Single-step synthesis and stabilization of metal nanoparticles in aqueous pluronic block copolymer solutions at ambient temperature

A single-step synthesis of gold nanoparticles with an average diameter of approximately 10 nm from hydrogen tetrachloroaureate(III) hydrate (HAuCl4.3H2O) has been achieved in air-saturated aqueous solutions that contain poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) block copolymers but not any other reducing agent. These amphiphilic block copolymers act as both reductants and colloidal stabilizers and prove very efficient in both functions. The formation of gold nanoparticles is controlled by the overall molecular weight and relative block length of the block copolymer. The synthesis procedure reported here is environmentally benign and economic, as it involves the minimum possible number of components: it uses water as the solvent, it uses commercially available polymers, it proceeds fast to completion, and it results in a "ready-to-use" product.     

Transesterification of Ethylene Carbonate with Dimethyl Terephthalate over Various Metal Acetate Catalysts

IntroductionDimethyl carbonate(DMC) is known to be a novelbuilding block in organic synthesis. As an environmen-tally benign compound and a unique intermediate,DMC has attracted much attention[1,2]. Among the va-rious methods for synthesizing DMC, the tra…     

PEG-SO3H as a new, highly efficient and homogeneous polymeric catalyst for the synthesis of bis(indolyl)methanes and 4,4��-(arylmethylene)-bis(3-methyl-1-phenyl-1Hpyrazol-5-ol)s in water

In this work, a green, simple and highly efficient procedure for the synthesis of bis(indolyl)methanes and 4,4??- (arylmethylene)-bis(3-methyl-1-phenyl-1H-pyrazol-5-ol)s [as an important class of bis(pyrazolyl)methanes] is described. The condensation of indoles or 1-phenyl-3-methylpyrazol-5-one with carbonyl compounds catalyzed by poly(ethylene glycol)-bound sulfonic acid (PEG-SO₃H) in water affords the title compounds in high yields and relatively short reaction times.     

碳酸乙烯酯选择加氢合成甲醇与乙二醇高效稳定Cu/SiO2催化剂研究

CO2作为重要的碳氧资源, 具有来源丰富、价格低廉、安全等突出优点. 近年来, 由于蕴含的巨大利用潜力,CO2间接利用制备基础化学品、能源燃料对于可持续制备大宗化工品中具有重要研究意义, 日益受到研究者和工业界的广泛重视.甲醇与乙二醇是化学工业中的两种重要大宗原料. 甲醇不仅是重要的有机化工原料、清洁环保的液体燃料, 同时也是氢气和能量储存的良好载体. 乙二醇作为一种重要的有机化工原料, 在聚酯等领域具有广泛应用.CO2经碳酸乙烯酯氢解制备甲醇/乙二醇是典型的原子经济反应, 对资源、能源和环境的可持续发展具有重要意义. 需要指出的是,CO2与环氧乙烷环加成制备碳酸乙烯酯已具备成熟的工业化技术. 因此, 该路线研究重点在于发展碳酸乙烯酯选择加氢联产甲醇和乙二醇高效稳定的催化体系. 近年来, 铜基多相催化剂催化碳酸乙烯酯加氢联产甲醇乙二醇得到了广泛重视. 由于铜基催化剂存在活性较低、高温易失活等问题, 开发高效且具有良好稳定性的铜基催化剂是目前碳酸乙烯酯加氢研究重点.本文针对碳酸乙烯酯选择氢解合成甲醇乙二醇新型铜基催化体系构建和构效关系研究, 采用硅溶胶蒸氨法制备高分散 Cu/SiO2过程中引入多羟基β-环糊精修饰催化剂前驱体的合成策略, 并通过惰性气体中煅烧后的积碳有效抑制活性铜物种的团聚, 获得了β-环糊精改性的 Cu/SiO2催化剂. 通过 N2吸脱附、XRD、N2O 滴定、H2-TPR、TEM 和 XPS 等系统表征,发现β-环糊精可有效调控催化剂结构和表面不同价态活性铜物种分布. 碳酸乙烯酯加氢性能评价结果表明引入适量β-环糊精的 5β-25%Cu/SiO2具有较优催化活性, 乙二醇选择性 98.8% 和甲醇选择性 71.6%, 且相应的催化活性可达 1178 mgEC gcat-1h-1. 高活性的原因很可能归因于不同价态 Cu0与 Cu+物种协同催化作用及适宜的 Cu+/(Cu0+Cu+) 比例. 结合密度泛函理论模拟计算, 我们提出了 Cu0促进氢气解离、Cu+吸附活化碳酸乙烯酯分子中酯羰基的反应机理. 催化剂重复使用和表征结果表明, 5β-25%Cu/SiO2具有良好的稳定性, 使用前后铜粒子大小和铜物种分布几乎未发生明显变化. 本文为解决铜基催化剂高温易烧结等难题提供了简单有效的活性铜物种稳定化方法, 并为CO2经碳酸乙烯酯绿色合成甲醇、乙二醇高效稳定铜基催化新体系的构筑提供了有益借鉴.     

Synthesis of penta-p-phenylenes with oligo(ethylene glycol) side chains

We report an efficient synthesis of a series of penta-p-phenylene derivatives with four side chains of various lengths, including deca(ethylene glycol) groups. The key feature of the synthesis is that the side chains are efficiently introduced in the last step, facilitating optimization of the side chains for different applications. Raman spectroscopy study indicates a similarly high rigidity for all these compounds, even those with long oligo(ethylene glycol) side chains. The deca(ethylene glycol)-substituted penta-p-phenylene derivatives are versatile building blocks for construction of nanometric, tripod-shaped adsorbates for biological applications.     

New 8-amino-BODIPY derivatives: surpassing laser dyes at blue-edge wavelengths

The development of highly efficient and stable blue‐emitting dyes to overcome some of the most important shortcomings of available chromophores is of great technological importance for modern optical, analytical, electronic, and biological applications. Here, we report the design, synthesis and characterization of new tailor‐made BODIPY dyes with efficient absorption and emission in the blue spectral region. The major challenge is the effective management of the electron‐donor strength of the substitution pattern, in order to modulate the emission of these novel dyes over a wide spectral range (430–500 nm). A direct relationship between the electron‐donor character of the substituent and the extension of the spectral hypsochromic shift is seen through the energy increase of the LUMO state. However, when the electron‐donor character of the substituent is high enough, an intramolecular charge‐transfer process appears to decrease the fluorescence ability of these dyes, especially in polar media. Some of the reported novel BODIPY dyes provide very high fluorescence quantum yields, close to unity, and large Stokes shifts, leading to highly efficient tunable dye lasers in the blue part of the spectrum; this so far remains an unexploited region with BODIPYs. In fact, under demanding transversal pumping conditions, the new dyes lase with unexpectedly high lasing efficiencies of up to 63 %, and also show high photostabilities, outperforming the laser action of other dyes considered as benchmarks in the same spectral region. Considering the easy synthetic protocol and the wide variety of possible substituents, we are confident that this strategy could be successfully extended for the development of efficient blue‐edge emitting materials and devices, impelling biophotonic and optoelectronic applications.     

Efficient Synthesis of 2‐Aminothiazoles and Fanetizole in Liquid PEG‐400 at Ambient Conditions

A simple and practical procedure for the synthesis of 2‐aminothiazoles from α‐tosyloxyketones and thioureas is described using PEG‐400[poly(ethylene glycol‐400)] at ambient conditions. The developed protocol is successfully applied for the preparation of an anti‐inflammatory drug, Fanetizole.     

A novel simplified synthesis of acivicin

This report describes an efficient synthesis of the natural isomer of acivicin, which is the only one provided with a noteworthy biological activity. The present procedure allowed the synthesis of (+)-1 in just five steps with a 34% overall yield. Due to the easy separation of the two diastereomers and to the availability of the starting material at low cost, the present procedure can be scaled-up to gram quantities.     

Synthesis and NMR Characterization of Monomethoxypoly(Ethylene Glycol) Aldehydes from Monomethoxypoly(Ethylene Glycol) Tosylates

A procedure for the synthesis of monomethoxypoly(ethylene glycol) aldehydes from monomethoxypoly(ethylene glycol) tosylates is described. The tosylates are converted to aldehydes in high yield via treatment with disodium hydrogen phosphate and DMSO; minimal oligomeric by-products are formed.     

A One‐pot,Efficient Synthesis of Polyfunctionalized Pyrido[2,3‐d]pyrimidines and Uncyclized Adducts by Aldehydes, 1,3‐Dicarbonyl Compounds,and 6‐Aminouracils

A one‐pot, efficient protocol for the synthesis of polyfunctionalized pyrido[2,3‐d]pyrimidines and uncyclized adducts by 6‐aminouracils in poly(ethylene glycol) 200/H₂O or AcOH was described. An interesting family of pyrido[2,3‐d]pyrimidines and uncyclized adducts bearing fused pharmacological active units are prepared. The reaction is free of toxic solvents and catalysts, has simple workup procedure, and has high atom economy, making it more environmentally friendly and suitable for large‐scale operations.     

BLUE LIGHT-EMITTING COIL-ROD-COIL BLOCK OLIGOMERS WITH RIGID p-HEXAPHENYL AS CHROMOPHORE

The synthesis and characterization of coil-rod-coil triblock oligomers, poly（ethylene oxide）-b-p-hexaphenyl-b- poly（ethylene oxide）, are described. The number of repeating ethylene oxide units in each flexible block are 3 （EO3-PHP- EO3）, 8 （EOs-PHP-EO8）, 13 （EO13-PHP-EO13）, and 17 （EO17-PHP-EO17）, respectively. The structures of these oligomers are confirmed by ^1H-NMR, 13C-NMR, EA, and MALDI-TOF mass spectrometry. The introduction of soluble poly（ethylene oxide） coils to the rigid p-hexaphenyl segment significantly improves the solubility of the oligomers, so they can form smooth thin films by spin-coating from their solutions. The oligomers are quite thermally stable and have 1% weight loss temperatures at above 340℃ under nitrogen. They can emit strong blue light in both solution and film state, and have fluorescence quantum yields of about 40% in chloroform. They are expected to have potential applications in optoelectronic devices.     

Exceptionally strong multiphoton-excited blue photoluminescence and lasing from ladder-type oligo(p-phenylene)s

We report the synthesis and investigation of multiphoton absorption properties of a novel series of diphenylamino-end-capped ladder-type oligo(p-phenylene)s which exhibit greatly enhanced and efficient multiphoton (from two- to five-photon) upconverted blue photoluminescence with which the record-high intrinsic three-photon absorption cross-section of 4.56 × 10(-76) cm(6) s(2) in the femtosecond regime has been obtained. Exceptionally efficient two- to five-photon-excited lasing in the blue region has also been demonstrated in which the highest two-photon-excited lasing efficiency of 0.34% has been achieved.     

An Efficient Synthesis for Some New Heterocyclic Compound‐fused Oxindole Derivatives

An efficient and rapid procedure for the synthesis of novel oxindole derivatives is described. The process employs a condensation reaction of 3‐(bis(methyl thio)methylene)indolin‐2‐one and dinucleophiles such as 1,2‐phenylene diamine, propylene diamine, 2‐aminoethanol, ethylene‐1,2‐dithiol, 2‐mercaptoethanol, (1S,2S)‐cyclohexane‐1,2‐diamine, 2‐aminoethanthiol, 2,3‐diaminomaleonitrile, 2‐aminobenzenethiol, (3,4‐diaminophenyl)(phenyl)methanone, and ethane‐1,2‐diole in the presence of triethylamine under solvent‐free conditions at 60°C.     

低压下碱金属碳酸盐催化一步法合成碳酸二甲酯

报道了低压下碱金属碳酸盐催化环氧化物、CO2和甲醇一步合成碳酸二甲酯(DMC)的方法,系统考察了反应条件对一步合成DMC的影响规律.在最优反应条件下(初始压力0.5 MPa,反应温度120°C,碳酸钠7.5 mol%),以环氧乙烷为起始剂的DMC收率达到63.5%.提出了碱金属碳酸盐催化一步法合成DMC的可能反应机理.     

Dimethyl carbonate synthesis catalyzed by DABCO-derived basic ionic liquids via transesterification of ethylene carbonate with methanol

Easily prepared DABCO-derived (1,4-diazobicyclo[2.2.2]octane) basic ionic liquids were developed for an efficient synthesis of dimethyl carbonate (DMC) via the transesterification of ethylene carbonate (EC) with methanol. 1-Butyl-4-azo-1-azoniabicyclo[2.2.2]octane hydroxide ([C₄DABCO]OH) exhibited high catalytic activity and 81% DMC yield together with 90% EC conversion was obtained under mild reaction conditions. Notably, the catalyst could be recycled for four times without loss of catalytic activity. Moreover, a possible mechanism was also discussed.     

An efficient total synthesis of (+)-heliannuol D

An efficient total synthesis of (+)-heliannuol D was accomplished in 14 steps and in 12% overall yield by employing a diastereoselective conjugate addition reaction to create a tertiary benzylic stereogenic center and simple assembly of the functionalized oxepane framework by an efficient one-pot transformation procedure as the key steps.     

CeCl3·7H2O: a highly efficient catalyst for the synthesis of 1-substituted-octahydro-[1,3,2]diazaphospholo[1,5-a]pyridine-1-oxide

An efficient and simple protocol is reported for the synthesis of a new class of 1-substituted-octahydro-[1,3,2]diazaphospholo[1,5-a]pyridine-1-oxides in good to excellent yield (88–95%) via Michaelis–Arbuzov rearrangement. Condensation of diamido phosphite with various halides at 60 °C using CeCl₃·7H₂O as a highly efficient catalyst afforded the products within a short period of reaction time. This procedure is mild, efficient, and non-toxic and stability of the catalyst is the merit of this process. Therefore, this protocol being environmentally benign and efficient, serves as an alternative procedure for the preparation of the title compounds.     

A Rapid and Efficient Biginelli Reaction Catalyzed by Zinc Triflate

An efficient and practiacal procedure for the synthesis of dihydropyrimidinones from aldehydes,1,3-dicarbonyl compounds and urea under solvent-free reaction condition using zinc triflate as a catalyst is described.In comparison with the classical Biginelli reaction,the yields for this new procedure increased from 20%-50% to 75%-98% while the reaction time was significantly shortened from 18h to 20min.     

Asymmetric synthesis of Wieland-Miescher and Hajos-Parrish ketones catalyzed by an amino-acid-derived chiral primary amine

This paper describes a simple chiral primary amine-catalyzed highly efficient and practical protocol for the synthesis of both Wieland-Miescher ketone and Hajos-Parrish ketone as well as their analogues. The reaction can be conducted in gram scale with 1% mol catalyst loading producing high enantioselectivity (up to 96% ee) and excellent yields (up to 98%). This procedure represents one of the most efficient methods for the synthesis of these versatile chiral building blocks.     

Asymmetric reductive acylation of aromatic ketoximes by enzyme-metal cocatalysis

We have developed an efficient procedure for the asymmetric synthesis of chiral amides from ketoximes. This one-pot procedure employs two different types of catalysts, Pd nanocatalyst and lipase, for three consecutive transformations including hydrogenation, racemization, and acylation. Eight ketoximes have been efficiently transformed to the corresponding amides in good yields (83-92%) and high enantiomeric excesses (93-98%).