Nanorod-Shaped Basic Al2O3 Catalyzed N,N-Diformylation of ...downloads.hindawi.com › journals ›...

Hindawi Publishing CorporationISRN Organic ChemistryVolume 2013 Article ID 793159 6 pageshttpdxdoiorg1011552013793159

Research ArticleNanorod-Shaped Basic Al2O3 Catalyzed NN-Diformylation ofBisuracil Derivatives A Greener lsquolsquoNOSErsquorsquo Approach

Vijay K Das and Ashim J Thakur

Department of Chemical Sciences Tezpur University (A Central University) Napaam Assam 784028 India

Correspondence should be addressed to Ashim J Thakur ajttezu03gmailcom

Received 14 May 2013 Accepted 10 June 2013

Academic Editors R Pohl and D Semeril

Copyright copy 2013 V K Das and A J Thakur 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

A feasible ldquoNOSErdquo (nanoparticles-catalyzed organic synthesis enhancement) protocol has been developed for NN-diformylationof bisuracil derivatives using nano-Al

2O3rods as an efficient inexpensive and recyclable catalyst under solvent-free reaction

condition at 40∘CThe catalyst was reused up to the 4th cycle without affecting the rate and yield of theNN-diformylation productsappreciably

1 Introduction

The exercise of metalmetal oxide nanoparticles as a frontierbetween the homogeneous catalysis and heterogeneous catal-ysis [1] in organic synthesis has invoked tremendous interests[2] in the recent times The interesting features inheritedwith these small particle sizes are their large surface areaalong with more edges and corners and distinct electronicoptical magnetic thermal and chemical properties [3ndash5]The crucial role of nanoparticles in organic transformations istheir excellent catalytic activity straightforward recoverabil-ity better selectivity criteria of evolution and their versatilerole in green chemistry [6ndash10] Thus the domain of metalnanoparticle catalysis [11ndash13] should offer opportunities formining new chemical reactions [14ndash16] which include thesynthesis of biologically important and synthetically chal-lenging natural products In the context of green chemistry[17] organic synthesis in solvent-free reaction condition[18ndash21] has occupied a significant position in the recentyears since solvent-free reaction condition involves the bestreaction medium with ldquono mediumrdquo [22]

One of the key motifs present in the biopolymer RNA[23ndash26] is uracil a nucleobase of the pyrimidine family whichparticipates in various functions in our life processes [27]Uracil derivatives also have several potent medicinal proper-ties such as bronchodilators and anticancer [28 29] antialler-gic [30 31] antiviral [32 33] antihypertensive and adenosinereceptor antagonists [34 35] Recently our research group

reported a greener protocol for the synthesis of bisuracilderivatives [36] Bisuracil and their analogues have also beenisolated from marine sea hare Dolabella auricularia [37]Some of the N-substituted bisuracil analogues have beenscreened for bioactivities against several diseases [38]

To explore the possible applications of the metalmetaloxide nanoparticles in organic synthesis we have beenfocusing on the advancement of a protocol termed ldquoNOSErdquo(nanoparticles-catalyzed organic synthesis enhancement)[39ndash41] chemistry in our laboratory To the best of ourknowledge there has been no report on nano-rod-shapedAl2O3catalyzed NN-diformylation of bisuracil derivatives

Recently we reported N-formylation of amines catalyzed bynano-Al

2O3under solvent-free reaction condition [39] This

work inspired us to focus on nano-Al2O3catalysis for the

NN-diformylation of bisuracil analogous Therefore in thispaper we wish to account for the same (Scheme 1)

Nano-Al2O3draws our attention due to its crystalline size

and shape abrasive and insulating properties less toxicitylarge surface area basic surface characteristics high resistanttowards bases and acids and excellent wear resistance [40ndash44]

2 Materials and Methods

21 General ExperimentalMethods Rod-shaped nano-Al2O3

(the average particle diameter is 812 nm and average length

2 ISRN Organic Chemistry

N

N N

N

O

RO

O O

N

N N

N

O

RO

O OH2N

NH2

HCOOH

Nano-Al2O3 Isolatedand

reused

OHCHN

NHCHO

Me

Me Me Me Me

MeMeMe40

∘C SFRC

2(andashk)1(andashk)

Scheme 1 NN-diformylation of bisuracil derivatives 1(andashk)

N

N N

N

OO O

O

N

N N

N

OO O

O

HCOOH

OHCHN

NHCHO

MeMe

Me

MeMe

Me Me Me

Catalyst

NH2

H2N

1a 2b

Scheme 2 Optimization of reaction condition

255 nm 119878BET = 18563m2 gminus1 120588 = 398 g cmminus3 and purityis 9999) were purchased from Sigma Aldrich and used asreceived The chemicals and reagents were purchased fromSigma-Aldrich Merck MS SD Fine Chemicals Pvt Ltdand Loba Chemie and used without further purificationTheXRD pattern was recorded with Rigaku X-ray diffractometerMelting points were determined in a Buchi 504 apparatus IRspectra were recorded as KBr pallets in a Nicolet (Impact 410)FT-IR spectrophotometer 1H and 13C NMR spectra wererecorded in a 400MHz NMR spectrophotometer (JEOLJNM ECS) using tetramethylsilane (TMS) as the internalstandard and coupling constants are expressed in HertzElemental analyses were carried out in a Perkin-Elmer CHNanalyser (2400 series II) Mass spectra were recorded with aWaters Q-TOF Premier and an Acquity UPLC spectrometerVisualization was accomplished with UV lamp or I

2stain

Reactions were monitored by thin-layer chromatographyusing aluminium sheets with silica gel 60 F

254(Merck)

22 General Procedure for NN-Diformylation of BisuracilDerivatives In a two-neck round bottom flask (50mL)nanorod-shaped basic Al

2O3(70mol 712mg) were taken

and then 1g (10mmol 414mg) and formic acid (9860mmol 023mL) were added After that it was allowedto stir on a pre heated oil bath at 40∘C for the requiredtime (the progress of the reaction was judged by TLC) Thereaction mixture was brought to room temperature after itscompletion and ethyl acetate (3 times 10mL) was added and thencentrifuged (3000 rpm) to recover the nanocatalyst Havingdone this the reaction mixture was washed with water andbrine dried over anhydrous Na

2SO4 and concentrated in a

rotary evaporator and finally the crude product was purifiedby column chromatography (30 ethyl acetate hexane as aneluent) The recovered catalyst was washed with hot ethanol(3 times 10mL) to remove the organic impurities decanted driedin an oven at 80∘C for 6 h and reused for evaluating theperformance in the next run in the reaction as shown inScheme 2

3 Results and Discussion

With the previously reported catalyst characterizations inhand [39] to begin with reaction of 661015840-diamino-111015840331015840-tetramethyl-551015840-(benzylidene)bis[pyrimidine-24 (1H 3H)-dione] [36] (1a 1 mmol) with formic acid (6mmol) waschosen as the model reaction (Scheme 2)

The optimization of the various parameters of this reac-tion is elaborated in Table 1 Initially the reaction wascarried out without using catalyst under solvent-free reactioncondition at 40∘C and 80∘C which did not yield any product(Table 1 entries 1 and 2) Various solvents were also testedunder the mentioned condition but they all failed (Table 1entries 3ndash11) to provide any product These negative resultssuggested that we look for an effective catalyst in the presentstudy Next various Lewis acid-base catalysts (Table 1 entries12ndash14) along with the nanocatalysts (Table 1 entries 15ndash18) were surveyed to observe the influence on rate andyield of NN-diformylation of 1a which were not fruitfulInterestingly nanorod-shaped basic Al

2O3stood out as a

choice of catalyst at 7mol loading (Table 1 entry 15) undersolvent-free reaction condition at 40∘C During the courseof our experiment we observed that at higher temperature

ISRN Organic Chemistry 3

Table 1 Optimization of the reaction conditions for the NN-diformylation of 1a (Scheme 1)

Entry Catalyst Solvent Temp (∘C) Time (h) Yield ()b

1 None Solvent-free 40 9 NRc


3 None H2O 40 12 NRc

4 None CH3CN 40 12 NRc

5 None MeOH 40 12 NRc

6 None EtOH 40 12 NRc

7 None THF 40 12 NRc

8 None Toluene 40 12 NRc

9 None DMSO 40 12 NRc

10 None Xylene 40 12 NRc

11 None DMF 40 12 NRc

12d K2CO3 Solvent-free 40 12 NRc

13d PPh3 Solvent-free 40 12 NRc

14d Imidazole Solvent-free 40 10 Trace15d Nano-Al2O3

i Solvent-free 40 45min 7016d Nano-MgOj Solvent-free 40 3 3417d Nano-Fe2O3

k Solvent-free 40 5 1218d Nano-TiO2

l Solvent-free 40 4 819d Nano-Al2O3

i Solvent-free 80 2 4320e Nano-Al2O3

i Solvent-free 40 3 2521f Nano-Al2O3

i Solvent-free 40 4 1722g Nano-Al2O3

i Solvent-free 40 6 8aReaction conditions bisuracil 1a (1mmol 0454 g) formic acid (6mmol 066mL) and solvent (5mL) bIsolated yields cNo reaction was observed d7molcatalyst was used e5mol catalyst was used f3mol catalyst was used g10mol catalyst was used h1mol catalyst was used iParticles size (174ndash164 nm)jParticles size (lt50 nm) kParticles size (12 nm) lParticles size (lt80 nm)

Table 2 Nano-Al2O3 catalyzed NN-diformylation of uracil and bisuracil derivatives

Entry ldquoRrdquo in 1 Product 2 Time (min) Yield ()ab

1 C6H5 (1a) 2a 45 702 p-OMeC6H4 (1b) 2b 60 683 p-ClC6H4 (1c) 2c 75 584 p-OHC6H4 (1d) 2d 90 555 p-NO2C6H4 (1e) 2e 90 526 p-MeC6H4 (1f) 2f 70 607 o-OHC6H4 (1g) 2g 100 528 m-NO2C6H4 (1h) 2h 90 659 CH3 (1i) 2i 100 5210 CH3(CH2)3(1j) 2j 120 4411 2-furyl (1k) 2k 150 57a6mmol of formic acid was used bIsolated yield cProducts were characterized by IR and NMR (1H and 13C) spectroscopy MS and also melting points

Table 3 Recycling study of nano-Al2O3

Entry No of cycles Time (min) Yield ()b TONs1 Fresh 45 70 882 1st run 45 70 883 2nd run 45 70 884 3rd run 45 70 885 4th run 45 70 886 5th run 60 58 767 6th run 180 40 70aReaction conditions 2mmol of 2b 12mmol formic acid and 7mol basic nano-Al2O3 40

∘C bYields refer to the isolated pure products


240220200180160140120100

80604020

010 20 30 40 50 60 70 80 90

Inte

nsity

(cou

nts)

2120579 (scale)

100

400

6th reused

5th reused

4th reused

3rd reused

Fresh nano-Al2O3

Figure 1 Comparison of XRD of fresh nano-Al2O3with the

recovered ones

(Table 1 entry 19) and at lowerhigher catalyst loading theyield of the products was poor (Table 1 entries 20ndash22)Thus the yield of NN-diformylation product of bisuracilderivatives is highly dependent upon the temperature andcatalyst loading

With this supportive optimized reaction condition inhand a series of bisuracil derivatives (entries 1ndash11) bearingdifferent aliphatic aromatic and heterocyclic moieties wereexamined to explore the scope and limitations of this reactionand the outcomes are presented in Table 2 It is clear fromTable 2 that bisuracil derivatives carrying both electrondonating and electron withdrawing groups in benzene ringunderwent NN-diformylation reaction smoothly producinggood yields (Table 2 entries 1ndash8) However longer reactiontime was required for bisuracil derivatives substituted withfuran and alkyl groups (Table 2 entries 9ndash11) It is worthmentioning that 6-amino-13-dimethyluracil when treatedwith formic acid under the current condition gave NN-diformylation product in lower yield (26 9 h)The reactionswere found to be clean and no side products were formed

To test the recyclability (vide Scheme 2) of nano-Al2O3

it was separated from the reaction mixture by adding ethylacetate (10mL) centrifuged at 3000 rpm to pellet out thecatalystThe separated particleswerewashedwith hot ethanol(3 times 10mL) to remove the organic impurities decanted driedin an oven at 80∘C for 6 h and reused for further reactionsThe efficiency of the catalyst was found to be unaffected up to4th run and after that its action started to decrease as shownin Table 3 The TONs were also retained from fresh up to the5th cycle and after that it decreased considerably

The recovered catalyst was also investigated throughpowder XRD and it was compared with the fresh nano-Al

2O3

(Figure 1) In the powder XRD of the recovered catalyst after6th run (Figure 1) the intensity of the peaks (4 0 0) and (1 0 0)weakened and became broad It might be due to the blockageof the pores of the catalyst which caused a decrease in effectiveactive sites and also due to the dislocation of the crystal planesafter each run which in turn decreased the yield

The SEMmicrograph of the fresh nano-Al2O3previously

reported by us [39] was also compared with the recycled one

Figure 2 SEM image of recovered nano-Al2O3after 4th run

(Figure 2) under the present study As indicated in Figure 2the recycled nano-Al

2O3revealed the aggregation of the

particles responsible for reducing its surface area and hencedeactivated the catalyst after 4th run which caused the loweryield of product

4 Conclusions

In conclusion we have demonstrated a novel method forsynthesis the NN-diformylation of bisuracil derivatives ingood yield under solvent-free reaction condition at 40∘C cat-alyzed by recyclable nano-Al

2O3rods Nano-Al

2O3catalyzed

organic transformations are less explored We believe thatthis work would find wide applications for new chemicaltransformations including those which enable the synthesisof complex natural products and derivatives

Conflict of Interests

The authors declare no financial conflict of interests

Acknowledgments

Vijay K Das thanks UGC for a Rajiv Gandhi NationalFellowship given to him The authors would also like toacknowledge Mr Prakash Kurmi Department of PhysicsTezpur University for carrying out XRD studies and fruitfuldiscussions

References

[1] D Astruc F Lu and J R Aranzaes ldquoNanoparticles as recyclablecatalysts the frontier between homogeneous and heteroge-neous catalysisrdquo Angewandte ChemiemdashInternational Editionvol 44 no 48 pp 7852ndash7872 2005

[2] J Grunes J Zhu and G A Somorjai ldquoCatalysis andnanosciencerdquo Chemical Communications vol 9 no 18 pp2257ndash2260 2003

[3] J Rautio P Peramaki J Honkamo and H Jantunen ldquoEffect ofsynthesis method variables on particle size in the preparationof homogeneous doped nano ZnO materialrdquo MicrochemicalJournal vol 91 no 2 pp 272ndash276 2009


[4] M T Reetz and E Westermann ldquoPhosphane-free palladium-catalyzed coupling reactions the decisive role of Pd nanoparti-clesrdquo Angewandte ChemiemdashInternational Edition vol 39 no 1pp 165ndash168 2000

[5] C Ramarao S V Ley S C Smith I M Shirley and NDeAlmeida ldquoEncapsulation of palladium in polyurea micro-capsulesrdquo Chemical Communications no 10 pp 1132ndash11332002

[6] J A Gladysz ldquoRecoverable catalysts Ultimate goals criteria ofevaluation and the green chemistry interfacerdquoPure andAppliedChemistry vol 73 no 8 pp 1319ndash1324 2001

[7] J A Gladysz ldquoIntroduction recoverable catalysts andreagentsmdashperspective and prospectiverdquo Chemical Reviews vol102 no 10 pp 3215ndash3216 2002

[8] G Pacchioni ldquoQuantum chemistry of oxide surfaces from COchemisorption to the identification of the structure and natureof point defects on MgOrdquo Surface Review and Letters vol 7 no3 pp 277ndash306 2000

[9] D M Cox D J Trevor R L Whetten and A Kaldor ldquoAlu-minum clusters ionization thresholds and reactivity towarddeuterium water oxygen methanol methane and carbonmonoxiderdquo Journal of Physical Chemistry vol 92 no 2 pp 421ndash429 1988

[10] V Polshettiwar and R S Varma ldquoGreen chemistry by nano-catalysisrdquo Green Chemistry vol 12 no 5 pp 743ndash754 2010

[11] V Polshettiwar B Baruwati and R S Varma ldquoSelf-assembly ofmetal oxides into three-dimensional nanostructures synthesisand application in catalysisrdquo ACS Nano vol 3 no 3 pp 728ndash736 2009

[12] V Polshettiwar M N Nadagouda and R S Varma ldquoThesynthesis and applications of a micro-pine-structured nanocat-alystrdquo Chemical Communications no 47 pp 6318ndash6320 2008

[13] A Fihri R Sougrat R B Rakhi et al ldquoNanoroses of nickeloxides synthesis electron tomography study and applicationin CO oxidation and energy storagerdquo ChemSusChem vol 5 no7 pp 1241ndash1248 2012

[14] K Shimizu R Sato and A Satsuma ldquoDirect CndashC cross-coupling of secondary and primary alcohols catalyzed bya 120574-alumina-supported silver subnanoclusterrdquo AngewandteChemiemdashInternational Edition vol 48 no 22 pp 3982ndash39862009

[15] A Murugadoss P Goswami A Paul and A ChattopadhyayldquolsquoGreenrsquo chitosan bound silver nanoparticles for selective CndashCbond formation via in situ iodination of phenolsrdquo Journal ofMolecular Catalysis A vol 304 no 1-2 pp 153ndash158 2009

[16] C AWithamW Huang C Tsung J N Kuhn G A Somorjaiand F D Toste ldquoConverting homogeneous to heterogeneous inelectrophilic catalysis usingmonodispersemetal nanoparticlesrdquoNature Chemistry vol 2 no 1 pp 36ndash41 2010

[17] P T Anastas and J C Warner Green Chemistry Theory andPractice Oxford Publication New York NY USA 1998

[18] M A P Martins C P Frizzo D N Moreira L Buriol andP Machado ldquoSolvent-free heterocyclic synthesisrdquo ChemicalReviews vol 109 no 9 pp 4140ndash4182 2009

[19] P J Walsh H Li and C A de Parrodi ldquoA green chemistryapproach to asymmetric catalysis solvent-free and highly con-centrated reactionsrdquoChemical Reviews vol 107 no 6 pp 2503ndash2545 2007

[20] K Tanaka and F Toda ldquoSolvent-free organic synthesisrdquo Chem-ical Reviews vol 100 no 3 pp 1025ndash1074 2000

[21] G Nagendrappa ldquoOrganic synthesis under solvent-free con-dition an environmentally benign proceduremdashIIrdquo Resonancevol 7 no 10 pp 59ndash68 2002

[22] K Tanaka Solvent-Free Organic Synthesis Wiley-VCH Wein-heim Germany 2009

[23] M Fathalla C M Lawrence N Zhang J L Sessler andJ Jayawickramarajah ldquoBase-pairing mediated non-covalentpolymersrdquo Chemical Society Reviews vol 38 no 6 pp 1608ndash1620 2009

[24] S Sivakova and S J Rowan ldquoNucleobases as supramolecularmotifsrdquo Chemical Society Reviews vol 34 no 1 pp 9ndash21 2005

[25] M W Powner B Gerland and J D Sutherland ldquoSynthesis ofactivated pyrimidine ribonucleotides in prebiotically plausibleconditionsrdquo Nature vol 459 no 7244 pp 239ndash242 2009

[26] O S Pedersen and E B Pedersen ldquoNon-nucleoside reversetranscriptase inhibitors the NNRTI boomrdquoAntiviral Chemistryand Chemotherapy vol 10 no 6 pp 285ndash314 1999

[27] A R Dinner G M Blackburn and M Karplus ldquoUracil-DNAglycosylase acts by substrate autocatalysisrdquo Nature vol 413 no6857 pp 752ndash755 2001

[28] F C Tucci Y F Zhu Z Guo et al ldquo3-(2-aminoalkyl)-1-(26-difluorobenzyl)-5-(2-fluoro-3-methoxyphenyl)-6-methyluracils as orally bioavailable antagonists of the humangonadotropin releasing hormone receptorrdquo Journal ofMedicinalChemistry vol 47 no 14 pp 3483ndash3486 2004

[29] D P Sutherlin D Sampath M Berry et al ldquoDiscoveryof (thienopyrimidin-2-yl)aminopyrimidines as potent selec-tive and orally available Pan-PI3-kinase and dual Pan-PI3-kinasemTOR inhibitors for the treatment of cancerrdquo Journal ofMedicinal Chemistry vol 53 no 3 pp 1086ndash1097 2010

[30] S Manta E Tsoukala N Tzioumaki C Kiritsis J Balzariniand D Komiotis ldquoSynthesis of 46-dideoxy-3-fluoro-2-keto-120573-d-glucopyranosyl analogues of 5-fluorouracil N6-benzoyladenine uracil thymine N4-benzoyl cytosine and evaluationof their antitumor activitiesrdquo Bioorganic Chemistry vol 38 no2 pp 48ndash55 2010

[31] T Lundqvist S L Fisher G Kern et al ldquoExploitation ofstructural and regulatory diversity in glutamate racemasesrdquoNature vol 447 no 7146 pp 817ndash822 2007

[32] J B Parker M A Bianchet D J Krosky J I Friedman L MAmzel and J T Stivers ldquoEnzymatic capture of an extrahelicalthymine in the search for uracil in DNArdquo Nature vol 449 no7161 pp 433ndash437 2007

[33] A Okamoto ldquoChemical approach toward efficient DNAmethy-lation analysisrdquo Organic and Biomolecular Chemistry vol 7 no1 pp 21ndash26 2009

[34] A Samanta D D Leonidas S Dasgupta T Pathak S EZographos and N G Oikonomakos ldquoMorpholino piperidinoand pyrrolidino derivatives of pyrimidine nucleosides asinhibitors of ribonuclease A synthesis biochemical and crys-tallographic evaluationrdquo Journal ofMedicinal Chemistry vol 52no 4 pp 932ndash942 2009

[35] R Rico-Gomez J M Lopez-Romero J Hierrezuelo J BreaM I Loza and M Perez-Gonzalez ldquoSynthesis of new man-nosyl galactosyl and glucosyl theophylline nucleosides withpotential activity as antagonists of adenosine receptors DEMA-induced cyclization of glycosylideneiminouracilsrdquo Carbohy-drate Research vol 343 no 5 pp 855ndash864 2008

[36] S Das and A J Thakur ldquoA clean highly efficient and one-pot green synthesis of arylalkylheteroaryl-substituted bis(6-amino-13-dimethyluracil-5-yl)methanes in waterrdquo EuropeanJournal of Organic Chemistry no 12 pp 2301ndash2308 2011


[37] J W Blunt B R Copp W P Hu M H G Munro P TNorthcotec and M R Prinsepd ldquoMarine natural productsrdquoNatural Product Reports vol 26 no 1 pp 170ndash224 2008

[38] V E Semenov V D Akamsin V S Reznik et al ldquoNewtype of pyrimidinophanes with 120572120596-bis(uracil-1-yl)alkane andbis(uracil-5-yl)methane unitsrdquo Mendeleev Communicationsvol 11 no 3 pp 96ndash97 2001

[39] V K Das R R Devi P K Raul and A J Thakur ldquoNano rod-shaped and reusable basic Al

2O3catalyst for N-formylation of

amines under solvent-free conditions a novel practical andconvenient rsquoNOSErsquo approachrdquo Green Chemistry vol 14 no 3pp 847ndash854 2012

[40] V K Das R R Devi and A J Thakur ldquoRecyclable highlyefficient and low cost nano-MgO for amide synthesis underSFRC a convenient and greener ldquoNOSErdquo approachrdquo AppliedCatalysis A vol 456 pp 118ndash125 2013

[41] V K Das M Borah and A J Thakur ldquoPiper-betle-shapednano-S-catalyzed synthesis of 1-amidoalkyl-2-naphthols undersolvent-free reaction condition a greener nanoparticle-catalyzed organic synthesis enhancement approachrdquo Journal ofOrganic Chemistry vol 78 no 7 pp 3361ndash3366 2013

[42] M Shojaie-Bahaabad and E Taheri-Nassaj ldquoEconomical syn-thesis of nano alumina powder using an aqueous sol-gelmethodrdquoMaterials Letters vol 62 no 19 pp 3364ndash3366 2008

[43] C Huang J Wang and C Huang ldquoSintering behavior andmicrowave dielectric properties of nano alpha-aluminardquoMate-rials Letters vol 59 no 28 pp 3746ndash3749 2005

[44] Y Zhang J Liu R He Q Zhang X Zhang and J ZhuldquoSynthesis of alumina nanotubes using carbon nanotubes astemplatesrdquo Chemical Physics Letters vol 360 no 5-6 pp 579ndash584 2002

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Analytical ChemistryInternational Journal of


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Organic Chemistry International


CatalystsJournal of

ElectrochemistryInternational Journal of



N

N N

N

O

RO

O O

N

N N

N

O

RO

O OH2N

NH2

HCOOH

Nano-Al2O3 Isolatedand

reused

OHCHN

NHCHO

Me

Me Me Me Me

MeMeMe40

∘C SFRC

2(andashk)1(andashk)

Scheme 1 NN-diformylation of bisuracil derivatives 1(andashk)

N

N N

N

OO O

O

N

N N

N

OO O

O

HCOOH

OHCHN

NHCHO

MeMe

Me

MeMe

Me Me Me

Catalyst

NH2

H2N

1a 2b

Scheme 2 Optimization of reaction condition

255 nm 119878BET = 18563m2 gminus1 120588 = 398 g cmminus3 and purityis 9999) were purchased from Sigma Aldrich and used asreceived The chemicals and reagents were purchased fromSigma-Aldrich Merck MS SD Fine Chemicals Pvt Ltdand Loba Chemie and used without further purificationTheXRD pattern was recorded with Rigaku X-ray diffractometerMelting points were determined in a Buchi 504 apparatus IRspectra were recorded as KBr pallets in a Nicolet (Impact 410)FT-IR spectrophotometer 1H and 13C NMR spectra wererecorded in a 400MHz NMR spectrophotometer (JEOLJNM ECS) using tetramethylsilane (TMS) as the internalstandard and coupling constants are expressed in HertzElemental analyses were carried out in a Perkin-Elmer CHNanalyser (2400 series II) Mass spectra were recorded with aWaters Q-TOF Premier and an Acquity UPLC spectrometerVisualization was accomplished with UV lamp or I

2stain

Reactions were monitored by thin-layer chromatographyusing aluminium sheets with silica gel 60 F

254(Merck)

22 General Procedure for NN-Diformylation of BisuracilDerivatives In a two-neck round bottom flask (50mL)nanorod-shaped basic Al

2O3(70mol 712mg) were taken

and then 1g (10mmol 414mg) and formic acid (9860mmol 023mL) were added After that it was allowedto stir on a pre heated oil bath at 40∘C for the requiredtime (the progress of the reaction was judged by TLC) Thereaction mixture was brought to room temperature after itscompletion and ethyl acetate (3 times 10mL) was added and thencentrifuged (3000 rpm) to recover the nanocatalyst Havingdone this the reaction mixture was washed with water andbrine dried over anhydrous Na

2SO4 and concentrated in a

rotary evaporator and finally the crude product was purifiedby column chromatography (30 ethyl acetate hexane as aneluent) The recovered catalyst was washed with hot ethanol(3 times 10mL) to remove the organic impurities decanted driedin an oven at 80∘C for 6 h and reused for evaluating theperformance in the next run in the reaction as shown inScheme 2

3 Results and Discussion

With the previously reported catalyst characterizations inhand [39] to begin with reaction of 661015840-diamino-111015840331015840-tetramethyl-551015840-(benzylidene)bis[pyrimidine-24 (1H 3H)-dione] [36] (1a 1 mmol) with formic acid (6mmol) waschosen as the model reaction (Scheme 2)

The optimization of the various parameters of this reac-tion is elaborated in Table 1 Initially the reaction wascarried out without using catalyst under solvent-free reactioncondition at 40∘C and 80∘C which did not yield any product(Table 1 entries 1 and 2) Various solvents were also testedunder the mentioned condition but they all failed (Table 1entries 3ndash11) to provide any product These negative resultssuggested that we look for an effective catalyst in the presentstudy Next various Lewis acid-base catalysts (Table 1 entries12ndash14) along with the nanocatalysts (Table 1 entries 15ndash18) were surveyed to observe the influence on rate andyield of NN-diformylation of 1a which were not fruitfulInterestingly nanorod-shaped basic Al

2O3stood out as a

choice of catalyst at 7mol loading (Table 1 entry 15) undersolvent-free reaction condition at 40∘C During the courseof our experiment we observed that at higher temperature
































240220200180160140120100

80604020

010 20 30 40 50 60 70 80 90

Inte

nsity

(cou

nts)

2120579 (scale)

100

400

6th reused

5th reused

4th reused

3rd reused

Fresh nano-Al2O3


recovered ones






2O3








4 Conclusions


2O3rods Nano-Al

2O3catalyzed




Acknowledgments


References


























































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry




CatalystsJournal of


































240220200180160140120100

80604020

010 20 30 40 50 60 70 80 90

Inte

nsity

(cou

nts)

2120579 (scale)

100

400

6th reused

5th reused

4th reused

3rd reused

Fresh nano-Al2O3


recovered ones






2O3








4 Conclusions


2O3rods Nano-Al

2O3catalyzed




Acknowledgments


References


























































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry




CatalystsJournal of

























































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry




CatalystsJournal of



Nanorod-Shaped Basic Al2O3 Catalyzed N,N-Diformylation of ...downloads.hindawi.com › journals ›...

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