Evidence is presented for the formation of free 1,8-dehydronaphthalene in oxidations of 1-aminonaphtho[1,8-de]-triazine. 1,2-Addition of 1,8-dehydronaphthalene to olefins is stereospecific, and the overall reactions, which are significantly different from those of benzyne, can be explained by a singlet diradical structure. Also, the observed addition reactions are in striking agreement with recent molecular orbital calculations for dehydroaromatic species. As expected, 1,2-and 2,3-dehydronaphthalene, generated similarly, closely resemble benzyne. Other attempted routes to 1,8-dehydronaphthalene are described.