The effect of 1′,3,5,5′-tetramethyl-1′H-1,3′-bipyrazole on the corrosion of steel in 1.0 M hydrochloric acid

Abstract

The effect of some prepared compounds, namely 3,5-dimethyl-1H-pyrazole (P1), 3(5)-amino-5(3)-methylpyrazole (P2), and 1 0 ,3,5,5 0 -tetramethyl-1 0 H-1,3 0 -bipyrazole (P3), on the corrosion behaviour of steel in 1.0 M hydrochloric acid solution as corrosive medium has been investigated at 308 K using weight-loss measurement, potentiodynamic polarisation, linear polarisation, and impedance spectroscopy (EIS). Generally, inhibition efficiency of the investigated compounds was found to depend on the concentration and nature of the inhibitor. P3 was a better inhibitor than P1 and P2, and its inhibition efficiency increased with increasing concentration of inhibitor, attaining 94% above 10 -3 M. Potentiodynamic polarisation studies clearly reveal that P3 acts essentially as a cathodic inhibitor. E (%) values obtained from different methods are in reasonably good agreement. EIS measurements show an increase of transfer resistance with inhibitor concentration. Partial p-charge on atoms was calculated. Correlation between the highest occupied molecular orbital energy E HOMO and inhibition efficiencies was sought. The temperature effect on the corrosion behaviour of steel in 1.0 M HCl without and with different concentrations of inhibitor P3 was studied in the temperature range 308 to 343 K. Thermodynamic data, for example heat of adsorption (DH ads ), entropy of adsorption (DS ads ) and free energy of adsorption (DG ads ) were calculated by use of thermodynamic equations. Kinetic activation data, for example E a , DH*, DS* and pre-exponential factor, were calculated, and are discussed. The inhibiting action of P3 on the corrosion of steel in 1-10 M hydrochloric acid was also studied by weight-loss measurement. The rate constant and reaction constant were calculated for the corrosion reactions. Adsorption of P3 on the steel surface in 1.0 M HCl follows the Langmuir isotherm model.

Synthesis and applications of bipyrazole systems

“…The inhibiting effect of the bipyrazoles 12 and 93 was attributed to their adsorption at the metal-solution interface, owing to the presence of many active centers (several nitrogen atoms and many π-electrons of the pyrazole rings) for adsorption which revealed that inhibitive actions of bipyrazole compounds were mainly due to adsorption on steel surface. [170][171][172] The bipyrazole derivatives (bippyphos) 57 were applied as efficient ligands in the palladium-catalyzed C-O and C-N cross-coupling reactions of aryl halides with primary alcohols and with urea derivatives, respectively. 46,[173][174][175][176] 5,5'-Dihydroxy-4,4'-bipyrazoles 356 were reported as useful medicines for treatment of cerebral ischemia, heart diseases, gastrointestinal diseases, cancer, aging and inflammation.…”

Facile access to some new 3,3′‐bipyrazole‐ester derivatives utilizing bis‐hydrazonoyl chlorides

“…They were used as supramolecular complexes, organometallic cage‐like structures, and self‐assembling metallo‐macrocycles that are promising as catalysts, molecular mimics, molecular magnetic devices, and sensors . Furthermore, some bipyrazole derivatives were used as inhibitors for the corrosion of steel and as bidentate ligands to form ruthenium(II) complexes for hydrogenation reactions . Bipyrazoles were also reported to have antitumor, anti‐inflammatory, and cytotoxic activities and are scavengers for free radicals .…”

Corrosion Resistance of Mild Steel Coated with Orgainc Material Containing Pyrazol Moiety

“…The presence of a side chain on pyrazole showed an increase in the efficiency of the pyrazole and the longer the chain the higher the higher efficiency [21]. Several pyrazole derivatives were evaluated as steel corrosion inhibitors in our laboratory [22][23][24][25][26].…”