| 题名 | 甘油间接合成1,3-二羟基丙酮的研究 |
| 作者 | 向华明 |
| 学位类别 | 硕士 |
| 答辩日期 | 2015-06-01 |
| 授予单位 | 中国科学院大学 |
| 授予地点 | 北京 |
| 导师 | 文彬 |
| 关键词 | 甘油 1,3 -二羟基丙酮 间接法 基团保护 |
| 学位专业 | 材料工程 |
| 中文摘要 | 甘油作为生物柴油生产过程的副产物，随着生物柴油产业的大力发展已经出现过剩的情况。将廉价的甘油衍生为具有商业价值产品的研究正蓬勃发展，其中，氧化甘油的仲羟基以合成1,3-二羟基丙酮（DHA）是一个国际性的科研热点。直接氧化甘油的仲羟基得到1,3-二羟基丙酮比较困难，因为甘油具有三个羟基，易产生过度氧化导致选择性不高。目前国内外工业生产1,3-二羟基丙酮的主要方法是通过氧化葡萄糖杆菌发酵制得，该反应过程条件苛刻，反应时间较长，分离提纯难度大，产率很低；利用催化剂氧化甘油制1,3-二羟基丙酮的报道包括Au/C 或Au-Pd/C等催化剂，这类催化剂通常是比较昂贵的过渡金属，在反应过程中会产生副产物所以选择性不高，反复利用时也会产生金属流失。在目前研究的基础上，本论文设计了一条保护基团的间接合成路线，包含伯羟基缩醛保护、仲羟基氧化、水解还原端羟基三步，达到了高的转化率和选择性。1、甘油与苯甲醛的缩醛反应。缩醛反应传统的催化剂是质子酸，如HCl 和H2SO4，但是产生的大量废物对环境污染严重，并有腐蚀设备，发生副反应等缺点，因此固体酸用于液相催化反应也得到了发展，但固体催化剂容易结焦失活。本文制备了对甲苯磺酸铜，替代腐蚀性强、副反应多的质子酸作为催化剂，用于催化甘油和苯甲醛缩合反应，取得了较好的结果，且催化剂可重复使用。利用响应面分析法对工艺条件进行了优化，得出最佳工艺条件为：n(甘油)/n(苯甲醛)=1.3，V(石油醚)/V(苯甲醛)=1.3，催化剂用量为苯甲醛物质的量的0.9%，缩醛收率为96.0%。但该缩醛是两种物质的同分异构体混合物，对其分离具有一定的难度，本论文利用五元环和六元环之间的质子酸催化转化机理，首先使五元环向六元环转化，之后以甲苯为溶剂，在-20℃的条件下，通过结晶法高收率地分离出了顺式六元环缩醛2-苯基-1,3-二氧六环-5-醇中间产物。2、2-苯基-1,3-二氧六环-5-醇的氧化。第二步是氧化羟基，即将2-苯基-1,3-二氧六环-5-醇的羟基进行氧化生成2-苯基-1,3-二氧六环-5-酮。考虑到缩醛对酸很敏感，因此必须谨慎地选择氧化体系，通过对常用的锰化合物氧化剂、铬化合物氧化剂、过氧化物氧化剂、含卤氧化剂的筛选。最后发现2,2,6,6-四甲基哌啶-氮-氧化物（TEMPO）在NaClO作为助催化剂时能很好的氧化缩醛。该反应条件温和，呈碱性，且PH可调节，当TEMPO、NaBr、NaClO的组成为0.02eq:0.1eq:1.5eq（相对于原料的摩尔比例）的时候，经过30min的氧化反应，转化率为98.16%。3、2-苯基-1,3-二氧六环-5-酮水解生成1,3-二羟基丙酮。水解过程比较简单，目标产物立刻溶于水相进一步促进了水解的进行。难点在于对产物的分离。如果用盐酸作为水解催化剂，反应后水相中除产物外还有盐酸和少量苯甲醛，苯甲醛可用正己烷萃取，水可通过蒸馏除去，但温度过高盐酸浓缩，酸度加大会产生碳化，温度过低除水过程又非常缓慢。采用固体酸——Amberlyst-15作为催化剂，比盐酸具有明显的优势，不仅催化性能良好，高温下也能避免副反应的发生，而且过滤就能直接回收利用。通过优化，Amberlyst-15用量为0.5g、反应时间1.5h，水解后得率为67.5%。本文设计了一条由甘油间接合成1,3-二羟基丙酮的高收率工艺路线，并对该过程进行了系统研究，比起生物发酵法具有更高的产率，且反应条件温和，操作简单，成本更低。更重要的是，原料甘油来源于动植物油脂，使工艺具有很强的工业和社会价值。 |
| 英文摘要 | Glycerol is large surplus with the development of biodiesel industry, which formed as a by-product during the production of biodiesel. Research efforts to find new applications of glycerol as a low-cost feedstock for functional derivatives have led to the development of a number of selective processes for converting glycerol into commercially valued products. Oxidation of the secondary hydroxyl-group yields the important fine chemical 1,3-dihydroxyacetone (DHA), which has become an international research hotspot. However, Good selectivity to 1,3-dihydroxyacetone at high glycerol conversion is difficult to achieve because of the tri-hydroxyl structure of glycerol and rapid over oxidation of 1,3-dihydroxyacetone. 1,3-dihydroxyacetone is currently produced by microbial fermentation of glycerol over Gluconobacter oxydans. The productivity, however, is relatively low due to the strict fermentation conditions and long fermentation time, also, it is hard to separate the target product. Efforts to obtain 1,3-dihydroxyacetone include the use of catalysts, such as Au/C or Au-Pd/C catalyst, which are expensive and a large number of by-products are often formed which decrease the selectivity. Furthermore, the catalyst is lost after reused. In the work of here, an indirect conversion route was designed, which include acetalization, oxidation and hydrolysis. 1、Condensation of glycerol with benzaldehyde. Traditionally, bronsted acid catalysts such as HCl and H2SO4 are commonly used in the industry. However, the generation of large volumes of toxic waste which poses environmental risk. The corrosion of equipment and by-production are some of the drawbacks of these catalysts. Therefore, the development of solid acid catalysts for liquid phase reactions is desired, but solid acid catalysts showed significant deactivation during the reaction by coking. Copper p-toluenesulfonate was prepared for replacing the bronsted acid, which has a strong corrosive and many side effects. It can be employed as the catalyst for the condensation of glycerol with benzaldehyde and reached a good result. Also, the catalyst can be reused. By optimizing the process with response surface methodology, the procedure was as follows. The molar ratio of benzaldehyde to glycerol was 1:1.3, the volume for petroleum ether was 1.3 times of benzaldehyde and the dosage of catalyst was 0.9mol% of benzaldehyde. The yield of benzaldehyde glycerol acetal showed the maximum conversion of 96.0%. The acetal was an isomer mixture of two kinds of substance. Direct separation of an isomer mixture is difficult. It was noticed that the bronstedacid-driving mechanism transformation between isomers by taking toluene as solvent. After transfer five ring to six ring, the high value of cis six-member ring was separated out extensively by crystallization under low temperature (about -20°C). 2、Oxidation of the 2-Phenyl-1,3-dioxan-5-ol. The second step of this process is the oxidation of hydroxyl groups, the acetalized glycerol 2-Phenyl-1,3-dioxan-5-ol can be oxidized thoroughly to the corresponding acetalized dihydroxyacetone (2-phenyl-1,3-dioxan-5-one) under mild condition without over-oxidation. Considering acetal is very sensitive to acid, it must be careful to choose oxidant. The common oxidants include manganese compounds, chromium compounds, peroxide and halogen-oxidant were studied., experimental result shows that the acetalized glycerol can be oxidized by 2,2,6,6-Tetramethyl-1-piperidinyloxy(TEMPO) efficiently with NaClO as the auxiliary oxidant. The reaction condition is mild and PH can be adjusted. When the molar ratio was n(TEMPO): n(NaClO): n(NaBr) = 0.02: 0.1: 1.5, The yield of oxidation achived.at 98.16% through 30 minutes oxidize. 3、hydrolysis of 2-phenyl-1,3-dioxan-5-one to obtain 1,3-dihydroxyacetone. The hydrolysis process is simple, because the product 1,3-dihydroxyacetone dissolved in water phase immediately, which can promote the hydrolysis. On the contrary, separating 1,3-dihydroxyacetone is relatively difficult. When using HCl as catalyst , the HCl will stay in the water phase. Benzaldehyde, which in water phase can use n-hexane to extraction, water can be removed by distillation. But when the temperature is high, the concentrated HCl bring carbonization, the low temperature is bad for removing water. Studies showed that the water-insoluble acid (Amberlyst-15), Amberlyst-15 is better than HCl due to its none-by-production and highly selective properties. Just filtering, it can be reusable. When the usage is 0.5g, the yield of hydrolysis is 67.5%, after 1.5h reaction. We designed an efficient route capable of producing 1,3-dihydroxyacetone from glycerol in high yield. It is better than microbial fermentation process. It can process in mild condition, the operation is simple and the cost is low. More important, glycerol derived from plant and animal oils and fats, the process has a strong industrial and social value. |
| 公开日期 | 2015-06-15 |
| 内容类型 | 学位论文 |
| 源URL | [http://ir.xjipc.cas.cn/handle/365002/4227]  |
| 专题 | 新疆理化技术研究所_资源化学研究室 |
| 作者单位 | 中国科学院新疆理化技术研究所 |
| 推荐引用方式 GB/T 7714 | 向华明. 甘油间接合成1,3-二羟基丙酮的研究[D]. 北京. 中国科学院大学. 2015. |
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