The titled compounds were prepared from 2-amino-5-heptadecyl[1,3,4]thiadiazole (1). Diazotization of (1) produced (2) which was coupled with active methylene compounds and gave azo hydrazono derivatives (3A, 3B)a-d. It was found that there is ragio specificity for addition of different nucleophiles to these tautomers thus, nitrogen nucleophiles as hydrazine hydrate, hydroxylamine hydrochloride and thiourea were reacted via Azo tautomer (3A) to yield pyrazole, isoxazole and pyrimidine respectively (5-7) ,while carbon nucleophiles as phenylisocyanate was reacted via hydrazono tautomer (3B) and produced triazine derivatives (4). Additionally, the diazonium chloride (2) was coupled with alkaline 2-naphthol and produced 2-(5-heptadecyl-[1,3,4]thiadiazol-2-yl)-1,2-dihydro-3-oxa-1,2-diaza-cyclopenta[a]naphthalene (8).UV-visible spectra of the synthesized colored compounds (2-8) showed λ max (374-398)nm, while screening these compounds in vitro against micro-organisms (including structure-activity relationship (SAR) study) revealed high antibacterial and moderate antifungal activities. Propoxylation of compounds 1,3,5,6,7 and 8 with 3,5,7 moles of propylene oxide produced nonionic surfactants I(a-c)-IX(a-c) having surface active properties so, it is clear that the tested surfactants can be used in manufacture of dyes, drugs, cosmetics, emulsifiers, pesticides, luminphores for optical applications and many other industries with low toxicity to human being and environment owing to their high solubility and good biodegradability.