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正丁醚的制备是重要的大学有机化学实验,为提高学生对该实验所涉及的反应机理和关键操作要点的深入了解,采用Gaussian计算软件对正丁醇在酸催化下和无催化剂下的反应体系进行了研究,重点考察了酸催化下反应的主、副反应方向的反应机理。结果表明无催化剂下,正丁醇在常压液相下几乎不能发生反应;在酸催化下,正丁醇发生取代反应生成醚的反应路径是优势反应通道;酸催化下正丁醇的取代和消除反应速率常数均随温度增加而迅速增大,但消除反应的反应速率随温度增加更快,温度超过420 K消除反应将变得很明显,综合考虑,制备正丁醚的反应温度应控制在130~140 ℃之间较为合适。利用计算化学以图、表和动图等形式直观、动态、量化地解释了正丁醇成醚和成烯反应的竞争,该结果有助于更好地控制该反应体系,可用作实验教材的补充内容。 相似文献
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张国义付予锦吴金城徐新然秦明刚熊书书张仟春 《理化检验(化学分册)》2018,(10):1117-1121
基于正丁醚在纳米氧化锌材料表面的催化发光现象设计并制造了正丁醚催化发光传感器,并提出了一种快速测定空气中正丁醚的方法。在检测波长为440nm,反应温度为288℃,载气流量为280mL·min-1条件下,正丁醚的质量浓度在30.0~2 000mg·m-3内与其催化发光强度呈线性关系,检出限(3S/N)为12.0mg·m-3。将上述方法用于空气样品中正丁醚含量的测定,其测定结果与气相色谱-质谱法所得结果吻合。 相似文献
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△~1,~4-3-酮甾体与锌-硫酸在正丁醚中反应形成一种有特性的荧光,而△~4-3-酮甾体,A环饱和甾体和A环芳构化甾体均无荧光产生。此方法可用于定量测定微生物A环脱氢作用所形成的△~1,~4-3-酮甾体。 相似文献
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微波辐射下固体超强酸SO2-4/TiO2/La3+催化合成没食子酸正丁酯 总被引:2,自引:0,他引:2
没食子酸正丁酯为白色或淡褐黄色的结晶粉末,无臭,稍有苦味;难溶于水,易溶于乙醇,是一种油溶性的抗氧化剂,常作为食品稳定剂、感光材料添加剂等[1].没食子酸正丁酯可由没食子酸和正丁醇在硫酸催化下直接合成.硫酸催化活性高,价格低,但对设备腐蚀严重,副反应多,产率低,反应时间长,后处理比较困难.近年来有采用十二烷基苯磺酸、固体超强酸[2,4]等作为替代硫酸的催化剂.固体超强酸的应用研究进展较快,已从单一型向复合型发展.本文在微波辐射下用固体超强酸SO2-4/TiO2/La3+为催化剂由没食子酸与正丁醇合成没食子酸正丁酯,考察了反应条件对产品产率的影响,并对产品进行了IR分析. 相似文献
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12-钨磷酸的应用,近年来发展迅速,有从实验室合成转为工业生产的趋势。本报告从E.Drechsel法的以钨酸钠和磷酸氢二钠为原料,改为以活性粉状白钨酸为原料,与磷酸直接反应,即成12-钨磷酸溶液。这样便可以免除Drechscl乙醚萃取法中大量盐酸的使用。在提纯时,把在Drechsel方法中所用的乙醚,改为沸点高的正丁醚,配合适当少量的盐酸,可以得到相应的(钅羊)盐油状物。并由于该(钅羊)盐安定度较差,用水反萃取即可使12-钨磷酸转入水溶液,经过浓缩即可得到12-钨磷酸晶体。回收的正丁醚,毋需蒸馏,可以反复使用。 相似文献
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本文研究了三相催化剂聚苯乙烯负载聚乙二醇在苯乙腈(PAN)的α-丁基化反应中重复使用时催化活性下降的问题,比较了使用前后的红外光谱,发现催化剂使用后负载聚乙二醇的自由端羟基与正丁基结合形成醚,失去自由羟基,这是催化活性下降的主要原因。同时发现催化剂重复使用8次后负载的聚乙二醇并未从载体脱落。 相似文献
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用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%. 相似文献
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Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction
Laurent Gavara Thomas Boisse Jean-Pierre Hénichart Adam Daïch Philippe Gautret 《Tetrahedron》2010,66(38):7544-5571
In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments. 相似文献
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The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula. 相似文献
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Rebecca J. Burton Mandy L. CrowtherNeal J. Fazakerley Shaun M. FilleryBarry M. Hayter Jason G. KettleCaroline A. McMillan Paula PerkinsPeter Robins Peter M. SmithEmma J. Williams Gail L. Wrigley 《Tetrahedron letters》2013
The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines. 相似文献
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KMnO4-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields. 相似文献
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N. A. Nedolya 《Chemistry of Heterocyclic Compounds》2008,44(10):1165-1219
The review contains a concise historical account and information on the most significant researches undertaken by the staff
at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry
of Heterocyclic Compounds.
Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee.
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008. 相似文献
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Regiospecific and direct imidation of the methyl C(sp3)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products. 相似文献
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《Tetrahedron》2014,70(21):3377-3384
The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative. 相似文献
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Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields. 相似文献