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Pyridine and some of its derivatives have been evaluated as inhibitors for the corrosion of API‐45 steel in NACE sour solution. Amongst the various methyl and halogen substituted pyridine compounds, 2,4,6‐trimethyl pyridine is found to afford maximum protection followed by 2,6‐dimethyl pyridine, >2,4‐dimethyl pyridine, >3‐bromopyridine, >2‐methyl pyridine, 4‐methyl pyridine, 3,5‐dimethyl pyridine, >2 and 3‐chloropyridine>pyridine. These results have been discussed in the light of availability of the electron densities with the nitrogen atom of the pyridine ring. The inhibitive periormance of all the inhibitors is found to deteriorate with increase in temperature from 30 to 60°C and with passage of time. The values of heat of absorption and free energy of absorption indicates that the inhibitors have a chemical type of absorption at the metal/electrolyte interface. Polarization diagrams and shift in open circuit potential in the presence of inhibitors indicate that these compounds retard the cathodic as well as anodic reaction process.

Various polyesteramide resins are prepared in which a stoichiometric amount of hydroxy ethyl fatty acid amides (diol) are replaced by the bifunctional nicotinic acid and aisonicotinic acid derivatives of diethanolamine and triethanolamine without affecting the resin constants. The inclusion of nicotinyl and isonicotinyl residues would expect to prevent microbial growth and may also act as corrosion inhibitor.

The purpose of this paper is to discuss the synthesis of new azo disperse dyes containing pyridine ring for dyeing acetate polyester and other fibres.

Cycloaddition reaction of 3-formylchromone (Compound 1) with ethyl vinyl ether (Compound 2) afforded 3-ethoxy-4,4a-dihyro-3H,10H-pyrano[4,3-b]chromen-10-one (Compound 3). Reaction of 3 with aqueous ammonium sulphite in ethanol furnishes 3-(2-hydroxybenzoyl)pyridine (Compound 5). Compound 5 was fully characterised by spectroscopic techniques. Ten arylazo derivatives of Compound 6 have been prepared for use as dyestuffs. The effect of the nature and orientation of substituents in the diazonium component on the colour of azo dyes is discussed. Dyeing performance of the dyes on different fibres has also been assessed.

Most of the dyes showed good affinity to polyester fibres. On the other hand, polyacrylic fibres were only stained to weak shades.

No details regarding the synthesis and dyeing performance of such dyes are reported before in the literature.

Zn‐Al alloys are widely used as coatings for corrosion protection of steel. These alloys provide long‐term protection to steel in several aqueous media; however, little attention has been paid to their behaviour in acidic media. The aim of this investigation is to study the corrosion and inhibition of 90 per cent Zn‐10 per cent Al alloy in hydrochloric acid.

Pyridine and a number of its methyl‐containing derivatives were applied in controlling the corrosion of 90 per cent Zn‐10 per cent Al alloy. The inhibitive action and mechanism of these compounds were investigated by weight loss tests, linear polarisation resistance measurements, galvanostatic polarisation tests and electrochemical impedance spectroscopy.

It was found that the corrosion rate of this alloy was much higher than that of either Zn or Al alone. Pyridine and its derivatives exhibited good inhibition for the corrosion of 90 per cent Zn‐10 per cent Al alloy, their inhibition efficiency increased in the order: I < II < III < IV. Potentiodynamic polarisation studies revealed that the investigated pyridine derivatives were mixed‐type inhibitors and functioned by adsorption on reactive sites on the alloy surface through the influence of the nucleophilic nitrogen atom forming a good physical barrier to prevent access of aggressive ions to the alloy surface. This was supported by the impedance measurements which showed a change in the charge transfer resistance and double layer capacitance indicating adsorption on the alloy surface. It was shown that the introduction of the methyl group(s) into the pyridine ring enhanced the effectiveness of pyridine inhibition. The improvement was attributable to the electron‐donating tendency of this group that gives rise to the increase in the electron density at the adsorption site. All the investigated substituents showed negative values of the Hammett constant (σ), indicating their electron‐donating property. The negative value of this constant increased according to the order: I < II < III < IV, the greater the negative value of σ being consistent with the greater degree of corrosion inhibition. It also was revealed that the presence of these inhibitors increased the value of activation energy for corrosion with a ranking order that was consistent with that of their inhibition effectiveness.

The evaluated inhibitors assured significant corrosion inhibition of the Zn‐Al alloy in HCl, however, their behaviour in different acid media was ambiguous.

This paper makes significant contibution to understanding the corrosion and inhibition of one of the widely apply coatings for steel protection in one of the most widely used aqueous mineral acids in industry.

The purpose of this paper is to develop pyridine polyesteramide coatings from Linseed (Linum ussitatissimum) seeds oil for the utilisation of a sustainable resource as coating material, as well as to improve the coating properties.

Linseed oil was first converted into N,N bis 2‐hydroxyethyl linseed oil fatty amide (HELA). The resin was synthesized by the reaction of linseed oil fatty amide diol with 2,3‐pyridine di carboxylic acid to develop pyridine polyesteramide (Py‐PEA) and further treated with poly(styrene‐co‐maleic anhydride)(SMA) in different phr (part per hundred part of resin). The structural elucidation of Py‐PEA was carried out by FT‐IR, 1H‐NMR and 13C‐NMR spectral techniques. The thermal stability and curing behaviour of the resin were determined by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), respectively. The physico‐mechanical and anticorrosive properties were investigated by standard laboratory methods.

The authors developed a good anticorrosive coating material from sustainable resource. The physico‐mechanical and anticorrosive performance evaluation exhibited satisfactory results. The approach facilitated curing to occur at ambient temperature and the thermal studies revealed that Py‐PEA‐SMA‐45 might be safely used up to 140°C.

Poly(styrene‐co‐maleic anhydride) modified pyridine polyesteramide coatings showed the highest scratch hardness 3.0 kg, flexibility (1/8 inch canonical mandrel bend test) and gloss at 45° is 62‐64. Among all, Py‐PEA‐SMA 45 showed the best physico‐mechanical and chemical resistance performance. Thus, the resin may be used as an effective coating material.

The paper shows that the synthesis of polyesteramide resin from vegetable oil provides a new way to utilize a renewable resource based raw material.

This paper aims to study the inhibition effect of 2-pyridinealdazine on the corrosion of mild steel in an acidic medium. The inhibition effect was studied using weight loss, electrochemical impedance spectroscopy, and Tafel polarization measurements.

Weight loss measurements, potentiodynamic tests, electrochemical impedance spectroscopy, X-ray diffraction and spectral and conformational isomers analysis of A (E-PAA) and B (Z-PAA) were performed were investigated.

2-pyridinealdazine (PAA) acts as a good inhibitor for the corrosion of steel in 2.0 M H₃PO₄. The inhibition efficiency increases with an increase in inhibitor concentration but decreases with an increase in temperature.

This paper is intended to be added to the family of azines which are highly efficient inhibitors and can be used in the area of corrosion prevention and control.

The synthesis and chemistry of nitrogen heterocyclic azo compounds have been extensively studied. Many derivatives of this type were proved to be excellent dyes. Presents a systematic and comprehensive survey of all recently synthesised nitrogen heterocyclic azo dyes according to dyeing methods.

The purpose of this paper is to synthesise, characterise and find out properties of some new arylazopyridone disperse dyes, bearing different substituents on coupling component of the dyes.

The dyes are synthesised by diazotisation, coupling and cyclization reactions, starting from various aryldiazonium salts and different β‐diketoesters followed by condensation with cyanoacetamide. The structures of these dyes are characterised and confirmed by melting point, elemental analysis, infrared, ultraviolet‐visible spectroscopy (UV/VIS) and nuclear magnetic resonance (¹H‐NMR) data. Their absorption properties in different solvents are also investigated.

The wavelength of maximum absorptions, molar extinction coefficients are strongly dependent on the electron donating ability of the substituents on the coupling moiety. The absorption bands of these dyes move towards longer wavelength as the polarity of the solvents and electron density of substituents on the coupling moiety increase. These dyes are chromophorically strong as evidenced by molar extinction coefficient in solvents.

In this paper, four series of arylazopyridone dyes (21 dyes) are synthesised and characterised. They have not been registered in the literature previously.

Cobalt, Nickel and Copper hexaazabiphthalocyanine were prepared by the reaction of pyridine 2,3‐dicarboxylic acid anhydride, pyromillitic acid dianhydride, with urea and metal salt in presence of ammonium molybdate catalyst. The reaction is carried out in an inert solvent [nitrobenzene]. The structure of the prepared compound was confirmed by microanalytical and pectrophotometric methods. Evaluation of the highly coloured products according to international standard methods showed their suitability as excellent pigments for coating applications.

This work aims to synthesize a series of novel acyclic and/or heterocyclic systems, as precursors for dyes with potential antimicrobial activity that could be used for simultaneous dyeing and antimicrobial textile finishing. Thus, a series of novel pyridine, thiophene and pyrazolo[3,4-b]pyridine derivatives were synthesized, and their antimicrobial and textile finishing properties were studied and evaluated.

The synthesis, structure elucidation and antimicrobial activities of the newly synthesized compounds based on 4,4-dicyano-3-phenyl-but-3-enoic acid phenylamide (1) were demonstrated. The minimal inhibitory concentration in μg/mL of the compounds showed significant antimicrobial activity against most of the tested organisms. On the other hand, their spectral characteristics and fastness properties were measured and evaluated. Antimicrobial activities of the dyed fabrics in terms of inhibition zones (mm) were measured and evaluated.

A series of novel heterocyclic compounds (Schemes 1-3) were synthesized based on starting material (1). Compounds (1), 2, 4a, 8a and 9c exhibited comparable or even higher antibacterial activities than the selected standards (ampicillin), while compounds 2, 3c, 3d, 4a and 8b revealed higher antifungal activities than the selected standard (cycloheximide). On the other hand, some dyes showed high antimicrobial evaluation on the dyed fabrics (nylon 66, acetate and polyester) expressed as size (mm) of inhibition zones (Tables I-IV).

Results revealed that many hydrazo and azo derivatives were synthesized from some pyridines and thiophenes. The antimicrobial evaluation and textile finishing of the newly synthesized products revealed significant and potent values of antimicrobial activity.

All the synthesized compounds were novel and most of them exhibited higher antimicrobial activities than the selected standards antibiotics, thus are valuable for simultaneous dyeing and antimicrobial functional finishing of textile fabrics.