The acetohydrazide derivative reacted with carbon electrophiles such as acid chlorides, acetylacetone, ethyl acetoacetate and aromatic aldehydes to give some interesting heterocyclic compounds. The hydrazide derivative reacted with acetophenone which in turn underwent Vielsmeier-Haack reaction. Also, the phthalazinethione has been synthesized and its behavior towards hydrazine hydrate, oxidizing agent and ethyl chloroacetate has been investigated. The newly synthesized compounds were characterized by spectroscopic data. The antimicrobial, the cytotoxic, and the antioxidant activities of some of the synthesized products were evaluated. Some of the tested compounds showed very strong cytotoxic activity with respect to the standard.