2-amino-5-mercapto-1,3,4-thiadiazole [I] were prepared by the cyclization of thiosemecarbazide with carbon disulphide and anhydrous  sodium carbonate in ethanol as a solvent. The reaction of compound [I] with alkyl halides yielded 2- amino-5-thioalkyl-1,3,4- thiadiazole [II] and [III] . Compound [II] and [III] were reacted with different aromatic aldehydes to yieled 2-[(substituted benzyliden ) amino] -5- thioalkyl-1,3,4- thiadiazole [IV]a-c , [V]a-d and [VI]a-d .  Schiff ,s bases [IV]a-c , [V]a-d and [VI]a-d  were found to react with  2mercapto benzoic acid in the triethyl amine to give 3-[ 5-( alkylthio) -1,3,4- thiadiazol-2-yl] 2,3- dihydro- 2- (aryl) benzo [e] [1,3] thiazine -4-one [VII]a-

This work contain many steps starting from esterification of isophthalic acid to yield diester compound [I] which was converted to their acid hydrazide [II], then the later compound reacted with ethylacetoacetate to yield pyrazol-5-one compound [III]. Afterword added acetyl chloride to give the compound [IV], thereaction of this compound with theiosemicarbazide ledto produce a new carbothioamide compound [V], Which was reacted with ethyl chloro acetate to yield thethioxoimidazolidin compound [VI]. The condensation reaction of this compound with different substituted aldehyde give new alkene derivatives[VII]a-d. The synthesized compounds were characterized by melting points , FT-IR ,1H-NMR and Mass spectroscopy .

  In this study, Schiff's bases [S3,S4] were synthezied by condensation of N,N-dimethyl amino benzaldehyde with primary aromatic amine[N-(hydrazinyl methyl)benzamide]. These Sciff's bases were found to react with maleic anhydride and phthalic anhydride to give 1,3Oxazepine[S5,S6,S7,S8] in good yields.            The structures confired by m.p ,T.L.C.,FT.IR and 1H-NMR (of some of them).

In this paper the new starting material 2-(5-chloro-1H-benzo[d]imidazole-2-yl) aniline (1) was synthesized by the condensation reaction of 4-chloro-o-phenylenediamine and anthranilic acid .The new Mannich base derivatives were synthesized using formaldehyde and different secondary amines to synthesize a new set of benzimidazole derivatives(2-5). Also, the new Schiff-base derivatives (6-10) were synthesized from the reaction of compound (1) with various aromatic aldehydes and the closure-ring was done successfully using mercapto acetic acid to get the new thiazolidine derivatives(11-12).These new compounds were characterized using some physical techniques like:FT-IR Spectra and 1HNMR Spectra.

 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.

               The new symmetry pyromellitdiimide [VII]_a-c,n  were synthesized by two-step reactions from the corresponding pyromellitic dianhydride . A new symmetrical amic acid [VI]_a-c,n was synthesized by the reaction of pyromellitic dianhydride with different heterocyclic amines in dry acetone . The second reaction step includes  intramolecular cyclization of amic acid in the presence of  sodium acetate -acetic anhydride system at 85⁰C. Structures  of  the synthesized compounds have been ascertained by their melting points , C.H.N analysis , UV-Vis, FTIR and ¹HNMR spectroscopy.

In this research two series of the new derivatives of Trimethoprim and paracetamol drugs have been prepared which known as a high medicinal effectiveness. Series (A) is including the interaction of diazonium salt of trimethoprim and coupling with some substituted phenol compounds (2-amino phenol, 3-ethyl phenol, 1-naphthol, 2-nitro phenol, Salbutamol). Series (B) is including the interaction coupling alkali solution of paracetamol with diazonium salt of some substituted aniline compounds (Benzedine, 2, 3-di chloro aniline, Trimethoprim, Anilinium chloride, 2-nitro- 4-chloro aniline).Chemical structures of all synthesized compounds were confirmed by UV-visible and FTIR spectroscopy.

Inthis study new derivatives of Schiff bases and nucleoside analogues have been synthesized from the starting material D-glucose after a series of reactions. Derivative 1 was prepared from D-glucose then react with P-bromoacetophenone gave derivative 2 was reacted with dimethyl sulfoxide and acetic anhydride for dehydration a molecule of water gave 3. The spiro ring was prepared at 3-position from the reaction of 3 derivative with 1-phenyl-2–thioureagave 4. The protection group at 1 position was removed by using acetic acid fllowed by periodate oxidation to obtain 6. Reaction of 6 with hydrazide derivative at once and dtriazole derivative at another gave 8 and 9 respectively. Compound 6 was reduced to gave derivative 7. The 1-hydroxylgrou