Methane coupling in microwave plasma under atmospheric pressure

Methane coupling in microwave plasma under atmospheric pressure has been investigated.The effects of molar ratio n（CH4）/n（H2）,flow rate and microwave power on the reaction have been studied.（1）With the decrease of n（CH4）/n（H2）ratio,methane conversion,C2 hydrocarbon yield,energy yield and space-time yield of acetylene increased,but the yield of carbon deposit decreased.（2）With the increase of microwave power,energy yield of acetylene decreased,but space-time yield of acetylene increased.（3）With the increase of flow rate,energy yield and space-time yield of acetylene increased first and then decreased.Finally,under the reaction conditions of CH4 flow rate of 700 mL/min,n（CH4）/n（H2）ratio of 1/4 and microwave power of 400 W,the energy yield and space-time yield of acetylene could reach 0.337 mmol/kJ and 12.3 mol/（s m3）,respectively.The reaction mechanism of methane coupling in microwave plasma has been investigated based on the thermodynamics of chemical reaction.Interestingly,the acetylene yield of methane coupling in microwave plasma was much higher than the maximum thermodynamic yield of acetylene.This phenomenon was tentatively explained from non-expansion work in the microwave plasma system.

KF-Melamine Formaldehyde Resin （KF-MFR） as a Versatile and Efficient Heterogeneous Reagent for Aldol Condensation of Aldehydes and Ketones under Microwave Irradiation

KF-Melamine formaldehyde resin （KF-MFR） was demonstrated to be a highly efficient heterogenious catalyst for cross-aldol condensation under microwave irradiation. In this synthesis, various aldehydes and ketones were condensed together in the presence of supported KF on melamine-formaldehyde resin to afford different chalcone derivatives in good to excellent yields. KF-MFR proved to have unique termal and chemical resistance and can be reused for many consecutive runs without remarkable loss in catalytic activity.

Iron catalyzed Michael addition: Chloroferrate ionic liquids as efficient catalysts under microwave conditions

The iron containing ionic liquid 1-butyl-3-methylimidazolium tetrachloroferrate （[C4mim]C1/FeCl3; Z = 0.5） proved to be an efficient catalyst for the solvent-free metal catalyzed Michael addition of β-keto esters and enones. Due to the ionic structure of the catalyst, a significant acceleration of the reaction rate was observed under microwave conditions. Furthermore, recycling of the ionic liquid catalyst could be performed after simply distilling off the products.

Highly Efficient Microwave-Assisted Substitution of β-Dicarbonyl Compounds with Secondary Alcohols Using Fluoroboric Acid as the Catalyst

The microwave-assisted substitution of β-dicarbonyl compounds with secondary alcohols has been achieved efficiently, using very cheap fluoroboric acid （HBF4） as the catalyst. For various β-dicarbonyl compounds and a series of secondary alcohols, the direct substitution gives high yields after only 5 min of microwave irradiation.

[BMIM]CI Catalyzed One-Pot Synthesis of a-Aminophospho- nate Derivatives Containing a 4-Phenoxyquinazoline Moiety under Microwave Irradiation

[BMIM]Cl catalyzed three component Mannich-type reaction of 4-（quinazolin-4-yloxy）benzenamine and aldehyde with dialkyl phosphite under microwave irradiation has been described. The salient features of the reaction leading to new a-aminophosphonates include shorter reaction time and good yields. The method is environmentally friendly and does not require toxic catalysts or solvents. To the best of our knowledge, this is the first report for [BMIM]Cl induced one-pot synthesis of a-aminophosphonate derivatives.

Microwave-Assisted Aqueous Synthesis： A Rapid Approach to Poly-functionalized Indoline-Spiro Benzofurodiazepines

New cycloaddition has been established for the synthesis of indoline-spiro benzofurodiazepine derivatives. Those reactions were conducted by reacting readily available and inexpensive starting materials, such as ben- zene- 1,2-diamines, tetronic acid and indoline-2,3-diones, in aqueous solution under microwave irradiation. When mono-substituted benzene-l,2-diamines as an amine component was employed, the reaction regioselectively re- sulted in the poly-functionalized indoline-spiro benzofurodiazepine with good yields. The present green synthesis shows attractive characteristics such as the use of water as reaction media, concise one-pot conditions, short reaction periods, easy work-up/purification and reduced waste production without the use of any strong acids or metal promoters.

Two-dimensional SnO_2/graphene heterostructures for highly reversible electrochemical lithium storage

The ever-growing market demands for lithium ion batteries have stimulated numerous research efforts aiming at the exploration of novel electrode materials with higher capacity and long-term cycling stability.Two-dimensional (2D)nanomaterials and their heterostructures are an intense area of study and promise great potential in electrochemical lithium storage owing to their unique properties that result from structural planar confinement.Here we report a microwave chemistry strategy to integrate ultrathin SnO2 nanosheets into graphene layer to construct surface-to-surface 2D heterostructured architectures,which can provide unique structural planar confinement for highly reversible electrochemical lithium storage.The as-synthesized 2D SnO2/graphene heterostructures can exhibit high reversible capacity of 688.5mAh g^-1 over 500cycles with excellent long-term cycling stability and good rate capability when used as anode materials for lithium ion batteries.The present work definitely reveals the advantages of 2D heterostructures featured with a surface-to-surface stack between two different nanosheets in energy storage and conversion devices.

Synthesis and characterization of NaA zeolite particle as intumescent fiame retardant in chloroprene rubber system

NaA zeolite with average particle size of 1 μm was successfully synthesized by microwave heating. Influences of pre-crystallization time, microwave power and microwave heating time on the synthesis of NaA zeolite were investigated. The as-synthesized sample was characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM） and particle size distribution （PSD）. Thermal and flame retardant properties as intumescent flame retardant （IFR） in chloroprene rubber （CR） system, such as thermogravimetry （TG）, limiting oxygen index （LOI）, burning rate （BR） and specific extinction area （SEA） were further investigated by adding NaA zeolite particles to CR. Experimental results show that the thermal stability and LO1 value increased while BR and SEA decreased by adding 5 phr NaA zeolite into the 40 phr IFR filled CR system.

Synthesis and Antioxidant Activities of Novel 4,4＇-Arylmethylene-bis（1H-pyrazole-5-ol）s from Lignin

A series of novel bispyrazoles joined by arylmethylene at C-4 position were synthesized with aromatic aldehydes obtained from lignin and screened for their in vitro antioxidant activities by N,N-diphenyl-N＇picrylhydrazyl （DPPH） and 2,2＇-azino-bis（3-ethylenzothiazoline-sulphonic acid） diammonium salt （ABTS＋） radical scavenging assays. All of these compounds exhibited good DPPH and ABST＋ radical scavenging activities as compared to the standard, Trolox, which suggested their potential as promising agents for cturing tumors or other free radical-related diseases.

Cyclization of 4,5-Diamino Pyrazole Derivatives and Their Antibacterial Activities

A convenient synthesis of intermediate 4,5-diamino-3-aryl-l-phenylpyrazoles 4a--4c was reported. The different cyclization reactions were carried out with chalcone, 2-mercaptoacetic acid and p-anisialdehyde, ethyl chloroformate, glyoxal and thiourea to afford different N and S containing heterocycles. The reaction conditions were compared by conventional heating and microwave irradiation. The structures of the cyclization products were de- termined by analytical and spectroscopic data. All the synthesized compounds were screened for antibacterial activities in vitro.