Micellar catalysis in the systems arylamine-diphenylamine-NO 2 −

By methods of UV and IR spectroscopy and thermogravimetry reactions of diazotizaion and azo coupling were studied in the systems of primary arylamine (p-nitro-, p-carboxy- and p-sulfoaniline)- diphenylamine -nitrite ion in water and micellar media on the basis of surfactants. The micellar catalysis effect of sodium dodecylsulfate in the micellar media was revealed. Rate of diazotization was shown to be independent of the surfactants of various types. Formation of ionic associates of azo dyes with dodecylsulfate anions in premicellar region was established and physicochemical characteristics of the associates were estimated.     

Synthesis of heterocyclic monoazo dyes derived from 1H-benzo[g]pyrazolo[3,4-b]quinoline-3-ylamine: their antimicrobial activity and their dyeing performance on various fibers

Heterocyclic monoazobenzoquinoline-based azo dyes have been derived by diazotization of 1H-benzo[g]pyrazolo[3,4-b]quinoline-3-ylamine with a variety of phenylpyrazolone-based coupling compounds. The synthesized dyes were characterized by determination of their percentage yield, by elemental analysis, and by UV?Cvisible, IR, and ¹H NMR spectroscopy. Dyeing performance on silk, wool, nylon, and polyester fibers was assessed. The fastness properties of the dyes on each fiber were moderate to excellent. The antimicrobial activity of the dyes at different concentrations were also examined, by use of the Kirby?CBauer disk diffusion method.     

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

A series of new quinazolinone based mono azo reactive dyes (D_1–10) have been prepared by subsequent diazotization of 2-phenyl-3-[4′-(4″-aminophenylsulphonamido)]phenyl-4(3H)-quinazolinone-6-sulphonic acid (C) and coupling with various 4-chloro anilino cyanurated coupling components. These dyes give purple, red, orange and yellow color shades. All the reactive dyes were characterized by their percentage yield, UV–Vis spectroscopy, elemental analysis, IR spectroscopy, ¹H NMR spectroscopy and dyeing performance on silk, wool and cotton fibres. The percentage dye bath exhaustion on different fibres has been found to be reasonably good and acceptable. The dyed fibres show moderate to very good light fastness and good to excellent washing and rubbing fastness.     

Characterization,DFT calculations and dyeing performance on polyester fabrics of some azo disperse dyes containing pyrazole ring

A number of azo pyrazole derivatives and novel Schiff bases derived from azo diamino pyrazole were synthesized. These included 4-(2-arylhydrazono)-4H-pyrazole-3,5-diamines and N³,N⁵-dibenzylidene-4-(2-arylhydrazono)-4H-pyrazole-3,5-diamines. The chemical structures of the novel azo dyes were determined using UV–visible, IR, ¹H NMR, and ¹³C NMR spectroscopy. Dyeing process and tautomerism of the aforementioned azo compounds were predicted using DFT calculations. The electronic absorption spectra in methanol were observed and compared to those computed using B3LYP/6-31G(d,p). The dyeing performance of the produced disperse dyes was examined on polyester. The degree of exhaustion and the fastness properties of the dyed samples in terms of washing, perspiration, scorch, and light fastness were assessed. Moreover, the reflectance and color strength of the synthesized dyes were measured and discussed.     

Synthesis of 1‐(p‐Sulphophenyl)‐3‐methyl‐5‐pyrazolone Based Acid Dyes and Their Applications on Leather

A new series of pyrazolone based azo acid dyes (3a–g) has been synthesized starting from 1‐(p‐sul‐phophenyl)‐3‐methyl‐5‐pyrazolone (1). The synthetic methodology included the nitrosation of p‐sulphophenyl methyl pyrazolone followed by reduction, diazotization and coupling with Naphthol AS derivatives (2a–f), in alkaline medium to yield different acid dyes. Multichromic metal complexes of these dyes (5a–f, 6a–f and 7a–f) with 3d transition metals Chromium, Iron and Copper were also synthesized. The structures of all of newly synthesized compounds were confirmed by analytical data and spectroscopic techniques. The synthesized dyes were applied on leather to assess their light fastness, wash fastness and rubbing fastness and were shown to exhibit high values of 4–5 for majority of dyes.     

Antimicrobial activities and absorption properties of disazo dyes containing imidazole and pyrazole moieties

The newly synthesized thirteen disazo dyes containing imidazole and pyrazole cycles (3a-3m) were carried out by diazotization reaction of 5-amino-4-arylazo-3-methyl-1H-pyrazoles (2a-2m) and coupling reaction with 1-methyl imidazole. Structures of synthesized azo dyes were characterized by UV–Vis, FT-IR, ¹H-NMR, elemental analysis and their solvatochromic properties were studied in DMSO, DMF, methanol, acetic acid and chloroform. In addition, the antimicrobial activities of dyes against twelve pathogenic bacteria were examined in detail and all dyes showed antimicrobial activity against different bacterial strains.     

Colorimetric studies of heterocyclic monoazo reactive dyes and their dyeing applications on cotton,silk, and wool fibers

Heterocyclic quinazolinone-based hot brand monoazo reactive dyes were obtained by diazotization of 3-(4-aminophenyl)-2-phenylquinazolin-4(3H)-one and coupling with a variety of cyanurated coupling components. All the heterocyclic hot brand monoazo reactive dyes were characterized by elemental analysis (C, H, N) and by use of spectroscopic techniques (FT-IR, UV–visible, ¹H NMR). Their performance as reactive dyes was assessed on silk, wool, and cotton fabrics. The dyes were found to give a variety of color shades with very good depth and uniformity on the fibers. The fastness of all the dyes on the fibers was moderate to excellent. Colorimetric data (L*, a*, b*, C*, H*, and K/S) of the synthesized dyes were also studied in detail.     

Can be Azo Dyes Obtained by Grinding under Solvent‐Free Conditions?

The solid‐solid reactions of some electron‐donors with sulfanilic acid in the presence of solid sodium nitrite afford azo dyes by self‐catalyzed diazotization of sulfanilic acid (2) under solvent‐free conditions with moderate yields. Also the reactions of some electron‐donors with diazotization of o‐nitroaniline (5), m‐nitroaniline (6) and p‐nitroaniline (7) in the presence of solid sodium nitrite catalyzed by p‐toluenesulfonic acid (PTSA) afford azo dyes under solvent‐free conditions in good yields. This new method totally avoids the use of acids, alkalies, and toxic and/or expensive solvents in diazotization and diazo coupling reactions.     

Design and synthesis of D-π-A fluorescent dyes based on nicotinonitrile and azobenzene derivatives

Study the synthesis and fluorescent properties of a new series of D-π-A fluorescent dyes based on nicotinonitrile and azobenzene is the main objective for this work. Reduction with Zn/HCl, diazotization with HCl/NaNO₂, and coupling using catalytic NaOH or AcONa are simple applied methods. Where, nicotinonitrile 3 was synthesized via reduction of nitro derivative 1 followed by diazotization with HCl/NaNO₂ in acetic acid. The formed benzene diazonium chloride was coupled with several activated phenols, aniline, and α-CH acids to yield the respective azo dyes 4-11 in moderate to good yield. Dyes 11a-d subjected to intermolecular cyclization with hydrazine hydrate resulted in pyrazole dyes 12-15 in moderate yield. Dyes containing pyrazole moiety or electron-withdrawing groups at the sixth position of pyridine nucleus exhibit stronger blue-green emission (λ_fl.max = 503, 507, 500, 501, 502, 493, and 514 nm) than that of the rest of compounds.     

A functionalised ionic liquid: 1-(3-chloro-2-hydroxypropyl)-3-methyl imidazolium chloride

An ionic liquid (IL) containing an appended 3-chloro-2-hydroxypropyl functionality group 1-(3-chloro-2-hydroxypropyl)-3-methyl imidazolium chloride was synthesised by the reaction of N-methyl imidazole, hydrochloric acid and epichlorohydrin. The ionic liquid showed reasonably high conductivity and heat stability up to 230°C. Its structures were characterised by FT-IR, ¹H NMR and ¹³C NMR spectra. The physical characteristics of the ionic liquid, such as conductivity and solvation abilities have been investigated. Due to its high polarity, the IL is able to dissolve many inorganic salts, and due to hydroxyl-rich microenvironment, it is able to dissolve cellulose go up to 10 (wt%). The ILs can be used for synthesising other ILs or polyelectrolyte.     

Synthesis of polymers containing azo groups in the main chain from <Emphasis Type="Italic">m</Emphasis>-phenylenediamine: Study of doping

Synthesic approach to polymers containing azo groups was developed on the basis of diazotization and azo-coupling reaction of m-phenylenediamine (m-PDA) with various ratio m-phenylenediamine-sodium nitrite. Doping of poly(azoaminophenylenes) with iodine, perchloric and hydrochloric acids was examined. Electroconductivity increases in the case of iodine to 0.2 S mol⁻¹, of perchloric acid, to 7×10⁻³ S mol⁻¹, and at the action of hydrogen chloride it is virtually unaffected. According to the ESR spectra, at the doping with iodine and perchloric acid electroconductivity enhances generally due to the mobility increase of the charge carriers (polarons).     

Synthesis and structure of trifluoromethylated arylhydrazones formed from coupling of 4-(dimethylamino)-1,1,1-trifluorobut-3-en-2-one with diazonium salts

A series of trifluoromethyl-containing arylhydrazones were prepared via a direct azo-coupling of (E)-4-(dimethylamino)-1,1,1-trifluorobut-3-en-2-one (1) with different aromatic diazonium salts. Furthermore, we also discussed the non-covalent interactions existing in the crystal structure of compound (E)-4,4,4-trifluoro-2-(2-(4-iodophenyl)hydrazono)-3-oxobutanal (3c) by the X-ray diffraction analysis.     

Enhancement of the photochromic switching speed of bithiophene azo dyes

A series of heteroaryl substituted bithiophene azo dyes in solution were irradiated with visible light to promote the azo E-Z isomerization and then the kinetics of the thermal Z-E back reaction was studied. The speed of this process is strongly influenced by the nature of the aromatic ring linked to the NN function. While thiazole bithiophene azo dyes exhibit high switching speeds between the two isomers, but limited interconversion, for benzothiazole and substituted thiadiazole bithiophene azo dyes the switching between the two photoisomers can be performed in 3 s with a significant conversion of the trans-isomer to the thermal unstable cis-isomer (19-21%) and therefore a notable variation of the visible spectrum is observed.     

2-Nitrosobenzothiazoles: useful synthons for new azobenzothiazole dyes

Novel azobenzothiazole dyes have been synthesized by condensation of 2-nitrosobenzothiazole and 6-nitro-2-nitrosobenzothiazole with aniline, anthranilic acid, 3-hydroxymethylaniline, 2-, 3- and 4-chloroaniline, 4-fluoroaniline, 4-iodoaniline or 4-nitroaniline. The new synthetic approach described is advantageous over the classic diazotization process commonly used for the preparation of related disperse dyes, since the presence of an electron-donating group at the para-position, or equivalent, of the coupling component is no more a pre-requisite for the success of the condensation reaction.     

A H, C and N NMR spectroscopic and GIAO DFT study of ethyl 5-oxo-2-phenyl-4-(2-phenylhydrazono)-4,5-dihydro-1H-pyrrole-3-carboxylate

¹⁵N-Labelled ethyl 5-oxo-2-phenyl-4-(2-phenylhydrazono)-4,5-dihydro-1H-pyrrole-3-carboxylate was synthesized by azo-coupling of diazotized aniline (using Na¹⁵NO₂ , 99% ¹⁵N) with ethyl 4,5-dihydro-5-oxo-2-phenyl-(1H)-pyrrole-3-carboxylate. The product was formed as a tautomeric hydrazone mixture as confirmed by ¹³C and ¹⁵N chemical shifts, and was obtained as a mixture of E and Z isomers according to ⁿJ(¹⁵N, ¹³C). A comparison of the ¹H NMR data with GIAO DFT calculations enabled determination of the configuration of the carboxy ester group in both isomers.     

Biosynthesis of (+)-,(-)- and (±)-tetrahydropalmatines

Specific incorporation of didehydroreticuline and reticuline into (±)- (+)-, and (-)-tetrahydropalmatines in Cocculus laurifolius and of (R)- and (S)-reticulines into (R)- and (S)-tetrahydropalmatines respectively has been demonstrated. Feeding of[l-³H, 4'-methoxy-¹⁴C]reticuline suggested that reticuline was not converted in the plants into didehydroreticuline and racemisation of optically active forms of tetrahydropalmatine did not take place via dehydrotetrahydropalmatine     

Extraction and recovery of azo dyes into an ionic liquid

The azo dyes are commonly used in the leather and textile industries as they are quite versatile in nature. However, they are neither totally utilised during the process, nor are they recovered at the end of the process. In fact, in the leather industry, typically about 10–15% of the dye is discharged with the effluent creating both environmental and economic issues. Hence, there is a need to remove the residual dye from the large volume of aqueous effluent. In this study, for the first time, azo dyes employed in the leather industry have been successfully extracted into a neutral ionic liquid, with an extraction efficiency of 98%, potentially providing a method of minimizing pollution of waste-waters. The extraction of the dye into the ionic liquid also provides a potential analytical approach to determination of these dyes.     

A spectral approach to determine location and orientation of azo dyes within surfactant aggregates

The UV–vis absorption properties of azo dyes are known to exhibit a variation with the polarity and acidity of the dye environment. The spectral properties of a series of anionic azo dyes were characterized to further probe the interaction of these dyes with two types of surfactant aggregates: (1) the spherical micelles formed in aqueous solution by alkyltrimethylammonium bromide (C_nTAB) surfactants with n = 10–16 and (2) the unilamellar vesicles spontaneously formed in water from binary mixtures of the oppositely-charged double-tailed surfactants cationic didodecyldimethylammonium bromide (DDAB) and anionic sodium dioctylsulfosuccinate (Aerosol OT or AOT). The observed dye spectra reflect the solvatochromic behavior of the dyes and suggest the location and orientation of the dye within the surfactant aggregates. Deconvolution of the overall spectra into sums of Gaussian curves more readily displays any contributions of tautomeric forms of the azo dyes resulting from intramolecular hydrogen bonding. The rich variation in UV/vis absorption properties of these anionic azo dyes supports their use as sensitive tools to explore the nanostructures of surfactant aggregates.     

Evidence for excited state intramolecular charge transfer in benzazole-based pseudo-stilbenes

Two azo compounds were obtained through the diazotization reaction of aminobenzazole derivatives and N,N-dimethylaniline using clay montmorillonite KSF as catalyst. The synthesized dyes were characterized using elemental analysis, Fourier transform infrared spectroscopy, and (13)C and (1)H NMR spectroscopy in solution. Their photophysical behavior was studied using UV-vis and steady-state fluorescence in solution. These dyes present intense absorption in the blue region. The spectral features of the azo compounds can be related to the pseudo-stilbene type as well as the E isomer of the dyes. Excitation at the absorption maxima does not produce emissive species in the excited state. However, excitation around 350 nm allowed dual emission of fluorescence, from both a locally excited (LE, short wavelength) and an intramolecular charge transfer (ICT, long wavelength) state, which was corroborated by a linear relation of the fluorescence maximum (ν(max)) versus the solvent polarity function (Δf) from the Lippert-Mataga correlation. Evidence of TICT in these dyes was discussed from the viscosity dependence of the fluorescence intensity in the ICT emission band. Theoretical calculations were also performed in order to study the geometry and charge distribution of the dyes in their ground and excited electronic states. Using DFT methods at the theoretical levels BLYP/Aug-cc-pVDZ, for geometry optimizations and frequency calculations, and B3LYP/6-311+G(2d), for single-point energy evaluations, the calculations revealed that the least energetic and most intense photon absorption leads to a very polar excited state that relaxes non-radioactively, which can be associated with photochemical isomerization.     

A_2和B_3单体重氮偶合反应制备超支化偶氮聚合物

利用A2/B3单体通过重氮偶合反应制备了超支化偶氮聚合物.利用核磁共振、红外光谱、紫外光谱和DSC热分析手段表征了聚合物的结构、光谱性能和玻璃化转变温度.合成的超支化偶氮聚合物具有很好的光响应性能,用488nm Ar+激光对超支化偶氮聚合物薄膜进行光加工,得到了规则的表面起伏光栅.