2-甲基吡啶和4-甲基吡啶合成工艺研究

以乙醛与氨为原料在常压下反应合成2-甲基吡啶和4-甲基吡啶．较佳反应条件为：反应温度为380℃,乙醛与氢物质的量比为3．0：2．0,收率可达50％以上．反应生成的混合2-MPD和4-MPD水溶液通过萃取、精馏可制得2-甲基吡啶(≥99．0％)和4-甲基毗啶(≥98．5％)成品。此工艺路线步骤简单、收率高、易于操作、适宜工业化。     

2-氯-5-三氯甲基吡啶分离提纯的研究

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。     

3-甲基吡啶和4-甲基吡啶的分离技术进展

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。     

2-氯-5-氯甲基吡啶的合成

对环戊二烯-丙醛法合成2-氯-5-氯甲基吡啶进行了实验研究,并通过正交实验优化了其关键步骤的合成条件.     

2-甲基吡啶合成2-乙烯基吡啶

以二苯胺生产过程中产生的副产物2-甲基吡啶为原料,以KOH改性的HZSM-5沸石分子筛为催化剂,气相一步法合成了2-乙烯基吡啶。考察了催化剂的焙烧温度、用于改性的钾含量、成型过程中的粘结剂的种类和含量,反应的工艺条件等因素对反应的影响。实验结果表明,催化剂焙烧温度为550℃,改性钾离子的质量分数为3%,以硅溶胶作为粘结剂进行催化剂成型,硅溶胶的用量为K-HZSM-5质量的50%,当反应温度为360~370℃,原料2-甲基吡啶和甲醛摩尔比为1∶3,质量空速0.75 h-1时,2-甲基吡啶的转化率可达到80.26%,2-乙烯基吡啶的选择性可达到97.59%,实现了副产物的有效利用。     

3-甲基吡啶的合成

介绍了3-甲基吡啶应用及生产现状，综述了国内外以不同原料合成3—甲基吡啶的方法，包括分别以丙稀醛和氨；乙醇、甲醛和氨；乙醛、甲醛和氨；乙醛或三聚乙醛、甲醛、六次甲基四胺；丙烯醛、丙醛；三烯丙基胺；2—甲基戊二腈为原料的气固相接触催化法和以2—甲基戊二胺为原料的气液相催化法，重点介绍了以2—甲基戊二腈为原料制备3—甲基吡啶的生产工艺。     

2-氯-5-三氟甲基吡啶和3-三氟甲基吡啶的制备

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。     

2-氯-5-甲基吡啶生产工艺改进

针对由3-甲基吡啶-N-氧化物与三氯氧磷反应生产2-氯-5-甲基吡啶过程中存在的收率偏低问题,通过添加助剂三氯化铝,使合成收率达到了68%.与原有工艺相比,合成收率提高了16%,有效地降低了生产成本,具有生产应用前景.     

N-甲基-2-氯-5-吡啶甲基胺的高效液相色谱分析

采用高效液相色谱法分析N-甲基-2-氯-5-吡啶甲基胺,使用反相柱和可变波长紫外检测器,以乙腈 氯仿 水为流动相,外标法对N-甲基-2-氯-5-吡啶甲基胺的有效成分进行定量分析。其标准偏差为0.31%,变异系数为0.32%,平均回收率为100.17%。     

2-氯-5-甲基吡啶的合成

主要介绍了以2-氨基-5-甲基吡啶为原料,经重氮化合成2-氯-5-甲基吡啶的过程及影响因素.     

Vanadia-molybdena catalysts for the oxidation of 2-picoline

A study has been made of the influence of catalyst composition on the gas phase oxidation of 2-picoline over mixed vanadium and molybdenum oxides supported on kieselguhr. It is shown that the formation of partial oxidation products is associated with the existence of a mixed oxide phase. The selectivity for the formation of pyridine-2-aldehyde reaches a maximum when one in six vanadium(V) ions in the V₂O₅ lattice is replaced by a molybdenum(VI) ion. It is suggested that the origin of the selectivity is the formation of isolated (V⁴⁺-O) species.     

V-Ti-O催化剂上一步氧化合成异烟酸

利用浸渍法制备的V-Ti-O催化剂催化氧化4-甲基吡啶一步合成了异烟酸.对催化剂进行了XRD表征,并采用液相色谱、红外等手段分析异烟酸产品.考察了V负载量、助剂、反应温度、空速以及进水量对催化剂性能的影响.结果表明:酸性氧化物助剂利于提高催化性能,碱性氧化物则会抑制催化活性.V/Ti(原子比)、反应温度和进水量对异烟酸产率有显著影响.在V-Ti-Cr-Al-P催化剂上,当V/Ti为0.21,反应温度310℃,4-甲基吡啶液体积空速小于0.3 h-1,空气/水/4-甲基吡啶(摩尔比)为96/70/1时,异烟酸的产率可以达到82%.     

Partial miscibility in water-nicotine and water β-picoline systems

The significant structure theory of liquids has been applied to the partially miscible systems, of which the temperature-composition phase diagrams are of closed loop type. In this paper, the sublimation energy of a mixture is expressed as a quadratic form of surface area fractions of components, and the energy correction parameter between one component and the other is assumed to be a second order function of temperature for simplicity, although it is a higher order function of temperatures and compositions. The calculated partial miscibilities are in good agreement with the experiment. Considered mixture systems are water-nicotine and waterβ picoline systems.     

Adsorption of γ-picoline onto acid-activated bentonite from aqueous solution

The adsorption of γ-picoline onto acid-activated bentonite was investigated. The adsorption reached a maximum at pH = 7. Pseudo-first-order, pseudo-second-order, the Elovich equation, and intraparticle diffusion models were used to analyze the kinetic data obtained at different concentrations. The pseudo-second-order model was best applicable to describe the adsorption of γ-picoline on acid-activated bentonite. The Langmuir model provided good correlation with the experimental data. The adsorption of γ-picoline was endothermic with ∆H° = 29 J/mol.     

Kinetics and mechanism of the vapour-phase ammoxidation of 4-picoline

The kinetics of the heterogeneous vapour phase ammoxidation of 4-picoline was studied over V₂O₅-Cr₂O₃-Al₂O₃ catalysts in a differential flow reactor between 548 and 598 K and under atmospheric pressure. The rate equation for the conversion of 4-picoline to isonicotinonitrile and the rate equation for the overall conversion of 4-picoline, represented the rate data satisfactorily. The overall conversion of 4-picoline was also tested by the Langmuir-Hinshelwood mechanism.     

奈韦拉平中间体2-氯-3-氨基-4-甲基吡啶合成工艺研究进展

综述了抗艾滋病药奈韦拉平中间体2-氯-3-氨基-4-甲基吡啶的合成方法研究进展.     

Side chain alkylation of 2-picoline with formaldehyde over alkali modified zeolites

The catalytic side-chain alkylation of 2-picoline with formaldehyde (37 wt/v) was studied over alkali and alkaline earth metal ion modified zeolites in vapor phase conditions at atmospheric pressure, and at a reaction temperature of 300°C. A mixture of vinylpyridine and ethylpyridine were formed by the alkylation of the corresponding picoline over Li, Na, K, Rb, Cs, Mg, Ca, Sr and Ba metal ion modified zeolites. The catalytic activity of side-chain alkylation of 2-picoline was studied over various alkali modified zeolite molecular sieves like ZSM-5 (SiO₂/Al₂O₃ = 30), X, Y, Mordenite and MCM-41. Alkali modified ZSM-5 (30) catalyst was found more active in side-chain alkylation of 2-picoline when compared to other zeolites. Among all these catalysts studied K modified ZSM-5 (30) and K-Cs-ZSM-5 (30) gave best conversion of 2-picoline and selectivity to vinylpyridine. Cs-ZSM-5 (30) and K-ZSM-5 (30) were employed to study the reaction parameters like reaction temperature, weight hourly space velocity, molar ratio, and time on stream for 2-picoline independently. The effects of alkali metal ion content (K, Cs) and precursors of potassium ion on catalytic activity in side-chain alkylation was studied. An attempt has been made to correlate between the basicity with the activity of side-chain alkylation. The bifunctional catalyst is required containing medium or weak acidic centers and basic centers in the side-chain alkylation, which is understood through proposed reaction mechanism. The selectivities of 2-vinylpyridine were 81.7, 90.8, and 94.8% at 65.4, 62.1 and 57.2% conversions at 300°C from 2-picoline and formaldehyde over K-ZSM-5 (30), Rb-ZSM-5 (30) and K-Cs-ZSM-5 (30) respectively. Indian Institute of Chemical technology (IICT) communication no: 020707     

Effects of 2-picoline on zinc electrowinning from acidic sulfate electrolyte

The behaviour of 2-picoline with and without antimony during electrowinning of zinc from acidic sulfate solutions was studied and was compared with that of gum arabic which is commonly used in industry as a levelling agent. The effects of these additives on current efficiency, power consumption, deposit quality, polarization behaviour, crystallographic orientation and surface morphology were determined. The addition of 2-picoline reduced current efficiency, increased power consumption and lowered the surface quality of electrowon zinc. Addition of antimony increased current efficiency, reduced power consumption and produced improved surface morphology and crystal orientations, (101) (112) (102) (103) (114) over a wide range of their combinations.     

间歇减压精馏分离2-甲基吡啶/2-羟乙基吡啶

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。