99-08-1Relevant articles and documents
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Roberts et al.
, p. 4285 (1958)
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Photoinduced Iron-Catalyzed ipso-Nitration of Aryl Halides via Single-Electron Transfer
Wu, Cunluo,Bian, Qilong,Ding, Tao,Tang, Mingming,Zhang, Wenkai,Xu, Yuanqing,Liu, Baoying,Xu, Hao,Li, Hai-Bei,Fu, Hua
, p. 9561 - 9568 (2021/08/06)
A photoinduced iron-catalyzed ipso-nitration of aryl halides with KNO2 has been developed, in which aryl iodides, bromides, and some of aryl chlorides are feasible. The mechanism investigations show that the in situ formed iron complex by FeSO4, KNO2, and 1,10-phenanthroline acts as the light-harvesting photocatalyst with a longer lifetime of the excited state, and the reaction undergoes a photoinduced single-electron transfer (SET) process. This work represents an example for the photoinduced iron-catalyzed Ullmann-type couplings.
Niobium oxide prepared through a novel supercritical-CO2-assisted method as a highly active heterogeneous catalyst for the synthesis of azoxybenzene from aniline
Tao, Yehan,Singh, Bhawan,Jindal, Vanshika,Tang, Zhenchen,Pescarmona, Paolo P.
, p. 5852 - 5864 (2019/11/11)
High-surface area Nb2O5 nanoparticles were synthesised by a novel supercritical-CO2-assisted method (Nb2O5-scCO2) and were applied for the first time as a heterogeneous catalyst in the oxidative coupling of aniline to azoxybenzene using the environmentally friendly H2O2 as the oxidant. The application of scCO2 in the synthesis of Nb2O5-scCO2 catalyst resulted in a significantly enhanced catalytic activity compared to a reference catalyst prepared without scCO2 (Nb2O5-Ref) or to commercial Nb2O5. Importantly, the Nb2O5-scCO2 catalyst achieved an aniline conversion of 86% (stoichiometric maximum of 93% with the employed aniline-to-H2O2 ratio of 1?:?1.4) with an azoxybenzene selectivity of 92% and with 95% efficiency in H2O2 utilisation in 45 min without requiring external heating (the reaction is exothermic) and with an extremely low catalyst loading (weight ratio between the catalyst and substrate, Rc/s = 0.005). This performance largely surpasses that of any other heterogeneous catalyst previously reported for this reaction. Additionally, the Nb2O5 catalyst displayed high activity also for substituted anilines (e.g. methyl or ethyl-anilines and para-anisidine) and was reused in consecutive runs without any loss of activity. Characterisation by means of N2-physisorption, XRD, FTIR and TEM allowed the correlation of the remarkable catalytic performance of Nb2O5-scCO2 to its higher surface area and discrete nanoparticle morphology compared to the aggregated larger particles constituting the material prepared without scCO2. A catalytic test in the presence of a radical scavenger proved that the reaction follows a radical pathway.
Pd-poly(N-vinyl-2-pyrrolidone)/MCM-48 nanocomposite: a novel catalyst for the Ullmann reaction
Mosaddegh, Neda,Yavari, Issa
, p. 2013 - 2021 (2018/07/29)
Abstract: Homocoupling of aryl halides (Ullmann-type reaction) promoted by a Pd-poly(N-vinyl-2-pyrrolidone)/MCM-48 (Pd–PVP/MCM-48) nanocomposite catalyst is described. In situ polymerization method was employed to prepare composite poly(N-vinyl-2-pyrrolidone)/MCM-48 (PVP/MCM-48) which was used as a support for palladium nanoparticles obtained by reducing Pd(OAc)2 with hydrazine hydrate. FT-IR, XPS, XRD, UV–Vis, SEM, and BET techniques were used to study the chemical and physical properties of the catalyst. The catalytic performance of this heterogeneous catalyst was specified for Ullmann-type reaction between aryl halies in DMF. The catalyst was good with regard to its stability and it can be reused up to six times without significant loss of its activity.