scholarly journals Partial oxidation of alkanes by dioxiranes formed in situ at low temperature

Author(s):  
Sara Yacob ◽  
Michael J. Caulfield ◽  
Timothy A. Barckholtz

Partial oxidation catalysts capable of efficiently operating at low temperatures may limit the over-oxidation of alkane substrates and thereby improve selectivity. This work focuses on examining alkane oxidation using completely metal-free organocatalysts, dioxiranes. The dioxiranes employed here are synthesized by oxidation of a ketone using a terminal oxidant, such as hydrogen peroxide. Our work generates the dioxirane in situ , so that the process can be catalytic with respect to the ketone. To date, we have demonstrated selective partial oxidation of adamantane using ketone catalysts resulting in yields upwards of 60% towards 1-adamantanol with greater than 99% selectivity. Furthermore, we have demonstrated that changing the electrophilic character of the ketone R groups to contain more electron-donating ligands facilitates the dioxirane ring formation and improves overall oxidation yields. Isotopic labelling studies using H 2 18 O 2 show the preferential incorporation of an 18 O label into the parent ketone, providing evidence for a dioxirane intermediate formed in situ . The isotopic labelling studies, along with solvent effect studies, suggest the formation of peracetic acid as a reactive intermediate. This article is part of a discussion meeting issue ‘Providing sustainable catalytic solutions for a rapidly changing world’.

2019 ◽  
Vol 252 ◽  
pp. 128-137 ◽  
Author(s):  
André Torres-Pinto ◽  
Maria J. Sampaio ◽  
Cláudia G. Silva ◽  
Joaquim L. Faria ◽  
Adrián M.T. Silva

2019 ◽  
Vol 326 ◽  
pp. 134967
Author(s):  
Jing Zhang ◽  
Ming Zhao ◽  
Jun Yang ◽  
Gang Wu ◽  
Huaping Wu ◽  
...  

Carbon ◽  
2015 ◽  
Vol 95 ◽  
pp. 949-963 ◽  
Author(s):  
Valentina Perazzolo ◽  
Christian Durante ◽  
Roberto Pilot ◽  
Andrea Paduano ◽  
Jian Zheng ◽  
...  

Author(s):  
F. H. Louchet ◽  
L. P. Kubin

Experiments have been carried out on the 3 MeV electron microscope in Toulouse. The low temperature straining holder has been previously described Images given by an image intensifier are recorded on magnetic tape.The microtensile niobium samples are cut in a plane with the two operative slip directions [111] and lying in the foil plane. The tensile axis is near [011].Our results concern:- The transition temperature of niobium near 220 K: at this temperature and below an increasing difference appears between the mobilities of the screw and edge portions of dislocations loops. Source operation and interactions between screw dislocations of different slip system have been recorded.


2002 ◽  
Vol 725 ◽  
Author(s):  
S.B. Phelan ◽  
B.S. O'Connell ◽  
G. Farrell ◽  
G. Chambers ◽  
H.J. Byrne

AbstractThe current voltage characteristics of C60 thin film sandwich structures fabricated by vacuum deposition on indium tin oxide (ITO) with an aluminium top electrode are presented and discussed. A strongly non-linear behavior and a sharp increase in the device conductivity was observed at relatively low voltages (∼2V), at both room and low temperatures (20K). At room temperature the system is seen to collapse, and in situ Raman measurements indicate a solid state reduction of the fullerene thin film to form a polymeric state. The high conductivity state was seen to be stable at elevated voltages and low temperatures. This state is seen to be reversible with the application of high voltages. At these high voltages the C60 film was seen to sporadically emit white light at randomly localized points analogous to the much documented Electroluminescence in single crystals.


1994 ◽  
Vol 30 (3) ◽  
pp. 73-78 ◽  
Author(s):  
O. Tünay ◽  
S. Erden ◽  
D. Orhon ◽  
I. Kabdasli

This study evaluates the characterization and treatability of 2,4-D production wastewaters. Wastewaters contain 20000-40000 mg/l COD, 17000-30000 mg/l chloride and pH is around 1.0. Chemical oxidation with hydrogen peroxide provided almost complete COD removal. The optimum conditions are 3:1 H2O2/COD oxidant dosage, 3000 mg/l Fe3+ as catalyst and pH 3. Partial oxidation at 0.5:1 H2O2//COD ratio is also effective providing 67% COD removal. A batch activated sludge system is used for biological treatability. Dilution is needed to maintain a tolerable chloride concentration which increases through COD removal. pH also increased during COD removal. 85% COD removal is obtained for the 50% dilution at an organic loading of 0.3 day‒1 on a COD basis. Completely and partially oxidized wastewaters are also treated in the activated sludge down to 30 mg/l BOD5.


2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Qingyao Wu ◽  
Jingjing Cao ◽  
Xiao Wang ◽  
Yan Liu ◽  
Yajie Zhao ◽  
...  

A Correction to this paper has been published: https://doi.org/10.1038/s41467-021-21490-z


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