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3-甲基吡啶和4-甲基吡啶的分离技术进展 总被引:1,自引:0,他引:1
3-甲基吡啶与4-甲基吡啶是生产高附加值精细化工产品的重要有机原料,广泛应用于医药、农药、染料、香料、饲料添加剂、食品添加剂、橡胶助剂及合成材料等领域。笔者综述了3-甲基吡啶与4-甲基吡啶混合体系的各种分离方法,并对其应用前景进行了展望。 相似文献
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采用间歇减压精馏法实现了2-甲基吡啶和2-羟乙基吡啶这一热敏性混合物的分离,并考察了投料组成与操作压力对减压精馏过程的影响。结果表明,高真空条件降低了塔釜温度从而避免了物料在塔釜中受热变性,对于热敏物料2-羟乙基吡啶,减压精馏过程中压力应控制在4325 Pa以下,此时塔釜产品2-羟乙基吡啶的质量分数均能大于97%,同时收率能保持在86%以上。在压力为1325 Pa时,不同投料组成下塔顶产品2-甲基吡啶的质量分数和塔釜产品2-羟乙基吡啶的质量分数均高于98%,两者的收率也均在85%以上,能够很好地满足工业生产要求。 相似文献
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叙述近年来国内外发展的新农药如氟虫腈、溴虫腈、七氟菊酯、四氟苯菊酯、氯氟吡氧乙酸、吡氟禾草灵等相关的含氟中间体的开发,包括对-三氟甲基苯胺、2,6-二氯-4-三氟甲基苯胺、2,6-二氯-4-三氟甲基苯肼、3,5-二氯-4-氨基-6-氟吡啶酚、2,3,5,6-四氟苄醇、2,3,5,6-四氟-4-甲基苄醇、2-氯-5-三氟甲基吡啶、2.3-二氯-5-三氟甲基吡啶和2-(对氯苯基)-5-(三氟甲基)吡咯-3-腈等合成方法和国内生产情况。 摘 要 改进了传统的气相法生产2-氯-5-三氯甲基吡啶,以较新颖的液相合成方法成功地合成出2-氯-5-三氯甲基吡啶,提高了产率,减少了反应时间,且条件较为温和,在化工生产中具有一定的指导意义,对于其他吡啶类化合物的氯化亦有一定的参考价值。 相似文献
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为了寻找一条合成2,6-二甲基-4-羟甲基吡啶的简单,经济的方法,本文以2,4,6-三甲基吡啶为原料,分别与间氯过氧苯甲酸、乙酸酐以及氢氧化钠经过3步反应,将原料从2,4,6-三甲基吡啶转变成相应的2,4,6-三甲基吡啶-N-氧化物、2,6-二甲基-4-羟甲基吡啶乙酸酯进而水解得到最终产物,总收率达51.2%。与文献合成方法相比,本法采用原料便宜,操作简单,收率高。 相似文献
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研究了以3-甲基吡啶、氟化氢和氯气为原料在流化床反应器中一步法气相氯氟化反应制备2-氯-5-三氟甲基吡啶和3-三氟甲基吡啶的工艺,并对催化剂进行了筛选和考评,发现CrO-Al、CrCl-Al的活性较佳。以CrO-Al为催化剂,空速为288 h-1,温度为300℃时,2-氯-5-三氟甲基吡啶和3-三氟甲基吡啶的总收率最高,为66.6%,且失活催化剂在350℃,氮气和空气的体积比为1:1的混合气体下再生后,其催化活性基本可以恢复,2-氯-5-三氟甲基吡啶和3-三氟甲基吡啶的总收率均保持在66%左右。根据实验结果提出了反应机理和结焦机理。对催化剂进行了BET、TG和NH3-TPD表征,发现催化剂失活的主要原因是积炭覆盖了催化剂表面以及孔道,使催化剂强酸中心大量减少所致。 相似文献
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2-氯-5-三氯甲基吡啶分离提纯的研究 总被引:1,自引:0,他引:1
2-氯-5-三氯甲基吡啶是重要的医药和农药中间体。研究用萃取、蒸馏以及柱色谱方法对3-甲基吡啶光氯化产物进行分离和提纯,制备高纯度的2-氯-5-三氯甲基吡啶。通过毛细管气相色谱检测纯度,结果表明产物纯度为99%以上。 相似文献
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通过循环伏安曲线测定,考察了Span 60(山梨糖醇酐单硬脂酸酯)对3-甲基吡啶电氧化的影响。正交实验确定的最佳反应条件是:n(3-甲基吡啶)/n(硫酸)=0.4,添加高于或接近临界胶束浓度的Span 60,反应温度15℃,阳极电位1.9~2.0 V,电解电量为理论电量的10%;其选择性可达85.46%,电流效率为48.69%,电流密度提高300 mA/cm2,并根据最佳反应条件进行外循环放大实验,其结果与小试基本相同。在选定的实验范围内,Span 60对3-甲基吡啶电氧化有明显的促进作用,有应用前景。 相似文献
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A process of separation of close-boiling mixture by reactive distillation, exemplified by 3-/4-picoline separation through complexation with trifluoroacetic acid, has been analyzed in detail by numerical simulation. In such a process, the separation selectivity is supplied by a reversible chemical reaction and a displacement agent is used to regenerate the isomers. Parameter sensitivity analysis has shown the fundamental role played by the displacement agent in the regeneration as well as in the separation when the two isomers have to be recovered with the same purity. Optimization has shown that the displacement agent should ideally have an affinity for the reactive agent intermediate between that of the isomers to be separated. This affinity is measured by the ratio of the relative volatility to the chemical selectivity. 相似文献
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The paper investigates the ability of activated carbons developed from coconut shell to adsorb α-picoline, β-picoline, and γ-picolin from aqueous solution. The developed carbons are designated as SAC (activated carbon derived from coconut shells with out any treatment) and ATSAC (activated carbon derived from acid treated coconut shells). The carbons were, characterized and utilized for the sorption of α-picoline, β-picoline, and γ-picoline at different temperatures, particle size, pH and solid to liquid ratio. All the studies were performed by batch method to determine various equilibrium and kinetic parameters. The Langmuir and Freundlich isotherm models were applied and the Langmuir model was found to best report the equilibrium isotherm data. The adsorption of α-, β-, and γ-picoline followed the pseudo-second order rate kinetics. On the basis of kinetic studies, various rate and thermodynamic parameters such as effective diffusion coefficients, activation energy and activation entropy were evaluated. It was concluded that in majority of cases, the adsorption is controlled by particle diffusion at temperatures 10° and 25 °C while at 40 °C it is controlled by film diffusion mechanism. Similarly at concentrations 25 and 50 mg/l the adsorption was governed by particle diffusion in most of the cases while at >50 mg/l it was film diffusion controlled. The overall capacity of ATSAC was higher than SAC. The sorption capacity of γ-picoline was found more followed by β-picoline and α-picoline. 相似文献
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采用高效液相色谱法建立了一种测定1%氯虫·噻虫胺颗粒剂中杂质3-甲基吡啶的定量分析方法。方法采用二极管阵列检测器(DAD),Zorbax Eclipse Plus-C18色谱柱,以乙腈/冰乙酸-乙酸铵水溶液为流动相进行梯度洗脱,流速为1 mL/min,在262 nm波长下对氯虫苯甲酰胺中杂质3-甲基吡啶进行定量分析。结果显示3-甲基吡啶质量浓度为0.095~3.8 mg/L时,方法的线性相关系数为0.9999,定量限为1.12 mg/kg,平均回收率为104.9%,说明该方法准确度高、定量限低,适用于氯虫苯甲酰胺产品中3-甲基吡啶的定量分析。 相似文献
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An overview of the fundamental studies on a new method of nicotinic acid synthesis by the gas phase catalytic oxidation of β-picoline by oxygen is presented. The nature of active component in vanadia catalysts and reactivity of vanadium species are considered. Common features and differences in the mechanistic steps of nicotinic acid formation on various catalysts investigated by in situ FTIR spectroscopy are discussed. Effects of the reaction mixture components on the yield of nicotinic acid are considered in detail. Attention is paid to the kinetic equations of β-picoline oxidation on vanadia-titania catalysts. 相似文献
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K.V. Narayana B. David Raju S. Khaja Masthan V. Venkat Rao P. Kanta Rao 《Catalysis Letters》2002,84(1-2):27-30
V2O5/MgF2 catalysts with V2O5 contents ranging from 2.1 to 15.7 wt% were prepared, and the influence of the V2O5 content of the V2O5/MgF2 catalyst on the structure and activity for the ammoxidation of 3-picoline was investigated. XRD data indicate that V2O5 is in a highly dispersed state though segregation of V2O5 into tiny crystallites occurs at and above 8 wt% V2O5. The 3-picoline ammoxidation activity increased with an increase in V2O5 content due not only to the species arising out of interaction of V2O5 and MgF2, but also to the presence of V2O5 microcrystals in the catalysts. 相似文献
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R. Prasad S. Mathews A. Garg 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1991,51(4):461-472
The kinetics of the catalytic transformation of 3-picoline to 3-cyanopyridine by nitric oxide (NO) have been investigated over nickel oxide-aluminium oxide catalyst (2NiO·Al2O3) in a differential flow reactor between 300 and 360°C. A maximum yield of 98% was achieved with a catalyst having a Ni: Al atomic ratio of 1:1 and preheated in the presence of air at 600°C for 24 h. The rate equation Rn = kpknPpPn/(kpPp + knPn) deduced, assuming a steady state involving a two-stage irreversible oxidation-reduction process, represented the data most satisfactorily for conversion of 3-picoline to nicotinonitrile. A tentative mechanism for the reaction is proposed. 相似文献