ADVISORY BOARD L. H. Gade D. Darensbourg UniversitätHeidelberg TexasA&MUniversity Germany CollegeStation,Texas,USA M. L. H. Green H. B. Gray UniversityofOxford CaliforniaInstituteofTechnology Oxford,UnitedKingdom Pasadena,California,USA A. E. Merbach P. A. Lay LaboratoiredeChimieetBioanorganiqueEFPL, UniversityofSydney Lausanne,Switzerland Sydney,Australia P. J. Sadler J. Reedijk UniversityofWarwick LeidenUniversity Warwick,England Leiden,TheNetherlands K. Wieghardt Y. Sasaki Max-Planck-Institut HokkaidoUniversity Mülheim,Germany Sapporo,Japan AcademicPressisanimprintofElsevier 225WymanStreet,Waltham,MA02451,USA 525BStreet,Suite1800,SanDiego,CA92101-4495,USA 32JamestownRoad,LondonNW17BY,UK TheBoulevard,LangfordLane,Kidlington,Oxford,OX51GB,UK Radarweg29,POBox211,1000AEAmsterdam,TheNetherlands Firstedition2014 Copyright©2014,ElsevierInc.Allrightsreserved Nopartofthispublicationmaybereproduced,storedinaretrievalsystemortransmittedin anyformorbyanymeanselectronic,mechanical,photocopying,recordingorotherwise withoutthepriorwrittenpermissionofthepublisher PermissionsmaybesoughtdirectlyfromElsevier’sScience&TechnologyRights DepartmentinOxford,UK:phone(+44)(0)1865843830;fax(+44)(0)1865853333; email:permissions@elsevier.com.Alternativelyyoucansubmityourrequestonlineby visitingtheElsevierwebsiteathttp://elsevier.com/locate/permissions,andselecting ObtainingpermissiontouseElseviermaterial Notice Noresponsibilityisassumedbythepublisherforanyinjuryand/ordamagetopersonsor propertyasamatterofproductsliability,negligenceorotherwise,orfromanyuseor operationofanymethods,products,instructionsorideascontainedinthematerialherein. Becauseofrapidadvancesinthemedicalsciences,inparticular,independentverificationof diagnosesanddrugdosagesshouldbemade LibraryofCongressCataloging-in-PublicationData AcatalogrecordforthisbookisavailablefromtheLibraryofCongress BritishLibraryCataloguinginPublicationData AcataloguerecordforthisbookisavailablefromtheBritishLibrary ISBN:978-0-12-420221-4 ISSN:0898-8838 ForinformationonallAcademicPresspublications visitourwebsiteatstore.elsevier.com PrintedandboundinUSA 14 15 16 17 11 10 9 8 7 6 5 4 3 2 1 CONTRIBUTORS AntonellaAngelini DepartmentofChemistry,UniversityofBari,Bari,Italy MicheleAresta CIRCCViaCelsoUlpiani27,Bari,Italy ArnoBehr TechnicalChemistry,DepartmentofBio-andChemicalEngineering,TechnicalUniversity ofDortmund,Dortmund,Germany RobertH.Carr Huntsman(Europe)bvba,Kortenberg,Belgium DonaldJ.Darensbourg DepartmentofChemistry,TexasA&MUniversity,CollegeStation,Texas,USA Zhen-FengDiao StateKeyLaboratoryandInstituteofElemento-OrganicChemistry,NankaiUniversity, Tianjin,P.R.China AngelaDibenedetto CIRCCViaCelsoUlpiani27,andDepartmentofChemistry,UniversityofBari,Bari,Italy EtsukoFujita ChemistryDepartment,BrookhavenNationalLaboratory,Upton,NewYork,USA KyleA.Grice DepartmentofChemistryandBiochemistry,UniversityofCalifornia,SanDiego,LaJolla, California,USA Liang-NianHe StateKeyLaboratoryandInstituteofElemento-OrganicChemistry,NankaiUniversity, Tianjin,P.R.China RichardH.Heyn SINTEFMaterialsandChemistry,Blindern,Oslo,Norway YuichiroHimeda NationalInstituteofAdvancedIndustrialScienceandTechnology,Tsukuba,Ibaraki,and JapanScienceandTechnologyAgency,Kawaguchi,Saitama,Japan IvoJacobs HuntsmanHollandBV,Rotterdam,TheNetherlands KonstantinKraushaar Institutfu¨rAnorganischeChemie,ArbeitsgruppeSiliciumchemieundChemische Materialwissenschaft,TechnischeUniversita¨tBergakademieFreiberg,Freiberg,Germany ix x Contributors EdwinKroke Institutfu¨rAnorganischeChemie,ArbeitsgruppeSiliciumchemieundChemische Materialwissenschaft,TechnischeUniversita¨tBergakademieFreiberg,Freiberg,Germany CliffordP.Kubiak DepartmentofChemistryandBiochemistry,UniversityofCalifornia,SanDiego,LaJolla, California,USA Yu-NongLi StateKeyLaboratoryandInstituteofElemento-OrganicChemistry,NankaiUniversity, Tianjin,P.R.China Hannu-PetteriMattila ThermalandFlowEngineeringLaboratory,A˚boAkademiUniversity,Turku,Finland JamesT.Muckerman ChemistryDepartment,BrookhavenNationalLaboratory,Upton,NewYork,USA KristinaNowakowski TechnicalChemistry,DepartmentofBio-andChemicalEngineering,TechnicalUniversity ofDortmund,Dortmund,Germany DanaSchmidt Institutfu¨rAnorganischeChemie,ArbeitsgruppeSiliciumchemieundChemische Materialwissenschaft,TechnischeUniversita¨tBergakademieFreiberg,Freiberg,Germany AnkeSchwarzer Institutfu¨rAnorganischeChemie,ArbeitsgruppeSiliciumchemieundChemische Materialwissenschaft,TechnischeUniversita¨tBergakademieFreiberg,Freiberg,Germany Wan-HuiWang NationalInstituteofAdvancedIndustrialScienceandTechnology,Tsukuba,Ibaraki,and JapanScienceandTechnologyAgency,Kawaguchi,Saitama,Japan Zhen-ZhenYang StateKeyLaboratoryandInstituteofElemento-OrganicChemistry,NankaiUniversity, Tianjin,P.R.China RonZevenhoven ThermalandFlowEngineeringLaboratory,A˚boAkademiUniversity,Turku,Finland PREFACE Volume66ofAdvancesinInorganicChemistryisathematicvolumedevotedto CO chemistry, co-edited by Michele Aresta from the University of Bari, 2 Italy. At the recent 4th EuCheMS Chemistry Congress in Prague, August 2012, a special symposium on CO chemistry was organized as part of 2 the Inorganic Chemistry Program. Understanding the important industrial and environmental role of CO effluents is a multidisciplinary challenge to 2 scientists working on various aspects of CO chemistry with the ambitious 2 targetofconvertinglargevolumesofCO foraneffectivecarbonrecycling. 2 Should the latter be implemented, it would result in a significant environ- mental benefit with fossil reserves preservation for future generations. Anumberofspeakersatthissymposiumandotherleadingscientistsworking inthisareawereinvitedtocontributetothisspecialissue.Thecontributed chapters cover an important part of CO utilization strategies. 2 In the opening chapter, Donald J. Darensbourg presents a personal account on his adventures in the synthesis of copolymers from CO and 2 cyclic ethers. This is followed by a chapter on the synthesis of organic car- bonates by Angela Dibenedetto and Antonella Angelini. In Chapter 3, Richard H. Heyn, Ivo Jacobs, and Robert H. Carr report on the synthesis ofaromaticcarbamatesfromCO andtheimplicationsforthepolyurethane 2 industry. This is followed by a chapter on the reactions of CO and CO 2 2 analogs with reagents containing Si–H and Si–N units reported by KonstantinKraushaar,DanaSchmidt,AnkeSchwarzer,andEdwinKroke. InChapter5,KyleA.GriceandCliffordP.Kubiakreportonrecentstudies of rhenium and manganese bipyridine carbonyl catalysts for the electro- chemical reduction of CO . In the subsequent chapter, Wan-Hui Wang, 2 Yuichiro Himeda, James T. Muckerman, and Etsuko Fujita discuss the interconversionofCO /H andformicacidundermildconditionsinwater 2 2 andfocusonliganddesignforeffectivecatalysis.Chapter7isdevotedtothe catalytic hydrogenation of CO to formic acid by Arno Behr and Kristina 2 Nowakowski.This is followed by a report on theconversion of “exhaust” carboninto“working”carbonbyMicheleAresta,AngelaDibenedetto,and Antonella Angelini. In Chapter 9, Yu-Nong Li, Liang-Nian He, Zhen- Feng Diao, andZhen-Zhen Yang present areport on carbon capturewith simultaneous activation and subsequent transformation. In the final contri- bution,Hannu-PetteriMattilaandRonZevenhovenpresentanaccounton xi xii Preface the production of precipitated calcium carbonate from steel converter slag and other calcium-containing industrial wastes and residues. Wearemostappreciativeoftheeffortsoftheauthorsandtheircolleagues whohaveprovidedinformative,instructive,andauthoritativecontributions forthisthematicvolume.WebelieveresearchersinthefieldofCO chem- 2 istry will be encouraged by presented contributions in this volume. We invite readers in other fields of chemistry to acquaint themselves with the fascinating and intriguing chemical challenges awaiting us. MICHELE ARESTA CIRCC, University of Bari, Bari, Italy RUDI VAN ELDIK University of Erlangen-Nu¨rnberg, Erlangen, Germany October 2013 CHAPTER ONE Personal Adventures in the Synthesis of Copolymers from Carbon Dioxide and Cyclic Ethers Donald J. Darensbourg DepartmentofChemistry,TexasA&MUniversity,CollegeStation,Texas,USA Contents 1. Introduction 1 2. CarbonDioxideasaSourceofChemicalCarbon 3 3. CopolymersfromOxiranesandCarbonDioxide 4 4. BlockCopolymersofPolycarbonatesandLactides 12 5. TerpolymersfromOxiranesandCarbonDioxide 13 6. DepolymerizationofPolycarbonates 19 Acknowledgments 22 References 22 Abstract Thischapterfocusesonrecentadvancesinthedevelopmentofwell-definedmetalcat- alystsforthecouplingofCO andoxiranesfortheproductionofpolycarbonatesand 2 cyclic carbonates. Since this subject has been comprehensively covered in several reviewsrecently,thistreatmentwillcenteroncontributionsfromourlaboratorywithin thecontextofotherpublishedwork.Specialattentionwillbegiventoourcurrentstud- ies dealing with depolymerization pathways of polymeric materials derived from completelyalternatingcopolymerizationofCO andepoxides. 2 Keywords: Carbon dioxide, Copolymerization, Terpolymerization, Epoxides, Metal catalysts, Polycarbonates,Salen ligands 1. INTRODUCTION Theinterestofmyresearchprogramintheorganometallicchemistry ofcarbondioxidebeganinthemid-1970swhenwewereinvestigatingthe mechanistic aspects of group 6 metal carbonyl-catalyzed water–gas shift reactions.Thesestudieseventuallyledustoexaminingindetailtheinsertion AdvancesinInorganicChemistry,Volume66 #2014ElsevierInc. 1 ISSN0898-8838 Allrightsreserved. http://dx.doi.org/10.1016/B978-0-12-420221-4.00001-9 2 DonaldJ.Darensbourg reactionsofCO intoMdOHandMdOR(R¼alkyloraryl)bonds.We 2 and others definitively established that insertion of CO into metaldOR 2 bonds occurred in the absence of prior coordination of CO to the metal 2 center (1, 2). That is, the major interaction in the transition state (TS) involves the electrophilic carbon center of CO with a lone pair on the 2 nucleophilicoxygenatomoftheORgroupasdepictedinFigure1.1.Con- sistentwith thisinterpretation,therateofthisreactionishighlydependent onthenucleophilicityofthemetalalkoxidemoietysinceCO issuchapoor 2 electrophile. As indicated in Figure 1.1, the reaction is reversible although the metal carbonate is generally thermodynamically more stable than the corresponding metal alkoxide and CO . 2 The reaction described in Figure 1.1 is one of the pivotal steps in the couplingofCO andepoxidestoprovidepolycarbonatesandcycliccarbon- 2 ates(seeEquation1.1).Thisisparticularlyrelevantsincethemostprominent metal catalysts for this process, for example, (salen)CrCl (salen¼salicylaldimine), upon binding the growing polymer chain, are coordinatively saturated. In this chapter, I will describe our most recent advancesinthedevelopmentofwell-definedmetalcatalystsforthecoupling reactions of CO and cyclic ethers (oxiranes) for the production of poly- 2 carbonates or cyclic carbonates. These studies will focus on contributions fromourlaboratorywithinthecontextofotherpublishedwork.Thissub- jectmatterhasbeencomprehensivelycoveredinnumerousreviews,includ- ingonewhichchronologicallydescribeddevelopmentsinthisfieldstarting withthepioneeringeffortsofInoueandcoworkers(3).Priortosummariz- ingourrecentresultsontheutilizationofCO toproducepolymericmate- 2 rials, it is useful to assess the issues surrounding the use of CO in organic 2 synthesis. O O O + CO metal catalyst O + O O ð1:1Þ 2 O n polycarbonate cyclic carbonate d- O O C O d+ C [M] OR + CO2 [M] O [M] O OR R Figure1.1 CarbondioxideinsertionpathwayintometaldORbond. PersonalAdventuresintheSynthesisofCopolymersfromCO 3 2 2. CARBON DIOXIDE AS A SOURCE OF CHEMICAL CARBON Presently in the United States, we are experiencing the discovery of additional petroleum deposits and the development of new technologies foritsrecovery,albeitoftenwithanegativeenvironmentalimpact.Never- theless,ifwecontinuetoconsumethisfinitesourceofprereducedcarbonin particularasfuels,concomitantlyemittingtheoxidizedcarbontotheatmo- sphere, we not only will lead to climate change but also will exhaust this sourceof chemicalcarbon.This situationclearlydoes notsatisfytheEPA’s definitionofsustainability,thatis,“meetingtheneedsofthepresentwithout compromisingtheabilityoffuturegenerationstomeettheirownneeds.”At thispoint,theonlyreservoirsofcarbonforchemicalsynthesiswillbeimme- diatebiomassandcarbondioxide.Ofcourse,coupledwiththisoccurrenceisthe factthattheworldpopulationisprojectedtoincreaseby50%by2044to9 billion,alongwithanincreaseintheeconomiesofthisemergingpopulation growth. The current uses of CO for chemical synthesis are quite limited, with 2 the major industrial processes being the synthesis of urea, salicylic acid, methanol, and inorganic carbonates (4). More recently, a sizable quantity of CO is utilized in a greener synthesis of BPA-derived polycarbonate, 2 whichavoidstheuseoftheverytoxicphosgenereagent(seeEquation1.2). Thatis,AsahiKaseiCorporationhassolvedtheengineeringproblemsasso- ciated with the disfavored equilibria involved in the synthesis of diphenyl carbonatefromdimethylcarbonateviaethylenecarbonate,thelatterreagent beingreadilysynthesizedfromethyleneoxideandCO (5).Ofimportance, 2 thecoproductinthisreaction,ethyleneglycol,isacommoditychemicalthat isgenerallyproducedbyhydrationofethyleneoxide.Allotherreagentsare recycled in the process (see Figure 1.2): O O melt nPhO PhO + n HO OH O O C + 2n PhOH n ð1:2Þ Thelargestobstacleforestablishingindustrialprocessesbasedontheuse of CO as a raw material is the high energy required to transform CO 2 2 because of its low-energy level. Hence, processes involving nonrenewable sources of energy require the use of high-energy starting materials. 4 DonaldJ.Darensbourg O PhO OPh bis-phenol A PhOH BPA polycarbonate O O CO2 + O O O MeOH MeO OMe + HOCH2CH2OH DMC Ethylene glycol Figure1.2 AsahiKasei’snonphosgeneroutetoBPApolycarbonate,productsinredand recyclablesingreen. The reaction described in Equation (1.1) fits this requirement, being based on small-membered ring compounds and affording oxidized low-energy synthetic targets. 3. COPOLYMERS FROM OXIRANES AND CARBON DIOXIDE Our initial reportutilizing binary (salen)CrCl catalyst systemsfor the copolymerization of cyclohexene oxide or propylene oxide and carbon dioxide providedthestimulus for thedevelopment of the most productive andselectivecatalystscurrentlystudied(6,7).Thatis,theuseofthesecom- plexes and their cobalt(III) and aluminum(III) analogs, and their closely related porphyrin derivatives, has dominated studies leading to effective copolymerization processes of CO with a variety of epoxides (3). This 2 chemistryhasevolvedtothepointtodaythatmostactiveandselectivecat- alyst systems are composed of bifunctional catalysts where the cocatalyst is covalently attached to the salen ligand (8–10). Scheme1.1 summarizes theaccepted modeof reaction of these catalyst systems, where the cocatalyst is an onium salt composed of various anion initiators.Itisnoteworthytorecallfromourearlierstudiesinorganometallic chemistrythattheCO insertionstepdoesnotrequirepriorcoordinationof 2 CO to the coordinatively saturated metal center. Additionally, at modest 2 CO pressures where insertion of CO is not rate-limiting, the slow step 2 2 isproposedtoinvolvering-openingofaboundepoxidesubstratebythecar- bonate end group of the growing polymer chain. The more detailed path- waysforproductionofthethermodynamicallystablefive-memberedcyclic carbonateareillustratedinScheme1.2.Inourearlystudy,weclearlydem- onstrated that employingthe(salen)CrCl catalyst system, the selectivityfor