90-42-6Relevant articles and documents
The Silicon-Hydrogen Exchange Reaction: A Catalytic σ-Bond Metathesis Approach to the Enantioselective Synthesis of Enol Silanes
Zhou, Hui,Bae, Han Yong,Leutzsch, Markus,Kennemur, Jennifer L.,Bécart, Diane,List, Benjamin
supporting information, p. 13695 - 13700 (2020/08/24)
The use of chiral enol silanes in fundamental transformations such as Mukaiyama aldol, Michael, and Mannich reactions as well as Saegusa-Ito dehydrogenations has enabled the chemical synthesis of enantiopure natural products and valuable pharmaceuticals. However, accessing these intermediates in high enantiopurity has generally required the use of either stoichiometric chiral precursors or stoichiometric chiral reagents. We now describe a catalytic approach in which strongly acidic and confined imidodiphosphorimidates (IDPi) catalyze highly enantioselective interconversions of ketones and enol silanes. These "silicon-hydrogen exchange reactions"enable access to enantiopure enol silanes via tautomerizing σ-bond metatheses, either in a deprotosilylative desymmetrization of ketones with allyl silanes as the silicon source or in a protodesilylative kinetic resolution of racemic enol silanes with a carboxylic acid as the silyl acceptor.
Pd nanoparticles/polyoxometalate-ionic liquid composites on SiO2 as multifunctional catalysts for efficient production of ketones from diaryl ethers
Zhang, Zhanrong,Liu, Mingyang,Song, Jinliang,Liu, Huizhen,Xie, Zhenbing,Liu, Shuaishuai,Meng, Qinglei,Zhang, Pei,Han, Buxing
, p. 4865 - 4869 (2018/11/21)
The high stability of C-O bonds in diaryl ethers limits the valorization of lignin. Herein, reductive hydrolysis of C-O bonds in diaryl ethers was achieved over Pd nanoparticle/polyoxometalate-ionic liquid composite supported on SiO2 (Pd/H2[POM-IL]@SiO2) in water, selectively yielding ketones free from their alcohol counterparts in unprecedentedly high yields (>80%).
Conversion of lignin model compounds under mild conditions in pseudo-homogeneous systems
Chen, Lu,Xin, Jiayu,Ni, Lingli,Dong, Huixian,Yan, Dongxia,Lu, Xingmei,Zhang, Suojiang
supporting information, p. 2341 - 2352 (2016/05/19)
To produce basic chemicals from lignin, depolymerization and removal of oxygen from lignin through C-O cleavage and hydrodeoxygenation (HDO) are crucial steps. In this study, a novel, pseudo-homogeneous catalyst system, consisting of uniformly stabilized noble metal nanoparticles (NPs) in ionic liquids is developed for the selective reductive cleavage of C-O and HDO. Phenol and guaiacol as lignin monomer model compounds are investigated to gain an insight into the possible HDO pathway, meanwhile, dimeric model compounds such as diphenyl ether and benzyl phenyl ether are studied for the cleavage of C-O bonds between aromatic units. Four types of NPs including Pd, Pt, Rh and Ru were synthesized in situ and well distributed in ILs without aggregation. These catalytic systems displayed almost 100% conversion for various monomeric and dimeric lignin model compounds at 130°C and were recycled several times without loss of activity. The catalytic selectivity of metals for HDO/C-O cleavage normally decreases in the order of Pt > Rh ～ Ru ? Pd, which is similar to the order of NP size, Pd ? Pt > Rh ～ Ru. With a mean diameter of 5.6 nm, Pt NPs in [Bmim]PF6 are identified as the best catalytic system for the transformation of lignin monomeric and dimeric model compounds with an almost 100% conversion and maximum 97% selectivity.
Promising Ni/Al-SBA-15 catalysts for hydrodeoxygenation of dibenzofuran into fuel grade hydrocarbons: Synergetic effect of Ni and Al-SBA-15 support
Gbadamasi, Sharafadeen,Ali, Tammar Hussein,Voon, Lee Hwei,Atta, Abdulazeez Yusuf,Sudarsanam, Putla,Bhargava, Suresh K.,Abd Hamid, Sharifah Bee
, p. 25992 - 26002 (2016/03/25)
This work has been undertaken with the aim of designing promising noble-metal-free catalysts for efficient hydrodeoxygenation (HDO) of dibenzofuran (DBF) into fuel grade hydrocarbons. For this, various Ni/Al-SBA-15 catalysts with different Si/Al (50, 60, 70 and 80) mole ratios were synthesized and their catalytic performance was tested for HDO of DBF in a batch reactor. The catalysts were systematically characterized using XRD, N2-adsorption-desorption, Raman, H2-TPR, NH3-TPD, XRF, and FESEM techniques. The activity results showed that the HDO of DBF proceeds via hydrogenation of benzene on the Ni sites followed by cleavage of C-O bonds on the acidic sites of the catalyst to yield unsaturated hydrocarbons. Further hydrogenation of unsaturated hydrocarbons on the Ni sites gives bicyclohexane as the major product. Remarkably, a 100% DBF conversion was found for all the catalysts except for Ni/SBA-15 and Ni/Al-SBA-15(80) (Si/Al mole ratio = 80) catalysts, which showed 97.97 and 99.31%, respectively. A significant observation noticed in this study is that the incorporation of Al into Ni/SBA-15 results in an outstanding improvement in the selectivity of the bicyclohexane product. Among the catalysts tested, the Ni/Al-SBA-15(50) (Si/Al mole ratio = 50) catalyst showed the highest efficiency, with superior selectivity of ～87% for bicyclohexane and ～96% degree of deoxygenation at 10 MPa, 260 °C and 5 h. The obtained structure-activity results reveal the synergetic effect of Ni and support in HDO of DBF reaction: the concentration of acidic sites has a significant effect on the selectivity of the desired products.
Effective hydrodeoxygenation of dibenzofuran by a bimetallic catalyst in water
Dong, Peng,Lu, Guo-Ping,Cai, Chun
, p. 1605 - 1609 (2016/02/19)
Effective hydrodeoxygenation (HDO) of dibenzofuran (DBF) catalyzed by a bimetallic nickel/platinum (Ni/Pt) catalyst in water was demonstrated at 200 °C and 1.2 MPa hydrogen (H2) pressure. The bimetallic catalysts prepared by a wet chemical method exhibit prominent activity that overcomes the limitations of use of a single Ni or Pt metal catalyst. The yield of HDO products can be up to 90%. Reaction results indicate that the conversion of DBF was affected by the reaction temperature and H2 pressure. The deoxygenation selectivity was strongly dependent on reaction temperature. The reaction pathway is also proposed.
Cu/Mg/Al/Zr non-noble metal catalysts for o-phenylphenol synthesis
Zeng, Yongping,Zhang, Tianchi,Xu, Yueyang,Hu, Peili,Ye, Ting,Jia, Zhehua,Ju, Shengui
, p. 6737 - 6746 (2016/02/03)
Cu/Mg/Al/Zr hydrotalcite-like precursors with Zr4+:(Al3+ + Zr4+) atomic ratios between 0 and 1 were prepared by co-precipitation methods. The precursors were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric (TG) analysis and Fourier transform infrared spectroscopy (FT-IR). The results confirmed that well-defined layered double hydroxides (LDH) can be synthesized when the added Zr content is less than 0.25 in terms of Zr4+/(Al3+ + Zr4+) atomic ratio. The catalysts of Cu/Zn/Al/Zr mixed oxides can be obtained via thermal decomposition of hydroxide precursors, and can be used in dehydrogenation of 2-(1-cyclohexenyl) cyclohexanone (CHCH) to ortho-phenylphenol (OPP). Copper particles inside the catalyst act as active sites for dehydrogenation. Transmission electron microscopy (TEM), XRD, N2O chemisorption and N2 adsorption-desorption were performed to investigate the effect of Zr content on determining the copper particle size. Based on the catalytic performance test, it was concluded that the conversion of CHCH depends on the copper particle size of these catalysts.
Highly Selective Hydrogenation of Aromatic Ketones and Phenols Enabled by Cyclic (Amino)(alkyl)carbene Rhodium Complexes
Wei, Yu,Rao, Bin,Cong, Xuefeng,Zeng, Xiaoming
supporting information, p. 9250 - 9253 (2015/08/11)
Air-stable Rh complexes ligated by strongly σ-donating cyclic (amino)(alkyl)carbenes (CAACs) show unique catalytic activity for the selective hydrogenation of aromatic ketones and phenols by reducing the aryl groups. The use of CAAC ligands is essential for achieving high selectivity and conversion. This method is characterized by its good compatibility with unsaturated ketones, esters, carboxylic acids, amides, and amino acids and is scalable without detriment to its efficiency.
Clean borrowing hydrogen methodology using hydrotalcite supported copper catalyst
Dixit, Manish,Mishra, Manish,Joshi, Pradyuman A.,Shah, Dinesh O.
, p. 80 - 83 (2013/05/09)
The catalytic activity of Mg-Al hydrotalcite supported copper catalyst was investigated for clean CC and CN bond forming reactions using alcohols as alkylating agent via borrowing hydrogen methodology. The catalyst showed excellent conversion of ketone and amine substrates (71-99%) to alkylated products with high selectivity in alkylation reactions.
A boron-based synthesis of the natural product (+)-trans- dihydrolycoricidine
Poe, Sarah L.,Morken, James P.
supporting information; experimental part, p. 4189 - 4192 (2011/06/20)
Diastereoselective diboration results in the highly selective 1,4-dihydroxylation of chiral cyclohexadienes (see scheme). Together with the catalytic enantioselective conjugate allylboration, the diene diboration facilitates the asymmetric synthesis of the cytotoxic agent (+)-trans- dihydrolycoricidine (1). pin=pinacol. Copyright
Catalytic asymmetric hydrolysis: Asymmetric hydrolytic protonation of enol esters catalyzed by phase-transfer catalysts
Yamamoto, Eiji,Nagai, Ayano,Hamasaki, Akiyuki,Tokunaga, Makoto
, p. 7178 - 7182 (2011/08/03)
Like an enzyme: Asymmetric hydrolysis of enol esters is accomplished by chiral phase-transfer catalysts under biphasic base hydrolysis conditions. Stoichiometric reactions support the generation of a well-organized chiral ammonium hydroxide species (Q+OH-). Copyright
