- One-pot conversion of alkyl aldehydes into substituted propanoic acids via Knoevenagel condensation with Meldrum's acid
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Reaction of a range of alkyl aldehydes and Meldrum's acid in triethylammonium formate (TEAF) at 100 °C generates substituted propanoic acids in a single step.
- Mudhar, Harminder,Witty, Andrew
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Read Online
- Synthetic method of acid compound
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The invention belongs to the field of organic synthesis, and particularly relates to a synthetic method of an acid compound. An acid anhydride compound and an alkyl bromide or a functionalized alkyl bromide are subjected to a cross-electrophilic coupling reaction to synthesize an acid compound, so that the application of the alkyl bromide in the cross-electrophilic coupling reaction is expanded, and a novel non-traditional method for chemically and selectively constructing a carbon-carbon bond through a decarburization process is provided. The synthesis method is simple, economic, green and environment-friendly, and has wider applicability or is suitable for large-scale production.
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Paragraph 0028-0033; 0041
(2020/08/25)
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- Zinc Oxide-Catalyzed Dehydrogenation of Primary Alcohols into Carboxylic Acids
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Zinc oxide has been developed as a catalyst for the dehydrogenation of primary alcohols into carboxylic acids and hydrogen gas. The reaction is performed in mesitylene solution in the presence of potassium hydroxide, followed by workup with hydrochloric acid. The transformation can be applied to both benzylic and aliphatic primary alcohols and the catalytically active species was shown to be a homogeneous compound by a hot filtration test. Dialkylzinc and strongly basic zinc salts also catalyze the dehydrogenation with similar results. The mechanism is believed to involve the formation of a zinc alkoxide which degrades into the aldehyde and a zinc hydride. The latter reacts with the alcohol to form hydrogen gas and regenerate the zinc alkoxide. The degradation of a zinc alkoxide into the aldehyde upon heating was confirmed experimentally. The aldehyde can then undergo a Cannizzaro reaction or a Tishchenko reaction, which in the presence of hydroxide leads to the carboxylic acid.
- Monda, Fabrizio,Madsen, Robert
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supporting information
p. 17832 - 17837
(2018/11/23)
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- Structure activity studies with xenobiotic substrates using carboxylesterases isolated from Arabidopsis thaliana
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Carboxylesterases (CXEs) catalyse the hydrolysis of xenobiotics and natural products radically altering their biological activities. Whereas the substrate selectivity of animal CXEs, such as porcine liver esterase (PLE) have been well studied, the respective enzymes in plants have yet to be defined and their activities determined. Using Arabidopsis thaliana (At) as a source, five representative members of the α/β hydrolase AtCXE family of proteins have been cloned, expressed and the purified recombinant proteins assayed for esterase activity with xenobiotic substrates. Two members, AtCXE5 and AtCXE18 were found to be active carboxylesterases, though AtCXE5 proved to be highly unstable as a soluble protein. AtCXE18 and the previously characterised S-formylglutathione hydrolase from Arabidopsis (AtSFGH) were assayed against a series of esters based on methylumbelliferone in which the acyl moiety was varied with respect to size and conformation. The same series was used to assay crude esterase preparation from Arabidopsis plants and the results compared with those obtained with the commonly used PLE. With straight chain esters, AtCXE18 behaved like PLE, but the Arabidopsis hydrolases proved less tolerant of branched chain acyl components than the mammalian enzyme. While none of the enzyme preparations accurately reflected all the activities determined with crude Arabidopsis protein extracts, the plant enzymes proved more useful than PLE in predicting the hydrolysis of the more sterically constrained esters.
- Cummins, Ian,Landrum, Marie,Steel, Patrick G.,Edwards, Robert
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p. 811 - 818
(2008/03/13)
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- Shape and aggregating tendency. The aggregating behavior of eight esters of eight-carbon carboxylic acids
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The aggregating tendencies of eight p-nitrophenyl esters of eight-carbon carboxylic acids (1-8) and two O-octyl phosphonates (10, 11) have been evaluated by measuring their critical aggregate concentrations (CAgG's). Results show that (1) branching reduce
- Jiang, Xi-Kui,Ji, Guo-Zhen,Tu, Bo,Zhang, Xin-Yu,Shi, Ji-Liang,Chen, Xin
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p. 12679 - 12682
(2007/10/03)
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- Oxidative Cleavage of Methyl Ethers Using the HOF*CH3CN Complex
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HOF*CH3CN complex, made easily by bubbling fluorine diluted with nitrogen through aqueous acetonitrile, proved to be a suitable oxidizer for various methyl ethers.Secondary ethers are oxidized to ketones and even to lactones via Baeyer-Villiger type of oxidation.The reaction is ionic, and the reagent's electrophilic oxygen attacks the relatively electron rich C-H bond α to the ether moiety.It was found that the more sterically hindered is the C-H bond in question, the slower the reaction.In cases where this bond is an electron poor one as in benzoin methyl ether (9), no reaction takes place.When labeled H(18)OF*CH3CN is used on a (16)O methyl ether, the resulting ketone possesses only the heavier oxygen isotope.Primary methyl ethers are somewhat slower to react, but they too were oxidized in very good yields to acids via the corresponding aldehydes.
- Rozen, Shlomo,Dayan, Sharon,Bareket, Yifat
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p. 8267 - 8269
(2007/10/03)
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- Process for the preparation of cycloalkylalkane carboxylic acid
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A process is disclosed for effectively producing a cycloalkylalkane carboxylic acid by reacting a cyclic ketone or a cyclic alcohol with a molten alkali metal hydroxide using a two step temperature treatment during the reaction wherein the first step temperature ranges from 200° to 270°C and the second step temperature ranges from 290° to 350°C. The alkali metal soap is then converted to the free acid. The process is especially directed to the manufacture of cyclopentylpropionic acid.
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