الفهرس 
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Abstract
The aim of the present work is to study the reactivity of some pharmaceutical compound as corrosion inhibitors for tim in sodium solution. The thesis comprises three main chapters.
The first chapter:
Deals with the introduction which includes corrosion theories types of corrosion cost of corrosion importance of corrosion corrosion protection literature survey corrosion behavior of tin aqueous environment and aim of the present work.
The second chapter :
Desls with the experimental techniques which include the chemical composition of the investigated material and preparation of the used solutions
Also the experimental technique contains the instruments and the procedures used for the corrosion measurements such as potentiodynamic polarization AC impedance techniques and Electrochemical Frequency Modulation.
The third chapter:
Deals with the results obtained and their discussion under four separated sections.
SectionA:
Potentiodynamic polarization measurements were carried out for Tin in 0.6 M NaCL in the absence and presence of different concentrations of the investigated compound The polarization curves indicated that these compounds influence both cathodic and anodic processes The order of decreasing inhibition efficiency for these additives is:
The effect of temperature on the corrosion rate of in 0.6M NaCL over two temperature degrees 25 and 40 Cin the absence and presence of 1x10-6 of the investigated compound has been studied The % inhibition efficiency is found to decrease with increasing the temperature this indicated that these activation energies were calculated from the Arrhenius equation
Also an estimate of heat of adsorption was obtained from the trend of surface voverage with temperature as follows
Section b:
AC impedance spectroscopy measurements were carried out for tin in 0.6 M NaCL in the absence and presence of different concentrations of the investigated compounds.
from the impedance data we conclude that:
-The value of Rct increases with increase in the corrosion inhibition efficiency in acidic solution
The value of double layer capacitance by increasing the inhibitor concentration This is due to the adsorption of these compounds on the electrode surface leading to a film formation on the Sn surface
-THE % IE obtained from EIS measurements are close to those deduced from polarization
Section C
Electerochemical Frequency Modulation measurements were carried out for Tin in aerated 0.6 MaCL solutions devoid of and containing different concentrations of prpanentrile compounds at 25C Each spectrum is a current response as a function of frequency .The two large peaks are the response to the 2 Hz and 5Hz excitation frequencies These peaks are used by the EFM 140 software package to calculate the corrosion current and Tafel constants.
Section D
The influence of the chemical structure of the usd compounds on their % inhibition efficiency was discussed The order of this % inhibition efficiency depends mainly upon the type and position of the substituents group quantum chemical calculations were used to predict the efficiency of the investigated compound as corrosion inhibitors It is clear that the inhibitition efficiency increases with the energy of the highest occupied molecular orbital .