交联菲罗啉负载铜催化剂用于合成三甲基苯醌

烷基取代的苯醌可用作多种生物活性化合物的功能结构单元。提出了一种在温和条件下,用氧气氧化2,3,6-三甲基苯酚（TMP）得到2,3,5-三甲基-1,4-苯醌（TMQ,维生素E前体）的方法。利用Friedel-Crafts烷基化反应,成功制备了一种基于1,10-菲罗啉的交联多孔聚合物负载铜催化剂Cu/PPhen。采用氮气吸附脱附、SEM、FTIR和XPS对催化剂Cu/PPhen-4进行了一系列的表征,获得了催化剂的基本结构特征。并考察了催化剂的加入量、溶剂、氧气压力、反应温度以及反应时间等因素对Cu/PPhen-4催化氧化制备2,3,5-三甲基-1,4-苯醌的影响,得到最佳的工艺条件。当2,3,6-三甲基苯酚的加入量为136 mg时,催化剂量为150 mg,乙腈量为2 ml,0.5 MPa的氧气,40℃下反应4 h,2,3,5-三甲基-1,4-苯醌的收率可以达到99%。催化剂Cu/PPhen-4具有较好的稳定性,可以回收至少五次,活性几乎没有下降。

Copper catalyst supported on cross-linked phenanthroline for oxidative synthesis of 2,3,5-trimethyl-1,4-benzoquinone

Alkyl-substituted benzoquinones were versatile building blocks for a variety of biologically active compounds. The catalytic oxidation of 2,3,6-trimethylphenol (TMP) to 2,3,5-trimethyl-1,4-benzoquinone (TMQ, vitamin E precursor) with oxygen gas was proposed under mild conditions. The cross-linked porous polymer (PPhen) was synthesized by Friedel-Crafts alkylation of 1,10-phenanthroline, and the related Cu catalysts (Cu/PPhen) were prepared. The prepared Cu/PPhen catalysts were characterized by nitrogen adsorption and desorption isotherms, scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) .The basic structure of the Cu/PPhen catalysts were obtained. Reaction conditions, such as catalyst loading, solvent, oxygen pressure, reaction temperature and reaction time were studied, and 2,3,5-trimethyl-1,4-benzoquinone was obtained in 99% yield with the optimized reaction conditions. The optimized reaction conditions were achieved as 136 mg 2,3,6-trimethylphenol with 150 mg the Cu/PPhen-4 catalyst in 2 ml acetonitrile, under 0.5 MPa O₂ at 40℃ for 4 h. The Cu/PPhen-4 catalyst has good stability and can be recovered at least five times with almost no decrease in activity.