الفهرس 
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Abstract
The objective of the present work is to plan and investigate access to the synthesis of new biphenyl isosteres and phenylfurylidene derivatives. Also, this work is affirmed to evaluate the synthesized compounds for their insecticidal and anti-corrosion activities. Furthermore, computational studies were conducted in order to compare experimental and theoretical data as these approaches offer good explanations for accurate predictions before the actual experiments were performed. Therefore, the introduction in thesis includes schemes 1-81 and the sequences for the synthesis of the target compounds in this thesis are depicted in schemes 82-86. The work in this thesis is divided into two main parts: Part I: Synthesis of inventive biphenyl and azabiphenyl derivatives as potential insecticidal agents against the cotton leafworm, Spodoptera littoralis 1. Monocationic Biphenyl and Aza-biphenyl derivatives: 4a-h & 8a-d: The preparation of the new biphenylcarboxamidines 4a-h begin with Suzuki coupling reaction of bromobenzonitriles 1a, b with the appropriate phenylboronic acids 2a-d to furnish biphenylcarbonitriles 3a-h, which is converted to biphenylcarboxamidines 4a-h by the action of lithium trimethylsilylamide, hydrogen chloride, and NaOH (Scheme 82). Biphenyl amidine 4a-h was synthesized from biphenyl carbonitrile 3a-h according to (Scheme 83). On the other hand, treatment of bromopicolinonitrile 5 with substituted boronic acid derivatives 6a-d yielded the corresponding phenylpicolinonitrile derivatives 7a-d. Then, transformation of phenylpicolinonitriles 7a-d to phenylpicolinimidamide derivatives 8a-d via the same steps mentioned above for synthesis of biphenyl amidine (Scheme 84). 1.1. Reterosynthetic Analyses of Biphenylcarboxamidines 4a-h Disconnection starts with function group interconversion (FGI) of the amidine group to its corresponding carbonitrile group. The disconnection of biphenylcarbonitriles 3a-h may be done via three routes: Suzuki, Stille and Ullmann. 1.2. Insecticidal activity Biphenylcarboxamidines and phenylpicolinimidamide derivatives were evaluated in vivo insecticidal activities against the cotton leafworm, Spodoptera littoralis. As regards the indomitable LC50 and LC90 values, biphenyl and aza-analogues 8d, 8a, 4b, and 8b, revealed the furthermost forceful toxic effects with LC50 values of 113.860, 146.265, 216.624, and 289.879 ppm, respectively, and toxicity index of 100%, 77.85%, 52.57%, and 39.28%, respectively. 1.3. Computational studies Computational calculations were performed to determine the chemical reactivity and biological evaluation of synthesized compounds. The DFT approach B3LYP and 6-311G basis set were used to investigate the optimized structures of the synthesized compounds. Results showed that compound 3b was the most effective and reactive molecule in the carbonitrile moieties, with a lower band gap (-4.513 ev). Geometrical studies revealed that 4’-fluoro-[1,1’-biphenyl]-4-carboxamidine 4b was the most active molecule compared to other amidine derivatives. Part II. Furylidene/biphenylidene-pyrimidine derivatives 2.1. Trimethoxyphenylfurylidene/pyrimidine derivatives Suzuki coupling reaction of 5-bromo-1,2,3-trimethoxybenzene (9) with (5-formylfuran-2-yl)boronic acid (10) yielded furylcarbaldehyde 11. Then, furylcarbaldehyde 11 was condensed with barbituric acid derivatives 12a-d to produce the target furylidene derivatives 13a-d (Scheme 85). 2.2. Novel Biphenylidene-Thiopyrimidine Derivatives as Corrosion Inhibitors for Carbon-Steel in Oilfield Produced Water Suzuki coupling reaction of 4-bromo-N,N-dimethylaniline (14) with (4-formylphenyl)boronic acid (15) furnished the biphenylcarbaldehyde 16. Then, biphenylcarbaldehyde 16 was condensed with thiobarbituric acid derivatives 17a-c to afford the target biphenylidene-thiopyrimidine derivatives 18a-c (Scheme 86). 2.2.1. Potentiodynamic polarization measurements Potentiodynamic polarization measurement were carried out for carbon-steel in oilfield produced water in the absence and presence of different concentration of biphenylidene-thiopyrimidine derivatives. The polarization curves indicated that these inhibitors are mixed types of inhibitors. 2.2.2. EIS studies Electrochemical impedance spectroscopy (EIS) was carried out for carbon-steel in oilfield produced water in the absence and presence of different concentration of biphenylidene-thiopyrimidine derivatives. 2.2.3. Adsorption isotherm Adsorption isotherm gave good insight on the anticorrosion performance between carbon steel and the investigated organic compounds. Adsorption behavior of inhibitors described by Langmuir adsorption isotherm. 2.2.4. Quantum chemical calculations DFT calculations were used to explore the chemical and physical properties of biphenylidene-thiopyrimidine derivatives. Exploring the values of EHOMO, ELUMO and ΔE for the studied compounds, the order of inhibition can be anticipated as follows: 17a>17b>17c. 2.2.5. Molecular Simulations The interaction of biphenylidene- thiopyrimidine derivatives in aqueous media was explored by Monte Carlo simulation which was a powerful tool to provide the equilibrium position of inhibitors on Fe surface. The increasing order of adsorption energy of compounds was found in agreement with experimental method can be anticipated as follows: 17a>17b>17c. 2.2.6. Surface analysis (AFM) Atomic Force Microscopy (AFM) were carried out for carbon-steel in oilfield-produced water in the absence and presence of different concentrations of biphenylidene-thiopyrimidine derivatives. 2.2.7. Mechanism of Corrosion inhibition This part includes the inhibition mechanism of biphenylidene-thiopyrimidine derivatives. the influence of the structure of the investigated biphenylidene-thiopyrimidine derivatives on their inhibition efficiencies was discussed and the order of inhibition can be anticipated as follows: 17a>17b>17c.