123-31-9Relevant articles and documents
Synthesis of renewable C-C cyclic compounds and high-density biofuels using 5-hydromethylfurfural as a reactant
Cai, Taimei,Deng, Qiang,Deng, Shuguang,Gao, Rui,Peng, Hailong,Wang, Jun,Zeng, Zheling,Zhong, Jin,Zou, Ji-Jun
, p. 2468 - 2473 (2020)
The major challenge in the synthesis of high-density biofuels is to identify the bio-based source for C-C cyclic compounds and C-C coupling reactions with a suitable selectivity. Herein, we selectively synthesize 1,2,4-benzenetriol (BTO) with a yield of 51.4% from cellulose-derived 5-hydromethylfurfural via a ring-rearrangement reaction. The cellulose-derived route is a more meaningful route for the C-C cyclic compounds compared to the traditional hemicellulose- and lignin-derived routes. Furthermore, BTO is very easily dimerized via a C-C oxidative coupling reaction, showing a yield of 94.4% and selectivity of nearly 100% under environmentally friendly reaction conditions. After hydrodeoxygenation, bicyclohexane is obtained with a yield of 87.4%. This work not only provides a promising route to produce C-C cyclic fine compounds based on a cellulose-derived route, but also shows a highly efficient synthesis route for high-density biofuels via the C-C oxidative coupling reaction.
Reactions of 1,4-benzoquinones with s2 reducing centers
Yang, Zhiyong,Gould, Edwin S.
, p. 2219 - 2223 (2003)
Aqueous solutions of Sn(II) and Ge(II) (in chloride media) and In(I) (in perchlorate media) react quantitatively with 1,4-benzoquinone and its 2,5-(OH)2 and 2,5-Cl2-3,6-(OH)2 derivatives, reducing the oxo-functions to 1,4-(OH)2. For Sn(II) and Ge(II), reaction is accelerated by incorporation of 2,5-(OH)2 substituents and by chloroanation of the s2 center. The most reactive reducing Sn(II) species are SnCl3- for benzoquinone and dihydroxyquinone but SnCl2(aq)x for the dichloroquinone. Reductions by Ge(II) proceed mainly through a species (probably GeCl 42-) having one more chloride than the predominant form. The activated complex for the (OH)2bzq-Ge(II) reaction features two germanium centers, only one of which is involved in the reduction act. Reductions of these quinones by In(I) proceed 102-103 times as rapidly as those by Sn(II) and Ge(II) and are not accelerated by hydroxylation of the quinone ring. The Royal Society of Chemistry 2003.
Oxygen-vacancy-promoted catalytic wet air oxidation of phenol from MnO: X-CeO2
Ma, Changjian,Wen, Yaoyao,Yue, Qingqing,Li, Anqi,Fu, Jile,Zhang, Nouwei,Gai, Hengjun,Zheng, Jinbao,Chen, Bing H.
, p. 27079 - 27088 (2017)
Catalytic oxidation can be effectively promoted by the presence of oxygen vacancies on the catalyst surface. In this study, the effect of oxygen vacancies on the catalytic wet air oxidation (CWAO) of phenol was investigated with CeO2 and MnOx-CeO2 as catalysts. CeO2 and MnOx-CeO2 catalysts with different amounts of oxygen vacancies were obtained via hydrothermal methods and applied for the CWAO of phenol. It was found that CeO2 and MnOx-CeO2 nanorods were much more active than the cubic nanorods. The physicochemical properties of the samples were characterized by TEM, XRD, BET, XPS, and H2-TPR techniques. The results revealed that the presence of oxygen vacancies in CeO2 and MnOx-CeO2 catalysts could increase the oxidizing ability of the catalysts surface. The addition of Mn could greatly improve the adsorption ability of CeO2 and more efficiently oxidize phenol and its intermediates. The synergy between Mn and Ce could further improve the catalyst redox properties and produce a larger amount of active oxygen species, which is the reason why MnOx-CeO2 nanorods are the most active catalysts among the catalysts investigated in this study.
Self-decarboxylation of trichloroacetic acid redox catalyzed by trichloroacetate ions in acetonitrile solutions
Valencia, Drochss P.,Astudillo, Pablo D.,Galano, Annia,Gonzalez, Felipe J.
, p. 318 - 325 (2013)
In mixtures of trichloroacetate ion and trichloroacetic acid in acetonitrile, trichloromethyl radicals are produced as a result of the redox reaction between the acid and its conjugate base. The reaction follows a loop mechanism in which the trichloroacet
Purification and characterization of a naringinase from Aspergillus aculeatus JMUdb058
Chen, Yuelong,Ni, Hui,Chen, Feng,Cai, Huinong,Li, Lijun,Su, Wenjin
, p. 931 - 938 (2013)
A naringinase from Aspergillus aculeatus JMUdb058 was purified, identified, and characterized. This naringinase had a molecular mass (MW) of 348 kDa and contained four subunits with MWs of 100, 95, 84, and 69 kDa. Mass spectrometric analysis revealed that the three larger subunits were β-d-glucosidases and that the smallest subunit was an α-l-rhamnosidase. The naringinase and its α-l-rhamnosidase and β-d-glucosidase subunits all had optimal activities at approximately pH 4 and 50 C, and they were stable between pH 3 and 6 and below 50 C. This naringinase was able to hydrolyze naringin, aesculin, and some other glycosides. The enzyme complex had a Km value of 0.11 mM and a kcat/Km ratio of 14 034 s-1 mM -1 for total naringinase. Its α-l-rhamnosidase and β-d-glucosidase subunits had Km values of 0.23 and 0.53 mM, respectively, and kcat/Km ratios of 14 146 and 7733 s -1 mM-1, respectively. These results provide in-depth insight into the structure of the naringinase complex and the hydrolyses of naringin and other glycosides.
Kinetics and mechanistic studies of Ru(III) catalyzed oxidation of p-hydroxy benzoic acid by sodium N-chloro-p-toluene sulphonamide in acidic media
Singh, Kamini,Singh
, p. 5121 - 5124 (2014)
Kinetics studies of the oxidation of p-hydroxy benzoic acid by sodium N-chloro-p-toluene sulphonamide (chloramine-T or CAT) have been carried out in aqueous perchloric acid medium at 35 °C. The reaction follows almost similar kinetics, being first order with respect to chloramine-T, p-hydroxy benzoic acid and Ru(III). The reaction exhibits inverse first order depedence on the concentration of medium [HClO4]. Variation of ionic strength by adding NaClO4have no significant effect on the reaction rate. The addition of p-toluene sulphonamide, which is one of the reaction products, had no significant effect on the reaction rate. Thermodynamic parameters were computed by studying the reactions at different temperature (303-318 K). The rate laws derived are in excellent agreement with the experimental results. A mechanism consistent with the above kinetic result has been suggested.
A highly selective photooxidation approach using O2 in water catalyzed by iron(II) bipyridine complex supported on NaY zeolite
Li, Jing,Ma, Wanhong,Huang, Yingping,Cheng, Mingming,Zhao, Jincai,Yu, Jimmy C.
, p. 2214 - 2215 (2003)
A new photocatalytic system involving iron(II) bipyridine supported on NaY zeolite (FeBY) shows excellent reactivity and selectivity in the oxidation of organic compounds. This approach allows highly controlled oxidation reaction to occur but avoids undesirable mineralization into CO2 and H 2O.
Photohydroxylation of 1,4-Benzoquinone in Aqueous Solution Revisited
Von Sonntag, Justus,Mvula, Eino,Hildenbrand, Knut,Von Sonntag, Clemens
, p. 440 - 451 (2004)
In water, photolysis of 1,4-benzoquinone, Q gives rise to equal amounts of 2-hydroxy-1,4-benzoquinone HOQ and hydroquinone QH2 which are formed with a quantum yield of ψ=0.42, independent of pH and Q concentration. By contrast, the rate of decay of the triplet (λmax=282 and ～ 410 nm) which is the precursor of these products increases nonlinearly (k= (2→3.8)×106 s-1) with increasing Q concentration ((0.2→10) mM). The free-radical yield detected by laser flash photolysis after the decay of the triplet also increases with increasing Q concentration but follows a different functional form. These observations are explained by a rapid equilibrium of a monomeric triplet Q* and an exciplex Q2* (K=5500±1000m-1). While Q* adds water and subsequent enolizes into 1,2,4-trihydroxybenzene Ph(OH) 3, Q2* decays by electron transfer and water addition yielding benzosemiquinone .QH and .OH adduct radicals .QOH. The latter enolizes to the 2-hydroxy-1,4-semiquinone radical .Q(OH)H within the time scale of the triplet decay and is subsequently rapidly (microsecond time scale) oxidized by Q to HOQ with the concomitant formation of .QH. On the post-millisecond time scale, that is, when .QH has decayed, Ph(OH)3 is oxidized by Q yielding HOQ and QH2 as followed by laser flash photolysis with diode array detection. The rate of this pH- and Q concentration-dependent reaction was independently determined by stopped-flow. This shows that there are two pathways to photohydroxylation; a free-radical pathway at high and a nonradical one at low Q concentration. In agreement with this, the yield of Ph(OH)3 is most pronounced at low Q concentration. In the presence of phosphate buffer, Q* reacts with H2PO4-giving rise to an adduct which is subsequently oxidized by Q to 2-phosphato-1,4-benzoquinone QP. The current view that .OH is an intermediate in the photohydroxylation of Q has been overturned. This view had been based on the observation of the .OH adduct of DMPO when Q is photolyzed in the presence of this spin trap. It is now shown that Q*/Q2* oxidizes DMPO (k ≈1×108M -1S-1) to its radical cation which subsequently reacts with water. Q*/Q2* react with alcohols by H abstraction (rates in units of M-1S-1): methanol (4.2×10 7), ethanol (6.7×107), 2-propanol (13×10 7) and tertiary butyl alcohol (～0.2×107). DMSO (2.7×109) and O2 (～2×109) act as physical quenchers.
High-pressure Kinetics of the Reaction of p-Benzoquinone with Di-n-butylamine in Some Aprotic Solvents
Sasaki, Muneo,Bando, Masaichi,Inagaki, Yoh-ichi,Amita, Fujitsugu,Osugi, Jiro
, p. 725 - 726 (1981)
The kinetics and the volume of activation of the title reaction to form 2-dibutylamino-p-benzoquinone in 1,2-dichloroethane and acetonitrile, -54 +/- 2 and -67 +/- 2 cm3/mol respectively, strongly support a reaction scheme in which ionic species are formed prior to the rate-determining step which is the second attack by the amine.
Cooperative structure direction of organosilanes and tetrapropylammonium hydroxide to generate hierarchical ZSM-5 zeolite with controlled porous structure
Shen, Yu,Han, Zongzhuang,Li, Hang,Li, Haichao,Wang, Gang,Wang, Fumin,Zhang, Xubin
, p. 6319 - 6327 (2018)
Hierarchical ZSM-5 zeolite with short-range ordered mesoporosity and hierarchical ZSM-5 zeolite nanorods were obtained via a direct hydrothermal synthesis by the cooperative structure direction of dimethyloctadecyl[3-(trimethoxysilyl)propyl]- ammonium chloride (TPOAC) and tetrapropylammonium hydroxide (TPAOH). Dimethyloctadecyl[3-(dimethoxymethylsilyl)propyl]ammonium chloride (DPOAC) and octadecyltrimethylammonium chloride (OTAC) were also employed as structure directing agents (SDA) to further explore the role of methoxysilyl groups in organosilanes during the formation of hierarchical structure. The prepared materials were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), N2 adsorption-desorption, FT-IR, UV-vis and inductively coupled plasma-optical emission spectroscopy (ICP-OES). The characterization results showed that the use of TPOAC and DPOAC would generate short-range ordered mesopores and irregular mesopores, respectively. Hierarchical ZSM-5 zeolite nanorods with worm-like intracrystalline mesopores could be obtained by adjusting the amount of silicon source. The lack of methoxysilyl groups in OTAC however could lead to phase separation problems. Furthermore, the hierarchical Fe-ZSM-5 zeolite with short-range ordered mesoporosity showed enhanced catalytic activity and stability for the hydroxylation of phenol at room temperature.
