Araceli Espinoza-Vázquez

Multicomponent Click Synthesis of New 1,2,3-Triazole Derivatives of Pyrimidine Nucleobases: Promising Acidic Corrosion Inhibitors for Steel

A series of new mono-1,2,3-triazole derivatives of pyrimidine nucleobases were synthesized by one-pot copper(I)-catalyzed 1,3-dipolar cycloaddition reactions between N-1-propargyluracil and thymine, sodium azide and several benzyl halides. The desired heterocyclic compounds were obtained in good yields and characterized by NMR, IR, and high resolution mass spectrometry. These compounds were investigated as corrosion inhibitors for steel in 1 M HCl solution, using electrochemical impedance spectroscopy (EIS) technique. The results indicate that these heterocyclic compounds are promising acidic corrosion inhibitors for steel.

Synthesis of New 1,2,3-Triazole Derivatives of Uracil and Thymine with Potential Inhibitory Activity against Acidic Corrosion of Steels

Ten 1,4-disubstituted 1,2,3-triazoles were synthesized from one of 1-(azido-methyl)benzene, 1-(azidomethyl)-4-fluorobenzene, 1-(azidomethyl)-4-chlorobenzene, 1-(azidomethyl)-4-bromobenzene or 1-(azidomethyl)-4-iodobenzene, generated in situ from sodium azide and the corresponding benzyl halide, and dipropargyl uracil or dipropargyl thymine. Optimal experimental conditions were established for the conventional click chemistry. The corrosion inhibiting properties of some of these compounds, which were determined by means of an electrochemical technique, are also presented.

Multicomponent Synthesis and Evaluation of New 1,2,3-Triazole Derivatives of Dihydropyrimidinones as Acidic Corrosion Inhibitors for Steel.

An efficient one-pot synthesis of 1,2,3-triazole derivatives of dihydropyrimidinones has been developed using two multicomponent reactions. The aldehyde-1,2,3-triazoles were obtained in good yields from in situ-generated organic azides and O-propargylbenzaldehyde. The target heterocycles were synthesized through the Biginelli reaction in which the aldehyde-1,2,3-triazoles reacted with ethyl acetoacetate and urea in the presence of Ce(OTf)3 as the catalyst. The corrosion inhibition of steel grade API 5 L X52 in 1 M HCl by the synthesized compounds was investigated using the electrochemical impedance spectroscopy technique. The measurements revealed that these heterocycles are promising candidates to inhibit acidic corrosion of steel.

Caffeine and nicotine in 3% NaCl solution with CO2 as corrosion inhibitors for low carbon steel

The electrochemical impedance technique was employed to evaluate the inhibitory activity of caffeine and nicotine with a concentration range from 0 to 50 ppm under static and turbulent flows (100, 500 and 1000 rpm) on the corrosion of AISI 1018 low-carbon steel immersed in NaCl + CO2. The inhibitor efficiency (η) increased with increasing inhibitor concentration, as corroborated by EIS. However, this effectiveness was even present at low inhibitor concentration, indicating that these compounds are good corrosion inhibitors under static conditions (η > 90% for caffeine and >80% for nicotine). Thermodynamics analysis using the Langmuir model demonstrated that the adsorption is by physisorption. Surface analysis (SEM-EDS) also corroborated that the corrosion inhibition occurs due to the adsorption of caffeine or nicotine molecules at the metal–solution surface. The influence of immersion time on η was also assessed for the best concentration, demonstrating that even when the η of both inhibitors diminished nearly linearly as a function of time, they provide adequate protection (η > 80%) to the steel substrate even after 336 hours of exposure to this highly corrosive medium, with the inhibition decreasing with further exposure.

Electrochemical Impedance Evaluation of Uracil and Thymine Pyrimidine Derivatives and its Nucleosides Compounds as a Non-Toxic Corrosion Inhibitors of Steels in 1M HCl

a Universidad Autonoma Metropolitana-Azcapotzalco, Departamento de Ciencias Basicas, Av. San Pablo 180. CP. 02200, Mexico D. F., Mexico b Universidad Autonoma Metropolitana-Azcapotzalco, Departamento de Materiales, Av. San Pablo 180. CP. 02200, Mexico D. F., Mexico c Universidad Autonoma del Estado de Mexico (UAEM), Centro Universitario Valle de Mexico). Blvd. Universitario S/N, Atizapan de Zaragoza, Mexico, C.P. 54500.

Electrochemical assessment of phenol and triazoles derived from phenol (BPT) on API 5L X52 steel immersed in 1 M HCl

The corrosion inhibition of phenol triazoles was tested with several halogens by means of electrochemical impedance and potentiodynamic polarization. We observed the importance of the 1,2,3-triazole ring in the chemical structure because significant inhibition efficiencies (η) > 90% were achieved at low concentrations with the different halogens. These compounds have a physisorption-type adsorption process, in accordance with the Langmuir model. For long immersion times, the organic inhibitor BPTI showed good corrosion protection during 504 hours of immersion with η > 80%. Furthermore, the hydrodynamic conditions proved that organic molecules experience a desorption process related to the different rotation velocities employed. Finally, it was demonstrated by SEM that the corrosion velocity is diminished when using the BPTI inhibitor at 50 ppm.

Synthesis of 1,2,3-triazoles in the presence of mixed Mg/Fe oxides and their evaluation as corrosion inhibitors of API 5L X70 steel submerged in HCl

In this work, the catalytic capacity of a Mg/Fe layered double hydroxide (LDH) and its mixed oxides to perform Huisgen cycloaddition was studied. The catalytic process was performed in the presence of sodium ascorbate, which was determinant for the success of the 1,3-cycloaddition. The obtained triazoles were evaluated as corrosion inhibitors using electrochemical impedance spectroscopy under static conditions, showing an inhibition efficiency higher than 95% at 50 ppm for some of the triazoles studied. According to the Langmuir isotherm, all the compounds synthesized and analysed exhibit a chemisorption process. Finally, the corrosion process when submerging a steel bar in 1 M HCl was studied using SEM-EDS. This experiment showed that the corrosion process decreases considerably in the presence of 50 ppm of the organic inhibitor.