萘的选择性羰基化

【作者】 王爽；

【导师】 胡望明；

【作者基本信息】 浙江大学 ， 化学工程， 2008， 硕士

【摘要】 2,6-萘二甲酸是制备新型聚酯PEN的主要原料。以萘为起始原料，经2-位选择性羰化、6-位的定位羰化和有限氧化的步骤合成2,6-萘二甲酸是一条有竞争力的工艺路线。本文对萘的选择性羰基化进行研究，考察[bmim]Br／AlCl₃离子液体以及[bmim]Br／AlCl₃离子液体-分子筛复合体系在Friedel-Crafts反应中的催化性能。合成了[bmim]Br离子液体，考察了反应温度对离子液体产率的影响。[bmim]Br离子液体在100～110℃下反应产率达到96％以上。测定了CO在[bmim]Br／AlCl₃离子液体中的平衡溶解度，考察了温度、压力、离子液体配比对CO平衡溶解度的影响。CO在[bmim]Br／AlCl₃离子液体中溶解性能优于[bmim]BF₄等离子液体。CO在[bmim]Br／AlCl₃离子液体中的平衡溶解度随着AlCl₃含量的升高而增大，随着温度的升高而减小，随着压力的升高而增大。研究了萘在离子液体中的Friedel-Crafts选择性羰化反应。[bmim]Br／AlCl₃催化体系中，萘能有效转化为α-萘甲醛。在反应最优条件（CO压力为1．5MPa，室温，[bmim]Br／AlCl）₃（1：2）为催化剂)下反应2h后，萘的转化率达到40％，且得到单一产物α位萘甲醛，选择性达到100％。在[bmim]Br/AlCl₃（1：2）-ZSM分子筛复合体系中，萘的羰基产物出现β位萘甲醛。在CO压力为1．5MPa，室温下反应2h后，产物中β位萘甲醛选择性达到50％以上。用HyperChem软件对反应中间体进行模拟分析，结合实验结果得到以下结论：[bmim]Br／AlCl₃离子液体的活性基团为Al₂Cl₆，其不仅具备活化羰基化试剂（CO）的作用，还能活化芳环，提高了萘的转化率。离子液体比传统无水三氯化铝催化性能更好且绿色环保，是Friedel-Crafts反应的优良催化剂，但其不具有β位选择催化性能。脱铝ZSM型分子筛分散在[bmim]Br／AlCl₃离子液体中形成的复合催化体系具有β位选择性，选择性达到50％以上。更多还原

【Abstract】 2, 6-naphthalenedicarboxylic acid is the main raw material to produce the novel polyester PEN. It is a advanced route to synthesize 2, 6-naphthalenedicarboxylic acid from naphthalene in 3 steps: 2-position selected acylation, 6-position oriented acylation and controlled oxidation. The selective Friedel-Crafts acylations of naphthalene in ionic liquid [bmim]Br/AlCl3 and the [bmim]Br/AlCl3-zeolite composite system were investigated.Firstly, ionic liquids （[bmim]Br） were synthesized and the influence of the reaction temperature on the reaction yield was studied. Secondly, the influence of temperature, pressure and ionic liquid composition on the solubility of carbon monoxide in ionic liquids （[bmim]Br/AlCl₃） were investigated. Finally, the Friedel-Crafts acylations of naphthalene in ionic liquid [bmim]Br/AlCl₃ and the [bmim]Br/AlCl₃-zeolite composite system were proceeded at room temperature under CO pressure of 1.5 MPa.The optimal yield over 96% can be achieved in the synthesis of [bmim]Br at 100-110℃. Carbon monoxide has higher solubility in ionic liquid [bmim]Br/AlCl₃ than in [bmim]BF₄. Its solubility increased as the fraction of AlCl₃ and the pressure increased, but decreased as the temperature increased. In the presence of ionic liquid [bmim]Br/AlCl₃, naphthalene can convert into 100%α-naphthaldehyde with a conversion over 40% under the optimum condition （CO pressure was 1.5 MPa, room temperature, [bmim]Br/AlCl₃（1:2） was used as catalyst, 2 hours）. When the reaction was carried out in the composite system of [bmim]Br/AlCl₃（1:2） and ZSM zeolite, also under CO pressure of 1.5 MPa and at room temperature,β-naphthaldehyde can be obtained with a selectivity over 50%.Combined the expeimental results with the simulation using HyperChem, we can draw the following conclusions: Al₂Cl₆ is the active group in [bmim]Br/AlCl₃, which can activate not only the acylation agent （CO） but the aromatic ring （naphthalene） as well. As a result, the conversion of naphthalene can be greatly increased. Apart from the high activity, Ionic liquid is a green Friedel-Crafts catalyst compared with the traditional anhydr-AlCl₃. Ionic liquid catalyst leads to 100%α-naphthaldehyde, but when it is mixed with ZSM zeolite,halfα-naphthaldehyde and halfβ-naphthaldehyde can be obtained.更多还原