Preparation of Aromatic Organic Compounds containing Hetero-atoms as Corrosion Inhibitors for Mild Steel in Acidic Solution

1-In this study, some organic compounds contain hetero-atoms were synthesized by several steps as following: First; 4-phenylazoaniline [1] and 4-phenyl azophenol [17] were prepared in two steps:•The treatment of a primary aromatic amine (aniline) with nitrous acid to form a diazonium salt.Coupling reaction of aromatic diazonium ion with activated aromatic ring (aniline, phenol).Second; Organic compounds (1E, 4E)-1, 5-diphenylpenta-1, 4-dien-3-one [2], (E)-3-(furan-2-yl) acrylaldehyde [3] were prepared by aldol condensation reaction between two molecules of an aldehyde or a ketone.Third; Organic compounds [4-11] were prepared by reaction of 4-phenylazoaniline [1] in one step by a condensation reaction between the carbonyl group of aldehydes or ketone and the amino group to yield the following compounds:[4]- N, N-dimethyl-4-[(E) - 4-{(E)-phenyldiazenyl} phenylimino] methyl aniline [5]- (E)-N-(4-bromobenzylidene)-4-[(E)- henyldiazenyl] aniline [6]- (E)-N-(4-nitrobenzylidene)-4-[(E)-phenyldiazenyl] aniline [7]- (Z)-N-(furan- -ylmethylene)-4-[(E)-phenyldiazenyl] aniline
[8]- N-[(1E, 4E)-1, 5-diphenylpenta-1, 4-dien-3-ylidene]-4-[(E)-phenyldiazenyl] aniline
[9]- (E)-N-[(E)-3-phenylallylidene]-4-[(E)-phenyldiazenyl] aniline [10]- (E)-5-[4-{(E)-phenyldiazenyl} phenylimino] pentane-1, 2, 3, 4-tetraol [11]- (E)-N-[(E)-3-{furan-2-yl} allylidene]-4-[(E)-phenyldiazenyl] aniline Organic compound (E)-4-(4-nitrobenzylideneimino) benzenthiol [12] was prepared in one step by a condensation reaction between carbonyl group of p-nitrobenzaldehyde and aromatic primary amino group of p-aminothiophenol.
Fourth; Organic compounds [13-16] were prepared by reaction of (E)-4-(4-nitrobenzylideneimino) benzenthiol [12] in one step by an alkylation reaction between (Ethyl Bromide, n-propyl Bromide, Benzyl Chloride or 1, 2-Dichloroethane) and thiol group to yield following compounds: [13]- (E)-4-(ethylthio)-N-(4-nitrobenzylidene) aniline
[14]- (E)-N-(4-nitrobenzylidene)-4-(propylthio) aniline [15]- (E)-4-(benzylthio)- -(4-nitrobenzylidene) aniline [16]- (E)-4-(2-chloroethylthio)-N-(4-nitrobenzylidene) aniline
Organic compounds [18-20] were prepared by reaction of (E)-4-(2-chloroethylthio)-N-(4-nitrobenzylidene) aniline [16] with ((E)-4-(4-nitrobenzylideneimino) benzenthiol [12], 4-phenyl azophenol [17] or p-aminopyridine) to yield the following compounds:
[18]- (NE, N’E)-4, 4’-[ethane-1, 2-diylbis (sulfanediyl)] bis [N-(4-nitrobenzylidene) aniline]
[19]- (E)-N-(4-nitrobenzylidene)-4-[2-{4- Z)-phenyldiazenyl} phenoxy] ethylthio aniline [20]- (E)-N-[2-{4-(4-nitrobenzylideneamino) phenylthio} ethyl] -4-amine pyridin 2-The prepared compounds were identified by melting points, FT-IR, UV-visb., 1H-NMR and 13C-NMR spectroscopic techniques. 3-The prepared compounds [4-16] and [18-20] were used as corrosion inhibitors for mild steel in 1M H2SO4 at 30 C. Weight loss measurement was regarded as evaluation method to test the inhibition efficiency of the above compounds.
4-Semi-empirical molecular quantum calculations within the PM3 method as implemented in Hyperchem package were used to study the relationship between molecular structure and inhibition efficiency. The compound [8] showed lowest energy gap that gives good inhibition efficiency. Synthesis of organic compound [1-20] showed in these schemes