108-50-9Relevant articles and documents
The effects of thermal treatment of ZnO–ZnCr2O4 catalyst on the particle size and product selectivity in dehydrocyclization of crude glycerol and ethylenediamine
Sarkari, Reema,Krishna, Vankudoth,Sudhakar, Medak,Rao, Tumula Venkateshwar,Padmasri, Aytam Hari,Srinivas, Darbha,Venugopal, Akula
, (2016)
The ZnO–ZnCr2O4 (Zn–Cr–O) sample obtained by decomposition of Zn-Cr hydrotalcite precursor was subjected to the thermal treatment at different temperatures and the physico-chemical properties of the Zn–Cr–O system were compared with
Vapor phase phototransposition chemistry of dimethylpyrazines and dimethylpyrimidines
Pavlik, James W.,Vongakorn, Tharinee,Kebede, Naod
, p. 216 - 228 (2017)
Based on their phototransposition chemistry, the three dimethylpyrazines and four dimethylpyrimidines can be arranged into two groups. 2,5-Dimethylpyrazine, 2,5-dimethylpyrimidine, and 4,6-dimethylpyrimidine constitute a photochemical triad. Irradiation of any one member of the triad in the vapor phase results in the formation of the other two members. The other four isomers, 2,6-dimethylpyrazine, 2,3-dimethylpyrazine, 2,4- dimethylpyrimidine, and 4,5-dimethylpyrimidine constitute a photochemical tetrad. Irradiation of any one member results in the formation of the other three. In addition, 2,4-dimethylpyrimidine and 2,6-dimethylpyrazine also photoisomerize to 3,6-dimethylpyridazine. Irradiation of the last in the vapor state resulted in the four members of the tetrad.
Synthesis of pyrazinyl compounds from glycerol and 1,2-propanediamine over Cu-TiO2 catalysts supported on γ-Al2O3
Li, Xue,Xu, Cheng-Hua,Liu, Chuan-Qi,Chen, Yu,Liu, Jian-Ying
, p. 751 - 754 (2013)
Cu-TiO2 catalysts supported on γ-Al2O 3 are prepared and used in glycerol cyclization with 1,2-propanediamine to produce pyrazinyl compounds including 6-hydroxymethyl-2- methylpyrazine, 5-hydroxymethyl-2-methylpyrazine, 2,6-dimethylpyrazine and 2,5-dimethylpyrazine in a fixed-bed system. It is found that glycerol cylclization with 1,2-propanediamine gave a high total yield of pyrazinyl compounds (>80%) over Cu-TiO2/γ-Al2O3 catalyst, and cyclization was through the reactions between activated 1,2-propanediamine and the intermediates from glycerol dehydration and oxidation. In addition, the regioselectivity of the pyrazinyl compounds was mainly controlled by the steric hindrance of the substrates during the cyclization process.
EFFECT OF TIME AND TEMPERATURE ON THE PREPARATION OF PYRAZINES IN MODEL REACTIONS OF THE SYNTHESIS OF AROMA-FORMING SUBSTANCES
Misharina, T. A.,Golovnya, R. V.,Yakovleva, V. N.
, p. 1258 - 1263 (1992)
The qualitative and quantitative compositions of pyrazines that form in model glucose-ammonia and glucose-ammonia-leucine reactions in a glycerol medium were studied.Reaction conditions were found that ensure the synthesis of 23 alkylpyrazines in total concentration ca. 6 g/kg.The obtained mixture of pyrazines is promising for use in the development of food aroma-forming substances.Keywords: pyrazines, Maillard reaction, capillary gas chromatography.
Regioselective Synthesis of Alkylpyrazines
Buechi, George,Galindo, Jose
, p. 2605 - 2606 (1991)
A new, regioselective synthesis of alkylpyrazines begins with condensation of α-oximido carbonyl compounds with allylamines.The resulting imines are isomerized in the presence of potassium tert-butoxide to the corresponding 1-hydroxy-1,4-diazahexatrienes.Thermal electrocyclization-aromatization to pyrazines is best performed after O-acylation of the oximes with methyl chloroformate.
Mechanisms of Formation of Alkylpyrazines in the Maillard Reaction
Amrani-Hemaimi, Miriam,Cerny, Christoph,Fay, Laurent B.
, p. 2818 - 2822 (1995)
The formation of alkylpyrazines was investigated in the reaction of glucose and fructose with -alanine and glycine.The reaction systems were heated for 7 min at 180 deg C.GC-MS and GC-MS/MS data were used to determine the rate of incorporati
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.
Acceptorless Dehydrogenative Coupling Using Ammonia: Direct Synthesis of N-Heteroaromatics from Diols Catalyzed by Ruthenium
Daw, Prosenjit,Ben-David, Yehoshoa,Milstein, David
supporting information, p. 11931 - 11934 (2018/09/27)
The synthesis of N-heteroaromatic compounds via an acceptorless dehydrogenative coupling process involving direct use of ammonia as the nitrogen source was explored. We report the synthesis of pyrazine derivatives from 1,2-diols and the synthesis of N-substituted pyrroles by a multicomponent dehydrogenative coupling of 1,4-diols and primary alcohols with ammonia. The acridine-based Ru-pincer complex 1 is an effective catalyst for these transformations, in which the acridine backbone is converted to an anionic dearomatized PNP-pincer ligand framework.
CuCr2O4 derived by the sol-gel method as a highly active and selective catalyst for the conversion of glycerol to 2,6-dimethylpyrazine: A benign and eco-friendly process
Vankudoth, Krishna,Gutta, Naresh,Velisoju, Vijay Kumar,Mutyala, Suresh,Aytam, Hari Padmasri,Akula, Venugopal
, p. 3399 - 3407 (2017/08/16)
Vapour phase dehydrocyclization of crude glycerol in conjunction with 1,2-propanediamine (1,2-PDA) was examined over CuCr2O4 obtained by different preparation methods. A high proportion of copper species interacted with Cr2O3 in CuCr2O4 derived from the sol-gel route with a low ratio of Cu2+/Cu0 demonstrating higher dehydrocyclization activity and 2,6-dimethylpyrazine (2,6-DMP) selectivity. X-ray photoelectron spectroscopy analysis of the reduced CuCr2O4 revealed a lower fraction of ionic Cu and a high percentage of metallic Cu in the near surface region. The HCOOH and pyridine adsorbed DRIFT spectra of CuCr2O4 revealed that strong basic and moderate Lewis acid sites are responsible for the selective formation of 2,6-dimethylpyrazine which is consistent with the catalyst poisoning studies on CuCr2O4 co-feeding with pyridine as both Br?nsted and Lewis acid site blocker and 2,6-lutidine as a selective Br?nsted acid site blocker during the dehydrocyclization reaction. The presence of isolated CuO and Cr2O3 species led to a high selectivity for 2,6-dimethylpiperazine. The high intrinsic activity of CuCrsol-gel was also concomitant with the Cu metal surface areas of the catalysts. The fresh, reduced and some of the used catalysts are characterized by BET-surface area, powder XRD, FTIR, XPS, TEM, H2-TPR, TPD of NH3, pyridine, 2,6-dimethylpyridine and HCOOH adsorbed DRIFT spectroscopy.
The role of Lewis acid-base pair sites in ZnO-ZnCr2O4 catalysts for cyclization: Via dehydrogenative condensation of crude glycerol and 1,2-propanediamine for the synthesis of 2,6-dimethylpyrazine
Vankudoth, Krishna,Padmasri, A. Hari,Sarkari, Reema,Velisoju, Vijay Kumar,Gutta, Naresh,Sathu, Naveen Kumar,Rohita,Akula, Venugopal
supporting information, p. 9875 - 9883 (2017/09/18)
Nano-crystalline mixed oxides of ZnO-ZnCr2O4 (ZC) derived from Zn-Cr-HT precursors were examined for the vapor phase dehydrogenative condensation of crude glycerol and 1,2-propanediamine (1,2-PDA) to synthesize 2,6-dimethylpyrazine (1,2-DMP). The nature of the surface active sites is illustrated by BET-SA, XRD, ESR, H2-TPR, TPD of NH3, TEM, XPS, and pyridine and HCOOH adsorbed DRIFT spectroscopy. The role of acid-base sites in the product distribution is discussed using the catalytic activity data under a kinetic regime. The in situ IR studies revealed that the dehydration of glycerol occurs on weak Lewis acid sites and dehydrogenation takes place on strong basic sites on the catalyst surface. A relationship between surface acid-base strength and the 2,6-DMP rate is established.
