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The prepared aldazines (aldehyde azines) and ketazines (ketone azines) were allowed to react with 2 mol of the acetylene derivative. The first products formed were pentalene azine derivatives, which in some cases underwent skeletal rearrangment into acyclic tetraene azines. The latter underwent, in the case of some aldazine products, further skeletal rearrangment into N-allyl pyrazoles. The occurence of these rearrangments is dependant on the nature of the aldehydes or ketones used.Key words: dimethyl acetylenedicarboxylate (DMAD), aldazines, ketazines, N-allyl pyrazoles.

4‐Cyano‐5,6‐dimethylpyridazin‐3‐(2H)‐thione 3b was used as a key intermediate for the synthesis of novel polysubstituted thieno[2,3‐c]pyridazines.

Mureish (2014) Influence of phase stabilization and perovskite vanadate oxygen vacancies of the BINIVOX catalyst on photocatalytic degradation of azo dye under visible light irradiation, A layered Aurivillius-perovskite-type BINIVOX system with the general formula Bi 2 Ni (II)x V 1−x O 5.5−(3x/2) was developed as a novel photocatalyst for degradation of organic dyes. A series of the BINIVOX.x catalysts in the compositional range 0 ≤ x ≤ 0.20 were successfully synthesized by the standard solidstate reaction and characterized using X-ray powder diffraction, differential thermal analysis, UV-vis diffuse reflectance spectroscopy and Brunauer-Emmett-Teller BET surface area. Then, the photocatalytic activities of prepared catalysts were investigated for the first time through the degradation of a new azo dye named sodium 4-[(E)-(4,5-dimethyl-1H-pyrazolo [3,4-c] pyridazin-3-yl) diazenyl] naphthalen-1-olate and denoted as 4-SPPN in aqueous solution under visible light irradiation. Adsorption efficiency and photocatalytic activity of BINIVOX.x catalysts were correlated well with the variation in phase crystal structures stabilized at room temperature as a function of composition. The stabilized γ -BINIVOX phases in the tetragonal crystal system with space group I4/m mm exhibited the best photocatalytic performance which can be attributed to their higher specific surface area, narrower band-gap energy and higher oxygenvacancy concentration in the perovskite vanadate layers. In addition, the possible photocatalytic degradation mechanism of aqueous 4-SPPN dye was proposed under visible light irradiation.

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