纤维素基磁性聚偕胺肟树脂的研究——溴在树脂上的吸附动力学

研究了酸式和碱式纤维素基磁性聚偕胺肟树脂(AMAO,BMAO)对溴的吸附行为.结果表明,吸附速度不但受控于粒内扩散,也受质量作用的影响.BMAO吸溴量与溴浓度有关,符合Freundlich和Langmuir等温吸附方程.溴在树脂上高的摩尔比吸附暗示着吸附后随即进行氧化还原反应,并可能发生连续再吸附.     

纤维素基磁性聚偕胺肟树脂的研究——循环吸溴中吸附与还原能力的变化

研究了酸式纤维素基磁性聚偕胺肟树脂（ＡＭＡＯ）在循环吸溴过程中吸附容量和还原能力的变化，发现原树脂的吸溴初速和溴的还原率比再生树脂高一倍以上，但第一次和第二次再生树脂的吸附速度和还原效率几乎相同，暗示着树脂吸溴后基本结构已发生了彻底的变化．树脂在循环使用时吸溴容量变化不大而溴的还原量却显著降低，表明ＡＭＡＯ作为吸溴剂有较高的实用价值．     

笼形聚偕胺肟树脂的研究──(NH_4)_2IrCl_6在碱式树脂上吸附与还原过程

超当量吸附是碱式笼形聚偕胺肟树脂（BCAO）吸附氯铱酸铵的特征之一．被吸附的氯铱酸铵与浴液中树脂的偕胺肟基的摩尔比为3．0，表明物理吸附在吸附过程中起主导作用．吸附结果是氯铱酸铵和偕胺肟基结合而成1：1络合物，并且发生了氧化还原反应，后者从扫描电镜观察得到证实。     

纤维素基磁性聚偕胺肟树脂的研究──(NH_4)_2IrCl_6在树脂上的吸附

碱式纤维素基磁性聚偕胺肟树脂（ＢＭＡＯ）吸附（ＮＨ４）２ＩｒＣｌ６是快速过程，属超当量吸附。吸附结果生成ＡＯ－Ｉｒ和ＡＯ２－Ｉｒ３络合物，随后Ｉｒ（Ⅳ）被偕胺肟基还原为Ｉｒ（０），聚集成球状晶簇附着在树脂表面。     

发给素基磁性聚偕胺肟树脂的研究：溴在树脂上的吸附动力学

研究了酸式和碱式纤维基磁性聚偕胺肟树脂对溴的吸附行为。结果表明，吸附速度不但受控于粒内扩散，也受质量作用的影响。ＢＭＡＯ吸溴量溴浓度有关，符合Ｆｒｅｕｎｄｌｉｃｈ和Ｌａｎｇｍｕｉｒ等温吸附方程。     

纤维素基磁性聚偕胺肟树脂吸附锂

研究了氯化锂浓度、树脂含量和溶液的ＰＨ对碱式纤维素基磁性聚偕胺肟树脂吸附Ｌｉ＾＋离子能力的影响。在适当条件下，每个偕胺肟基可吸附两个Ｌｉ＾＋离子。     

纤维素基磁性聚偕胺肟树脂研究：HAuCl4在树脂上的吸附与还原

研究了ＨＡｕＣｌ４在碱式纤维素基磁性聚偕胺肟树脂上的吸附动力学。吸附容量与吸附时间关系在初吸附的３０ｍｉｎ内可表示为Ｑ＝０．６４ｔ＾０．４。粒内扩散是吸附速度的控制阶段。在吸附过程中，同时发生氧化还原反应，Ａｕ（０）以不同聚集态附着在树脂表面。     

纤维素基磁性聚偕肟树脂的研究：—（NH4）2IrCl6在树脂上的咐吸

碱式纤维系基磁性聚偕胺肟树脂（ＢＭＡＯ）吸附（ＮＨ４）ＩｒＣｌ６是快速过程，属超当量吸附。吸附结果生成ＡＯ－Ｉｒ和ＡＯ２－Ｉｒ３络合物，随后Ｉｒ（Ⅳ）被偕胺肟基还原为Ｉｒ（０），聚集成球状晶簇随着在树脂表面。     

纤维素基磁性聚偕氨肟树脂吸附Mn（Ⅶ）

用酸处理的纤维素基磁性聚偕氨肟树脂（AMAO）在溶液中吸附KMnO4，发生氧化还原反应的几率在2％以下；用碱处理的树脂（BMAO）作吸附剂，KMnO4还原为Mn（OH）4的比例剧增，达到或超过10％，并且与溶液的pH有关。但是，Mn（Ⅶ）被还原为Mn（Ⅳ）的量基本上不受KMnO4起始浓度、吸附剂添加量和吸附时间变化的影响。BMAO树脂吸附KMnO4的量是树脂偕氨肟基含量的5倍以上。超当量吸附现象反映了物理吸附的本质。     

纤维素基磁性聚偕胺肟树脂的研究：树脂对氯钯酸的吸附行为

H2PdCl4在纤维素基磁性聚偕胺肟树脂上的吸附是一个复杂的过程。在生成AO－H2pDcL4络合物时伴随着外加酸的竞争吸附、物理吸附和氧化还原作用等副反应。物理扩散和化学吸附均非吸附速度的控制阶段，表现为快的吸附速度，接触5分钟时，讨论了吸附机理。     

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.     

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.     

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.     

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.     

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.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.