- Photochemistry of the 1,4-Aliphatic Diketones
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The photochemistry of ketones with general formula RC(=O)CH2CH2C(=O)R', where R and R' represent the methyl, propyl, n-butyl, and isoamyl groups was investigated.The results obtained provide evidence of fast energy migration between the chromophores both in the singlet and triplet excited states.The rate energy migration can be estimated as 2e8 and 3e8 s-1 for the singlet and triplet states, respectively.
- Lissi, E. A.,Encinas, M. V.,Castaneda, F.,Olea, F. A.
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- Characterization of initial reaction intermediates in heated model systems of glucose, glutathione, and aliphatic aldehydes
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To understand the effect of lipid degradation on Maillard formation of meaty flavors, initial reaction intermediates in model systems of glucose–glutathione with hexanal, (E)-2-heptenal, or (E,E)-2,4-decadienal were identified by HPLC–MS and by NMR. Besides Amadori compounds, hemiacetals and thiazolidines via addition of sulfhydryl to carbonyl or to the conjugated olefinic bond were found. Concentrations of all intermediates increased with reaction time while degradation of the intermediates with a glutathione moiety helped formation of thiazolidines with cysteinylglycine. The unsaturated aldehydes (E)-2-heptenal and (E,E)-2,4-decadienal exhibited high reactivity against glucose for glutathione, yielding higher levels of intermediate compounds than from glucose. Heating prepared intermediates reversibly released the original aldehydes, which caused various compounds formed by retro-aldol, oxidation, etc. to react with H2S and NH3. Among them, formation pathways including 3-nonen-2-one, 2-hexanoylfuran, and six dialkylthiophenes (e.g., 2-ethyl-5-(1-methylbutyl)thiophene) were proposed for the first time.
- Wang, Tianze,Zhen, Dawei,Tan, Jia,Xie, Jianchun,Cheng, Jie,Zhao, Jian
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- Ex situ catalytic upgrading of lignocellulosic biomass components over vanadium contained H-MCM-41 catalysts
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H-V-MCM-41 catalysts containing 5, 10, and 30 wt% of vanadium were synthesized and applied to the ex situ catalytic pyrolysis (CP) of three polymeric components of lignocellulosic biomass for the first time. Characterization of the catalysts was performed using N2 adsorption-desorption, XRD, FT-IR, and NH3-TPD. The results of XRD analysis showed that 5 wt% and 10 wt% H-V-MCM-41 catalysts maintained the mesoporous structure, whereas the mesoporous structure was destroyed in 30 wt% H-V-MCM-41 with considerable amount of small V2O5 crystalline outside the framework. NH3-TPD showed that H-V-MCM-41 has mostly weak acid sites and that 10 wt% H-V-MCM-41 had the largest quantity of acid sites due to framework vanadium. In the case of CP of cellulose using Py-GC/MS, 10 wt% H-V-MCM-41 showed the highest catalytic activity for the production of valuable furanic compounds such as furfural because of the enhanced deoxygenation over the acid sites formed on framework vanadium. In the case of CP of xylan as well, 10 wt% H-V-MCM-41 led to the largest yield of mono-aromatics. The production of acetic acid was also promoted by H-V-MCM-41 catalysts. The CP of lignin over H-V-MCM-41 catalysts promoted substantially the production of important feedstock chemicals for the petrochemical industry: phenolics and mono-aromatics.
- Kim, Beom-Sik,Jeong, Chang Seok,Kim, Ji Man,Park, Su Bin,Park, Sung Hoon,Jeon, Jong-Ki,Jung, Sang-Chul,Kim, Sang Chai,Park, Young-Kwon
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p. 184 - 191
(2016/03/08)
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- Dinuclear iron complex-catalyzed cross-coupling of primary alkyl fluorides with aryl grignard reagents
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Iron-catalyzed cross-coupling of nonactivated primary alkyl fluorides with aryl Grignard reagents has been achieved by using the low-coordinate dinuclear iron complex [(IPr2Me2)Fe(μ2-NDipp) 2Fe(IPr2Me2)] as the catalyst. This iron-catalyzed C(sp3)-F bond arylation reaction is applicable to a variety of aryl Grignard reagents and primary alkyl fluorides. The product pattern suggests the involvement of a radical-type mechanism for its C-F bond scission step.
- Mo, Zhenbo,Zhang, Qiang,Deng, Liang
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p. 6518 - 6521
(2012/10/29)
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- Amino acid catalysis of 2-alkylfuran formation from lipid oxidation-derived α,β-unsaturated aldehydes
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The formation of 2-alkylfurans from the corresponding lipid-derived α,β-unsaturated aldehydes under dry-roasting conditions was investigated in detail. The addition of an amino acid to an α,β- unsaturated aldehyde drastically increased 2-alkylfuran formation. Peptides and proteins as well were able to catalyze 2-alkylfuran formation from the corresponding α,β-unsaturated aldehydes. Further investigation of 2-alkylfuran formation showed the need of oxidizing conditions and the involvement of radicals in the reaction. This way, the formation of 2-methylfuran from 2-pentenal, 2-ethylfuran from 2-hexenal, 2-propylfuran from 2-heptenal, 2-butylfuran from 2-octenal, 2-pentylfuran from 2-nonenal, and 2-hexylfuran from 2-decenal was shown. The impact of amino acids on 2-alkylfuran formation from lipid-derived α,β-unsaturated aldehydes represents an interesting example of the complex role of amino acids in the multitude of chemical reactions occurring during thermal processing of lipid-rich foods.
- Adams, An,Bouckaert, Capucine,Van Lancker, Fien,De Meulenaer, Bruno,De Kimpe, Norbert
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experimental part
p. 11058 - 11062
(2012/02/06)
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- Laccase-catalyzed stereoselective oxidative ring opening of 2,5-dialkylfurans into 2-ene-1,4-diones using air as an oxidant
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The laccase-catalyzed ring opening of 2,5-dimethylfuran using air as an oxidant stereoselectively yields (Z)- or (E)-3-hexene-2,5-dione depending on the mediator employed: with TEMPO the (Z)-3-hexene-2,5-dione is formed, while a combination of TEMPO and violuric acid gives (E)-3-hexene-2,5-dione. The (Z)-selective ring cleavage was extended to a variety of symmetrical and unsymmetrical 2,5-dialkylfurans. The Royal Society of Chemistry.
- Asta, Chimene,Conrad, Juergen,Mika, Sabine,Beifuss, Uwe
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supporting information; experimental part
p. 3066 - 3069
(2011/12/21)
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- (2E)-4-hydroxyalk-2-enals and 2-substituted furans as products of reactions of (2E)-4,4-dimethoxybut-2-enal with Grignard compounds
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Methods have been developed for the synthesis of (2E)-1,1-dimethoxyalk-2- en-4-ols and (2E)-4-hydroxyalk-2-enals by reaction of (2E)-4,4-dimethoxybut-2- enals and Grignard compounds. Thermal isomerization of (2E)-4-hydroxyalk-2-enals gave the corresponding 2-alkylfurans.
- Garibyan,Ovanesyan,Makaryan,Petrosyan,Chobanyan
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experimental part
p. 406 - 409
(2010/09/12)
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- Uebergangsmetallkatalysierte Dimerisierung von Allenylketonen
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Stichworte: Allene, Furane, Palladiumverbindungen
- Stephen, A.,Hashmi, K.
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p. 1749 - 1751
(2007/10/02)
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- HETEROCYCLIZATION OF β,γ-DICHLORO KETONES AS A METHOD FOR THE SYNTHESIS OF FURAN DERIVATIVES
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Dichloro ketones obtained from acyl chlorides and allyl or β-methylallyl chloride undergo spontaneous cyclization to give 2-alkyl- and 2,4-dialkylfurans when they are heated; the intermediates in the case of 2,3-dichloropropene split out a molecule of hydrogen chloride to give 3,4-dichloro-2-butenones.
- Mamedov, E. J.,Ismailov, A. G.,Kozhushkov, S. I.,Zefirov, N. S.
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p. 260 - 265
(2007/10/02)
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- CHEMISTRY OF SYSTEMS OF THE ALLYLIC TYPE II. ACYLATION OF 3-BROMO- AND 2-METHYL-3-CHLORO-1-PROPENES
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The acylation of 3-bromo- and 2-methyl-3-chloro-1-propenes under the conditions of the Kondakov-Krapivin reaction showed that the addition of acyl chlorides to these compounds takes place according to the Markovnikov rule with formation of the corresponding halogen-containing α-β-unsaturated ketones and alkyl(cycloalkyl)furans.
- Ibragimov, I. I.,Mamedov, E. I.,Ismailov, A. T.,Aliev, A. G.,Mekhtieva, Sh. Z.,et al.
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p. 1425 - 1430
(2007/10/02)
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- SYNTHESIS AND PROPERTIES OF 1-(2-BROMOETHYL)-, 1-(2-ALKOXYETHYL)- AND 1-(2-DIALKYLAMINOETHYL)-2-ALKYLPYRROLES
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The reaction of 3-chloropropenyl alkyl ketones or 2,3-dichloropropyl alkyl ketones with 2-substituted ethylamine derivatives leads to the formation of the hitherto unknown 1-(2-R-ethyl)-2-alkylpyrroles.
- Gadzhily, R. A.,Fedoseev, V. M.,Nadzhafova, R. A.,Dzhafarov, V. G.
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p. 874 - 876
(2007/10/02)
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- Synthesis and Characterisation of some 1,4,8,11,15,18,22,25-Octa-alkyl- and 1,4,8,11,15,18-Hexa-alkyl-22,25-bis(carboxypropyl)phthalocyanines
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A series of 3,6-dialkylphthalonitriles and 3,6-bis(4,4,4-trimethoxybutyl)phthalonitrile have been prepared via Diels-Alder reactions of 2,5-disubstituted furans or thiophene 1,1-dioxides with fumaronitrile.The phthalonitriles were converted into the title phthalocyanines as metal-free and copper(II) derivatives.The macrocycles were characterised using 1H NMR and optical spectroscopy, and fastatom bombardment spectrometry.Certain examples exhibit discotic liquid crystal behaviour.
- McKeown, Neil B.,Chambrier, Isabelle,Cook, Michael J.
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p. 1169 - 1177
(2007/10/02)
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