水对脂肪酶非水相催化拆分2-辛醇的影响

利用假单胞菌脂肪酶在有机溶剂中催化的对映选择性酯化反应，对外消旋（Ｒ，Ｓ）－２－辛醇进行了动力学拆分，考察了水对脂肪酶非水相催化性能的影响．结果表明，酶在有机溶剂中的活力显著依赖于系统的加水量，二者呈钟罩形曲线，但最佳加水量范围以及酶的活力大小因溶剂不同而异；在最佳加水量范围内，系统含水量的变化对酶的对映选择性影响不大，但加水量增大（＞１％，Ｖ／Ｖ）会导致逆反应（酯的水解）加剧而降低醇的光学纯度；在反应进行一定时间后，添加分子筛移走酯化反应生成的水，可显著提高反应的转化率，并增大醇的对映体过量，但当超过快反应（Ｒ－醇的酯化）的平衡转化率时，反而会造成残留醇的光学纯度下降．用二甲基甲酰胺和乙二醇取代部分或全部的水添加于非水相酶反应系统，也能起到与水类似的甚至更强的激活酶的作用．     

固定化根霉细胞催化拆分(R,S)-环氧丙醇丁酸酯的研究

用聚乙烯醇包埋、硫酸钠固定法对根霉（ Ｒｈｉｚｏｐｕｓｓｐ．Ｂｃ０－０９）菌体细胞进行了固定化,所得凝胶具有良好的机械性和稳定性． 对固定化细胞催化（ Ｒ,Ｓ）－环氧丙醇丁酸酯水解反应的性能进行了研究． 对ｐＨ值的影响考察结果表明, ３０ ℃下, 反应初速度在ｐＨ 值为５．５ 时最大; 酶的立体选择性在ｐＨ值为５．５～６．０ 时最高, 对映体比率（ Ｅ值）为５７． 对温度的影响考察结果表明,ｐＨ 值为５．５, 反应初速度在５５ ℃时最大; 酶的立体选择性随温度升高而下降． 固定化细胞具有较好的操作稳定性．     

八羟基喹啉铁(Ⅱ)/MCM-41对苯酚羟化的催化作用

利用ＭＣＭ－４１中孔分子筛为载体，制备了负载型八羟基喹啉铁（Ⅱ）／ＭＣＭ－４１（简记为Ｆｅ（Ⅱ）－Ｑｘ／ＭＣＭ－４１）催化剂．ＸＲＤ，ＩＲ证明八羟基喹啉铁（Ⅱ）配合物成功地负载于ＭＣＭ－４１分子筛中．考察了八羟基喹啉铁（Ⅱ）／ＭＣＭ－４１对苯酚羟化反应的催化作用，和未负载的配合物相比，苯酚的转化率、对苯二酚的选择性以及Ｈ２Ｏ２的利用率都有显著的提高．同时也探讨了温度、反应介质及介质ｐＨ值对苯酚羟化反应的影响．结果表明，随着温度的提高，苯酚的转化率增加，但温度太高，易导致副产物增多；有机溶剂不利于羟化反应的进行，水是实验条件下苯酚羟化反应的最佳反应介质；在一定程度上，ｐＨ值越低，越有利于反应活性的提高，若ｐＨ值太低，活性反而下降，ｐＨ值升高不利于苯酚羟化反应的进行．该催化剂也具有较高的稳定性．     

水溶性铑－膦配合物催化1－十二碳烯常压氢甲酰化反应研究

本文研究了水溶性铑配合物ＲｈＣｌ（ＣＯ）（ＴＰＰＴＳ）２在常压（ＣＯ：Ｈ２＝１：１）条件下对１－十二碳烯氢甲酰化反应的催化性能，并对催化剂浓度、表面活性剂浓度、溶液ｐＨ值、膦铑比、溶剂等因素的变化对催化活性的影响作了考察．结果表明，表面活性剂（ＣＴＡＢ）的加入，可以在反应体系中形成胶束．加速有机相和水相间的传质速度，从而提高催化转化速度．在反应温度（８０℃）下，ＣＴＡＢ的临界胶束浓度（ＣＭＣ）较室温下高．达到最佳催化活性的ｐＨ范围为７～９，［Ｐ］／［Ｒｈ］比为１６，而有机溶剂的加入则使转化数降低．     

有机溶剂-水双液相体系脂肪酶不对称水解合成S-(+)-萘普生

采用有机溶剂－水双液相体系作为反应介质，并用键合有—Ｃ６Ｈ５的无定型多孔硅胶作为分散剂增大两相间的接触面，用圆柱状假丝酵母脂肪酶对萘普生甲酯进行不对称水解．考察了酶浓度、体系ｐＨ值、温度、分散剂对反应的影响．当转化率为２４．３％时，产品萘普生的对映体过量值（ｅｅ）为９４．９％，剩余底物萘普生甲酯的对映体过量值（ｅｅ）为３０．５％，当以异辛烷作为有机相时，该体系酶催化水解的对映体比率（Ｅ）约为５０．     

固定化米曲霉催化拆分丙氨酸消旋体的反应特性

研究了溶液ｐＨ、搅拌强度，催化剂用量、底物浓度及产物浓度对固定化米曲霉催化拆分Ｎ－乙酰－ＤＬ－丙氨酸反应的影响。结果表明，低底物浓度（Ｓ〈０．２ｍｏｌ／Ｌ）时反应符合Ｍ－Ｍ方程，底物浓度Ｓ〉０．２ｍｏｌ／Ｌ时，有底物抑制现象，当产物浓度Ｐ〉１０ｍｍｏｌ／Ｌ时反应存在产物抑制现象。     

Cp2TiCl2/n-BuLi催化体系在烯烃加氢反应中的催化活性和稳定性

研究了Ｃｐ２ＴｉＣｌ２／ｎ－ＢｕＬｉ催化体系和构成和Ｔｉ浓度与其催化烯烃加氢反应活性和稳定性的关系。考察了不同结构的烯烃，反应温度和度物浓度对该体系催化性能的影响。结果表明，在高的ｎ（Ｌｉ）／ｎ（Ｔｉ）值和低催化剂浓度时，可得到很高的催化活性。     

金属离子与卟啉的嵌入反应动力学研究（Ⅵ）：——乳酸缓冲体…

研究了在３５±０．１℃、离子强度０．５ｍｏｌ／Ｌ（ＫＣｌ）下，乳酸根催化Ｃｕ＾２＋离子嵌入溴化间－四（Ｎ－乙酸甲酯基－３－吡啶基）卟啉和溴化间－四（Ｎ－氰乙基－３－吡啶基）卟啉的反应动力学。根据催化剂浓度、溶液的ｐＨ值与反应速率间的关系。得到Ｃｕ＾２＋离子嵌入该类卟啉的反应动力学方程。。实验结果表明，该类反应遵循负离子催化卟啉变机理，变形的卟啉及其与乳酸根离子的缔合物为可能的活性中间体。     

水溶性钯－膦配合物催化1－己烯加氢反应研究

研究了水溶性钯－膦配合物ＰｄＣｌ２（ＴＰＰＴＳ）２催化１－己烯加氢反应，考察了两相催化体系中添加表面活性剂ＣＴＡＢ，膦配体ＴＰＰＴＳ，以及溶液ｐＨ值等对反应的影响，证明了１－己烯加氢反应中有一诱导期．反应中涉及两种催化活性物种．一种是由ＰｄＣｌ２（ＴＰＰＴＳ）２还原生成的低氧化态催化物种，它在一定的ＣＴＡＢ浓度下，可以保持相当的稳定性．另一种是被ＴＰＰＴＳ或Ｈ２还原形成的钯黑．根据ＰｄＣｌ２和ＴＰＰＴＳ反应过程的３１ＰＮＭＲ研究，对ＰｄＣｌ２（ＴＰＰＴＳ）２分子中Ｐｄ被还原和ＴＰＰＴＳ被氧化提出了解释     

有机溶剂/缓冲液双相体系中绿豆环氧化物水解酶催化环氧苯乙烯不对称水解反应

研究了有机溶剂/缓冲液双相体系中绿豆环氧化物水解酶高立体选择性地催化外消旋环氧苯乙烯水解生成(R)-苯基乙二醇反应.结果表明,与单水相反应体系相比,有机溶剂/缓冲液双相反应体系不仅有效地抑制环氧苯乙烯的非酶水解反应,而且明显提高底物的浓度,产物的收率和ee值更高.在所考察的不同有机溶剂中,正己烷不仅能较好地溶解底物,而...     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

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%.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

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.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

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.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

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.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

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.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

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.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

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.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

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.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

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.