- Synthesis and mass spectra of rearrangement bio-signature metabolites of anaerobic alkane degradation via fumarate addition
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Metabolite profiling in anaerobic alkane biodegradation plays an important role in revealing activation mechanisms. Apart from alkylsuccinates, which are considered to be the usual biomarkers via fumarate addition, the downstream metabolites of C-skeleton rearrangement can also be regarded as biomarkers. However, it is difficult to detect intermediate metabolites in both environmental samples and enrichment cultures, resulting in lacking direct evidence to prove the occurrence of fumarate addition pathway. In this work, a synthetic method of rearrangement metabolites was established. Four compounds, namely, propylmalonic acid, 2-(2-methylbutyl)malonic acid, 2-(2-methylpentyl)malonic acid and 2-(2-methyloctyl)malonic acid, were synthesized and determined by four derivatization approaches. Besides, their mass spectra were obtained. Four characteristic ions were observed at m/z 133 + 14n, 160 + 28n, 173 + 28n and [M - (45 + 14n)]+ (n = 0 and 2 for ethyl and n-butyl esters, respectively). For methyl esterification, mass spectral features were m/z 132, 145 and [M - 31]+, while for silylation, fragments were m/z 73, 147, 217, 248, 261 and [M - 15]+. These data provide basis on identification of potential rearrangement metabolites in anaerobic alkane biodegradation via fumarate addition.
- Chen, Jing,Zhou, Lei,Liu, Yi-Fan,Hou, Zhao-Wei,Li, Wei,Mbadinga, Serge Maurice,Zhou, Jing,Yang, Tao,Liu, Jin-Feng,Yang, Shi-Zhong,Wu, Xiao-Lin,Gu, Ji-Dong,Mu, Bo-Zhong
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- Oxidative esterification of aliphatic aldehydes and alcohols with ethanol over gold nanoparticle catalysts in batch and continuous flow reactors
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Selective esterification of aliphatic aldehydes and alcohols with ethanol in the absence of a base is a more difficult reaction than that with methanol. Gold nanoparticles on ZnO were found to catalyze the oxidative esterification of octanal to ethyl octanoate with high selectivity. In addition, it was found that Au/ZnO was the most effective catalyst for yielding the desired ethyl ester without a base by direct esterification of 1-octanol with ethanol. As far as we know, this is the first report on oxidative esterification to give aliphatic ethyl esters from less reactive aliphatic alcohols and aldehydes without a base. The optimal size of gold NPs ranged from 2 to 6 nm and the presence of Au(0) was indispensable for this reaction. Au/ZnO exhibited the highest catalytic activity in both batch and flow reactors. The conversion was maintained for more than 20 h with 95% selectivity to the desired ethyl ester in the flow system.
- Taketoshi,Ishida,Murayama, Toru,Honma, Tetsuo,Haruta, Masatake
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- Palladium complexes with N-heterocyclic carbene ligands as catalysts for the alkoxycarbonylation of olefins
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Palladium catalysts, generated from Pd(OAc)2 and 2 equiv of N,N-dialkylbenzimidazolium iodide, are effective for the alkoxycarbonylation of olefins in high yields (>90%). Alkoxycarbonylation of 1-hexene in dimethylacetamide is achieved within 24 h at 110 C using 1 mol % catalyst, 1000 psi CO, and ethanol. Reactions can be prepared in air, without the need of an acid additive to produce ethyl 2-methylhexanoate and ethyl heptanoate in approximately a 2:1 ratio.
- Roberts, Gina M.,Pierce, Philip J.,Woo, L. Keith
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p. 2033 - 2036
(2013/05/21)
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- Highly enantioselective iridium-catalyzed hydrogenation of α,β-unsaturated esters
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α,β-Unsaturated esters have been employed as substrates in iridium-catalyzed asymmetric hydrogenation. Full conversions and good to excellent enantioselectivities (up to 99 % ee) were obtained for a broad range of substrates with both aromatic- and aliphatic substituents on the prochiral carbon. The hydrogenated products are highly useful as building blocks in the synthesis of a variety of natural products and pharmaceuticals. Asymmetric hydrogenation: A variety of α,β-unsaturated esters were hydrogenated with high enantioselectivities (see scheme). The hydrogenated products have been used in synthetic transformations as well as in formal total syntheses. Copyright
- Li, Jia-Qi,Quan, Xu,Andersson, Pher G.
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supporting information
p. 10609 - 10616
(2012/11/07)
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- The Esterification of Carboxylic Acid with Alcohol over Hydrous Zirconium Oxide
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The esterification of carboxylic acids with alcohols proceeded efficienly with hydrous zirconium oxide to give the corresponding esters in the vapor phase, in the liquid phase, and in an autoclave.The steric hindrance of carboxylic acids and alcohols affected the esterification by lowering the reactivity.With a rise in the reaction temperature, the conversion of the carboxylic acid increased.The dehydration of alcohols was prevented by using hydrous zirconium oxide in spite of the high reaction temperature.The reaction rate is first-order with respect to the concentration of the catalyst and an alcohol and is inversely proportional to thta of the carboxylic acid.Transesterification also proceeded efficiently.
- Takahashi, Kyoko,Shibagaki, Makoto,Matsushita, Hajime
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p. 2353 - 2361
(2007/10/02)
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- ACTIVATION OF MIXED CARBOXILIC α-BROMOTOLUOYL ANHYDRIDES BY SILVER TETRAFLUOROBORATE. SYNTHESIS OF ESTERS AND THIOL ESTERS
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Mixed carboxylic α-bromotoluoyl anhydrides were activated by silver tetrafluoroborate through intramolecular cyclization and reacted with alcohols or thiols giving the corresponding esters or thiol esters in good yields with the elimination of phtalide.
- Fukuoka, Satoshi,Takimoto, Seiji,Katsuki, Tsutomu,Yamaguchi, Masaru
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p. 4711 - 4712
(2007/10/02)
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- Studies on the Intramolecular Claisen Condensation. Stereospecific Ring-closure of β-Acetyloxy Esters
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On treatment with lithium bis(trimethylsilyl)amide, α-alkyl-β-acetyloxy esters (2) and (3) undergo stereospecific ring-closure to the 5,6-dihydro-4-hydroxy-2H-pyran-2-ones (2,4-dioxotetrahydropyrans) (4) and (5).
- Brandaenge, Svante,Leijonmarck, Hans
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p. 1097 - 1098
(2007/10/02)
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- A Simple and Efficient Conversion of Aldehyde Acetals into Esters
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The reaction of aldehydic acetals with hypochlorous acid in acetic acid-acetone afforded the corresponding esters in excellent yields.From cyclic acetals, only the corresponding hydroxyalkyl esters were obtained.Keywords - acetal; hypochlorite; hypochlorous acid; conversion; ester; hydroxyalkyl ester; regioselectivity
- Sugai, Saburo,Kodama, Takashi,Akaboshi, Sanya,Ikegami, Shiro
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