甲醛和甲酸甲酯缩合制乙醇酸甲酯和甲氧基乙酸甲酯的研究

【作者】 杨天宇；

【导师】 陈樑；

【作者基本信息】 昆明理工大学 ， 应用化学， 2004， 硕士

【摘要】 甲醛和甲酸甲酯是重要的一碳化工原料，由它们出发可以合成许多新的化工产品，其中甲醛和甲酸甲酯经缩合反应合成乙醇酸甲酯及甲氧基乙酸甲酯，再进一步加氢制备乙二醇，是当前正在研究的非石油路线合成乙二醇的一条非常重要的路线。本论文对乙醇酸甲酯的性质、应用及目前国内外的研究进展做了详尽综合的介绍。针对甲醛和甲酸甲酯缩合生成乙醇酸甲酯的反应，研究了以硅钨酸为主催化剂，辅加液体酸组成的二元催化体系对反应的影响，并得到较好的合成乙醇酸甲酯工艺条件，产品的定量分析方法和相关的理论。 在硅钨酸中添加液体酸的二元催化剂体系中，不同催化剂比例、反应温度、原料配比、反应时间，对目的产物的收率和选择性都有一定的影响。研究证明，液体酸的加入有利于增加目的产物的收率。其中，浓硫酸的加入对目的产物收率的影响最大，适量添加30％硫酸，可使乙醇酸甲酯和甲氧基乙酸甲酯的收率分别达到6.35％和11.57％分别增加了1.28倍和2.01倍。催化剂中添加硫酸促进了甲酸甲酯的分解，可将系统由甲酸甲酯和聚甲醛分解升压时间由98min缩短到72min。二元催化体系中添加过磷酸或甲烷磺酸也可不同程度的提高目的产物的收率，但相对添加硫酸，二者对目的产物收率提高的影响较弱。由研究还得出如下结论：添加了液体酸后，可使反应温度降低；增大原料配比目的产物的收率增加；反应时间为3～4h。 本研究建立的反应醇解母液气相色谱分析方法，能进行定性定量分析。在稳定的色谱条件下，参考色谱图，用已知纯物质对照，由保留时间定性。模拟醇解反应母液浓度，用各组分的纯试剂配制标准混合溶液，确定了乙醇酸甲酯的浓度色谱分析校正方程y=5.9267lnx+1.4406，以及甲氧基乙酸甲酯的浓度色谱分析校正方程y=8.2344lnx-5.5652，两方程的相对误差均小于2％。应用这两个方程可计算得出产物中乙醇酸甲酯和甲氧基乙酸甲酯的实际浓度。 本文还对二元催化体系的催化反应机理进行了探讨。将单一催化体系(即纯杂多酸催化)的催化反应机理和添加液体酸后的二元催化体系的催化反应机理做了比较。经比较得出，杂多酸对反应的催化，主要是以酸碱协同的方式进行，缩合反应可以在催化剂体相进行，杂多阴离子可起到稳定中间体作用。添加液体酸后，有利于固体酸和气体的接触，起到了一定的溶剂作用。硫酸本身昆明理工大学硕士学位论文摘要对反应有很好的催化作用，增加了产物的生成途径，其给出的H十离子与拨基氧作用，削弱了锁基氧对经基氢的吸引力，使乙醇酸甲酷不易被离子化而脱掉处于活化状态的甲酸基HC二O·，生成质子化的甲酸甲酷，稳定了气相中的乙醇酸甲醋。更多还原

【Abstract】 Formaldehyde and methyl formate are fundamental raw materials in Cl chemical technology as many kinds of chemicals can be produced from them. From the condensation of formaldehyde and methyl formate, methyl glycolate and methyl methoxy acetate can be synthesized efficiently, and both of them can be used for producing ethylene glycol, this way is of great importance. Condensation of formaldehyde and methyl formate to methyl glycolate and methyl methoxy acetate is studied in this paper. The the influence of binary-catalyst-system - which is the mixture of heteropoly acid and liquid acid, to condensation is discussed, and proper reaction conditions of this react are gotten. The quantity test method of the product and relative theory are also given.Silicotungstic acid mixed with liquid acid to catalize the condensation is mainly studied. Reaction conditions such as the catalyst ratio, reaction temperature, molar ratio of FA and MF and the reaction time are influenced the ratio and selectivity of product to a certain extent. It is found that add proper amount liquid acid can increase the yield of MG and MMA. Among those liquid acid, sulfric acid showed the greatest influence on the yield. Just add 30% sulfric acid can increase the yield of MG and MMA to 6.35% and 11.57% respectively. sulfric acid can stimulate the decompose of MF and cut the time of pressure increasing from 98min to 72min. Add polyphosphoric acid or methanesulfonic acid can also increase the yield of MG and MMA. But contrast to sulfric acid the influence are relative weak. The experiment also indicate that after adding liquid acid reaction temperature decreased slightly, the yield increased while rising molar ratio of FA and MF, and reaction time could be controlled under 3-4 h.The method of methanol treated reaction moist analysed by using the Gas Chromatograph is build in this paper, which can carry out quantity and qualitaty test. Under stable condiction, methanol treated reaction moist is qualitative analysized by compared with the retention time of pure samples. Based on the concentration range of methanol treated reaction moist, the standard mixture is confected. In the consequence, the concentration emendate equations for MG andMMA are set up. They are y =5. 9267 ln x + 1.4406 for MG and y -8.2344 Inx-5.5652 for MMA. The relative error of both equation is less than 2%. By using these two equations, the conent is calculated.The reaction mechanism of binary-catalyst-system is explored also. Compared single-catalyst-system and binary-catalyst-system, heteropoly acid mainly act under the effect of acid-base synergistic. The anions of heteropoly acid can stabilize the intermediate. Liquid acid can benfit to the contact of heteropoly acid and react gas. H+ given by sulfric acid acted with =O, stabilized MG in the gas phrase.更多还原