质谱法研究角型二氢吡喃香豆素双酯化物酰基连接位置

研究了角型二氢吡喃香豆素双酯化物的ＥＩＭＳ，并结合Ｘ－射线单晶衍射分析，证实Ｃ－３′连接的酰氧基较容易和４′－Ｈ脱去羧酸，生成Ｍ－Ｒ１ＣＯＯＨ的碎片离子。而Ｃ－４′连接的酰氧基不能以羧酸的形式脱去，只能脱去酰氧基，生成Ｍ－Ｒ２ＣＯＯ碎片离子，故当两个酰基的质量数不同时，可实际应用ＥＩＭＳ确定酰基的连接位置。

TiO_2负载磷钨酸催化剂的制备及其催化乙二醇与硬脂酸双酯化反应研究

以二氧化钛为载体、磷钨酸为活性物质,采用浸渍法制备了二氧化钛负载磷钨酸催化剂,硬脂酸和乙二醇双酯化反应为模版,筛选出高活性的负载型催化剂.探讨了不同载体、负载量、催化剂用量及其重复使用对双酯化反应的影响.当二氧化钛负载磷钨酸的负载量为15.8%,催化剂用量为0.2%,反应温度为120℃,反应4h,产物产率可达93.5%.该负载型催化剂是一种选择性高、催化性能良好的环境友好型催化剂,而且重复使用效果好.

双酯化淀粉的特性及其在面条和儿童玩具中的应用

以玉米淀粉为原料,醋酸酐和三偏磷酸钠为酯化剂,研究了经双酯化改性后淀粉的流变学特性及其对面条、儿童玩具的质构特性的影响。结果表明,经双酯化改性后淀粉糊的透明度上升、冻融稳定性增强、热稳定性提高、抗剪切性提高。添加双酯化淀粉制作的面条硬度下降、弹性增加、咀嚼性和回复性提高,综合品质有所提高;用双酯化淀粉与聚乙烯醇(PVA)复合制备的淀粉玩具,软硬适中、弹性好、内聚性和回复性优良,综合性能得到改善。

12-羟基硬脂酸乙二醇双酯的合成研究

以12-羟基硬脂酸和乙二醇为原料,采用单因素实验法和正交实验法对12-羟基硬脂酸乙二醇双酯的合成工艺条件进行研究。结果表明优化反应条件是:12-羟基硬脂酸与乙二醇的摩尔比为2∶1.1,反应温度135℃,反应时间4 h,催化剂对甲苯磺酸用量为12-羟基硬脂酸和乙二醇总质量的0.6%,在优化条件下合成的12-羟基硬脂酸乙二醇双酯产率可达99%以上。

苯乙酸乙酯的合成方法研究

提出了通过双酯化工艺提高苯乙酸酯化生产苯乙酸乙酯产率的生产方法

First Asymmetric Synthesis of (-)Methyl 2, 2-dimethyl-3-hydroxychromanyl-6-formate

Aim To synthesize naturally occurring (-) methyl2,2-dimethyl-3-hydroxychromanyl-6-formate. Methods Sharpless' asymmetric dihydroxylation wasemployed to construct the 3-hydroxychroman. Results First asymmetric synthesis of (-) methyl 2,2-dimethyl-3-hydroxychromanyl-6-formate (1) was accomplished starting from methyl 4-hydroxy-benzoate(2), and the absolute configuration was established. Conclusion A useful method for constructingchiral 3-hydroxychroman by employing Sharpless' asymmetric dihydroxylation is achieved.

An efficient and reusable bimetallic Ni_3Fe NPs@C catalyst for selective hydrogenation of biomass-derived levulinic acid toγ-valerolactone

Bimetallic nanostructures have attracted great interest as efficient catalyst to enhance activity,selectivity and stability in catalytical conversion.Herein,we report a facile one‐pot carbothermal route to in‐situ controllable synthesize heterogeneous bimetallic Ni3Fe NPs@C nanocatalyst.The X‐ray diffraction,transmission electron microscopy,X‐ray photoelectron spectroscopy and N2 adsorption‐description results reveal that the Ni3Fe alloy nanoparticles are evenly embedded in carbon matrix.The as‐prepared Ni3Fe NPs@C catalyst shows excellent selective hydrogenation catalytic performance toward the conversion of levulinic acid(LA)toγ‐valerolactone(GVL)via both direct hydrogenation(DH)and transfer hydrogenation(TH).In DH of LA,the bimetallic catalyst achieved a 93.8%LA conversion efficiency with a 95.5%GVL selectivity and 38.2 mmol g–1 h–1 GVL productivity(under 130°C,2MPa H2 within 2 h),which are 6 and 40 times in comparison with monometallic Ni NPs@C and Fe NPs@C catalysts,respectively.In addition,the identical catalyst displayed a full conversion of LA with almost 100%GVL selectivity and 167.1 mmol g–1 h–1 GVL productivity at 180°C within 0.5 h in TH of LA.Under optimal reaction conditions,the DH and TH catalytic performance of 500‐Ni3Fe NPs@C(3:1)catalyst for converting LA to GVL is comparable to the state‐of‐the‐art noble‐based catalysts.The demonstrated capability of bimetallic catalyst design approach to introduce dual‐catalytic functionality for DH and TH reactions could be adoptable for other catalysis processes.

Solid base catalysts derived from Ca-M-Al(M = Mg, La, Ce, Y) layered double hydroxides for dimethyl carbonate synthesis by transesterification of methanol with propylene carbonate

Composite solid base catalysts derived from Ca‐M‐Al(M=Mg,La,Ce,Y)layered double hydroxides(LDH)were synthesized,characterized and applied to the transesterification of methanol with propylene carbonate.X‐ray diffraction analyses of the catalysts show that all of the catalysts were in the form of composite oxides.Compared with the Ca‐Al LDH catalyst,the specific surface areas and pore volumes of the catalysts were increased with the introduction of Mg,La or Ce.The catalytic performance of these catalysts increases in the order of Ca‐Y‐Al<Ca‐Al<Ca‐Ce‐Al<Ca‐La‐Al<Ca‐Mg‐Al,which is consistent with the total surface basic amounts of these materials and the formation of especially strong basic sites following modification with Mg and La.The Ca‐Mg‐Al catalyst shows the highest(Ca+Mg):Al atomic ratio,indicating that it likely contains more unsaturated O2?ions,providing it with the highest concentration of very strong basic sites.The recyclability of these catalysts is improved following the addition of Mg,La,Ce or Y,with the Ca‐Mg‐Al maintaining a high level of activity after ten recycling trials.X‐ray diffraction analyses of fresh and used Ca‐Mg‐Al demonstrate that this catalyst is exceptionally stable,which could be of value in practical applications related to heterogeneous catalysis.

Diester Derivatives from Chemically Modified Waste Cooking Oil as Substitute for Petroleum Based Lubricating Oils

In order to provide a new way for waste cooking oil(WCO) resource utilization, several diester derivatives were obtained from WCO through a three-step chemical modifications, viz.: transesterification, epoxidation and oxirane ring opening with carboxylic acids. The effects of the chain length of side chain groups on the viscosity, acid value, low temperature fluidity, thermo-oxidative stability, tribological properties and surface tension of diester derivatives were investigated. The results showed that increasing the chain length of side chain groups had a positive influence on the viscosity, viscosity index, acid value, pour point, friction coefficient and wear scar diameter along with a negative influence on the oxidation onset temperature, volatile loss, insoluble deposit, maximum non-seizure load and surface tension. These diester derivatives exhibited improved physicochemical and tribological properties that make themselves promising environmentally friendly biolubricant basestocks.

Spectroscopic Analysis of Structural Transformation in Biodiesel Oxidation

The oxidation behavior of three biodiesels of different origins,viz.rapeseed oil derived biodiesel,soybean oil derived biodiesel and waste oil based biodiesel,were tested on an oxidation tester.The chemical compositions of the biodiesels were characterized by gas chromatography.Thereafter,the structural transformation of fatty acid methyl ester(FAME)of the biodiesels was analyzed by an infrared spectrometer and an ultraviolet absorption spectrometer.The results demonstrated that the oxidation behavior of biodiesels of different origins was closely related to the composition and distribution of FAMEs.Higher concentration of unsaturated FAME with multi-double bonds exhibited poorer oxidation resistance.Furthermore,cis-trans isomerization transformation occurred in the unsaturated FAME molecules and conjugated double-bond produced during the oxidation process of biodiesel.Greater cis-trans variations corresponded to deeper oxidation degree.The higher the content of unsaturated FAME with multi-double bonds in a biodiesel,the more the conjugated double bonds was formed.

Fluorous Biphase System of C9F18 and Its Use in Esterification

Some apolar organic solvents is miscible with perfluorous nonene to form fluorous biphase systems.Perfluorous nonene could be used as a green solvent in equimolar esterification of carboxylic acids with alcohols without removal of water or ester formed. Perfluorous nonene made the esterification equilibrium to move right and the yields of esterification to enhance in different degrees as compared with that in the absence of perfluorous nonene. After esterification perfluorous nonene is easy to be recovered and recycled.

双活性磺酸基蔗渣木聚糖对羟基苯甲酸酯的合成及活性模拟

以蔗渣木聚糖(BX)为主要原料、氨基三磺酸钠为酯化剂,在一步酯化合成磺酸基蔗渣木聚糖酯的基础上,利用磺酸基蔗渣木聚糖酯和对羟基苯甲酸进行二步酯化反应,合成了磺酸基蔗渣木聚糖对羟基苯甲酸酯,并考察了反应条件对酯化反应的影响,通过单因素实验确定了第二步酯化反应较佳的合成工艺条件.蔗渣木聚糖酯化改性前后的样品分别用FT-IR,DG-DTG和XRD进行了表征,并对该双酯化衍生物的分子进行了优化与活性模拟.结果表明:FT-IR证明双酯化产物含有磺酸基团和对羟基苯甲酸酯基团,TG-DTG分析表明该双酯化衍生物的热稳定性提高,XRD说明发生双酯化改性后分子排列的规整性提高,结晶度增加;活性模拟实现了磺酸基蔗渣木聚糖对羟基苯甲酸酯与艾滋病毒的对接.

Direct Synthesis of Dimethyl Carbonate from CO_2 and CH_3OH Using 0.4nm Molecular Sieve Supported Cu-Ni Bimetal Catalyst

The 0.4 nm molecular sieve supported Cu-Ni bimetal catalysts for direct synthesis of dimethyl carbonate (DMC) from CO 2 and CH 3 OH were prepared and investigated. The synthesized catalysts were fully characterized by BET, XRD (X-ray diffraction), TPR (temperature programmed reduction), IR (infra-red adsorption), NH 3-TPD (temperature programmed desorption) and CO 2-TPD (temperature programmed desorption) techniques. The results showed that the surface area of catalysts decreased with increasing metal content, and the metals as well as Cu-Ni alloy co-existed on the reduced catalyst surface. There existed interaction between metal and carrier, and moreover, metal particles affected obviously the acidity and basicity of carrier. The large amount of basic sites facilitated the activation of methanol to methoxyl species and their subsequent reaction with activated carbon dioxide. The catalysts were evaluated in a continuous tubular fixed-bed micro-gaseous reactor and the catalyst with bimetal loading of 20% (by mass) had best catalytic activities. Under the conditions of 393 K, 1.1 MPa, 5 h and gas space velocity of 510 h 1 , the selectivity and yield of DMC were higher than 86.0 % and 5.0 %, respectively.

A Simplified Green Chemistry Approach to the Synthesis of Carbon-Carbon Double Bonds Via Knoevenagel Condensation Catalyzed with ZrOCl2.8H2O

A green and simplified room-temperature procedure was reported for the synthesis of carbon-carbon double bonds by Knoevenagel condensation of various aldehydes with malononitrile and ethyl cyanoacetate in the presence of catalytic amount of ZrOCl2·8H2O in aqueous media.

Manganese-catalyzed bicyclic annulations of imines and α,β-unsaturated esters via C-H activation

A manganese-catalyzed bicyclic annulation of imines with α,β-unsaturated esters via C–H activation is described, which provides an expedient access to fused β-lactams in one-step operation with high efficiency and good functional group tolerance. Of note, both ketimines and aldimines are amenable to this transformation. Mechanistic studies have identified a five-membered azamanganacycle as the key reaction intermediate.

Improvement of the physical properties of poly(methyl methacrylate) by copolymerization with N-pentafluorophenyl maleimide; zero-orientational and photoelastic birefringence polymers with high glass transition temperatures

Copolymers of N-pentafluorophenyl maleimide (PFPMI) with methyl methacrylate (MMA) were synthesized by a free radical initiator, such as AIBN. The refractive indexes of the copolymers remained nearly constant (1.4970 at 532 nm) regardless of the polymer composition. These copolymers also showed high thermal stability. The orientational and photoelastic birefringence of the copolymers obtained were measured. Since both of the orientational and photoelastic birefringences of PMMA are negative whereas poly(PFPMI) exhibits positive, thus we have obtained nearly zero orientational and photoelastic birefringence polymers when the ratios of MMA/PFPMI were 91.8/8.2 and 97.0/3.0 mol%, respectively. Based on the experimental data, the ratios of MMA/PFPMI for zero birefringence were determined to be 88.9/11.1 and 93.8/6.2 mol% for orientational and photoelastic birefringence, respectively. The Tgs of corresponding copolymers were estimated to be 128 and 122 ℃.