烟酸的合成及其铬盐制备的研究

【作者】 吴浩；

【导师】 蒋丽红；

【作者基本信息】 昆明理工大学 ， 应用化学， 2006， 硕士

【摘要】 烟酸是一种重要的有机合成原料，用途广泛，其应用领域覆盖医药、食品、饲料添加剂以及化工助剂等行业，国内外市场对烟酸的需求逐年增加。烟酸铬是一种重要的补铬产品，随着社会的发展和人民生活水平的提高，烟酸铬的需求量逐年增加。烟酸的合成及烟酸铬的制备一直是研究者关注的一个课题。本论文对现有高锰酸钾氧化合成工艺条件进一步优化，提高了产品收率。同时也对二氧化硒氧化合成方法进行了研究，得到了适宜的工艺条件，并对氧化剂的循环使用和反应的动力学进行了研究，同时对烟酸铬的制备进行了研究，并研究了产品中铬含量的测定方法，具体工作分四部分：1．高锰酸钾氧化3—甲基吡啶制烟酸及产品分离工艺条件的考察，重点对反应温度，溶液pH值，氧化剂加入方式和结晶条件进行了优化，产品最终收率达到88.4％。二氧化硒作为一种温和的氧化剂，在氧化反应中具有良好的选择性，通过对二氧化硒氧化合成法的研究，得到了适宜的反应条件：3—甲基吡啶与二氧化硒摩尔比为1：1.6，以吡啶为溶剂，3—甲基吡啶浓度2mol／L，反应温度130℃，反应时间2h，产品收率达到40.1％。通过考察影响烟酸铬配合反应的因素，得出最优的反应条件为：烟酸与氢氧化钠摩尔比为1：1，烟酸与三氯化铬的摩尔比为3.2：1，三氯化铬溶液浓度3.3mol／L，滴加速度7mL／h，反应温度73℃，。反应前溶液的pH值为7.4～7.6，反应后溶液的pH值在6.8～7.0之间。在此反应条件下，所得产品的铬含量平均值为12.35％，产品平均收率达到92.4％。2．二氧化硒作为氧化剂与高锰酸钾相比价格较高，所以二氧化硒的氧化再生循环利用也是本论文研究的内容之一。实验中采用硝酸作氧化剂氧化单质硒实现二氧化硒的再生，并确定了适宜的工艺条件：单质硒与硝酸的摩尔比1：4.2，硝酸浓度5.5mol／L，反应温度95℃，反应时间3h，产品收率达到97.8％。3．本论文对二氧化硒氧化3—甲基吡啶反应的动力学进行了研究，建立了反应的动力学模型。研究结果表明，此反应在研究条件范围内为二级反应，反应速率常数与温度的关系式为：k=1.519×10¹⁵exp（-136.53×10³／RT）。4．对产品中铬含量的测定方法进行了研究，通过对原子吸收光谱法和滴定分析法的比较，最终确定了滴定分析法—过硫酸铵氧化容量法的可行性。更多还原

【Abstract】 Nicotinic acid is a kind of important organic synthesis raw materials, and used in a wide range, for example, medicine, food, feed additive and chemical auxiliary, etc. The demands to nicotinic acid are increasing year by year in domestic and international market. Chromium nicotinic acid is a kind of important benefit chromium products. With the development of society and improvement of level of people’s life the demands to chromium nicotinic acid are increasing year by year. Nicotinic acid and chromium nicotinic acid is one of the subjects that researcher pay close attention to.The thesis includes four parts: Synthesis process conditions of nicotinic acid with 3-picoline oxided by potassium permanganate that process conditions were further optimized. The synthesis of nicotinic acid used selenium dioxide as oxidant was studied. The kinetics was researched. The recycling use of oxidant was researched. The synthesis of chromium nicotinic acid was studied; the analysis method of product was determined.1. Process conditions of synthesis and the method of purification of products that nicotinic acid through 3-picoline oxided by potassium permanganate was searched. Reaction temperature, the pH of solution, the way of potassium permanganate joined and crystallization condition were further optimized. The yield was up to 88.4%. Selenium dioxide is one of the gentle oxidant having good alternatives. Synthesis of nicotinic acid used selenium dioxide as oxidant was studied. The suitable reaction condition was that the mole ratio of 3-picoline / selenium dioxide was 1:1.6, pyridine was used as solvents, the concentration of 3-picoline was 2mol/L, reaction temperature was 130 ℃, reaction time was 2h, products yield was up to 40.1%. Synthesis of chromium nicotinic acid was carried on. The suitable reaction condition was that the mole ratio of nicotinic acid /sodium hydroxide was 1:1, and the mole ratio of nicotinic acid /chromic was 3.2:1, the concentration of 3-picoline was 3.3mol/L reaction temperature was 73℃, the acceleration of dripping was 7mL/h, the pH of solution was 7.4-7.6 before reacting, the pH of the solution was 6.8-7.0 after reacting. Under this reaction condition, end-resulting products chromium content was 12.35%, average product yield was up to 92.4%.2. The recycling use of oxidant was researched. The suitable reaction condition was that the mole ratio of selenium/ nitric acid was 1:4.2, the concentration of nitric acid was 5.5mol/L, reaction temperature was 95℃, reaction time was 3h, the yield was up to 97.8%.3. Kinetics of oxidation of 3-picoline by selenium dioxide was studied. It was deduced that the reaction follows second-order kinetics in the range condition studied and the relationship between reaction rate constant and temperature wask =1.519×10¹⁵ exp（-136.53×10³/ RT）4. The analysis method of content to chromium nicotinic acid through Atomic Absorption Spectroscopy and oxidation of ammonium persulfate was researched. The method of oxidation of ammonium persulfate was confirmed to be feasible更多还原