High fastness heterocyclic azo disperse dyes bearing ester functions

Blue monoazo disperse dyes bearing carboxylic acid ester functions have been synthesised from thiophene diazo components in the search for colorants of high fastness and reduced environmental impact. The colour properties of the dyes in solution and on polyester, as well as the fastness of the dyes when applied to polyester, are examined and rationalised in terms of dye structure.     

Synthesis and properties of some novel pyrazolone-based heterocyclic azo disperse dyes containing a fluorosulfonyl group

A series of heteroarylazo disperse dyes derived from pyrazolones and fluorosulfonyl anilines were synthesized, and their thermal and spectral properties were investigated with respect to the effect of substituents on absorption spectra, halochromism, and solvatochromism. Heteroarylazo disperse dyes, which contain a nitro group instead of a fluorosulfonyl group para to the azo group in the diazo component, were also synthesized for comparative purpose. The fluorosulfonylarylazopyrazolone dyes had absorption maxima at shorter wavelength and showed lower extinction coefficients than the nitroarylazopyrazolone dyes. The synthesized dyes also exhibited positive halochromism and solvatochromism, so the absorption bands of the dyes moved toward longer wavelengths as the acidity or polarity of the solvent increased. 4-Fluorosulfonyl-substituted dyes generally showed lower thermal stability than their 4-nitro-substituted analogs, because the lower electron-withdrawing power in the diazo components tended to decrease the polarizability and dipole interactions.     

Synthesis of isomeric azo disperse dyes of pyridobenzimidazole

Condensation of 4-(4-methoxyphenyl)-5H-pyran-2,6-dione (1) and 1,2-diaminobenzene (2) gave 3-(4-methoxyphenyl)-1-oxo-1H, 5H-pyrido [1,2-a]benzimidazole (3). When3was coupled with an aryldiazonium salt two isomeric dyes were obtained in equal proportions. These dyes were characterised as 3-(4-methoxyphenyl)-4-(arylthydrazono)-1-oxo-1H-pyrido-[1,2-a]benzimidazole (4) and 2-(arylhydrazono)-3-(4-methoxyphenyl)-1-oxo-1H-pyrido[1,2-a]benzimidazole (5) on the basis of spectral data. Their structures were confirmed also by an alternative synthetic route.     

Synthesis of benzimidazole substituted pyridone azo disperse dyes

Benzimidazole substituted couplers containing pyridone as a basic moiety were prepared by the condensation of appropriate amines with glutaconic anhydride (1). The resulting glutaconimides were coupled with diazotized arylamines to form azo disperse dyes, the fastness properties of which were evaluated.     

Synthesis and spectroscopic properties of novel phthalimide‐derived monoazo disperse dyes containing ester groups

The synthesis and spectroscopic properties of monoazo dye series, whose members consist of N‐alkylphthalimide diazo components combined with a coupling component containing two ester groups, are reported. Such colourants are potentially alkali‐clearable as a consequence not only of the presence of diester functionality on the coupler, but also through use of the base‐sensitive phthalimide system. Shortening the N‐alkyl group by removing one or two methylene units from a butyl chain made little difference to absorption properties, as would be expected given the relatively minor differences in inductive character produced. Shifts in the absorption maximum of the dyes associated with dibromination of the phthalimidylazo motif and its subsequent cyanodehalogenation were in agreement with theory and literature data for related series. Diester substitution on the coupling component brought about hypsochromism and hypochromism.     

X-ray crystal structure of disperse red 167

X-ray diffractometer data have been used to determine the crystal structure of CI Disperse Red 167, an important automotive disperse dye. The structure was solved by direct methods and refined by least squares to R = 0.0442 for 1115 independent reflections. This monoazo dye possesses a planar azobenzene skeleton, as the dihedral angle between the planes made by the two aromatic rings is 1.5°. The non-bonding distance between the hydrogen atom of the acetamido group and azo nitrogen N(1) is well within the expected distance for intramolecular hydrogen bonding. Interestingly, the chloro and acetamido groups lie on the same side of the azo bond, and each unit cell of this dye contains 8 molecules.     

Colour fastness properties of alkali-clearable azo disperse dyes containing a fluoro-sulphonyl group

The colour fastness properties of alkali-clearable azo disperse dyes containing a fluorosulphonyl group have been investigated. In particular, the colour fastness properties of alkali-cleared poly(ethyleneterephthalate) were compared with those of conventional reduction-cleared poly(ethyleneterephthalate). Specifically, 4-aminoazobenzene dyes containing a nitro group in place of the fluorosulphonyl group in the 4'-position were synthesised in order to compare their fastness properties on poly(ethyleneterephthalate) with those of the 4'-fluorosulphonyl analogues.     

Synthesis of isomeric azo disperse dyes of pyridobenzimidazole—part II

3-(4-Methoxyphenyl)-1-oxo-1H,5H-pyrido[1,2-a]benzimidazole(1) was subjected to demethylation generating additional nucleophilic centres on the 3-phenyl ring. However, on coupling with an aryldiazonium salt it gave a mixture of a pair of positionally isomeric azo dyes with coupling in the pyridone ring. Compound 1 was converted to an acetylated Pyridobenzimidazole derivative, which, on azo-coupling gave a pair of positionally isomeric acetylated pyridobenzimidazole dyes. The dyes were tested on polyamide (PA) and polyester (PES) fibres.     

Synthesis and single crystal structure of an AFX-type magnesium aluminophosphate

SAPO-56 (framework type: AFX) has a framework topology slightly different from that of zeolite chabazite (framework type: CHA). While metal substituted aluminophosphate chabazite analogues can be prepared under a variety of experimental conditions with dozens of different amines, the synthesis of SAPO-56 type materials has been more difficult, particularly in non-SAPO compositions. Prior to this work, the growth of large crystals of the AFX-type materials suitable for single crystal diffraction has not been possible in any composition. Here we report the synthesis and single crystal structure of a magnesium aluminophosphate denoted as MAPO-AFX. This represents the first time that the AFX-type topology is made in a metal aluminophosphate composition. The synthesis was accomplished with a novel polyether diamine as the structure-directing agent. Crystal data for MAPO-AFX, (RH₂)_0.10(NH₄)_0.45[Mg_0.65Al_1.35(PO₄)₂](H₂O) where R=O[CH₂CH₂O(CH₂)₃NH₂]₂, space group P-31c (#163), Z=12, MoK radiation, 2θ_max=50°, a=13.8425(6) Å, c=20.204(1) Å, V=3352.7(3) ų, refinement on F², R(F)=7.94% for 131 parameters and 1218 unique reflections with I>2.0σ(I).     

Synthesis of aromatic-aliphatic polyamides containing azo linkage

Summary Two inherently coloured polyamides containing aromatic azo unit in their backbone were synthesised from 4,4-diaminoazobenzene (1) and two aliphatic dicarboxylic acid chlorides (2a, 2b) using N-methyl pyrrolidone (NMP) and N,N-dimethyl acetamide (DMAc) as solvents by the low temperature solution polycondensation method. The polymers were characterised by inherent viscosity, solubility, infra-red and UV-visible spectroscopy. Thermogravimetric analysis of the polymers was carried out to study polymer stability.     

Synthesis and dyeing properties of novel disperse dyes. Part 2: Pyrazole disperse dye derivatives

Several new disperse dyes derived from thiosemicarbazides and acetoacetanilide have been synthesised. The dye structures were ascertained by chemical analysis and infrared measurements. Prepared dyes were used for dyeing nylon fabric by the exhaustion method. The colour strengths and dye fixation on the fabric were also determined. The results suggest a practical significance.     

Synthesis and application of thermosensitive microcapsules containing azo groups

In view of applying thermolabile microcapsules with azo groups as thermosensitive sites it was necessary to study the preparation and the thermal behaviour of two reactive, symmetrical azo monomer-compounds and model compounds. They are thermally and photochemically instable and the kinetics of their decomposition is of first order, comparable to that of AIBN. Azo group-containing polyamides and polyureas were prepared by interfacial polycondensation reaction from ethylendiamine, 1,6-hexamethylenediamine, diethylenetriamine and azo monomer-compounds. These polymers were used to prepare thermosensitive microcapsules. Favourable conditions were found to obtain microcapsules of uniform size, in a high yield, and with good properties in thermo-transfer-print.     

Synthesis of water soluble sulfonated polyaniline and determination of crystal structure

A polyaniline (PANI) was synthesized by the oxidative polymerization using ammonium persulfate as an oxidizing agent. The PANI was then stirred with excess fuming sulfuric acid at room temperature for 6 h to obtain water soluble sulfonated polyaniline (SPANI). The degree of sulfonation was found to be 93–94% from the Fourier transform infrared (FTIR) and elemental analysis. The solubility of the SPANI in water was 1.25 g/L at room temperature and appeared as a green color solution. Conductivity of the PANI was decreased after sulfonation. A proliferation of hydrophilic nature of the PANI after sulfonation was observed from the water contact angle measurement. From the UV analysis, it was revealed that the energies required for the π–π* and bipolaron/polaron transitions are less and the intensity of these transitions are lower in SPANI compared to those of PANI. A detailed study on the crystal structures of PANI and SPANI were accomplished from the powder X‐ray diffraction analysis. The SPANI exhibited a more ordered structure having a higher degree of crystallinity and crystallite sizes with an increased unit cell volume compared to the PANI. After sulfonation the morphology of PANI was transformed from a rod‐like shape to a flat‐plate shape. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Surface potential measurements of Langmuir films of azo dye/liquid crystal mixtures

Two-component films of a non-amphiphilic azo dye and a liquid crystal with strongly polar –CN group were studied at an air–water interface on the basis of the surface potential–mean molecular area dependence recorded simultaneously with the surface pressure–mean molecular area isotherm. Additionally, the morphology of the films was monitored with the aid of Brewster angle microscope. A conventional Langmuir technique was used to form dye/liquid crystal films during reduction and expansion of an area occupied by the molecules. From the surface potential value, the effective dipole moment in the first monolayer formed on the water was calculated. Moreover, the number of molecules with dipole moments directed from the water to the air with respect to those directed towards water was estimated. The influence of the two components' miscibilities upon the surface potential after addition of the dye to the liquid crystal was determined.     

Synthesis and X-ray single crystal structure analysis of an inorganic nucleoside analog

The inorganic nucleoside analog [Boc-aeg{Cu(pda)py-Ac}-OMe] (3) is prepared and fully characterized. The X-ray single crystal analysis reveals that 3 assembles by apical Cu–O bonds into a coordination polymer, with short Cu–Cu distances of 5.32 and 5.78 Å. The solid state structure of 3 is in accordance with an isotactic structural model for charge neutral inorganic nucleic acids analogs. Aeg = (2-aminoethyl)glycine, py-Ac = 4-acetyl pyridine, pda = pyridine-2,6-dicarboxylic acid.     

Relationship between photofading and chemical structure of disperse azo dyes on nylon fabric†

The initial rates of photofading for 30 disperse azo dyes on nylon fabric upon exposure to a carbon arc in air have been analysed by formulating a kinetic equation that describes azo scission via the disproportionation reactions and intramolecular H‐transfer by two kinds of hydrazinyl radicals and the conversion of a nitro group to a nitroso group via the disproportionation reaction of nitrosyl hydroxide radicals. The five reaction rate constants are discussed in terms of the heats of reaction by calculating the heats of formation for the reactants, intermediates and products of each reaction using the PM5 method. Phenylazo‐ and thiazoleazo‐N,N‐substituted anilines and phenylazo‐pyridones exhibited large rate constants of multiple terms, while phenylazo‐phenols had the highest light fastness and very small rate constants for the disproportionation reactions of hydrazinyl radicals. Photofading on nylon fabric was primarily controlled by the thermal reactions of photo‐induced monohydrogenated dye radicals, which occurred via one or two primary multiple routes.     

Electrochemical method for quantitative determination of trace amounts of disperse dye in wastewater

The electrochemical behaviour of Disperse Red 13 dye at a glassy carbon electrode was investigated in both organic and aqueous organic mixtures. Best results were obtained in N,N‐dimethylformamide/Britton–Robinson buffer (1:1, v/v), which displays a well‐defined peak at ‐0.40 V (vs Ag/AgCl) owing to reduction of the protonated nitro group. This method can be successfully applied to the electroanalytical determination of Disperse Red 13 in a very simple and inexpensive way. All the differential pulse voltammetry parameters were optimised by using a glassy carbon electrode modified with poly(glutamic acid) films. The targeted analytical method presented a linear response from Disperse Red 13 concentrations between 2.5 × 10^?7 and 3 × 10^?6 mol l^?1 (r = 0.997), with a detection limit of 1.5 × 10^?8 mol l^?1 and recoveries of 89.7–95.10% in water samples. Disperse Red 13 was successfully determined in textile industry wastewater by means of the proposed method after pre‐extraction in a solid‐phase extraction cartridge.     

Synthesis of azo benzo[b]thiophene derivatives and their application as disperse dyes

2-Amino-4,5,6,7-tetrahydrobenzo[b]thiophene-3-carbonitrile and ethyl-2-amino-4,5,6,7-tetrahydrobenzo[b]thiophene-3-carboxylate were synthesised by reaction of cyclohexanone and sulphur with malononitrile and ethyl cyanoacetate respectively. These 2-aminothiophene derivatives were diazotised and coupled with a variety of coupling components to give azo dyes. The spectral properties of these dyes are reported. The dyes had generally good colouration and fastness properties on polyester.     

Coloration properties and clearability of phthalimide‐derived monoazo disperse dyes containing ester groups

The coloration properties and clearability of disperse dyes prepared from phthalimide‐derived diazo components and a coupling component containing two carboxylic acid ester groups have been investigated. Members of the series featured C₂–C₄ alkyl substituents on their phthalimidyl nitrogen atom. The nature of the N‐alkyl group made no consistent difference to dye uptake on polyester. No correlation was found between percentage exhaustion and calculated solubility parameters. Wash fastness was extremely good. Comparison with analogues indicated that the diester motif was of significant extra benefit to wash fastness for phthalimide‐derived dyes, but did not increase photostability above the lower range of commercial acceptability. Clearability was compared with that of dyes lacking one or both hydrolysable structural features, as well as with that of some industrial dyes. The novel dyes exhibited a greater tendency to be solubilised, consistent with hydrolysis of their ester and/or phthalimide functionalities.     

Technical properties and photofading of disperse heterocyclic azo dyes

A series of heter acyclic azo dyes derived from aminophenyl-benzothiazoles and substituted dialkylanilines was prepared and tested on polyamide and polyester. The overall properties were satisfactory and compared favourably with related dyes previously described.

Several correlations between structure and physical, spectroscopic (VIS and NMR) and fastness properties were found. An investigation of the photofading of the dyes on substrates as a function of time, checked with colourimetric techniques, proved a close time-dependent feature for colour parameters.