Functionalization of Methylaromatic Hydrocarbons

摘要研究了1,4-、1,8-、2,3-和2,6-二甲基萘、4,4′-二甲基联苯和对二甲苯等二甲基芳烃的功能化反应，以实现1)二（溴乙基）芳烃、2)二（羟甲基）芳烃和3)芳二醛的高选择性和便捷性合成。在二甲基芳烃合成双（溴乙基）芳烃过程中，以n -溴丁二酰亚胺为溴化剂，在苯中可见光照射可显著提高双（溴乙基）芳烃的选择性和产物纯化效率。在相转移催化剂如三乙基苄基溴化铵的存在下，将双（溴乙基）芳烃在强碱水中回流，得到了高收率的双（溴乙基）芳烃，预计其与双（溴乙基）芳烃的化学亲和力很高。用四丁基高碘酸铵在二氧六烷中氧化双（溴乙基）芳烃，产率较高。为了获得高选择性的二醛，需要加入2.2 mol当量的四丁基高碘酸铵和类似蒽的溴捕集剂。由于二甲基芳烃不能直接氧化合成双（羟甲基）芳烃和芳二醛，因此上述合成方法具有重要意义。

Functionalization of dimethylaromatic hydrocarbons such as 1,4-, 1,8-, 2,3- and 2,6-dimethylnaphtalenes, 4,4' -dimethylbiphenyl and p-xylene was investigated in order to aim at highly selective and convenient syntheses of1) bis(bromomethyl)aromatics, 2) bis(hydroxymethyl)aromatics and 3) aromatic dialdehydes.In the synthesis of bis(bromomethyl)aromatics from dimethylaromatic hydrocarbons, visible light irradiation in benzene with N-bromosuccinimide as brominating agent was greatly effective in increasing selectivities of the bis(bromomethyl)aromatics and efficiency of product purification.Bis(hydroxymethyl)aromatics were produced in good yields by refluxing the bis(bromomethyl)aromatics in strongly basic water in the presence of a phase transfer catalyst like triethylbenzylammonium bromide, whose chemical affinity with the bis(bromomethyl)aromatics could be expected to be high.Aromatic dialdehydes were produced in good yields in the tetrabutylammonium periodate oxidation of the bis(bromomethyl)aromatics in dioxane. In order to achieve high selectivities of the dialdehydes, it was necessary to add 2.2 mol equivalents of tetrabutylammonium periodate and a bromine trap like anthracene.The synthetic methods described above are of significance since bis(hydroxymethyl)aromatics and aromatic dialdehydes cannot be synthesized by direct oxidation of dimethylaromatic hydrocarbons.