Ayhan Yıldırım

Long-Chain Alkylthia-Benzimidazoles as Corrosion Inhibitors for Carbon Steel in H2SO4 Solution

Abstract A series of long-chain N-arylundecanamides containing benzimidazole thioethers (2a–e) were synthesized and characterized by FT IR, 1H NMR, and elemental analysis. The corrosion inhibitory properties of these compounds on cold rolled low carbon steel metal coupons were investigated by weight loss measurements in acidic media. Surface characterization studies of the metal coupons used were performed by contact angle measurements using the sessile-drop method. In addition, the 3D image of the metal surface was measured using an optical profilometer. The results obtained from these analyses showed that almost all of the tested compounds between 25–150-ppm concentrations in acidic media are good to excellent corrosion inhibitors with the values of percentage inhibition efficiency (η) = 77–99%. Supplemental materials are available for this article. Go to the publishers online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file. GRAPHICAL ABSTRACT

Sustainable synthetic approaches using [C16Im][Oxa] as a flexible organocatalyst and DFT studies toward 3,4-dihydropyrimidinones and benzoxazines

Easily accessible 1-hexadecyl-1H-imidazol-3-ium oxalate is highly efficient Brønsted type acidic catalyst for the selected multicomponent one-pot reactions. The short reaction times, easy workup procedures, and green metal-free conditions for the reactions make the protocols more advantageous. Further reactions proceeded smoothly in good to excellent yields with high purity. To investigate mechanism of the multicomponent reactions, DFT calculations were performed.Graphical abstract

Synthesis and Surface Characterization Studies of Polyether-Linked Symmetric Higher Sulfanyl-1,3,4-Oxadiazoles

GRAPHICAL ABSTRACT Abstract The synthesis and the characterization of a series of novel symmetric double length alkyl-chained sulfanyl-1,3,4-oxadiazoles functionalized with a polyether head group are reported. In addition, surface characterization studies were conducted on the metal surface of these synthesized compounds. The metal surfaces were characterized by contact angle measurements via the sessile-drop method, and 3D images of the metal surface were obtained using an optical profilometer. The surface studies showed that the inhibitor molecule increases the hydrophobic character and decreases the wettability of the metal surface.

Evaluation of the corrosion inhibiting efficacy of a newly synthesized nitrone against St37 steel corrosion in acidic medium: Experimental and theoretical approaches

A novel amphiphilic nitrone, N-phenyl-1-(4-((11-(pyridin-1-ium-1yl) undecanoyl) oxy)phenyl)methanimine oxide bromide (NP-1-4-11-PUOPMOB) has been synthesized from a fatty acid derivative as a starting material. Structural characterization of the new compound has been realized by spectroscopic techniques (FTIR, 1H NMR, and 13C NMR). The corrosion inhibition effect of the compound for St37 steel corrosion in 1 M HCl medium has been investigated using experimental (weight loss, electrochemical impedance spectroscopy, potentiodynamic polarization, dynamic electrochemical impedance spectroscopy) and theoretical approaches complemented by surface morphological examination using energy dispersive X-ray spectroscopy, scanning electron microscope, and atomic force spectroscopy. Results from both chemical and electrochemical techniques reveal that the presence of the nitrone in the acid solution impedes St37 steel corrosion. The inhibition efficiency obtained at 125 ppm and 150 ppm concentrations for all methods is found to be over 90%. NP-1-4-11-PUOPMOB behaves as a mixed type corrosion inhibitor according to the potentiodynamic polarization studies. The adsorption of NP-1-4-11-PUOPMOB molecules onto the metal surface follows Langmuir adsorption isotherm and the calculated Kads (equilibrium constant of the adsorption process) value reflects strong interaction. There is evidence of NP-1-4-11-PUOPMOB adsorption on the metal surface from SEM, EDAX, and AFM studies. Experimental and theoretical results are in good agreement.

Synthesis of 2,3-Dihydroxypropylsulfanyl Derivative Nonionic Surfactants and Their Inhibition Activities Against Metal Corrosion in Acidic Media

Metallic corrosion is one of the most important problem in various industrial fields. One of the most effective methods to deal with metallic corrosion is to design and use appropriate organic corrosion inhibitors. In the present study, various amide-based, sulfur-containing nonionic surfactants were synthesized and characterized by spectroscopic methods. The corrosion inhibition properties of these synthesized compounds were investigated. For this purpose, mild steel coupons were immersed for 24 hours at room temperature in 1 M HCl containing different concentrations of inhibitor according to the ASTM NACE / ASTMG31-12a standart method . As a result of these corrosion tests, the synthesized compounds exhibited very good inhibitory properties (76.58-93.74 IE %). Surface characterization studies were also performed for the metal coupons to support the obtained corrosion inhibition efficiency results.

Synthesis of Aromatic Structured Di-cationic Surfactants Used as Inhibitors Against Corrosion of Carbon Steel in Acidic Medium

In this study, three aromatic-structured di-cationic surfactants with different length carbon chains were synthesized and inhibition efficiencies against metal corrosion in 1.0 M HCl solution were investigated. Corrosion inhibition efficiencies of di-cationic surfactants that structurally illuminated by spectroscopic methods (FT-IR and NMR) were determined in acidic media by gravimetric method based on weight loss in metal coupons. Corrosion tests resulted in good inhibition efficiencies (90.40% - 96.85%) against metallic corrosion at different concentrations of inhibitors. By using the weight loss values, corrosion rates were also calculated in the inhibited and uninhibited medium. Finally, images of metal surfaces were obtained using scanning electron microscopy to support the obtained corrosion inhibition effect results.

Metallic magnesium: an efficient catalyst toward N-aryl and N-alkyl substituted amides directly from aliphatic carboxylic acids

An efficient and inexpensive procedure for direct conversion of aliphatic carboxylic acids into amides has been developed using anilines or aliphatic amines and Mg(0) as catalyst in toluene. The amides were obtained by single crystallization in moderate to excellent yields with high purity.Graphical Abstract