Synthesis and reactions of some methylenebis-4H-1,2,4-triazol derivatives and investigation of their antimicrobial activities

Synthesis of 5,5?-methylenebis(4-phenyl-4H-1,2,4-triazol-3-thiol) (53) was preformed starting from malonohydrazide via the formation of 2,2?-(1,3-dioxopropan-1,3-diyl)bis(N-phenylhydrazincarbothioamide) (52). Treatment of compound 53 with ethyl bromoacetate and hydrazine hydrate, led to the formation of 2,2?-{methylenbis[(4-phenyl-4H-1,2,4-triazol-5,3-diyl)thio]}diacetohydrazide (55). Reaction of 55 with several aromatic aldehydes produced the corresponding arylmethyleneacetohydrazides (56a-d). The reaction of 53 with furan-2-ylmethanamine (for 57a) or morpholine (for 57b) resulted in the formation of the corresponding Mannich bases, 5,5?-methylenebis(2-[(alkylmethylamino)methyl]-4-phenyl-2,4-dihydro-3H-1,2,4-triazol-3-thion) compounds (57a, 57b). Treatment of 53 with 3,4-dichloronitrobenzene in basic media yielded 3,3?-methylenebis{5-[(2-chloro-4-nitrophenyl)thio]-4-phenyl-4H-1,2,4-triazol} (58). Nitro groups of compound 58 was reduced to amino group by the treatment of 58 with hydrazine hydrate in the presence of Pd-C catalist, thus, (4{[5-({5-[(4-amino-2-chlorophenyl)thio]-4-phenyl-4H-1,2,4-triazol-3-yl}methyl)-4-phenyl-4H-1,2,4-triazol-3-yl]thio}-3-chlorophenyl)amine (59). The structures of the newly synthesized compounds were confirmed by FT-IR, Mass, 1H NMR and 13C NMR spectroscopic methods. All compounds were screened for their antimicrobial activities.