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碳酸二甲酯(DMC)高效催化合成 1,6-六亚甲基二氨基甲酸甲酯(HDC)研究
Thesis Advisor李会泉 ; 曹妍
Degree Grantor中国科学院研究生院
Place of Conferral北京
Degree Discipline化学工程
Keyword碳酸二甲酯(dmc) 1 Mn(Oac)2 6-六亚甲基二氨基甲酸甲酯(hdc) 催化机理 动力学

非光气清洁合成异氰酸酯是绿色化学化工研究热点。非光气热解法合成脂肪族异氰酸酯1,6-六亚甲基二异氰酸酯(HDI)过程中,其关键中间体1,6-六亚甲基二氨基甲酸甲酯(HDC)合成工艺存在反应效率低、反应机理不明确等问题。本文针对1,6-己二胺(HDA)和碳酸二甲酯(DMC)甲氧羰基化反应制备HDC工艺,围绕催化剂筛选、工艺条件优化、催化反应机理及催化反应动力学展开了系统研究,为非光气法高效制备HDI提供了基础支撑。主要研究内容和结论如下:(1)开展了HDA与DMC甲氧羰基化反应网络研究。采用GC-MS、FTIR、元素分析等手段确定出反应体系中的副产物主要包括中间产物1-(6-氨基)-六亚甲基单氨基甲酸甲酯(HMC)及其他7种甲基化副产物;进一步采用重结晶和柱层析结合的方法分离得到中间产物HMC,并建立了其相应气相标准曲线;最后,根据反应体系中存在的副产物推测了反应路径,建立了反应网络。(2)开展HDA与DMC甲氧羰基化反应均相/非均相催化剂筛选研究,结果表明均相催化剂Mn(OAc)2在该反应体系中具有较好的催化效果;在最优工艺条件下:反应温度为363K,DMC与HDA的摩尔比值为4:1,催化剂浓度为HDA质量的7%,反应时间为5h,HDA转化率达到100%,HDC收率达到98.0%。(3)利用在线红外光谱实验与密度泛函理论(DFT)模拟计算手段相结合研究了Mn(OAc)2均相催化机理,提出了Mn(OAc)2催化HDA和DMC甲氧羰基化反应制备HDC的两步反应机理:Mn(OAc)2先攻击HDA中的氨基N原子生成活性中间体,该活性中间体作为亲核试剂进一步攻击DMC羰基C原子生成氨基甲酸酯。(4)开展Mn(OAc)2均相催化HDA与DMC甲氧羰基化反应的动力学研究,发现较高的反应温度有利于HMC向HDC的转化;同时建立了动力学方程,计算得到HDC合成过程中两步反应的活化能分别为Ea1=47.0514kJ·mol-1和Ea2=60.4504 kJ·mol-1,指前因子分别为A1=1.4645×102 (mol/L)-3.5432?min-1和A2=3.6519×104 (mol/L)-3.3226?min-1。

Other Abstract

The non-phosgene synthesis of isocyanate is a hot spot in the green chemical research. 1,6-Hexane diisocyanate (HDI) is an important aliphatic isocyanate, and dimethylhexane-1,6-dicarbamate (HDC) is the key intermediate of HDI synthesis by decomposition method. Now, synthesis of HDC from 1,6-hexanediamine (HDA) and dimethyl carbonate (DMC) attracts increasing attention from the chemists. However, the process has the disadvantages of low reaction efficiency and ambiguous reaction mechanism. In order to solve these problems, synthesis of HDC under a moderate temperature and atmospheric pressure with catalyst is studied in this thesis. A high efficient catalyst is screened. Based on the screened catalyst, the conditions optimization, catalytic mechanism and reaction kinetics are studied systematically. The main conclusions are exhibited as follows:(1) The reaction network of methoxycarbonylation of HDA with DMC is investigated. The main and by-products of the reaction are identified by GC-MS, FT-IR and elemental analysis. It is found that there are 7 kinds of by-products in this system except the intermediate, methyl-6-aminohexane-1-carbamate (HMC). HMC is separated through the combination of recrystallization and column chromatography. And the standard curves of HDA, DMC, HMC and HDC are established. The possible main and side reactions of the whole process are analyzed and the possible reaction network is put forward. (2) The highly efficient catalyst for the reaction between HDA and DMC is studied. Homogeneous and heterogeneous catalysts are screened in this thesis. Mn(OAc)2 is found as a new effective catalyst for this reaction among the evaluated homogeneous catalysts. Under the optimum conditions of 7wt% catalyst concentration, 4:1 DMC-to-HDA molar ratio, 363 K reaction temperature and 5 h reaction time, the HDC yield can reach as high as 98.0% with HDA totally converted. (3) The interactions between Mn(OAc)2 and substrates are investigated by Online Fourier Transform Infrared (FTIR) and Density Functional Theory (DFT) calculations. The whole process can be proposed that, first the reactive intermediate is formed by the nitrogen-atoms in the amino of HDA are attacked by Mn(OAc)2, and then the reactive intermediate, which acts as the nucleophile, attacks the carbonyl carbon of DMC to generate intermediate HMC and finally to HDC. (4) The kinetics model of methoxylcarbonylation of HDA with DMC using Mn(OAc)2 catalyst is studied in this thesis. It is found that higher temperature is beneficial to the conversion of HMC to HDC. The result shows that the activation energies of the two steps are Ea1=47.0514 kJ·mol-1 and Ea2=60.4504 kJ·mol-1, and the frequency factors are A1=1.4645×102 (mol/L)-3.5432?min-1 and A2=3.6519×104 (mol/L)-3.3226?min-1, respectively. 

Document Type学位论文
Recommended Citation
GB/T 7714
赵丽滟. 碳酸二甲酯(DMC)高效催化合成 1,6-六亚甲基二氨基甲酸甲酯(HDC)研究[D]. 北京. 中国科学院研究生院,2016.
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