Deoxygenation of biobased molecules by decarboxylation and decarbonylation–a review on the ...

20 Pages·2015·0.8 MB·English

Green Chemistry
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wnloCom for use. Deoxygenation is an important method of defunctionalisation. While thermal deoxygenation is
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es moleculesanddiscusstheirlimitationsandadvantages.Wemainlyfocusontheactivityofthecatalysts
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Ac Received5thJanuary2015, andfindthereisastrongcorrelationbetweenspecificactivity(turnoverfrequency)andtemperaturefor
n Accepted18thMarch2015
e metalbasedcatalysts(homogeneousorheterogeneous).Thusoneisnotmoreactivethantheotherat
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O DOI:10.1039/c5gc00023h thesametemperature.Alternatively,enzymeshaveahigherturnoverfrequencybutdrawbacks(lowvolu-
www.rsc.org/greenchem metricproductivity)shouldbeovercome.
1. Introduction feedstocks satisfy our need for the production of chemicals
andmaterials.
Inordertoensureourplanetremainshabitableforfuturegen- Biomass is extremely diverse in its composition, which
erations and to satisfy our needs for chemicals, fuels and necessitatesthe development of a biorefinery. A biorefinery is
energy, the use of renewable resources has become essential. definedas“afacilitythatintegratesbiomassconversionprocesses
ThishasmotivatedtheEuropeanCommissiontostriveforthe and equipment to produce fuels, power, and chemicals from
use of 20% by usage of renewable energy sources, 20% biomass. The biorefinery concept is analogous to today’s pet-
reduction in CO emission compared to 1990, and 20% roleumrefineries,whichproducemultiplefuelsandproductsfrom
2
increase in energy efficiency, by 2020.1 In order to achieve petroleum”.6 One example of this in practice can be seen by
theseambitionsalternativeenergyandfuelsourceshavebeen looking into current-technology for bioethanol production,
developed, such as solar,2 geothermal,3 hydropower4 and whereasingleplant7producesnotonlyethanol,butalsoelec-
biofuel production from biomass.5 While a number of such tricity and dried distillers grains and solubles (DDGS), which
developmentsarepromisingforenergysupplies,onlybiomass issoldasanimalfeed.
The development of chemical production from biomass
using fermentation is already becoming economically and
industrially viable. Products such as 3-hydroxypropionic acid
andlacticacid(fortheproductionofacrylicacid)arecurrently
BiobasedChemistryandTechnology,WageningenUniversity,BornseWeilanden9,
6708WGWageningen,TheNetherlands.E-mail:[email protected] emergingontothemarket,8andevenhydrocarbon-basedfuels
Thisjournalis©TheRoyalSocietyofChemistry2015 GreenChem.,2015,17,3231–3250 | 3231
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Perspective GreenChemistry
are being produced fermentatively.9 The feedstock of choice use of enzymes is considered one of the most expensive com-
for fermentation is glucose or glucose containing substrates ponentsofbiomassconversion.10,25
such as starch or, more recently, cellulose.10 Recent research Chemo-catalytic conversion can be used to produce chemi-
has focused on deriving these from sustainable secondary cals with high volumetric turnovers and are widely used in
e.
nc materialstreamse.g.secondgenerationlignocellulosicfermen- current chemical synthesis techniques. For the conversion of
e
Lic tation,11 utilising cornstover or wood from otherwise un- biomass current examples include high intensity techniques
d productive land12–14 or chemical and thermal reclamation like gasification of biomass to form bio-syngas.26–28 This can
e
ort from waste such as slaughterhouse effluents or household be fed into Fischer–Tropsch reactors to produce waxes and
p
Un garbage.15,16 paraffinsforfuels.29–31Pyrolysisofbiomasssuchaswoodchips
3.0 So far, a significant focus has been on fermentative tech- allows for the production of bio-oil,32 lignin depolymerisation
M. cial niquesforbio-basedchemicalproductionduetolowtempera- in supercritical carbon dioxide allows for the production of
Amer ture selective conversions and the ability for molecules to BTX-like aromatics for the chemicals industry.33 Lower temp-
4 m
5:1Co undergo various transformations in one processing step. erature chemical conversions are also common, such as the
1:0on However, fermentation processes can have low substrate/ productionofisosorbide,amonomerandplasticisingagent,34
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ss Article. Published on 09 April This article is licensed under a Haastvpaliheipnraptyeleprydaedtlscrirpaicceetocrnieusqalovy2ldlutedl0saiulioiuryrruslneecaspirdttsseneeire.odona2t1en2dc0ot,irit2unfeoiao3ocsnrfbetnFeeigosonsofblriofzliuneonryecciggmnxohglmiaesgceiemeraneseail,dennplfiworivaltcaeryfeanilo,snstfoarthikeeiorfrgeisemnm,taeeovgtxneeweerazrenpdrmhiydyotcmeafuwpiroptmcelaidrreottopeaintscdrsohi.sepnure,csTtecgioaarphtlcnnnseteaativdfndpeeriharnpoαnisbsml-gaiaiieeohcnnmsanrdt1utasi9ysusioecloesamleinedtssamrceenititora2indiocs1fl- bnftdcrpteaiehiaeaorgqoserlnmei-uaimbsrtieaeiaoorivntecsfffietmtaeoloeaodlynrstexis,lsnmoyouigatnwnosopenp,clnopdfelpuafulcyonnddeuprdrtcil‘trhondetuoispacrgondornsntiuudpotoaicfde-lerlitmoeinossftxr)m’yaoyotkgcormitleeoeo5-pndmp3gplear%almrprotuociiadcoeavdrtoeuminueondsc.dceetet3Aan,ets4ionntwen%soxdbhefi.i(sxetoipathardTimremneseohigntadpimhssctuliesupeicc.lirraamstoDorslrefdadenhGttuscuohtasaicebivrtspcmsebbtueoisoarcsrfxcrrrofyoettekrmhhlenmneaeeett---
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c starting materials. However, the high selectivity of enzymes energy in a simple transformation. Decarboxylase enzymes
A
n can be problematic when using racemic feedstocks, as up to comprise of 80 members, mostly amino acid decarboxylases.
e
Op 50% of the starting material may not be transformed.24 The Examples of using these enzymes have been investigated44–46
GwenDawesis aPhDstudentat Elinor Scott is Assistant Pro-
Wageningen University, in the fessor at Wageningen University
chair group Biobased Chemistry at the chair group of Biobased
and Technology. She obtained ChemistryandTechnology.Since
her Bachelors and Masters 1997 she has been concerned
degree at the University of Cam- with the development of econ-
bridge, UK. She has worked on omically and ecologically attrac-
thefoldingofspectrinattheUni- tive conversion routes and
versity of Cambridge, and inves- processes of biomass to indus-
tigating drug delivery from trialchemicals.Sheobtainedher
implantabledevicesatTUDelft. PhDin ChemistryatHeriot-Watt
University. Following positions
GwenJS.Dawes ElinorL.Scott as Post-Doctoral researcher in
the field of polymerchemistryat
theUniversityofStrathclyde(1994–1995)andHeriot-WattUniver-
sity(1995–1996),shemovedtotheNetherlandswheresheworked
asanindustrialPost-DoctoralpolymerscientistatDSMandlater
asascientistatATOlookingintobiomassconversions.
3232 | GreenChem.,2015,17,3231–3250 Thisjournalis©TheRoyalSocietyofChemistry2015
View Article Online
GreenChemistry Perspective
insignificantdetailonthetransformationofbiomass,25,47but which typically come from plant sources, and typically have
reviewsonchemocatalyticdefunctionalisationarelessprolific. lower melting points due to their more bulky structures. The
Defunctionalisation by removing oxygen can be performed distribution of these molecules from different sources is
using hydrodeoxygenation, decarboxylation and decarbonyla- covered in other works.40 As these molecules are very rich in
e.
nc tion. Hydrodeoxygenation has been reviewed previously for carbon and hydrogen and otherwise poor in functional
e
Lic biobased feedstocks and will be left out of the current groups, they are attractive for the formation of fuels and oils.
d review.48 In our review we will focus on the decarboxylation Global production scale is around 6.5 billion litres, as per
e
ort and decarbonylation transformations of bio-based molecules 2006.49Currenttransformationmethodsforfattyacidsinvolve
p
n
U such as a variety of aromatic and aliphatic molecules, includ- the production of fatty acid methyl esters (FAMEs) by trans-
0
3. ing amino acids, into industrially relevant compounds using esterification from glycerol, in order to produce bio-diesel, a
M. cial hetero-,homo-andbio-catalysis.Itwillattempttodrawparal- fuel product that can supplement diesel fuels.50 Diesel typi-
Amer lels between the use of a specific catalytic systems on various callycomprisesofaliphatichydrocarbonsofbetween9and28
4 m
5:1Co substrates,andalso between typesof conversion,showingthe carbon constituents, with an aim to contain as little aromatic
1:0on resultingactivity,selectivity’s,andwhereappropriate,mechan- residuesaspossibleinordertopreventcarcinogeniceffects.51
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ss Article. Published on 09 April This article is licensed under a lufbolcsIaaanoorestrtiymuitdgtobhyahi)pneny.laeloadaycTtnnrlipoholdecyreolasnoeyysilsnstlkahes,easraondriepnowsecatefaetnsltostmyot.otapoifhFfclofiosaachrc,ittatmaeltrlf)sytdil,aauyaatflactctrycpoyylehtigrliedaggeacsacllsefyyisqsa,adccetureeasttdeahyrrnaionocddoarltoseuceibematistaidyn,ebmdosisewlmfeesoarohtsannitefeveoldlreeryssedudligofilsnnovlutfyedhukrarcroeacnrse(ermegIdr)gaeseoonssil(npl.a,edooll.Taaentngisnhcln.ga,,adetttwsruiractbmerlhhl(eowoeaiauxc.waairsgynhesst-., tctbfTtooooolfehorefbufcuHonaoedsdrte,nitmfeaeyopavffvsecoayaedeunicllcnmesktitidcetfaioeaudvsnbntreeaebyfoalolsiolnsn1rixod0nhcymrcioaloetaaovonasltledrnekivd1oeleeyb.5enrrn5etry3eeci°ernlnsCeTatigoamr,hwkscpdehn,atmyiletiosaoeccauawnnhsrilce.ntns5htacoto4oatsaioaiTnilsrnnssuheabgmifflubnelttoeyshothu,rwoevteschefaeturdeahdoordebermxusarieylsiodsngirepteaeetfycn-dunoirafneeforiiplsnbsl.rseerocuoaratrxhebrpdeycqsiealhstutarsietteitfhitiruueoreaotaesndesfl-.
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cc two broad classes of fatty acid: saturated fatty acids such as acetate.55 However, as this reaction requires stoichiometric
A
n stearic acid (C H O ) and palmitic acid (C H O ) which amountsoflead,itisnotcatalyticandwillnotbecoveredany
e 18 36 2 16 32 2
p
O typically come from animal fats, and unsaturated fatty acids further.Theuseofsilver(I)saltsandsodiumperoxydisulphate
such as oleic acid (C H O ) and linoleic acid (C H O ) to produce alkenes by oxidative decarboxylation has been
18 34 2 18 32 2
JohanSandersisProfessorEmer-
Jérôme Le Nôtre is a Post-doc- itus of Valorisation of Plant Pro-
toral researcher in the chair duction Chains at Wageningen
group of Biobased Chemistry University. His work focuses on
and Technology, Wageningen reducingtheCO productionina
2
University working on catalytic cost effective way using chem-
conversions of biomass to bulk istry, fermentation and biorefi-
chemicals. He obtained his PhD neries at a large, as well as at
in 2002 from the University of small scale, to enable optimal
Rennes for research on ruthe- application of all plant com-
nium metathesis reactions. After ponents. From 1977 to 1993 he
performingpost-doctoralworkat worked at Gist Brocades,
Utrecht University and at the JohanP.M.Sanders working on various projects in
JérômeLeNôtre University of Bath he joined the the field of enzyme research; he
group Biobased Chemistry and became Associate Director of Food Research. From 1993 to
Technology. 2001 he worked at AVEBE as R&D Director focusing on the enzy-
maticandgeneticmodificationofstarch.
Thisjournalis©TheRoyalSocietyofChemistry2015 GreenChem.,2015,17,3231–3250 | 3233
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Perspective GreenChemistry
observed previously.56,57 In these reactions the driving force
comesfromtheperoxydisulphateion,whichproducessilver(II)
ions in solution. These ions are able to selectively decarboxy-
late fatty acids.58 The peroxydisulphate ion is a strong oxidis-
e.
nc ing agent itself that can be used to oxidise several organic
e
Lic speciessuchasformicacidandsmallalcoholsinwater,butis
d unselective.59 The mechanism for this reaction has been
e
ort expanded upon in further work.60 Drawing together these
p
n
U references,weseethatthisreactionproceedsviatheformation
0
3. ofasilver(II)ioninsolutionafterreactionwiththeperoxydisul-
M. cial phateasshowninFig.1.
Amer Thisreactionproceedsviatheformationofasilver–carboxy-
4 m
5:1Co late complex B, then radical initiation to form an unstable
1:0on carboxyl radical. This subsequently degrades into an alkyl
3 N
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2015. DownloCreative Com ciiaosanmnpdadibanilseplaorowolfaptooecoxrrtinidwocionezrnianktt.gir6oa1ntwiToawhnteaisrsoiftcsootanhodfexivsryaemgneetsnadhgoaeautoslurdtosho:bemsecilovmtreerrame(iIcnIptI)teamriiaonetnuecsdhreaa,inr5ne8- oFixgid.a1tivReedaecctaiornbsoxcyolanttiroonll.ing silver(II) and copper(II) mediated fattyacid
ss Article. Published on 09 April This article is licensed under a pboaiisocnntolrfreakgsdipCtmtypeepeol,rdraeaxrDordriattpd(yodoIaoIeai)nakbfftrcilstdeaeveciaeloecotElpotnthheiscavpeolecieltrlffimruosloaytrcoicttsHneediheeatpe,idondtscHeiwcaofrtr,yorheenabrrtapehhmmotcriioendetgiiFlyhnooyrXlnc.ieai6nfcna,t2r=uegcoaF,AtrmdsiO.iasotgdTenHn.ttiphdhth1.i.iteeo,soNAprnserresotafeo.naroladtbWmarhccuibmteloiaciiltoolesehlcismnrynoda,tthgpoliwhtknhpeleiaeeateesanctprauidfe(asoonIldsIthenr)dhimoGtwiBoiawo,oafla6nnltn3wyoitohwaototinooessrf- saalsaaeatcptttlipireduRoarcsrnecota.cti6atvie4oecvinfhdetIynt.,slfyet(tooh,vhreleseeriailauclcvlkase,aessrenraonitecofuisitfrfnroausaotfartelettemdhuiwcera(a,raxstst.ueee5duslai0esrafieadmocdtiftcoayar,lnes%adalcaiginadpectonasalc,lttemosaiitmcliiy,wstspitacclliseofnaotnsceorhsildciedodo)nweencianrcvane)erdtdbrhfsolaauiexottnstynasy--
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cc itself reduced by these actions, it must be regenerated, using whenusingpalmiticacidasasubstrate.Thisreactionwasper-
A
n more peroxydisulphate. In terms of a Green Chemistry formed at 78 °C for 20 min, in water–acetonitrile 5:9 in the
e
Op presence of silver nitrate and sodium peroxydisulphate. The
details and yields can be seen in Table 1. The other side pro-
ducts for this reaction are not characterised, but a small frac-
Harry Bitter is Professor of the tion of 1-pentadecenol and pentadecene were observed in the
group Biobased Chemistry and reaction mixture. By using thermogravimetric analysis, as
Technology at Wageningen Uni- much as 35 mol% of the material is noticed at 200–500 °C,
versity. His group focuses on the and up to 10 mol% from 500–800 °C, implying that a signifi-
sustainable production of bulk cant amount of polymerisation is occurring in the radical-
chemicals and fuels from based reaction. With the addition of copper(II) sulphate,
biomass by an integrated 37 mol% 1-alkene and 22mol% 1-alkanol was producedfrom
approach. The group motto is
TIPTOP chemistry and technol-
ogy: Turning variable InPut into
Table1 Decarboxylationofpalmiticacidbysilverandcoppersaltswith
TailoredOutPut,oneofthegreat
sodiumperoxydisulphatea
challenges in biomass conver-
JohannesH.Bitter sion.Hestudiedchemistryatthe AgNO3 CuSO4 Na2S2O8 Conversion% A B C
Radboud University and
1 — 0.5 80 <1 19.6 <1
obtained his PhD at the University of Twente. He continued 1 — 2.5 97 <1 49.9 <1
working in the field of heterogeneous catalysis at Utrecht Univer- 1 1 0.5 93 12.3 <1 7.4
sity, focusing on the use of spectroscopy in catalysis. During the 1 1 2.5 99 35.4 2.2 16.5
last years he has focused on the application of catalysis in aReaction conditions: Acetonitrile:H O, 9:5, 20 min, 78 °C A:
2
biomassconversionsandtheuseofcarbon-basedcatalysts. pentadecane,B:1-pentadecene,C:1-pentadecanol.
3234 | GreenChem.,2015,17,3231–3250 Thisjournalis©TheRoyalSocietyofChemistry2015
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GreenChemistry Perspective
palmiticacid.Theauthorsnotethattheterminalalkeneisnot Besidessilversalts,copper(I)hasalsobeenshowntoactas
the only product of this reaction. As the copper(II) salt can a catalyst for the decarboxylation of compounds such as cin-
coordinatewithalkenes,atthereactiontemperatureof78°Cit namicacid.72Here,20mol%ofcopper(I)bromidewasused,in
allows foranisomerisationto occur,moving thedouble bond additionto240°Cand2equivalentsof1,8-diazabicyclo[5.4.0]-
nce. along the molecule, and thus affecting the purity of the final undec-7-ene (DBU) for a 30 minute period to produce styrene
e
Lic product, however the overall selectivity for monomeric at75%yield.
ed products was increased. When using unsaturated fatty acids Silver(II)andperoxydisulphatemixturescanalsobeusedto
ort the problem of incomplete mass balance becomes more decarboxylateaminoacids.73Aminoacidscouldbeaninterest-
p
n
U significantduetothepresenceofreactivedoublebondsinthe ing feedstock for the formation of chemicals, as several are
3.0 molecule, increasing the probability of polymerisation, structurallysimilartocurrentindustrialchemicals.74Withthe
M. cial however 10–35% of the desired alkane or alkene was useofdecarboxylationreactionsanumberofrelevantproducts
4 Ammer obtained. Other authors have further investigated and could be obtained. At catalytic concentrations of silver(II) in
5:1Co reviewed the mechanistic pathways in the deoxygenation of water they successfully showed that a radical mechanism
1:0on vegetableoils.65 occurs,showninFig.2.Interestingly,theyshowthatathigher
3 N
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wnloCom benzoin resin. The latter can be derived from the bark of the were to be performed in a more selective approach it would
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ss Article. Published on 09 April This article is licensed under a smyegsLbsettuirirartgoteibhunetnwshcefatielitirdnoynauq,odlguridpienessaosetonenpfduvtddoleseprylrcusrytbyeccohcmyrohduoilnebuostfrvhweciahebsdiesnraeitocvgdmeiomendvnlaaaiaargcrimnsonkenlisomentoli-olwtndrti,arceeoatcprlittaacdirhiavnrooeeecgcdntdirceoadusolimc,yclanotrpotimaldyvaaonrluiitputdnereyotnri.hnuodtAesigxnosnylysdtrgpefpisctrenlr.hlooann6agi8mnuanasictlttHtdseirvbdoeoeabivwviloaceelyiemsierr,dvoywlaeiambg,rssesn,asalbuioninntunbiiwdogcst-.
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Acc phenol.33,69 Silver(I) has been shown to act as an efficient de-
n carboxylating agent of aryl carboxylates such as ortho-anisic
e
p
O acid, producing 98 mol% anisole in the presence of 10 mol%
silver(I) acetate and 15 mol% potassium carbonate in
N-methylpyrrolidone (NMP) at 120 °C for 16 hours, as shown
inTable2.Theyalsoshowedthatsilver(I)candecreasetheacti-
vation energy for the decarboxylation of 2-fluorobenzoic acid
to as little as 29 kcal mol−1 when NMP is used as a
solvent.70,71
Fig.2 Aminoaciddecarboxylationbysilver(II).
Table2 Decarboxylationofanisicacidtoanisolea
Catalyst Amountcatalyst(mol%) Ligandb Additivec Solvent Temp(°C) Yield(mol%)
Ag O 5 Phend — NMP/quine 170 22
2
Ag O 5 Phend — NMP 170 85
2
Ag O 5 Phend — NMP 120 60
2
AgOTf 10 Phend — NMP 120 0
AgOAc 10 Phend — NMP 120 70
AgOAc 10 PPh — NMP 120 0
3
AgOAc 10 — — NMP 120 24
AgOAc 10 — K CO NMP 120 98
2 3
AgOAc 10 — K CO NMP 80 60
2 3
aReactionconditions:16h.b10mol%.c15mol%.d1,10phenanthroline.eQuinolone.
Thisjournalis©TheRoyalSocietyofChemistry2015 GreenChem.,2015,17,3231–3250 | 3235
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market scale of about 0.3 million tons per year.75 Levulinic solution of citric acid and sodium hydrogen phosphate, the
acidisacompoundformedbythehydrationofhydroxymethyl- rate of reaction relies upon the availability of carboxylate
furfural (HMF), which itself is formed by the dehydration of groups for the silver(I) ions to coordinate to.83 Thus, a sharp
glucose (or fructose) in the presence of (Lewis or Brønsted) peak of activity occurs at pH 4 and above, resulting in an
nce. acidcatalysts.76ThesestepsareshowninFig.3.HMFisaplat- increasefromalmost0to30%yieldofbutanone,withthecon-
e
Lic formchemicalinitsownright,39beingcapableofbeingtrans- versionoflevulinicacidchangingfrom<5%tonearly80%.At
d formed into several other industrially relevant compounds a pH lower than 4, they report no butanone production and
e
ort including furandicarboxylic acid (FDCA) or caprolactam.77 thatthemainproductisacetone.Thisisreportedtobeaside
p
Un HMF has also been shown to undergo selective decarbonyla- product of their buffer, citric acid, degrading in the reaction
3.0 tion to furfural alcohol using Ir based catalysts.78 Fructose is conditionsinsteadoflevulinicacid.Thebestyieldofbutanone
M. cial either found in nature as a monosaccharide and is signifi- was 43% after 30 minutes at 140 °C in an autoclave, at a
Amer cantlymoreactivethanglucosefortheformationofHMFand selectivity of just over 60%. They also report production of
5:14 Com levulinic acid.79 The reaction from glucose is considered to methyl vinyl ketone when copper(I) was used in place of
1:0on proceed via the transformation into fructose, but is shown in silver(I),butnoclearyieldanalysiswasundertaken.
3 N
1/202ution- tshuegadriasogruarmcesasangdlutchoussehisassoauwrciedderfraopmplibcaottihons.taLrecvhulainndiccaacnide 2.2. Palladiumdecarbonylation
1b
ded on 1/ons Attri hoofrascfhutheelmeopicxoaytglesennstuiaatcleh)t,oa80sbd2e-iamphpeeltanhtoyflolitrcemtarcamihdoyld(earcounfluoervaefonlrm(tahonenoopvmreoledsru)o,cl8vt1ieononrt Csuacrhboansyliantitohnerpeeatcroticohnesmaircealresayndtihlyesuisseodfianceitnicduasctirdiaalmscoanlgesst,
wnloaComm used in the form of levulinic esters as fuel.82 However, orig- coathtaelryss.t84inThsisolpurtoiocnes.sBreefloierseutphoisnwthaesptrheesenMcoenosfanantoIrp(CroOc)e2sIs2
ublished on 09 April 2015. Doe is licensed under a Creative ppiiynseehhaaroerllsskdypgfha.tr7hsao6etmteIhniaemantehpdlsoaetwscidomtde$oaci0ftua.e1mrtdb0ho/icpksxoegysrm−ltoa1toxoiyulofedpncpiusrtouoloefldpalumhecvasatuutiyeolbinnbisntieahcanasantoscimaiardliqlesyuwweenhhiotiahiugtnhssdeirblirevumce$fferi1nne(I0rt)- bsbmmcthuaaoaeargsnFbtrneaaykuodrllersarnshdf,t.yu8iloolo7ymradnnatiila,uohiaRmninistghlylha(oeaCecraxtOrsmyiitvr)lo2iiaoadtIsjyf2coie.utfriumvHcarpianft.ort8uydwao6rldeayHacuvls,eoroicsaprmwt.,ba8ep5filivnrltaaeosordrPmes,iaaeduwlc,lmttahhiodvte-eorbiintiuaygdmsiiteoneih(sdtcaIhIyot)cdilemenarrstagaesaltsslityfooratrsanotottnsmrsdsaosheicfhtoctitoiaowhCvwrnees5-
s Article. P This articl hthheeemmdiiccreeyllllwuuellooigssheeticsfoombrephtwoanredeewnnto5oo%dfslf.i8og9rnBsooacgfetalwlsuosleoodsfesro.8am8ndTshuuegpaartmcoaon2u5en%atlsoooff
ces contains between 26 and 30% pentosan sugars by weight,90
c
A andsomefoodstuffby-productssuchascornhuskscontainup
n
pe to28wt%xylose.91Giventhatthesematerialswouldotherwise
O
be used for theircaloric value, these feedstocks are preferable
towood in an industrial capacity. Due to the low overall yield
involvedwiththeproductionoffurfuralatlargescale,theesti-
matedmarketpriceoffurfuralisaround1700$perton.88The
decarbonylation of furfural can be used to produce furan, an
intermediate in the production of tetrahydrofuran (THF), a
widelyusedsolvent (Fig.4).Furfuralisalsoapromisinginter-
mediate for the synthesis of chemicals or fuel applications.
Examples include methyl tetrahydrofuran and ethylfurfuryl
etherasfueloxygenates,aswellascomplexaldolcondensation
routestoC andC moleculeswhichcanbehydrogenatedto
10 15
formbranchedalkanes.82
Shown in Fig. 5 is the mechanism elucidated for the
decarbonylation of fatty acids by palladium(II)-based homo-
Fig.3 Formationof butanone fromglucose via hydroxymethylfurfural
andlevulinicacid. Fig.4 Formationoftetrahydrofuran(THF)viafurfuralfromxylose.
3236 | GreenChem.,2015,17,3231–3250 Thisjournalis©TheRoyalSocietyofChemistry2015
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GreenChemistry Perspective
ofaceticanhydrideproducedcomparableresults.95Theuseof
stearic acid anhydride as a substrate also proceeded to 94%
yield with a production of 93% stearic acid, indicating the
addition of an auxiliary anhydride may not be necessary.
e.
nc Maetani et al. also showed that palladium(II) is not necessary
e
Lic either, showing a successful decarbonylation occurring with
ed iron(II)chlorideasacatalyst.96
ort One otherconclusion from Gooßens work isthat DPEPhos
p
n
U isneededasaligandforPdCl toimproveactivityandselecti-
0 2
3. vity in the transformation of phenylbutanoic acid, as the use
M. cial of other phosphorus-based ligands allows for too-rapid iso-
Amer merisationandlossofselectivity.Bythissametransformation
4 m
5:1Co methoditwasshownthatpalmitic acidcouldbe transformed
1:0on into 1-pentadecene with 64% yield after 16 h reaction time
3 N
1/202ution- pwyitrhim3idminooln%ec(aDtaMlyPsUt)i,ns1e,e3-DTaimbleeth3y.l-3D,P4E,5P,6h-otestriashyndorto-a2l(w1aHy)s-
1b
ded on 1/ons Attri rdheeyqdcuaroirrbxeoydsntyywlraehtneioenn, oiosrofomhfeysrduirsocacctiiinonnincamiasciicdnoamtciodanno(deiesstssecurrei,btoesduaccirhnyli3ac.s5a)tchitdoe
am
ss Article. Published on 09 April 2015. Downlo This article is licensed under a Creative Com gdbGgFfoioeyrgorinum.odoe5sßeatot.hefi9uoanPe3sns,ar9he.slc4lt.aiaodIatTtanilu.lhimysswissh-thtcsoheam,wotnaaueeslydcgasphhnetrathdoneaptdnihtoseoatmcshltaeerdedbisresobtecneyaarryceGrlatibiitsonoiooofnnsonßuyretoclbaanfesktdftieeaiotttsnutbayptyleapl.a9cdrt2ciohdeafcseoneivrneddiadteaehsatnxnaetvhieailayanndntdarhthilhedoaydeet-- satstslpulifeainhiotthtsrpgoardrtdaooainenmsinnbiwtnuurccoglc.adamscee91oetth7sm9it%nni,ioh%nTstdhntiagohhnitti.(atfeoge2itilItshrofhm5inhtmcsen0chteoooaathsirenmes°ntcoessramtCcoaleeeillemfmlyqaurpirsinosusearaspitifelarilatloaeskrahaletternhffetihcxeodpuntoeririFndrrsewceotoeetartoslnshsdoai(ci.vCgswafatuaeaiT,aOcncontnnhhhhta)nad,(d1iieiesCegls1swtvhaifldhuD0tenoi)shootc2Pslhg°hauluaecsEoCotblgoaImwPeoa)rhlnmt.cheCsd-h9out8obeliedbiyp(vtsneCeUihoimcetrOnwesianylatnyuduhsd)dtof(eobsceorePtschrsksrrhaPatuhfreiphincmooseotssrhu3erfwoeoma)oetm2bdtceosa,hruyctdufpetet-iochchparsecpfhueiacriorehsrnspottrmaciPerdtaotueplnPiptouenfamohayhoserccsnllees3rrt----,
e
c
c formationofananhydride,whichthenallowsthecoordination butanoicacid.
A
en of the palladium(II) salt. The anhydride is cleaved to produce Significant work has been performed by the group of
p
O anacylanion,whichthencoordinatedtothepalladiumatom. Gooßen et al. into the use of palladium(II) based catalysts as
As the product of this reaction is an alkene, isomerisation of centres for aryl carboxylate decarboxylation, particularly for
the double bond is an issue, but it can be eliminated by the coupling reactions (Fig. 6).99,100 For Heck-type coupling reac-
useofcorrectconditionsandligands. tions, the mechanism proceeds via a reductive elimination in
Originally,theuseofbis(2-diphenylphosphinophenyl)ether order to remove carbon dioxide, so an oxidant is required to
(DPEPhos)ligandsand125°Cwasselectedasameansoflim- drive the reaction. The original work on this field uses silver
itingtheproductstoonly1-alkenes.Itwasshownthattheuse nitrate as an oxidant,101 but this can be replaced with oxygen
of pivalic anhydride can produce the required anhydride to as the electron acceptor,102 without significant impact on
promote decarbonylation, but further research shows the use yields or selectivity. For decarboxylative cross coupling, the
Table3 DecarbonylationoffattyacidsbyPdorFesaltsandanhydrides
FattyacidR= AnhydrideR′= Catalyst Ligand Solvent Yield1-alkene(mol%) Yieldotheralkene(mol%)
PhCH CH tBua PdCl DPE-Phos NMP 70 <2
2 2 2
n-C H tBua PdCl DPE-Phos DMPU 64 —
13 27 2
PhCH CH Meb FeCl DPPPentc — 56 2
2 2 2
n-C H Meb FeCl DPPPentc — 65 6
13 27 2
n-C H n-C H b FeCl DPPPentc — 94 —
15 31 17 35 2
a2eq.Anhydride,3mol%cat.9mol%ligand,110°C,16h.b10mol%cat.20mol%ligand,1eq.KI,1eq.anhydride,240°C,3h,CO(20atm).
c1,5-Bis(diphenylphosphino)pentane.
Thisjournalis©TheRoyalSocietyofChemistry2015 GreenChem.,2015,17,3231–3250 | 3237
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Perspective GreenChemistry
e.
c
n
e
c
Li
d
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ort
p
n
U
0
3.
M. cial
Amer
4 m
1
5:Co
1:0on
3 N
1/202ution-
1b
ded on 1/ons Attri Fig.7 RadicalrearrangementofHenkelreactionproducts.
am
wnloCom
April 2015. Doder a Creative FCiug(.I)6,AgD(Ie))c.arboxylative coupling with Pd(II) and a second metal (M = sttheyrseetIeptpmhirsothdweauvolecarntttseht,u.1mab1l0eleynnztdeionisnepi,rnoagpnohdretrtiheoenthattahetesrtemarneopddhyrtnehaaamrlriicacnagpceirdosdctuoacntfoa1rl,sm4o-
s Article. Published on 09 This article is licensed un lalhpsByaunraesdibcdltmii,asudseucameuqosrsbyeup.,11sep0m0pen34eaqetrloTu(clIatehh)rhdeneaoeditrnurrleuyimsacsttmtrihr(ilyIavveIl)eeniyscris(sacfeIbe)ralnbyrinimoosttthxrbiuayneaelnsaarvestcteeidmeosorsuuynet,l1pot,at0alic5enlpstadhigortvoiroeaowmwrandiynrtoelhyotclgefabrggroaedrrbluoroeoyoupcuwlxapspylrsislobgaivnofatperixnrooryodFnmltdaisogucti.apaacontraen6ayddll--,. OdlbfmtooheatwreehtmniedeoDdterenarditmiebivolbyoesenyfd–tahAdrfbtoloidromdimooesmremairsitinoraizosesbcaatasluthtcu-iidtetoodeiernonnern.ebio1tv1i1hfe1o5ode2imfsTooaomhxbxsryeiusudlsetcdeaesnotenoeinahoue.ri1y,nrec1dcp1eroaarasotfctXtdierspdyaduualceccrtaenahibnvd-eicedoayb-smpciyesartvoegonhinblcayueuelcae,stt1ohalsn1ssene4eoesoaoff.fn1eobxo1ridle3r---
cces byC–Hactivation.106 Thisreactionisusefulfortheutilisation the production of ‘drop-in’ compounds from bio-based
A origins,howevertheyarebeyondthescopeofthisreview.
n of benzoic acid derivatives and producing compounds for azo
pe Analogous to the Henkel route to terephthalic acid
O dyesorothercolouredcompounds.Inaddition,theabilityfor
this to activate C–H aryl bonds gives it added purpose in the from benzoic acid, this reaction can be applied to furoic
acid, derivable from furfural to form 2,5-furandicarboxylic
utilisationoflignin-derivedcompounds.
acid (FDCA).116,117 Pan et al. showed an 86% selectivity for
2.3. Henkelreaction FDCA when this reaction was performed at 250 °C under 38
bar CO for 3 hours with zinc chloride as a catalyst, see
Henkel decarboxylation can be used to disproportionate the 2
Fig. 8.118 FDCA, when used in place of terephthalic acid to
presence of carboxyl groups on aromatic molecules. Research
produce poly(ethylene furandicarboxylic acid) (PEF) can have
onthisreactionwasoriginallyperformedfortheproductionof
similar physical properties to PET.119 FDCA can also be pro-
terephthalate from benzoate, discovered in 1952 by Henkel et
duced by the oxidation of 5-hydroxymethylfurfural, shown in
Cie.107toworkovercadmiumsaltsat500°C.Terephthalicacid
section 2.1 to be able to be obtained from glucose by de-
is used in the production of poly(ethylene terephthalate)
hydration. This oxidation is reported to occur by the use of
(PET), a plastic used for its controllable crystallinity, trans-
stoichiometric potassium permanganate,120 but recently has
parency and low permeability of gases, and has a global pro-
duction of above 40 million tons per year.108 Unlike the
mechanism for silver-catalysed decarboxylation, this reaction
proceeds via two-electron abstraction of CO , and the use of
2
cadmium(II) allows for proton abstraction, as shown diagram-
maticallyinFig.7.Itwouldappearthatthecatalystisrequired
for the selectivity for thermodynamic products, as Henkel-like
activity has been observed in the pyrolysis of coal products at
425 °C, but the main product observed is phthalic acid rather
than terephthalic acid.109 The mix of products in the reaction Fig.8 Henkelreactionperformedonfuroicacid.
3238 | GreenChem.,2015,17,3231–3250 Thisjournalis©TheRoyalSocietyofChemistry2015
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GreenChemistry Perspective
beenfoundtooccurreadilywiththeuseofgoldnanoparticles occurring on the anodic side of a reaction vessel, where oxi-
onceriumoxidesupports,givingasmuchas99mol%selecti- dations take place. Mechanistically, this reaction is disagreed
vityat130°Cinwaterwithairasanoxidant.121Onebenefitof uponinitsbasicelements.124–126Thereactionhoweverisgen-
theHenkelreactionisthatitproducesfuranasasideproduct, erallyagreedtoproceedviatheformationofacarboxylradical
e.
nc which itself can be hydrogenated to tetrahydrofuran or 1.4- and subsequent decarboxylation into an alkyl radical.
Lice butanediol. This was proposed by Pan et al. as a carbon- Sufficiently stable radicals at this step can go on to form n-1
d efficient means of producing polymers from furfural, using length alkanes, alkenes or alcohols, but with the correct sub-
e
ort 1,4-butanediol and FDCA as precursors to produce poly(butyl strate a radical coupling reaction can occur, creating 2n–2
p
n
U furandicarboxylic acid), thus utilising 100% of the input lengthcarbonbackbones.Thisreactioncanbedirectedbythe
3.0 carbon.118 The highest selectivity disproportionation was per- use of pressure,127 in the case of pentanoic acid, 1.1 MPawas
M. cial formedinasealedreactorat250°C,using0.1gzincchloride sufficient to boost selectivity for n-octane from 42% to 63%
Amer asacatalystpergramofsubstrate,andinsupercriticalcarbon (scheme ii and iii, Fig. 9). As this reaction was originally
4 m
5:1Co dioxide. They report no activity when other metals such as observed for the formation of ethane from acetic acid, appli-
1:0on cadmium, copper or nickel, were used, although a small cationsofthisreactionarecentredaroundthedecarboxylative
1/2023 ution-N ashmoowunthtaotfccholnorviedresioionnwsaasreobasreerqvuedirefdorcloaunnthtearniuomn,.oTbhseeyrvailnsog Rcoeucepnlitnwgoorfkfahtatysabceidens,suhpogwrandtinogbtehaebmletotolounsgeetrhcihsatiencsh.1n2i8q,1u2e9
1b
ded on 1/ons Attri noactivitywhenzincoxideorzincacetatewereusedinstead. sfdohurocwtciroaonsysioeflcdoauodpfipl7ion8ngmitnroiillt%er,i,ledinetrdeiivrcemadtiinnfargotemtdhegfrslaueglteamcmteiinvcittsyacoiinfdt.1thh3i0seTrpehareocy--
am 2.4. Kolbereaction
wnloCom The Kolbe reaction is a means of coupling two carbon chains tiontocarboxylatecomponents.Adiponitrilehasaglobalscale
2015. DoCreative teolegcettrhoecrhewmiitchalsruebascetiqounenist ionxtiedreastitvinegdferocamrboaxytelacthionno.logTihcaisl opoffronadyruolocuninn-d6g,61h.(i5sgchmh-peilmuliroeitniy),t1oF,n6ign.he9se),x.1aa3nn1eddiiasmseinleectfioverlythheydprroogdeuncatitoend
April der a preoqinuitrionfgvnieowaausxitlihaeryocxoidmaptioounnidsscaanrrdietdhuosu,tinatthtehoerye,leimctrpordoev-,
ublished on 09 e is licensed un sGicnyarngnetehanbeteotCimcshereeemenafficisitcntiioreynFn1s2icg2ya..sa9nTp.dhaHirsstoiecwvpueerlrvoaaeprlrle,yarttpayhppeplhilctaiaecstcaihbohnlniegischtaoollifgtchhthhetaeisaldlserpneeeglaceectcststiroooonff- 2Tadm.uh5ce.itrnseoBoaifaorcse-iudagansa1dr3n2co,u1ar3mng3aebnipneorrccolaudotdfuailcnyptsigooistnfee)n1at3ti5hatelhrssa1ot3uc4arcanensbdeovufisnepadrsostetoeip(nbrsyodpaurncode-
s Article. P This articl edalnueocctdtsrioc-fsrryeonamcthtieotthnicesrfesraoocmlutitoicnoansth,eoasdnpidcecriteahallecytitonhneecsse,esapsraaerrysaitgisonenipfaiocrfaatnthitoe.1n2p2rooIft- aaserveleacratinievtiyatytotrffaoicrntitsveuerbescsttairtnaatgleysscthinecmhlooiciwcaelcsoavnsicatehdneetyroaxatyirogenenscaaitpniaobannl.eEaonqfzuyehmoiguehss
s
ce was originally discovered as an electro-oxidation reaction,123 environment.Oneofthemainchallengesintheuseofamino
c
A
n
e
p
O
Fig.9 Kolbereactionsofdifferentsubstrates.
Thisjournalis©TheRoyalSocietyofChemistry2015 GreenChem.,2015,17,3231–3250 | 3239
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Perspective GreenChemistry
e.
c
n
e
c
Li
d
e
ort
p
n
U
0
3. Fig.10 Productionofsuccinonitrilefromglutamicacid.
M. cial
Amer
4 m
1
5:Co
1:0on acids is the ability to obtain pure amino acids for a synthetic 6 million tonnes.143 The reaction of methylglutamate to
1/2023 ution-N rfoorutpeo.tHenotwiaelvleyrs,ealescetinvzeymtraenssaforermsuatbisotnraitne mspiexceidfics,trtehaims sa,llaonwds 3an-cdyacnaotparlyotpicanaomicomunettshyolfesNtearBrreaqtui4re°sC3teoqugiivvaele7n0t%sofisNoalaOteCdl
on 1/1Attrib pteortiestnitcisa,lfsoerpeaxraamtiopnleabsyaderceasurbltoxoyflathtieonc.h1a36nged charge charac- tyhieelda,catinvdityproofcetehdesseviaisthsueffipcroiednutcttioondoecfa“rBbro+x”yleaqteuivgaluletnamceisc,
ded ons An alternative strategy in obtaining amino acids may be acid. This reaction is not within the bounds of Green Chem-
am
2015. DownloCreative Com sod[Lhbu-aotcaswtpiinonanertdthiocafuttashtcihenidigss]t)owmrpearilgclo-erddopueofrcrioegntdaeendinbis,mymcoycsaly.eancnoFuopolberhayccecatxinenarmi(bamep.1lu3pe7lrtoibIadtyrughcitnaehysdel-bfprpeoorelmoyn-- irhusesotqirwnuyegivraeesmrvalteanhnraigtsdeirfuoeamarmctcoioobuonrnloitnrmsegmoopmfaeiarnwoksaxesiistdneatfesosreraeslstatinananrgeedxappsecrenhonsldoizuvryecomepdpaetrriooaccxneirddossau,tst1hee4ess6
ss Article. Published on 09 April This article is licensed under a taabstcmpoitocnrrcrocoomdeuntdapahpmcoumrs,liomceududexobaleduaalfsrl,ctaneoejefmbqudwdoyusriit1anneiDn,trntgo4hgwSt-teiMdohnafidopcei.aanerirmAmdccoeseadsiiplnraicnulmbarooocebornbtptoxiautiploycdacetrlniiiaraoadnentdcstsiipehnio.udarnegcWonve.cdp4didhaa6auoq.ne1clcnuy31athb9mei,n4ohyeoAde-nyubDarrrdseoglirpnaoilofnyhmmfyilsliylaiontiisa-senxndeertod-euet4ccbc,doro,aaue6onnrsotnboca.(u1lSernoby3tntnx8eeaaoiytntrslfuIhiaayptsstttilahneee®irdddaees)- ophbnhampxeryoaaoidrpvidAtfcmereioemocaar.iabgrcdmilReeinletdneyeootncs(hpedaFpaenlrsieectgohotirso.dldo,oxyx1sxuy,wwi0igdcdvnai)eeaat.ern1htnett4iahvoaa8atnesedeoodindsuatx,aeenmiamtdcahraasoeecrt1xbih“vti0ooldhBe0onxlaer%ryyl+noyl”autpdstsaseeieauceorclnotbenaidxscovrittbifodritaovafyaPitxstgucey4yealsl5uattifh0ahnttoea-alagrbymsttavh3isbiacc-yceclaedidyanenaramncoenebi,gdoo1unee4upszn7uenryeosdmnptaipnzeneotayrdogsf---
e
cc to form beta-alanine by the use of aspartate alpha-decarboxy- suchasOleTJEhaveresultedintheenzymaticdecarbonylation
A
n lase, an intermediate that could be used for the synthesis of of stearic acid.149 They report a selectivity for 1-tridecene of
e
Op acrylamide.45 Other examples include the production of >90% from myristic acid and hydrogen peroxide at 28 °C for
gamma-amino butyric acid from glutamic acid by enzymatic 2 hours, with much of the byproduct being the beta-hydroxy
decarboxylation,44whichcanbeusedfortheproductionoffor alkane.
example N-methylpyrrolidone140 or N-vinyl pyrrolidone. The decarboxylation of amino acids can be performed
Phenylalaninecanbedeaminatedbytheuseofphenylalanine usingnon-metal basedorganocatalystsinaneffectiverouteto
ammonia lyase (PAL) to obtain cinnamic acid that is sub- the formation of amines. The first paper on this topic shows
sequently converted by deoxygenation to styrene by either amino acid transamination by the Strecker degradation,150
direct decarboxylation72 or to styrene and acrylic acid by where alloxan is used as an electron and ammonia acceptor,
ethenolysis.141 Other simple amines can be produced by the turningintothepurplemurexide.Strongelectrophilessuchas
decarboxylation of amino acids, such as ethanolamine from ninhydrin151 also promotes decarboxylation, but are so active
serine,orethylaminefromalanine.74 that amine hydrolysis is not possible and instead aldehydes
Amino acids also be oxidatively decarboxylated to form are produced. Pyridoxal is a cofactor in many decarboxylase
nitriles,usingNaOClandNaBrtoform3-cyanopropanoicacid, enzymes, but can also be used as a decarboxylation catalyst
and subsequently succinonitrile, from glutamic acid.142,143 capable of converting about 50 mol% of phenylglycine in
Nitrilessuchassuccinonitrileareusedmostlyfortheirability 30minutesat100°Cinwater.Ithastheissuethatitproduces
to be selectively hydrogenated to diamines for the production less than 50% yield of amines, preferring to transaminate
ofnylons.3-Cyanopropanoicacidcanbereadilyconvertedinto amino acids to aldehydes.152 Both the activity and selectivity
acrylonitrile, a monomeric starting compound for the pro- can be enhanced greatly by the use of an enzyme mimic to
duction of acrylonitrile-butadiene-styrene (ABS) and nitrile prevent amino acid hydrolysis.153 This can be as much as 16
butadiene rubber (NBR). Acrylonitrile can also dimerised to timesfasterforthedecarboxylationofphenylalanineinwater.
from adiponitrile,144 or hydrated to form acrylamide.145 As The same group goes on to show that they can perform selec-
such, the market scale for acrylonitrile reaches around tivetransaminativedecarboxylationusingthesamecatalyst.154
3240 | GreenChem.,2015,17,3231–3250 Thisjournalis©TheRoyalSocietyofChemistry2015