576-24-9Relevant articles and documents
Investigation of the photocatalytic activity of TiO2-polyoxometalate systems
Ozer, Ruya R.,Ferry, John L.
, p. 3242 - 3246 (2001)
The present study reports the investigation of polyoxometalate catalyzed electron transfer from the conduction band of photoexcited TiO2 to molecular oxygen. The oxidation of 1,2-dichlorobenzene (DCB) was used as an index reaction for evaluating the photocatalyst systems TiO2-PW12O403-, TiO2-SiW12O40,4- and TiO2-W10O324- in oxygenated aqueous solution. Addition of these polyoxometalate (POM) anions to TiO2 suspensions resulted in significant rate enhancement for DCB oxidation. Photodegradation kinetics exhibited [POM] dependence, experiencing different maximum (k = 0.0318 min-1, 0.0108 min-1, and 0.0066 min-1) for each POM at different [POM] (0.1 mM PW12O403-, 0.07 mM SiW12O40,4- and 1 mM W10O32,4- respectively). The probability that the difference in the adsorption affinity of POMs on TiO2 surface could account for the observed ranking of photodegradation rates was ruled out by adsorption isotherm experiments that revealed similar binding constants for each POM (467 M-1, 459 M-1, and 417 M-1 for PW12O403-, SiW12O404-, and W10O324-, respectively). DCB degradation over TiO2 with O2 or POM+O2 systems can be modeled by the Langmuir-Hinshelwood (saturation kinetics) model. The concentration-independent rate constants (kL-H) for TiO2-O2, TiO2-W10O324-, TiO2-SiW12O404-, and TiO2-PW12O403- were 0.0818, 0.152, 0.421, and 0.638 min-1, respectively. An analysis of ΔG for electron transfer from the conduction band of TiO2 to POMs in this study shows that the electron transfer takes place even when it is endothermic.
Ammonium Salt-Catalyzed Highly Practical Ortho-Selective Monohalogenation and Phenylselenation of Phenols: Scope and Applications
Xiong, Xiaodong,Yeung, Ying-Yeung
, p. 4033 - 4043 (2018/05/22)
An ortho-selective ammonium chloride salt-catalyzed direct C-H monohalogenation of phenols and 1,1′-bi-2-naphthol (BINOL) with 1,3-dichloro-5,5-dimethylhydantoin (DCDMH) as the chlorinating agent has been developed. The catalyst loading was low (down to 0.01 mol %) and the reaction conditions were very mild. A wide range of substrates including BINOLs were compatible with this catalytic protocol. Chlorinated BINOLs are useful synthons for the synthesis of a wide range of unsymmetrical 3-aryl BINOLs that are not easily accessible. In addition, the same catalytic system can facilitate the ortho-selective selenylation of phenols.
N-Substituted 3(10H)-Acridones as Visible-Light, Water-Soluble Photocatalysts: Aerobic Oxidative Hydroxylation of Arylboronic Acids
Xie, Hong-Yan,Han, Li-Shuai,Huang, Shan,Lei, Xiantao,Cheng, Yong,Zhao, Wenfeng,Sun, Hongbin,Wen, Xiaoan,Xu, Qing-Long
, p. 5236 - 5241 (2017/05/24)
We disclosed a novel water-soluble photocatalyst that could promote aerobic oxidative hydroxylation of arylboronic acids to furnish phenols in excellent yields. This transformation uses visible-light irradiation under environmentally friendly conditions, that is, water-soluble catalyst, metal-free, green oxidant, room temperature.
Energy-efficient green catalysis: Supported gold nanoparticle-catalyzed aminolysis of esters with inert tertiary amines by C-O and C-N bond activations
Bao, Yong-Sheng,Baiyin, Menghe,Agula, Bao,Jia, Meilin,Zhaorigetu, Bao
supporting information, p. 6715 - 6719 (2014/08/05)
Catalyzed by supported gold nanoparticles, an aminolysis reaction between various aryl esters and inert tertiary amines by C-O and C-N bond activations has been developed for the selective synthesis of tertiary amides. Comparison studies indicated that the gold nanoparticles could perform energy-efficient green catalysis at room temperature, whereas Pd(OAc)2 could not.
