15164-44-0Relevant academic research and scientific papers
N-Doped carbon encapsulated molybdenum carbide as an efficient catalyst for oxidant-free dehydrogenation of alcohols
Leng, Yan,Li, Jingjing,Zhang, Chenjun,Jiang, Pingping,Li, Yue,Jiang, Yuchen,Du, Shengyu
, p. 17580 - 17588 (2017)
We report molybdenum carbide (Mo2C) encapsulated in N-doped carbon as an efficient and stable catalyst for oxidant-free dehydrogenation of alcohols, prepared by anion exchange of H3PMo12O40 (PMo) with an ionic copolymer (DIM-AN) of dicationic imidazole ionic liquid and acrylonitrile, followed by a two-step carbonization at 400 °C in air and 800 °C in Ar. The synthesized catalyst (PMo@DIM-AN400/800) exhibits outstanding catalytic activity and selectivity for dehydrogenation of various alcohols under oxidant-free conditions and can be steadily reused at least five times for dehydrogenation of benzyl alcohol without changing its crystalline structure. The characterizations and comparative experimental results demonstrate that the active sites for dehydrogenation stem from the Mo2C, as well as the abundant N atoms in the carbon shell, which contribute to the enhancement of catalytic performance. The strategy for the preparation of such N-doped carbon encapsulated Mo2C using polyoxometalate-based ionic hybrids as precursors may open up new opportunities for exploring more transition-metal carbides for more catalytic applications.
Solid-Phase Synthesis of Biaryls via the Stille Reaction
Forman, Frank W.,Sucholeiki, Irving
, p. 523 - 528 (1995)
The solid-phase synthesis of biphenyls by heterogenous cross-coupling of trialkylphenylstannanes with aryl electrophiles is described.Tributylphenyltin attached by an amide bond to the Rink amide resin undergoes palladium-catalyzed coupling with aryl triflates and aryl iodides to produce after acid cleavage 4-biphenylacetamide in 3-15percent yield. 4-Iodophenylacetic acid attached to the Rink amide resin by an amide bond also undergoes heterogeneous palladium-catalyzed coupling with trialkylphenyltins to give after acid cleavage of the support 4-biphenylacetamide in 21-33percent yield. 4-Iodobenzylbromide was then attached to the photocleavable (+/-)-2-methoxy-5--1-oxopropyl>phenylacetamide (NpSSMpact) resin through the formation of a thioether bond.Both substituted and unsubstituted trimethylphenyltins were shown to undergo palladium-catalyzed Stille coupling with the resin bound aryl iodide to give after photolytic cleavage biphenyls containing no residual amide, carboxylic acid, or alcohol appendages.
Copper(II) Complexes of 2,2:6,2-Terpyridine Derivatives for Catalytic Aerobic Alcohol Oxidations - Observation of Mixed-Valence CuICuII Assembles
Zhang, Guoqi,Liu,Yang, Chengxiong,Li, Li,Golen, James A.,Rheingold, Arnold L.
, p. 939 - 947 (2015)
The reactions of copper(II) salts with simple terpyridine (tpy) ligands gave mononuclear monoligand complexes 1-3, of which two new structures have been characterized by X-ray crystallography. These complexes were applied as catalysts for the oxidation of benzylic alcohol to benzaldehyde in air in the presence of the radical 2,2,6,6-tetramethylpiperidinyl-1-oxyl (TEMPO). Copper complexes 1 and 2 are efficient catalysts for the reactions in water at 70 C with 4-dimethylaminopyridine (DMAP) as an extra base. The influence of TEMPO on the formation of new reactive intermediates during the catalytic reactions was tentatively investigated by introducing TEMPO into the reaction solutions of tpy derivatives with copper dichloride. Two new complexes with interesting solid-state structures resulting from these reactions have been isolated and characterized. The coordination reactions in the presence of TEMPO led to new mixed-valence CuICuII supramolecular assembles (4 and 5), although they adopt either discrete complex or 1D polymeric structures. Further catalytic studies indicated that the mixed-valence assembles 4 and 5 displayed higher catalytic activity than those of the mononuclear complexes under milder conditions. The relationship between the molecular structures of diverse copper complexes and their reactivity is discussed on the basis of the results obtained.
Influence of catalyst nuclearity on copper-catalyzed aerobic alcohol oxidation
Krittametaporn, Nuttaporn,Chantarojsiri, Teera,Virachotikul, Arnut,Phomphrai, Khamphee,Kuwamura, Naoto,Kojima, Tatsuhiro,Konno, Takumi,Sangtrirutnugul, Preeyanuch
, p. 682 - 689 (2020)
Reactions of CuX with the bis(triazolyl) ligand Hbtm [bis(1-benzyl-1H-1,2,3-triazol-4-yl)phenylmethanol] in CH2Cl2 afforded trinuclear copper(ii) complexes with a core structure (μ-X)Cu3(μ-κ3-N,O,N-btm)3(L)2+ [X = Cl, L = CH3OH (1); X = Br, L = H2O (2)], while a similar reaction of [Cu(CH3CN)4](PF6) with the mono(triazolyl) ligand HPhtm [(1-benzyl-1H-1,2,3-triazol-4-yl)diphenylmethanol] resulted in the mononuclear complex [Cu(κ2-N,O-Phtm)(κ2-N,O-HPhtm)(κ1-N-HPhtm)][PF6] (3). The structural characterization of these complexes was made by single-crystal X-ray crystallography in combination with elemental and ESI mass analyses. Catalytic studies toward aerobic oxidation of benzyl alcohol to benzaldehyde revealed that the trinuclear 1 and 2 exhibited higher activities than the mononuclear 3 in both CH3CN and EtOH/H2O solvent systems.
Practical and efficient ipso-iodination of arylboronic acids via KF/I2 system
Tramutola, Francesco,Chiummiento, Lucia,Funicello, Maria,Lupattelli, Paolo
, p. 1122 - 1123 (2015)
A facile and effective iododeboronation of variously substituted aryl and heteroarylboronic acids through activation and subsequent ipso-introduction of iodine is presented. The use of KF and I2 at 80 °C in 1,4-dioxane furnishes iodinated compounds in high yields.
Synthesis and aggregation properties of boron-dipyrromethene dyes conjugated with guanine units
Li, Fen,Zhang, Yongjie,Zhou, Lina,Zhang, Xin,Chen, Zhijian
, p. 944 - 952 (2018)
Two boron-dipyrromethene dyes bearing a conjugated guanine unit (G-BODIPYs) 1 and 2 were synthesized and fully characterized. The self-assembly properties of these dyes were investigated by X-ray crystallography, 1H NMR and UV-vis spectroscopy. As revealed by X-ray crystal structure studies, G-BODIPY 1 self-assembled into ribbon-like structures due to the intermolecular hydrogen bonding and π-π stacking interaction. Concentration-dependent 1H NMR experiments confirmed the formation of hydrogen bonds of the guanine units in solution for both dye 1 and 2. In the presence of K+, the characteristic signals for the formation of cyclic G-quadruplex structures were observed in the 1H NMR study. Aggregation of G-BODIPY dyes was further monitored by UV-vis absorption spectroscopy by varying the solvent polarity and temperature. H-type aggregates of dye 1, which was characterized by a new hypsochromically shifted absorption band with λmax = 461 nm, was obtained. In the presence of K+, the enhancement of stability was observed for the H-aggregates of dye 1.
Ti3C2/TiO2 nanowires with excellent photocatalytic performance for selective oxidation of aromatic alcohols to aldehydes
Xu, Chong,Yang, Fan,Deng, Bijian,Zhuang, Yue,Li, Dingyao,Liu, Baocheng,Yang, Wang,Li, Yongfeng
, p. 1 - 12 (2020)
The Ti3C2/TiO2 nanowires photocatalyst is synthesized by in situ growth through a facile hydrothermal method and mild chemical processes for the first time. The Ti3C2/TiO2-0.7 exhibits high photocatalytic activity for selective oxidation of aromatic alcohols to aldehydes under visible light irradiation. The 92% benzyl alcohol conversion and almost 99% selectivity is observed for the Ti3C2/TiO2-0.7 photocatalyst, higher than that of P25 and TiO2 nanowires. Results reveal that the photocatalytic activity of this photocatalyst is mainly attributed to the introduction of Ti3C2, which results in the narrowed energy band gap by altering the position of CB and VB of TiO2 and the enhanced light-harvesting ability. In our design, a Schottky barrier is established between Ti3C2 and TiO2 nanowires to improve the separation efficiency of photogenerated electrons and holes. Significantly, the feasible reaction mechanism of Ti3C2/TiO2 nanowires photocatalyst under visible light is proposed.
Kinetics and oxidation of substituted benzyl alcohols by phenyliodoso acetate
Girija,Aruna
, p. 264 - 268 (2011)
Oxidation of benzyl alcohol and some meta- and para- substituted alcohols by phenyliodoso acetate (PIA) in t-butyl alcohol-water medium (50:50) leads to the formation of corresponding benzaldehyde. The stoichiometry of the reaction was found to be 1:1. The reaction was first order each in substrate and oxidant concentrations. This reaction was studied at four different temperatures and the activation parameters were calculated. Correlation analysis was carried out using Taft's and Swain's dual substituent parameter (DSP) equation. The rate data of meta- compounds showed good correlation with (F,R) values, para-substituted benzyl alcohols showed good correlation with σIσR + A suitable mechanism has been proposed.
Synthesis of a single-molecule nanotruck
Sasaki, Takashi,Morin, Jean-Fran?ois,Lu, Meng,Tour, James M.
, p. 5817 - 5820 (2007)
We report the synthesis of a new nanovehicle, a porphyrin-based nanotruck. The porphyrin inner core was designed for possible transportation of metals and small molecules across a surface.
Hypervalent Activation as a Key Step for Dehydrogenative ortho C-C Coupling of Iodoarenes
Wu, Yichen,Arenas, Ismael,Broomfield, Lewis Marc,Martin, Eddy,Shafir, Alexandr
, p. 18779 - 18784 (2015)
Building on earlier results, a direct metal-free α- arylation of substituted cyclic 1,3-diones using ArI(O2CCF3)2 reagents has been developed; unlike other arylative approaches, the arylated products retain the iodine substituent ortho to the newly formed C-C bond. The mechanism is explored by using DFT calculations, which show a vanishingly small activation barrier for the C-C bond-forming step. In fact, taking advantage of an efficient in situ hypervalent activation, the iodoarenes are shown to undergo a cross- dehydrogenative C-C coupling at the C-H ortho to the iodine. When Oxone is used as terminal oxidant, the process is found to benefit from a rapid initial formation of the hypervalent ArI(OR)2 species and the sulfate-accelerated final coupling with a ketone. This method complements the ipso selectivity obtained in the metal-catalyzed α-arylation of carbonyl compounds.
