589-92-4Relevant articles and documents
Studies Concerning the Factors Affecting the Formation of Cyclohexanone Intermediates in the Catalytic Hydrogenation of Phenols. I. Hydrogenation of p-Cresol over Various Pd-C Catalysts
Higashijima, Michio,Nishimura, Shigeo
, p. 824 - 830 (1992)
The catalytic hydrogenation of p-cresol with commercial Pd on active carbon (Pd-C), water-washed Pd-C (Pd-C-N), acid-treated Pd-C (Pd-C-A), and base-treated Pd-C (Pd-C-B) has been kinetically studied in cyclohexane as a solvent under 0.15-8.0 MPa hydrogen pressure at 80 deg C.Under each reaction condition, the hydrogenation rate constants for the cresol and the ketone intermediate, k1+k3 and k2, respectively, the relative reactivity of the ketone to the cresol (K) and the ratio of the adsorption coefficient of the ketone to that of the cresol (b2/b1) were determined of the basis of a Langmuir-Hinshelwood model.Regardless of the difference in the nature of the catalysts, hydrogenations with these catalysts always gave high selectivities of 0.85-1.0 for the formation of the ketone intermediate, and small values of 0.014-0.62 for the relative reactivity (K).The small values of K over Pd-C and Pd-C-B were shown to be mostly due to the small values of k2/(k1+k3).In contrast, even smaller values of K over Pd-C-N and Pd-C-A were found due to a great difference in the strength of adsorption between the cresol and the ketone intermediate.In general, both the values of K and k2/(k1+k3) increase with increasing hydrogen pressure.All of the experimental results show that both the alkaline impurities associated with catalyst preparation and the hydrogen pressure are the most important factors affecting the formation of the ketone intermediate.
(±)-Camphor sulfonic acid assisted IBX based oxidation of 1° and 2° alcohols
Kumar, Kamlesh,Joshi, Penny,Rawat, Diwan S
, (2021/09/02)
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Visible-light photocatalytic selective oxidation of C(sp3)-H bonds by anion-cation dual-metal-site nanoscale localized carbon nitride
Duan, Limei,Li, Peihe,Li, Wanfei,Liu, Jinghai,Liu, Ying,Liu, Zhifei,Lu, Ye,Sarina, Sarina,Wang, Jinghui,Wang, Yin,Wang, Yingying,Zhu, Huaiyong
, p. 4429 - 4438 (2021/07/12)
Selective oxidation of C(sp3)-H bonds to carbonyl groups by abstracting H with a photoinduced highly active oxygen radical is an effective method used to give high value products. Here, we report a heterogeneous photocatalytic alkanes C-H bonds oxidation method under the irradiation of visible light (λ= 425 nm) at ambient temperature using an anion-cation dual-metal-site modulated carbon nitride. The optimized cation (C) of Fe3+or Ni2+, with an anion (A) of phosphotungstate (PW123?) constitutes the nanoscale dual-metal-site (DMS). With a Fe-PW12dual-metal-site as a model (FePW), we demonstrate a A-C DMS nanoscale localized carbon nitride (A-C/g-C3N4) exhibiting a highly enhanced photocatalytic activity with a high product yield (86% conversion), selectivity (up to 99%), and a wide functional group tolerance (52 examples). The carbon nitride performs the roles of both the visible light response, and improves the selectivity for the oxidation of C(sp3)-H bonds to carbonyl groups, along with the function of A-C DMS in promoting product yield. Mechanistic studies indicate that this reaction follows a radical pathway catalyzed by a photogenerated electron and hole on A-C/g-C3N4that is mediated by thetBuO˙ andtBuOO˙ radicals. Notably, a 10 g scale reaction was successfully achieved for alkane photocatalytic oxidation to the corresponding product with a good yield (80% conversion), and high selectivity (95%) under natural sunlight at ambient temperature. In addition, this A-C/g-C3N4photocatalyst is highly robust and can be reused at least six times and the activity is maintained.