丙烯酰胺的oxa-Michael加成:β-烷氧基丙酰胺的合成

本文利用醇与丙烯酰胺的oxa-Michael加成,合成了一系列β-烷氧基丙酰胺类化合物。通过NMR、HRMS表征了产物的结构。考察了催化剂、反应温度、原料配比对反应的影响。在40℃下,5(mol)%的活化碳酸钾能催化伯醇与丙烯酰胺发生oxa-Michael加成,仲醇的反应活性较低,叔醇及苯酚几乎不反应。温度升高及强碱会导致丙烯酰胺自身aza-Michael加成反应形成二聚体。醇与丙烯酰胺可以在等官能团比的无溶剂条件下反应。分子内的氢键有利于提高仲羟基的反应活性。     

Tetraphenylporphyrins monosubstituted with glycerol derivative units in the phenyl rings. Synthesis and characterization

Summary The synthesis and spectroscopic characterization of a series ofmeso-tetraphenyl substituted porphyrins appended with glycerol, diacetylglycerol, or isopropylideneglycerol units inortho,meta, orpara position of the phenylene ring is described.

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Synthese und Charakterisierung von an den Phenylresten mit Glycerinderivaten monosubstituierten Tetraphenylporphyrinen

Zusammenfassung Synthese und spektroskopische Charakterisierung einer Reihe von an den Phenylringen inortho-,meta- oderpara-Position mit Glycerin, Diacetylglycerin oder Isopropylidenglycerin substituiertenmeso-tetraphenylsubstituierten Porphyrinen wird beschrieben.

     

Multiporous Carbon Encapsulated Ni Nanoparticles Promoting Glycerol Valorisation towards Hydrogenation against Rearrangement†

A dual‐templating method was used to synthesize a series of hierarchical carbon supports containing different proportions of spherical macropores (ca. 200 nm in diameter) and mesoporous channels (ca. 4 nm in diameter). These and some other conventional carbon materials were subsequently impregnated with Ni and tested for the conversion of glycerol. The hierarchical catalysts exhibited a significantly higher conversion (96%) and selectivity (77%) to 1,2‐propanediol, and the specificity selectivity coefficient (6.1) towards 1,2‐propanediol against lactic acid was three times higher than that observed over a conventional Ni/C_micro catalyst (2.1). The enhanced performance of these materials, compared with the Ni nanoparticles supported on conventional carbon supports, was attributed to their high surface areas (> 1110 m²?g^?1) and large pore volumes (ca. 0.4 cm³?g^?1) permitting greater accessibility of substrate and/or intermediates to Ni active sites. Given that the concentration of accessible Ni sites in these materials is higher, a competitive benzilic‐acid‐rearrangement reaction to produce lactic acid was suppressed, leading to an enhanced hydrogenation selectivity to 1,2‐propanediol. This study evidences the potential benefits, which can be established from utilizing hierarchical support materials in the valorization of biomass.     

Structural characteristics of some soluble and insoluble β-cyclodextrin polymers

Several β-cyclodextrin polymers (βCDP) have been obtained by cross-linking β-cyclodextrin (βCD) with the reagent epichlorohydrin (EP). It is expected that these polymers are capable of retaining different organic molecules by adsorbing them on its network and also by forming inclusion complexes with βCDs. In this work, two soluble polymers containing 39% and 48% βCD and other insoluble ones with 65% and 74% βCD have been studied. The total amount of CD in the polymers could not be available for complexation. This parameter has been calculated by means of the decrease of colour intensity of phenolphthalein solutions when different amounts of βCDP were added. The insoluble polymer with 74% βCD appears to possess less CD available than that with 65% βCD, probably due to the higher cross-linking degree of the former. On the other hand, a higher availability of CD is found for the soluble polymer which contains 48% βCD. Moreover, the amount of glycerol monoether groups formed as a side effect during the cross-linking process has been determined and related to the epichlorohydrin content, structure and swelling properties of the polymers. It is concluded that, varying the synthesis conditions, it is possible to induce structural modifications in the hydrogel networks which can improve their practical applications.     

Synthesis of Floridoside

Floridoside (2-O-glycerol-α-D-galactopyranoside) is a natural glycerol glycoside found in red algae and is believed to play important roles in carbon storage, transport, and assimilation and in the regulation of osmotic balance. We describe here a rapid, high-yield, and high-stereoselectivity synthesis of floridoside in which the key step involves the 1,2-cis O-glycosylation of 1,3-dibenzylglycerol with ethyl 2,3,4,6-tetra-O-benzyl-1-thio-β-D-galactopyranoside using iodonium dicollidine perchlorate (IDCP) or N-iodosuccinimide/trimethylsilyl triflate (NIS/TMSOTf) as promoters.     

Sequential injection analyzer for glycerol monitoring in yeast cultivation medium

A smart and versatile flow system for the at-line monitoring of glycerol based on sequential injection analysis is proposed. Formaldehyde, generated by oxidation of glycerol with sodium periodate, is transformed into 2,4-diacetyl-1,4-dihydrolutidine applying the Hantzsch condensation reaction with acetylacetone and ammonium. Dual-wavelength detection was carried out to minimize the contribution of the schlieren effect using a single blue LED. In-line sample dilution is accomplished applying the concept of zone-penetration and a new concept of sample splitting. Under optimized physical and chemical variables, regression curves over two dynamic working ranges of 0.1-4 and 1-40 g l⁻¹ were attained. The injection throughputs were 14 and 12 h⁻¹, respectively. Applying on-line data evaluation and conditional inquiries, the smart and independent selection of the adequate analytical procedure for the required working range was accomplished. The system was successfully applied to the at-line monitoring of glycerol in a continuous, cell-free medium flow from a yeast cultivation process during batch and fed-batch phase with glycerol as the only carbon source.     

Determination of esters in glycerol phase after transesterification of vegetable oil

In biodiesel production, glycerol is formed as a side product and it is contained in the glycerol phase. This phase contains (besides glycerol): water, soaps, alcohol, traces of catalyst and glycerides and the remaining esters. In this paper, a new method for the determination of esters in the glycerol phase is introduced. The determination enables the minimization of the losses of biodiesel within the production process. It is based on the gradient RP-LC method (water and acetonitrile) with refractometric detection. The analysis is easy and the samples do not need any treatment (only dilution by water) and has a low detection limit. The results of this method were compared with the results of two other published methods: isocratic HPLC and GC. The disadvantage of these two methods is that they need extensive treatment of the sample, which takes many hours, and they are able to determine only the sum of esters. The new method is reliable, much faster and able to differentiate esters of almost each higher fatty acid (e.g. linoleic, linolenic, strearic alkyl ester) in the glycerol phase.     

Vapor–liquid equilibrium of the (water + ethanol + glycerol) system: Experimental and modelling data at normal pressure

In this work, vapor-liquid equilibrium data of the ethanol–water–glycerol system were measured in an Othmer-type ebulliometer at normal pressure. The choice for this system was due to the importance of the ethanol–water separation. The samples analyses were done in a digital densimeter, and the methodology was previously validated with data available in the literature. Since the mean relative deviation was less than 5% in temperature and vapor composition, new data from mixtures of ethanol–water–glycerol were obtained. The experiments showed that glycerol is a promising solvent to ethanol dehydration since it eliminates the azeotrope and promotes the production of anhydrous ethanol. A thermodynamic model for this system was developed using the NRTL model to describe the non-ideality of the liquid phase. The modeling results were compared with experimental data and the deviations were lower than 7%. In this way, the model developed in this work can be used for simulation of ethanol dehydration.     

液滴在超疏水植物叶面的沉积：实验和分子动力学模拟

农药液滴在靶标植物叶面的动态沉积对于提高农药利用率具有重要的意义,特别是在超疏水植物叶面的动态沉积。在本文中,我们利用生物基表面活性剂和甘油之间的氢键作用来增强液滴在超疏水植物叶面的有效沉积。在较低浓度的山梨醇-烷基胺表面活性剂溶液中,添加0.001%的甘油,可有效抑制液滴在不同超疏水/疏水植物叶片表面的弹跳和飞溅行为。结果表明,甘油的加入并没有显著改变山梨醇-烷基胺表面活性剂溶液的表面张力、粘度和聚集体的形态。核磁共振波谱(DOSY)显示,甘油加速了山梨醇-烷基胺表面活性剂分子的扩散速度。利用分子动力学模拟,对山梨醇-烷基胺表面活性剂/甘油体系的能量演化及表面活性剂相对于固体表面距离的分布进行了研究。这项目工作不仅为抑制液滴在植物叶面的弹跳飞溅提供了一种建设性的方法,而且为选择农用表面活性剂提供了理论基础。