Synthesis and Crystallography of 8-Halonaphthalene-1-Carbonitriles and Naphthalene-1,8-Dicarbonitrile

A convenient and high-yielding three-step synthesis of 8-halonaphthalene-1-carbonitriles has been achieved by ring opening of 1H-naphtho[1,8-de][1,2,3]triazine with the corresponding halides as the key step. Naphthalene-1,8dicarbonitrile also has been synthesised from 8-bromonaphthalene-1-carbonitrile via palladium-catalysed cyanation of the aryl bromide. The crystal structures of 8-chloronaphthalene-1-carbonitrile, the A polymorph of the bromo analogue, and naphthalene-1,8-dicarbonitrile are isomorphous with orthorhombic symmetry. The B polymorph of the bromo compound and the iodo analogue are also isomorphous, but with monoclinic symmetry. In all of the halo carbonitriles, the molecules are disordered with respect to the location of the halogen atoms and the nitrile groups. There are no intermolecular X???NC interactions in any of the solids.