This research included synthesizing a series of heterocyclic compounds where the compound 2chloroacetohydrazide was synthesized from ethyl chloroethanoate with Hydrazine hydrate 95%. The reaction was carried out in the cold condition. 2-(pyrimidin-2-ylamino)acetohydrazide was prepared by reaction A1 with 2-amino pyrimidine in absolute ethanol using Potassium hydroxide (KOH); then reaction 2-(pyrimidin-2-ylamino) acetohydrazide with different aldehydes to produce Schiff bases derivatives A3 -A14 which was introduced in two different synthetic methods the first was synthesized. Then tetrazole derivatives [A15-A19] were synthesized from the hydrozone reactor (Schiff bases) [A3-A14] prepared by reaction Schiff base with sodium azide. In a second way, derivatives 2, 3-dihydroquinozoline-4-one [A20-A24] were synthesized from the interaction of some of Schiff's bases in the third step with anthralenic acid (2-amino benzoic acid) using 1,4-dioxane as a solvent; the synthetic compounds were diagnosed with some spectral methods, such as UV, FTIR, 1H-NMR and quantitative analysis of the elements (C.H.N.S.). Some synthetic compounds on the growth of four types of bacterial isolates known to be resistant to antibiotics were studied. Amoxicillin and Ampicillin were used as control samples, and some of the prepared compounds showed good inhibiting efficacy against the used bacteria (Escherichia coli, Klebsiella pneumonia, Staphylococcus aureus, and Staphylococcus epidermidis)

In this paper, we consider the Synthesis of a series of various 4-amino antipyrine derivatives containing 1,3-thiazinan-4-one, 1,3-oxazinan-6-one, and 1,3-oxazepin-4,7-dione in its structure. These derivatives were obtained via cycloaddition of the methenamine group in Schiff base analog of 4-amino antipyrine with 3-mercaptopropanoic acid, 3-chloropropanoic acid, maleic and citraconic anhydride, respectively. The Schiff bases were prepared in excellent yields by condensation of 4-amino antipyrine with 3-nitro- or 3-bromobenzaldehyde in n-butanol. We characterize the desired products by C.H.N.S analysis, FT-IR, and 1HNMR spectroscopy.

A new series of Sulfamethoxazole derivatives was prepared and examined for antifibrinolytic and antimicrobial activities. Sulfamethoxazole derivatives bear heterocyclic moieties such as 1,3,4-thiadiazine {3},  pyrazolidine-3,5-diol {4} 6-hydroxy-1,3,4-thiadiazinane-2-thione {5} and [(3-methyl-5-oxo-4,5-dihydro-1H-pyrazol-4-yl)diazenyl] {8}. Their structures were elucidated by spectral methods (FT-IR, H1-NMR). Physical properties are also determined for all compound derivatives.  Recently prepared compounds were tested for their antimicrobial activity in the laboratory. Each screened compound showed good tendency to moderate antimicrobial activity.

In this research various of 2,5-disubstituted 1,3,4-oxadiazole (Schiff base, oxo-thiazolidine , and other compounds) were synthesized from 2,5-di(4,4?- amino-1,3,4-oxadiazole ) which use quently synthesized from mixture of 4-amino benzoic acid and hydrazine in the presence of polyphosphorus acid. The synthesized compounds were characterized by using some Spectral data (UV, FT-IR, and 1H-NMR).

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