1- This work involves preparation of some organic compounds contain hetero-atoms, that starting from (E)-2-benzylidene hydrazine carbothioamide [1] to (E)-5-(2-chloro ethyl thio)-N-(1-phenyl ethylidene)-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 of Thiosemicarbazide derivatives to produce the compounds:
[1]- (E)-2-benzylidene hydrazine carbothioamide.
[2]- (E)-2-(4-nitro benzylidene) hydrazine carbothioamide.
[3]- (E)-2-(4-(dimethyl amino) benzylidene) hydrazine carbothioamide.
[4]- (E)-2-(3-nitro benzylidene) hydrazine carbothioamide.
[5]-(z)-2-(1-phenyl ethylidene) hydrazine carbothioamide.
- 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 ketone and 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-(benzyl thio)-1,3,4-thiadiazol-2-amine.
[13]-(E)-5- (benzylthio)-N-(4-nitro benzylidene)-1,3,4-thiadiazol-2-amine.
[14]-(E)-5-(benzylthio)-N-(4-(dimethyl amino) benzylidene)-1,3,4-thiadiazol-2-amine.
[15]-(E)-5- (benzylthio)-N-(3-nitro benzylidene)-1,3,4-thiadiazol-2-amine.
[16]-(E)-5-(benzylthio)-N-(1-phenyl ethylidene)-1,3,4-thiadiazol-2-amine.
[17]-(E)-N-benzylidene-5-(2-chloro ethylthio)-1,3,4-thiadiazol-2-amine.
[18]-(E)-5-(2-chloro ethylthio)-N-(4-nitro benzylidene)-1,3,4-thiadiazol-2-amine.
[19]-(E)-5-(2-chloro ethylthio)-N-(4-(dimethyl amino) benzylidene)-1,3,4-thiadiazol-2-amine.
[20]- (E)-5-(2-chloro ethylthio)-N-(3-nitro benzylidene)-1,3,4-thiadiazol-2-amine.
[21]-(E)-5-(2-chloro ethylthio)-N-(1-phenyl ethylidene)-1,3,4-thiadiazol-2-amine.
2- The prepared compounds were identified by melting points, F.T.I.R, UV-visible and 1H-NMR spectroscopy and the result obtained are compatible the structures assigned to these compounds.
3- The above organic compounds which contain hetero-atoms were used as corrosion inhibitors for mild steel in 1M H2SO4 at 30oC. Weight loss regards as evaluation method 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.
The preparation steps of the compounds [1-21] can be represented as shown in the following scheme:
