6485-57-0Relevant academic research and scientific papers
Activation of Molecular Oxygen Using Durable Cobalt Encapsulated with Nitrogen-Doped Graphitic Carbon Shells for Aerobic Oxidation of Lignin-Derived Alcohols
Sun, Yuxia,Ma, Hong,Luo, Yang,Zhang, Shujing,Gao, Jin,Xu, Jie
, p. 4653 - 4661 (2018)
It has long been a challenge for activating O2 by transition-metal nanocatalysts, which might lose activity due to strong tendency for oxidation. Herein, O2 could be activated by durable encapsulated cobalt nanoparticles (NPs) with N-doped graphitic carbon shells (Co@N-C), but not by encapsulated cobalt NPs with graphitic carbon, exposed cobalt NPs supported on activated carbon, or N-doped carbon. Electron paramagnetic resonance, real-time in situ FTIR spectroscopy, and mass spectrometry measurements demonstrated the generation of the highly active superoxide radical, O2.?. This unique ability enables Co@N-C to afford an excellent catalytic performance in model aerobic oxidation of monomeric lignin-derived alcohols. Further analysis elucidated that encapsulated cobalt and nitrogen-doped graphitic carbon might contribute to the capacity through influencing the electronic properties of outer layers. Moreover, through isolation by N-doped graphitic carbon shells, the inner metallic cobalt NPs are inaccessible in term of either alcohols or oxygenated products, and a distinctive resistance to leaching and agglomeration has been achieved.
Radical-scavenging activity of butylated hydroxytoluene (BHT) and its metabolites
Fujisawa, Seiichiro,Kadoma, Yoshinori,Yokoe, Ichiro
, p. 189 - 195 (2004)
To clarify the radical-scavenging activity of butylated hydroxytoluene (BHT), a food additive, stoichiometric factors (n) and inhibition rate constants (kinh) were determined for 2,6-di-tert-butyl-4-methylphenol (BHT) and its metabolites 2,6-di-tert-butyl-p-benzoquinone (BHT-Q), 3,5-di-tert-butyl-4-hydroxybenzaldehyde (BHA-CHO) and 3,5-di-tert-butyl-4- hydroperoxy-4-methyl-2,5-cyclohexadiene-1-one (BHT-OOH). Values of n and k inh were determined from differential scanning calorimetry (DSC) monitoring of the polymerization of methyl methacrylate (MMA) initiated by 2,2′-azobis(isobutyronitrile) (AIBN) or benzoyl peroxide (BPO) at 70°C in the presence or absence of antioxidants (BHT-related compounds). The n values declined in the order BHT (1-2) > BHT-CHO, BHT-OOH (0.1-0.3) > BHT-Q (～0). The n value for BHT with AIBN was approximately 1.0, suggesting dimerization of BHT. The kinh values declined in the order BHT-Q ((3.5-4.6)×104 M-1 s-1) > BHT-OOH (0.7-1.9×104 M-1 s-1) > BHT-CHO ((0.4-1.7)×104 M-1 s-1) > BHT ((0.1-0.2)×104 M-1 s-1). The k inh for metabolites was greater than that for the parent BHT. Growing MMA radicals initiated by BPO were suppressed much more efficiently by BHT or BHT-Q compared with those initiated by AIBN. BHT was effective as a chain-breaking antioxidant.
Visible-Light-Mediated Aerobic Oxidative C(sp3)?C(sp3) Bond Cleavage of Morpholine Derivatives Using 4CzIPN as a Photocatalyst
Dong, Chun-Lin,Huang, Lan-Qian,Guan, Zhi,Huang, Chu-Sheng,He, Yan-Hong
supporting information, p. 3803 - 3811 (2021/06/28)
Herein, a metal-free strategy for the aerobic oxidative cleavage of the inert C(sp3)?C(sp3) bond was developed. Deconstruction of morpholine derivatives was conducted using visible light as an energy source and O2 as an oxidant under mild conditions. This procedure demonstrated suitable selectivity and functional group tolerance. Moreover, a possible mechanism involving a radical process was proposed based on a series of mechanism exploration and control experiments. (Figure presented.).
Organophotocatalytic Aerobic Oxygenation of Phenols in a Visible-Light Continuous-Flow Photoreactor
Wellauer, Jo?l,Miladinov, Dragan,Buchholz, Thomas,Schütz, Jan,Stemmler, René T.,Medlock, Jonathan A.,Bonrath, Werner,Sparr, Christof
supporting information, p. 9748 - 9752 (2021/05/27)
A mild photocatalytic phenol oxygenation enabled by a continuous-flow photoreactor using visible light and pressurized air is described herein. Products for wide-ranging applications, including the synthesis of vitamins, were obtained in high yields by precisely controlling principal process parameters. The reactor design permits low organophotocatalyst loadings to generate singlet oxygen. It is anticipated that the efficient aerobic phenol oxygenation to benzoquinones and p-quinols contributes to sustainable synthesis.
Visible-Light-Mediated Additive-Free Decarboxylative Ketonization Reaction of Acrylic Acids: An Access to α-Thiocyanate Ketones
Wang, Zhi-Lv,Chen, Jie,He, Yan-Hong,Guan, Zhi
supporting information, p. 3741 - 3749 (2021/03/09)
Visible-light-mediated additive-free decarboxylative functionalization of acrylic acids has been developed. The reaction uses inexpensive organic dye 9,10-dicyanoanthracene as a photocatalyst and uses the ubiquitous dioxygen as both an oxygen source and an oxidant. Through this mild and environmentally friendly method, a series of important α-thiocyanate ketones can be generated from easily available acrylic acids and ammonium thiocyanate. In addition, the facile transformation of product α-thiocyanate ketones makes this method have great potential for application in organic and pharmaceutical chemistry.
Visible light-mediated, rose Bengal-catalyzed oxidative radical C[sbnd]H cyclization of alkyl 1,1′-biaryl-2-ones: An efficient synthesis of 10-alkylphenanthren-9-ols in water
Natarajan, Palani,Kumar, Naveen,Chaudhary, Renu,Venugopalan, Paloth
supporting information, (2020/03/23)
A visible light-mediated (blue LED: λ = 455 ± 10 nm), rose bengal-catalyzed intramolecular cycloaromatization reaction of alkyl 1, 1′-biaryl-2-ones for the synthesis of 10-alkylphenanthren-9-ols in water under open air atmosphere at ambient conditions has been developed. Experimental studies demonstrate that the reaction proceeded via a radical pathway. This protocol is applicable to a wide variety of substrates giving expected 10-alkylphenanthren-9-ols in good yields, appropriate for the gram-scale synthesis, atom economy, and eco-friendly as compared to literature reported methodology for the preparation of phenanthrol derivatives. Moreover, to the best of our knowledge, no instance has hitherto been accounted on the visible light-induced transformation of readily available alkyl 1,1′-biaryl-2-ones to 10-alkylphenanthren-9-ols.
Photo-Mediated Decarboxylative Ketonization of Atropic Acids with Sulfonyl Hydrazides: Direct Access to β-Ketosulfones
Chen, Jie,Allyson, Zoe G.,Xin, Jing-Rui,Guan, Zhi,He, Yan-Hong
supporting information, p. 2045 - 2051 (2020/02/11)
An efficient formation of synthetically and biologically relevant β-ketosulfones via a photo-mediated decarboxylative ketonization of atropic acids was disclosed. The approach features metal-free conditions, good functional group compatibility, readily available starting materials and the use of ubiquitous dioxygen as both oxygen source and oxidant. Furthermore, mechanistic studies reveal that the decarboxylative ketonization reaction proceeds via a radical mechanism and may involve a radical chain reaction. (Figure presented.).
Synthesis of Benzothiazoles via Photooxidative Decarboxylation of α-Keto Acids
Monga, Aparna,Bagchi, Sourav,Soni, Raj Kumar,Sharma, Anuj
, p. 2232 - 2237 (2020/03/04)
Herein, synthesis of benzothiazoles via decarboxylative cross-coupling between α-keto acids and 2-aminothiophenols under blue LED irradiation without using any photocatalyst or metal at room temperature is described. The formation of benzothiazole is driven by the EDA (electron donor-acceptor) complex formed between α-keto acid and 2-aminothiophenol. This methodology gives easy access to 2-substituted and -unsubstituted benzothiazoles in moderate to good yields. α-Keto acids and 2-aminothiophenols bearing different functional groups were easily transformed under the given conditions. (Figure presented.).
Visible-Light-Mediated Rose Bengal-Catalyzed α-Hydroxymethylation of Ketones with Methanol
Yang, Jingya,Xie, Dongtai,Zhou, Hongyan,Chen, Shuwen,Duan, Jiaokui,Huo, Congde,Li, Zheng
supporting information, p. 3471 - 3476 (2018/09/12)
A visible-light-mediated α-hydroxymethylation of ketones using methanol as the hydroxymethylating reagent has been developed. Using 1 mol% rose bengal as the photosensitizer and air as the green oxidant, the reactions proceeded smoothly at room temperature. Experimental studies indicate the reaction proceeded via a radical pathway. (Figure presented.).
BODIPY catalyzed amide synthesis promoted by BHT and air under visible light
Wang, Xiao-Fei,Yu, Shu-Sheng,Wang, Chao,Xue, Dong,Xiao, Jianliang
, p. 7028 - 7037 (2016/07/30)
A novel and efficient protocol for the synthesis of amides is reported which employs a BODIPY catalyzed oxidative amidation reaction between aromatic aldehydes and amines under visible light. Compared with the known Ru or Ir molecular catalysts and other organic dyes, the BODIPY catalyst showed higher reactivity toward this reaction. Mechanistic studies reveal that dioxygen could be activated through an ET and a SET pathway, forming active peroxides in situ, which are vital for the key step of the reaction, i.e. the oxidation of hemiaminal to amide. The broad substrate scope and mild reaction conditions make this reaction practically useful and environmentally friendly for the synthesis of amide compounds.
