Polymer-anchored oxovanadium(IV) complex for the oxidation of thioanisole, styrene and ethylbenzene

Tshentu, Zenixole R.; Togo, Chamunorwa; Walmsley, Ryan S.

doi:10.1016/j.molcata.2009.11.004

Cited by 35 publications

(28 citation statements)

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“…[18][19][20][21][22][23][24][25] The activity and selectivity of metal complexes immobilized on polymer microspheres have been reported in our previous studies to be as efficient as unsupported metal complexes. [26][27][28][29] In an attempt to improve the surface area of the polymeric support, electropsun polymer fibres have also been reportedly employed as an alternative. [30][31][32][33] This paper describes the development of oxidovanadium(IV) catalyst immobilized on 2,2'-(1E,1'E)-(1,2-phenylenebis(azan-1-yl-1-ylidene))bis(methan-1-yl-1-ylidene)bis(4-aminophenol)-PVB electrospun nanofibres for the oxidation of dibenzothiophene.…”

Section: Introductionmentioning

confidence: 99%

The oxidation of dibenzothiophene using oxidovanadium(IV)-containing nanofibres as catalyst

OGUNLAJA,

HOSTEN,

TSHENTU

2015

S.Afr.j.chem

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Polyvinylbenzylchloride nanofibres were fabricated by the electrospinning technique and subsequently functionalized with a tetradentate ligand, 2,2'-(1E,1'E)-(1,2-phenylenebis(azan-1-yl-1-ylidene))bis(methan-1-yl-1-ylidene)bis(4-aminophenol). VO 2+ was then incorporated into the nanofibres to produce the catalyst VO-fibres. Microanalysis, TG and FT-IR were used for the characterization of VO-fibre, and EPR also confirmed the presence of oxidovanadium(IV) within the nanofibres. Oxidation of dibenzothiophene (DBT) was investigated by varying the catalyst amount, substrate amount, oxidant and temperature, and the progress of oxidation was followed with a gas chromatograph fitted with a flame ionization detector. An increase in the amount of oxidant caused an increase in the amount of dibenzothiophene sulfone (DBTO 2 ), while a decrease in the quantity of dibenzothiophene resulted in an increase in the overall yield of dibenzothiophene sulfone under a constant temperature and oxidant (H 2 O 2 ) concentration. Dibenzothiophene sulfone was confirmed as the oxidation product through 1 H-NMR spectroscopy and single crystal X-ray diffraction. KEYWORDSVanadium(IV) catalyst, nanofibres, dibenzothiophene, oxidation, hydrogen peroxide (H 2 O 2 ).

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Section: Introductionmentioning

confidence: 99%

The oxidation of dibenzothiophene using oxidovanadium(IV)-containing nanofibres as catalyst

OGUNLAJA,

HOSTEN,

TSHENTU

2015

S.Afr.j.chem

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“…The interest specifically stemsfromthe potentialapplication of suchsulfurcontaining entitiesinthe process of preparingcompounds of biologicalimportance [1] as well as from potential applications in the desulfurization of crudeoil in industrial-scale petrochemicalindustry processes [ 2].Ap romising pathway in this contexti s researchdone on the field of polymer-bound oxidovanadium species [3][4][5][6][7]. In the wake of testing the effectiveness of one of our catalysts with oxidizing methylphenylsulfide, the title compound wasobtained.Toascertainthe chemicalcomposition of the productand confirm the effected mono-oxidation, its crystal structure wasdetermined.…”

Section: Discussionmentioning

confidence: 99%

Crystal structure of methylphenylsulfoxide, C7H8OS

Hosten

Tshentu

Betz

2014

Zeitschrift Für Kristallographie - New Crystal Structures

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Source of materialThec ompoundw as obtained in analogy to the procedures describedinreferences [3-7]. Crystals suitable for the diffraction studywereobtaineduponcooling thereaction productto0°C. Experimental detailsCarbon-boundHatoms were placed in calculated positions(C-H 0.95 Å) andwereincludedinthe refinement in the riding model approximation, with U iso (H) setto1.2U eq (C). The Hatoms of the methyl group were allowed to rotate with afixed angle around the C-C bond to best fit the experimental electron density (HFIX 137 in the SHELX program suite [11]), with U iso (H) setto1.5U eq (C). DiscussionThe development and synthesis of powerful and targeted oxygenation catalysts to convert organic sulfides into sulfoxides and sulfonesh as been af ocus of research in chemistry. The interest specifically stemsfromthe potentialapplication of suchsulfurcontaining entitiesinthe process of preparingcompounds of biologicalimportance[1] as well as from potential applications in the desulfurization of crudeoil in industrial-scale petrochemicalindustry processes [ 2].Ap romising pathway in this contexti s researchdone on the field of polymer-bound oxidovanadium species [3][4][5][6][7]. In the wake of testing the effectiveness of one of our catalysts with oxidizing methylphenylsulfide, the title compound wasobtained.Toascertainthe chemicalcomposition of the productand confirm the effected mono-oxidation, its crystal structure wasdetermined. Thecompound is an asymmetric sulfoxidefeaturing amethyl andaphenyl group bonded to the sulfur atom. The S-O bond length of 1.4938(12) Åisingood agreement-although slightlytowards smallervalues-withothervaluesreported for organic sulfoxides whose structural data wasdeposited with the Cambridge Structural Database [8].The angles aroundthe sulfur atom spanarangeof97.40 (7)-107.18 (7)°with the smallest angle foundinbetween the two organic substituentsand the largest angle apparent in betweenthe oxygen atom and the phenyl group. Theleast-squares planes as defined by the non-hydrogen atomsof the phenyl moiety on the one hand and the O=S-C ar entity on the otherhand intersect at an angle of 16.49(9)°only.Inthe crystal, intermolecularC -H×××Oc ontacts can be observed whose range falls invariably by more than 0.1 Åb elow the sum of van-derWaals radii of the atoms participatinginthem. These are exclusively supported by hydrogen atomso ft he methyl group. The oxygen atom serves as two-fold acceptor but could be discussed to be the end point of athird C-H×××Ocontact, the latter one being an intramolecular onestemming from ahydrogen atom in ortho position on the aromatic substituent. This could explain the small torsional angle as mentioned above for the intersection of the least-suqaresp lanes. In total, them olecules are connected to planes perpendiculart ot he crystallographic c axis.I nt erms of graph-seta nalysis[ 9, 10],t he descriptor for these contacts is S(5)C 1 1 (4)C 1 1 (4) on the unary level. The shortest intercentroid distance between two centers of gravity was found at 4.9447(10) Åruling ...

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“…The ligands chosen in this study were based on the 2-(2 0 -hydroxyphenyl)-1H-imidazoline ligand used in our previous work [10] with two major exceptions. Two extra phenyl groups were added to provide additional stability through p-p interactions with polystyrene [23] and the substituent at the para-position of the phenol ring was varied to assess the effect of electron withdrawing/donating groups on the catalytic activity.…”

Section: Synthesis and Characterization Of Catalystsmentioning

confidence: 99%

“…Current economical and environmental concerns make hydrogen peroxide an attractive option due to its low cost and lack of harmful by-products, respectively [8]. Combining hydrogen peroxide with a transition metal catalyst provides further benefits including a reduced reaction time [9,10], as well as the ability to manipulate product selectivity and chirality [11]. The use of vanadium catalysts for the oxidation of sulfides has attracted much interest in this regard.…”

Section: Introductionmentioning

confidence: 99%

“…This is possibly due to the difficulty and expense of recovering homogeneous catalysts from the reaction solution. There are several materials that have proven to be useful supports for immobilizing vanadium catalysts, one of which is micro-spherical polystyrene-based resins [10][11][12]. These resins can be easily functionalized to provide sites for subsequent ligand and metal attachment.…”

Section: Introductionmentioning

confidence: 99%

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Towards the Development of Fiber-Based Oxidovanadium(IV) Catalysts for the Oxidation of Thioanisole

et al. 2011

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The catalytic activity of a series of bis-coordinated oxidovanadium(IV) complexes with 2-(4,5-diphenyl-1H-imidazol-2-yl)-4R-phenol ligands (R = NO 2 , Br, H, MeO) was investigated for the oxidation of thioanisole by hydrogen peroxide in acetonitrile at 25°C. The substituent groups had a significant effect on the catalytic activity and followed the order NO 2 [ Br [ H [ MeO, with the nitro (NO 2 ) derivative achieving [99% conversion after 10 min while the methoxy (MeO) derivative yielded the same result in 60 min. The nitro-and methoxy-substituted homogeneous catalysts were incorporated into polystyrene and electrospun to form nonwoven mats with fiber diameters in the range 0.33-1.98 lm. These vanadium incorporated fibers were subjected to a continuous flow system at a flow rate of 1 mL/h for the oxidation of thioanisole and the nitro-substituted catalyst showed excellent catalytic activity with conversions dropping from 99 to 93% in the 10th fraction while the drop was down to 88% for the methoxy-substituted catalyst.

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Polymer-anchored oxovanadium(IV) complex for the oxidation of thioanisole, styrene and ethylbenzene

Cited by 35 publications

References 20 publications

The oxidation of dibenzothiophene using oxidovanadium(IV)-containing nanofibres as catalyst

The oxidation of dibenzothiophene using oxidovanadium(IV)-containing nanofibres as catalyst

Crystal structure of methylphenylsulfoxide, C7H8OS

Towards the Development of Fiber-Based Oxidovanadium(IV) Catalysts for the Oxidation of Thioanisole

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