A high-yield microwave heating method for the preparation of (phthalocyaninato)bis(chloro)silicon(IV)

2001 ◽  
Vol 05 (04) ◽  
pp. 376-380 ◽  
Author(s):  
DOMINIC A. DAVIES ◽  
CHRISTINA SCHNIK ◽  
JACK SILVER ◽  
JOSE L. SOSA-SANCHEZ ◽  
PHILIP G. RIBY
Keyword(s):  
Reaction Time ◽  
Microwave Heating ◽  
Silicon Tetrachloride ◽  
Conventional Heating ◽  
High Yield ◽  
Thermal Heating ◽  
Heating Method ◽  
Purification Time

The microwave heating synthesis of (phthalocyaninato)bis(chloro)silicon(IV) prepared from diiminoisoindolene and silicon tetrachloride in quinoline has been shown to be rapid (5 min reaction time compared to 30 min with thermal heating) and results in a high yield (91% compared to 71% using thermal heating). A modified microwave ashing furnace was used to heat the reaction mixture. The high yield has led to a reduction in the purification time to 1 h (compared to 4 h or more using conventional heating).

Comparative study of conventional and microwave heating of polyacrylonitrile-based fibres

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Guozhen Zhao ◽  
Jianhua Liu ◽  
Lei Xu ◽  
Shenghui Guo
Keyword(s):  
Microwave Heating ◽  
Surface Defects ◽  
Energy Dispersive Spectrometer ◽  
Xrd Analysis ◽  
Economic Benefits ◽  
Heating Time ◽  
Oxidation Temperature ◽  
Conventional Heating ◽  
Heating Method ◽  
Molecular Arrangement

Abstract The effects of the conventional heating method and the microwave heating method on polyacrylonitrile-based fibres in the temperature range of 180–280 °C were investigated. Fourier transform infrared spectroscopy, X-ray wide-angle scattering, Raman spectroscopy, energy-dispersive spectrometer, scanning electron microscopy and bulk density were used to characterise the properties of the samples. Results show that the microwave heating method can shorten the pre-oxidation time, reduce pre-oxidation temperature and reduce the number of surface defects. The pre-oxidised fibres obtained by the microwave heating method exhibit not only good crystallite size but also a smooth surface. Atomic morphology and molecular arrangement are orderly inside the fibre. The FT-IR spectrum shows that the oxidation reaction occurs at 220 °C, and the CI value of PAN fibers stabilised by microwave heating is the larger than the fibers stabilised by conventional heating. XRD analysis shows that fibers stabilised by microwave heating have low stack domains. The SEM and Raman spectra indicate that hydrogen peroxide can improve the surface finish of the fibers and reduce defects. Microwave heating can reduce the pre-oxidation temperature by about 20 °C and shorten the heating time. The economic benefits of using this method are significantly improved.

First Sustainable Aziridination of Olefins Using Recyclable Copper-Immobilized Magnetic Nanoparticles

Synlett ◽  
2019 ◽  
Vol 30 (05) ◽  
pp. 563-566 ◽  
Author(s):  
Sylvestre Toumieux ◽  
Mohamad Khodadadi ◽  
Gwladys Pourceau ◽  
Matthieu Becuwe ◽  
Anne Wadouachi
Keyword(s):  
Magnetic Nanoparticles ◽  
Reaction Time ◽  
Microwave Irradiation ◽  
Significant Loss ◽  
Conventional Heating ◽  
Heating Method ◽  
Magnetic Extraction

The first copper-catalyzed aziridination of olefins using re­cyclable magnetic nanoparticles is described. Magnetic nanoparticles were modified with dopamine and used as a support to coordinate copper. The methodology was optimized with styrene as olefin and using [N-(p-toluenesulfonyl)imino]phenyliodinane (PhI=NTs) as nitrene source. A microwave irradiation decreased the reaction time by 4-fold compared to conventional heating method. The catalyst was recovered by simple magnetic extraction and could be reused successfully up to five times without significant loss of activity. The methodology was ­applied to a range of different olefins leading to moderate to excellent yields in the formation of the expected aziridine.

SiC Platelets Synthesized by Powder-Heating Technique

2007 ◽  
Vol 336-338 ◽  
pp. 939-941
Author(s):  
Yong Qiang Meng ◽  
Zhi Min Bai ◽  
Chang Hong Dai ◽  
Bao Bao Zhang
Keyword(s):  
Silicon Carbide ◽  
Reaction Time ◽  
Carbon Black ◽  
Raw Materials ◽  
Low Cost ◽  
Average Diameter ◽  
New Method ◽  
Conventional Heating ◽  
High Yield ◽  
Sio2 Powder

A new method for producing silicon carbide platelets with low cost and high yield was introduced. The silicon carbide platelets were synthesized by powder-heating techniques with carbon black and SiO2 powder as raw materials and CoCl2 as catalyst. The starting mixtures were heated at a temperature in the range of 1800-2000°C for the duration of about 2-4h to produce substantially completely unagglomerated silicon carbide platelets with a thickness of 5-20μm and the average diameter of 50-200μm. Compared to the conventional heating, the powder-heating technique is advantageous of less investment on equipment, easy to manufacture and convenient to operate. Furthermore, it is very suitable for realizing the scaled production because of the lower synthesizing temperature, shorter reaction time and greater output.

Synthesis of anti-inflammatory 2,3-unsaturated O-glycosides using conventional and microwave heating techniques

2017 ◽  
Vol 23 (3) ◽  
pp. 205-211
Author(s):  
Adriana Cristina N. de Melo ◽  
Ronaldo N. de Oliveira ◽  
João R. de Freitas Filho ◽  
Teresinha G. da Silva ◽  
Rajendra M. Srivastava
Keyword(s):  
Reaction Time ◽  
Microwave Irradiation ◽  
Microwave Heating ◽  
Acid Catalyst ◽  
Conventional Heating ◽  
Microwave Exposure ◽  
Ferrier Rearrangement ◽  
Acetyl Group ◽  
Anti Inflammatory

AbstractThe preparation of eight 2,3-unsaturated O-glycosides from D-glycals and alcohols, using montmorillonite K-10 as an acid catalyst, is described. The Ferrier rearrangement products were obtained in good yields using conventional heating and microwave irradiation but the reaction time was substantially reduced employing the latter procedure. The yields were slightly lower under microwave exposure. Five of the di-O-acetylated products were deacetylated to the glycosides in excellent yields. The acetylated products possess good anti-inflammatory property suggesting that the acetyl group plays an important role in reducing the inflammation. Among the compounds tested, glycosides containing thiophene as an aglycone present much better inflammation reducing characteristics than the analogues without this function.

Microwave-assisted Al-substituted Tobermorite Synthesis

2000 ◽  
Vol 15 (4) ◽  
pp. 850-853 ◽  
Author(s):  
Michihiro Miyake ◽  
Shigeto Niiya ◽  
Motohide Matsuda
Keyword(s):  
Reaction Time ◽  
Hydrothermal Synthesis ◽  
Microwave Heating ◽  
Conventional Heating ◽  
Crystallization Time ◽  
Short Reaction Time ◽  
Microwave Assisted

The effect of microwave heating on the hydrothermal synthesis of Al-substituted tobermorite and the removal characteristics of resulting materials were examined and compared with the effect of conventional heating. The microwave heating reduced the crystallization time of Al-substituted tobermorite—i.e., Al-substituted tobermorite was synthesized within 80 min at around 140 °C—and produced smaller crystallites than the conventional heating. The minute crystallites were found to promote the removal characteristics for Cs+ ions in short reaction time.

scholarly journals High efficiency extractions of V, Cr, Ti, Fe and Mn from vanadium slag by microwave heating

2021 ◽  
pp. 23-23
Author(s):  
B. Tan ◽  
S. Wu ◽  
L.-J. Wang ◽  
K.-C. Chou
Keyword(s):  
High Temperature ◽  
Reaction Time ◽  
Diffusion Process ◽  
Microwave Heating ◽  
High Efficiency ◽  
Conventional Heating ◽  
Vanadium Slag ◽  
Reduction Processes ◽  
Fe And Mn ◽  
Speed Up

The vanadium slag (V-slag) is generated from smelting vanadium titanomagnetite ore, which contains valuable elements, such as V, Ti, Cr, Fe and Mn. The traditional methods were mainly focused on the extractions of V and Cr by oxidation or reduction processes. In the present work, chlorination method was adopted to keep the valence state of each elements as original state. In order to speed up the diffusion of elements and reduce volatility of molten salt, microwave heating has been examined in the current paper. The results indicated that it only took 30 min to chlorinate V-slag at 800 ?C, and the chlorination ratios of V, Cr, Mn, Fe and Ti could reach to 82.67%, 75.82%, 92.96%, 91.66% and 63.14%, respectively. Compared with the results by conventional heating for 8 h, this extraction rate by microwave heating shows greater advantages. In addition, microwave heating can reduce effectively volatilization of AlCl3 by shortening the reaction time. The volatilization ratio of AlCl3 in this microwave heating was 3.92% instead of 8.97% in conventional heating (1h). The mechanism of efficient chlorination can be summarized as the enhancement of ions diffusion process and enhanced chemical reaction due to local high temperature.

scholarly journals A Green Synthesis of a Novel Calix[4]Resorcinarene from 7-Hydroxycitronellal Using Microwave Irradiation

2018 ◽  
Vol 18 (1) ◽  
pp. 53
Author(s):  
Ratnaningsih Eko Sardjono ◽  
Iqbal Musthapa ◽  
Iis Rosliana ◽  
Fitri Khoerunnisa ◽  
Galuh Yuliani
Keyword(s):  
Energy Consumption ◽  
Reaction Time ◽  
Microwave Irradiation ◽  
Irradiation Time ◽  
Microwave Oven ◽  
Conventional Heating ◽  
Heating Method ◽  
Microwave Assisted ◽  
Domestic Microwave Oven ◽  
Waste Production

A new versatile macromolecule cyclic C-3,7-dimethyl-7-hydroxycalix[4]resorcinarene (CDHHK4R) has been synthesized from a fragrance agent, 7-hydroxycitronellal, via microwave irradiation. The reaction utilized a domestic microwave oven at various irradiation time and power to yield an optimum condition. As a comparison, the conventional heating method was also employed for the synthesis of the same calix[4]resorcinarene. Compared to the conventional method, microwave-assisted reaction effectively reduced the reaction time, the amount of energy consumption and the waste production. It is found that the synthesis of CDHHK4R by microwave irradiation yielded 77.55% of product, higher than by conventional heating which was only 62.17%.

THE EFFECT OF CONVENTIONAL AND MICROWAVE HEATING TECHNIQUES ON TRANSESTERIFICATION OF WASTE COOKING OIL TO BIODIESEL

2016 ◽  
Vol 78 (8-3) ◽  
Author(s):  
Mohd Johari Kamaruddin ◽  
Nurulsurusiah Mohamad ◽  
Umi Aisah Asli ◽  
Muhammad Abbas Ahmad Zaini ◽  
Kamarizan Kidam ◽  
...  
Keyword(s):  
Microwave Heating ◽  
Processing Parameters ◽  
Waste Cooking Oil ◽  
Green Technology ◽  
Conventional Heating ◽  
Molar Ratio ◽  
Catalyst Loading ◽  
Thermal Heating ◽  
Microwave Assisted ◽  
Cooking Oil

This research is focused on the effect of processing parameters such as molar ratio of sample to solvent (1:3-1:15), catalyst loading (0.5-2.5 wt %), temperature (40-80 °C) and time of reaction (5-180 min) on the transesterification yield of waste cooking oil (WCO) in conventional thermal heating and microwave heating techniques. The analysis carried out revealed that the microwave assisted transesterification produced a comparable yield to conventional heating transesterification with ~5 times faster in heating up the reaction mixture to a reaction temperature and reduced ~90% of the reaction time required. This study concludes that microwave assisted transesterification, which is a green technology, may have great potential in reducing the processing time compared to conventional thermal heating transesterification.

scholarly journals Intensification and optimization of biodiesel production using microwave-assisted acid-organo catalyzed transesterification process

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Moina Athar ◽  
Sadaf Zaidi ◽  
Saeikh Zaffar Hassan
Keyword(s):  
Reaction Time ◽  
Organic Acid ◽  
Microwave Heating ◽  
Low Cost ◽  
Acid Catalyst ◽  
Operating Conditions ◽  
Biodiesel Production ◽  
Conventional Heating ◽  
Molar Ratio ◽  
Inorganic Acid

AbstractTo produce biodiesel cost-effective, low-cost, high free fatty acid (FFA) oil feedstock is desirable. But high FFA creates difficulty during the base-catalyzed transesterification process by yield loss due to the formation of soap. However, these problems are overcome by the use of an acid catalyst. The acid catalysts can directly convert both triglycerides and FFAs into biodiesel without the formation of soaps or emulsions. The shortcomings of mostly used inorganic acids are that they work well for esterification of FFA present in low-cost oil, but their kinetics for transesterification of triglycerides present in oils is considerably slower. Corrosion of equipment is another major problem associated with an inorganic acid catalyst. The usage of an organic acid catalyst of the alkyl benzene sulfonic type, like 4-dodecyl benzene sulfonic acid (DBSA) minimizes these disadvantages of inorganic acid-catalyzed transesterification. The aim of the present investigation was to reduce the reaction time of transesterification of triglycerides further by using microwaves as a heating source in the presence of DBSA catalyst to achieve higher conversions under mild operating conditions. To optimize the transesterification variables for the higher conversion of biodiesel, the response surface methodology was employed to design the experiment. By using the DBSA catalyst under microwave heating at a temperature of 76 °C, conversion close to 100% in only 30 min of reaction time was obtained using a 0.09 molar ratio of catalyst to oil and 9.0 molar ratio of methanol to oil. A modified polynomial model was developed and was adequately fitted with the experimental data and could be used for understanding the effect of various process parameters. The catalyst to oil molar ratio and reaction temperature created a stronger effect on the biodiesel production than that exhibited by the methanol to oil molar ratio. It was observed that the microwave heating process outperformed conventional heating, providing a rapid, easy method for biodiesel synthesis from triglycerides in the presence of DBSA, an organic acid catalyst. The produced biodiesel was of good quality, as all the properties were within the prescribed limits of the ASTM D6751 standard.

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