Search results

This 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.

The 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.

Increasing 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.

The 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.

The 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.

To synthesize some new heterocyclic disperse azo dyes and their utilization in textile printing.

To prepare 1‐cayno‐1‐substituted aryl azo‐2‐methyl benzothiazole by the reaction of 2‐aminothiophenol with malononitrile and the end product coupled with different diazonium salts. The prepared dyestuffs are established using element analysis, IR measurements, ¹H‐NMR and Mass spectra. Printing pastes containing the prepared dyestuffs and a thickener were used for printing polyester and/or nylon 6 using either transfer printing or traditional printing.

New selected arylazo cyanomethyl benzothiazole dyes were obtained from the reaction of diazotized aniline derivatives with 2‐cyanomethyl benzothiazole as a coupling component. The suitability of the prepared dyestuffs for either heat transfer printing or traditional printing on polyester and nylon 6 fabrics has been investigated. The prints obtained from dyes containing non polar groups which have sublimation properties possess high colour strength as well as good overall fastness properties if compared to those obtained using dyes containing polar groups.

The new heterocyclic disperse azo dyes were prepared from 2‐cyanomethylbenzothiazole and were utilized in preparing pastes for textile printing to print polyester and nylon 6 fabrics. In addition, the variation in substituents on the synthesized dyes could also be studied.

The method of synthesis of the new dyestuffs provides a simple and practical solution to prepare some new heterocyclic disperse azo dyes with low molecular weight, suitable for sublimation in heat transfer printing methods.

The methods for synthesis of the new heterocyclic disperse azo dyes are simple. These dyestuffs could be used in textile printing of polyester and nylon 6 on an industrial scale.

The purpose of this study, 3-aminopyridine, 8-aminoquinoline and some new synthesized 2-aminobenzothiazoles were diazotized with nitrosyl sulfuric acid and subsequently coupled with 5-chloro-8-hydroxy quinoline to synthesize the corresponding heteroarylazo dyes 6–13.

The structures of dyes were characterized by mass, Fourier transform infra red, ¹H proton nuclear magnetic resonance and ultra violet-visible spectroscopic techniques. Absorption spectra of the dyes were measured in acetic acid, ethanol, chloroform, acetonitrile, dimethyl formamide and dimethyl sulfoxide and correlated with the nature of the solvents and substituents. The effects of varying pH on the absorption wavelengths of the azo dyes were also studied. In addition, the acidity constants (pKa) of the dyes were determined using the spectrophotometric method in an ethanol-water mixture (80:20, v/v) at 20–23°C. Besides, density functional theory (DFT) calculations were carried out to compare the energies of proposed azo and hydrazone tautomers of the dyes.

The results showed that the withdrawing chloro groups on the diazo moiety have significant influence (red shift) on the electron absorption spectra of these dyes. In addition, introducing electron withdrawing chloro groups into the benzothiazoles moiety increased the acidic character of dyes.

The synthesized 7-hetroarylazo-5-chloro-8-hydroxy quinoline dyes are new members in the 8-hydroxyquinoline azo dyes family, where very few details regarding the synthesis of such dyes are reported before in the literature. They are unique in terms of synthesis, spectral properties and DFT calculations.

In response to a plea to eliminate zinc dialkyldithiophosphate (ZDDP) in engine oil, or at least reduce it to 0.05 per cent, unfortunately no new antiwear additives to reduce ZDDP have been found until now. The aim of this paper, therefore, is to resolve these problems by designing a novel benzothiazole compound and using it as a performance‐enhancing agent for ZDDP.

A benzothiazole derivative containing dialkyldithiocarbamate (BSD) was synthesized. The antiwear and load‐carrying properties of the additive and their synergistic effects with ZDDP were evaluated by a four‐ball tester.

The additive BSD possessed good load‐carrying capacity, and exhibits good synergistic antiwear and load‐carrying properties with ZDDP. The tribo‐chemical mechanism was also proposed.

The paper provides a good ashless additive which has good antiwear properties, and fulfils an identified resources need, which can offer practical help in industrial applications and also to an individual starting out on an academic career.

This paper aims to study inhibitory effect of 4-aminothiophenol on the corrosion of mild steel (MS) in 0.5 M HCl.

In this study, electrochemical experiments, quantum chemical calculations, potentiodynamic measurements, linear polarization resistance and scanning electron microscopy were used.

The experimental results suggest that this compound is efficient corrosion inhibitor and the inhibition efficiencies increase with increasing their (from 0.5 to 10.0 mM.) concentrations. This reveals that inhibitive actions of inhibitors were mainly due to adsorption on mild steel surface. The adsorption of these inhibitors was found to obey Langmuir adsorption model. The computed quantum chemical features show good correlation with empirical inhibition efficiencies.

The 4-aminothiophenol is suitable inhibitor for application in closed-circuit systems against corrosion. The study is original and has great impact in industrial area. The obtained theoretical results have been adapted with the experimental data.

This study aims to represent a successful simple method for the synthesis of some novel dyes based on thiazole derivatives and their applications in textile printing.

2-(benzo[d]thiazol-2-ylmethyl)thiazol-4(5H)-one compound is prepared by convention heating and microwave technique then used as a coupling agent, which reacts with different diazonium Salt to form diazo dyes.

The synthesized diazo dyes are confirmed via spectral data (IR,1H-NMR, 13C-NMR and Mass spectra). The dyes are used to print polyester fabric. The obtained results clarified that the prints have good color strength, brilliant color and highly durable antibacterial activity.

The authors designed efficient synthesis for some novel thiazolone dyes. The novel procedure features short-reaction time, very good yields and a simple workup. The authors studied the antibacterial activity and their application in printing polyester fabrics.

Evaluation of uracil and/or benzothiazol derivatives as antioxidants in natural rubber mixes.

Cyanoacetylurea 1, as a precursor, was prepared at a good yield from widely available, low‐cost chemicals. Compound 1 was treated with triethylorthoformate and amine derivatives in one pot reaction affording the target uracil derivative 3. Replacement of the cyano group in 1 by benzothiazol led to obtaining the interesting N‐hydroxy uracils containing benzothiazole moiety 5 at a good yield. Some of the compounds prepared was selected and were evaluated as antioxidants in natural rubber mixes. The rheometric characteristic of the compounded rubber and the physico‐mechanical properties of the vulcanizates were determined.

The cure rate index, tensile strength and modulus increased while the equilibrium swelling decreased, i.e. compound 5 behaved as a secondary accelerator. The rubber vulcanizates were subjected to thermal oxidative ageing at 90°C for up to seven days. It has been found that uracil and/or benzothiazol derivatives can protect natural rubber vulcanizates against oxidative deterioration.

The compounds prepareds were difficult to dissolve, they needed solvents with high boiling points, e.g. DMF, DMSO to be dissolved and even then they are not completely dissolved.

Uracil and or benzothiazol derivatives have many industrial applications.

The new compounds were prepared from very cheap and widely available chemicals. The compounds synthesised showed good antioxidant behaviour in comparison with the commercial antioxidant (phenyl‐β‐naphthyl amine) industrially used.

Cu(II) complexes with some hydroxy azo compounds derived from thiazole and benzothiazole have been synthesized. The structures of the complexes are inferred from data of elemental analysis, electronic, IR and H¹ NMR spectra. It is found that the Cu(II) coordinated to ligands through the nitrogen atom of azo group and hetero ring. This coordination lead to lower the energy of CT transition of ligands. The effect of molecular structure of the ligands and nature of the metal ion on complex formation are also examined. The free energy and stability constant of complexes formed in solution have been determined spectrophotometrically. Thiazole azo dyes were found to behave as an inhibitor with respect to the corrosion of copper in acidic solutions.

The purpose of this paper is investigate the inhibition efficiency of three similar bi-cyclic organic compounds, namely, benzimidazole (BI), benzotriazole (BTAH) and benzothiazole (BTH) on carbon steel in 1 M hydrochloric acid (HCl) solution. Organic inhibitors are widely used to protect metals in acidic media. Among abundant suggestions for acid corrosion inhibitors, azole compounds have gained attention.

The inhibition efficiency of the three organic compounds was investigated using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS).

Superiorities of BTH and BTAH corrosion inhibitors were shown by EIS data and polarization curves. Moreover, the results revealed that BTAH and BTH can function as effective mixed-type adsorptive inhibitors, whereas no inhibition behavior was observed for BI. Both BTAH and BTH obeyed Longmuir adsorption isotherm. The results obtained from this isotherm showed that both inhibitors adsorbed on the specimen surface physically and chemically. The difference in inhibition efficiencies of BTAH, BTH and BI was related to the presence of nitrogen and sulfur hetero atoms on their molecular structures.

This study evaluated inhibition efficiency of BI, BTAH and BTH using electrochemical methods. In addition, the study attempted to find inhibition mechanism of the inhibitors and to find modes of adsorption of the inhibitors, correlating effects of heteroatoms and inhibition efficiency.

The aim of the paper is to compare consumer acceptance, sensory analysis and volatile compounds of caiman meat with regard to surubí fish and chicken meat.

Caiman tail, chicken thigh and surubí meats' cuts were cooked in a pan with little oil and salt. The affective tests of acceptance (9-points hedonic scale) and preference ranking were evaluated by 80 consumers. Sensory analysis carried out by eight trained panelists described attributes' intensities on an unstructured linear scale (0–150 mm). Volatile compounds were analysed by solid-phase micro-extraction and gas chromatography/mass spectrometry GC–MS.

Caiman meat had good acceptance values of 6–7 (“like slightly” to “like moderately”), being similarly preferred to surubí but less than chicken. The ratings of bitterness, hardness, fibrous appearance, fibrous texture and cohesiveness were higher and raw colour, characteristic flavour and oiliness were lower in caiman's meat than in the others. Caiman meat had lower juiciness than chicken but similar to surubí. Caiman showed lower levels of aldehydes than chicken, lower level of hydrocarbons and higher levels of acids and esters than the other meats. Alcohols, mainly found in caiman and chicken meat, were positively associated to aroma acceptance. Hydrocarbons, mainly found in surubí meat, were positively associated with the characteristic flavour and negatively correlated with aroma acceptance. Volatile composition of meats was related to their sensory attributes and consumer acceptance.

Given that caiman meat showed similar acceptance and preference to that of surubí, it could be considered a good quality meat, helping promote current programmes of sustainable use of natural resources.