Click approach to the three‐component synthesis of novel β‐hydroxy‐1,2,3‐triazoles catalysed by new (Cu/Cu2O) nanostructure as a ligand‐free,green and regioselective nanocatalyst in water

Copper nanostructures were produced as an effective and regioselective catalyst for the synthesis of 1,2,3‐triazoles from a wide range of raw materials, such as sodium azide, epoxides and terminal alkynes, in water via a one‐pot three‐component click reaction. The new heterogeneous catalyst was prepared by a simple ball mill reduction of CuO with NaBH₄ using a ball‐to‐powder weight ratio of 50:1 under air atmosphere at room temperature. The catalyst was fully characterized using scanning electron microscopy, energy‐dispersive X‐ray analysis, Fourier transform infrared spectroscopy and X‐ray diffraction. The copper nanostructures catalysed both ring opening and triazole cyclization steps. Products were obtained in high yields and short reaction times. The reactions were performed at ambient temperature in water as a green solvent. The Cu/Cu₂O nanostructures revealed high reusability and high stability via a simple recycling process.     

Preparation of chiral amino esters by asymmetric phase-transfer catalyzed alkylations of Schiff bases in a ball mill

The asymmetric alkylation of Schiff bases under basic conditions in a ball mill was performed. The starting Schiff bases of glycine were prepared beforehand by milling protected glycine hydrochloride and benzophenone imine, in the absence of solvent. The Schiff base was then reacted with a halogenated derivative in a ball mill in the presence of KOH. By adding a chiral ammonium salt derived from cinchonidine, the reaction proceeded asymmetrically under phase-transfer catalysis conditions, giving excellent yields and enantiomeric excesses up to 75?%. Because an equimolar amount of starting material was used, purification was greatly simplified.     

Preparation of Chiral Amino Esters by Asymmetric Phase‐Transfer Catalyzed Alkylations of Schiff Bases in a Ball Mill

The asymmetric alkylation of Schiff bases under basic conditions in a ball mill was performed. The starting Schiff bases of glycine were prepared beforehand by milling protected glycine hydrochloride and benzophenone imine, in the absence of solvent. The Schiff base was then reacted with a halogenated derivative in a ball mill in the presence of KOH. By adding a chiral ammonium salt derived from cinchonidine, the reaction proceeded asymmetrically under phase‐transfer catalysis conditions, giving excellent yields and enantiomeric excesses up to 75 %. Because an equimolar amount of starting material was used, purification was greatly simplified.     

Switchable selectivity during oxidation of anilines in a ball mill

A solvent-free method for the direct oxidation of anilines to the corresponding azo and azoxy homocoupling products by using a planetary ball mill was developed. Various oxidants and grinding auxiliaries were tested and a variety of substituted anilines were investigated. It was possible to form chemoselectively either azo, azoxy, or the nitro compounds from reaction of aromatic anilines. The selectivity of the solvent-free reaction is switchable by applying a combination of oxidant and grinding auxiliary. Furthermore, a comparison with other methods of energy input (microwave, classical heating, and ultrasound) highlighted the advantages of the ball mill approach and its high energy efficiency.     

Improvement of dissolution property of poorly water-soluble drug by novel dry coating method using planetary ball mill

The dissolution property of a poorly water-soluble drug, flurbiprofen (FP), was improved by a novel dry coating method using a planetary ball mill. Several mixtures composed of water-soluble additives (D-mannitol, lactose, and erythritol), light anhydrous silicic acid, and flurbiprofen were prepared. These mixtures and several starches were co-ground in a planetary ball mill, and the surface of the starches was dry coated with the mixtures. The size, appearance, yield, and drug dissolution property of the dry coated preparations were evaluated, and the optimal formulation which improved the dissolution property of poorly water-soluble flurbiprofen was determined. The dissolution rate of FP was increased by dry coating of the surface of starches with microparticulated FP. It was further increased by co-grinding of FP, starch, and a water-soluble additive, or dry coating of the starch surface with microparticulated FP and light anhydrous silicic acid, as a glidant. These co-ground and dry coated preparations could be recovered from the pot of the planetary ball mill readily without adhesion to the inside wall of the pot. These are considered to be novel, industrially applicable methods for improving the dissolution rate of poorly water-soluble drugs.     

Ball Milling Pretreatment of Oil Palm Biomass for Enhancing Enzymatic Hydrolysis

Oil palm biomass, namely empty fruit bunch and frond fiber, were pretreated using a planetary ball mill. Particle sizes and crystallinity index values of the oil palm biomass were significantly reduced with extended ball mill processing time. The treatment efficiency was evaluated by the generation of glucose, xylose, and total sugar conversion yields from the pretreatment process compared to the amount of sugars from raw materials. Glucose and xylose contents were determined using high-performance liquid chromatography. An increasing trend in glucose and xylose yield as well as total sugar conversion yield was observed with decreasing particle size and crystallinity index. Oil palm frond fiber exhibited the best material yields using ball milling pretreatment with generated glucose, xylose, and total sugar conversion yields of 87.0, 81.6, and 85.4 %, respectively. In contrast, oil palm empty fruit bunch afforded glucose and xylose of 70.0 and 82.3 %, respectively. The results obtained in this study showed that ball mill-treated oil palm biomass is a suitable pretreatment method for high conversion of glucose and xylose.     

The effect of mechanical activation on the hydration properties of nanodispersed silica

The hydration of highly dispersed nanosize silica was studied by low-temperature ¹H NMR spectroscopy before and after the mechanical activation in a ball mill.     

Rapid synthesis of nucleotide pyrophosphate linkages in a ball mill

Using a ball mill, rapid, atom-economic coupling between adenosine-5'-phosphoromorpholidate and phosphorylated ribose derivatives as their sodium or barium salts was achieved. Facile purification by reversed-phase HPLC enabled product isolation within hours.     

Mechanochemical Synthesis as an Alternative Effective Technique for the Preparation of the Composite Catalysts

Kinetics and Catalysis - —Mechanochemical synthesis in a ball mill was applied for the nanocomposite Cu(CuO)–CeO2 catalyst preparation from CeO2 and following dopants: Cu metal and...     

Solventless protocol for efficient bis-N-boc protection of adenosine, cytidine, and guanosine derivatives

A solvent-free reaction employing a simple low-energy ball mill apparatus converts the amino groups of adenosine, 2-deoxyadenosine, cytidine, 2-deoxycytidine, guanosine, and 2-deoxyguanosine as well as some of their ribosyl O-protected derivatives to the corresponding bis-N-Boc carbamates. In the case of guanosine compounds, the carbonyl group of the base moiety was also blocked as its O-Boc enol carbonate. A variation of this approach using transient in situ O-silylation permitted the preparation of bis-N-Boc nucleosides in which the sugar hydroxyls were unprotected. The ball mill reactions were rapid, convenient, and very high-yielding except in the case of the guanosine compounds. This highly efficient method protects the amino groups of these nucleosides with a base stable and acid labile group suitable for further synthetic manipulation.     

Hydroamination Reactions of Alkynes with ortho‐Substituted Anilines in Ball Mills: Synthesis of Benzannulated N‐Heterocycles by a Cascade Reaction

It was demonstrated that ortho‐substituted anilines are prone to undergo hydroamination reactions with diethyl acetylenedicarboxylate in a planetary ball mill. A sequential coupling of the intermolecular hydroamination reaction with intramolecular ring closure was utilized for the syntheses of benzooxazines, quinoxalines, and benzothiazines from readily available building blocks, that is, electrophilic alkynes and anilines with OH, NH, or SH groups in the ortho position. For the heterocycle formation, it was shown that several stress conditions were able to initiate the reaction in the solid state. Processing in a ball mill seemed to be advantageous over comminution with mortar and pestle with respect to process control. In the latter case, significant postreaction modification occurred during solid‐state analysis. Cryogenic milling proved to have an adverse effect on the molecular transformation of the reagents.     

The mechanochemical reactions between CsF and kaolinite

The grinding of a mixture containing kaolinite and CsF was carried out by three different techniques, short manual grinding, Fisher mechanical mortar and Retsch ball mill. In addition to different cesium aluminium silicates which were detected by X-ray powder diffraction, a new type of intercalation complex was identified by FTIR spectroscopy. The X-ray diffractogram of this complex did not show any basal spacing, which may characterize the complex but the 0.715 nm characteristic peak of the untreated kaolinite became very weak. The Retsch ball mill led to a slight destruction of the kaolinite and the formation of small amounts of the new intercalation complex. The delamination of book-like kaolinite assemblages was observed after the manual and Fisher mortar grindings. In the latter grinding techniques the kaolin-like layers persisted and served as the framework for the intercalation complexes. Received: 4 February 1998 Accepted: 11 March 1998     

A novel dry route to ortho-functionalized triarylbismuthanes that are difficult to access by conventional wet routes

When an aryl iodide bearing an electron-withdrawing group at the ortho position was milled together with bismuth shots and calcite grains in the presence of Cu powder and CuI using a laboratory ball mill, the corresponding ortho-functionalized triarylbismuthane was obtained in moderate to good yield.     

Supramolecular click procedures in liquid crystals

ABSTRACT

Click reactions have been introduced as highly reliable chemical processes, in which even complex molecular building blocks can be connected irreversibly by covalent bonds. Although reversible processes like supramolecular aggregation controlled by specific interactions like hydrogen bonding or metal complexation are also highly reliable and omnipresent in nature, they are rarely considered as click reactions. Mechanical processes in daily life associated with a click procedure depending only on shape recognition and space-filling are snap fasteners, snap fit buckels and ball detents and they are almost unknown in the nanoworld. This account defines such processes on a molecular basis and highlights some recent examples of star-shaped, shape-persistent mesogens designed to control the nanostructure of columnar liquid crystals for future photovoltaic applications. The click procedure leading to these structures is compared to related systems like the CPI and the LC shuttlecock.     

Chelation-assisted method for the preparation of cathode material LiFePO<Subscript>4</Subscript>

LiFePO₄/C composite cathode material is prepared by ball milling with the assistance of EDTA chelation with using water as the media of ball mill procedure. FePO₄ and LiOH are used as starting materials; a certain amount of glucose is used as carbon sources and reduction agent. The structure and morphology of the composite are characterized by X-ray diffraction and scanning electron microscopy. Cyclic voltammetry, AC impedance measurements, and galvanostatic charge–discharge and cycling performances are used to characterize its electrochemical properties. The results indicate that the performances of composites prepared by chelation-assisted method are much better than common ball milling method which using alcohol or acetone as the media of ball mill procedure. The stable discharge capacity of the prepared composite is 150 and 105 mAh g⁻¹ at 1 and 10 C rate, respectively.     

The Influence of Mechanical Activation on Hydrogen Absorption by Intermetallic Compound LaNi2.5Co2.4Mn0.1

Russian Journal of Physical Chemistry A - The influence of mechanical activation in a high energy planetary ball mill on hydrogen sorption and structural properties of intermetallic compound...     

Mechanically Activated Solid-Phase Reaction of Copper(I) Chloride with Sodium β-Diketonates: Formation of Metallic Copper Nanoparticles

Russian Journal of General Chemistry - Solid-phase reaction of copper(I) chloride with sodium β-diketonates under mechanical activation in a vibration ball mill involves disproportionation of...     

Catalyst- and solvent-free mechanochemical synthesis of isoxazoles from N-hydroxybenzimidoyl chlorides and enamino carbonyl compounds

A regioselective, solvent-free and catalyst-free synthesis of isoxazoles has been successfully developed under ball milling conditions. Milling the mixtures of N-hydroxybenzimidoyl chlorides and enamino carbonyl compounds in a ball mill at a frequency of 14.6?Hz for 20–60?min afforded isoxazoles in up to 86% yields. A possible reaction mechanism leading to the formation of the observed isoxazoles is proposed.     

Application of Ball Milling Technology to Carbohydrate Reactions‐II. Solvent‐Free Mechanochemical Synthesis of Glycosyl Azides‡

Glycosyl azides have been prepared from a range of readily available glycosyl halides by a solvent‐free mechanochemical procedure employing a planetary ball mill in good to excellent yields.     

Mechanochemical synthesis and high-frequency induction heated consolidation of nanostructured Ti5Si3 and its mechanical properties

Pure Ti and Si powders were milled in a horizontal-rotation ball mill and in a high-energy ball mill to synthesize Ti₅Si₃ powders. The high-energy ball milling produced nanosized single-phase Ti₅Si₃ particles. Meanwhile, no reaction occurred during the horizontal milling. The two milled powders were consolidated using the high-frequency induction heated sintering method. A dense nanostructured Ti₅Si₃ compact was consolidated within 2 min using the mechanically synthesized Ti₅Si₃ powder. The retainment of nanoscale structure during sintering is believed to be the reason for the good mechanical properties of the Ti₅Si₃ compact. In comparison, the horizontally milled powder reacted to form Ti₅Si₃ partially on sintering. It is believed that the enhanced toughness of the horizontally milled samples may be due to the crack-deterring effect of softer Si/Ti grains.