Fatty Acids in Heterocyclic Synthesis Part XII: Synthesis of Surfactants from Pyrazole, Isoxazole, Pyrimidine and Triazine, Incorporating the 1,3,4-Thiadiazole Moiety Having Dyeing and Antimicrobial Activities

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 regio-specificity for addition of different nucleophiles to these tautomers; thus, nitrogen nucleophiles such 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 the 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 at 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 mol 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 the manufacture of dyes, drugs, cosmetics, emulsifiers, pesticides, luminphores for optical applications and many other industries with low toxicity to human beings and the environment owing to their high solubility and good biodegradability.