Mechanochemical Synthesis of Corannulene-Based Curved Nanographenes

It is shown that corannulene-based strained π-surfaces can be obtained through the use of mechanochemical Suzuki and Scholl reactions. Besides being solvent-free, the mechanochemical synthesis is high-yielding, fast, and scalable. Therefore, gram-scale preparation can be carried out in a facile and sustainable manner. The synthesized nanographene structure carries positive (bowl-like) and negative (saddle-like) Gaussian curvatures and adopts an overall quasi-monkey saddle-type of geometry. In terms of properties, the non-planar surface exhibits a high electron affinity that was measured by cyclic voltammetry, with electrolysis and in situ UV/vis spectroscopy experiments indicating that the one-electron reduced state displays a long lifetime in solution. Overall, these results indicate the future potential of mechanochemistry in accessing synthetically challenging and functional curved π-systems.     

Mechanochemical Synthesis of Catalytic Materials

The mechanochemical synthesis of nanomaterials for catalytic applications is a growing research field due to its simplicity, scalability, and eco-friendliness. Besides, it provides materials with distinct features, such as nanocrystallinity, high defect concentration, and close interaction of the components in a system, which are, in most cases, unattainable by conventional routes. Consequently, this research field has recently become highly popular, particularly for the preparation of catalytic materials for various applications, ranging from chemical production over energy conversion catalysis to environmental protection. In this Review, recent studies on mechanochemistry for the synthesis of catalytic materials are discussed. Emphasis is placed on the straightforwardness of the mechanochemical route—in contrast to more conventional synthesis—in fabricating the materials, which otherwise often require harsh conditions. Distinct material properties achieved by mechanochemistry are related to their improved catalytic performance.     

铁酸锌纳米晶的机械化学合成

以αFe₂O₃和ZnO粉体为原料,在高能球磨的作用下,室温(约25℃)合成了铁酸锌(ZnFe₂O₄)纳米晶.用XRD、TEM、M?sbauer谱及IR光谱等方法对纳米晶进行了表征.结果表明:所得纳米晶具有非正型分布的尖晶石结构,为超顺磁性;纳米晶内存在着较多的缺陷.     

Effective Mechanochemical Synthesis of [60]Fullerols

Abstract

[60]Fullerols which show an average composition of C₆₀(OH)_27.2 were synthesized effectively in high yield under the high-speed vibration milling (HSVM) conditions in air at room temperature.     

Mechanochemical tools in the synthesis of organometallic compounds

In response to rising environmental concerns, chemistry is experiencing a considerable change in both concepts and practices to adopt more efficient and sustainable technologies. One of the alternative technologies that offer many advantages over the conventional solution-based techniques is mechanochemistry which utilizes mechanical energy to induce chemical reactions. Despite the fact that mechanochemistry has reached high significance in the creation of advanced materials, such as alloys, ceramics, electrode materials, and nanocomposites, in the field of small molecule synthesis its potential remains largely untapped. This review highlights the opportunities and prospects of different mechanochemical tools in the synthesis of organometallic compounds, including transition metal complexes with N-heterocyclic carbene, arene, and cyclopentadienyl ligands, monometallacyclic and pincer derivatives, as well as main group metal compounds (e.g., allyl complexes and the Grignard reagents). Many important organometallic transformations such as C–H bond metalation, transmetalation, and oxidative addition can be successfully implemented under mechanochemical conditions in a highly productive and energy-saving manner. Furthermore, the postmodification of metal-containing species upon grinding or milling is shown to be a powerful route to both new discrete metal complexes and different supramolecular architectures (metal-containing organic cages, macrocylces, networks).     

Mechanochemical Pretreatment for Efficient Solvent-Free Synthesis of SSZ-13 Zeolite

The economical and environmentally benign synthesis of SSZ-13 zeolite was possible due to the mechanochemical activation of dry reagents by planetary mill. Contrary to manual grinding in a mortar, the proposed automatized approach is scalable and reproducible. This solvent-free process provided a huge gain in product/gel ratios, significantly minimized reaction space and organic structure-directing agent use, and allowed for the elimination of agitation. Obtained materials were comparable to the product of “classical” syntheses. The use of different silica sources resulted in SSZ-13 zeolites with various characteristics: different Si/Al ratio and crystal size.     

Solvent-Free Mechanochemical Synthesis of High Transition Biphenyltetracarboxydiimide Liquid Crystals

A series of high temperature alkyl and alkoxy biphenyltetracarboxydiimide liquid crystals have been prepared under ball mill method using solvent-free mechanochemical approach. The thermal properties of the prepared compounds were investigated by deferential scanning calorimetry (DSC) measurements and the textures were identified by polarized optical microscope (POM). The compounds showed smectic mesomorphic behaviour. The results showed the increasing nature of transition temperature Cr-SmC with chain length with increments of the SmC mesophase range. However, the mesophase range of the SmA was decreased with the terminal chain length either for the alkyl or alkoxy terminal groups. Moreover, the DFT theoretical calculations have been conducted give a detailed projection of the structure of the prepared compounds. A conformational investigation of the biphenyl part has been studied. A deep illustration of the experimental mesomorphic behaviour has been discussed in terms of the calculated aspect ratio. A projection of the frontier molecular orbitals as well as molecular electrostatic potential has been studied to show the effect of the polarity of the terminal chains on the level and the gap of the FMOs and the distribution of electrostatic charges on the prepared molecules.     

Mechanochemical Activation of Zinc and Application to Negishi Cross‐Coupling

A form independent activation of zinc, concomitant generation of organozinc species and engagement in a Negishi cross‐coupling reaction via mechanochemical methods is reported. The reported method exhibits a broad substrate scope for both C(sp³)–C(sp²) and C(sp²)–C(sp²) couplings and is tolerant to many important functional groups. The method may offer broad reaching opportunities for the in situ generation organometallic compounds from base metals and their concomitant engagement in synthetic reactions via mechanochemical methods.     

Efficient Synthesis of Highly Functionalized Thiazolidine-4-ones Under Solvent-Free Conditions

Summary. 4-Phenylthiosemicarbazide reacts smoothly with dimethyl acetylenedicarboxylate in the presence of aldehydes or ketones under solvent free conditions to produce highly functionalized thiazolidine-4-ones.     

两个天然查尔酮苷的全合成

以香草酮和对羟基苯甲醛为原料,经酚羟基保护、羟醛缩合、相转移催化法接糖、去保护基等反应合成了两个天然查尔酮苷——4’-O-β-D-喃葡萄基-3’-甲氧基-4-甲氧基-查尔酮和4’-O-β-D-喃葡萄基-3’-甲氧基-4-羟基-查尔酮,总收率分别为17.2%和20.8%,其结构经1H NMR,13C NMR和HR-MS确证。在脱保护基反应中,首次提出了NH4Cl脱除MOM保护基的新方法。     

无溶剂法合成杯[4]芳烯星形化合物

以对苯二甲醛、乙酸酐为原料合成对苯二甲醛单缩醛, 接着与间苯二酚反应, 制备了含醛基杯[4]芳烯. 利用季戊四醇与含醛基杯[4]芳烯反应, 进而再与3-[4-(2,5-二氧杂环戊基)苯基]-9-[4-二(甲羰氧基)甲基苯基]-2,4,8,10-四氧杂螺环[5.5]十一烷反应, 合成了杯[4]芳烯星形化合物, 收率为65.2%. 产品结构经 IR, ¹H NMR, MS 和元素分析进行了表征.     

CuI/TMEDA催化合成芳基葡萄糖碳苷化合物

以THF为溶剂, CuI/TMEDA为催化剂,四乙酰溴代葡萄糖与芳基溴化镁经取代反应合成了芳基葡萄糖碳苷（2a~2c）,其结构经¹H NMR和¹³C NMR确证。该方法立体选择性较好。在最佳反应条件(THF为溶剂,10% CuI和10% TMEDA为催化剂,于0 ℃反应至终点)下,2a~2c的收率为58%~71%, α/β为1/6.5~1/7.1。     

First Synthesis of Bioactive Diphyllin Glycosides Isolated from Justicia patentiflor Hemsl

The syntheses of three naturally occurring diphyllin glycosides have been achieved. 7-O-β-D-Qtfmovopyranosyldiphyllin （patentiflorin A） and 7-O-β-L-fucopyranosyldiphyllin （patentiflorin B） were synthesized by the glycosylation of diphyllin with peracetylglycosyl bromides under phase transfer catalysis （PTC） conditions. 4＂-O-Acetyl-7-O-β-L-fucopyranosyldiphyllin （4＂-O-acetyl patentiflorin B） was obtained from patentiflorin B on an orthoesterification-orthoester rearrangement approach. Their ^1H NMR, ^13C NMR and HRMS signals are all consistent with those reported for the natural product.     

Synthesis and Characterization of Novel Aryl Cyclitols: Polycyclitols

New polycyclitols were synthesized starting from 1,4-naphthoquinone. An endo-selective Diels–Alder cycloaddition between 1,4-naphthoquinone and 1-acetoxybutadiene afforded a diketone. Reduction of the diketone with a NaBH₄-CeCl₃ · 7H₂O system gave a new cyclitol analog diol acetate. Acetylation of this compound afforded a triacetate. Oxidation of the double bond of the triacetate compound with OsO₄ followed by acetylation of hydroxyl groups gave the pentaacetate, whose structure was established unequivocally via application of x-ray crystallographic methods. Hydrolysis of ester groups of pentaacetate under basic condutions furnished the desired and another novel aryl cyclitol.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource: Full experimental and spectral details.]     

Mechanochemical Synthesis and Characterization of Hydrated and Dehydrated Crystalline Strontium Terephtalates

A successful mechanochemical synthesis of strontium terephthalate trihydrate is described for the first time. The dehydration of Sr(C₈H₄O₄) · 3H₂O occurs at about 100 °C and results in a well‐defined strontium terephtalate, Sr(C₈H₄O₄), thermally stable up to 550 °C. Both compounds are not described so far in the literature. Their structures were solved by ab initio structure determination and subsequent Rietveld refinement of the powder diffraction data. Further methods like DTA‐TG, MAS NMR and FT‐IR spectroscopy, and BET measurements were used to characterize these compounds.     

Mechanochemical syntheses as an example of green processes

Presented work describes mechanical treatment as a non-conventional solid-state process for preparation of some functional materials. Mechanochemical syntheses may be alternative as waste-free and ecologically safer methods of preparing pigments, composites, catalysts, biomaterials, which obey main principles of Green Chemistry.     

One-Pot Synthesis of Mannich Bases Under Solvent-Free Conditions

A mild and practically convenient one-pot procedure for the Mannich reaction via condensation of amines, aldehydes and malonates, β-ketoesters, or β-dicarbonyl compounds has been carried out without using any organic solvent, metallic catalyst, or Lewis acids or bases at room temperature. The present protocol offers several advantages, such as goods yields, simple procedure with easy workup, and the absence of any volatile, hazardous organic solvents and metallic catalyst.     

Efficient and Facile Synthesis of 3-Amino-1-aryl-9H-fluorene-2,4-dicarbonitrile Under Solvent-Free Conditions

A versatile and efficient route to 3-amino-1-aryl-9H-fluorene-2,4-dicarbonitrile via multicomponent reactions of 1-indanone, aromatic aldehydes, and malononitrile under solvent-free conditions using NaOH as the catalyst is described. This method provides several advantages over alternative procedures such as mild, solvent-free conditions at ambient temperature and direct isolation of the products in good yields.