- Systematic Engineering of Single Substitution in Zirconium Metal-Organic Frameworks toward High-Performance Catalysis
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Zirconium-based metal-organic frameworks (Zr-MOFs) exhibit great structural tunability and outstanding chemical stability, rendering them promising candidates for a wide range of practical applications. In this work, we synthesized a series of isostructural PCN-224 analogues functionalized by ethyl, bromo, chloro, and fluoro groups on the porphyrin unit, which allowed us to explicitly study the effects of electron-donating and electron-withdrawing substituents on catalytic performance in MOFs. Owing to the different electronic properties of ethyl, bromo, chloro, and fluoro substitutes, the molecular-level control over the chemical environment surrounding a catalytic center could be readily achieved in our MOFs. To investigate the effects of these substitutes on catalytic activity and selectivity, the oxidation of 3-methylpentane to corresponding alcohols and ketones was utilized as a model reaction. Within these five analogues of PCN-224, an extremely high turnover number of 7680 and turnover frequency of 10 240 h-1 was achieved by simply altering the substitutes on porphyrin rings. Moreover, a remarkable 99% selectivity of the tertiary alcohol over the five other possible by-products are realized. We demonstrate that this strategy can be used to efficiently screen a suitable peripheral environment around catalytic cores in MOFs for catalysis.
- Huang, Ning,Yuan, Shuai,Drake, Hannah,Yang, Xinyu,Pang, Jiandong,Qin, Junsheng,Li, Jialuo,Zhang, Yingmu,Wang, Qi,Jiang, Donglin,Zhou, Hong-Cai
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supporting information
p. 18590 - 18597
(2017/12/15)
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- Photooxygenation of alkanes by dioxygen with: P -benzoquinone derivatives with high quantum yields
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Alkanes were oxygenated by dioxygen with p-benzoquinone derivatives such as p-xyloquinone in alkanes which are used as solvents to yield the corresponding alkyl hydroperoxides, alcohols and ketones under visible light irradiation with high quantum yields (Φ = 1000, 1600%). The photooxygenation is started by hydrogen atom abstraction from alkanes by the triplet excited states of p-benzoquinone derivatives as revealed by laser-induced transient absorption spectral measurements.
- Ohkubo, Kei,Hirose, Kensaku,Fukuzumi, Shunichi
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p. 731 - 734
(2016/07/06)
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- Solvent-Free Photooxidation of Alkanes by Dioxygen with 2,3-Dichloro-5,6-dicyano-p-benzoquinone via Photoinduced Electron Transfer
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Photooxidation of alkanes by dioxygen occurred under visible light irradiation of 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) which acts as a super photooxidant. Solvent-free hydroxylation of cyclohexane and alkanes is initiated by electron transfer from alkanes to the singlet and triplet excited states of DDQ to afford the corresponding radical cations and DDQ??, as revealed by femtosecond laser-induced transient absorption measurements. Alkane radical cations readily deprotonate to produce alkyl radicals, which react with dioxygen to afford alkylperoxyl radicals. Alkylperoxyl radicals abstract hydrogen atoms from alkanes to yield alkyl hydroperoxides, accompanied by regeneration of alkyl radicals to constitute the radical chain reactions, so called autoxidation. The radical chain is terminated in the bimolecular reactions of alkylperoxyl radicals to yield the corresponding alcohols and ketones. DDQ??, produced by the photoinduced electron transfer from alkanes to the excited state of DDQ, disproportionates with protons to yield DDQH2.
- Ohkubo, Kei,Hirose, Kensaku,Fukuzumi, Shunichi
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supporting information
p. 2255 - 2259
(2016/08/30)
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- 5-SEC-BUTYL-2-(2,4-DIMETHYL-CYCLOHEX-3-ENYL)-5-METHYL-[1,3]DIOXANE AND PROCESS FOR MAKING THE SAME
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The present invention is directed to 5-sec-butyl-2-(2,4-dimethyl-cyclohex-3-enyl)-5-methyl-[1,3]dioxane and a novel process for making the same.
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Paragraph 0012; 0013
(2014/04/03)
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- 5-sec-butyl-2-(2,4-dimethyl-cyclohex-3-enyl)-5-methyl-[1,3]dioxane and process for making the same
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The present invention is directed to 5-sec-butyl-2-(2,4-dimethyl-cyclohex-3-enyl)-5-methyl-[1,3]dioxane and a novel process for making the same.
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Paragraph 0013
(2014/04/03)
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- Highly efficient redox isomerization of allylic alcohols and transfer hydrogenation of ketones and aldehydes catalyzed by ruthenium complexes
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A dicationic dichloro-bipyridine-ruthenium complex shows very high catalytic activity in redox isomerization of allylic alcohols but a relatively low one in transfer hydrogenation of ketones; surprisingly, the analogous dimethyl-bipyridine-ruthenium complex shows reverse catalytic activities in the two reactions.
- Liu, Pei Nian,Ju, Kun Dong,Lau, Chak Po
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supporting information; experimental part
p. 275 - 280
(2011/04/16)
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- Efficient and selective Al-catalyzed alcohol oxidation via oppenauer chemistry
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A highly active and selective Al-based catalytic Oppenauer (O) oxidation is reported. Quantitative and selective oxidations of a variety of benzylic, propargylic, allylic, and aliphatic primary and secondary alcohols were achieved using nitrobenzaldehyde derivatives as the oxidant and simple aluminum compounds as precatalysts. Copyright
- Graves, Christopher R.,Zeng, Bi-Shun,Nguyen, SonBinh T.
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p. 12596 - 12597
(2008/02/03)
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- FeCl3-activated oxidation of alkanes by [Os(N)O 3]-
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Although the ion [OsVIII(N)(O)3]- is a stable species and is not known to act as an oxidant for organic substrates, it is readily activated by FeCl3 in CH2Cl2/CH 3CO2H to oxidize alkanes efficiently at room temperature. The oxidation can be made catalytic by using 2,6-dichloropyridine N-oxide as the terminal oxidant. The active intermediates in stoichiometric and catalytic oxidation are proposed to be [(O)3OsVIII≡N-Fe III] and [Cl4(O)OsVIII≡N-Fe III], respectively.
- Yiu, Shek-Man,Wu, Zhi-Biao,Mak, Chi-Keung,Lau, Tai-Chu
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p. 14921 - 14929
(2007/10/03)
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- H-atom abstraction from selected C-H bonds in 2,3-dimethylpentanal, 1,4-cyclohexadiene, and 1,3,5-cycloheptatriene
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The gas-phase reactions of OH radicals with 1,4-cyclohexadiene, 1,3,5-cycloheptatriene, and 2,3-dimethylpentanal have been investigated to determine the importance of H-atom abstraction at specific positions in these molecules. Benzene was observed as a product of the reaction of OH radicals with 1,4-cyclohexadiene in 12.5 ± 1.2% yield, in good agreement with a previous study and indicating that this is the fraction of the reaction proceeding by H-atom abstraction from the allylic C-H bonds. In contrast, no formation of tropone from 1,3,5-cycloheptatriene was observed, suggesting that in this case H-atom abstraction is not important. For the reaction of OH radicals with 2,3-dimethylpentanal, formation of 3-methyl-2-pentanone was observed in 5.4 ± 1.0% yield (after correction for reaction of 3-methyl-2-pentanone with OH radicals), and this product is predicted to be formed after initial H-atom abstraction from the 2-position CH group. Acetaldehyde and 2-butanone were also observed as products, with initial yields of ～90% and ～26%, respectively, and their formation appeared to involve, at least in part, an intermediary acyl peroxy radical. Using a relative rate method, the measured rate constants for the reactions of OH radicals with 2,3-dimethylpentanal, 3-methyl-2-pentanone, and tropone are (in units of 10-12 cm3 molecule-1 s-1) 2,3-dimethylpentanal, 42 ± 7; 3-methyl-2-pentanone, 6.87 ± 0.08; and tropone, 42 ± 6.
- Tuazon, Ernesto C.,Aschmann, Sara M.,Nguyen, Marie V.,Atkinson, Roger
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p. 415 - 426
(2007/10/03)
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- Unfunctionalized, α-epimerizable nonracemic ketones and aldehydes can be accessed by crystallization-induced dynamic resolution of imines
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This paper describes an operationally simple deracemization process of aldehydes and ketones. This new crystallization-induced dynamic resolution (CIDR) protocol allows for nearly complete conversion of the racemic mixture into one enantiomer. Crystallization of imines derived from racemic ketones or aldehydes 1 and trans-(1R,2R)-1-amino-6-nitroindan-2-ol (2) afforded diastereomerically pure, crystalline imines 3. Biphasic hydrolysis of 3 then affords recovered 2 and enantiomerically enriched 1 in high yield and er (substrate, yield/ee: 2-methylcyclohexanone, 97%/92; 2-ethylhexanal, 94%/98; 2-methylcyclopentanone, 94%/98; 2-cyclohexylcyclohexanone, ND/98; 3-methyl-2-pentanone, ND/76). The scope, limitations, and industrial perspective of this process are discussed. This highly effective CIDR process is likely due to π-stacking of 2 and a hydrogen bonding of the imine with the free hydroxyl of 2 in the solid state. Copyright
- Kosmrlj, Janez,Weigel, Leland O.,Evans, David A.,Downey, C. Wade,Wu, Jimmy
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p. 3208 - 3209
(2007/10/03)
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- n-pentane carbonylation with CO on sulfated zirconia: An in situ solid-state 13C NMR study
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Using 13C CP/MAS NMR, the first evidence has been obtained for n-pentane carbonylation with carbon monoxide into C6 aldehydes, ketones and carboxylic acids on a sulfated zirconia catalyst.
- Luzgin,Stepanov,Shmachkova,Kotsarenko
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- Transformation of 1,3-, 1,4- and 1,5-diols over perfluorinated resinsulfonic acid (Nafion-H)
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The transformations of 1,3-, 1,4- and 1,5-diols over perfluorinated resinsulfonic acids (Nafion-H) were studied and correlations were examined between the structure of the investigated diols, the possible transformation directions and the catalytic properties of Nafion-H. Comparisons were also made between the catalytic properties of Nafion-H and zeolites. The characteristic transformations of 1,3-diols depend on their structure. 1,3-Propanediol undergoes dehydration via 1,2-elimination and yields oligomers via intermolecular dehydration. 1,3-Diols with an alkyl substituent on the carbon between those bearing the OH groups undergo 1,2-elimination yielding unsaturated alcohols and dienes, and give carbonyl compounds via the loss of water and hydride shifts analogous to the pinacol rearrangement. The strong acidity of Nafion-H and the lack of strong basic sites are advantageous for the latter reaction. 1,3-Diols with two substituents at this position mainly yield fragmentation products. Stereoselective cyclodehydration to the corresponding oxacycloalkanes is the characteristic transformation of 1,4- and 1,5-diols over Nafion-H.
- Bucsi,Molnar,Bartok,Olah
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p. 3319 - 3326
(2007/10/02)
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- Zinc-promoted reactions. Part 5. The behaviour of alkyl substituted 1,3-diketones
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The zinc-promoted reaction of 2,4-pentanedione and related β-dicarbonyl substrates have been investigated under a variety of conditions. The results were explained according to a general mechanism, involving ionic and nonionic pathways.
- Floris, Barbara,Luchetti, Luciana,Rosnati, Vittorio
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p. 4409 - 4418
(2007/10/02)
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- Direct Synthesis of Sulfines by Oxidation of Enethiolizable Thioketones
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Reaction of enethiolizable thioketones 2 with one equivalent of meta-chloroperoxybenzoic acid affords quantitatively the corresponding E sulfines 1.In contrast to literature expectations, direct synthesis of aliphatic sulfines by oxidation of thiocarbonyl compounds is thus possible; no divinyl disulfide 4 has been formed.
- Nocher, Anne Marie Le,Metzner, Patrick
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p. 747 - 750
(2007/10/02)
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- Recent Synthetic Developments in Thiocarbonyl Chemistry
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Direct oxidation of enethiolizable thioketones and dithioesters with a peroxycarboxylic acid affords the corresponding sulfines quantitatively.This observation stands in contrast with literature expectations, stating that this reaction would lead to divinyl disulfides.The oxidation shows a high stereoselectivity: delivery of the oxygen proceeds from the side opposite to the alkylthio group of dithioesters and from the side opposite to the more hindered substituent in the case of thioketones.The thermal stability of these sulfines was studied and a novel rearrangementwas observed.The second part of this report deals with the thio-Claisen rearrangement of precursors bearing a chiral centre adjacent to the pericyclic nucleus and its use for stereocontrol in the acyclic series.This thermally facile transposition leads to allylated dithioesters with good to excellent yields.A high diastereomeric selectivity was obtained in a number of cases involving either a steric effect with alkyl groups on the chiral centre or a noteworthy electronic effect when this centre bears a heteroatomic group.It was also carried out in the homochiral series.A favoured conformation and approach model is proposed to explain the formation of syn isomers.
- Metzner, Patrick
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- Stereoselective synthesis of gem-disubstituted cyclopropanes from gem-dibromocyclopropanes
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The title reaction is realized by utilizing an intramolecular alkylation reaction of zincate carbenoids followed by a Pd (0)-catalyzed coupling reaction with acyl, aryl, and alkenyl halides.
- Harada,Katsuhira,Hattori,Oku
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p. 6039 - 6040
(2007/10/02)
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- Dianions Derived from α-Halo Acids. The Darzens Condensation Revisited
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The dianions of α-halo carboxylic acids are readily generated by the addition of the acids to 2 equiv of lithium diisopropylamide at low temperatures.When the mixture warms to room temperature dimeric products are formed.When aldehydes and ketones were added to the cooled solutions of the dianions and the reaction mixtures were allowed to warm to room temperature, followed by acid quench, glycidic acids were formed.The glycidic acids, per se, were often too unstable to be isolated and purified but could be analyzed by conversion to their methyl esters withdiazomethane.When the reactions were quenched prematurely, α-chloro-β-hydroxy carboxylic acids were isolated.Homologated aldehydes and ketones were obtained from the glycidic acids by catalytic and thermal decarboxylation methods.
- Johnson, Carl R.,Bade, Thomas R.
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p. 1205 - 1212
(2007/10/02)
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- Thermochemical Studies of Carbonyl Reactions. 2. Steric Effects in Acetal and Ketal Hydrolysis
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A calorimetric determination of the enthalpies of hydrolysis of a series of alkyl-substituted dimethyl acetals is reported.These data are critically compared with the enthalpies of hydrolysis from an analogous set of aliphatic dimethyl ketals derived from 2-alkanones.The acetals exhibit a significantly attenuated range in their enthalpies of hydrolysis relative to that for ketal hydrolysis.The free energies of acetal formation in solution were modeled by measurements of the corresponding free energies of hemiacetal formation from the aldehydes in neutral methanol.The observed free-energy differences are satisfactorily correlated with the Taft Es steric substituent constant scale, but the corresponding acetal enthalpy data vary in a complex manner.The role of entropy in determining kinetic and equilibrium steric effects in a variety of other systems is discussed.Preliminary molecular mechanics calculations on these systems indicate the importance of bond angle bending in evaluating the torsional potential at a carbonyl group.Many of the compounds were found to possess several conformations having comparable energies.
- Wiberg, Kenneth B.,Squires, Robert R.
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p. 4473 - 4478
(2007/10/02)
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- REACTIVITE DES DERIVES ORGANOCUIVREUX VIS-A-VIS DES ALDEHYDES αβ-ETHYLENIQUES
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Secondary lithium dialkylcuprates react with αβ-ethylenic aldehydes to give a mixture of 1,2 and 1,4 addition products.Only 1,2 addition products are obtained with allylic and acetylenic cuprates whereas homallylic, phenyl and vinylic cuprates give 1,4 addition products.The 1,4/1,2 ratio also depends on the nature of the metal in the cuprate (Mg or Li).Thus chloromagnesium dimethyl cuprate, in THF, is the most favorable compound to give the 1,4 addition product.
- Chuit, C.,Foulon, J. P.,Normant, J. F.
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p. 1385 - 1389
(2007/10/02)
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- The Allopolarization Principle and its Applications, VI. The Alkylation of Enolate Anions: Polarity and Regioselectivity
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The O/C methylation ratio in the reaction of sodium enolates with dimethylsulfate depends on the polar (electronic) effect of substituents.The relative ?-charge density Px/y = lx/ly can be used as a measure for the polarity of ambifunctional anions; in case of enolate anions PO/C = lO/lC.The change of the regioselectivity Sf = log QO/QC in the alkylation of enolates is a function of a change in the polarity PO/C; ΔSf=f(ΔPx/y).The polar effect of substituents influences the charge control during the alkylation process via a change of the polarity of the enolate system: The higher the polarity of the anion, the stronger the charge control and the higher the yield of enol ether (O-alkylation). - Keywords: Alkylation, Enolate Anions
- Gompper, Rudolf,Vogt, Hans-Hubert,Wagner, Hans-Ulrich
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p. 1644 - 1652
(2007/10/02)
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- Desamination of β- and γ-Amino Alcohols
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Nitrous acid deaminations of the β-amino alcohols 2 and 12 afford 1,2 diols as well as ketones by pinacolic rearrangement.Both types of products arise with predominant inversion of configuration.Stereochemical studies and isotopic labeling reveal that formation of the diols involves an oxygen shift, presumably via oxirane intermediates.Deamination of the γ-amino alcohol 37 induces, in part, sequential rearrangements to give products also obtained from 12, but in different proportions and enantiomeric purities.Conformational control provides a reasonable explanation of our results.
- Guenther, Bernd-Rainer,Kirmse, Wolfgang
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p. 518 - 532
(2007/10/02)
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- ACTION DES DIALKYLCUPRATES DE LITHIUM SUR LES ALDEHYDES α,β-ETHYLENIQUES
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Nearly exclusive 1-4 addition products are obtained by action of lithium dialkylcuprates with α,β-ethylenic aldehydes.Non polar solvents and low temperatures favor this reaction.Only α,β-ethylenic aldehydes having a trisubstituted double bond give a relatively important proportion of 1-2 addition product.
- Chuit, C.,Foulon, J. P.,Normant, J. F.
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p. 2305 - 2310
(2007/10/02)
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- Cardioglycoside derivatives of the strophanthidin type, a process for their manufacture and medicinal preparations containing these compounds
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Cyclic acetals or ketals of cardioglycosides derived from k-strophanthidin or strophanthidol are more readily absorbed by the stomach and intestine than the parent cardioglycoside. The acetals are produced by reaction of the parent cardioglycoside, e.g., strophanthidindigitoxide, with an aldehyde or ketone, or the corresponding acetal or ketal, in the presence of an acid condensation catalyst, to produce the k-strophanthidin derivative optionally followed by reduction to the strophanthidiol derivative.
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