两性离子聚合物的制备及其对酶活性的影响*

以具有生物相容性的羧基甜菜碱甲基丙烯酸酯(CBMA)为单体、过硫酸铵为引发剂、亚硫酸钠为还原剂,采用自由基聚合工艺制备了羧基甜菜碱两性离子聚合物PCBMA,并对其进行核磁氢谱和凝胶渗透色谱表征,结果显示聚合物具有预期结构。进一步以葡萄糖氧化酶(GOD)为模型酶,分别制备了添加和未添加聚合物PCBMA的GOD溶液,在四种不同温度下探究酶的活性与时间的关系。结果表明,添加PCBMA的GOD在65℃条件下经过12h后,其活性浓度是对照样GOD 1h时活性浓度的103%;未添加PCBMA的对照样12h后GOD活性浓度仅为1h时的35%。羧基甜菜碱两性离子聚合物能够有效地维持酶的活性,并且温度越高聚合物对酶活性维持的效果越明显。     

布洛芬在阴离子交换树脂上的负载及其缓释

将布洛芬通过静电和疏水作用的共同作用负载于聚苯乙烯型大孔弱碱性阴离子交换树脂D301R和D301T上,最佳负载条件为:布洛芬悬浮于5~10%的乙醇水溶液中,加入树脂后在60℃下搅拌12h,负载量可达到0.49g/g树脂。研究了负载的布洛芬在模拟胃肠道的条件下(pH2下2h、pH 7.4下4h和pH 6.7下18h)的释放动力学,在前12h的释放接近于线性释放,释放率为58~60%。后12h的释放量较小,释放率为13~17%。如果每12h服药1次,第2次服药后的24h的累加释放率接近于线性释放。与聚苯乙烯骨架的大孔弱碱性阴离子交换树脂相比,聚甲基丙烯酸酯骨架的弱碱性阴离子交换树脂(甲基丙烯酸正丁酯/甲基丙烯酸N,N-二甲胺基乙酯/双甲基丙烯酸乙二醇酯共聚物)负载的布洛芬在相同释放条件下突释明显,表明布洛芬与苯乙烯型弱碱性阴离子交换树脂之间的π-π作用在布洛芬的缓释中起关键的作用。     

甲基丙烯酸二烷氨基乙酯的合成

采用直接酯缩合的方法,以甲基丙烯酸为原料合成了两种长链取代的甲基丙烯酸二烷氨基乙酯化合物。通过条件优化确定最佳反应条件为n(甲基丙烯酸) ：n(二取代乙醇胺) ：n(DMAP) ：n(EDCI)=1.01：1.00：0.20：1.01,在该反应条件下,室温反应12 h合成甲基丙烯酸N-十二烷基-N-甲氨基乙酯和甲基丙烯酸-N-十六烷基-N-甲氨基乙酯,产率分别为93%和91%。     

松香丙烯酸基二元单体与苯乙烯的共聚反应1

以丙烯酸松香加成物(RA)与甲基丙烯酸-2-羟乙酯的酯化物(RAH)为二元单体,采用溶液聚合法制备了苯乙烯与RAH的共聚物.通过正交实验法研究了反应条件对RAH与苯乙烯共聚反应的影响.对正交实验的结果分析得出:在反应温度为105℃下,RAH与苯乙烯的质量比为1:2,引发剂的用量为单体质量的1.5%,反应时间为8小时,单...     

TiSiW_(12)O_(40)/TiO_2催化合成磷酸三甲苯酯的研究

应用TiSiW_(12)O_(40)/TiO_2催化剂合成磷酸三甲苯酯研究结果表明，该催化 剂具有较高的催化活性。考察了催化剂用量、反应温度和反应时间对酯产率的影响 。在典型反应条件（催化剂用量为原料总量的1.0%，反应温度为100-120 ℃，反应 时间为8h）下所得磷酸三甲苯酯的产率为85.5%。该催化剂易于回收且可重复使用 ，具有良好的活性稳定性。     

溶剂热法制备板钛矿型TiO_2

采用溶剂热法,以钛酸四丁酯为钛源、草酸为络合剂,在弱碱性条件下制备了单一相板钛矿TiO_2。通过X射线衍射(XRD)、拉曼光谱、扫描电镜(SEM)、透射电镜(TEM)等测试手段对其进行了结构和形貌分析,考察了溶剂热温度和时间对产物结构、形貌及光催化活性的影响。研究结果表明,溶剂热法所得单一相板钛矿Ti O2为球形颗粒。溶剂热温度和时间对板钛矿结构的形成有重要影响,固定溶剂热时间为8 h时,板钛矿TiO_2的最低成相温度140℃;固定溶剂热温度为180℃时,合成板钛矿TiO_2所需的最短时间为2 h。光催化活性测试结果表明,在紫外光辐照60 min后,所得产物对10 mg·L~(-1)亚甲基蓝溶液的最高脱色率接近于96%。     

马来酸酐类聚羧酸盐减水剂的合成与性能研究

目前聚羧酸减水剂大多由甲基丙烯酸合成,而马来酸酐因其结构对称、活性较低等特点而合成工艺简单、易于控制。本文研究以马来酸酐、甲氧基聚乙二醇、乙烯基磺酸钠、甲基丙烯酸为原料采用先酯化再共聚的方法合成出了含有羧酸基、磺酸基、聚氧乙烯基的马来酸酐类聚羧酸减水剂。酯化反应是极其关键的一步,通过研究表明马来酸酐甲氧基聚乙二醇单酯最佳合成条件为:酸醇比为1.15:1、催化剂用量为MPEG质量的6%,、反应时间4h,反应温度为110℃;马来酸酐聚羧酸减水剂的最佳合成配比为n(MPEG-MA):n(SVS):n(MAA)=1:0.75:5。马来酸酐聚羧酸减水剂最佳掺量为0.5%,与市场上的减水剂最佳掺量时的效果相当。     

有机锡化合物催化甲基苯基碳酸酯歧化反应合成碳酸二苯酯

研究了不同配位基团的有机锡化合物对甲基苯基碳酸酯(MPC)歧化合成碳酸二苯酯(DPC)反应的催化性能.探究了电子效应和空间位阻对MPC歧化反应活性的影响,结果表明,有机锡化合物作为Lewis酸,与锡原子配位基团的吸电子效应和空间位阻影响相应催化剂的酸性从而影响其反应活性,电子效应的影响大于空间位阻的影响.氧化氢氧丁基锡[BuSnO(OH)]催化剂具有最好的催化性能,在BuSnO(OH)与MPC摩尔比为0.02,180℃及反应2.5 h条件下,MPC的转化率达到89.7%,DPC选择性为99.3%.     

两性甘蔗渣纤维素的合成及应用研究

以甘蔗渣纤维素为原料，碱化后，与3-氯-2-羟丙基三甲基氯化铵，甲基丙烯酸反应，得到两性纤维素，通过正交实验确定甘蔗渣纤维素阳离子改性的最佳工艺条件是：干纤维素1.6g,V(异丙醇）：V（40%NaOH):V(CHPTMA)=60:1.2:4.5，反应时间3.5h，反应温度45℃。甘蔗渣纤维素阴离子改性的最佳工艺条件是；阳离子改性纤维素3.0g，催化剂n(Fe^2 ):n(H2O2)=1:50,反应温度60℃，反应时间2h，甲基丙烯酸用量为17.2ml。改性后的产品对酸性黄染料，阳离子翠兰染料交换吸附能力比活性炭提高了33.2%和19.7%,对Pb^2 ,Zn^2 ,Cu^2 ,Cr2O7^2-的交换吸附能力比活性炭平均提高了7.4倍，对染料交换吸附速率比活性炭提高了约3.5倍，且产品再生容易，性能稳定。     

超临界CO2中丙烯酸含氟酯疏水改性聚丙烯酸的合成

研究了在超临界二氧化碳条件下 ,丙烯酸 1,1 二氢全氟辛酯 (FOA)对聚丙烯酸疏水改性的共聚反应 .发现与通常聚合方法相比含氟丙烯酸酯的产率得到提高 ;反应时间从 2 4h缩短到 4h ;所得产物的后处理也更容易 .同时发现温度对反应有影响 ,含氟酯单体在低温 (T <5 5 0℃ )时活性高于丙烯酸单体 ,在高温 (T >6 0 0℃ )时丙烯酸活性提高较大 .而共聚物水溶液粘度随pH值变化先上升后下降 ,在pH =5 0出现峰值 ,显示其中有分子间缔合存在 .与改性聚丙烯酰胺不同 ,改性聚丙烯酸水溶液粘度随FOA含量的增加而单调上升 ,也证明了分子间缔合的存在     

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.     

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).     

Suzuki-Miyaura reactions of the soluble guanylate cyclase inhibitor NS2028: a non-product specific route to C-8 substituted analogues

Both soluble guanylate cyclase (sGC) inhibitors ODQ 1 and NS2028 2 are synthesized via improved protocols. In the former case treating 3,4-dihydroquinoxalin-2(1H)-one oxime 8, which can be prepared in two steps from 1,2-benzenediamine, with 1,1′-carbonyldiimidazole (CDI) gives the dihydro-ODQ 10 that in the presence of KMnO₄ oxidises to give ODQ 1 in an overall yield of 46% starting from 1,2-benzenediamine. In the latter case, the synthesis affords NS2028 2 from 2-amino-4-bromophenol 3 in three steps with an overall yield of 85% and avoids the need for chromatography. Furthermore, Suzuki-Miyaura reaction conditions are described that enable the preparation of 8-aryl and 8-heteroaryl derivatives of NS2028 directly from NS2028 2. Finally, demethylation of the 8-(methoxyphenyl) substituted analogues afforded the 8-(hydroxyphenyl) derivatives 40-42. All new products are fully characterised.