1002-84-2Relevant articles and documents
Iron-catalyzed AlkylAlkyl negishi coupling of organoaluminum reagents
Agata, Ryosuke,Kawamura, Shintaro,Isozaki, Katsuhiro,Nakamura, Masaharu
, p. 238 - 241 (2019)
The first iron-catalyzed cross-coupling reaction of alkyl halides with alkylaluminum reagents (alkylalkyl Negishi coupling) is developed using an iron/bisphosphine catalyst system. The reaction shows high functional group tolerance: various primary alkyl halides possessing a non-protected indole, carboxyl, or hydroxy group are coupled with primary alkylaluminum reagents in good yields. Potassium fluoride plays a key role to promote the reaction by generating an aluminate species, which facilitates the transmetalation between the organoaluminum and the iron catalyst.
Efficient oxidative cleavage of olefins to carboxylic acids with hydrogen peroxide catalyzed by methyltrioctylammonium tetrakis(oxodiperoxotungsto)phosphate(3-) under two-phase conditions. Synthetic aspects and investigation of the reaction course
Antonelli, Ermanno,D'Aloisio, Rino,Gambaro, Mario,Fiorani, Tiziana,Venturello, Carlo
, p. 7190 - 7206 (1998)
The oxidative cleavage of alkenes to carboxylic acids with 40% w/v aqueous hydrogen peroxide catalyzed by methyltrioctylammonium tetrakis(oxodiperoxotungsto)phosphate(3-) (1a) is reported to occur in high yields and selectivities under two-phase conditions in the absence of organic solvents. On the basis of a study of the reaction, two main reaction pathways leading to acids have been recognized, the first one involving the perhydrolysis and the second one the hydrolysis of the epoxide initially formed. The "perhydrolytic" reaction pathway appears to play a primary role in the oxidation of medium- and long-chain alkenes to acids, while it intervenes to a rather limited extent in the oxidation of arylalkenes and C5-C7 cycloalkenes. The occurrence of this pathway has been proved by the isolation of the intermediate β-hydroperoxy alcohols and their transformation into acids with H2O2 and la. The course of this transformation, involving an initial oxidation (to α-oxo hydroperoxide) or decomposition (to carbonyl compounds) of the β-hydroperoxy alcohol intermediate, is described. The primary oxidation products, α-hydroperoxy ketones, have been isolated in the case of internal β-hydroperoxy alcohols, whereas their presence has been evidenced with terminal β-hydroperoxy alcohols bearing a secondary hydroxy group. Hydrogen peroxide concentration appears to exert a remarkable influence on medium acidity, and its effects on the reaction efficiency are shown.
Determination of Key Hydrocarbon Autoxidation Products by Fluorescence
Shah, Ron,Pratt, Derek A.
, p. 6649 - 6656 (2016)
Hydroperoxides and carboxylic acids are key primary products that arise in the autoxidation of hydrocarbons. We have developed a simple approach to rapidly and simultaneously determine both types of products using hydroperoxide- and acid-sensitive moieties conjugated to nonpolar coumarin- and BODIPY-based fluorophores. The coumarin- and BODIPY-conjugated amine probes described here undergo 38- and 8-fold enhancement, respectively, upon protonation in a solvent system compatible with heavy hydrocarbons. The latter can be used directly with our previously described hydroperoxide-sensitive coumarin-conjugated phosphine probe to enable rapid quantification of both carboxylic acids and hydroperoxides in hydrocarbon samples. The utility of the approach is illustrated by the ready determination of the differing relative rates of hydroperoxide and acid formation with changes in hydrocarbon structure (e.g., n-hexadecane vs 1-hexadecene vs a lubricant base stock). The method offers significant versatility and automation compared with common but laborious titration approaches, and greatly improves screening efficiency and accuracy for the identification of novel radical-trapping antioxidants for high temperature applications. This application was demonstrated by the automated analysis of hydroperoxides and carboxylic acids (by microplate reader) in samples from 24 inhibited autoxidations of a lubricating oil, which were carried out on a parallel synthesizer at 160 °C in triplicate in a single day.
Enantioselective α-hydroperoxylation of long-chain fatty acids with crude enzyme of marine green alga Ulva pertusa
Akakabe,Matsui,Kajiwara
, p. 1137 - 1140 (1999)
When palmitic acid was incubated with crude enzyme of marine green alga Ulva pertusa, (R)-2-hydroperoxyhexadecanoic acid was formed in high enantiomeric purity (>99%ee).
Release of nicotinamide from fatty acid-nicotinamide equimolar complexes
Yokoyama,Ueda,Fujie
, p. 3075 - 3076 (1991)
The release behavior of nicotinamide (NAA) from fatty acid (FA)-NAA equimolar complexes was examined in a JP XI dissolution test apparatus in JP XI disintegration test medium No. 1 (pH 1.2) at 37°C where the carbon number of FA is 14-18. The time required for 50% or 80% of NAA to release (T50 or T80) was measured, and the effect of the constituent FA on T50 or T80 was investigated. The values of T50 or T80 for FA-NAA formed with odd-numbered FA were larger than those for FA-NAA formed with even-numbered FA whose alkyl chain length is one more carbon number longer, though the values of T50 of T80 increased rather regularly with an increase of the alkyl chain length for only even-numbered or odd-numbered FA. The values of T50 and T80 for FA-NAA formed with heptadecanoic acid (C17-NAA) were about 36 and 102 min, respectively, suggesting that C17-NAA may be applicable to the preparaton of a sustained-release drug formulation.
A Comprehensive Study on Metal Triflate-Promoted Hydrogenolysis of Lactones to Carboxylic Acids: From Synthetic and Mechanistic Perspectives
Zhu, Rui,Jiang, Ju-Long,Li, Xing-Long,Deng, Jin,Fu, Yao
, p. 7520 - 7528 (2017)
Direct hydrogenolysis of lactone to carboxylic acid (i.e., hydrogenolysis of the Calkoxy-O bond with the carbonyl group untouched) is generally difficult, as the current strategies employing Br?nsted acids as the catalyst usually require harsh conditions such as a high temperature and a high H2 pressure. Herein, we report a developed solvent-free catalytic transformation, in which W(OTf)6 is believed to promote the hydrogenolysis process. This strategy could efficiently hydrogenate lactones to carboxylic acids under extra mild conditions (e.g., a reaction temperature of 2) and showed a broad substrate scope. In addition, the catalytic protocol can be further applied to the hydrogenolysis of polyhydroxyalkanoate, as a renewable polymer, to the corresponding straight-chain carboxylic acids. An extensive mechanistic study was subsequently performed, and the density functional theory calculations revealed a reaction pattern, including the complete cleavage of the C=O bond with the assistance of the W(OTf)6 catalyst. Moreover, the key intermediate created in the mechanism, as an oxonium with an OTf moiety, was successfully detected by electrospray ionization mass spectra. Through a comparison with the Br?nsted acid-catalyzed system, the study confirmed that the existence of the OTf moiety can significantly lower the barriers associated with the rearrangement and elimination processes. Meanwhile, emphasis was placed on the critical role that the anion plays, as well as the fact that the anion effect is directly related to the chemoselectivity.
New 19α-hydroxyursane-type triterpenes from the leaves of Meyna spinosa (= Vangueria spinosa), Rubiaceae
Rudrapaul, Prasenjit,Das, Niranjan,De, Utpal Chandra,Dinda, Biswanath
, p. 7 - 10 (2014)
Two new 19α-hydroxyursane-type triterpenes, 2α,3α, 19α,24,28-pentahydroxyurs-12-ene (1) and meyanthic acid, 3β-acetoxy-2β,19α,23-trihydroxyurs-12-en-28-oic acid (2) along with one new aliphatic ester, myricyl pentadecanoate (3) and five known compounds, 1
Release kinetics of nicotinamide from fatty acid-nicotinamide equimolar complexes. I. Release characteristics of fatty acid complexes
Yokoyama,Ueda,Fujie
, p. 2696 - 2698 (1991)
The rates of release of nicotinamide (NAA) from fatty acid (FA)-NAA complexes, FA-NAA, were determined in a JP XI dissolution test apparatus in 500 ml of JP XI disintegration test medium No. 1 at 37°C. The release rate constant (k) and the activation Gibbs energy (ΔG+) for the release of NAA from FA-NAA were estimated. The results obtained for FA-NAA were compared with previous results obtained for the thiamine disulfide (TDS) complex, (FA)6-(TDS). The plots of log k against the carbon number of the constituent FA (n) presented a zig-zag line which indicates a downward convex at an odd-numbered position. The plots of ΔG+ against n showed a zig-zag line with an upward convex at an odd-numbered position, though the positive value of ΔG± increased rather regularly with an increase of n for either even-numbered or odd-numbered FA. The phenomena that the plots of log k vs. n and ΔG+ vs. n show zig-zag lines due to the difference between even- and odd-numbered FA were the same as observed previously for the release of TDS from (FA)6 (TDS).
Synthesis of Carboxylic Acids by Palladium-Catalyzed Hydroxycarbonylation
Sang, Rui,Kucmierczyk, Peter,Dühren, Ricarda,Razzaq, Rauf,Dong, Kaiwu,Liu, Jie,Franke, Robert,Jackstell, Ralf,Beller, Matthias
supporting information, p. 14365 - 14373 (2019/09/06)
The synthesis of carboxylic acids is of fundamental importance in the chemical industry and the corresponding products find numerous applications for polymers, cosmetics, pharmaceuticals, agrochemicals, and other manufactured chemicals. Although hydroxycarbonylations of olefins have been known for more than 60 years, currently known catalyst systems for this transformation do not fulfill industrial requirements, for example, stability. Presented herein for the first time is an aqueous-phase protocol that allows conversion of various olefins, including sterically hindered and demanding tetra-, tri-, and 1,1-disubstituted systems, as well as terminal alkenes, into the corresponding carboxylic acids in excellent yields. The outstanding stability of the catalyst system (26 recycling runs in 32 days without measurable loss of activity), is showcased in the preparation of an industrially relevant fatty acid. Key-to-success is the use of a built-in-base ligand under acidic aqueous conditions. This catalytic system is expected to provide a basis for new cost-competitive processes for the industrial production of carboxylic acids.
Preparation method of carboxylic acid compound
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Paragraph 0113; 0131-0133, (2017/08/29)
The invention provides a preparation method of a carboxylic acid compound. The preparation method comprises the following step of taking a lactone component to react with hydrogen in the presence of a compound catalyst to obtain the carboxylic acid compound. The compound catalyst comprises a hydrogenation catalyst and Lewis acid. In the presence of the compound catalyst comprising the hydrogenation catalyst and the Lewis acid, the lactone component is subjected to hydrogenation ring-opening reaction to obtain the carboxylic acid compound. The preparation method has the advantages of moderate reaction conditions and high yield; compared with a traditional method, less byproducts are generated, green and chemical requirements are met and the industrial value is better.
