Fe-Al-α,α′-联吡啶催化体系催化马来酸酐与环氧丙烷开环共聚

马来酸酐与环氧丙烷开环共聚,所得聚酯具有功能团（C＝C）,可以通过接技、交联待方法改变其性能,马来酸杆与环氧化物开环共聚合成聚酯,所用催化剂通用有有机金属化合物和稀土 事物等,我们在铁系催化丁二聚合和马来酸酐与苯乙烯共聚的基础上,首次将Fe(acac)3-Al(i-Bu)3-α,α′－联吡啶催化剂用于马来酸酐与环氧化物开环共聚,发现该催化剂催化共聚反应具有时间短、收率高、共聚物交替度高等优点,并测定了共聚合反应动力学的参数。     

Fe-Al-α,α′-联吡啶催化PA与PO、 PA与ECH开环共聚

用Fe(acac)3-Al(I-Bu)3-α,α′-联吡啶(acac=乙酰丙酮)催化邻苯二甲酸酐(PA)与环氧丙烷(PO)、邻苯二甲酸酐与环氧氯丙烷(ECH)开环交替共聚 . 研究了Fe/Al、 Fe/α,α′-联吡啶摩尔比对聚合的影响; 用核磁共振技术研究了共聚物的交替度, 测得共聚物中邻苯二甲酸酐含量达46%以上. 共聚反应动力学研究表明, 共聚反应速度与单体浓度及催化剂浓度均呈一级关系; PA-PO、 PA-ECH的表观活化能分别为109.3和99.7 kJ/mol.     

乙酰丙酮钇催化环氧氯丙烷的均聚合与共聚合

用过渡金属络合催化剂聚合环氧氯丙烷能获高分子量的聚合物。稀土络合催化剂对环氧乙烷,环氧丙烷及环硫丙烷的开环聚合具有明显效果。本文选用Y(acac)_3-H_2O-Al(i-Bu)_3催化剂,考察环氧氯丙烷的均聚合及其与环氧乙烷,环氧丙烷的共聚合,并用核     

Fe(acac)3-Al(i-Bu)3-8-羟基喹啉催化体系催化丙烯酸甲酯聚合

研究了Fe(acac)3-Al(i-Bu)3-8-羟基喹啉（acac=乙酰丙酮）催化体系催化丙烯酸甲酯（MA）聚合，用凝胶渗透色谱研究了聚合物分子量和分子量分布，结果显示，分子量分布很窄，动力学研究表明，聚合反应对单体浓度呈一级关系，表观活化能为39．1KJ／mol。     

铁化合物-Al(i-Bu)3卤化物系催化剂的ESR研究

用ESR法研究了Fe(naph)2-Al(i-Bu)3-烯丙基氯和Fe(acac)3-Al(i-Bu)3-AlEt2Cl两个反应体系.以了解这类含铁催化剂的催化机理.结果表明,不管它们的起始铁化合物中的铁离子是II价还是III价,由它们和Al(i-Bu)3及卤化物反应组成的活性催化剂,其活性中心铁离子均是II价.这一结果为进一步确定铁系催化剂活性中心的结构提供了重要依据.     

Fe-Al-〆,〆′-联吡啶催化PA与PO、PA与ECH开环共聚

用 Fe(acac) 3- Al(i- Bu) 3- α,α′-联吡啶 (acac=乙酰丙酮 )催化邻苯二甲酸酐 (PA)与环氧丙烷 (PO)、邻苯二甲酸酐与环氧氯丙烷 (ECH)开环交替共聚 .研究了 Fe/Al、Fe/α,α′-联吡啶摩尔比对聚合的影响 ;用核磁共振技术研究了共聚物的交替度 ,测得共聚物中邻苯二甲酸酐含量达 46 %以上 .共聚反应动力学研究表明 ,共聚反应速度与单体浓度及催化剂浓度均呈一级关系 ;PA- PO、PA- ECH的表观活化能分别为 10 9.3和 99.7k J/mol     

乙酰丙酮铁催化丙交酯开环聚合的研究

以乙酰丙酮铁 [Fe(acac) 3]为催化剂进行D ,L 丙交酯的开环聚合及在聚乙二醇 (PEG)存在下的开环共聚 ,研究了催化剂用量、反应温度和反应时间对聚合反应的影响以及PEG用量对共聚反应的影响 ,并探讨了丙交酯开环聚合机理 .结果表明 ,Fe(acac) 3是按配位 插入机理催化丙交酯开环聚合的 ;在本文的聚合条件下 ,大部分聚合的单体转化率都达 90 %以上 ,聚合产物的粘均分子量最高可达 6 6 0 0 0 ,均显示出较好的催化性能 .在PEG存在下 ,PEG作为引发剂参入了丙交酯的开环聚合 ,D ,L 丙交酯是沿着PEG分子两端开环聚合的 ,分子链的链端结构是以羟基为端基的乳酰基结构单元 ,Fe(acac) 3有促进PEG参与聚合成酯的作用 .     

环氧化物稀土络合催化开环聚合动力学研究

用膨胀计方法研究环氧丙烷、环氧氯丙烷在稀土络合催化剂 Nd(P_(204))_3-Al(i-Bu)_3-H_2O作用下的聚合反应动力学,表明聚合反应速度对催化剂浓度及单体浓度均呈一级关系。环氧丙烷、环氧氯丙烷开环聚合反应活化能分别为61.3kJ/mol和48.9kJ/mol。在同样的聚合反应条件下,环氧氯丙烷聚合反应速度大于环氧丙烷聚合反应速度。 研究还发现,催化剂组成摩尔比Al/Nd及H_2O/Al对聚合反应速度均有一定影响;各种稀土元素络合催化剂催化活性顺序为:Nd>La>Dy>Yb>Eu;稀土络合物中配体对活性的影响为:acac>P_(204)>P_(507)>naph;烷基铝的影响为:Al(i-Bu)_3>AlEt_3。     

丁二烯聚合铁系催化剂的磁性分析

丁二烯聚合铁系催化剂FeCl_3-Phen-Al(i-Bu)_3的磁化率和紫外可见光谱测定结果表明,三氯化铁与乙酸乙酯(EA)形成高自旋络合物FeCl_3·(EA)_2;FeCl_3·(EA)_2-Al(i-Bu)_3体系显强铁磁性;Phen有稳定Fe(Ⅱ)、显著降低铁磁性的作用。     

Fe(acac)3-Al(i-Bu)3-CCl4催化马来酸酐与降冰片烯共聚

 研究了Fe(acac)3-Al(i-Bu)3-CCl4(acac=乙酰丙酮)催化体系对马来酸酐(MA)与降冰片烯(NBE)交替聚合反应的催化性能. 用元素分析、核磁共振和红外光谱研究了共聚物的结构,在单体比为1∶1时,共聚物中MA和NBE的含量分别为52.2%和47.8%. 凝胶渗透色谱结果表明共聚物分子量分布窄. 动力学研究结果表明, MA与NBE共聚对单体浓度呈一级反应,其表观活化能为74.3 kJ/mol.     

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%.     

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.     

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%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

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.