1191-25-9Relevant articles and documents
Oxidation of KA oil to caprolactone with molecular oxygen using N-hydroxyphthalimide-mediated Ce(NH4)2(NO3)6 catalyst
Du, Renfeng,Yuan, Haoran,Yao, Jia,Li, Haoran
, p. 24 - 29 (2019)
In traditional Baeyer-Villiger oxidation, peracids or hydrogen peroxide are usually adopted as the oxidants. When molecular oxygen is used as oxidant, the sacrificial agents are always indispensable, such as aldehydes that are transformed into cheap acids after reaction. In this work, KA oil (the industrial raw material, a mixture of cyclohexanol and cyclohexanone) has been oxidized to caprolactone by molecular oxygen using N-hydroxyphthalimide (NHPI) and cerium ammonium nitrate (CAN) as catalyst, in which the sacrificial agent is cyclohexanol, and it is converted into cyclohexanone, then into caprolactone rather than into byproducts. The selectivity of caprolactone was 98% with cyclohexanol conversion of 34% and it was still kept at 90% when the conversion reached to 46%. The mechanism investigation showed a bifunctional role of CAN, which performed both as a radical initiator for cyclohexanol oxidation and a Lewis acid for Baeyer-Villiger reaction. In the Baeyer-Villiger oxidation, a weak interaction between cerium and cyclohexanone was suggested by Fourier Transform Infrared Spectroscopy (FTIR), meanwhile, the active species generated from cerium and hydrogen peroxide was separated and characterized by FTIR. The detailed research also revealed an unusual effect between cerium and the Br?nsted acid generated as a byproduct, which was critical for caprolactone synthesis.
Ruthenium-catalyzed highly chemoselective hydrogenation of aldehydes
Bonomo, Lucia,Kermorvan, Laurent,Dupau, Philippe
, p. 907 - 910 (2015)
The use of a [(ethylenediamine)(dppe)Ru(OCOtBu)2] [dppe=1,2-bis(diphenylphosphino)ethane] complex under base-free conditions allowed highly efficient and selective hydrogenation of aldehydes in the presence of ketones in addition to olefins. Even in the case of highly sensitive 1,6-ketoaldehydes, the desired ketoalcohols were obtained in high yields with 94-99 % overall selectivity at complete aldehyde conversion with a TON up to 30 000. The lack of requirement for strong basic co-catalysts and polar protic solvents also allowed efficient and highly chemoselective reduction of aldehydes bearing other functional groups, such as epoxides, carboxylic acids, esters, amides, and nitriles emphasizing the potential synthetic utility of the catalyst. It's all about the aldehyde: The use of [(ethylenediamine)(dppe)Ru(OCOtBu)2] [dppe=1,2-bis(diphenylphosphino)ethane] under base-free conditions allows highly efficient and selective hydrogenation of aldehydes in the presence of ketones. Highly selective hydrogenation of additional aldehydes in the presence of other functional groups, such as epoxides, carboxylic acids, esters, amides, and nitriles emphasizes the potential synthetic utility of the catalyst.
Baeyer-Villiger oxidations with hydrogen peroxide in fluorinated alcohols: Lactone formation by a nonclassical mechanism
Berkessel, Albrecht,Andreae, Marc R. M.,Schmickler, Hans,Lex, Johann
, p. 4481 - 4484 (2002)
What a difference the solvent makes! Unlike in conventional solvents, non-strained ketones such as cyclohexanone react smoothly with hydrogen peroxide in 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) to give lactones. The reaction proceeds via an isolatable spiro-bisperoxide, which undergoes a highly exothermic acid-catalyzed rearrangement to two equivalents of lactone (see Equation and IR thermogram).
Solid-phase synthesis of a library of linear oligoester ion-channels
Fyles, Thomas Murray,Luong, Horace
, p. 725 - 732 (2009)
A solid-phase synthesis protocol was used to prepare fifteen new linear tetra-, and penta-esters structurally related to an active lead compound. The structures were assembled from three types of hydroxyl protected building blocks: monoalkyl esters of hydroxyglutaric acid, ω-hydroxyacids, and α-hydroxymethylalkanoic acids. The standard methodology gave acceptable quantities of material free of small molecule impurities. Mass spectrometric analysis revealed the presence of deletions due to incomplete coupling, as well as additions and macrolactones due to partial acidic rearrangement on release from the solid-support. The amount of these impurities could be estimated from the 1H NMR spectra, and their implications for subsequent activity analysis are discussed.
Hydrolytic degradation of poly(ethylene oxide)-block-polycaprolactone worm micelles
Geng, Yan,Discher, Dennis E.
, p. 12780 - 12781 (2005)
Spherical micelles and nanoparticles made with degradable polymers have been of great interest for therapeutic application, but degradation-induced changes in a spherical morphology can be subtle and mechanism/kinetics appears poorly understood. Here, we report the first preparation of giant and flexible worm micelles self-assembled from degradable copolymer poly(ethylene oxide)-block-polycaprolactone. Such worm micelles spontaneously shorten to generate spherical micelles, triggered by polycaprolactone hydrolysis, with distinct mechanism and kinetics from that which occurs in bulk material. Copyright
Lipase-catalyzed ring-opening polymerizations of 4-substituted ε-caprolactones: Mechanistic considerations
Peeters, Joris W.,Van Leeuwen, Oscar,Palmans, Anja R. A.,Meijer
, p. 5587 - 5592 (2005)
Lipase-catalyzed ring-opening polymerizations of 4-substituted ε-caprolactones employing Novozym 435 as the biocatalyst demonstrate dramatic differences in polymerization rates and selectivity depending on the size of the substituent. Quantification of the reaction rates shows that the polymerization rate decreases by a factor of 2 upon the introduction of a Me substituent at the 4-position. Moreover, 4-EtCL polymerizes 5 times slower than 4-MeCl and 4-PrCL is even 70 times slower. The decrease in polymerization rate is accompanied by a strong decrease in enantioselectivity: while the E-ratio of 4-MeCL polymerization is 16.9, the E-ratios of 4-EtCL and 4-PrCL are 7.1 and 2.0, respectively. Interestingly, Novozym 435 displays S-selectivity for 4-MeCL and 4-EtCL in the polymerization reaction, but the enantioselectivity is changed to the (R)-enantiomer in the case of the 4-PrCL. The nature of these differences was investigated by hydrolyzing all monomers in water/diisopropyl ether mixtures employing Novozym 435 as the catalyst. In the hydrolysis reactions, the rates are only moderately affected upon increasing the substituent size, and the enantioselectivity is S in all cases, also for 4-PrCL. Again, a steady decrease of the U-ratio was observed upon increasing the substituent size, but this was less pronounced than in the polymerization reactions: the E-ratios were 17.6, 12.4, and 4.6, going from 4-MeCL to 4-PrCL. For 4-substituted ε-caprolactones, the results obtained are a clear indication that the chirality of the propagating alcohol chain end is important in the catalytic cycle and that-in contrast to unsubstituted lactones-the rate-determining step is not necessarily the formation of the acyl-enzyme intermediate but more likely the deacylation of the acyl-enzyme intermediate by the propagating alcohol chain end.
A highly stable and active CaO/Al2O3 base catalyst in the form of calcium aluminate phase for oxidation of cyclohexanone to ε-caprolactone
Zhu, Lihua,Cao, Maohong,Zhou, Hua,Zhang, Nuowei,Zheng, Jinbao,Li, Yunhua,Chen, Bing H.
, p. 1188 - 1196 (2014)
A series of CaO/Al2O3 base catalysts with different crystal phases is prepared via thermal treatment. The as-prepared base catalysts are tested through Baeyer-Villiger oxidation of cyclohexanone to ε-caprolactone in liquid-phase using a mixture of aqueous hydrogen peroxide and benzonitrile as oxidant. The corresponding results show that the CaO/Al2O3 catalysts with high thermal treatment temperature (e.g. 900 °C) exhibit excellent activity as well as stability. Upon these, the catalysts are characterized by TG-DTG, XRD, N 2-physisorption, SEM and CO2-TPD techniques. The characterization results clearly suggest that such a stable and efficient catalytic performance is beneficial from the formation of calcium aluminate phase, thus overcoming one of base catalyst application barriers, that Ca or CaO species loss (leach) from CaO-based catalysts during reactions. Correspondingly, it can be inferred that the treatment of the catalysts at different temperatures results in the diverse distribution of basic strength. Furthermore, it is also demonstrated that the suitable base strength (medium strength is good for the reaction selected in the work) plays a critically role in the improvement of catalytic performance. Finally, the effects of operation conditions on catalytic activity and product selectivity are also determined and discussed.
Oxidation of cyclohexane with hydrogen peroxide over β-zeolites with various Si/Al ratios
Ohno, Ryohei,Taniya, Keita,Tsuruya, Shigeru,Ichihashi, Yuichi,Nishiyama, Satoru
, p. 60 - 65 (2013)
Selective oxidation of cyclohexanone to ε-caprolactone by H 2O2 was investigated on β-zeolites with various Si/Al ratio. The yield of ε-caprolactone was increased with decreasing Si/Al ratio. The β-zeolites in which Si/Al ratio was l
Selective oxidation of 1,6-hexanediol to 6-hydroxycaproic acid over reusable hydrotalcite-supported au-pd bimetallic catalysts
Tuteja, Jaya,Nishimura, Shun,Choudhary, Hemant,Ebitani, Kohki
, p. 1862 - 1866 (2015)
Selective oxidation of 1,6-hexanediol into 6-hydroxycaproic acid was achieved over hydrotalcite-supported Au-Pd bimetallic nanoparticles as heterogeneous catalyst using aqueous H2O2. N,N-dimethyldodecylamine N-oxide (DDAO) was used as an efficient capping agent. Spectroscopic analyses by UV/Vis, TEM, XPS, and X-ray absorption spectroscopy suggested that interactions between gold and palladium atoms are responsible for the high activity of the reusable Au40Pd60-DDAO/HT catalyst. Talcite assumptions: Au-Pd nanoparticles stabilized by N,N-dimethyldodecylamine N-oxide (DDAO) and on a hydrotalcite support are prepared. The supported nanoparticles are employed for the selective oxidation of 1,6-hexanediol to 6-hydroxycaproic acid in alkaline medium with 30% aq. H2O2 as oxidant. Analysis of the catalysts by a combination of spectroscopic techniques reveals electronic interactions between gold an palladium that are responsible for the catalytic performance.
Oxidative ring contraction of cycloalkanones: A facile metrod for synthesis of medium ring cycloalkanecarboxylic acids
Giurg, Miroslaw,Mlochowski, Jacek
, p. 2281 - 2291 (1999)
Cycloalkanones (1) oxidized with 30% hydrogen peroxide in the presence of poly(bisanthracenyl) diselenide (5b) as catalyst, produce cycloalkanecarboxylic acids (2) having one carbon atom less in the ring that the substrate. Although preparative yield of acids 2 does not exceed 60% the reaction can be applied as a simple way for synthesis of cycloalkanecarboxylic acids with five to seven-membered ring.
Change in reactivity of differently capped AuPd bimetallic nanoparticle catalysts for selective oxidation of aliphatic diols to hydroxycarboxylic acids in basic aqueous solution
Tuteja, Jaya,Nishimura, Shun,Ebitani, Kohki
, p. 231 - 239 (2016)
N,N-Dimethyldodecylamine N-oxide (DDAO), PVP and PVA capped supported AuPd bimetallic nanoparticles (NPs) were prepared, and their catalytic activities were evaluated for the oxidation of 1,6-hexanediol (HDO) to 6-hydroxycaproic acid (HCA) using H2O2 in basic aqueous solution. Among three catalysts, DDAO capped AuPd bimetallic NPs catalysts exhibited superior selectivity for HCA formation than PVP and PVA capped catalysts. To explain the difference in the catalytic behavior, the catalysts were characterized thoroughly. XRD, TEM and STEM-HAADF-EDS studies were employed to identify the structure and morphology of capped AuPd-NPs, respectively. The chemical and electronic states were elucidated using XPS and XAS methods. The characterization data revealed that the capping agent significantly influences the electron density on metals and extent of alloying between Au and Pd metals. It was revealed that DDAO-capped catalyst induces appropriate negatively charged Au species with a few numbers of Au-Pd interfaces for the highly selective formation of HCA via HDO oxidation in basic aqueous media. Furthermore, other aliphatic diols, 1,7-heptanediol, 1,8-octanediol and 1,2-hexanediol, were also selectively oxidized on AuPd-DDAO catalysts toward the corresponding ω-hydroxycarboxylic acids in high yields.
Supported sulfonic acid as green and efficient catalyst for Baeyer-Villiger oxidation with 30% aqueous hydrogen peroxide
Piscopo, Calogero G.,Loebbecke, Stefan,Maggi, Raimondo,Sartori, Giovanni
, p. 1625 - 1629 (2010)
Silica-supported propylsulfonic acid is a very good heterogeneous catalyst for the Baeyer-Villiger oxidation of cyclic ketones to lactones with stoichiometric 30% aqueous hydrogen peroxide in 1,1,1,3,3,3-hexafluoro-2- propanol as solvent.
Influence of Dioxygen on the Promotional Effect of Bi during Pt-Catalyzed Oxidation of 1,6-Hexanediol
Xie, Jiahan,Huang, Benjamin,Yin, Kehua,Pham, Hien N.,Unocic, Raymond R.,Datye, Abhaya K.,Davis, Robert J.
, p. 4206 - 4217 (2016)
A series of carbon-supported, Bi-promoted Pt catalysts with various Bi/Pt atomic ratios was prepared by selectively depositing Bi on Pt nanoparticles. The catalysts were evaluated for 1,6-hexanediol oxidation activity in aqueous solvent under different dioxygen pressures. The rate of diol oxidation on the basis of Pt loading over a Bi-promoted catalyst was 3 times faster than that of an unpromoted Pt catalyst under 0.02 MPa of O2, whereas the unpromoted catalyst was more active than the promoted catalyst under 1 MPa of O2. After liquid-phase catalyst pretreatment and 1,6-hexanediol oxidation, migration of Bi on the carbon support was observed. The reaction order in O2 was 0 over Bi-promoted Pt/C in comparison to 0.75 over unpromoted Pt/C in the range of 0.02-0.2 MPa of O2. Under low O2 pressure, rate measurements in D2O instead of H2O solvent revealed a moderate kinetic isotope effect (rateH2O/rateD2O) on 1,6-hexanediol oxidation over Pt/C (KIE = 1.4), whereas a negligible effect was observed on Bi-Pt/C (KIE = 0.9), indicating that the promotional effect of Bi could be related to the formation of surface hydroxyl groups from the reaction of dioxygen and water. No significant change in product distribution or catalyst stability was observed with Bi promotion, regardless of the dioxygen pressure.
Introducing an in situ capping strategy in systems biocatalysis to access 6-aminohexanoic acid
Sattler, Johann H.,Fuchs, Michael,Mutti, Francesco G.,Grischek, Barbara,Engel, Philip,Pfeffer, Jan,Woodley, John M.,Kroutil, Wolfgang
, p. 14153 - 14157 (2014)
The combination of two cofactor self-sufficient biocatalytic cascade modules allowed the successful transformation of cyclohexanol into the nylon-6 monomer 6-aminohexanoic acid at the expense of only oxygen and ammonia. A hitherto unprecedented carboxylic acid capping strategy was introduced to minimize the formation of the deadend intermediate 6-hydroxyhexanoic acid. For this purpose, the precursor ε-caprolactone was converted in aqueous medium in the presence of methanol into the corresponding methyl ester instead of the acid. Hence, it was shown for the first time that esterases-specifically horse liver esterase-can perform the selective ring-opening of ε-caprolactone with a clear preference for methanol over water as the nucleophile.
Comparative Baeyer-Villiger oxidation of cyclohexanone on Fe-pillared clays and iron tetrasulfophthalocyanine covalently supported on silica
Belaroui, Lala Setti,Sorokin, Alexander B.,Figueras, Fran?ois,Bengueddach, Abdelkader,Millet, Jean-Marc M.
, p. 466 - 472 (2010)
The Baeyer-Villiger oxidation of cyclohexanone to caprolactone has been investigated at room temperature over AlFe-pillared clays, using oxygen as oxidant in the presence of benzaldehyde. A nearly complete conversion is observed with a selectivity into ca
A Fed-Batch Synthetic Strategy for a Three-Step Enzymatic Synthesis of Poly-?-caprolactone
Scherkus, Christian,Schmidt, Sandy,Bornscheuer, Uwe T.,Gr?ger, Harald,Kara, Selin,Liese, Andreas
, p. 3446 - 3452 (2016)
A three-step enzymatic reaction sequence for the synthesis of poly-?-caprolactone (PCL) was designed running in a fed-batch operation. The first part of the cascade consisted of two oxidation steps starting with alcohol dehydrogenase catalyzed oxidation from cyclohexanol to cyclohexanone and further oxidation to ?-caprolactone (ECL) by means of a Baeyer–Villiger monooxygenase. As a third step, lipase-catalyzed hydrolysis of the lactone to 6-hydroxyhexanoic acid (6-HHA) was designed. With this biocatalytic multistep process reported herein, severe substrate surplus and product inhibition could be circumvented by the fed-batch operation by adding the cyclohexanol substrate and by in situ product removal of ECL by hydrolysis, respectively. Up to 283 mm product concentration of 6-HHA was reached in the fed-batch operated process without loss in productivity within 20 h. After extraction and subsequent polymerization catalyzed by Candida antarctica lipase B, analysis of the unfractionated polymer revealed a bimodal distribution of the polymer population, which reached a mass average molar mass (Mw) value of approximately 63 000 g mol?1 and a dispersity (Mw/Mn) of 1.1 for the higher molecular weight population, which thus revealed an alternative route to the conventional synthesis of PCL.
Carving the Active Site of CYP153A7 Monooxygenase for Improving Terminal Hydroxylation of Medium-Chain Fatty Acids
Chen, Qi,Chong, Gang-Gang,Dong, Ya-Li,Li, Ai-Tao,Li, Chun-Xiu,Pan, Jiang,Xu, Jian-He
, (2022/03/31)
The P450-mediated terminal hydroxylation of non-activated C?H bonds is a chemically challenging reaction. CYP153A7 monooxygenase, discovered in Sphingomonas sp. HXN200, belongs to the CYP153A subfamily and shows a pronounced terminal selectivity. Herein, we report the significantly improved terminal hydroxylation activity of CYP153A7 by redesign of the substrate binding pocket based on molecular docking of CYP153A7?C8:0 and sequence alignments. Some of the resultant single mutants were advantageous over the wild-type enzyme with higher reaction rates, achieving a complete conversion of n-octanoic acid (C8:0, 1 mM) in a shorter time period. Especially, a single-mutation variant, D258E, showed 3.8-fold higher catalytic efficiency than the wild type toward the terminal hydroxylation of medium-chain fatty acid C8:0 to the high value-added product 8-hydroxyoctanoic acid.
A gulose moiety contributes to the belomycin (BLM) disaccharide selective targeting to lung cancer cells
Cao, Yongjun,Chen, Wenming,Huang, Weiping,Li, Houkai,Liao, Guohao,Qi, Dongxia,Wang, Meizhu,Wang, Xiaoyang,Ye, Wenchong,Zhou, Cui,Zhou, Wen
, (2021/10/07)
Eight mono- or disaccharide analogues derived from BLM disaccharide, along with the corresponding carbohydate-dye conjugates have been designed and synthesized in this study, aiming at exploring the effect of a gulose residue on the cellular binding/uptake of BLM disaccharide and it possible uptake mechanism. Our evidence is presented indicating that, for the cellular binding/uptake of BLM disaccharide, a gulose residue is an essential subunit but unrelated to its chemical nature. Interestingly, D-gulose-dye conjugate is able to selectively target A549 cancer cells, but L-gulose-dye conjugate fails. Further uptake mechanism studies demonstrate D-gulose-dye derivatives similar to BLM disaccharide-dye ones behave in a temperature- and ATP-dependent manner, and are partly directed by the GLUT1 receptor. Moreover, D-gulose modifying gemcitabine 53a exhibits more potent antitumor activity compared to derivatives 53b-c in which gemcitabine is decorated with other monosaccharides. Taken together, the monosacharide D-gulose conjugate offers a new strategy for solving cytotoxic drugs via the increased tumor targeting in the therapy of lung cancer.
