- Copper-catalyzed benzylic oxidation of C(sp3)-H bonds
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A selective oxidation of benzylic C(sp3)-H bonds to C(sp 3)-O bonds catalyzed by copper complexes of quinoline-imine ligands was developed with peresters as oxidants under mild reaction conditions, which converted benzylic methylenes directly into benzylic alcohols and esters by means of direct C-H bond functionalization.
- Zhang, Bo,Zhu, Shou-Fei,Zhou, Qi-Lin
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supporting information
p. 2033 - 2037
(2013/03/13)
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- Photocatalytic degradation of polycyclic aromatic hydrocarbons in GaN:ZnO solid solution-assisted process: Direct hole oxidation mechanism
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GaN:ZnO exhibits excellent activity for the photodegradation of PAHs, and the activity can be obviously improved by loading Pt. The degradation of PAHs in the system of GaN:ZnO is induced by the formation of holes. The holes generated then interact with PAHs to produce PAHs+, which is active enough to react with O2.
- Kou, Jiahui,Li, Zhaosheng,Guo, Yong,Gao, Jun,Yang, Ming,Zou, Zhigang
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experimental part
p. 48 - 54
(2010/10/01)
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- From surface-inspired oxovanadium silsesquioxane models to active catalysts for the oxidation of alcohols with O2-The cinnamic acid/ metavanadate system
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Silsesquioxane dioxovanadate(V) complexes were investigated with respect to their potential as a catalyst for the oxidative dehydrogenation of alcohols with O2 as an oxidant. The turnover frequencies determined were comparatively low, but during the oxidation of cinnamic alcohol an increase in activity was observed in the course of the process, which was inspected more closely. It turned out that during the oxidation of cinnamic alcohol, not only was the aldehyde formed but also cinnamic acid, which in turn reacts with the silsesquioxane complex employed to give NBu4- [O2V(O 2CC2H2Ph)2], which can also be obtained from NBu4VO3 and cinnamic acid and represents a far more active catalyst, not only for cinnamic alcohol but also for other activated alcohols and hydrocarbons. The rate-determining step of the conversion corresponds to an hydrogen-atom abstraction from the C-H units, as shown by the determination of the kinetic isotope effect in case of 9-hydroxyfluorene, and the reoxidation of the reduced catalyst proceeds via a peroxo intermediate, which is also capable of oxidizing one alcohol equivalent. Furthermore the influence of the organic residues at the carboxylate ligands on the catalyst performance was investigated, which showed that the activity increases with decreasing pKs value. Moreover, it was found that during the oxidation the catalyst slowly decomposes, but can be regenerated by addition of excessive carboxylic acid.
- Ohde, Christian,Limberg, Christian
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supporting information; scheme or table
p. 6892 - 6899
(2010/08/06)
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- Reaction of Aluminium Hydride-Triethylamine Complex with Selected Organic Compounds Containing Representative Functional Groups
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The addition of triethylamine to a solution of aluminium hydride in tetrahydrofuran (THF), which was prepared by the addition of a calculated amount of hydrogen chloride in diethyl ether to solutions of sodium aluminium hydride in THF, provides very stable solutions of aluminium hydride-triethylamine complex (AHTEA).The reducing power of AHTEA complex in tetrahydrofuran toward 59 selected organic compounds containing representative functional groups under practical conditions (tetrahydrofuran, room temperature, the quantitative amount of reagent to compound) has been investigated.In this way, we have established that quantitative reduction of various organic functionalities can be readily achieved using the calculated quantity of AHTEA to avoid the use of excess reagent.This permits ready use of the aluminium hydride reagent in organic synthesis with high convenience and efficiency, with the possibility of an improved selectivity than that of aluminium hydride itself in tetrahydrofuran.
- Cha, Jin Soon,Brown, Herbert C.
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p. 3974 - 3979
(2007/10/02)
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- Photochemistry of anthracene in water
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Photolysis of anthracene (350 nm) in aerated water yields endoperoxide and 9,10-anthraquinone as the major primary photoproducts. Photolysis of anthracene in oxygen-deficient aqueous solutions yields the three isomers of 10,10'-dihydroxy-9,9',10,10'-tetrahydro-9,9'-bianthryl as the primary photoproduct. Involvement of a cation radical mechanism is suggested.
- Sigman,Zingg,Pagni,Burns
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p. 5737 - 5740
(2007/10/02)
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- ELECTROCHEMISTRY AT ANTHRACENE CRYSTAL/AQUEOUS NO2-, NO3- SOLUTION INTERFACE
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Holes (radical cations) were injected into one face of an anthracene crystal slab and discharged at the other face, which was in contact with a neutral aqueous solution containing 1 M NO3- or NO2-.Hole current densities (J) of up to 700 μAcm-2 generated a variety of surface oxidation products including anthraquinone, 9-nitroanthracene (9NA), oxanthrone, anthrone, bianthronyl (BA), and 9,10-dinitroanthracene with both NO3- and NO2- solutions.The amount of BA and 9NA increased as J2.With increasing NO3- concentration, the amount of 9NA produced increased, while that of BA decreased.It was concluded that 9NA is made by cooperation of two holes on adjoining molecules at defect sites.
- Leong, Baldwin,Pope, Martin,Steigman, Joseph
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p. 2506 - 2511
(2007/10/02)
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- Selective Reductions. 36. Reaction of Lithium 9-Boratabicyclononane with Selected Organic Compounds Containing Representative Functional Groups
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The approximate rates, stoichiometry, and products of the reaction of lithium 9-boratabicyclononane with selected organic compounds containing representative functional groups were examined under standard conditions (tetrahydrofuran, room temperature) in order to explore the reducing characteristics of this reagent and to establish the utility of this reagent as a selective reducing agent.Primary alcohols, phenols, and thiols evolve hydrogen rapidly and quantitatively.However, the reaction of 3-hexanol and 3-ethyl-3-pentanol is very slow. n-Hexylamine is inert to this reagent.Aldehydes and ketones are reduced rapidly and quantitatively to the corresponding alcohols.Even the highly hindered ketone, 2,2,4,4-tetramethyl-3-pentanone, is reduced within 30min.Reduction of camphor gives 91percent isoborneol and 9percent borneol, respectively.Cinnamaldehyde is rapidly reduced to the cinnamyl alcohol quantitatively without attacking the double bond.Carboxylic acids liberate hydrogen rapidly and quantitatively, but further reduction is very slow.Anhydrides consume 2 equiv of hydride without further hydride uptake, corresponding to reduction to an equimolar mixture of carboxylic acid and alcohol.Acid chlorides, esters, and lactones are rapidly reduced to the corresponding alcohols.Epoxides utilize 1 equiv of hydride at a moderate rate.In the case of unsymmetrical epoxides, the Markovnikov ring opening is predominant.Acetal, ketal, and ortho esters are inert to this reagent.Primary amides liberate hydrogen slowly.Caproamide undergoes slow reduction, but benzamide is not reduced.Tertiary amides consume 2 equiv of hydride slowly, undergoing reduction to the corresponding amines.Benzonitrile is reduced to the amine stage within 12 h; however, an aliphatic nitrile, capronitrile, is reduced only sluggishly. 1-Nitropropane rapidly liberates 1 equiv of hydrogen, but further reduction is very slow.Nitrobenzene utilizes 2.5 equiv of hydride, 1 for hydrogen evolution and 1.5 for reduction.Azobenzene is inert and azoxybenzene is reduced very sluggishly.Cyclohexanone oxime rapidly evolves 1 equiv of hydrogen, but no reduction is observed.Phenyl isocyanate consumes only 1 equiv of hydride to proceed to the formanilide stage.Pyridine is reduced very slowly.However, pyridine N-oxide undergoes rapid reduction with this reagent.Disulfides are rapidly reduced to the thiol stage, whereas, sulfoxides, sulfones, sulfonic acids, and sulfides are inert to this reagent.Cyclohexyl tosylate is also inert, but n-octyl tosylate undergoes reduction within 3.0 h.This hydride is inert to a typical n-alkyl chloride but reacts moderately with n-alkyl bromide and rapidly with an n-alkyl iodide.A secondary alkyl bromide is almost inert to this hydride.
- Brown, Herbert C.,Mathew, C. Poonoose,Pyun, Chongsuh,Son, Jong Chan,Yoon, Nung Min
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p. 3091 - 3097
(2007/10/02)
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