527-17-3Relevant academic research and scientific papers
Potential for release of pulmonary toxic ketene from vaping pyrolysis of Vitamin E acetate
O'Shea, Donal F.,Wu, Dan
, p. 6349 - 6355 (2020)
A combined analytical, theoretical, and experimental study has shown that the vaping of vitamin E acetate has the potential to produce exceptionally toxic ketene gas, which may be a contributing factor to the upsurge in pulmonary injuries associated with using e-cigarette/ vaping products. Additionally, the pyrolysis of vitamin E acetate also produces carcinogen alkenes and benzene for which the negative long-term medical effects are well recognized. As temperatures reached in vaping devices can be equivalent to a laboratory pyrolysis apparatus, the potential for unexpected chemistries to take place on individual components within a vape mixture is high. Educational programs to inform of the danger are now required, as public perception has grown that vaping is not harmful.
Photoelectron Transfer between a Magnesium-Free-Base Porphyrin Heterodimer and Duroquinone. Selective Excitation and Time-Resolved EPR Studies
Levanon, Haim,Regev, Ayelet,Galili, Tamar,Hugerat, Muhamad,Chang, Chi K.,Fajer, Jack
, p. 13198 - 13205 (1993)
The photoexcited triplet state of a cofacial heterodimer, , comprised of Mg and H2 porphyrins, and photoinduced electron transfer (ET) between the heterodimer and duroquinone in 1:1 mixture of CH2Cl2/ethanol were studied by selective laser excitation combined with time-resolved CW or with pulsed EPR spectroscopies.ET originates from the photoexcited triplet or triplet radical pair states.Upon photoexcitation of the Mg subunit (580 nm), a noticeable delay time of ca.20 ns in ET is observed, whereas with photoexcitation of the H2 part (620 nm), no delay time in ET is noticed.The dependence of ET upon excitation wavelength is interpreted in terms of the formation and participation of a charge-transfer state that is operative at 205 K.The delay time is attributed to an intradimer ET that produces the triplet radical pair state 3.+-H2.->.Photoexcitation at 620 nm results in ET via the lower-lying triplet of H2 without involvement of the chargetransfer state.
Pentamethylphenyl (Ph*) and Related Derivatives as Useful Acyl Protecting Groups for Organic Synthesis: A Preliminary Study
Cheong, Choon Boon,Frost, James R.,Donohoe, Timothy J.
, p. 1828 - 1832 (2020/10/06)
A study of acyl protecting groups derived from the Ph? motif is reported. While initial studies indicated that a variety of functional groups were not compatible with the Br 2-mediated cleavage conditions required to release the Ph? group, strategies involving the use of different reagents or a modification of Ph? itself (Ph*OH) were investigated to solve this problem.
Photocatalytic Hydrogen Evolution from Plastoquinol Analogues as a Potential Functional Model of Photosystem I
Fukuzumi, Shunichi,Hong, Young Hyun,Lee, Yong-Min,Nam, Wonwoo
, p. 14838 - 14846 (2020/11/03)
The recent development of a functional model of photosystem II (PSII) has paved a new way to connect the PSII model with a functional model of photosystem I (PSI). However, PSI functional models have yet to be reported. We report herein the first potential functional model of PSI, in which plastoquinol (PQH2) analogues were oxidized to plastoquinone (PQ) analogues, accompanied by hydrogen (H2) evolution. Photoirradiation of a deaerated acetonitrile (MeCN) solution containing hydroquinone derivatives (X-QH2) as a hydrogen source, 9-mesityl-10-methylacridinium ion (Acr+-Mes) as a photoredox catalyst, and a cobalt(III) complex, CoIII(dmgH)2pyCl (dmgH = dimethylglyoximate monoanion; py = pyridine) as a redox catalyst resulted in the evolution of H2 and formation of the corresponding p-benzoquinone derivatives (X-Q) quantitatively. The maximum quantum yield for photocatalytic H2 evolution from tetrachlorohydroquinone (Cl4QH2) with Acr+-Mes and CoIII(dmgH)2pyCl and H2O in deaerated MeCN was determined to be 10%. Photocatalytic H2 evolution is started by electron transfer (ET) from Cl4QH2 to the triplet ET state of Acr+-Mes to produce Cl4QH2?+ and Acr?-Mes with a rate constant of 7.2 × 107 M-1 s-1, followed by ET from Acr?-Mes to CoIII(dmgH)2pyCl to produce [CoII(dmgH)2pyCl]-, accompanied by the regeneration of Acr+-Mes. On the other hand, Cl4QH2?+ is deprotonated to produce Cl4QH?, which transfers either a hydrogen-atom transfer or a proton-coupled electron transfer to [CoII(dmgH)2pyCl]- to produce a cobalt(III) hydride complex, [CoIII(H)(dmgH)2pyCl]-, which reacts with H+ to evolve H2, accompanied by the regeneration of CoIII(dmgH)2pyCl. The formation of [CoII(dmgH)2pyCl]- was detected by electron paramagnetic resonance measurements.
Synthesis and characterization of a novel ruthenium(ii) trisbipyridine complex magnetic nanocomposite for the selective oxidation of phenols
Fei, Zhengxin,Chen, Feng,Zhong, Mingqiang,Qiu, Jianping,Li, Weidong,Sadeghzadeh, Seyed Mohsen
, p. 28078 - 28088 (2019/09/30)
Anchoring ruthenium(ii) trisbipyridine complex [Ru(Bpy)3]2+ into a magnetic dendritic fibrous silica nanostructure produces an unprecedented strong nanocatalyst, FeNi3/DFNS/[Ru(Bpy)3]2+. Impressive oxidation of phenols to 1,4-benzoquinones catalyzed by FeNi3/DFNS/[Ru(Bpy)3]2+ is obtained in acetonitrile and water solution with molecular dioxygen as oxidant. Exclusively, apparently inert phenols such as phenol itself and mono-alkyl-substituted phenols are impressively oxidized to produce 1,4-benzoquinones through activation of the C-H bond in the position para to the carbon-oxygen bond under mild conditions. In addition, the production of industrially significant quinones that are known intermediates for vitamin combinations is investigated and studied FeNi3/DFNS/[Ru(Bpy)3]2+ magnetic nanoparticles were produced, and their properties were investigated by AFM, FTIR, XRD, TGA, SEM, TEM, and VSM.
Selective activation of C–H bond into C[dbnd]O bond of phenols in para-position via aerobic oxidation
Yang, Shilei,Xu, Guoqiang,Shi, Song,Xin, Hongchuan,Gao, Jin,An, Zengjian
, p. 105 - 108 (2019/02/25)
An efficient method for the oxidation of phenols to 1,4-benzoquinones catalyzed by cuprous(I) chloride was achieved in a solution of acetonitrile and water using molecular dioxygen as an oxidant. Particularly, the inert phenols, such as phenol and mono-alkyl substituted phenols, were effectively oxidized to 1,4-benzoquinones via the selective activation of C–H bond in para-position into C[dbnd]O bond under mild conditions. The catalyst shows high activity for unsubstituted or alkyl substituted phenols, but no effect on substituted phenols with electron-withdrawing groups. This study offers an aerobic method for the selective oxidation of aromatic phenols to 1,4-benzoquinones.
Bismuth-catalyzed methylation and alkylation of quinone derivatives with tert-butyl peroxybenzoate as an oxidant
Yang, Jian,Dong, Yu,He, Shuai,Shi, Zhi-Chuan,Wang, Yu,Wang, Ji-Yu
, (2019/11/26)
A bismuth-catalyzed methylation of quinones in the presence of tert-butyl peroxybenzoate (TBPB) was developed via a radical reaction mechanism. Particularly, TBPB was used not only as an efficient oxidant, but also as a green methyl source in such transformation. Moreover, this method could also be efficiently extended to the alkylation of quinones. This reaction tolerated a series of functional groups and prepared a series of derivatives of vitamin K3 and benzoquinone. Notably, antimalarial parvaquone was synthesized by the reaction.
Selective iron-catalyzed oxidation of phenols and arenes with hydrogen peroxide: Synthesis of vitamin e intermediates and vitamin k3
Moeller, Konstanze,Wienhoefer, Gerrit,Schroeder, Kristin,Join, Benoit,Junge, Kathrin,Beller, Matthias
experimental part, p. 10300 - 10303 (2010/10/21)
(Figure Presented). Pumping iron! Convenient iron-based catalyst systems for the selective oxidation of arenes and phenols with hydrogen peroxide to give 1, 4-quinones have been developed. This selective oxidation reaction takes place under mild conditions (room temperature, alcoholic solvents) with H 2O2 as the terminal oxidant.
Polymer incarcerated gold catalyzed aerobic oxidation of hydroquinones and their derivatives
Miyamura, Hiroyuki,Shiramizu, Mika,Matsubara, Ryosuke,Kobayashi, Shu
, p. 360 - 361 (2008/09/20)
Polymer-incarcerated gold (PI Au) cluster catalysts mediated aerobic oxidation of hydroquinones and catechols to quinones very efficiently under mild conditions. The characteristic role of water in the reaction system was also observed. Copyright
Aerobic oxidation of hydroquinone derivatives catalyzed by polymer-incarcerated platinum catalyst
Miyamura, Hiroyuki,Shiramizu, Mika,Matsubara, Ryosuke,Kobayashi, Shu
supporting information; experimental part, p. 8093 - 8095 (2009/04/13)
(Chemical Equation Presented) It's a lock-in! A remarkably wide substrate scope of hydroquinones are oxidized to quinones in high yields in a platinum-catalyzed process with as low as 0.05 mol% catalyst. The aerobic oxidation is catalyzed by platinum nanoclusters trapped in a styrene-based polymer network (see scheme, PI Pt=polymer-incarcerated nanoclusters). The catalyst could be reused at least 13 times without any loss of catalytic activity.
