Synthesis and Mass Spectral Fragmentation Patterns of some 2-Thiohydantoin, Salicyladazine and Pyradazine Derivatives

Abstract

3-[(5-Arylazo-2-hydroxybenzylidene)amino]-2-thiohydantoins 3a-c were prepared via condensation of 5-arylazo-2-hydroxybenzaldehyde 1 with thiosemicarbazide, followed by cyclization of 2 with ethyl chloroacetate. Acetylation of 3 with acetic anhydride yielded the corresponding diacetyl derivatives 6a-c.
Hydrazinolysis of compounds 3 and 6 with hydrazine hydrate
gave the corresponding 5-arylazosalicylaldehydes 5a-c.
Ammonolysis of benzoin (7) with ammonia afforded the
corresponding 2,3,5,6-tetraphenyl-1,4-dihydropyradazine (8). Acetylation of compound 8 with acetic anhydride gave the corresponding 1,4-diacetylpyradazine 9. The electron impact ionization mass spectra of the compounds pairs 3a and 6a, 3b and 6b, and 3c and 6c show a base peak of m/z 77, m/z 91 and m/z 111 resulting from fragmentation. The base peak of compounds 5a, 5b and 5c is the molecular ion for all these compounds.