Research Article Preparation of Mesoporous SBA-16 Silica …downloads.hindawi.com/journals/jnm/2014/123680.pdf · 2019-07-31 · Research Article Preparation of Mesoporous SBA-16

Research ArticlePreparation of Mesoporous SBA-16 Silica-SupportedBiscinchona Alkaloid Ligand forthe Asymmetric Dihydroxylation of Olefins

Shaheen M Sarkar1 Md Eaqub Ali2 Md Lutfor Rahman1 and Mashitah Mohd Yusoff1

1 Faculty of Industrial Sciences and Technology University Malaysia Pahang 26300 Gambang Kuantan Malaysia2 Nanotechnology and Catalysis Research Centre (NanoCat) University of Malaya Level 3 Block A IPS Building50603 Kuala Lumpur Malaysia

Correspondence should be addressed to Md Eaqub Ali eaqubaligmailcom

Received 21 March 2014 Revised 20 May 2014 Accepted 21 May 2014 Published 15 June 2014

Academic Editor Daniela Predoi

Copyright copy 2014 Shaheen M Sarkar et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

Optically active cinchona alkaloid was anchored onto mesoporous SBA-16 silica and the as-prepared complex was used as aheterogeneous chiral ligand of osmium tetraoxide for the asymmetric dihydroxylation of olefins The prepared catalytic systemprovided 90ndash93 yield of vicinal diol with 92ndash99 enantioselectivity The ordered mesoporous SBA-16 silica was found to be avaluable support for the cinchona alkaloid liganded osmium catalyst system which is frequently used in chemical industries andresearch laboratories for olefin functionalization

1 Introduction

The discovery of highly ordered mesoporous materials hasopened up new fields of research in advanced chemistrymodern electronics and nanotechnology [1ndash3] Orderedmesoporous SBA-16 is a nanostructured porous materialwith a 3D cubic arrangement of mesopores that correspondsto the Im3m space group [4ndash9] The surface properties ofsuch materials could be significantly modified by addingorganic groups and various functionalities onto them [10]Our interest in the field led us to prepare SBA-16 silica-supported biscinchona alkaloid for osmium-catalyzed asym-metric dihydroxylation (AD) of olefins Osmium-catalyzedasymmetric dihydroxylation of olefins is an attractivemethodfor the synthesis of optically active diols [11ndash14] Cinchonaalkaloid-based osmium complexes are harmless and knownto be the most effective chiral catalysts for AD reactions interms of both reactivity and enantioselectivity [15ndash18]

However the high cost and toxicity of osmium are aserious concern and many efforts have been devoted to over-come the issue including the development of heterogeneouscatalyst ligand to trap the osmium [19 20] Immobilization

of homogeneous catalysts onto various supports has emergedas a major route to prepare heterogeneous catalysts [2122] Such a heterogeneous catalyst system offers practicaladvantages in catalyst separation and potential recyclingover its homogeneous counterpart [23 24] Silica gel suchas mesoporous silica MCM-41 and SBA-15 has been suc-cessfully used as inorganic supports for the immobilizationof homogeneous catalysts [25ndash27] However despite havinghighly ordered mesopores SBA-16 silica has been scarcelyexplored in this area Herein we described the synthesis ofSBA-16 supported cinchona alkaloid ligand and tested it forthe osmium catalyzed AD reaction of olefins to diols a keyreaction in organic synthesis

2 Experimental Details

21 Preparation of the SBA-16 Silica SBA-16 silica wassynthesized at room temperature under acidic conditionusing Pluronic F127 (EO

106PO70EO106

119872119908= 126K) as

a structure-directing agent (SDA) [28] The acidic solutionwas made by adding 15 g of deionized (DI) water to 120 g of

Hindawi Publishing CorporationJournal of NanomaterialsVolume 2014 Article ID 123680 5 pageshttpdxdoiorg1011552014123680

2 Journal of Nanomaterials

NNClCl

N

MeO

MeO

MeO

NOH

N

NO

NN

N

OMe

OMe

NO

N

NO

NN

N

NO

SS

N

MeO

NO

NN

N

OMe

NO

S SiSSiOOO

O

OO

4 3

2

1

THF NaH

(EtO)3Si Si(OEt)3

(EtO)3Si(CH2)3SHAIBN CHCl3Reflux 36 h

TolueneReflux 12 h

SBA-16 silica

SBA-16SBA-16

0sim60∘C 2 h

Scheme 1 Preparation of SBA-16-supported biscinchona alkaloid 1

2MHCl solution at room temperature Subsequently 85 g oftetraethoxysilane (TEOS) was added onto the solution andstirring continued for 20 h The reaction mixture was keptat 100∘C for 48 h During this time the solid SBA-16 wasproduced under static conditions in a Teflon-lined vesselThe solid product was recovered and washed with DI waterCalcination was carried out slowly by increasing temperaturefrom room temperature to 500∘C in 8 h and heating at 500∘Cfor another 6 h

22 Preparation of the 14-Bis(9-O-quininyl)phthalazine 3NaH (224mmol) at 0∘C was slowly added to a stirredsolution of 14-dichlorophthalazine (05mmol) and quinine 4(115mmol) in THF (8mL) The solution was stirred at 60∘Cfor 2 h and then it was quenched at 0∘C by careful addition ofwaterThemixture was extracted in ethyl acetate (EtOAc) andthe solvent was removed under reduced pressureThe residuewas purified by short column chromatography to separate 14-bis(9-O-quininyl)phthalazine 3 and 82 yield was obtained

23 Preparation of the Triethoxysilanized 14-Bis(9-O-quin-inyl)phthalazine 2 14-Bis(9-O-quininyl)phthalazine 3(05mmol) was added to a solution of (3-mercapto-propyl)triethoxysilane (125mmol) and 1205721205721015840-azoisobutyronitrile(AIBN) (010mmol) in degassed chloroform (10mL) underN2atmosphere The reaction mixture was refluxed for 30 h

and concentrated under reduced pressure The residue waspurified by flash short column on silica gel to give compound2 with 80 yield

24 Immobilization of Biscinchona Alkaloid 2 onto SBA-16 Silica 1 SBA-16 silica (10 g) was suspended in tolueneand refluxed with compound 2 (145mg 0124mmol) After12 h the powder was collected by filtration and washedwith methanol and methylene chloride After drying undervacuum at 70∘C SBA-16-supported alkaloid 1 (1077 g)was obtained Elemental analysis and weight gain showedthat 0073mmol of 14-bis(9-O-quininyl)phthalazine wasanchored on 10 g of SBA-16-supported chiral Ligand 1

25 Characterization of SBA-16-Supported Chiral Ligand 1Powder X-ray diffractometry (Philips PW 1729) was usedfor the determination of crystalline structure using CuKaradiation over 05∘ le 2120579 le 3 The XRD sample of SBA-16was analyzed at 30∘C The diffractograms showed 3 peaks at2120579 asymp 074

∘ 11∘ and 14∘ that corresponded to (110) (200)and (211) planes respectively in the cubic Im3m structureThe transmission electronmicroscopy (TEM)was performedwith a FEI Tecnai G2 microscope operated at 200 kV TheTEM sample was prepared by placing a few drops of SBA-16powder dispersed in acetone on a carbon grid and allowingit to dry for 5min before TEM analysis Large particles werecrushed by submerging them in liquid nitrogen followed bymechanical grinding in a mortar prior to acetone dispersionThenitrogen adsorption-desorptionmeasurementswere per-formed at minus196∘C on a Micromeritics ASAP 2020 surfacearea and porosity analyzer Approximately 05 g of SBA-16wasdegassed at 300∘C for 9 h before taking themeasurementThesurface area determination was performed by the Brunauer-Emmett-Teller (BET) method [29] over the relative pressure

Journal of Nanomaterials 3

(1198751198750) range of 005ndash02 The pore-size distribution was

determined using the Broekhoff-de Boer (BdB) method [30]applied to the adsorption branch Finally the total porevolume was calculated from the amount of adsorbed N

2at

1198751198750= 099 and the microporous volume was determined

using the 119905-plot method

26 Asymmetric Dihydroxylation of Olefin Using SBA-16-Supported Chiral Ligand 1 A mixture of SBA-16-supportedbiscinchona alkaloid 1 (1mol) potassium ferricyanide(15mmol) potassium carbonate (15mmol) and OsO

4

(1mol 05M in water) in tert-butyl alcohol-water (6mL1 1 vv) was stirred at room temperature for 30min Olefin(05mmol) was added at once and stirred for 7sim15 h Thereaction mixture was diluted with water and CH

2Cl2and the

immobilized Ligand 1 was separated by filtration The crudeproduct was purified by flash column chromatography andthe enantiomeric excess of the diol was determined by chiralgas chromatography (GC) analysis (Agilent HP Chiral-20B30MX025MMX025UM GC Column)

3 Results and Discussion

To synthesize a SBA-16-supported biscinchona alkaloid 1 westarted with quinine and 14-dichlorophthalazine following aroute shown in Scheme 1

Treatment of optically active quinine 4 with 14-dichlo-rophthalazine in the presence of excess NaH synthesized4-bis(9-O-quininyl)phthalazine 3 with high yield (82)Radical reaction of dimeric quinine 3 with (3-mercap-topropyl)triethoxysilane in the presence of AIBN radicalinitiator provided compound 2 having a pendant triethoxysi-lane functional group The desired immobilized biscinchonaalkaloid SBA-16 1 (loading ratio 0073mmolg) was readilyobtained by condensation of 2with surface silanols of SBA-16support in refluxing toluene The degree of functionalizationwas determined by elemental analysis and weight gain Asshown in Table 1 the surface area and pore diameter weredecreased following the modification The high resolutiontransmission electron microscopy (HRTEM) image of SBA-16-supported Ligand 1 is shown in Figure 1 The 3D cubicstructure and the pore arrays were conserved after the immo-bilization of 14-bis(9-O-quininyl)phthalazine onto SBA-16silica and it was also confirmed by XRD (Figure 2)

The AD reaction of stilbene was performed in thepresence of immobilized cinchona alkaloid 1 (1mol) andOsO4(1mol) at room temperature Potassium carbonate

and potassium ferricyanide were used as a secondary oxidantin tert-butyl alcohol-water mixture (1 1) The results aresummarized in Table 2 Surprisingly catalytic AD reactionsof stilbene provided excellent enantioselectivities and highyields (entries 1 and 2) Osmium catalyst loading of 05molwas sufficient to obtain outstanding enantioseletivity as wellas high reactivity Moreover the SBA-16-supported alkaloid-OsO4complex could be reused for the AD reaction of

stilbene without a significant loss of reactivity and enantios-electivity (entry 3) The catalyst was also highly effective to

Figure 1 HRTEM image of SBA-16-supported Ligand 1

1 2 3 4 5

0

1

2

3

4

5

6

Inte

nsity

Parent SBA-16

SBA-16-supported Ligand 1

110

200

211

times104

2120579

Figure 2 XRD pattern of SBA-16-supported Ligand 1

ADofmethylcinnamate 1-phenyl-1-cyclohexene and styrene(entries 4ndash6)

The SBA-16-supported Ligand 1 reported here showedsomewhat higher reactivity and better asymmetric inductionover amorphous silica-supported biscinchona alkaloid [25]The improved outcome of the reaction seems to be attributedto the ordered array of chiral catalytic site on the nanoporesurface of SBA-16 support The ordered array leads to elegantsite isolationwhichmay result in enhanced enantioselectivity

Romero et al [31] reported the asymmetric dihydroxy-lation reaction of olefin using ionic liquid which involveshigh cost and toxicity The yield and enantioselectivity of thestyrene were also very poor (87 yield 62 ee) [32] On theother hand Junttila and Hormi [33] used methanesulfon-amide as an accelerator of the asymmetric dihydroxylationreaction using potassium osmate (vi) and obtained 97 eewith low yield (70) of the diol product It is noteworthy herethat the alkaloid ligand complexes synthesized in this reportproduced excellent results in terms of both yield (93) andenantioselectivity (92ndash99)


Table 1 Structural characteristics of SBA-16-supported Ligand 1

Sample Surface area Pore diameter Pore volume Functional groupSBA-16 820m2g 513 nm 073 cm3g mdash1 490m2g 368 nm 045 cm3g 0073mmolg

Table 2 Heterogeneous AD of olefins using SBA-16-supported Ligand 1a

R ROH

OH

lowastlowastLigand 1

OsO4 K3Fe(CN)6K2CO3 t-BuOH-H2O

Entry Olefin Time (h) Yield () () Eeb Configb

1 7 93 gt99 S S

2c 7 91 98 S S

3d 8 90 97 S S

4CO2Me

9 91 96 2R 3S

5 10 92 94 2S 3S

6 15 92 92 S

aThe reactions were carried out at RT molar ratio of olefinOsO4supported ligand = 1001001 bEe and absolute configuration were determined by chiralGC analysis cMolar ratio of olefinOsO4supported ligand = 100050005 dReaction was carried out with regenerated 1 without further addition of OsO4

4 Conclusion

We successfully synthesized air and moisture stable SBA-16-supported biscinchona alkaloid chiral ligand Osmiumtetraoxide readily formed a chiral complex with the SBA-16-supported biscinchona alkaloid at room temperatureThe synthesized SBA-16 supported Os-complex efficientlypromoted the asymmetric dihydroxylation of olefin to corre-sponding diols with 92ndash99 enantioselectivity and 93 yielddemonstrating SBA-16 silica as an excellent support materialfor the heterogeneous chiral ligand

Conflict of Interests

The authors declare that they have no conflict of interestsregarding the publication of this paper

Acknowledgment

This work was supported by University of Malaya fund noRP005A-13AET to M E Ali

References

[1] A Corma ldquoFrom microporous to mesoporous molecular sievematerials and their use in catalysisrdquo Chemical Reviews vol 97no 6 pp 2373ndash2420 1997

[2] U Ciesla and F Schuth ldquoOrdered mesoporous materialsrdquoMicroporous and Mesoporous Materials vol 27 no 2-3 pp 131ndash149 1999

[3] A Taguchi and F Schuth ldquoOrdered mesoporous materials incatalysisrdquoMicroporous and Mesoporous Materials vol 77 no 1pp 1ndash45 2005


[4] Y K Hwang J-S Chang Y-U Kwon and S-E Park ldquoMicro-wave synthesis of cubicmesoporous silica SBA-16rdquoMicroporousand Mesoporous Materials vol 68 no 1ndash3 pp 21ndash27 2004

[5] R A Fernandes and A K Chowdhury ldquoStereoselective totalsynthesis of (+)-nephrosteranic acid and (+)-roccellaric acidthrough asymmetric dihydroxylation and JohnsonndashClaisenrearrangementrdquo European Journal of Organic Chemistry vol2011 no 6 pp 1106ndash1112 2011

[6] D Yamashita Y Murata N Hikage K-I Takao A Nakazakiand S Kobayashi ldquoTotal synthesis of (-)-norzoanthaminerdquoAngewandte ChemiemdashInternational Edition vol 48 no 8 pp1404ndash1406 2009

[7] P Gao Z Tong H Hu et al ldquoSynthesis of (+)-9a-epi-stemoam-ide via DBU-catalyzedmichael addition of nitroalkanerdquo Synlettno 13 pp 2188ndash2190 2009

[8] C Yu B Tian J Fan G D Stucky and D Zhao ldquoNonionicblock copolymer synthesis of large-pore cubic mesoporoussingle crystals by use of inorganic saltsrdquo Journal of the AmericanChemical Society vol 124 no 17 pp 4556ndash4557 2002

[9] Y Sakamoto M Kaneda O Terasaki et al ldquoDirect imaging ofthe pores and cages of three-dimensional mesoporous materi-alsrdquo Nature vol 408 no 6811 pp 449ndash453 2000

[10] N Md Alam S M Sarkar and R Md Miah ldquoHeteroge-neous Heck reaction catalysed by silica gel-supported 12-diaminocyclohexane-Pd complexrdquo Reaction Kinetics and Catal-ysis Letters vol 98 no 2 pp 383ndash389 2009

[11] E N Jacobsen A Pfaltz and H Yamamoto in ComprehensiveAsymmetric Catalysis II Springer Berlin Germany 1999

[12] D J Smaltz and A GMyers ldquoScalable synthesis of enantiomer-ically pure syn-23-dihydroxybutyrate by sharpless asymmetricdihydroxylation of p-phenylbenzyl crotonaterdquo The Journal ofOrganic Chemistry vol 76 no 20 pp 8554ndash8559 2011

[13] J Peed I R Davies L R Peacock J E Taylor G K Kohn andSD Bull ldquoDihydroxylation-based approach for the asymmetricsyntheses of hydroxy-120574-butyrolactonesrdquoThe Journal of OrganicChemistry vol 77 no 1 pp 543ndash555 2012

[14] M X Zhao H L Bi H Zhou H Yang and M Shi ldquoCin-chona alkaloid squaramide catalyzed enantioselective hydraz-inationcyclization cascade reaction of 120572-isocyanoacetatesand azodicarboxylates synthesis of optically active 124-triazolinesrdquo The Journal of Organic Chemistry vol 78 p 93772013

[15] H C Kolb M S VanNieuwenhze and K B Sharpless ldquoCat-alytic asymmetric dihydroxylationrdquo Chemical Reviews vol 94no 8 pp 2483ndash2547 1994

[16] H Salim and O Piva ldquoA short access to 3-hydroxy-4-hydroxymethyltetrahydrofurans application to the total syn-thesis of amphiasterin B4rdquo The Journal of Organic Chemistryvol 74 no 5 pp 2257ndash2260 2009

[17] G-B Ren and Y Wu ldquoEnantioselective total synthesis andcorrection of the absolute configuration ofmegislactonerdquoTetra-hedron vol 64 no 19 pp 4408ndash4415 2008

[18] X Huo X Ren Y Xu X Li X She and X Pan ldquoEnan-tioselective total synthesis of hydramicromelin Brdquo TetrahedronAsymmetry vol 19 no 3 pp 343ndash347 2008

[19] L L Lazarusa and R L Brutchey ldquoHeterogeneous fulle-rene-supported osmium tetroxide catalyst for the cis-dihy-droxylation of olefinsrdquo Dalton Transactions vol 39 pp 7888ndash7890 2010

[20] R Cano J M Perez and D J Ramon ldquoOsmium impreg-nated on magnetite as a heterogeneous catalyst for the syn-dihydroxylation of alkenesrdquo Applied Catalysis A General vol470 pp 177ndash182 2004

[21] S M Sarkar N Md Alam and R Md Miah ldquoHighly efficientsilica gel-supported 12-diaminocyclohexane-Pd catalyst forSuzuki-Miyaura and Sonogashira coupling reactionsrdquo ReactionKinetics and Catalysis Letters vol 96 no 1 pp 175ndash183 2009

[22] N Md Alam and S M Sarkar ldquoMesoporous MCM-41 sup-ported N-heterocyclic carbene-Pd(II) complex for Suzuki cou-pling reactionrdquo Reaction Kinetics Mechanisms and Catalysisvol 103 no 2 pp 493ndash500 2011

[23] M S Sarkar H Qiu and M-J Jin ldquoEncapsulation of Pdcomplex in ionic liquid on highly ordered mesoporous silicaMCM-41rdquo Journal of Nanoscience and Nanotechnology vol 7no 11 pp 3880ndash3883 2007

[24] H Qiu S M Sarkar H Do Lee and M J Jin ldquoHighly effectivesilica gel-supported N-heterocyclic carbene-Pd catalyst forSuzuki-Miyaura coupling reactionrdquo Green Chemistry vol 10pp 37ndash40 2008

[25] C E Song J W Yang and H-J Ha ldquoSilica gel supported bis-cinchona alkaloid a highly efficient chiral ligand for hetero-geneous asymmetric dihydroxylation of olefinsrdquo TetrahedronAsymmetry vol 8 no 6 pp 841ndash844 1997

[26] S H Kim andM J Jin ldquoAsymmetric dihydroxylation catalyzedby MCM-41 silica-supported bis-cinchona alkaloidrdquo Studies inSurface Science and Catalysis vol 146 pp 677ndash680 2003

[27] H M Lee S-W Kim T Hyeon and B M Kim ldquoAsymmetricdihydroxylation using heterogenized cinchona alkaloid ligandson mesoporous silicardquo Tetrahedron Asymmetry vol 12 no 11pp 1537ndash1541 2001

[28] D Zhao Q Huo J Feng B F Chmelka and G D StuckyldquoNonionic triblock and star diblock copolymer and oligomericsufactant syntheses of highly ordered hydrothermally stablemesoporous silica structuresrdquo Journal of the American ChemicalSociety vol 120 no 24 pp 6024ndash6036 1998

[29] S Brunauer P H Emmett and E Teller ldquoAdsorption of gasesin multimolecular layersrdquo Journal of the American ChemicalSociety vol 60 no 2 pp 309ndash319 1938

[30] W W Lukens Jr P Schmidt-Winkel D Zhao J Feng andG D Stucky ldquoEvaluating pore sizes in mesoporous materialsa simplified standard adsorption method and a simplifiedBroekhoff-de Boermethodrdquo Langmuir vol 15 no 16 pp 5403ndash5409 1999

[31] A Romero A Santos J Tojo and A Rodrıguez ldquoToxicityand biodegradability of imidazolium ionic liquidsrdquo Journal ofHazardous Materials vol 151 no 1 pp 268ndash273 2008

[32] L C Branco and C AM Afonso ldquoIonic liquids as a convenientnew medium for the catalytic asymmetric dihydroxylation ofolefins using a recoverable and reusable osmiumligandrdquo TheJournal of Organic Chemistry vol 69 no 13 pp 4381ndash43892004

[33] M H Junttila and O O E Hormi ldquoMethanesulfonamide acosolvent and a general acid catalyst in sharpless asymmetricdihydroxylationsrdquo Journal of Organic Chemistry vol 74 no 8pp 3038ndash3047 2009

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CoatingsJournal of

Advances in

Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Smart Materials Research



MetallurgyJournal of


BioMed Research International

MaterialsJournal of


Nano

materials


Journal ofNanomaterials


NNClCl

N

MeO

MeO

MeO

NOH

N

NO

NN

N

OMe

OMe

NO

N

NO

NN

N

NO

SS

N

MeO

NO

NN

N

OMe

NO

S SiSSiOOO

O

OO

4 3

2

1

THF NaH

(EtO)3Si Si(OEt)3

(EtO)3Si(CH2)3SHAIBN CHCl3Reflux 36 h

TolueneReflux 12 h

SBA-16 silica

SBA-16SBA-16

0sim60∘C 2 h

Scheme 1 Preparation of SBA-16-supported biscinchona alkaloid 1

2MHCl solution at room temperature Subsequently 85 g oftetraethoxysilane (TEOS) was added onto the solution andstirring continued for 20 h The reaction mixture was keptat 100∘C for 48 h During this time the solid SBA-16 wasproduced under static conditions in a Teflon-lined vesselThe solid product was recovered and washed with DI waterCalcination was carried out slowly by increasing temperaturefrom room temperature to 500∘C in 8 h and heating at 500∘Cfor another 6 h

22 Preparation of the 14-Bis(9-O-quininyl)phthalazine 3NaH (224mmol) at 0∘C was slowly added to a stirredsolution of 14-dichlorophthalazine (05mmol) and quinine 4(115mmol) in THF (8mL) The solution was stirred at 60∘Cfor 2 h and then it was quenched at 0∘C by careful addition ofwaterThemixture was extracted in ethyl acetate (EtOAc) andthe solvent was removed under reduced pressureThe residuewas purified by short column chromatography to separate 14-bis(9-O-quininyl)phthalazine 3 and 82 yield was obtained

23 Preparation of the Triethoxysilanized 14-Bis(9-O-quin-inyl)phthalazine 2 14-Bis(9-O-quininyl)phthalazine 3(05mmol) was added to a solution of (3-mercapto-propyl)triethoxysilane (125mmol) and 1205721205721015840-azoisobutyronitrile(AIBN) (010mmol) in degassed chloroform (10mL) underN2atmosphere The reaction mixture was refluxed for 30 h

and concentrated under reduced pressure The residue waspurified by flash short column on silica gel to give compound2 with 80 yield

24 Immobilization of Biscinchona Alkaloid 2 onto SBA-16 Silica 1 SBA-16 silica (10 g) was suspended in tolueneand refluxed with compound 2 (145mg 0124mmol) After12 h the powder was collected by filtration and washedwith methanol and methylene chloride After drying undervacuum at 70∘C SBA-16-supported alkaloid 1 (1077 g)was obtained Elemental analysis and weight gain showedthat 0073mmol of 14-bis(9-O-quininyl)phthalazine wasanchored on 10 g of SBA-16-supported chiral Ligand 1

25 Characterization of SBA-16-Supported Chiral Ligand 1Powder X-ray diffractometry (Philips PW 1729) was usedfor the determination of crystalline structure using CuKaradiation over 05∘ le 2120579 le 3 The XRD sample of SBA-16was analyzed at 30∘C The diffractograms showed 3 peaks at2120579 asymp 074

∘ 11∘ and 14∘ that corresponded to (110) (200)and (211) planes respectively in the cubic Im3m structureThe transmission electronmicroscopy (TEM)was performedwith a FEI Tecnai G2 microscope operated at 200 kV TheTEM sample was prepared by placing a few drops of SBA-16powder dispersed in acetone on a carbon grid and allowingit to dry for 5min before TEM analysis Large particles werecrushed by submerging them in liquid nitrogen followed bymechanical grinding in a mortar prior to acetone dispersionThenitrogen adsorption-desorptionmeasurementswere per-formed at minus196∘C on a Micromeritics ASAP 2020 surfacearea and porosity analyzer Approximately 05 g of SBA-16wasdegassed at 300∘C for 9 h before taking themeasurementThesurface area determination was performed by the Brunauer-Emmett-Teller (BET) method [29] over the relative pressure




2at




4


2Cl2and the









1 2 3 4 5

0

1

2

3

4

5

6

Inte

nsity

Parent SBA-16


110

200

211

times104

2120579









R ROH

OH




1 7 93 gt99 S S

2c 7 91 98 S S

3d 8 90 97 S S

4CO2Me

9 91 96 2R 3S

5 10 92 94 2S 3S

6 15 92 92 S


4 Conclusion




Acknowledgment


References










































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials






2at




4


2Cl2and the









1 2 3 4 5

0

1

2

3

4

5

6

Inte

nsity

Parent SBA-16


110

200

211

times104

2120579









R ROH

OH




1 7 93 gt99 S S

2c 7 91 98 S S

3d 8 90 97 S S

4CO2Me

9 91 96 2R 3S

5 10 92 94 2S 3S

6 15 92 92 S


4 Conclusion




Acknowledgment


References










































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials







R ROH

OH




1 7 93 gt99 S S

2c 7 91 98 S S

3d 8 90 97 S S

4CO2Me

9 91 96 2R 3S

5 10 92 94 2S 3S

6 15 92 92 S


4 Conclusion




Acknowledgment


References










































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials









































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials










CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials



Documents

Research Article Preparation of Mesoporous SBA-16 Silica …downloads.hindawi.com/journals/jnm/2014/123680.pdf · 2019-07-31 · Research Article Preparation of Mesoporous SBA-16