烯烃不对称双羟化反应中TentaGel树脂支载的可回收和重复使用的OsO_4催化剂研究

合成了在烯烃不对称双羟化反应中可回收和重复使用的TentaGel支载的OsO_4 催化剂。在DMF溶剂中，TentaGel HLBr与三乙胺反应生成季铵盐，在搅拌下后者与 K_2OsO_4饱和水溶液作用24 h，过滤，得TentaGel-OsO_4催化剂，用去离子水在索 氏提取器中连续提取24 h以除去吸附在TentaGel上未键合的K_2OsO_4。 TentaGel- OsO_4催化剂在反式-二苯乙烯的不对称双羟化反应中化学产率≥80%，立体选择性 ≥93% ee，而且连续使用五次，其催化活性不变。     

苯乙烯不对称三羰化反应一步合成手性2-氧代-3-苯基戊二酸二甲酯

以苯乙烯、甲醇和CO为反应物,首次采用双膦配体(S)-P-PHOS和乙酰丙酮钯原位制备的手性络合物新催化体系,以对苯醌作为氧化剂,对甲苯磺酸作助催化剂,在甲醇溶剂中进行不对称三羰化反应一步合成手性2-氧代-3-苯基戊二酸二甲酯.与现有文献结果相比,三羰化反应所需CO压力明显降低,条件较为温和.     

双二茂铁基醛亚胺钼（ＶＩ）配合物的合成及催化性能

通过二茂铁甲醛与丙二胺反应得到双二茂铁基醛亚胺配体N~1,N~3-双二茂铁亚甲基丙烷-1, 3-二胺(FcMP), FcMP与MoO_2Cl_2(THF)_2的四氢呋喃溶液作用, 合成了双二茂铁基醛亚胺钼(VI)配合物. 以配合物为催化剂, 叔丁基过氧化氢为氧化剂, 分别以苯乙烯和环己烯为底物, 考察了温度、时间、催化剂量及溶剂对于烯烃均相环氧化反应的催化性能的影响. 结果表明, 在最优实验条件下, 反应12 h, 环己烯的转化率为88%, 环氧环己烷的选择性为98%;苯乙烯的转化率为84%, 氧化苯乙烯的选择性为76%. 催化剂经简单分离可回收使用, 且催化活性基本保持不变. 同时对环氧化反应的机理进行了初步探讨.     

乙酰丙酮氧钒催化氧化α-蒎烯一步转化成龙脑烯醛

以乙酰丙酮氧钒为催化剂,过氧化氢为氧化剂,研究了由α-蒎烯直接合成龙脑烯醛的反应。考察了溶剂、温度、催化剂用量、反应时间等因素对催化性能的影响。结果表明,乙酰丙酮氧钒与H2O2反应得到的高价态V5+是优良的氧化还原-Lewis酸双功能催化剂,易使α-蒎烯经氧化、2,3-环氧蒎烷异构得到龙脑烯醛。在n(H2O2):n(α-蒎烯):n(乙酰丙酮氧钒)=2.5:1:0.01、反应温度为20℃、丙酮为溶剂、反应2h条件下,α-蒎烯转化率为50.2%,龙脑烯醛的选择性达58.7%,反应6h后α-蒎烯转化率可达73.0%,主要产物龙脑烯醛和马鞭草烯酮的选择性分别为47.2%和13.2%。     

改性VPO催化剂选择性催化氧化苯乙烯合成苯甲醛

以30%H2O2为氧化剂,金属助剂改性VPO为催化剂选择性氧化苯乙烯合成苯甲醛.研究了金属助剂、反应时间、温度、溶剂、氧化剂的量等对反应的影响.结果表明,镍助剂修饰的VPO能显著提高苯甲醛选择性,在Ni-VPO催化剂用量为5%,n(苯乙烯)∶n(H2O2)=1∶2,乙腈做溶剂50℃反应6 h的最优条件下,苯乙烯转化率为80.6%,苯甲醛选择性74%.XRD、FT-IR、SEM对催化剂进行表征并提出了可能的反应机理.     

氯固相合成Ti-ZSM-5催化苯乙烯环氧化对映选择性 的研究

用TiCl~4气固相同晶取代法制得的Ti-ZSM-5作催化剂。研究了以H~2O~2为氧化剂氧化苯乙烯生成环氧苯乙烷的对映选择性,发现生成的环氧苯乙烷主要以R构型为主。考察了反应时间,反应温度,催化剂Ti-ZSM-5以及氧化剂[w(H~2O~2)=30%]的用量等反应条件对苯乙烯环氧化反应对映性的影响。结果表明,反应温度是影响环氧化反应对映选择性的重要因素,降低反应温度有利于提高对映选择性(ee),当反应温度≤40℃时,ee值可达100%;而反应时间,催化剂及氧化剂[w(H~2O~2)=30%]用量对环氧化反应的对映选择性几乎没有影响。     

氯固相合成Ti-ZSM-5催化苯乙烯环氧化对映选择性 的研究

用TiCl~4气固相同晶取代法制得的Ti-ZSM-5作催化剂。研究了以H~2O~2为氧化剂氧化苯乙烯生成环氧苯乙烷的对映选择性,发现生成的环氧苯乙烷主要以R构型为主。考察了反应时间,反应温度,催化剂Ti-ZSM-5以及氧化剂[w(H~2O~2)=30%]的用量等反应条件对苯乙烯环氧化反应对映性的影响。结果表明,反应温度是影响环氧化反应对映选择性的重要因素,降低反应温度有利于提高对映选择性(ee),当反应温度≤40℃时,ee值可达100%;而反应时间,催化剂及氧化剂[w(H~2O~2)=30%]用量对环氧化反应的对映选择性几乎没有影响。     

金属次卟啉二甲酯催化氧化苯乙烯制苯甲醛

将金属次卟啉二甲酯用作叔丁基过氧化氢（TBHP）氧化苯乙烯制苯甲醛的催化剂。 考察了催化剂、氧化剂用量、反应温度、时间、溶剂和不同金属次卟啉二甲酯[M(DPDME)]对苯乙烯转化率及苯甲醛选择性的影响,初步探索了反应机理。 结果表明,金属次卟啉二甲酯能够顺利地选择性催化氧化苯乙烯生成苯甲醛。 以0.002 mmol锰次卟啉二甲酯[ClMn(DPDME)]为催化剂,0.4 mmol TBHP为氧化剂,1 mmol苯乙烯为底物,5 mL CH3CN/H2O(体积比4∶1)为溶剂,反应温度75 ℃,常压反应20 h,苯乙烯的转化率达到98.3%,苯甲醛的选择性为92.7%。     

纳米钼钒砷杂多酸盐催化苯羟化合成苯酚的研究

过氧化氢作为一种清洁氧化剂,在苯的直接羟化的研究中受到重视。催化剂主要有含钛催化剂系列、含铁催化剂系列和含铜催化剂系列、含钒催化剂系列和其它杂原子催化剂。杂多化合物是一类酸性和氧化性较强的双功能催化剂,但由于受其低比表面积的限制,导致杂多化合物固有的高催化活性在苯的过氧化氢羟化反应中难以充分发挥。本文对所制得的4种过渡金属钼钒砷杂多酸盐纳米催化剂应用于苯的过氧化氢直接羟化合成苯酚的反应,取得了苯酚收率〉50％,选择性〉98％的结果。     

溴化四丁铵催化苯乙烯一步合成苯乙烯环状碳酸酯

以溴化季铵盐为催化剂, 通过苯乙烯的环氧化和CO2的加成反应一步直接合成出苯乙烯环状碳酸酯, 详细考察了催化剂的用量、氧化剂的种类、反应温度、反应时间和CO2压力等因素对反应主产物收率的影响. 结果表明, 以溴化四丁铵为催化剂, 于80 ℃和1 MPa CO2下反应6 h, 环状碳酸酯的收率达到38%, 这是季铵盐阳离子和亲核性阴离子协同催化的结果.     

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%.     

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.     

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.     

Copper catalyzed/mediated synthetic methodology for ebselen and related isoselenazolones

Scope of the copper catalyzed/mediated selenium-nitrogen coupling reaction has been studied for the synthesis of isoselenazolones. It is noticed that the 2-chloro, 2-bromo-, and 2-iodo-aryl amides substrates can be exploited in the selenium-nitrogen coupling reaction by employing 25-100 mol % of CuI/1,10-phenanthroline (L) and potassium carbonate as a base in DMF. Furthermore, electron rich 2-chloro-arylamides also underwent selenium-nitrogen coupling reaction to give biologically important selenium-nitrogen heterocycles. Also, copper-catalyzed selenium-nitrogen coupling reaction has been meticulously applied for the synthesis of diaryl diselenides having methoxy, amine, and amide functionality from respective aryl iodides in the presence of stoichiometric amount of succinimide as an external Se-N coupling partner.     

Knoevenagel condensation catalyzed by novel Nmm-based ionic liquids in water

A series of novel N-methyl morpholine (Nmm) based ionic liquids with 1,2-propanediol group were synthesized and used as catalysts for Knoevenagel condensation at room temperature in water. Under the effect of the catalyst, various aldehydes or aliphatic ketones could react with a wide range of activated methylene compounds well, including malononitrile, alkyl cyanoacetate, cyanoacetamide, β-diketone, barbituric acid, 2-arylacetonitrile and thiazolidinedione. Furthermore, most of the products could be separated just by filtrating and washing with water. Additionally, the catalyst is recyclable and applicable for the large-scale synthesis.     

Construction of polyheterocyclic spirotetrahydrothiophene derivatives via sulfa-Michael/aldol cascade reaction

A series of polyheterocyclic spirotetrahydrothiophene derivatives were obtained in moderate to excellent yields via a catalyst-free sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 under mild conditions. We also present the first asymmetric sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 with moderate to good enantioselectivities catalyzed by readily available chiral phase-transfer catalysts (PTCs).