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。     

无水二氯化镍催化下醋酸烯丙酯与亚磷酸二酯的反应

利用Pd(O)催化下R~2R~3P(O)H(R~2,R~3=烷基、芳基、烷氧基)与芳基溴,烯基溴以及丁二烯反应合成芳基、烯基和烯丙基膦酸酯近年来有较多报道,但后者产率仅为10%。Fiaud曾报道了二苯基膦锂和醋酸烯丙酯的反应,但烯丙基膦化合物产率低于15%。我们曾发现醋酸烯丙酯在O,N-二(三甲硅基)乙酰胺(BSA)存在下,用Ni(cod)_3为催化剂与亚磷酸二酯反应,高产率地得到了烯丙基膦酸酯,而Pd(PPh_3)_4不能催化这个反应。我们认为反应的关键是亚磷酸二酯首先与BSA反应生成O,O-二烷基-O-三甲硅基亚磷酸酯     

β-环糊精/聚(DL-丙交酯)接枝共聚物的合成与表征

以β-环糊精(β-CD)为接枝骨架、DL-丙交酯(DLLA)为接枝单体,三乙胺为催化剂,合成了β-环糊精/聚(DL-丙交酯)接枝共聚物(PCDLA).利用IR、1H-NMR、DSC、WXRD和GPC等方法对接枝共聚物的结构进行了表征,测定了共聚物的分子量,并研究了反应投料比对单体转化率(C%)、接枝率(G%)和接枝效率(GE%)的影响.结果表明,在三乙胺催化下,DL-丙交酯与β-环糊精能够发生聚合反应得到接枝共聚物,当DL-丙交酯与β-环糊精结构单元的摩尔比为30∶1,反应时间为10h时,接枝反应的接枝率(G%)和接枝效率(GE%)可分别达到182·9%和21·4%.随着接枝共聚物中β-环糊精含量的增加,共聚物的亲水性得到了改善.     

乙炔在钕化合物-三烷基铝-第三组分体系中的聚合规律

本文研究了不同钕化合物Nd(P_204)_3,Nd(P_507)_3,Nd(NO_3)_3·3P_350,Nd(BA)_3·3H_2O,Nd(acac)_3·3H_2O与三烷基铝,给电子化合物组成络合催化剂使乙炔聚合的规律。酸性膦酸酯钕盐Nd(P_507)_3体系具有最高的催化活性,所制得的聚乙炔膜的顺式结构含量可达97％以上。     

高分子量立构复合结晶的三枝化PPO-PDLA-PLLA嵌段共聚物

以三枝化低不饱和度聚环氧丙烷(PPO)引发D-丙交酯(D-LA)逐步开环聚合, 合成了三枝化聚环氧丙烷-聚右旋乳酸(PPO-PDLA)共聚物. 用辛酸亚锡Sn(Oct)₂与PPO-PDLA端羟基反应进行Sn(Oct)封端, 制备了三枝化PPO-PDLA-Sn(Oct)预聚物. 再于130 ℃下, 以其作为大分子引发剂与L-丙交酯(L-LA)开环聚合, 合成了分子量>10⁵的三枝化PPO-PDLA-PLLA嵌段共聚物. 活性端基的引入, 降低了聚合反应温度, 从而降低了聚合中的酯交换或热降解反应发生的概率. 实现了高分子量PPO-PDLA-PLLA嵌段共聚物的合成. 结构测试结果表明, 合成的嵌段共聚物具有分子结构易控及立构规整度高等特点. 在结晶-熔融-再结晶重复热处理下, 三枝化PPO-PDLA-PLLA嵌段共聚物仅发生立构复合聚乳酸结晶, 且结晶能力稳定.     

用可溶性催化剂合成顺式聚丁二烯的研究——Ⅱ.用钴化合物-烷基铝作催化剂

用各种钴化合物与烷基铝组成催化体系聚合丁二烯,研究其催化活性以及对高聚物链结构的影响,试验结果表明: 1.卤化钴呲啶络合物,有机酸钴盐呲啶络合物、乙酰基丙酮合钴等外轨型钴络合物均能与(i-C_4H_9)_2AlCl,(C_2H_5)_2AlCl,(C_2H_5)_2AlBr组成高活性催化体系,聚合所得到的高聚物的链结构,顺式-1,4含量大于92％,但都不能与(C_2H_5)_2AlI组成定向催化剂。 2.用内轨型的钴络合物与(i-C_4H_9)_2AlCl,(C_2H_5)_2AlCl,(C_2H_5)_2AlBr,组合为催化剂时,对高聚物的链结构没有影响,但其活性比外轨型钴络合物差得多。 3.当一卤代二烷基铝上卤素改变时,所得高聚物平均分子量的大小变化的顺序是Cl>Br>I。 4.在适当的水量存在下,(i-C_4H_9)_3Al或C_2H_5AlCl_2始能与CoCl_2·4C_5H_5N组成高活性的定向催化剂。     

Y(NO_3)_3-H_2O二元体系的研究

Y(NO_3)_3-H_2O二元体系属转熔型,它的平衡固相分别为Y(NO_3)_3·6H_2O、Y(NO_3)·5H_2O和Y(NO_3)_3·4H_2O。在Y(NO_3)_3·6H_2O相区内,Y(NO_3)_3·5H_2O的介稳现象是明显的。过饱和硝酸钇溶液在室温下结晶,常得到Y(NO_3)_3·5H_2O,而不是Y(NO_3)_3·6H_2O。本文认为,P.D.F.衍射卡所载Y(NO_3)_3·6H_2O的x-衍射数据可能是Y(NO_3)_3·5H_2O的数据。     

用钛系载体高效催化剂进行乙烯-丙烯-1-丁烯三元共聚合的研究 Ⅰ.聚合条件对共聚合反应的影响

用多组份改性钛系载体催化剂TiCl_4,Ti(OBu)_4/MgCl_2/Ethylbenzeate(EB)/φ_2SiCl_2/AlEt_3进行了乙烯-丙烯-1-丁烯三元共聚合的研究。考察了单体进料比、聚合温度,烷基铝浓度和催化剂浓度等条件对共聚合的影响。发现本催化剂对乙丙丁三元共聚合有极高的催化效率,聚合1h达8.6×10~4g共聚物/g-Ti。共聚合速率衰减符合动力学方程:R_s=R_s+(R_0—R_s)_e~(βs)。     

固相配位化学反应研究 ⅩⅩⅩⅩⅩⅢ.一步法室温(准室温)固相化学反应合成8-羟基喹啉的Co(Ⅱ)、Ni(Ⅱ)、Cu(Ⅱ)、Zn(Ⅱ)配合物

本文研究了Go(OAc)_2·4H_2O、Ni(OAc)_2·4H_2O、Cu(OAC)_2·H_2O、Zn(OAc)_2·2H_2O与8-羟基喹啉在室温(准室温≤40℃)条件下的固-固相化学反应.讨论了反应物结构对固相反应的影响.通过固相反应一步合成了相应的配合物Co(oxin)_2·2H_2O、Ni(oxin)_2·2H_2O、Gu(oxin)_2、Zn(oxin)_2·H_2O.经失重测定,元素析,IR,XRD,DTA测定,确定了固相产物的组成.与液相合成方法比较,固相反应合成配合物不用溶剂,产率较高等优点.     

顺铂与DNA结合方式——N_7、N_1链内交联模型化合物的合成和表征

以摩尔比为1:1的[Pt(NH_3)_2(H_2O)_2]·(NO_3)_2与鸟苷反应,经过重结晶,得到了1:1的纯化合物,通过摩尔电导、数均分子量、元素分析测定、~(13)CNMR、紫外光谱的表征,确定化合物为[{Pt(NH_3)2}_8(GuOH_(-1))_7(OH)_2]·(NO_3)_7·8H_2O。     

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.     

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.     

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.     

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.     

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.