- Thermal characterization of the solid state and raw material fluconazole by thermal analysis and pyrolysis coupled to GC/MS
-
This article had studied the thermal characterization of the raw material and different fluconazole crystals, obtained through recrystallization with different solvents using thermoanalytical techniques (TG, DTA, DSC-50, DSC Photovisual, DSC-60) and Pyr-GC/MS. The results confirmed that the fluconazole volatilizes without decomposition until 250 °C. Pyr-GC/MS showed hexachlorobenzene like impurities in fluconazole raw material.
- Moura, Elisana Afonso,Correia, Lidiane Pinto,Pinto, Marcia Ferraz,Procopio, Jose Valdilanio Virgulino,De Souza, Fabio Santos,MacEdo, Rui Oliveira
-
-
Read Online
- Acceptorless Dehydrogenative Coupling Using Ammonia: Direct Synthesis of N-Heteroaromatics from Diols Catalyzed by Ruthenium
-
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.
- Daw, Prosenjit,Ben-David, Yehoshoa,Milstein, David
-
supporting information
p. 11931 - 11934
(2018/09/27)
-
- Synthesis of Pyrazines and Quinoxalines via Acceptorless Dehydrogenative Coupling Routes Catalyzed by Manganese Pincer Complexes
-
Base-metal catalyzed dehydrogenative self-coupling of 2-amino alcohols to selectively form functionalized 2,5-substituted pyrazine derivatives is presented. Also, 2-substituted quinoxaline derivatives are synthesized by dehydrogenative coupling of 1,2-diaminobenzene and 1,2-diols. In both cases, water and hydrogen gas are formed as the sole byproducts. The reactions are catalyzed by acridine-based pincer complexes of earth-abundant manganese.
- Daw, Prosenjit,Kumar, Amit,Espinosa-Jalapa, Noel Angel,Diskin-Posner, Yael,Ben-David, Yehoshoa,Milstein, David
-
p. 7734 - 7741
(2018/08/03)
-
- Competing Knorr and Fischer-Fink pathways to pyrroles in neutral aqueous solution
-
A proposed chemical model for the prebiogenesis of tetrapyrrole macrocycles relies on the condensation of a 3-alkyl-substituted 2,4-diketone and an α-aminoketone to form a pyrrole equipped for subsequent self-condensation leading to porphyrinogens. The co
- Chandrashaker, Vanampally,Taniguchi, Masahiko,Ptaszek, Marcin,Lindsey, Jonathan S.
-
experimental part
p. 6957 - 6967
(2012/09/07)
-
- Impact of the N-terminal amino acid on the formation of pyrazines from peptides in maillard model systems
-
Only a minor part of Maillard reaction studies in the literature focused on the reaction between carbohydrates and peptides. Therefore, in continuation of a previous study in which the influence of the peptide C-terminal amino acid was investigated, this study focused on the influence of the peptide N-terminal amino acid on the production of pyrazines in model reactions of glucose, methylglyoxal, or glyoxal. Nine different dipeptides and three tripeptides were selected. It was shown that the structure of the N-terminal amino acid is determinative for the overall pyrazine production. Especially, the production of 2,5(6)-dimethylpyrazine and trimethylpyrazine was low in the case of proline, valine, or leucine at the N-terminus, whereas it was very high for glycine, alanine, or serine. In contrast to the alkyl-substituted pyrazines, unsubstituted pyrazine was always produced more in the case of experiments with free amino acids. It is clear that different mechanisms must be responsible for this observation. This study clearly illustrates the capability of peptides to produce flavor compounds such as pyrazines.
- Van Lancker, Fien,Adams, An,De Kimpe, Norbert
-
scheme or table
p. 4697 - 4708
(2012/08/27)
-
- The effect of pH on the formation of aroma compounds produced by heating a model system containing l-ascorbic acid with l-threonine/l-serine
-
The identification of aroma compounds, formed from the reactions of l-ascorbic acid with l-threonine/l-serine at five different pH values (5.00, 6.00, 7.00, 8.00, or 9.55) and 143 ± 2 °C for 2 h, was performed using a SPME-GC-MS technique, and further use
- Yu, Ai-Nong,Zhang, Ai-Dong
-
experimental part
p. 214 - 219
(2011/12/14)
-
- Supersonic jet studies of alkyl-substituted pyrazines and pyridines. Minimum energy conformations and torsional motion
-
Conformational reference for methyl-, ethyl-, propyl-, and isoproply-substituted pyrazines and pyridines are determined by mass resolved excitation spectroscopy (MRES) and MOPAC 5/PM3 semiempirical calculations. The results of these studies suggest that the conformational behavior of alkyl-substituted pyrazines and pyridines is different from that of alkyl-subtituted benzenes. Based on the experimental and semiempirical theoretical results reported herein and published ab initio calculations, this difference can be attributed to a stabilizing interaction between an α-hydrogen atom of alkyl subsituted and the adjacent lone pair nonbonding electrons on the ring nitrogen atom.
- Seeman, Jeffey I.,Paine III, John B.,Secor, Henry V.,Im, Hoong-Sun,Bernstein
-
p. 5269 - 5280
(2007/10/02)
-
- Process for preparing pyrazines from hydroxyamines
-
This invention relates to the reaction of hydroxyamines to form pyrazines by a process comprising reacting said hydroxyamine in the presence of a catalyst which may be a transition metal catalyst optionally containing an alkaline earth metal oxide, or alternatively the catalyst may be a rhodium, ruthenium or palladium-containing compound and a phosphine-containing compound.
- -
-
-
