Preparation of some Organic Compounds containHetero- atoms as Corrosion Inhibiters forMild Steel in Acidic Media.

1- This work involves preparation of some organic compounds contain hetero-atoms, that starting from (E)-2-benzylidenehydrazinecarbothioamide[1]to (E)-5-(2-chloroethylthio)-N-(1-phenylethylidene)-1,3,4-thiadiazol-2-amine [21],are summarized below: - First set of organic compounds was prepared in one step by a condensation reaction between the carbonyl group of aldehydes or ketones and the amino group ofThiosemicarbazide derivatives to produce the compounds: [1]- (E)-2-benzylidenehydrazinecarbothioamide.
[2]- (E)-2-(4-nitrobenzylidene)hydrazinecarbothioamide. [3]- (E)-2-(4-(dimethylamino)benzylidene)hydrazinecarbothioamide. [4]- (E)-2-(3-nitrobenzylidene)hydrazinecarbothioamide. [5]-(z)-2-(1-phenylethylidene) hydrazinecarbothioamide.
- Second set of organic compounds was prepared by reaction of 5-amino-2-thiol-1,3,4-thadiazole in two steps: i) a condensation reaction between the carbonyl group of aldehydes or ketoneand the amino group; ii) an alkylation reaction between (benzyl chloride or 1,2-dichloro ethane) and thiol group to yield the following compounds: [12]-(E)-N-benzylidene-5-(benzylthio)-1,3,4-thiadiazol-2-amine. [13]-(E)-5-(benzylthio)-N-(4-nitrobenzylidene)-1,3,4-thiadiazol-2-amine. [14]-(E)-5-(benzylthio)-N-(4-(dimethylamino)benzylidene)-1,3,4-thiadiazol-2-amine.
[15]-(E)-5-(benzylthio)-N-(3-nitrobenzylidene)-1,3,4-thiadiazol-2-amine. [16]-(E)-5-(benzylthio)-N-(1-phenylethylidene)-1,3,4-thiadiazol-2-amine. [17]-(E)-N-benzylidene-5-(2-chloroethylthio)-1,3,4-thiadiazol-2-amine. [18]-(E)-5-(2-chloroethylthio)-N-(4-nitrobenzylidene)-1,3,4-thiadiazol-2-amine. [19]-(E)-5-(2-chloroethylthio)-N-(4-(dimethylamino)benzylidene)-1,3,4-thiadiazol-2-amine. [20]-(E)-5-(2-chloroethylthio)-N-(3-nitrobenzylidene)-1,3,4-thiadiazol-2-amine. [21]-(E)-5-(2-chloroethylthio)-N-(1-phenylethylidene)-1,3,4-thiadiazol-2-amine. 2-The prepared compoundswere identified by melting points, F.T.I.R, UV-visible and1H-NMR spectroscopy and the result obtained are compatible the structures assigned to these compounds. 3- The above organic compounds which contain hetero-atomswere used as corrosion inhibitors for mild steel in 1M H2SO4 at 30oC. Weight loss regards as evaluationmethod to test the inhibition efficiency of the above compounds.Tables (3-5) and (3-6) indicates that the protection efficiency E (%) increases with increasing the concentration of suggested inhibitors with the maximum inhibition efficiencies were achieved at 10-3 M. 4-Theoretical calculations to investigate the relationship between molecular structure and inhibition efficiency by using semi-empirical molecular quantum calculations within the PM3 method as implemented in HyperChem package.