS were carried out to elucidate their structures. The vibrational frequency obtained for the synthesized dyes shows the characteristics absorption peaks due to stretching frequency of the NH-group in the region 3097-3365cm -1 . An absorption peak in the region 2217.8, 2221.5, 2214.0, 2206.6cm -1 was observed for dye A, A1, B and B1 due to the presence of cyano group. The IR spectra of the prepared azo dye also showed an absorption peak in the region 1438.8-1599cm -1 ascribed to V N=N, while the observed vibrational frequency in the region 1602.8-1736.9 was due to V C=O .The disperse dye A, A1, B and B1 were applied at 2% depth on polyester and nylon 6,6 fabric and gave purple, deep purple and deep pink hues with brighter and deeper shades, tinctorial strength and excellent levelness on the fabric. All the dyes show good to excellent fastness to washing on polyester fabric and fair to very good fastness to washing on nylon 6,6 fabric respectively. The remarkable degree of levelness and brightness after washing indicate good penetration and excellent affinity of the dyes to the fabric. However, dye C and dye C1 gave yellowish to deep yellowish hues with excellent tinctorial strength and brightness on the nylon 6,6 fabric. However, the light fastness ratings of the dyed polyester and nylon 6,6 fabric shows moderate to very good light fastness.

PREPARATION OF DYED AZOLIGNINS ON LINEN COTTONIN MODIFIED BY ENZYMES

The possibility of using azoreaction for obtaining colored like-cotton flax (cottonin) are evaluated in this article. For the process of disfiling (disfibering, disenchantment) enzymes Pulpzyme HC and Scourzyme L ("Novozymes A/S" (Denmark)) were applied. Diazol scarlet K was used as a diazo component. It is established that the enzymatic modification of ligno-carbohydrate complex promotes opening phenolic hydroxyls. As a result, the reactivity of flax fiber with respect to diazol alum K increases. The spectra of dyed extracted polyphenols of flax were obtained and interpreted for region of 400-700 nm. It was shown that in the spectra of extractive aromatic substances of phenolic nature for the native fiber two maxima at 420-440 nm and 500-520 were appeared nm during the azo coupling reaction. The first maximum corresponds to the compounds formed as a result of the reaction of azo combination with aromatic substances having unexpressed color (chromophore). The long-wave maximum is associated with azo lignins, where the associated and non-associated complexes of aromatic polyphenols of lignin act as the diazocomponent. It is assumed that enzymatic hydrolysis of non-cellulose polysaccharides creates stereo accessibility to the reaction groups of lignin, which is part of the structure of the ligno-carbohydrate complex of flax fiber. The dependence of the function K/S – (K/S)0 for colored flax fibers at different modification methods were obtained and interpreted. The effect of lignin unblocking in after enzymatic cottonization is confirmed. There is a significant increase in the K/S function of colored cottonin in comparison with the results for native short flax fiber. The method of spectrophotometry proved that the maximum effect of color dyeing is provided in the case of the enzymatic modification of Pulpzyme NS if excluded of the washing stage.

A Feasible Method Applied to One-Bath Process of Wool/Acrylic Blended Fabrics with Novel Heterocyclic Reactive Dyes and Application Properties of Dyed Textiles.

Reactive dyes containing cationic groups have great potentiality as novel dyes, which can be applicable to one-bath dyeing of wool/acrylic blended fabrics. In this work, four novel heterocyclic reactive dyes containing cationic groups were designed by using m-aminophenyltrimethylammonium salt or N-(2-aminoethyl) pyridinium chloride salt as cationic groups, N, N-diethyl-1,3-benzenediamine as a coupling component, 2-amino-6-methoxybenzothiazole, 2-aminobenzothiazole or 3-amino-5-nitrobenzoisothiazole as diazo components. These dyes based on benzothiazole derivative chromophores not only showed beautiful color, including blue-green and fuchsia, but also had larger tinctorial strength with a high molar extinction coefficient, further reducing the dosage of dyes to achieve same color depth. Factors affecting the dyeability on fabrics, such as pH value, dyeing temperature and dye concentration were discussed. Excellent dyeing behavior, levelling properties and good fastness on wool/acrylic blended fabric were obtained. What’ more, excellent anti-ultraviolet and antibacterial properties were obtained for textiles with these dyes. The application of these dyes with large molar extinction coefficients presents a wide range of possibilities for the further development of cleaner production and eco-friendly dyeing, even functional textiles.

Evaluation of Antibacterial Potential of New Acid Dyes Based on Substituted Aryl Amines and Amino Hydroxy Sulfonic Acid

Six newly synthesized acid dye derivatives were evaluated for their in vitro antimicrobial activity against four (04) Gram positive (Staphylococcus aureus, Staphylococcus lugdunensis, Streptococcus pneumoniae and Bacillus subtilis) and six (06) Gram negative (Pseudomonas aeruginosa, Acinetobacter baumannii, Citrobacter freundii, Klebsiella pneumoniae,Pseudomonas fluorescens and Shigella sonnei) bacterial strains. The dyes were synthesized using substituted aryl amines and substituted amino hydroxy sulfonic acid as diazo and coupling components, respectively. The antimicrobial activity was explored by Agar-Well Diffusion method using 100 mg/ml dye concentration. The results demonstrated that the dyes possess varying degrees of activities against the bacterial strains tested and the structure of the dye molecules was found to have considerable influence on their antimicrobial activity.

Evaluation of Antibacterial Potential of New Acid Dyes Based on Substituted Aryl Amines and Amino Hydroxy Sulfonic Acid

Six newly synthesized acid dye derivatives were evaluated for their in vitro antimicrobial activity against four (04) Gram positive (Staphylococcus aureus, Staphylococcus lugdunensis, Streptococcus pneumoniae and Bacillus subtilis) and six (06) Gram negative (Pseudomonas aeruginosa, Acinetobacter baumannii, Citrobacter freundii, Klebsiella pneumoniae,Pseudomonas fluorescens and Shigella sonnei) bacterial strains. The dyes were synthesized using substituted aryl amines and substituted amino hydroxy sulfonic acid as diazo and coupling components, respectively. The antimicrobial activity was explored by Agar-Well Diffusion method using 100 mg/ml dye concentration. The results demonstrated that the dyes possess varying degrees of activities against the bacterial strains tested and the structure of the dye molecules was found to have considerable influence on their antimicrobial activity.