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All total 48 Articles be foundCatalytic Synthesis Of Aziridine From 1,2-Diaminoethane
Anderson, A. A.,Simonyan, S. P.,Shimanskaya, M. V.
, p. 1134 - 1141 (1993)
The contact conversion of 1,2-diaminoethane over a tungsten trioxide catalyst at 240-580 deg C has been studied by an impulse chromatographic method.The basic reaction path under these conditions is unimolecular deaminocyclization to give aziridine (31-35percent).Piperazine and triethylenediamine, products of bi- and trimolecular deaminocyclization, are present as products.The deamination process is accompanied by coupled dehydrogenation and hydrogenolysis reactions.Addition of the acid anhydrides SiO2, P2O5 and B2O3 to the catalyst increases its activity but has onlyanegligible affect on the activation energy of the process.
Effective utilization of glycerol for the synthesis of 2-methylpyrazine over ZnO-ZnCr2O4 catalyst
Venugopal,Sarkari,Naveen Kumar,Kotesh Kumar,Syed John,Krishna Reddy,Hari Padmasri
, p. 387 - 393 (2014)
Bioglycerol an inevitable by-product in the production of biodiesel was effectively utilized for the synthesis of 2-methylpyrazine (2-MP) by vapour phase dehydrocyclization with ethylenediamine over ZnO-ZnCr2O 4(Zn-Cr-O) mixed oxides
Volatile Compounds Generated from Thermal Reaction of Methionine and Methionine Sulfoxide with or without Glucose
Yu, Tung-Hsi,Ho, Chi-Tang
, p. 1641 - 1646 (1995)
Methionine and methionine sulfoxide were mixed with or without glucose in distilled water, individually.These solutions were heated in closed sample cylinders at 180 deg C for 1 h.The volatile compounds generated were extracted using methylene chloride and analyzed by GC and GC-MS.Pyrazine compounds, especially 2,5-dimethyl-, 2-ethyl-5-methyl-, trimethyl-, and methylpyrazines were the predominant compounds among those generated from thermal interactions of glucose and methionine or methionine sulfoxide.The formation of methional or those compounds derived for methional was found to be more favorable from the thermal degradation of methionine, whereas the formation of dimethyl polysulfides, especially dimethyl disulfide and dimethyl trisulfide, was found to be more favorable from the thermal degradation of methionine sulfoxide.Glucose was found to have a catalytic effect on the formation of volatile compounds from the thermal degradation of methionine or methionine sulfoxide.Keywords: Methionine; methionine sulfoxide; methional; methyl sulfides; volatiles
Catalytic synthesis of 2-methylpyrazine over Cr-promoted copper based catalyst via a cyclo-dehydrogenation reaction route
Jing, Fangli,Zhang, Yuanyuan,Luo, Shizhong,Chu, Wei,Zhang, Hui,Shi, Xinyu
, p. 621 - 630 (2010)
The cyclo-dehydrogenation of ethylene diamine and propylene glycol to 2-methylpyrazine was performed under the atmospheric conditions at 380°C. The Cr-promoted Cu-Zn/Al 2O 3 catalysts were prepared by impregnation method and characterized by ICP-AES, N 2 adsorption/desorption, XRD, XPS, N 2O chemisorption, TPR and NH3-TPD techniques. The amorphous chromium species existing in Cu-Zn-Cr/Al 2O 3 catalyst enhanced the dispersion of active component Cu, promoted the reduction of catalyst. Furthermore, the catalytic performance was significantly improved. The acidity of the catalyst played an important role in increasing the 2-MP selectivity. To optimize the reaction parameters, influences of different chromium content, reaction temperature, liquid hourly space velocity (LHSV), reactants molar ratio and time on stream on the product pattern were studied. The results demonstrated that addition of chromium promoter revealed satisfying catalytic activity, stability and selectivity of 2-methylpyrazine. Indian Academy of Sciences.
Degradation Products Fromed from Glucosamine in Water
Shu, Chi-Kuen
, p. 1129 - 1131 (1998)
An aqueous solution of glucosamine hydrochloride was heated to 150 °C for 5 min under different pH conditions. The reaction product mixture obtained was analyzed by GC/MS. It was found that the major products formed were furfurals, especially at pH = 4 and 7. At pH = 8.5, additional flavor components were generated, including pyrazines, 3-hydroxypyridines, pyrrole-2-carboxaldehyde, furans, acetol, and several other compounds. Of the components identified, it is worthwhile to note the formation of pyrazine and methylpyrazine as major components at pH = 8.5. It is proposed that a retro-aldol condensation plays an important role in the formation of the intermediates, α-aminoacetaldehyde (I) and α-amino propanal (II). As a result, self-condensation of I generates pyrazine and combination of I and II generates methylpyrazine. In addition, it is also interesting to note the formation of 3-hydroxypyridines and pyrrole-2-carboxaldehyde. It is suggested that both groups of compounds are derived from furfurals. As the ammonia is liberated from glucosamine, it initiates the ring-opening of furfurals to form 5-amino-2-keto-3-pentenals. Intramolecular condensations of these intermediates between the amino group and the carbonyl groups lead to the formation of 3-hydroxypyridines and pyrrole-2-carboxalhyde.
Vapor phase synthesis of methylpyrazine using aqueous glycerol and ethylenediamine over ZnCr2O4 catalyst: Elucidation of reaction mechanism
Sarkari, Reema,Anjaneyulu, Chatla,Krishna, Vankudoth,Kishore, Ramineni,Sudhakar, Medak,Venugopal, Akula
, p. 1067 - 1070 (2011)
A novel method has been developed for the synthesis of methylpyrazine (MP) by using aqueous glycerol and ethylenediamine (EDA) over Zn-Cr catalyst derived from hydrotalcite precursors. The X-ray diffraction analysis of the oven-dried Zn-Cr samples synthesized at various pH ranging from 7 to 11 showed hydrotalcite phase whereas the calcined catalysts displayed ZnO and ZnCr2O 4 phases. The cyclisation activity of Zn-Cr catalyst prepared at pH ～ 9 demonstrated 99.4% conversion of EDA and 94% of glycerol with ～ 72% selectivity to MP at a reaction temperature of 400 °C. This process demonstrates direct utilization of bio-glycerol for the synthesis of MP.
SYNTHESIS OF NITROGEN CONTAINING HETEROCYCLES OVER COPPER CHROMITE
Meksh, P.A.,Anderson, A.A.,Shimanska, M.
, p. 822 - 828 (1994)
The reactions of 1,2-diaminopropane, 1-amino-2-propanol, 1-amino-2-ethanol, and N-(β-aminoethyl)-1,2-diaminoethane in the gas phase over copper chromite have been investigated with the objective of synthesising nitrogen containing heterocycles.At 240-360
Synthesis of 2-methylpyrazine on ternary oxide catalysts
Kagarlitskii,Krichevskii,Balpanov
, p. 1093 - 1095 (2005)
Synthesis of 2-methylpyrazine by cyclocondensation of ethylenediamine with 1,2-propylene glycol in the presence of zinc-molybdenum-chromium catalysts was studied.
Influence of acid-base sites on ZnO-ZnCr2O4 catalyst during dehydrocyclization of aqueous glycerol and ethylenediamine for the synthesis of 2-methylpyrazine: Kinetic and mechanism studies
Venugopal, Akula,Sarkari, Reema,Anjaneyulu, Chatla,Krishna, Vankudoth,Kumar, Mandari Kotesh,Narender, Nama,Padmasri, Aytam Hari
, p. 398 - 409 (2014)
The physicochemical characteristics of ZnO-ZnCr2O4 (Zn-Cr-O) mixed oxides were determined by adsorption and spectroscopic methods. The catalytic activities of Zn-Cr-O was investigated for dehydrocyclization of ethylenediamine and aqu
Glycerol catalytic cyclocondensation with ethanediamine to pyrazinyl compounds over the modified SiO2-Al2O3
Liu, Chuanqi,Xu, Chenghua,Xia, Tongwei,Guo, Yan,Liu, Jianying
, p. 377 - 382 (2012)
The Fe, Zn, and Mn-modified SiO2-Al2O3 catalysts for the glycerol vapor-phase cyclocondensation with ethanediamine (ED) to 2-pyrazinemethanol (2-PMol) and 2-methylpyrazine (2-MP) in a fixed-bed system were prepared by coprecipitation and characterized by N2 adsorption-desorption, X-ray powder diffraction, and NH3 temperature-programmed desorption (NH3-TPD) in the present work. The results showed that the Mn-modified SiO2-Al2O3 catalyst with a SiO2/Al2O3 molar ratio 15.84 and 6% Mn gave the highest catalytic activity for formation of 2-PMol (53.1%) and 2-MP (42.9%). Mn species could cause the modulation of the acidic species of catalysts, improving the glycerol cyclocondensation with ED to 2-PMol, and also acted as the catalytic centers for the hydrodehydration of 2-PMol to 2-MP. However, too many strong acidic sites could lead to ED self-cyclocondensation to form a by-product pyrazine. The optimum temperature was tested to be 380°C for the cyclocondensation over a 6%Mn-SiO2-Al2O 3 catalyst.
Comparison of pyrazines formation in methionine/glucose and corresponding Amadori rearrangement product model
Cui, Heping,Deng, Shibin,Hayat, Khizar,Ho, Chi-Tang,Zhai, Yun,Zhang, Qiang,Zhang, Xiaoming
, (2022/03/07)
The generation of pyrazines in a binary methionine/glucose (Met/Glc) mixture and corresponding methionine/glucose-derived Amadori rearrangement product (MG-ARP) was studied. Quantitative analyses of pyrazines and methional revealed that MG-ARP generated more methional compared to Met/Glc, whereas lower content and fewer species of pyrazines were observed in the MG-ARP model. Comparing the availability of α-dicarbonyl compounds generated from the Met/Glc model, methylglyoxal (MGO) was a considerably effective α-dicarbonyl compound for the formation of pyrazines during MG-ARP degradation, but glyoxal (GO) produced from MG-ARP did not effectively participate in the corresponding formation of pyrazines due to the asynchrony on the formation of GO and recovered Met. Diacetyl (DA) content was not high enough to form corresponding pyrazines in the MG-ARP model. The insufficient interaction of precursors and rapid drops in pH limited the formation of pyrazines during MG-ARP degradation. Increasing reaction temperature could reduce the negative inhibitory effect by promoting the content of precursors.
Application of a reusable Co-based nanocatalyst in alcohol dehydrogenative coupling strategy: Synthesis of quinoxaline and imine scaffolds
Panja, Dibyajyoti,Paul, Bhaskar,Balasubramaniam, Bhuvaneshwari,Gupta, Raju K.,Kundu, Sabuj
, (2020/01/21)
A nitrogen doped carbon supported cobalt catalyzed efficient synthesis of imines and quinoxaline motifs is reported. Co(OAc)2-Phen/Carbon-800 (Co-phen/C-800) showed the superior reactivity compared to other materials prepared at different temperature, in the synthesis of quinoxalines by the coupling between diamines and diols. Moreover, applying the transfer hydrogenation and acceptorless dehydrogenative coupling strategy, imines and quinoxaline derivatives were synthesized from the nitro compounds. The practical applicability of this protocol was demonstrated by the gram-scale synthesis and the reusability of the catalyst upto 8th cycle. Furthermore, several kinetic experiments were carried out to realize the probable mechanism.
