2168-93-6Relevant academic research and scientific papers
Polymer-supported Oxobis(pentane-2,4-dionato)vanadium(IV) Catalyst for Reactions involving t-Butyl Hydroperoxide
Bhaduri, Sumit,Ghosh, Annoottam,Khwaja, Hanif
, p. 447 - 451 (1981)
The polymer-supported title compound catalyses the homolytic decomposition of ButO2H and its reactions with Me2SO, Bun2S, and cyclohexene to give Me2SO2, Bun2SO, and cyclohexene oxide respectively.Polymer-chain participation in the radical reactions seems to give additional catalytic pathways for the decomposition of ButO2H.Recycling of the polymer-supported complex in the conversion of Me2SO into Me2SO2 results in lower product yields due to the loss of metal ions.Comparative studies between the polymer-supported and the homogeneous systems suggest extra stability for the polymer-anchored, catalytically active species.The diffusion barrier between the reactants in solution and the polymer influences the rates and may be responsible for this extra stability.
Switching the activity of a photoredox catalyst through reversible encapsulation and release
Bianchini, Giulio,Scarso, Alessandro,Sorella, Giorgio La,Strukul, Giorgio
, p. 12082 - 12084 (2012)
Reversible encapsulation of [Ru(bpy)3]2+ within a self-assembled hexameric resorcin[4]arene capsule turns off the photocatalytic aerobic oxidation of an aliphatic sulfide. Upon addition of a competitive cationic guest, the Ru(ii) catalyst is released into solution where its catalytic activity is restored.
Nb and Zr modified MWW zeolites-characterisation and catalytic activity
Wojtaszek-Gurdak, Anna,Ziolek, Maria
, p. 22326 - 22333 (2015)
Hydrogen forms of MCM-22 and delaminated MCM-56 zeolites were modified with niobium and zirconium species. The structure/texture and surface properties, as well as the catalytic activity for dibutyl sulfide oxidation, of the two types of modified zeolites were compared. The presence of Br?nsted (BAS) and Lewis (LAS) acid sites was detected after pyridine adsorption in all the prepared materials. The highest number of BAS and LAS was observed for HMCM-22. The number of BAS significantly decreased after metal modification because of the interaction between the metal sources and the BAS. External silanol groups of zeolites also participate in metal anchoring. The catalysts obtained were tested for liquid phase dibutyl sulfide oxidation with hydrogen peroxide. The texture of the zeolites and the nature of the metal modifier have a crucial effect on the oxidation of dibutyl sulfide. MCM-56 zeolites are more active than their counterparts of MCM-22 type. Application of niobium containing zeolites significantly increases the reaction rate, leading to 95% conversion after 3 h. The remarkable role of the Nb species is due to its interaction with H2O2 towards peroxo/superoxo species. Modification of both zeolites with zirconium does not increase their activity because of the strong interaction of zirconium species with sulfur compounds. This journal is
Reactions in clay media: Photooxidation of sulfides by clay-bound methylene blue
Madhavan,Pitchumani
, p. 8391 - 8394 (2001)
Photooxidation of dialkyl and alkyl aryl sulfides to the corresponding sulfoxides with clay-bound methylene blue is studied in acetonitrile. A significant increase in sulfoxide/sulfone ratio and a marginal increase in cooxidation of a second sulfide molecule are observed. The results are explained in terms of a suitable mechanism involving persulfoxide and thiadioxirane intermediates.
Electron Transfer and Singlet Oxygen Mechanisms in the Photooxygenation of Dibutyl Sulfide and Thioanisole in MeCN Sensitized by N-Methylquinolinium Tetrafluoborate and 9,10-Dicyanoanthracene. The Probable Involvement of a Thiadioxirane Intermediate in Electron Transfer Photooxygenations
Baciocchi, Enrico,Del Giacco, Tiziana,Elisei, Fausto,Gerini, Maria Francesca,Guerra, Maurizio,Lapi, Andrea,Liberali, Prisca
, p. 16444 - 16454 (2003)
Photooxygenations of PhSMe and Bu2S sensitized by N-methylquinolinium (NMQ+) and 9,10-dicyanoanthracene (DCA) in O 2-saturated MeCN have been investigated by laser and steady-state photolysis. Laser photolysis experiments showed that excited NMQ+ promotes the efficient formation of sulfide radical cations with both substrates either in the presence or in absence of a cosensitizer (toluene). In contrast, excited DCA promotes the formation of radical ions with PhSMe, but not with Bu2S. To observe radical ions with the latter substrate, the presence of a cosensitizer (biphenyl) was necessary. With Bu2S, only the dimeric form of the radical cation, (Bu2S)2 +., was observed, while the absorptions of both PhSMe+. and (PhSMe)2+. were present in the PhSMe time-resolved spectra. The decay of the radical cations followed second-order kinetics, which in the presence of O2, was attributed to the reaction of the radical cation (presumably in the monomeric form) with O2-. generated in the reaction between NMQ. or DCA-. and O 2. The fluorescence quenching of both NMQ+ and DCA was also investigated, and it was found that the fluorescence of the two sensitizers is efficiently quenched by both sulfides (rates controlled by diffusion) as well by O2 (kq = 5.9 × 109 M-1 s-1 with NMQ+ and 6.8 × 10 9 M-1 s-1 with DCA). It was also found that quenching of 1NMQ* by O2 led to the production of 1O2 in significant yield (φΔ = 0.86 in O 2-saturated solutions) as already observed for 1DCA* . The steady-state photolysis experiments showed that the NMQ+- and DCA-sensitized photooxygenation of PhSMe afford exclusively the corresponding sulfoxide. A different situation holds for Bu2S: with NMQ +, the formation of Bu2SO was accompanied by that of small amounts of Bu2S2; with DCA, the formation of Bu 2SO2 was also observed. It was conclusively shown that with both sensitizers, the photooxygenations of PhSMe occur by an electron transfer (ET) mechanism, as no sulfoxidation was observed in the presence of benzoquinone (BQ), which is a trap for O2-., NMQ ., and DCA-.. BQ also suppressed the NMQ +-sensitized photooxygenation of Bu2S, but not that sensitized by DCA, indicating that the former is an ET process, whereas the second proceeds via singlet oxygen. In agreement with the latter conclusion, it was also found that the relative rate of the DCA-induced photooxygenation of Bu2S decreases by increasing the initial concentration of the substrate and is slowed by DABCO (an efficient singlet oxygen quencher). To shed light on the actual role of a persulfoxide intermediate also in ET photooxygenations, experiments in the presence of Ph2SO (a trap for the persulfoxide) were carried out. Cooxidation of Ph2SO to form Ph2SO2 was, however, observed only in the DCA-induced photooxygenation of Bu2S, in line with the singlet oxygen mechanism suggested for this reaction. No detectable amounts of Ph2SO 2 were formed in the ET photooxygenations of PhSMe with both DCA and NMQ+ and of Bu2S with NMQ+. This finding, coupled with the observation that 1O2 and ET photooxygenations lead to different product distributions, makes it unlikely that, as currently believed, the two processes involve the same intermediate, i.e., a nucleophilic persulfoxide. Furthermore, the cooxidation of Ph 2SO observed in the DCA-induced photooxygenation of Bu2S was drastically reduced when the reaction was performed in the presence of 0.5 M biphenyl as a cosensitizer, that is, under conditions where an (indirect) ET mechanism should operate. This observation confirms that a persulfoxide is formed in singlet oxygen but not in ET photosulfoxidations. The latter conclusion was further supported by the observation that also the intermediate formed in the reaction of thianthrene radical cation with KO2, a reaction which mimics step d (Scheme 2) in the ET mechanism of photooxygenation, is an electrophilic species, being able to oxidize Ph2S but not Ph2SO. It is thus proposed that the intermediate involved in ET sulfoxidations is a thiadioxirane, whose properties (it is an electrophilic species) seem more in line with the observed chemistry. Theoretical calculations concerning the reaction of a sulfide radical cation with O 2-. provide a rationale for this proposal.
A Kinetic Study of Sulfide Oxidation by Sodium Hypochlorite Using Phase-Transfer Catalysis
Ramsden, James H.,Drago, Russell S.,Riley, Richard
, p. 3958 - 3961 (1989)
The use of sodium hypochlorite as a synthetically useful oxidizing agent is reported for the oxidation of lipophilic organic sulfide substrates employing phase-transfer catalysis (PTC).The PTC results in nearly complete oxidation of the substrate in 20 min, with high selectivity to the sulfoxide, compared to 5 h in its absence.Kinetic studies show the reaction occur via transfer of OCl- into the organic phase.Under certain conditions the transfer is rate limiting.The addition of a transition-metal catalyst (TPPMnCl) further increased the rate and led to the complete conversion of the sulfide to the sulfone, illustrating that NaOCl(aq) is a potent oxidizing agent in these biphasic systems.
4-Benzoylbenzoate intercalated in layered double hydroxides: A new catalyst for photo-oxidation of sulfides in solution and in the gas phase
Pigot, Thierry,Arbitre, Thomas,Martinez, Hervé,Lacombe, Sylvie
, p. 4047 - 4050 (2004)
A new mixed organic-inorganic photosensitizer, based on 4-benzoylbenzoate intercalated into a layered double hydroxide has been prepared, characterized and successfully tested for the photo-oxidation of dialkylsulfides, both in acetonitrile and in the gas phase.
Polyoxometalate LUMO engineering: A strategy for visible-light-responsive aerobic oxygenation photocatalysts
Li, Chifeng,Suzuki, Kosuke,Mizuno, Noritaka,Yamaguchi, Kazuya
, p. 7127 - 7130 (2018)
We report the efficient visible-light-responsive photocatalysis of polyoxometalates (POMs) by engineering the lowest unoccupied molecular orbitals (LUMOs). By the introduction of vanadium atoms into the γ-Keggin-type phosphotungstate, a new V3d/W5d mixed LUMO appeared to afford a visible-light-responsive catalyst (I), which showed high photocatalytic activity for aerobic oxygenation of sulfides to sulfoxides.
A mild and chemoselective CALB biocatalysed synthesis of sulfoxides exploiting the dual role of AcOEt as solvent and reagent
Anselmi, Silvia,Liu, Siyu,Kim, Seong-Heun,Barry, Sarah M.,Moody, Thomas S.,Castagnolo, Daniele
supporting information, p. 156 - 161 (2021/01/14)
A mild, chemoselective and sustainable biocatalysed synthesis of sulfoxides has been developed exploiting CALB and using AcOEt with a dual role of more environmentally friendly reaction solvent and enzyme substrate. A series of sulfoxides, including the drug omeprazole, have been synthesised in high yields and with excellent E-factors.
Air atmospheric photocatalytic oxidation by ultrathin C,N-TiO2nanosheets
Cheng, Xiuyan,Zhang, Jianling,Liu, Lifei,Zheng, Lirong,Zhang, Fanyu,Duan, Ran,Sha, Yufei,Su, Zhuizhui,Xie, Fei
supporting information, p. 1165 - 1170 (2021/02/26)
Herein, we demonstrate the highly efficient photocatalytic sulfide oxidation reaction under mild conditions,i.e.in air, at room temperature and in the absence of a sacrificial reagent, co-catalyst or redox mediator, by using ultrathin C,N-TiO2nanosheets as a photocatalyst.
