1-[(5-Phenyl-1,3, 4-oxadiazol-2-yl)thio] acetone (POTA) was synthesized and tested as a new corrosion inhibitor for low carbon steel in 1 M hydrochloric acid. The diagnosis of POTA was carried out by FTIR and NMR analysis. Inhibitor performance was investigated using mass loss technique. POTA was acted as a moderate corrosion inhibitor for low carbon steel in 1 M hydrochloric acidic solution with efficiency more than 70%. The inhibitor performance was attributed to the formation of an adsorption layer on the low carbon steel surface. The mechanism of inhibitor adsorption on the low carbon steel surface was according to the Langmuir adsorption isotherm. The value of adsorption heat was within the range of chemical adsorption. Quantum chemical studies were adopted as a theoretical tool to clarify the mechanism of inhibition and to support the experimental part.

The aim of the study is to synthesise and. Characterize — some novel, "tetrazole., -5-thiol” derivatives. Firstly, the “1-phenyl-1H7-tetrazole-5-thiol” (A1) has been., synthesised by the reaction of phenylisothiocyanate with NaN3 in water as a solvent. Secondly, the tetrazole-5-thiol derivatives (A2-A4) were synthesised by the alkylation reaction of the compound (A1) with chloroacetone, phenacyl bromide and chloromethyl acetate respectively. The resulted percentage yield was relatively high (92%, %95, %90 respectively). Compound (A5) was synthesised by the reaction of ethyl acetate tetrazole derivative (A4) with hydrazine. Moreover, the derivatives (A6-A11) were synthesised by the reaction of the (A5) with various substituted aromatic aldehydes. Moreover, compounds (A12-A13) have been synthesised by the cyclization reaction of compound A5 with acetylacetone and phenyl acetylacetone respectively. The produced compounds have been identified by IR, 13C-NMR and 1H-NMR Spectroscopy, and the quantities of various of the physical data (melting point, the shape of crystal and color). Finally, the compounds were examined for their biological activities alongside two kinds of bacteria (E. Coli and Staphylococcus aureus). Compounds A2, A4, A8, A11 and A13 showed the highest inhibition activity against E. Coli. Compounds A2, A9, A10and A13 showed the maximum activity against Staphylococcus aureus.

A series of novel heterocyclic derivatives [A1-A7] have been synthesized by the alkylation reaction of the (SH, NH, OH) of various heterocyclic (oxadiazole, thiadiazole,4-hydroxy coumarin and benzothiazole) with chloro acetone or 2-bromoacetophenone. The resulting percentage yield of synthesized compound was relatively (69-85%). The producing compounds have been identified by infrared radiation (IR), proton nuclear magnetic resonance (1H-NMR), Carbon-13 nuclear magnetic resonance (13C-NMR) spectroscopy, and the quantities of various physical properties (melting point, crystal shape, and color). The synthesized derivatives were examined for their antioxidant activities.

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The present study introduces the synthesis of two series of tetrazole derivatives. Firstly, monosubstituted S1 was prepared by the reaction of ethyl 4-aminobenzoate with an amount of sodium azide and triethyl orthoformate in hot glacial acetic acid. Then, ethyl 4-(1H-tetrazol-1-yl) benzoate S1 was treated with a solution of hydrazine hydrate to prepare acetohydrazide S2. After that, tetrazole derivatives S3-S4 were prepared via the reaction of acetohydrazide S2 with various aromatic aldehydes. Secondly, compound 1,5-disubstituted tetrazole S5 was prepared from the reaction of aryl isothiocyanate with sodium azide in water presence. Then alkylation to compound S5 was made with ethyl chloroacetate to produce S6. In the next step, S6 was reacted with hydrazine hydrate to get acetohydrazide S7. Moreover, the produced S7 was reacted with some aromatic aldehydes for the synthesis of S8-S10. The structures of synthesized compounds were confirmed by the different available spectral methods, i.e., FTIR, 1H-NMR and 13C-NMR spectroscopy. The antioxidant activity of the synthesized compounds was evaluated by the use of 2,2-diphenyl-1-picrylhydrazyl. The results showed that compound S10 has the highest value as radical scavenging among the synthesized compounds.