Cu/SiO2催化剂制备方法对其草酸二甲酯催化氢解性能的影响

以化学吸附水解法、蒸氨法和浸渍法制备了Cu/SiO2催化剂, 并用于草酸二甲酯氢解制备乙二醇的反应. 发现用化学吸附水解法制备的催化剂具有最高的催化活性和乙二醇选择性, 乙二醇得率可达92.6%. 对还原前后不同方法制备的催化剂进行表征发现, 浸渍法制备的催化剂中Cu物种不能很好地得到分散, 因此活性较差. 蒸氨法和化学吸附水解法能较好地分散Cu物种. 由于化学吸附水解法制备的催化剂的Cu0表面积较蒸氨法的大, 且Cu＋表面积相当, 故活性高于蒸氨法制备的催化剂.     

固体超强酸SO42-/SnO2-TiO2-Al2O3催化合成PEG6000双山嵛酸酯

以自制的固体超强酸SO42-/SnO2-TiO2-Al2O3催化山嵛酸与聚乙二醇6000(PEG6000)的酯化反应,合成了PEG6000双山嵛酸酯(DB6000),其结构经IR确证。较适宜的反应条件为:PEG6000 80 mmol,n(山嵛酸):n(PEG6000)=2.2:1.0,催化剂用量为总反应物质量的0.8%,氮气保护下于210℃反应6 h,酯化率高于99%。     

固体超强酸SO2-4/SnO2-TiO2-Al2O3催化合成PEG6000双山嵛酸酯

以自制的固体超强酸5O2-/SnO2-TiO2-Al2O3催化山嵛酸与聚乙二醇6000(PEG6000)的酯化反应,合成了PEG6000双山嵛酸酯(DB6000),其结构经IR确证.较适宜的反应条件为:PEG6000 80 mmol,n(山嵛酸)∶n(PEG6000) =2.2∶1.0,催化剂用量为总反应物质量的0.8％,氮气保护下于210℃反应6h,酯佗率高于99％.     

复合酶耦合酶解酸处理后玉米秸秆的研究

以玉米秸秆为研究对象,经过2%硫酸预处理后,利用果胶酶、β-葡萄糖苷酶、纤维素酶三种酶协同酶解,以提高玉米秸秆的酶解产糖量。结果表明:当酶解时间为48h,果胶酶、β-葡萄糖苷酶、纤维素酶分别为45U/mL、30U/mL、60U/mL时,葡萄糖、木糖和酶水解得率分别为67.83%、3.25%、73.65%,相比纤维素酶单一酶解的葡萄糖、木糖和酶水解得率分别提高了65.04%、20.82%、65.06%。分步糖化发酵5天后,相比单一酶解发酵乙醇含量提高了72.5%。说明利用三种酶复合处理,能明显提高酶解产糖量。研究结果为玉米秸秆转化为可发酵糖技术的研究提供重要参考。     

微波辅助DMSO/AmimCl复合溶剂预处理玉米秸秆的酶解影响

为了实现玉米秸秆纤维素的高效糖化, 设计利用微波加热辅助的离子液体1-烯丙基-3-甲基咪唑氯盐(AmimCl)/二甲基亚砜(DMSO)复合溶剂生物质预处理体系, 破坏玉米秸秆天然结构, 提高纤维素酶解效率. 研究发现, 15% (w)DMSO, 110℃, 60 min 及4 g 秸秆/100 g 复合溶剂为最适预处理条件. 在此条件下, 秸秆溶解率、提取率可分别达46.6%和22.9%; 提取物纤维素酶解率14 h 可达71.4%, 相较于天然玉米秸秆的20 h 酶解率12.5%有极大提高. 通过XRD,SEM及¹H NMR 分析发现:秸秆预处理后, 提取物纤维素晶型由Ⅰ 型变为Ⅱ 型, 残渣纤维素相对结晶度明显降低, 有利于纤维素酶解的进行, 达到了生物质预处理的目的; 预处理过程中使用的AmimCl 离子液体经简单回收再生, 结构及秸秆溶解性能未发生变化, 可循环使用. 为玉米秸秆生物质预处理提供了一个新的方案.     

水解可控功能切换型聚合刷的构筑及表面性能

采用表面受限光接枝技术在玻璃表面构筑末端酯键可水解的羧酸甜菜碱酯阳离子聚合物刷(PCBMA-1C2),通过调节氨水浓度控制羧酸甜菜碱酯末端酯键的水解程度,实现表面聚合物刷中季铵阳离子和羧酸甜菜碱两性离子基团分配比例的改变.通过X射线光电子能谱(XPS)和接触角测试表征了改性表面的化学结构和亲/疏水性能,通过蛋白质吸附和血小板黏附实验研究了玻璃表面改性前后及水解前后电荷性质对生物分子相互作用的影响.结果发现,当氨水浓度为0.1,0.2,0.3和0.4 mol/L时,聚合物刷PCBMA-1C2改性表面羧酸甜菜碱酯末端酯键的水解率分别为6%,43%,56%和~100%,随着水解程度的增大,改性表面牛血清白蛋白(BSA)的吸附量依次降低了3%,76%,93%,96%,纤维蛋白原(Fg)吸附量则依次降低了11%,45%,90%和96%;当水解率50%时,改性表面表现出优异的抗蛋白质吸附和血小板黏附性能.     

强酸型离子交换树脂催化吸附制备Valienamine

以阿卡波糖为原料制备α-糖苷酶抑制剂Valienamine,通过对比硫酸、三氟乙酸和强酸型阳离子交换树脂催化水解阿卡波糖的效果,证实强酸型阳离子交换树脂效果最好,并且在催化水解的同时,产物Valienamine生成后即被吸附在树脂上,糖类副产物水洗即可除去;在实验选择的树脂中,以Amberlyst A-15催化活性最强,阿卡波糖水解率可达95.6%,国产001×7树脂水解率虽稍有逊色,但洗脱容易;选择9种大孔吸附树脂分别对Valienamine进行吸附和解析纯化试验,其中H1020型号树脂效果最好,80%甲醇解析效果最好;采用活性炭纯化Valienamine,用量为25mg/g阿卡波穰时,纯化效果最好,本实验条件下得到的Valienamine纯度为98.26%,得率为74.3%.     

提高纤维素酶水解效率和降低水解成本

在我国可大量转化乙醇的是纤维质材料.纤维质材料转化乙醇的关键问题是纤维质转化为糖的过程,提高纤维素酶转化效率的方法有:(1)对纤维质材料进行预处理;(2)研究纤维素酶的最适作用条件;(3)纤维素酶的重复利用;(4)合理的发酵工艺等.本文分析了纤维素的结构以及纤维素酶的作用方式,总结了目前研究较多的几种纤维质材料预处理方法,及其对纤维素酶水解率的影响,并对研究纤维素酶的最适作用条件、纤维素酶的重复利用以及合理的发酵工艺进行了综述和分析.     

提高纤维素酶水解效率和降低水解成本

在我国可大量转化乙醇的是纤维质材料.纤维质材料转化乙醇的关键问题是纤维质转化为糖的过程,提高纤维素酶转化效率的方法有:(1)对纤维质材料进行预处理;(2)研究纤维素酶的最适作用条件;(3)纤维素酶的重复利用;(4)合理的发酵工艺等.本文分析了纤维素的结构以及纤维素酶的作用方式,总结了目前研究较多的几种纤维质材料预处理方法,及其对纤维素酶水解率的影响,并对研究纤维素酶的最适作用条件、纤维素酶的重复利用以及合理的发酵工艺进行了综述和分析.     

柠檬渣制取吸附Cr~(6+)水处理剂的研究

为了将柠檬渣制成绿色水处理剂,达到"以废治废"的目的,利用单因素法考查了硫酸浓度、浸泡时间、烘干温度和烘干时间等对柠檬渣吸附Cr~(6+)的影响;在单因素基础上设计了L16(45)实验,比较了改性柠檬渣与柠檬原渣的吸附性能,并利用差热分析(TG-DTA)、扫描电镜(SEM)和能谱(EDS)进行了表征。实验结果表明,改性柠檬渣制取吸附Cr~(6+)水处理剂的最优组合:硫酸浓度为10%、浸泡时间为10h、烘干时间为2.5h和烘干温度为100℃。在最优组合条件下,改性柠檬渣的吸附性能较柠檬原渣有很大的提高,对Cr~(6+)的吸附率可达95.1%。改性柠檬渣的BET比表面积越大、羧基和酚羟基的量越多,越有利于对Cr~(6+)的吸附。柠檬渣经改性后表面变疏松,主要为中孔,Cr~(6+)能被改性柠檬渣有效地吸附。     

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.     

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.     

A carbanion induced synthesis of highly congested pyrazole and imidazole containing heterocycles

An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.     

Synthesis of pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles by Curtius reaction in Morita-Baylis-Hillman derivatives

Synthesis of substituted pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles from the Morita-Baylis-Hillman derivatives of acrylates via saponification followed by Curtius reaction is described.     

正丁胺对激光染料荧光谱影响的研究

用正丁胺作为碳源,采用射频辉光放电制备碳膜,选用激光染料R6G和聚乙二醇混合液作为蒸气源,采用单源热蒸发,在蒸发室与染料同时沉积得到混合膜,用拉曼光谱和红外光谱分析了碳膜的结构和键合方式,分析表明:碳膜中存在胺基团和氢原子.混合膜的荧光谱测量结果表明,认为正丁胺对染料荧光谱的影响是因为胺基和氢原子的存在.     

Selective synthesis of 4,5-dihydroimidazo- and imidazo[1,5-a]quinoxalines via modified Pictet–Spengler reaction

An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction.     

Understanding the Diels-Alder reactivity of 1,2-azaborine analogues

The Diels-Alder reactivity of 1,2-heteroborines (H₄C₄B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed.