1,2-(Ethylenedioxy)benzene 1,4-Benzodioxan 1,4-Benzodioxane 1,4-Benzodioxin, 2,3-dihydro- 493-09-4 Benzene, 1,2-[1,2-ethanediylbis(oxy)]- Ethylene o-phenylene dioxide NSC406705 Pyrocatechol ethylene ether