硅氢加成反应高选择性合成甲基苯乙基二氯硅烷

研究了硅胶负载聚乙二醇铂催化苯乙烯与甲基二氯氢硅的硅氢加成反应,β-加成产物甲基苯乙基二氯硅烷的选择性为100%,10℃下反应8h苯乙烯转化率为96.0%.反应存在一个诱导期,温度等反应参数对诱导期有重要影响,40℃下反应的诱导期不到1h,并探讨催化剂的催化机理和目标产物高选择性的原因.     

Rh(PPh3)3Cl/有机融盐催化烯烃硅氢加成反应

研究了Rh(PPh₃)₃Cl/二烷基咪唑六氟磷酸盐或烷基吡啶六氟磷酸盐催化三乙基氢硅烷与烯烃的硅氢加成反应. 实验结果表明, 二烷基咪唑六氟磷酸盐或烷基吡啶六氟磷酸盐的存在既有利于提高加成反应的转化率和β加成物的选择性, 又有利于反应结束后产物与催化剂的分离. C₁₆PyPF₆作为催化剂的载体, Rh(PPh₃)₃Cl催化苯乙烯与三乙基氢硅烷加成反应的转化率为95.7%, β加成物的选择性为87.8%, α加成物的选择性为0.001%, 脱氢加成产物的选择性为9.2%. 同时, 此催化剂重复使用7次以后仍具有较高的活性.     

二苯基膦功能化氧化石墨固载铂催化剂的制备及其催化烯烃硅氢加成性能

以氧化石墨为载体,采用二苯基膦配体对其进行改性,再利用膦配体对Pt的螯合配位作用合成了氧化石墨固载膦铂配合物催化剂(GO-P-Pt),并采用元素分析、FT-IR、XRD等方法对催化剂进行了表征,考察了催化剂催化不同烯烃与三乙氧基硅烷的硅氢加成反应性能。结果表明,该催化剂对烯烃与三乙氧基硅烷的硅氢加成反应具有良好的催化活性,在100℃,反应180 min后,1-辛烯的转化率为94.6%,β-加成产物的选择性高达99.4%;当底物为芳香烯烃时,β-加成产物的选择性比脂肪烯烃低。此外,催化剂在重复使用4次之后,活性基本保持不变。     

二苯基膦功能化氧化石墨固载铂催化剂的制备及其催化烯烃硅氢加成性能

以氧化石墨为载体,采用二苯基膦配体对其进行改性,再利用膦配体对Pt的螯合配位作用合成了氧化石墨固载膦铂配合物催化剂(GO-P-Pt),并采用元素分析、FT-IR、XRD等方法对催化剂进行了表征,考察了催化剂催化不同烯烃与三乙氧基硅烷的硅氢加成反应性能。结果表明,该催化剂对烯烃与三乙氧基硅烷的硅氢加成反应具有良好的催化活性,在100℃,反应180min后,1-辛烯的转化率为94.6%,β-加成产物的选择性高达99.4%;当底物为芳香烯烃时,β-加成产物的选择性比脂肪烯烃低。此外,催化剂在重复使用4次之后,活性基本保持不变。     

Hβ分子筛在环己烷过氧化氢分解中的催化活性

 使用不含过渡金属的Hβ分子筛催化环己烷过氧化氢分解反应,考察了主要产物环己醇和环己酮随反应时间和温度的变化. 结果表明, Hβ分子筛具有很高的催化活性,其TOF值高达181.9 h-1, 与贵金属催化剂5%Ru/Al2O3相当. 在125 ℃下环己醇和环己酮的总选择性达84.6%. 反应的主要副产物为环己酮缩合和羰基加成产物.     

CeCl_3·7H_2O-NaI-SiO_2催化氨基苯硫酚与高位阻α,β-不饱和酮的迈克尔加成-缩合串联反应的研究

研究了复合型催化剂CeCl3·7H2O-NaI-SiO2催化氨基苯硫酚与高位阻α,β-不饱和酮(1a-1n)的迈克尔加成-缩合串联反应。结果表明,该催化剂能有效地催化高位阻α,β-不饱和酮与2-氨基苯硫酚和2-氨基-4-氯苯硫酚的迈克尔加成-缩合串联反应。其最优条件是:n(CeCl3·7H2O)∶n(NaI)∶n(SiO2)∶n(α,β-不饱和酮)=1∶2∶10∶2;溶剂为CHCl3,加热回流反应4h,反应收率较高(60%左右)。催化剂重复使用4次催化效果稳定。     

NiO-SiO2，NiO-Al2O3和NiO-Al2O3-SiO2催化剂上顺酐选择加氢性能的比较

以正硅酸乙酯和硝酸铝分别为硅源和铝源，硝酸镍为活性组分前驱物，采用溶胶-凝胶法制备了NiO-SiO2，NiO-Al2O3和NiO-Al2O3-SiO2催化剂。顺酐液相选择加氢活性和选择性评价结果表明：顺酐在三种催化剂上转化率都在99%以上，而产物的选择性有较大的差别，其中NiO-SiO2催化剂上γ-丁内酯的选择性达80.1%，NiO-Al2O3催化剂上丁二酸酐选择性达99%以上，NiOAl2O3SiO2催化剂上两种产物都有。XRD，TPR等体相结构和表面结构的表征说明，三种催化剂的相组成、NiO的分散性及与载体的相互作用存在明显差别，这些差别可能是造成不同选择加氢性能的原因。     

固载化AlCl_3催化剂上α-蒎烯异构化反应

分别以SiO2和γ-Al2O3为载体采用两步气相法制备了固载化AlCl3催化剂,并首次将其用于α-蒎烯液相异构化反应.结果表明,该催化剂对α-蒎烯异构化反应具有非常高的催化活性,其中AlCl3/SiO2催化剂在40oC反应时α-蒎烯转化率和主产物(莰烯、柠檬烯和异松油烯)选择性分别为98.4%和93.7%;AlCl3/γ-Al2O3催化剂活性更高,在30oC反应时,即可获得95.5%的α-蒎烯转化率和94.4%的主产物选择性.固载化AlCl3催化剂的高活性与其强酸性有关.     

Cu(PPh3)2BH4作还原剂制备PtCu/C催化剂催化烯烃硅氢 加成反应研究

采用湿法浸渍, Cu(PPh3)2BH4作为还原剂制备了负载型PtCu/C双金属催化剂, Pt∶Cu原子比为0.5～2.0. 用于苯乙烯与三乙氧基硅烷加成反应, Cu元素的引入使Pt/C催化剂的催化性能得到提高, 表现出比Speier催化剂、Karestedt催化剂和Pt/C催化剂更好的β-加成产物选择性. 催化直链烯烃与三乙氧基硅烷加成反应表现出优良的催化性能, 并且催化剂可重复使用.     

硅胶微球负载钛硅分子筛TS-1催化剂的制备及对苯氧化合成苯酚的催化性能

将硅胶微球浸渍于钛硅分子筛（TS-1）合成液中,经晶化、焙烧制得负载TS-1分子筛硅胶微球催化剂。 用XRD、IR和SEM测试技术对其进行表征,将其用于过氧化氢氧化苯合成苯酚的反应中。 结果显示,TS-1分子筛能够很好地负载于硅胶表面,晶化温度160 ℃,晶化时间72 h,焙烧温度550 ℃,焙烧时间6 h时,获得的催化剂显示良好的催化性能。 在苯和H2O2初始原料量分别为0.5和0.1 mol、催化剂加入量为8 g、反应温度为60 ℃条件下,经过3 h的反应,苯的转化率达到10.32%,苯酚选择性达到97.12%。 9次重复使用后的苯转化率为9.42%,苯酚选择性为93.14%。     

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%.     

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.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

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.     

Microwave-assisted copper-catalyzed stereoselective ring expansion of three-membered heterocycles with α-diazo-β-dicarbonyl compounds

Microwave-assisted copper-catalyzed ring expansions of three-membered heterocycles with α-diazo-β-dicarbonyl compounds were investigated. Thiiranes generated 3-acyl-5,6-dihydro-1,4-oxathiines in the presence of copper sulfate and trans-3-acyl-5,6-dihydro-1,4-oxathiines as stereospecific products for 1,2-disubstituted cis-thiiranes through an intramolecular S_N2 process. Oxiranes gave rise to 2-acyl-5,6-dihydro-1,4-dioxines under the catalysis of copper hexafluoroacetylacetonate and cis-3-acyl-5,6-dihydro-1,4-dioxines as stereospecific products for 1,2-disubstituted cis-oxiranes via an intimate ion-pair mechanism. The current method provides a direct and simple strategy in efficient preparation of 3-acyl-5,6-dihydro-1,4-oxathiines and 2-acyl-5,6-dihydro-1,4-dioxines, important agents in medicinal and agricultural chemistry, from readily available thiiranes and oxiranes, respectively.     

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.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).