1,4-Benzodioxin and its 2-phenyl derivative can be prepared by the dehyration of their respective 2-hydroxy compounds under suitable conditions. 2-Methyl-1,4-benzodioxin can be similarly prepared but is more readily obtained by the isomerization of 2-methylene-1,4-benzodioxan. The structures of these compounds have been authenticated by analysis, UV, PMR and IR spectroscopy and by hydrogenation experiments. 2-Hydroxy-1,4-benzodioxans are shown to exist as such rather than as their open-chain carbonyl tautomers. Previous descriptions of the preparation and structures of the above compounds are discussed.

中文翻译：

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1,4-苯并二恶英-I：1,4-苯并二恶英及其2-甲基和2-苯基衍生物的制备

1，4-苯并二恶英及其2-苯基衍生物可通过在适当条件下将其各自的2-羟基化合物脱水而制得。可以类似地制备2-甲基-1，4-苯并二恶英，但是更容易通过2-亚甲基-1，4-苯并二恶烷的异构化获得。这些化合物的结构已通过分析，UV，PMR和IR光谱以及氢化实验进行了鉴定。显示2-羟基-1,4-苯并二恶烷原样存在，而不是它们的开链羰基互变异构体。讨论了上述化合物的制备和结构的先前描述。