Synthesis of a novel polyester building block from pentoses by tin-containing silicates PDF
Preview Synthesis of a novel polyester building block from pentoses by tin-containing silicates
RSC Advances PAPER View Article Online View Journal | View Issue Synthesis of a novel polyester building block from ce. pentoses by tin-containing silicates† n M. Lice Citethis:RSCAdv.,2017,7,985 4:42 Aported San. Gd.EE.lTlioaat,rancinCg.*Aandersen,b S. Tolborg,ac S. Meier,c I. Sa´daba,a A. E. Daugaardb 2n 2:U 023 1n 3.0 Wereportherethedirectformationofthenewchemicalproducttrans-2,5-dihydroxy-3-pentenoicacid d on 3/4/2Attributio umalskeinatlhgi-yfSlrnee-esBtceeortanfdraoistmiothnepsecinnattmoalseyetssht.auUnsoninldgaetrttoienpm-tcipmoenirstaeatduinricenosgnindsiitltihicoeantrsea,snagayesie1cl4da0toa–fly138st30s%.(cid:1)CTish.aeTchhpeireohvdiegudhc.etPstuisyriifiefoeldrdmstaerradensfuo-n2ud,n5ed-r wnloademmons dhiyhdyrdorxoyxhye-x3a-npoeantteenuosicingacCidandmideathyalnteasrtcetircawalipsasueseBd afosrthceo-cpaotlaylmyset.risTahtieoncos-tupdoileyms ewriistahtioenthyyliel6d-s y 2017. DoCreative Co RADceOccIee:pi1vt0ee.dd10123289tth/hcN6Noroavv2ee6mm7b0be8erdr22001166 aeinsvpteersrotdiignuactttehdecoupnsotianlyigneisnttregiflrufubonarccoktaibocoenntaiecl.gaTrnohhueypdsrreiodaceritgiavinintaydtionthgfiotfhlr–oeeminnectrocarnhpseo-mr2ai,ts5et-rddy,ihotylhedufirsnoxialylun-3sdt-rphaetyindntrgeonxthoyleicmpaoocitieedtniemtisaelwthfoaysrl ara www.rsc.org/advances functionalisingthenewco-polymers. 4 Januunder n 0ed Introduction indicating that it may be developed as a useful material in the ed ocens packaging materials segment.6 Ethylene glycol itself can be Publishcle is li Tbeheenempaerrtgiceunlcaerloyfsbuiocc-beasssfeudlcihnetmheicaalreparoodfupcotslyfersotmersmugaatersrihalass. pofrosdourbceitdolininvayriieoldusswofayuspfotori3n7s%tan1c4eobrydciraetcatllyyticfrohmydrgolguecnoasetioinn Article. This arti Sanimdpdleiaplocolyheostlse,rbsuucilhdinagsbllaocctkicsianccidlu,dseuhcycdinroicxyaacciiddsa,nddiac1i,d3s- cyioemldbsinoaft3io5n–7w5i%th.1r5,e16trIon-aalddoilffceor-ecnattaclyastatslystuicchapapsrtouancghstuesninsagltasciind ss propyleneglycol.Thesebuildingblockscanbeproducedfrom catalysis,sorbitolcanbedehydratedtogiveisosorbide.Thisdiol e Acc sugars by fermentation or chemocatalysis.1–3 While fermenta- has been successfully polymerised with different dicarboxylic en tion has been the preferred method, research aimed at trans- acidsresultinginnewtypesofpolyestermaterials,someofwhich p O forming sugars into polyester building blocks using chemo- have already become commercial products.6,7 Adipic acid is catalytic processing has proliferated during the last decade.4–9 accessiblefromglucoseintwostepsbycatalytichydrogenationof These activities are driven partly by the prospect of chemo- glucaricacid.17Racemicmethyllactatecanbemadedirectlyfrom catalysis offering cost advantages over fermentation, but also C6 sugars in yields up to 75% using tin-containing silicates as bytheprospectofgainingaccesstochemicalproductsthatare catalysts.18Lacticacidisanestablishedpolyesterbuildingblock inaccessiblebyfermentation.Polyesterbuildingblocksthatare used in the production of poly(lactic acid) which has become accessible in few steps from sugars using chemo-catalysis widely used as a bio-based polyester material within the pack- include 2,5-furandicarboxylic acid, ethylene glycol, adipic agingmaterialssegment.19Thenewestandleastknownmember acid,isosorbide,lacticacidand2-hydroxy-3-butenoicacid. ofthisgroupismethylvinylglycolate(MVG),whichcanbemade 2,5-Furandicarboxylic acid is accessible via acid catalysed directly from C6 sugars in yields up to 20% as a co-product to dehydrationoffructose,followedbyoxidation.10–12When2,5-fur- methyllactateandfromC4sugarsinyieldsupto60%.8,20–22Dueto andicarboxylic acid is polymerised with ethylene glycol, poly- itschemicalsimilaritytolacticacid,MVGcanbeco-polymerised ethylenefuranoateisformed.13Thispolyesterhasbeenshownto with lactic acid to produce a co-polyester having pendant vinyl have favourable barrier properties compared to PET plastics, groupsthatallowforpostfunctionalisation.23Here,wereportthat pentose sugars can be converted into a new activated polyester buildingblock,trans-2,5-dihydroxy-3-pentenoicacidmethylester aHaldorTopsøeA/S,HaldorTopsøesAll´e1,2800-Kgs.Lyngby,Denmark.E-mail:esta@ (DPM),inonestepusingtin-containingsilicatesascatalysts.We topsoe.dk havefurthermoreisolatedgramquantitiesofDPMandweshow bDanish Polymer Centre, Department of Chemical and Biochemical Engineering TechnicalUniversityofDenmark,Sølvtosplads,2800-KgsLyngby,Denmark the successful co-polymerisation of DPM and ethyl 6-hydrox- cDepartmentofChemistry,TechnicalUniversityofDenmark,Kemitorvet,2800-Kgs. yhexanoate (E6-HH) using enzymatic polymerisation. The co- Lyngby,Denmark polymers can be functionalised by thiolation or acetylation of †Electronic supplementary information (ESI) available. See DOI: theolenandhydroxylmoiety,respectively. 10.1039/c6ra26708d Thisjournalis©TheRoyalSocietyofChemistry2017 RSCAdv.,2017,7,985–996 | 985 View Article Online RSCAdvances Paper The catalytic conversion of sugars to lactic acid derivatives most studied tin-containing silicate is Sn-Beta, inwhich tin is using tin-containing silicates has been reported for all simple incorporated into a framework of silica having the *BEA monosaccharides.20,21,24,25 The rst report was related to triose topology.Sn-Betaisoenreportedasbeingasuperiorcatalyst sugars in water and methanol and later reports described compared to other tin-containing silicates for these reac- similarchemistryoccurringforhexoses,tetrosesandpentoses. tions.18,30,31,37,38Currently,thissupposedsuperiorityofSn-Betais The product selectivity varies, depending on the length of the not well understood, especially under operando conditions. sugarmolecule.Triosesformexclusivelylactateswhiletetroses Recent work aimed at elucidating the catalytic functioning of leadtohighyieldsofMVG.Pentosesandhexosesformmultiple Sn-BetaincludesDFTcalculations,FT-IR,TPRand119Sn-NMR e. products,dependingamongstotherfactorsonthepresenceof spectroscopy.39–44 Despite it being a crystalline material, the nc co-solutesinthereactionmedium.Recentlywehaveshownthat preparation method oen greatly inuences the catalytic M. Lice trans-2,5,6-trihydroxy-3-hexenoic acid methyl ester (THM) is performance. Two principally different preparation methods 4:42 Aported sfoilrimcaetedsinasyicealdtaslyosfts15a–n1d8%infrthome ahbesxeonsceesoufsiandgdteidn-ccoon-stoaliuntiensg. acorendnitoiornmsaullsyinugshedyd,rodirueocrticsaycnitdheassismiunnedraelrisihnygdarogethnetr[mSnal- 2n 023 12:n 3.0 U Twhaesidreeancttiioendapsatthhweainytewrmasedeilautceidreastepdonasnibdle3f-odretohxeygfolurmcoastoionne BBeettaa (zHeoTl)i]teanwdithsyantthinessisoubrycepo[Ssnt-tBreeatatm(PeTn)t].oTfhaedSenal-uBmetain(aHteTd) d on 3/4/2Attributio ofufrftWuhriesalhpderreoerdicvuoactntivtaiennsu.d2e6oofurreelaxtpeldoralatciotonnoefscahnedm5o--hcaytdarloyxtiycmseutghayrl fitseypwdiicdffiaelcflyeuclcttost.noTsiinisnctsoloropafdolrianartggesehuhipgyhdteorro2pl%ohaodabirniecgtcsyrpoyifscttaainlllsy.45oeSfmn3p-–Bl5oeytmeamd(P,wTas)itiihst wnloademmons ppraottceersnsinemg,etragkeisngbatsheedseornepthoretspriniotrorceopnosritdsercaotniosnis.tiAngproofdtuhcet mumadineatferdo.mThaepSanr-eBnettaA(lP-BTe)tcaryzsetaollitseizewihsicihnhheraistedbefernomdethale- DoCo homologous series of a-hydroxy esters: THM from hexoses, parentmaterialandisoenintherangeof0.2–1mmindiam- 017. ative MVG from tetroses and methyl lactate from trioses. From this eter.Thematerialcontainsmanydefects,causingittobemore y 2Cre trend, a similar C5 product can be predicted for pentoses hydrophilicthantheSn-Beta(HT).Severaldifferentmethodsof n 04 Januared under a (prSeacctheibnelmtelyeeids1t)ee.nrTtihveiesrdspioarmondouoncfgt,ttrDraiPhnsMy-d2,r,o5is-xdytiphheeyndatracontxiovyia-c3te-apdceinadnteddneorbiiivcoactaoivcmeids- ieenmxccophrlaopnyogereda4t7isnaugncdhtiranesuivnxatpoinoutihsr-oepphrdaoespaeylludamelpcionohsaitotelidowni,zt4he6oasliottleiindassraetlat.t4be8eiionng d oens formedfromxyloseinwater.29Here,weverifythatthisproduct, We synthesised Sn-Beta (HT) and Sn-Beta (PT) with a tin Publishecle is lic DxyPloMse,,islyixnodseeeadnfdorrmibeodsei.nTyhieisldsnodfiunpgstoho3w3%sthfraotmtinth-ceopnetnaitnoisnegs caonndteonttheorf 1L.e2w5i–s1.a5c%idiacloBnegtsaidzeeooltihteesr.tiTnh-ceosentaminaitnergiaslislicwaeteres Article. This arti sdielihcyadterastidoinssploafysaugraermsatorkaaffbloerdabiniltietyrmtoedciaartyalbys,ge-ucnosnasteucruattievde ttehseteadiminofthideepnrtoifdyuinctgioanctiovfitDyPpMattferronmsaxnyldosoeptiinmmiseinthgatnhoelDwPitMh s a-keto-aldehydeswhichareconvertedintotheb,g-unsaturated yield. s ce a-hydroxyesterendproducts(Scheme1). c A n Tin-containing silicates are solid Lewis acid materials that Experimental e p are capable of activating carbonyl groups in small molecules O andcatalysesimpletransformations.ExamplesincludeBaeyer– Catalystsynthesis Villiger oxidation, Meerwein–Ponndorf–Verley–Oppenauer Sn-,Zr-,Ti-andAl-Beta(Si/M¼150)viahydrothermalsynthesis redox reactions, monosaccharide isomerisation, aldol- and were prepared by modifying the route described by Valencia retro-aldolreactionsandcertaindehydrationreactions.30–36The etal.45,49InatypicalSn-Beta(Si/Sn¼150)synthesisprocedure, 30.6 g of tetraethyl orthosilicate (Aldrich, 98%) was added to 33.1 g of tetraethylammonium hydroxide (Sigma-Aldrich, 35% inwater)undercarefulstirring((cid:3)60min),andtin(IV)chloride pentahydrate(Aldrich,98%)dissolvedin2.0mLofdemineral- isedwaterwasaddeddropwise.Themixturewasthenletostir for several hours. Finally, 3.1 g hydrouoric acid (Fluka, 47– 51%) in 1.6 g of demineralised water was added. All samples werethenhomogenisedandtransferredtoaTeon®-container placed in a stainless steel autoclave. The samples were then incubated at 140 (cid:1)C for 14 days. The solid was recovered by ltration and washed with demineralised water, followed by dryingovernightat80(cid:1)Cinair.Theorganictemplatecontained withinthematerialwasremovedbyheatingthesampleat2(cid:1)C min(cid:4)1to550(cid:1)Cinstaticairandmaintainingthistemperature for6h. Zr-Beta(Si/Zr¼150)andAl-Beta(Si/Al¼150)zeoliteswere Scheme1 Formationofhomologousa-hydroxyesterproductsfrom C –C sugars catalysed by tin-containing silicates. The reaction is preparedbytheaforementionedprocedure,exchangingthetin 3 6 applicablebothtoaldosesandketoses. sourcewithzirconylchlorideoctahydrate(Sigma-Aldrich,98%) 986 | RSCAdv.,2017,7,985–996 Thisjournalis©TheRoyalSocietyofChemistry2017 View Article Online Paper RSCAdvances or aluminium chloride hexahydrate (Fluka, $99%), respec- in60gofdemineralisedwater.Thesolutionwasthenstirredfor tively. Furthermore, Al-Beta was incubated for only 5 days at 2 h. To the synthesis mixture 18.0 g of tetraethyl orthosilicate 140 (cid:1)C. For Ti-Beta (Si/Ti ¼ 150), tetraethyl orthotitanate (98%,Aldrich) wasaddedfollowed bytin(IV)chloridepentahy- (Aldrich)wasrstdissolvedinamixtureofhydrogenperoxide drate(Aldrich,98%)dissolvedin2.0gofdemineralisedwater. and water and then used in a similar fashion as the metal Themixturewasthenstirredfor24hat40(cid:1)Candthentrans- source.SnO -Beta(Si/Sn¼200)wassynthesisedusingtinoxide ferred to a Teon®-lined autoclave and heated to 100 (cid:1)C for 2 (Aldrich, <100 nm) as the tin source. Purely siliceous Beta (Si- 24h.Thesolidwasrecoveredbyltration,washedwithample Beta)waspreparedbyomittingtheadditionofametalsource. waterandthencalcinedat550(cid:1)Cfor6hours. e. Sn-Beta (Si/Sn ¼ 125) via post-treatment was prepared nc according to a modication of the procedure described by Catalystcharacterisation 4:42 AM. ported Lice Hu12ma.m5in,maNtoeHnd4d+b-fyeotrtmrael).a4t7wmCaesonmtcamwlcietirhncei1ad0l azgteoo5lf5it0ceo(cid:1)nBCceetanfot(rrZae6teodlhysntai,ntrSdiic/Adaelcai¼dl- sCoartpatliyosnt acnhdarIaCctPe-rOisEaSt.ioPnowwdaesrXp-erarfyodrmifferdactbioynX(RXDRD, )BpEaTt,terNn2s- 2n of the prepared and calcined samples were measured on an 023 12:n 3.0 U (aStig8m0a(cid:1)-CA.ldTrihceh,s$ol6id5%w)apserregcroavmeroefdzeboyliteltBraettiaopno,wwdaesrhfeodr1a2nhd aXr'Peaertanddiffpraocrteomvoeltuemr (ePhmileiapssu)ruesminegntCsuw-Kearerapderiafotiromne.dSuursfaincge Downloaded on 3/4/2Commons Attributio A5dircmaarlgdtlipicerooidrinfceoheagtfhdtn,e1a19(2t1s58e5o05%d.l0i(cid:1))FdCb(cid:1)o.wyCrAfaoitsfrnhoecd1irrsi2ipts6hpisheeouhnalr)ivt.pnmeodTwdpsherceieeta,nngltdcneiwiensanaas(teItliIeudom)rmncae(hgpit5nhlar.o7aoiorn5tcdie.deodmselsoLz,(ge0)tyoh.1alewni2ts8dieathgmwa,dapaSdslieeSgtdihmw/Seatannos- mwtsmauaiuernsnflaettcidcspae)lou.cisuaTnirlnhtaegeNtaet2tdhaoaentbdadBysloEtsrpThupoemrtrifetoae-ncptseh/lidoozateedrsmeoaaanrenptd(ahtSiltoBoyhsEdneeT)roumnsoi(icQfnarngutohapAtenhoutrestaeoacAsvmhuoorprtlouoblmesmasoeuerwbt(oIV3anmsmssatioocrtrubioc)--- 017. ative Sn-MFI (Si/Sn ¼ 100) was prepared following a procedure wS3araen.dThTeabchlearSa1c.t†erTihsaetieolnemreesnutlatlscaoremsphooswitnioinnothfethEeSIp,rFeipga.rSe2d, y 2Cre described by Mal et al.50 In a typical synthesis, tin(IV) chloride materials was measured using inductively coupled plasma- n 04 Januared under a paAlelidnsretiadchhwy)a.dtTreahrtieasn(mAdliadxdrtuidcrehed,wt9oa8s1%5t)h.6ewgnaossftditreirstersdaoelfvtoherdyl3io0nrmt5hiongs.iolAifcadeteremw(9ain8rd%esr-,, amtoomdeilcOepmtiimssaio3n00s0p(eVcatrrioasncoVpiysta()I.CP-OES) on a PerkinElmer d oens 13.4goftetrapropylammoniumhydroxide(40%,AppliChem)in Catalytictests ec s Article. Publish This article is li 11satrud63ab0.dn4ses(cid:1)egdfCqe.orufTfroeedhrndeet2mlsytdooinlaaueynatsriaoaTulndiensddewiodetanirswo®sntat-hataleieltnrinc6ew0dlceaosganausdodttifiodtricerdolideannmvasge.nifTndoahernsret2dai0rlsirossheyledi.nddTtfhohwwreeaas1stgiesherrele,dcawwonaaavdsst- I>1(Bn98i90o.at8ma%ggte)y,)op.3fiNc6ca0oaltmsapelgyexscp(ti2eaw.rl4iemprmreeemncatado,udl)te4ixod.y0nltososgweae(m5rSeiemgttmahLkaaegn-nlAoallstdosr(iamScvhiiogc,mird>oa9wm-9Aa%olvdie)srtaivucnihradel, ces eredbyltration,washedwithamplewateranddriedovernight or oxygen. The reaction vessel was heated under stirring (600 n Ac at80(cid:1)Cfollowedbycalcination(2(cid:1)Cmin(cid:4)1,550(cid:1)C,6hdwell rpm)for2hinaBiotageInitiator+microwavesynthesiser.Aer pe time)toobtainthenishedmaterial. cooling, samples were retrieved and analysed. In some experi- O Sn-MCM-41 (Si/Sn ¼ 200) was prepared according to the ments, an alkali salt co-solute was added by replacing the appropriate portion of the methanol solvent with a 1.0 mM methoddescribedbyLietal.51Inatypicalsynthesis,26.4gof tetraethylammonium silicate (Aldrich, 15–20 wt% in water, standard solution of potassium carbonate (Sigma-Aldrich, $99.99%) was slowly added to a solution of 13.0 g of hex- $99.0%)inmethanoltoobtainthedesiredconcentration. adecyltrimethylammonium bromide (Sigma, $99.0%) dis- Productanalysisforcatalysttesting solvedin38.0gofwaterandallowedtostirfor1h.Atthispoint, tin(IV) chloride pentahydrate (Aldrich, 98%) and hydrochloric Analysisofthereactionmixtureswasperformedusingacombi- acid(Sigma-Aldrich,min.37%)in2.1gofwaterwasaddeddrop nation of GC-FID, HPLC and 1D and 2D NMR. A Bruker wisetothesolutionandallowedtostirfor1.5h.Tothissolu- (F¨allanden,Switzerland)AvanceII800MHzspectrometerequip- tion,12.2goftetraethylorthosilicate(98%,Aldrich)wasadded ped with a TCI Z-gradient CryoProbe and an 18.7 T magnet and stirred for 3 h. The sample was then transferred to a Tef- (Oxford Magnet Technology, Oxford, U.K.) was used for the lon®-linedcontainerinastainlesssteelautoclaveandplacedin identication of unknown products. A 7890A Series GC system apre-heatedovenat140(cid:1)Cfor15h.Thesolidwasrecoveredby (AgilentTechnologies)with aPhenomenex ZebronZB-5column ltration, washed with ample water and dried overnight at and a FID detector was used for the quantication of glyco- 80 (cid:1)C. The material was nalised by calcination, heating the laldehydedimethylacetal(GA-DMA),methyllactate(ML),methyl sampleto550(cid:1)Cat2(cid:1)Cmin(cid:4)1instaticairandmaintainingthis vinyl glycolate (MVG), methyl 4-methoxy-2-hydroxybutanoate temperaturefor6h. (MMHB) and 2,5-dihydroxy-3-pentenoic acid methyl ester Sn-SBA-15(Si/Sn¼200)waspreparedfollowingthesynthesis (DPM).With theexception ofDPM, commercial standardswere route described by Ramaswamy et al.52 In a typical synthesis, used for the calibration. DPM was synthesised and puried as 1.0 g of hydrochloric acid (37 wt%, Fluka) in 140 g of demin- describedunder“Isolationoftrans-2,5-dihydroxy-3-pentenoicacid eralisedwaterwasaddedtoasolutionof8.0gofPluronic®P- methylester(DPM)”andthepurematerialwasusedincalibration 123 (PEG–PPG–PEG polymer, Aldrich, M ¼ (cid:3)5800 g mol(cid:4)1) standards. w Thisjournalis©TheRoyalSocietyofChemistry2017 RSCAdv.,2017,7,985–996 | 987 View Article Online RSCAdvances Paper AnAgilent1200seriesHPLCequippedwithanAminexHPX- a crude brown residue. trans-2,5-Dihydroxy-3-pentenoic acid 87H (BioRad) column (0.004 M H SO , 0.6 mL min(cid:4)1, 65 (cid:1)C) methylesterwasisolatedfromthecrudebydrycolumnvacuum 2 4 using a refractive index and diode array detector was used for chromatography using ethyl acetate/heptane as the eluent, detectionandquanticationoffurfural,furfuraldimethylacetal typically yielding 2.6 g trans-2,5-dihydroxy-3-pentenoic acid andotheranalogues.Theaqueousacidiceluenthydrolysesall methyl ester of >94% purity (GC-MS, Fig. S4,† 1H-NMR, furfural analogues back to furfural, resulting in a collective Fig.S5†). quanticationofallfuranics(FUR). trans-2,5-Dihydroxy-3-pentenoic acidmethyl ester.1HNMR One-dimensional 1H NMR spectra were used to quantify 3- (400 MHz, CD OD) d 5.89(dtd, J¼ 15.5, 5.0, 1.4Hz, 1H), 5.72 3 e. deoxy-g-pentonolactones (DPL), 2,4,5-trihydroxy-3-pentanoic (ddt,J¼15.5,5.7,1.7Hz,1H),4.76(s,4H),4.58(ddt,J¼5.7,1.4, nc acid methyl ester (TPM) and 2,5-dihydroxy-4-methoxy- 1.4Hz,1H),3.99(ddd,J¼5.0,1.6,1.4Hz,2H),3.63(s,3H),3.21 AM. d Lice pentanoic acid methyl ester (DMPM) using the CH3 signal at (p, J ¼ 3.3, 1.6 Hz, 1H). 13C NMR (101 MHz, CD3OD) d 173.2, 4:42 porte 1o.n39repapcmtiofnrommixMtuLreassainremfeertehnacneo.lSapecetrrarewmeorevarlecoofrcdaetdaldysirteacntldy 132.2,126.8,70.9,61.3,51.2. 2n 023 12:n 3.0 U uSppeocntraaddwietiroenroefco1r0d%ed(vo/vn)Da4-BmruetkhearnAolva(CnacembIIrIidsgpeecIstrootompeetse)r. Etrnaznysm-2a,5ti-cdiphoyldyrmoxeyri-3sa-ptieonnteonfoeitchaycli6d-hmydetrhoyxlyhesetxearntooatpeoalyn(Ed6- 2o d on 3/4/Attributi epfrqreouqtiuopenpnecdrieewssoitonhfana3c.e39s6.4pwTpemrme,ag4sn.u7ep8tp6raenpsdpsmead uBbsBiyOngpprtrehosbeaett.uwrMoateiltoohngaincaoatll HFoHr-ctoh-DePcMo)-polymerisation, 0.40 g (3 mmol) of trans-2,5- wnloademmons scahmanpnlienlsgo8f0t9h6ecsopmecptlreoxmdeattear.pSopinectstrdauwreinregraencoarcdqeudisaitti3o0n(cid:1)tCimbey detihhyyldr6o-hxyy-d3r-opxeynhteenxaonicoaatceid(Simgmetah-yAlldersitcehr,, 29.70%g) a(1n3dm0.m24olg) ooff DoCo of 1.02 seconds, employing an inter-scan delay of 10 seconds N435 (Novozymes) was added to a Schlenk tube. The mixture 017. ative andaccumulating16scans. 2w0a0smplbacaerdprinesasnuroeilfobra2thhu,nbdefeorrmebageninegticresdtuircreindgtoat56m0(cid:1)bCarafnodr ed on 04 January 2censed under a Cre astDipfPsyeMpTcmewtrcoaaetr-ttdhahilnyamlawdtegiudnlarytsachi1loo3sonC1if3adCle2cs12aiHrs(rpoM–ipe1toG3mrCp)oitcHaffonsSadseQbatCumreonpssfdipldae1enu0ctact1hrelea.psawupTnbmheosreemtra1auenHtsredie–cd1re3erCmteloagptiHqiolvouSneyaQentoCdof- a(Td$Snrhi9ooge9fmtu%hrael)a-tr.AnrRal7dte0aerfnrihcidwgh.ae,psTr$arheete9icvoi9apnp.p9irotao%artdta)e5utdeac(cid:1)dntCidnwifniaomcsrvoam3lddc0ieusdmosm,ioaielnrtvteeehf-lddyaonillsioonsllwtoelte(rveSdeetidrdgbamhybinyyad-lsAtrtueorldatcfruttraiiiroochahnnyn-,,. Publishcle is li xtiyvliotsye.Saanmdpiltessmweertehpylregplyacroesdidbeyscoantdheinghsinregs1olmutLioonftahnedlsteenresdi- y6i2e%ldeydiepldo)l.y(E6-HH-co-DPM)asanorangestickysolid(1.088g, ss Article. This arti rrseepadecicsttisrooanlvwimenrgiextrutehrceeorudrseeisdnugoltnaanaStpBerreuedskiVedarucAevvaaincnuceuDmII4I-mcHoeDnthcseapnnetocrlat.rtooTmrhaeetnseder 52.8668P5oH,ly1zm7,20e1.r1.6I1HH–)-,pN5oM.l7y9R(E(6d(3-dH0,0HJ¼M-coH1-5Dz.,4P8CM,D)4.C.5Fl83T)-HIdRz,5(0.c9.m177(cid:4)(Hd1))t,,34J4.96¼62,(1d25,9.J4493¼,, en Acce esaqmuipplpinedgw10it2h4aan9.d41T2m8caogmneptlaexnddaataBrpuokienrtsCirnyotPhreob1HeParnoddi1g3yC, 43..3979(Ht,zJ,¼0.168.6H4)H, 4z.,514.6(4dH, J),¼3.558.5(9t,HJ¼z,80..2236HH)z,,40..1178H(m),,20.2.347(Ht,)J, p spectral dimensions foracquisitiontimes of292 and 58milli- O ¼7.47Hz,2.00H),1.58(m,4.13H),1.31(m,2.11H),1.19(t,J¼ seconds, respectively. Spectra were processed with extensive 7.19Hz,0.06H).13C-NMR(75MHz,CDCl )d173.5,172.8,130.0, zerollinginalldimensionsandintegratedinTopspin3.5. 3 126.7,70.4,67.9,65.9,64.1,34.0,28.3,25.4,24.5. InsampleswhereDPMorMLwerepresentinlessthan10%, estimations of DPL, TPM, DMPM, MG and residual substrate were quantied by a combination of an Agilent 1200 series Triuoroaceticanhydrideestericationofpoly(E6-HH-co- DPM) HPLCequippedwithaCarbohydrate(Zorbax)column(60wt% acetonitrile/water, 0.5 mL min(cid:4)1, 30 (cid:1)C) and two-dimensional In a typical esterication, 63 mgpoly(E6-HH-co-DPM) wasdis- 1H–13CHSQCemployingstandardadditionofxylose.50mLof solved in 0.7 mL D-chloroform (Sigma-Aldrich, 99.8%) and a 100 mM stock solution in D -methanol was added to the transferredtoaNMRtubeand4dropsoftriuoroaceticanhy- 4 sample and spectra were re-recorded by the aforementioned dride (Sigma-Aldrich, >99%) were added. The mixture was two-dimensional1H–13CHSQCprocedure. precipitated in cold methanol (Sigma-Aldrich, $99%) and refrigeratedat5(cid:1)Cfor30min.Themixturewastransferredto a syringe and ltered using a Teon® syringe lter. The lter Isolationoftrans-2,5-dihydroxy-3-pentenoicacidmethylester waswashedwithchloroformandtheliquidwascollected.The Up-scaled reactions were performed in a 1 liter autoclave solvent was evaporated under ambient conditions and the (Autoclave Engineers) with mechanical stirring. The autoclave product was dried overnight in a vacuum oven at 30 mbar at wasloadedwith300gofmethanol,18gofxyloseand4.5gof room temperature, yielding the functionalised polyester (poly- Sn-Beta(PT)andheatedunderstirringto160(cid:1)Cfor16h.The mer II). Coupling yield was determined by 1H-NMR, based on autoclavewasallowedtocool,thecatalystwasthenremovedby thechangeinchemicalshioftheprotonsvicinaltothealcohol ltrationandthereactionmixturewasdriedovernightwith50g groupofDPM. molecular sieves. The molecular sieves were ltered from the Polymer II. FT-IR (cm(cid:4)1) 3500, 2960, 2864, 1723. 1H-NMR productmixtureandmethanolwasremovedinvacuoaffording (300 MHz, CDCl ) d 6.11 (dt, J ¼ 15.68, 5.39 Hz, 0.19H), 5.92 3 988 | RSCAdv.,2017,7,985–996 Thisjournalis©TheRoyalSocietyofChemistry2017 View Article Online Paper RSCAdvances (dd,J¼15.61,6.39Hz,0.18H),5.63(d,J¼6.37Hz,0.16H),4.67 evaporate in a closed vessel at room temperature to ensure (d,J¼5.23Hz,0.28H),4.21(m,0.38H),4.10(t,J¼6.56,1.70H), a slow evaporation of the solvent. The resulting lm was hot- 3.91(t,J¼6.63,0.11H),2.37(t,J¼7.49,2.00H),1.66(m,4.21H), pressedat70(cid:1)Cfor10mintoensureauniform,atlm. 1.39 (m, 2.32H), 1.26 (m, 0.14H). 13C-NMR (75 MHz, CDCl ) 3 d 175.8, 175.7, 166.6, 158.9, 149.7 (q), 131.5, 123.2, 113.7 (q), Watercontactanglemeasurements 74.8,68.01,67.9,66.6,65.1,34.3,28.2,25.5,24.6. A water droplet of 15 mL was placed on the surface with the needle inside the drop, and the drop was expanded and con- Thiol–enefunctionalisationofpoly(E6-HH-co-DPM) tractedonthesurfaceofthepolymerlmatarateof2.0mLs(cid:4)1. ce. For the thiol–ene functionalisation, 15 mg poly(E6-HH-co- All water contact angle measurements were determined as an AM. d Licen aDnPdM2),.94mdgro(p0s.0o2fmmmerocla)p2to,2a-cdeimticetahcoidxy(-2S-ipgmhean-Aylladcreictohp,h$e9n8o%ne) daviffereargeentopfosthitrioeensmoneatshuerepmoleynmtserosfurtfharceee. different drops at 4:42 porte (Sigma-Aldrich, 99%) was dissolved in 0.6 mL D-chloroform 2:2Un (Sigma-Aldrich,99.8%).ThemixturewastransferredtoaNMR Results and discussion 023 1n 3.0 tyuiebledinangdthirerathdiioatlefdunwcittihonUaVlisleidghpto(llye¼ste3r6(5ponlmym)efrorII3Ic0).mTihne, Identicationoftrans-2,5-dihydroxy-3-pentenoicacidmethyl 2o 3/4/buti conversion of the double bond was determined by 1H-NMR esterandco-products d on Attri from the signals at 5.97 and 5.79 ppm corresponding to the Thorough analyses of product mixtures from reactions using 7. Downloadeve Commons sfi3nuu4cnb6rc1settaiicotsumnetdai(cid:4)ol1ipns.raePotsiofoelnntyhmceeewdorasofsucIbIaIfrlaueb,rotbbhxoy,enlriddc caainocninddpoferlumynw(eEced6tri-eoHnbpHyarl-eictpody-aeDirtneePdcMFtiTb)o.-ynITRthhoaiestf xitanoydlidtothiisateeilolpyanrspeaevltirhpofeourorssmdluyuebrcdesttpsbroaywrtGteeerCdae-nMrpedrSter.SosHne-an-eBlrtdee.9ot,i2alt5a,w2(n6HadAsTndf)oaeaulhysnysddtishrtaehotfaicotatnhitnaeplayrpdsortddouiwdtciueotrcsnet, ary 201a Creati awfiothrem1-emnetirocnapedtohpreoxcaendeu,rme,eerxccahpatonegtihnagntohl,e2d-eertihvyalthiseixnagneatgheinotl cmoinxturrmeseduthsiengpre2seDnceheotferDoPnMuclaelaorngs(1iHde–133-Cd)eoxsyp-egc-tpreonstcoonpoy-, 4 Januunder oScrhtehmioep3h.enol respectively, and coupling yields are given in l(aTcPtMon)easnd(D2,P5L-d),ih2y,d4r,5o-xtyr-i4h-ymderothxyopxey-npteanntoaincoiaccaidcidmmeeththyylleesstteerr ed on 0censed Polymercharacterisation (pDoMrtePdM)f.orThtheesecopnrovderuscitosnaoref htheuxossehsomtoolTogHuMesaonfdth3o-dseeoxrey-- Article. PublishThis article is li NStseppMmeeccRptterrcaorhaswatpureiarnrece-tBeburruasisisknaeetgdriooCnAnDCoChfolp33mo0lao0ysmnuseMcorlslHevawezrnatas.snppdAeescrhsftoriegortnmemrmeoednteenurotcnsleaaaotrf7crTNooeMrosrmleRa- gaNfonlMuraclRoythsnsieospleapcccrottornoocvneseedcrsous.piroFeynowtlolaoosqfwueipnsatengantbtithfloyiissshtehsienedi(,tdSiciacffohlmeewrmbeonirenkti,nr2aeg).acGcoTtCimho,inpsHrpePahrLnoeCadnluasycinsvtidess ess lation spectroscopy (1H–1H COSY and 1H–13C HSQC spectra). procedure was used for comparing different catalysts, condi- c Ac Glass transition temperatures (T ) and melting temperatures tionsandco-solutesandforoptimisingtheyieldofDPM. n g e (T )wereobtainedusingaDiscoveryDSCfromTAInstruments. p m O Thermalanalyseswereperformedataheatingandcoolingrate Reactionpathwaysforpentoses of10(cid:1)Cmin(cid:4)1from(cid:4)100to150(cid:1)C.T andT weremeasured g m In the presence of Lewis acidic silicates, pentose sugars react attheinectionpointandatthepeaktemperature,respectively. along three primary reaction pathways leading to a variety of Fouriertransforminfrared(FT-IR)spectroscopywasconducted products (Scheme 2). These are grouped accordingly: (1) onanattenuatedtotalreection(ATR)-FT-IR(ThermoiS50with formation of methyl glycosides (MG) catalysed by Brønsted abuilt-indiamondATRwitharesolutionof4cm(cid:4)1)inorderto acidsintheabsenceofalkalico-solutes;(2)retro-aldolreactions conrm the presence of functional groups. Molecular weight leadingtoC –C a-hydroxyestersandglycolaldehydedimethy- 3 4 and polydispersities were determined using Size Exclusion lacetal which are catalysed by Lewis acidic silicates in the Chromatography(SEC).SECwasperformedinTHFonaVisco- presence of alkali co-solutes; (3) dehydration via 3-deoxy- tek GPCmax autosampler equipped with a Viscotek TriSEC xylosone (3-DX) to give DPM, DPL, TPM, DMPM and furfural model302tripledetectorarray(RIdetector,viscometerdetector derivatives(FandF-DMA),catalysedbytin-containingsilicates and light scattering detectors measuring at 90(cid:1) and 7(cid:1)) and intheabsenceofalkalico-solutes. aKnauerK-2501UVdetectorontwoPolymerLaboratoriesPLgel Thecentralintermediate3-DXcanbetransformedintoDPL MIXED-Dcolumns.Thesampleswererunataowrateof1mL via a 1,2-hydrideshiofits intramolecularhemiacetal. Xylose min(cid:4)1 at 35 (cid:1)C and molecular weights were determined from give rise to two different DPL diastereomers that can be dis- aPScalibration. cernedbyNMRspectroscopy.Wespeculatethesetobe3-deoxy- g-D-xylonolactone and 3-deoxy-g-D-lyxonolactone, formed by Filmcasting racemisation on C in the 1,2-hydride shi step. In an analo- 2 Inatypicalprocedure0.27gof3-polycaprolactone(Perstop,M gous open chain form, 3-DX can react with methanol to form n ¼ 50000 g mol(cid:4)1) and 0.030 g of poly(E6-HH-co-DPM) was ahemiacetalwhichcanundergoa1,2-hydrideshileadingto dissolved in 6 mL of tetrahydrofuran. The mixture was trans- TPM. From 3-DX a subsequent dehydration can also occur, ferred to a Teon® mold and the solvent was allowed to leadingtocis/trans-3,4-dideoxyxylos-3-enone(cis/trans-3,4-DXE). Thisjournalis©TheRoyalSocietyofChemistry2017 RSCAdv.,2017,7,985–996 | 989 View Article Online RSCAdvances Paper e. c n M. Lice Ad 4:42 porte 2n 2:U 023 1n 3.0 2o 3/4/buti d on Attri wnloademmons DoCo 7. ve 01ati y 2Cre Scheme2 Majorpathways,intermediatesandproductsintheconversionofpentosesbySn-Beta.Compoundabbreviations:3-deoxyxylosone ara (3-DX), cis-3,4-dideoxyxylos-3-enone (cis-3,4-DXE), trans-3,4-dideoxyxylos-3-enone (trans-3,4-DXE), 2,5-dihydroxy-4-methoxy-pentanoic 4 Januunder dacimidetmhyeltahcyeltaelst(eFr-D(DMMAP),Mg),ly3co-dlaeldoexyhpydenetodnimoleatchtyolneac(eDtaPlL)(,GtAra-nDsM-2A,)5,-mdiheythdyrloxgyly-c3o-psiednetsen(MoiGc),acmidetmhyelthlayclteasteter(M(DL)P,Mm),eftuhryflur4a-lm(Fe)t,hfouxryfu-r2a-l n 0ed hydroxybutanoate(MMHB),methylvinylglycolate,(MVG)and2,4,5-trihydroxy-3-pentanoicacidmethylester(TPM). d oens ec Publishcle is li The trans-3,4-DXE isomer can undergo reactive esterication products(3:5),whileSn-Beta(PT)resultedinalowerDPMyield Article. This arti fleuardfuinragl tvoiaDaPMthiwrdhidleehcyisd-r3a,4ti-oDnXEsteips.aInltikereelystipnrgelcyu,r3s-odreofoxyr odfiff2e3r%enc(Teaibslelik1e,leynattrtyri2b)uatanbdleshtoowthede baalloawnecreroaftiBor(ø1n:st2e)d.Tahnids ss xylosonehaspreviouslybeenreportedasanintermediateinthe Lewis acidity in the two materials. Sn-Beta (PT) contains more e c Ac formationoffurfuralfrompentoses.27,28Inthecurrentstudy,we defects due to being synthesised by a post treatment method, en oen nd that the yields of furfural derivatives and DPM are likely resulting in a more Brønsted acidic character.39,53 Addi- p O correlated, supporting that this is indeed an important inter- tionally, the different preparation methods may lead to mediateintheformationoffurfuralspeciesusingLewisacidic a different incorporation of tin into the *BEA siliceous catalysts. This interpretation is furthermore supported by the matrix.39,53,54AnindicationofthedifferentaciditybalanceforSn- use of the Brønsted acidic Al-Beta as the catalyst, resulting in Beta(HT)andSn-Beta(PT)isseenwhencomparingtheiryields theformationofonlytraceamountsoffurfuralproducts(1%) ofMGbeing6%and23%,respectively.Ofallthetin-containing and no detectable DPM. In contrast, Sn-Beta forms 11–17% silicates tested, the small pore Sn-MFI material displays the furfural products and 23–33% DPM under comparable condi- lowest selectivity towards DPM and dehydration products. The tions.AsmallamountofDMPMwasalsoobservedasaproduct. main products formed aer two hours are methyl glycosides, This is likely formed via Michael addition of methanol to 3,4- indicatingthatthepentosesarenotconvertedpreferentiallyvia DXE,priortoa1,2-hydrideshi,therebybeinganalogoustothe Lewisacidcatalysedpathwaysbutinsteadhavetimetoundergo formationofMMHBfromtetroses.20,21 acetalisationreactionswhicharetypicallycatalysedbyBrønsted acids.55Othertin-containingsilicatessuchastheorderedmes- Testingofdifferentcatalysts oporous materials Sn-SBA-15 and Sn-MCM-41 were also active forthe formation ofDPM, resultingin yields of12% and 16% Signicant yields of DPM (10–33%) were obtained only for yield,respectively.Thesecatalystsallbelongtothegroupoftin- catalysts containing tin incorporated into a siliceous matrix containingsilicatesandareallabletoformDPMinsignicant (Table 1, entries 1–5). A comparison of the yields of products yields.Incontrast,materialshavingtinoutsideofthesiliceous obtainedfromxyloseusingthedifferenttin-containingsilicates matrix,suchasdispersedSnO nanoparticlesonSi-Beta,didnot is shown in Fig. 1. The products are grouped into the three 2 catalysetheformationofDPMunderthesereactionconditions categoriesmentionedabove,accordingtotheprimaryreaction (Table 1, entry 6). This nding highlights the importance of pathwaysresponsiblefortheirformation.ThehighestDPMyield successfully incorporating tin in the silicate matrix to obtain of33%wasobtainedusingSn-Beta(HT)(Table1,entry1)which catalyticallyactiveheterogeneouscatalysts. also resulted in the highest ratio of DPM to total dehydration 990 | RSCAdv.,2017,7,985–996 Thisjournalis©TheRoyalSocietyofChemistry2017 View Article Online Paper RSCAdvances Table1 Conversionofxyloseusingavarietyofcatalystsa Retro-aldol Dehydration Carbon XYL, MG, GA-DMA, ML, MVG, MMHB, DPL, TPM/DMPMb, FURc, DPM, Total, balance, Entry Catalyst % % % % % % Total,% % % % % % % 1 Sn-Beta(HT) n.d. 4 2 14 2 <1 19 10 13 11 33(3) 68 90(4) 2 Sn-Beta(PT) n.d. 23 3 11 <1 <1 15 6 9 17 23(1) 55 93(3) 3 Sn-MFI <1 30 6 17 1 <1 24 3 3 10 11(1) 27 82(5) e. 4 Sn-MCM-41 n.d. 23 4 12 <1 <1 18 6 14 20 16(1) 57 98(5) c n 5 Sn-SBA-15 <1 32 6 11 <1 <1 18 3 10 18 12(1) 42 92(6) M. Lice 6 SnO2-Betad 53 42 2 <1 <1 <1 3 1 2 1 <1 6 104(7) Ad 7 Ti-Beta <1 48 7 11 3 <1 22 4 7 5 <1 16 86 24:42 nporte 89 ZArl--BBeettaa <61 3892 1n2.d. 1n0.d. 2n.d. <n1.d. 205 2n.d. 2n.d. 14 n<1.d. 19 8793(1) 2:U 023 1n 3.0 1101 SBil-aBnekta 1838 462 5<1 <21 <<11 <<11 18 n2.d. n3.d. <31 n<1.d. 18 9761(1) 2o 3/4/buti aAllreactionsemployedthestandardreactionconditions:360mgxylose(8.3wt%),4gmethanol,180mgcatalyst,2h,160(cid:1)Cand600rpmstirring. d on Attri RpreoadcuticotnssawreerperpoevrifdoerdmiendTinabtrlieplSi2ca.tnes.da.n¼dsntoatnddaertdecdteedvi.aRtieofnesrotofthScehleamstedi2giftoarrepgroivdeunctinapbabrreenvitahteisoinssf.obrDCPomMb;fiunleldvayliueeldssan(cdardbeovnia%tio)nosff2o,r4a,5ll- wnloademmons tfruirhfyudrarolxdyi-m3-eptehnytlaancoeitcala.cdidDmispetehrsyeldesStnerOa2nndan2o,5p-darihtiycdlersoxoyn-4S-mi-Beethtao.xy-pentanoicacidmethylester.cCombinedyields(carbon%)offurfuraland DoCo 7. ve 01ati y 2Cre lactates.20 The formation of DPM, in contrast, occurs via 4 Januarunder a athdeitffiner-ceonnttraeiancitniognsipliactahtwesa.yTthheastaimsseetermenindgwlyasonrelypocratteadlyfsoerdthbey n 0ed formation of THM from hexoses using the same types of d oens materials.26 The highly Brønsted acidic Al-Beta was found to ec Publishcle is li cwohnivcehrtisxiynloascecoinrdtoanmceetwhiytlhgplyrceovisoiduesswnditihngas.h56igNhosfeolremctaivtiiotyn, Article. This arti odfetDecPtMedw(caas.1o%bs)e.rved, while small amounts of furfural were s We would like to draw attention to the yields of furanic s e cc products and DPM in the comparison of Zr-Beta and Ti-Beta A n with all the tin-containing silicates. Low yields of furanic e Op products (4–5%) are observed for the zirconium and titanium materials while all tin-containing silicates form substantially higher yields (10–20%). This observation supports the afore- mentionedhypothesis,thatthemajorityofthefuranicproducts isformedviaa3-DXrouteforthetin-containingsilicates.The inabilityofthetitaniumandzirconiummaterialstocatalysethe formationof3-DXfromxylosethusalsopreventsasubstantial co-productionoffuraniccompounds. Fig. 1 Product distribution of tin-containing silicates based on data from Table 1. Reaction conditions: 0.360 g xylose, 0.180 g catalyst, Effectofreactionparametersandco-solutesforDPM 4.0gmethanol,160(cid:1)C,2hours. formationusingSn-Beta The catalyst screening claried that Sn-Beta gives higher DPM yields than other tin-containing silicates. We therefore assessed The purely siliceous material Si-Beta did not catalyse the thereactionparametersindetailusingSn-Beta(HT)asthecata- formation of signicant amounts of DPM, and the main lyst.Tothisend,wevariedthereactiontemperature(140–180(cid:1)C), productobservedwasMG(Table1,entry10).Catalystshaving the catalyst to substrate ratio (0.125–1.0), the concentration of othermetalsthantinincorporatedintotheframeworksuchas xylose in the reaction solution (8.3–23 wt%) and examined the titanium, zirconium and aluminium did not form signicant effect of adding alkali co-solutes in the form of potassium yieldsofDPMfromxyloseeither(Table1,entry7–9).However, carbonate.Furthermore,wetestedifotherpentosescouldbeused both Ti-Beta and Zr-Beta gave appreciable yields of retro-aldol forDPMformation.Fromthesestudies,itwasdeducedthathigh products (22–25%), which is in accordance with previous catalysttosubstrateratiosandtheabsenceofalkalico-solutesare reports of these materials being active for the formation of importantparameterstoobtainhighyieldsofDPM. Thisjournalis©TheRoyalSocietyofChemistry2017 RSCAdv.,2017,7,985–996 | 991 View Article Online RSCAdvances Paper TheeffectofreactiontemperatureontheyieldofDPMwas 0.5.Surprisingly,increasingtheconcentrationdidnotlowerthe insignicantandsimilaryields(31–34%)wereobtainedinthe yieldofDPMandusinga23wt%solutionofxyloseinmethanol temperature range of 140–180 (cid:1)C (Table S4†). The reaction gaveasimilaryieldof32%asan8.3wt%solution(TableS3†). temperatureeffectappearedtobemorepronouncedforyields Finally,twootherpentoses(riboseandlyxose)weretestedas ofotherreactionproducts,withhighertemperaturesfavouring substrates and found to give DPM yields of 30% and 31%, retro-aldol products (9% difference) and lower temperatures respectively(TableS3†). favouringfuranics(8%difference). Ithadpreviouslybeenshownforhexosesthatalkalico-solutes e. signicantly diminish the yield of THM and furanic products, Polymerisationpotential c n leadingto increasedyieldsofretro-aldolproducts, from 30%in InordertoevaluatetheusefulnessofDPMasanovelpolyester M. Lice theabsenceofalkalito75%inthepresenceof0.065mMofadded monomer, and having shown that DPM can be formed in 4:42 Aported pthoetacsosniuvmerscioarnboofnpaeten.1t8osWese(Fnigd.t2h),aitllaunstarnatailnoggothuasteoffpetcitmeaxlisytiselfdosr aDcPcMeptwaabslepyeierflodrsm(aebdovaet3la0r%ge),rtshceasleyn(t1hLes).isDaunedtpoutrhiecasitmionploerf 2n 023 12:n 3.0 U obfyDICPPMmreeaqsuuirreemaesntrtisctthcaotnatrboalcokfgarolkuanlidcaolnkatalimleinvealnotfs.1W.3ewftopupnmd seyxnptehnesseisofroautleowoefrSonv-eBreatlal D(PPTM), tyhieisldc.aFtarolymsttwhaesseulsaerdgea-tsctahlee d on 3/4/2Attributio nwaatsTinhpgerefcrsaoetmnatlyteshvteetnobosurunobsdsieltirrcaa“ttaeelkrgaaltlaiisosfwrweaaesr”ev.caorniedditfiroonms,0p.o1s2s5ibtoly1o.0riogni- DpexrPpeMperairmewdeansitnss,ay2cnc.t6ehpegtsaiosbfeled$.a9mH4%oauvinpntugsr,ewsh(eaosbweencsatimtmheaattiendDtePbreMyst1eHcda-NninMibRtes) wnloademmons wcoenigshtatntbaatsi8s.,3wwth%ilexylkoeseep.iInngterethsteingsluyb,satrsattreongcodnecpeenntrdaetniocne ubyseSaeslsaapnodlycmo-ewrobrukielrdsinthgabtloMckV.GItchanasbperecvoi-opuosllyymbeereisnedshwowitnh DoCo on catalyst loading was found, as selectivity towards DPM lactic acid with a 1,2-linkage to afford a polyester material 017. ative increasedsignicantlyfromacatalysttosubstrateratioof0.125 having pendant vinyl groups available for post functionalisa- y 2Cre (19%DPM)upto0.5(34%DPM)(TableS4†).Theformationof tion.23Additionally,ithasrecentlybeenreportedthatMVGcan 4 Januarunder a rweittrho-ainldcorelapserdodcuacttaslyfsotlltoowesdubtshtreatoeppraotsioitseftrroemnd,adceocmrebaisninedg vbiea caomnveetrattehdesiinstroeadcitmioent.h57y,5l8(TEh)-i2s,5n-edwihypdrorodxuychtehx-a3s-eanlesodiboaeteen, n 0ed yieldof32%atacatalysttosubstrateratioof0.125tojust15% successfully co-polymerised with lactic acid.57 In contrast to d oens ataratioof1.0. MVG, DPM contains both a secondary and a primary alcohol, Publishecle is lic wasThteeseteffde,ctkoeefpthinegxytlhoeseccaotanlcyestnttroatsiuobnsitnrattheerraetaiocticoonnmstaixntturaet wtohpicohorprseevleencttisvitthyecuosnetroofl.clHasoswiceavlepr,oelynmzyemrisaatitciopnoclyamtaelyrsistsatdioune s Article. This arti mmpreoimtnhoaomrdysearnsp.d5e9r,s6m0ecitoEnspdpoaelcryyimaalellycrioshathotielosneennoazfbylmseusecthhseehlseipcgethicvliyitycfusbnynectttwhioeenseainsl s ce of functional linear polymers that cannot be prepared using c A n chemo-catalysis.61,62 Unfortunately, homo-polymerisation of e p DPM was unsuccessful and resulted only in the formation of O oligomers. As an alternative to homo-polymerisation, co- polymerisations wereconducted usingthe commerciallyavail- able monomer ethyl 6-hydroxyhexanoate (E6-HH) as shown in Scheme 3. Polymerisation of pure E6-HH affords poly- caprolactone (PCL) which is a linear and biodegradable poly- ester produced on industrial scale. Co-polymerisation with DPM could be envisaged to be a useful way to modify the propertiesofPCL.ThisapproachincorporatesDPMintolinear polymers with a linear 1,5-linkage, leaving the secondary alcoholandolenmoietiesavailableforpost-functionalisation (Scheme3,polymerI). Theenzymaticco-polymerisationsbetweenDPMandE6-HH wereperformedat60(cid:1)Cinbulkmonomerinaccordancewith the general procedure described in the Experimental section. TheNMRspectrumoftheresultingpolymer(Fig.3)showsthat that the vinylic hydrogen atoms from DPM are present, while thealcohol,alkeneandesterfunctionalgroupswereconrmed byFT-IRspectroscopy(Fig.S6†). Fig.2 ProductdistributionatdifferentalkaliconcentrationsusingSn- The polymer synthesis procedure was varied to study the Beta, based on data from Table S5.† Reaction conditions: 0.360 g xylose,0.180gSn-Beta(HT,Si/Sn¼150),4.0gmethanol,160(cid:1)C,2 effects of feed ratio and polymerisation time on the resulting hours.YieldsofTPMandDMPMandDPLarenotincludedinthisgraph. polymers. Polymerisation time was studied by conducting co- RefertoScheme2forabbreviations. polymerisation experiments using a DPM to E6-HH molar 992 | RSCAdv.,2017,7,985–996 Thisjournalis©TheRoyalSocietyofChemistry2017 View Article Online Paper RSCAdvances testedreactiontimesreasonabledegreesofpolymerisation(M w ¼10000–12350gmol(cid:4)1)andpolydispersityindices(PDI¼2.1– 2.5) were obtained, comparable to typical results from enzy- maticpolymerisationofmonomerscontainingbothsecondary andprimaryalcohols.61,62 These ndings clearly showed that DPM was more chal- lenging to polymerise than E6-HH, which was also evident by DPM being unable to homo-polymerise. Nevertheless, DPM e. should become incorporated at longer polymerisation times c n andhigherDPMfractionsinthefeed(Table2). M. Lice A study of varying the feed ratio of E6-HH to DPM from Ad 4:42 porte athmeocola-rporalytmioeorfi0n.c2r2eatose0d.6w6itshhoinwcerdeathseadttrhaetioco.nTtheinstleoafdDtPoMfuinll 2n 023 12:n 3.0 U itnimcoerspoorfa7ti2onhoafnDdPMmoilnetcoultahrercaoti-opsolaymboevres 0a.t4p4o.lDymesepriitseatfiuonll 2o d on 3/4/Attributi Scheme 3 Enzymatic co-polymerisation of DPM and ethyl 6- 0imn.6oc6olermcpuoolrlaaartriworaentiigoho,tfrsesoDpfPeoMcnt,ilvyet4lhy5.e0sM0eoalnpedcouly3lma7r0e0wriegsiagmthiootsnl(cid:4)sa1bforoevrseu01l.0t4e40d0a0nindg 017. Downloadeative Commons ashounynpddeprofosoxusryebmhdseeliyxsqaourneecopncarutetresfeou(nEnn6tcee-tdiiHothiHnnea)rtluihscseaaitnrsibogconhCn.eamTonhfedetidfhoaerreaocanllcaettarfiiiortncynit.cicomafoliptiehatesieestB,hbio(CulstAoLc-naBlny) mogabottTela(cid:4)dhin1ebeadtyshfDeoorSrbmCstahelraevnspeedrdocpsowhe-iprottohwieleys0dm.o2egf2rliaasmlsalstotilhtoarenarsncr.soai-ttpiiooonlyDmtPeMemrspceworuearltdeurinensovte(sTbtgie)- y 2Cre between (cid:4)49 (cid:1)C to (cid:4)56 (cid:1)C, which is typical for aliphatic poly- n 04 Januared under a eTdsehtteeerrmsmeailnntidendgcottonembrepme4sra2tt.h8uer(cid:1)eC(eTaxminb)dlaetTnm0a.1tdu2ercmereooalfastrehdreawtpiioothloymfinDecrPrMecahsawiinangs. d oens content of DPM to 7.5 (cid:1)C at 0.66 molar ratio DPM. The incor- ec Publishcle is li ptoo-rcahtaioinnpoafcDkPinMgcreleqaurilryepdrfeovrenthtsetphoelyrmegeurlatorictyryasntadllcilsoes,ethcehraeibny- Article. This arti redTuhciensgetihneitimaleslttiundgietsemclpeaerrlaytusrheo.wthatDPMcanbesuccess- s fully polymerised with other similar monomers thereby s ce providing access to functional polymers. Furthermore, the c A n degreeofincorporationmaybeusedtomanipulatethephysical pe Fig.3 1HNMRassignmentoftheco-polymerproduct,poly(E6-HH- propertiesoftheco-polymer. O co-DPM),fromTable2entry4. Post-functionalisation ratioof0.22andvaryingthereactiontimes(Table2,entries2– Post-functionalisationofpolymersoffersthepossibilitytotailor 4). The shortest polymerisation time of 18 h resulted in the theirproperties. TheDPM containingco-polymers were tested incorporation of approximately 55% (0.12 molar ratio) of the for their ability to undergo functionalisation of the a-hydroxyl DPM from the feed into the co-polymer. By increasing the and olenic groups (Scheme 3). Functionalisation of the a- polymerisation time to rst 42 h and subsequently to 72 h, hydroxyl groups of DPM was performed using triuoroacetic incorporation was increased to 77% (0.17 molar ratio). At all anhydride (TFA), a highly reactive reagent widely used in Table2 Enzymaticco-polymerisationofE6-HHandDPMa Entry Timeh FeedMRb Prod.MRb,c T d,(cid:1)C T d,(cid:1)C M e,gmol(cid:4)1 M e,gmol(cid:4)1 PDIe g m n w 1f 18 0 0 (cid:4)60.2 48.9 3600 4700 1.3 2 18 0.22 0.12 (cid:4)49.3 42.8 5150 10050 2.1 3 42 0.22 0.14 (cid:4)49.3 42.5 4490 10750 2.4 4 72 0.22 0.17 (cid:4)50.0 34.2 5000 12350 2.5 5 72 0.44 0.44 (cid:4)55.5 15.1 1900 4500 2.4 6 72 0.66 0.66 (cid:4)52.3 7.5 1760 3700 2.1 aAllreactionswereperformedat60(cid:1)Candthepressurewasheldat200mbarfor2hwhereaeritwasreducedto5mbarinaccordancewith optimisationsperformedwithE6-HH(seeESI).bMolarratio(MR)listedasDPM/E6-HH[molmol(cid:4)1].cDeterminedby1HNMR.dDetermined byDSC.eDeterminedbySECinTHFusingPSstandards.fUsingonlyE6-HHasmonomer. Thisjournalis©TheRoyalSocietyofChemistry2017 RSCAdv.,2017,7,985–996 | 993 View Article Online RSCAdvances Paper hydroxyl labelling of polymers, allowing for clear detection of Table3 Advancingandrecedingwatercontactanglemeasurements functionality by NMR analysis.63,64 The structure of the TFA forPCL,PECD–PCLandPECD(TFA)–PCLfilmsa modiedco-polymer(Scheme3,polymerII)wasveriedby1H Film AdvancingWCAdeg RecedingWCAdeg NMR(seeexperimentalsection“Thiol–enefunctionalisationof poly(E6-HH-co-DPM)”),showingthatfullfunctionalisationwas PCLb 90(1) 46(1) achieved. PCL 85(2) 46(2) Additionally, thiol–ene chemistry was used to demonstrate PECD–PCLc 75(1) 38(2) thereactivityoftheintra-chainalkene.23Thiol–enechemistryis PECD(TFA)–PCLd 93(2) 36(2) ce. awell-establishedprotocolforfunctionalisationofpolymersby amAelalswuraetemrecnotnstaocfttahnrgeelesdi(ffWeCreAn)twderroepdsetaetrmdiiffneerdenatspavoesriatigoenssoofnthtrheee n formation of alkyl sulphides via reaction of a thiol and an M. Lice alkeneusingradicalchemistry.65,66Here,aphotoinitiator(2,2- ppoarlyemntehressuisr.facbeWaCnAdsvtaanludeardfodrevPiaCtLionfsroomfthleitelarasttudrieg.6i8tacreThgievenlimn 4:42 Aported dwiimtheathsoexleyc-2ti-ponheonfytlhaicoeltocpomhepnoounned,sD(SMchPAem) ew3a)stousileldusttroagteeththeer cToFnAtafuinnecdtio1n0awlist%edppoollyy((EE66--HHHH--ccoo--DDPPMM))..dThe lmcontained10wt% 2n 023 12:n 3.0 U potTenhteiaflufnocrtpioonsat-lpisoaltyimoneriosfatDioPnMfusnucbti-ounnaitlsisaintiotnh.e thiol–ene Downloaded on 3/4/2Commons Attributio bh3fpeox,eoilnptllpwyoedmorweeilermyieennmrdegenu3sdrtu0psismboIasniwItnnIiaadtifuss–uheen1)end.c0dtet0sPitd%oeoyonriouemarclbldoiislnsineoanevlbtgdueioorbtnnshiuidl.eoistinphTynr,ihgogoiwthfoo1ielntt–Hshhetiennctaetohfennuendrvnseecliarett1csiiaHetoisiosn–otnw1an3sli(sCittSsehcevrihdiNancerMatmichelolRdeey- crppWeohocC-lopeyAbd(oEiilucyn6imp-gtHyWetHoor,fC-9cwtAo3hh-(cid:1)weDi,caPwhslMhmnsi)hocdtohreuawsiffeesuedtleoctexttethdphdaeeitcfnrtteohuadmenofrsbriiyonnlsemectneriedmniainnsticehgsreeisinantcisoltitlh-nhpaegeomltayuphdmohevrieahpirnnhy.acdTiitlrnheiocdge-. 017. ative polymer materials in DMSO and chloroform prevented Bsuortfhacreespurltospeshrtoiews tohfatththeetchoi-npolylmmerbliesnadb,leantodmthoadtifypothste- y 2Cre conclusive studies of the regioselectivity inthe thiol–ene reac- modication of the co-polymer permits exploitation of the n 04 Januared under a gtmiroaenrcsi.anpgWtoreeetafhogauennnotdsl,t(mhScaahtkeiimnngepia3tr,tpiocpusosllaiybrmlemerteorIcIfIaubpl–tlcyo)accowenteivrceeratecffitdheecatiinvnde- fulmnctbiolennadlsg.roupsforfurthermodicationofthesurfaceofthin d oens chain double bond, clearly demonstrating the polymers high Article. PublisheThis article is lic ptcaooloirsthreaeantsvitopeianoalnnifdnoiarntphgfpuerpnopecxontiildmoyemnanatetelrilasyoalkb1tie0sone-nfero.vsle.Id6nd7-lTchohhweareeeirnhinriageilhaskceettnhixvteuiestsnyaetcrxooetfmreafspoutranidmrceitnadiotaentrdoy- CIbtinunoi-tlchdoneinnctcgaulibrunrlieosnncgiktossDintluPicdMayt,ecswaneashbacevaestaysnlyhtshotsewsniinsethdyiaeftlrdothsmeupnpeontvoetol3sp2eo%slyuewssiitntehgr s andunderlinesthepotentialofin-chainalkenesforpreparation ces offunctionalpolymers. xylose concentrations of 23 wt%. This approach provides c A a simple and low cost route from a plentiful and sustainable n e feedstock to an intriguing chemical product. Future improve- p O Co-polymerblendswithpolycaprolactoneinthinlms mentstotheDPMsynthesismayencompasswaystosuppress theformationoffuranicsorofretro-aldolproducts,ortobetter The prepared co-polymers have a high structural similarity to control the formation of ester products from 3-DX. DPM has PCLandthereforeblendsbetweensomeoftheco-polymersand PCL were investigated. PCL oen nds uses in biomedical beenshowntobeaninterestingmonomerforthepreparation of functional polyesters in co-polymerisation with E6-HH. devices, where control of surface properties and functionality Enzymatic polymerisations were effective for the synthesis of are highly desired properties and therefore simple blending the highly functional polyesters with 0.17 to 0.66 molar ratio couldbeaninterestingapplicationofthenewco-polymers. Three different lms consisting of pure PCL, a PCL blend content of DPM. The co-polymers could easily be post- with10wt%poly(E6-HH-co-DPM)(PECD–PCL)andaPCLblend functionalised using either TFA or thiol–ene chemistry to with 10 wt% triuroacetic acid functionalised poly(E6-HH-co- extend the potential applications of these co-polymers. As an DPM) (PECD(TFA)–PCL) were prepared by solvent casting and example,simpleblendswithPCLwereinvestigatedanditwas hot-pressing. The prepared lms were investigated by water shown howtheco-polymer couldbeusedtoaffectthe surface propertiesofthepolymerlm. contactangle(WCA)measurementstodeterminetheimpacton The chemoenzymatic approach described herein thus surfacepropertiesoftheblend(Table3). ThepurePCLlmhadanadvancingWCAof85(cid:1),whichwas enables future bio-reneries to better utilise pentoses from reduced to 75(cid:1) by blending with the DPM co-polymer. This hemicellulose-containing biomass, providing the chemical industrywithnewtypesofinterestingpolymerbuildingblocks. shows the impact of the free hydroxyl groups from the co- polymer, andcouldbeexploited toincreasethehydrophilicity ofthethinlm.ThiswascorroboratedwiththerecedingWCA, Acknowledgements which is reduced by almost 10(cid:1) for the blend, indicating the presence of more polar groups in the system. Conversely, We gratefully acknowledge funding by the Bio-Value platform blending PCL with the triuroacetic acid functionalised (biovalue.dk) under the SPIR initiative by The Danish Council 994 | RSCAdv.,2017,7,985–996 Thisjournalis©TheRoyalSocietyofChemistry2017
Description:The list of books you might like
