• Title/Summary/Keyword: Microwave-assisted synthesis

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Microwave-Assisted One-Pot Synthesis of Octahydroquinazolinone Derivatives Catalyzed by Thiamine Hydrochloride Under Solvent-free Condition

  • Badadhe, Pravin V.;Chate, Asha V.;Hingane, Dattatraya G.;Mahajan, Pravin S.;Chavhan, Namdev M.;Gill, Charansingh H.
    • Journal of the Korean Chemical Society
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    • v.55 no.6
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    • pp.936-939
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    • 2011
  • Thiamine hydrochloride (VB1) has been used as an acid catalyst in organic synthesis. One pot three component Biginelli condensation of dimedone, urea/thiourea and substituted aromatic aldehydes catalyzed by 10 mol % of thiamine hydrochloride (VB1) in solvent free condition under microwave irradiation in good to excellent yields has been investigated. Utilization of microwave irradiation, simple reaction conditions, short reaction time, ease of product isolation, and purification makes this manipulation very interesting from an economic and environmental perspective.

Microwave Assisted Synthesis of 1,3,4-Oxadiazole/Thiohydantoin Hybrid Derivatives via Dehydrative Cycliztion of Semicarbazide

  • Yang, Seung-Ju;Lee, Jae-Min;Lee, Gee-Hyung;Kim, NaYeon;Kim, Yong-Sang;Gong, Young-Dae
    • Bulletin of the Korean Chemical Society
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    • v.35 no.12
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    • pp.3609-3617
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    • 2014
  • A series of compounds containing both 1,3,4-oxadiazole and thiohydantoin were synthesized as a promising scaffold for application in medicinal chemistry. The key step of the synthesis is a microwave-assisted cyclization of semicarbazides possessing a thiohydantoin moiety at one of the acyl termini using $POCl_3$ as a dehydrating reagent. A wide range of semicarbazides were prepared through the substitution of hydrazides with an N-acylated thiohydantoin derived from the cyclization of the corresponding isothiocyanate with an amino acid and subsequent N-acylation of the resultant thiohydrantion. Consequently, the 58 number of 1,3,4-oxadiazole derivatives having a thiohydantoin substituent were prepared in good overall yields.

Microwave Assisted Synthesis of Graphene-Bi2MoO6 Nanocomposite as Sono-Photocatalyst

  • Tang, Jia-Yao;Zhu, Lei;Fan, Jia-Yi;Sun, Chen;Oh, Won-Chun
    • Korean Journal of Materials Research
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    • v.32 no.1
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    • pp.1-8
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    • 2022
  • In this investigation, Bi2MoO6 deposited graphene nanocomposite (BMG) was synthesized using a simple microwave assisted hydrothermal synthesis method. The synthesized BMG nanocomposite was characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy with energy dispersive X-ray analysis, and photocurrent analysis. The study revealed that the catalysts prepared have high crystalline nature, enhanced light responsive property, high catalytic activity, and good stability. XRD results of BMG composite exhibit a koechlinite phase of Bi2MoO6. The surface property is shown by SEM and TEM, which confirmed a homogenous composition in the bulk particles of Bi2MoO6 and nanosheets of graphene. The catalytic behavior was investigated by the decomposition of Rhodamine B as a standard dye. The results exhibit excellent yields of product derivatives at mild conditions under ultrasonic/visible light-medium. Approximately 1.6-times-enhanced sono-photocatalytic activity was observed by introduction of Bi2MoO6 on graphene nanosheet compared with control sample P25 during 50 min test.

Synthesis and Study of Pt/MWCNTs Catalysts by Using Microwave Assisted Polyol Method for PEM Fuel Cells (마이크로파-폴리올법을 이용한 고분자 전해질 연료전지용 Pt/MWCNTs 촉매의 제조 및 이의 특성분석)

  • Lee, Tae Kyu;Hur, Seung Hyun
    • Journal of the Korean Electrochemical Society
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    • v.15 no.4
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    • pp.264-269
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    • 2012
  • In this study, highly loaded(50 wt%) and very stable Pt/MWCNT catalysts for Polymer Electrolyte Membrane Fuel Cells(PEMFCs) are synthesized in short time scale by microwave assisted polyol method with different microwave irradiation time. The XRD and TEM results show that the Pt size becomes bigger as the microwave irradiation time increases. The mean Pt sizes of fabricated catalysts are 4.1, 4.9 and 8.5 nm when the microwave are irradiated for 10, 20 and 30 min, respectively. When compared with Pt catalyst made by conventional polyol method, it shows better long term durability due to the better Pt dispersion on the MWCNT surface.

Microwave Assisted Rapid Synthesis of Novel Optically Active Poly(amide-imide)s Based on N-Trimellitylimido-L-Leucine Diacid Chloride and Hydantoin Derivatives

  • Faghihi, Khalil
    • Macromolecular Research
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    • v.12 no.3
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    • pp.258-262
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    • 2004
  • We have developed facile and rapid polycondensation reactions of N-trimellitylimido-L-leucine diacid chloride 1 with eight different derivatives of hydantoin compounds 2a-h, in the presence of a small amount of a polar organic medium, such as Ο-cresol, by using a domestic microwave oven. The polycondensation reactions proceeded rapidly-they were complete within 7-9 min-to produce a series of novel optically active poly(amide-imide)s (3a-h) in high yield with inherent viscosities of 0.33-0.51 dL/g. We characterized the resulting poly(amide-imide)s by elemental analysis, thermal gravimetric analysis (DSC, TGA, and DTG), and FTIR spectroscopy, and by measuring their viscosities, specific rotations, and solubilities. All of the polymers were soluble at room temperature in polar solvents such as N ,N-dimethylacetamide, N,N-dimethylformamide, dimethylsulfoxide, tetrahydrofuran, and N-methyl-2-pyrrolidone.

Comparative Study on Convective and Microwave-Assisted Heating of Zeolite-Monoethanolamine Adsorbent Impregnation Process for CO2 Adsorption

  • Oktavian, Rama;Poerwadi, Bambang;Pardede, Kristian;Aulia, Zuh Rotul
    • Korean Chemical Engineering Research
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    • v.59 no.2
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    • pp.260-268
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    • 2021
  • Adsorption is the most promising technology used to adsorb CO2 to reduce its concentration in the atmosphere due to its functional effectiveness. Various porous materials have been extensively synthesized to boost CO2 adsorption efficiency, for example, zeolite. Here, we report the synthesis process of zeolite adsorbent impregnated with amine, combining the benefit of these two substances. We compared conventional heating with microwave-assisted heating by varying concentrations of monoethanolamine in methanol (10% v/v and 40% v/v) as a liquid solution. The results showed that monoethanolamine impregnation helps significantly increase adsorption capacity, where adsorption occurs as a physisorption and not as chemisorption due to the adsorbent's steric hindrance effect. The highest adsorption capacity of 0.3649 mmol CO2 / gram adsorbent was reached by microwave exposure for 10 minutes. This work also reveals that a decrease in CO2 adsorption capacity was observed at a longer exposure period, and it reached a constant 40-minute adsorption rate. Impregnating activated zeolite with 40% monoethanolamine for 10 minutes in addition to microwave exposure (0.8973 mmol CO2 / gram adsorbent) is the maximum adsorption ability achieved.

Efficient Microwave-assisted Deoxydehydration (DODH) Reactions: Synthesis of Adipic Acid from Galactose (마이크로웨이브를 이용한 효율적인 탈산소탈수(DODH) 반응: 갈락토스 유래 아디픽산의 합성)

  • Shin, Nara;Kwon, Sohyun;Kim, Young Gyu
    • Applied Chemistry for Engineering
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    • v.28 no.2
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    • pp.165-170
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    • 2017
  • An efficient synthetic process for bio-based adipic acid, a monomer for nylon 66, was developed from galactose. Galactaric acid, prepared from a mild oxidation of galactose using a Pt catalyst, was successfully converted to muconate, a key intermediate for adipic acid, by an efficient microwave-assisted DODH (deoxydehydration) reaction. The high efficiency of the microwave-assisted reaction greatly reduced the overall reaction time to 30 min. and resulted in an excellent yield of 97% of muconate. The catalytic hydrogenation of muconate followed by the acidic hydrolysis successfully produced the desired adipic acid in high purity after recrystallization.

Microwave Assisted One-pot Synthesis of Novel α-Aminophosphonates and heir Biological Activity

  • Rao, Alahari Janardhan;Rao, Pasupuleti Visweswara;Rao, Valsani Koteswara;Mohan, Challamchalla;Raju, Chamarthi Naga;Reddy, Cirandur Suresh
    • Bulletin of the Korean Chemical Society
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    • v.31 no.7
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    • pp.1863-1868
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    • 2010
  • A simple and efficient synthesis of various $\alpha$-aminophosphonates (3a-l) by the reaction of substituted aromatic/heterocyclic aldehydes, 2-amino-6-methoxy-benzothiazole and dibutyl/diphenyl phosphites under microwave irradiation without catalyst was accomplished. The phosphonates were characterized by elemental analysis, IR, $^1H$, $^{13}C$- and $^{31}PNMR$ spectra. They showed promising antimicrobial, anti-oxidant activities depending on the nature of bioactive groups at the $\alpha$-carbon.

Microwave-Assisted Synthesis of 3-Styrylchromones in Alkaline Ionic Liquid

  • Shelke, Kiran F.;Sapkal, Suryakant B.;Shitole, Nana V.;Shingate, Bapurao B.;Shingare, Murlidhar S.
    • Bulletin of the Korean Chemical Society
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    • v.30 no.12
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    • pp.2883-2886
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    • 2009
  • A simple, highly efficient and environmentally benign method for the synthesis of 3-styrylchromones from 3-formylchromones and 4-nitrophenylacetic acid/4-nitrotolune in the presence of catalytic amount of basic ionic liquid 1-butyl-3-methylimidazolium hydroxide [(bmim)OH] carried out under the influence of microwave irradiation. This method gives remarkable advantages such as, short reaction times, simple work-up procedure and moderate to good yields. The ionic liquid was successfully reused for four cycles without significant loss of activity.

Base Catalysed Pyrimidine Synthesis Using Microwave

  • Kidwai, M.;Rastogi, S.;Saxena, S.
    • Bulletin of the Korean Chemical Society
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    • v.24 no.11
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    • pp.1575-1578
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    • 2003
  • An environmentally benign approach for the synthesis of 2-substituted-4,6-diaryl pyrimidines using inorganic solid supports for its catalytic role as well as an energy transfer medium is described. The methodology eliminates the usage of solvent during the reaction. The reaction time is brought down from hours to minutes along with yield enhancement. The rate enhancement and high yield is attributed to the coupling of solvent free conditions with microwaves. Further, the role of base is studied in the reaction and it is concluded that microwave assisted basic alumina catalysed reaction is the best in terms of catalysis as well as reaction time and yield.