碘化钾在1,2-双(二溴甲基)苯及4位取代衍生物与反丁烯二腈反应中的作用

Function of Potassium Iodide in the Reaction of 1,2-Bis-(dibromomethyl)benzene and Its 4-Substituted Derivatives with Fumaronitrile

1,2-双(二溴甲基)苯及4位取代衍生物与反丁烯二腈在N,N-二甲基甲酰胺中反应12 h没有新的产物生成,在同样的条件下,加入碘化钾可使反应发生,主产物是2,3-二氰基萘及其6位取代衍生物,它的产率随加入的碘化钾的量不同而不同.当碘化钾的加入量相当于1,2-双(二溴甲基)苯及4位取代衍生物分子中溴的摩尔数,则1,2-双(二溴甲基)苯及其4位取代衍生物与反丁烯二腈基本作用完毕,反应产物主要是2,3-二氰基萘及其6位取代衍生物,产率87.1%.这个实验事实表明,碘化钾的作用机制不是传统意义上的催化剂而是一个反应试剂.据此,提出了上述反应的机理.

1,2-Bis（dibromomethyl）benzene and its 4-substituted derivatives would not react with fumaronitrile in N,N-dimethylformamide in the absence of potassium iodide. However, the same reaction happened in the presence of potassium iodide. The major product was 2,3-dicyanonaphthalene or its corresponding substituted derivatives. The yields depended on the adding amounts of the potassium iodide. When the adding amount of potassium iodide was equal to the molar amount of bromine atoms in 1,2-bis（dibromomethyl）benzene or its 4-substituted derivatives, the reaction was substantially completed and the main product was 2,3-dicyanonaphthalene or its corresponding substituted derivatives with yield of 87.1%. Based on this fact, the function of potassium iodide was not a catalyst but a reaction reagent, and the reaction mechanism was proposed.