Corrosion inhibition of mild steel by some pyrazole derivatives in aqueous HCI solutions

The inhibitive properties of pyrazole derivatives (1-9) for corrosion of mild steel in 0.5 M HCl solution have been evaluated. For some derivatives the efficiency value is 97%. Langmuir absorption isotherm and Hammett substitution constants for these derivatives are in agreement with the galvanostatic measurements. Greater inhibition has been obtained with electronwithdrawing substiuents than with electron-donating ones.