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			'''Grubbs catalysts''' are a series of ]es used as ]s for ]. They are named after ], the chemist who supervised their synthesis. Several generations of the ] have also been developed.<ref>{{cite book | last = Grubbs | first = Robert H. | title = Handbook of Metathesis | publisher = Wiley-VCH | location = Weinheim | year = 2003 | isbn = 978-3-527-30616-9 | edition = 1st}}</ref><ref>{{cite encyclopedia|last1=Grubbs|first1=R. H.|pages=153–177|last2=Trnka|first2=T. M.|title=Ruthenium-Catalyzed Olefin Metathesis |doi=10.1002/3527603832.ch6|encyclopedia=Ruthenium in Organic Synthesis|editor-first=S.|editor-last=Murahashi|location=Weinheim|publisher=Wiley-VCH|date=2004|isbn=978-3-527-60383-1}}</ref> Grubbs catalysts tolerate many ] in the ] substrates, are air-tolerant, and are compatible with a wide range of solvents.<ref name=vougioukalakis>{{cite journal |last1=Vougioukalakis |first1=G. C. |last2=Grubbs|first2= R. H. |year=2010 |title=Ruthenium-Based Heterocyclic Carbene-Coordinated Olefin Metathesis Catalysts |journal=] |pmid=20000700 |volume=110 |issue=3 |pages=1746–1787 |doi=10.1021/cr9002424}}
			</ref><ref>{{cite journal|title=The Development of L<sub>2</sub>X<sub>2</sub>Ru=CHR Olefin Metathesis Catalysts: An Organometallic Success Story| last1 = Trnka | first1 = T. M. | last2 = Grubbs | first2 = R. H. |journal= ]| year=2001| volume=34| issue=1| pages= 18–29 | doi=10.1021/ar000114f | pmid=11170353}}</ref> For these reasons, Grubbs catalysts have become popular in ].<ref>{{cite book | title = Metathesis in Natural Product Synthesis: Strategies, Substrates and Catalysts | last1 = Cossy | first1 = Janine | last2 = Arseniyadis | first2 = Stellios | last3 = Meyer | first3 = Christophe | publisher = Wiley-VCH | location = Weinheim | year = 2010 | isbn = 978-3-527-32440-8 | edition = 1st}}</ref> Grubbs, together with ] and ], won the ] in recognition of their contributions to the development of olefin metathesis.
			==First-generation Grubbs catalyst==
	{{Chembox		{{Chembox
			|Verifiedfields = changed
	| verifiedrevid = 404730935
			|Watchedfields = changed
	| Name = 1st Generation Grubbs' Catalyst
			|verifiedrevid = 447372032
	| ImageFile = Grubbs Catalyst 1st Generation.svg
			|Name = First-generation Grubbs catalyst
	| ImageFile1 = Grubbs-1G-3D-balls.png
			|ImageFile = Grubbs Catalyst 1st Generation.svg
	| IUPACName =
			|ImageFile1 = Grubbs-1G-from-xtal-2010-3D-balls.png
	| OtherNames =
			|IUPACName = Benzylidene-bis(tricyclohexylphosphino)-dichlororuthenium
	| Section1 = {{Chembox Identifiers
			|OtherNames =
	| CASNo = 172222-30-9
			|Section1={{Chembox Identifiers
	| PubChem =
			|CASNo_Ref = {{cascite|correct|??}}
	| SMILES = }}
			|CASNo = 172222-30-9
	| Section2 = {{Chembox Properties
			|UNII_Ref = {{fdacite|correct|FDA}}
	| C=43|H=72|Cl=2|P=2|Ru=1
			|UNII = J7P585D3ZC
	| MolarMass =
			|PubChem = 86306055
	| Appearance = Purple solid
			|ChemSpiderID = 25071160
	| Density =
			|InChI=1S/C43H72P2.2ClH.Ru/c1-8-22-36(23-9-1)43(44(37-24-10-2-11-25-37,38-26-12-3-13-27-38)39-28-14-4-15-29-39)45(40-30-16-5-17-31-40,41-32-18-6-19-33-41)42-34-20-7-21-35-42;;;/h1,8-9,22-23,37-43H,2-7,10-21,24-35H2;2*1H;/q+2;;;+2/p-2
	| MeltingPtC = 153
			|InChIKey = NDDFAYQFCZRYDT-UHFFFAOYSA-L
	| BoilingPt =
			|SMILES = Cl(Cl)((C1CCCCC1)(C1CCCCC1)C1CCCCC1)((C1CCCCC1)(C1CCCCC1)C1CCCCC1)=Cc1ccccc1
	| Solubility = }}
	| Section3 = {{Chembox Hazards
	| MainHazards =
	| FlashPt =
	| Autoignition = }}
	}}		}}
			|Section2={{Chembox Properties
			|C=43 | H=72 | Cl=2 | P=2 | Ru=1
			|Appearance = Purple solid
			|MeltingPtC = 153
			|MeltingPt_notes = (decomposition)
			|Solubility =
			}}
			}}
			In the 1960s, ruthenium trichloride was found to catalyze olefin metathesis. Processes were commercialized based on these discoveries. These ill-defined but highly active homogeneous catalysts remain in industrial use.<ref name=KO/> The first well-defined ruthenium catalyst was reported in 1992.<ref>{{cite journal | last1 = Nguyen | first1 = S. T. | last2 = Johnson | first2 = L. K. | last3 = Grubbs | first3 = R. H. | last4 = Ziller | first4 = J. W. | title = Ring-opening metathesis polymerization (ROMP) of norbornene by a Group VIII carbene complex in protic media | journal = ] | volume = 114 | issue=10 | pages = 3974–3975 | year = 1992 | doi = 10.1021/ja00036a053| url = https://authors.library.caltech.edu/88217/2/ja00036a053_si_001.pdf}}</ref> It was prepared from RuCl<sub>2</sub>(PPh<sub>3</sub>)<sub>4</sub> and diphenylcyclopropene.
			]
			This initial ruthenium catalyst was followed in 1995 by what is now known as the first-generation Grubbs catalyst. It is synthesized from ], ], and ] in a ].<ref>{{cite journal | journal = ] | title = A Series of Well-Defined Metathesis Catalysts – Synthesis of and Its Reactions | volume = 34 | pages = 2039–2041 | issue = 18 | last1 = Schwab | first1 = P. | last2 = France | first2 = M. B. | last3 = Ziller | first3 = J. W. | last4 = Grubbs | first4 = R. H. | doi = 10.1002/anie.199520391| year = 1995}}</ref><ref name=schwab2>{{cite journal| title=Synthesis and Applications of RuCl<sub>2</sub>(=CHR′)(PR<sub>3</sub>)<sub>2</sub>: The Influence of the Alkylidene Moiety on Metathesis Activity | last1=Schwab|first1= P.|last2= Grubbs|first2= R. H.|last3= Ziller|first3= J. W. |journal=J. Am. Chem. Soc.| year=1996 |volume=118 |issue=1| pages=100–110| doi=10.1021/ja952676d}}</ref>
			]
			The first-generation Grubbs catalyst was the first well-defined Ru-based catalyst. It is also important as a precursor to all other Grubbs-type catalysts.
			==Second-generation Grubbs catalyst==
	{{Chembox		{{Chembox
	| Name = 2nd Generation Grubbs' Catalyst		|Name = Second-generation Grubbs catalyst
	| ImageFile = Grubbs Catalyst 2nd Generation.png		|ImageFile = Grubbs catalyst Gen2.svg
	| ImageFile1 = Grubbs-2G-3D-balls.png		|ImageFile1 = Grubbs-2G-from-xtal-2005-3D-balls.png
			|IUPACName = dichloro(phenylmethylene)(tricyclohexylphosphino)ruthenium
	| IUPACName =
			|Section1 = {{Chembox Identifiers
	| OtherNames =
			|CASNo = 246047-72-3
	| Section1 = {{Chembox Identifiers
			|PubChem = 11147261
	| CASNo = 246047-72-3
			|ChemSpiderID = 9322369
	| PubChem =
			|StdInChI=1S/C21H26N2.C18H33P.C7H6.2ClH.Ru/c1-14-9-16(3)20(17(4)10-14)22-7-8-23(13-22)21-18(5)11-15(2)12-19(21)6;1-4-10-16(11-5-1)19(17-12-6-2-7-13-17)18-14-8-3-9-15-18;1-7-5-3-2-4-6-7;;;/h9-12H,7-8H2,1-6H3;16-18H,1-15H2;1-6H;2*1H;/q;;;;;+2/p-2
	| SMILES = }}
			|StdInChIKey = FCDPQMAOJARMTG-UHFFFAOYSA-L
	| Section2 = {{Chembox Properties
			|SMILES = Cl(Cl)(0n(-c1c(C)cc(C)cc1C)CCn0-c1c(C)cc(C)cc1C)((C1CCCCC1)(C1CCCCC1)C1CCCCC1)=Cc1ccccc1
	| C=46|H=65|Cl=2|N=2|P=1|Ru=1
			}}
	| MolarMass =
			|Section2 = {{Chembox Properties
	| Appearance = Pinkish brown solid
			|C=46 | H=65 | Cl=2 | N=2 | P=1 | Ru=1
	| Density =
			|Appearance = Pinkish brown solid
	| MeltingPt = 143.5-148.5 °C
			|MeltingPtC = 143.5 to 148.5
	| BoilingPt =
			}}
	| Solubility = }}
	| Section3 = {{Chembox Hazards		|Section3 = {{Chembox Hazards
			|GHSPictograms = {{GHS02}}
	| MainHazards =
			|GHSSignalWord = Warning
	| FlashPt =
			|HPhrases = {{H-phrases|228}}
	| Autoignition = }}
			|PPhrases = {{P-phrases|210|240|241|280|378}}
			}}
	}}		}}
			The second-generation catalyst has the same uses in organic synthesis as the first generation catalyst, but generally with higher activity. This catalyst is stable toward ] and ], thus is easier to handle in laboratories.
	'''Grubbs' Catalyst''' is a ] named after ], the chemist who first synthesized it. There are two generations of the ], as shown on the right.<ref name=grubbs>Grubbs, R.H. ; Wiley-VCH, Germany, '''2003'''.</ref><ref name=grubbs2>Grubbs, R.H.; Trnka, T.M.: in "Ruthenium in Organic Synthesis" (S.-I. Murahashi, Ed.), Wiley-VCH, Germany, '''2004'''.</ref> In contrast to other ] catalysts, Grubbs' Catalysts tolerate other ] in the ] and are compatible with a wide range of solvents.<ref name=vougioukalakis>{{cite journal |last=Vougioukalakis |first=G. C. |coauthors=] |year=2010 |title=Ruthenium-Based Heterocyclic Carbene-Coordinated Olefin Metathesis Catalysts |journal=] |pmid=20000700 |volume=110 |issue=3 |pages=1746–1787 |doi=10.1021/cr9002424 }}
	</ref><ref name=trnka>{{cite journal|title=The Development of L<sub>2</sub>X<sub>2</sub>Ru=CHR Olefin Metathesis Catalysts: An Organometallic Success Story| author= Trnka, T. M.; Grubbs, R. H. |journal= ]| year=2001| volume=34| issue=1| pages= 18–29 | doi=10.1021/ar000114f | pmid=11170353}}</ref> For these reasons, Grubbs' Catalysts are extraordinarily versatile.
			Shortly before the discovery of the second-generation Grubbs catalyst, a very similar catalyst based on an unsaturated ''N''-heterocyclic carbene (1,3-bis(2,4,6-trimethylphenyl)imidazole) was reported independently by Nolan<ref>{{cite journal|title=Olefin Metathesis-Active Ruthenium Complexes Bearing a Nucleophilic Carbene Ligand | last1 = Huang | first1 = J.-K. | last2 = Stevens | first2 = E. D. | last3 = Nolan | first3 = S. P. | last4 = Petersen | first4 = J. L. | journal= J. Am. Chem. Soc. | year=1999 | volume=121 | issue=12 | pages=2674–2678 | doi=10.1021/ja9831352}}</ref> and Grubbs<ref>{{cite journal | journal = ] | year = 1999 | volume = 40 | issue = 12 | pages = 2247–2250 | title = Increased Ring Closing Metathesis Activity of Ruthenium-Based Olefin Metathesis Catalysts Coordinated with Imidazolin-2-ylidene Ligands | last1 = Scholl | first1 = M. | last2 = Trnka | first2 = T. M. | last3 = Morgan | first3 = J. P. | last4 = Grubbs | first4 = R. H. | doi = 10.1016/S0040-4039(99)00217-8}}</ref> in March 1999, and by Fürstner<ref>{{cite journal | journal = Tetrahedron Lett. | title = Ruthenium Carbene Complexes with Imidazolin-2-ylidene Ligands Allow the Formation of Tetrasubstituted Cycloalkenes by RCM | year = 1999 | volume = 40 | issue = 26 | pages = 4787–4790 | doi = 10.1016/S0040-4039(99)00919-3 | last1 = Ackermann | first1 = L. | last2 = Fürstner | first2 = A. | last3 = Weskamp | first3 = T. | last4 = Kohl | first4 = F. J. | last5 = Herrmann | first5 = W. A.}}</ref> in June of the same year. Shortly thereafter, in August 1999, Grubbs reported the second-generation catalyst, based on a saturated ''N''-heterocyclic carbene (]):<ref name=scholl>{{cite journal|title=Synthesis and Activity of a New Generation of Ruthenium-Based Olefin Metathesis Catalysts Coordinated with 1,3-Dimesityl-4,5-dihydroimidazol-2-ylidene Ligands|last1=Scholl|first1=M.|last2=Ding|first2= S.|last3= Lee|first3= C. W.|last4= Grubbs|first4= R. H. |journal=] |year=1999| volume=1 |issue=6| pages=953–956| doi=10.1021/ol990909q|pmid=10823227}}</ref>
	== First generation catalyst==
	The First Generation Catalyst is often used in ] to achieve ] (see below), ] (ROMP), acyclic diene metathesis polymerization (ADMET), and ]. It is easily synthesized from RuCl<sub>2</sub>(PPh<sub>3</sub>)<sub>3</sub>,<ref name=scholl>{{cite journal|title=Synthesis and Activity of a New Generation of Ruthenium-Based Olefin Metathesis Catalysts Coordinated with 1,3-Dimesityl-4,5-dihydroimidazol-2-ylidene Ligands|author=Scholl, M.; Ding, S.; Lee, C. W.; Grubbs, R. H. |journal=] |year=1999| volume=1 |issue=6| pages=953–956| doi=10.1021/ol990909q}}</ref> ], and ] in a ].<ref name=schwab>{{cite journal| title=Synthesis and Applications of RuCl<sub>2</sub>(=CHR')(PR<sub>3</sub>)<sub>2</sub>: The Influence of the Alkylidene Moiety on Metathesis Activity | author=Schwab, P.; Grubbs, R. H.; Ziller, J. W. |journal=]| year=1996 |volume=118 |issue=1| pages=100–110| doi=10.1021/ja952676d}}</ref> Grubbs' Catalyst is a relatively stable compound in air, which makes handling very easy. The ] name of the 1<sup>st</sup> Generation Catalyst is benzylidene-bis(tricyclohexylphosphine)dichlororuthenium.
			]
	] is a reaction between two molecules containing double bonds. The groups bonded to the carbon atoms of the double bond are exchanged between molecules, to produce two new molecules containing double bonds with swapped groups. Whether a ] or ] is formed in this type of reaction is determined by the orientation the molecules assume when they coordinate to the catalyst, as well as the ] of the ]s on the double bond of the newly forming molecule. Other catalysts are effective for this reaction, notably those developed by ] (]).
			In both the saturated and unsaturated cases a phosphine ] is replaced with an ] (NHC), which is characteristic of all second-generation-type catalysts.<ref name=vougioukalakis/>
	== Second generation catalyst==
	The Second Generation Catalyst has the same uses in organic synthesis as the First Generation Catalyst, but has a higher activity. This catalyst is stable toward ] and ], thus is easier to handle in the lab. A catalyst based on an '''unsaturated''' N-heterocyclic carbene (1,3-bis(2,4,6-trimethylphenyl)dihydroimidazole) was reported in March 1999 by Nolan's group.<ref name=huang>{{cite journal|title=Olefin Metathesis-Active Ruthenium Complexes Bearing a Nucleophilic Carbene Ligand|author=Jinkun Huang,, Edwin D. Stevens,, Steven P. Nolan,, and, Jeffrey L. Petersen|journal=] |year=1999| volume=121 |issue=12| pages=2674–2678 | doi=10.1021/ja9831352}}</ref> Grubbs' group reported a catalyst based on a saturated N-heterocyclic carbene (1,3-bis(2,4,6-trimethylphenyl)imidazolidine) later the same year <ref name=scholl/> (August 1999). One phosphine ] is replaced with an ] (NHC) and in this case ruthenium is coordinated to two carbene groups. The ] name of the Second Generation Catalyst is benzylidenedichloro(tricyclohexylphosphine)ruthenium. Both generations of the catalyst are commercially available.
			Both the first- and second-generation catalysts are commercially available, along with many derivatives of the second-generation catalyst.
	== Hoveyda-Grubbs Catalyst ==
	In the first generation ''']-Grubbs Catalyst''', one of the ] ligands is replaced by an isopropyloxy group attached to the benzene ring. Its second generation has the other phosphine ligand replaced by NHC.
			== Hoveyda–Grubbs catalysts ==
	In one study a water soluble Grubbs catalyst is prepared by attaching a ] chain to the ] group. The imidazolinium salt is deprotonated by ] (KHMDS) ''in situ'' to give the ], which displaces one phosphine ligand to give the modified ruthenium complex:<ref name=hong>{{cite journal|title=Highly Active Water-Soluble Olefin Metathesis Catalyst| author=Soon Hyeok Hong and Robert H. Grubbs|journal= ]| year=2006| volume=128|issue=11 |pages=3508–3509| doi=10.1021/ja058451c|pmid=16536510}}</ref>
			{{Chembox
			|Name = First-generation Hoveyda–Grubbs catalyst
			|ImageFile = Hoveyda-katalysator.svg
			|ImageSize = 140px
			|ImageFile1 = Hoveyda-Grubbs-catalyst-1st-gen 3D-balls.png
			|ImageSize1 = 220px
			|IUPACName = Dichloro(''o''-isopropoxyphenylmethylene)(tricyclohexylphosphine)ruthenium(II)
			|Section1={{Chembox Identifiers
			|CASNo = 203714-71-0
			|PubChem = 24880901
			|ChemSpiderID = 9116251
			|StdInChI=1S/C18H33P.C10H12O.2ClH.Ru/c1-4-10-16(11-5-1)19(17-12-6-2-7-13-17)18-14-8-3-9-15-18;1-8(2)11-10-7-5-4-6-9(10)3;;;/h16-18H,1-15H2;3-8H,1-2H3;2*1H;/q;;;;+2/p-2
			|StdInChIKey = KMKCJXPECJFQPQ-UHFFFAOYSA-L
			|SMILES = Cl2(Cl)((C1CCCCC1)(C1CCCCC1)C1CCCCC1)=Cc1ccccc12C(C)C
			}}
			|Section2={{Chembox Properties
			|C=28 | H=45 | Cl=2 | P=1 | O=1 | Ru=1
			|Appearance = Brown solid
			| MeltingPtC = 195 to 197
			}}
			|Section3={{Chembox Hazards
			|GHSPictograms = {{GHS02}}
			|GHSSignalWord = Warning
			|HPhrases = {{H-phrases|228}}
			|PPhrases = {{P-phrases|210|240|241|280|378}}
			}}
			}}
			{{Chembox
			|Name = Second-generation Hoveyda–Grubbs catalyst
			|ImageFile = Misplaced Pages-HoveydaGrubbsCatalysts.png
			|ImageFile1 = Hoveyda-Grubbs-catalyst-from-xtal-2007-3D-balls.png
			|IUPACName = dichloro(''o''-isopropoxyphenylmethylene)ruthenium
			|Section1={{Chembox Identifiers
			|CASNo = 301224-40-8
			|PubChem = 11763533
			|ChemSpiderID = 9938229
			|EC_number = 608-446-3
			|StdInChI=1S/C21H26N2.C10H12O.2ClH.Ru/c1-14-9-16(3)20(17(4)10-14)22-7-8-23(13-22)21-18(5)11-15(2)12-19(21)6;1-8(2)11-10-7-5-4-6-9(10)3;;;/h9-12H,7-8H2,1-6H3;3-8H,1-2H3;2*1H;/q;;;;+2/p-2
			|StdInChIKey = ZRPFJAPZDXQHSM-UHFFFAOYSA-L
			|SMILES = Cl2(Cl)(0n(-c1c(C)cc(C)cc1C)CCn0-c1c(C)cc(C)cc1C)=Cc1ccccc12C(C)C
			}}
			|Section2={{Chembox Properties
			|C=31 | H=38 | Cl=2 | N=2 | O=1 | Ru=1
			|Appearance = Green solid
			|MeltingPtC = 216 to 220
			}}
			}}
			In the '''Hoveyda–Grubbs catalysts''', the benzylidene ligands have a chelating ''ortho''-isopropoxy group attached to the benzene rings. The ''ortho''-isopropoxybenzylidene moiety is sometimes referred to as a Hoveyda chelate. The chelating oxygen atom replaces a ] ligand, which in the case of the 2nd generation catalyst, gives a completely phosphine-free structure. The 1st generation Hoveyda–Grubbs catalyst was reported in 1999 by ]'s group,<ref>{{cite journal|last1=Kingsbury|first1=Jason S.|last2=Harrity|first2=Joseph P. A. |last3=Bonitatebus|first3=Peter J. |last4= Hoveyda|first4= Amir H. |title=A Recyclable Ru-Based Metathesis Catalyst|journal=]|date=1999|volume=121|issue=4|pages=791–799|doi=10.1021/ja983222u}}</ref> and in the following year, the second-generation Hoveyda–Grubbs catalyst was described in nearly simultaneous publications by the Blechert<ref name=":0" /> and Hoveyda<ref name="2ndGenHoveyda" /> laboratories. ]'s name is not commonly included in the eponymous catalyst name. The Hoveyda–Grubbs catalysts, while more expensive and slower to initiate than the Grubbs catalyst from which they are derived, are popular because of their improved stability.<ref name=vougioukalakis/><ref>{{Cite journal |title=Hoveyda-Grubbs type complexes with ruthenium-pnictogen/halcogen/halogen coordination bond. Synthesis, catalytic activity, applications. |url=https://rcr.colab.ws/publications/10.59761/RCR5132 |access-date=2024-10-22 |journal=Russian Chemical Reviews |date=2024 |language=en |doi=10.59761/rcr5132 |last1=Antonova |first1=A. S. |last2=Zubkov |first2=F. I. |volume=93 |issue=8 |pages=RCR5132 }}</ref> By changing the steric and electronic properties of the chelate, the initiation rate of the catalyst can be modulated,<ref>{{cite journal|last1=Engle|first1=Keary M.|last2=Lu|first2=Gang|last3=Luo|first3=Shao-Xiong|last4=Henling|first4=Lawrence M.|last5=Takase|first5=Michael K.|last6=Liu|first6=Peng|last7=Houk|first7=K. N.|last8=Grubbs|first8=Robert H.|title=Origins of Initiation Rate Differences in Ruthenium Olefin Metathesis Catalysts Containing Chelating Benzylidenes|journal=Journal of the American Chemical Society|date=2015|volume=137|issue=17|pages=5782–5792|doi=10.1021/jacs.5b01144|pmid=25897653|url=https://resolver.caltech.edu/CaltechAUTHORS:20150428-085409439 }}</ref><ref>{{cite journal|last2=Engle|first2=Keary M.|last1=Luo|first1=Shao-Xiong|last3=Deng|first3=Xiaofei|last4=Hejl|first4=Andrew|last6=Henling|first6=Lawrence M.|last5=Takase|first5=Michael K.|last7=Liu|first7=Peng|last8=Houk|first8=K. N.|last9=Grubbs|first9=Robert H.|title=An Initiation Kinetics Prediction Model Enables Rational Design of Ruthenium Olefin Metathesis Catalysts Bearing Modified Chelating Benzylidenes|journal=]|date=2018|volume=8|issue=5|pages=4600–4611|doi=10.1021/acscatal.8b00843|pmid=32528741 |pmc=7289044}}</ref> such as in the ]. Hoveyda–Grubbs catalysts are easily formed from the corresponding Grubbs catalyst by the addition of the chelating ligand and the use of a phosphine scavenger like ]:<ref name=2ndGenHoveyda>{{cite journal | journal = Journal of the American Chemical Society | title = Efficient and Recyclable Monomeric and Dendritic Ru-Based Metathesis Catalysts | year = 2000 | volume = 122 | issue = 34 | pages = 8168–8179 | last1 = Garber | first1 = S. B. | last2 = Kingsbury | first2 = J. S. | last3 = Gray | first3 = B. L. | last4 = Hoveyda | first4 = A. H. | doi = 10.1021/ja001179g}}</ref>
	:]
			The second-generation Hoveyda–Grubbs catalysts can also be prepared from the 1st generation Hoveyda–Grubbs catalyst by the addition of the NHC:<ref name=":0">{{cite journal | journal = Tetrahedron Letters | title = Synthesis and metathesis reactions of phosphine-free dihydroimidazole carbene ruthenium complex | year = 2000 | volume = 41 | pages = 9973–9976 | issue = 51 | last1 = Gessler | first1 = S. | last2 = Randl | first2 = S. | last3 = Blechert | first3 = S. | doi = 10.1016/S0040-4039(00)01808-6}}</ref>
	This catalyst is used in the ] reaction in water of a diene carrying an ] group making it water-soluble as well.
			]
	:]
			]
	== Applications ==
	An interesting application of Grubbs' Catalyst is in the aerospace industry. A spaceship's ] is a necessarily very strong material, but over time microcracks in the structure can form. A new material, with potential application in the construction of spaceship hulls, contains Grubbs' Catalyst, as well as capsules of ], which can undergo ]. When a crack in the hull forms, the capsules are ruptured and come into contact with Grubbs' Catalyst, which ] dicyclopentadiene and seals the crack.<ref name=white>{{cite journal|author=S.R. White, N.R. Sottos, P.H. Geubelle, J.S. Moore, M.R. Kessler, S.R. Sriram, E.N. Brown, S. Viswanathan| doi=10.1038/35057232| journal=]|year= 2001 |volume= 409| pages= 794–797|title= Autonomic healing of polymer composites|pmid=11236987|issue=6822}}</ref>
			In one study published by Grubbs and Hong in 2006, a water-soluble Grubbs catalyst was prepared by attaching a ] chain to the ] group.<ref name=Grubbs-Hong2006>{{cite journal|title=Highly Active Water-Soluble Olefin Metathesis Catalyst|first1=Robert H. |last1=Grubbs|first2=Soon Hyeok|last2=Hong|journal= Journal of the American Chemical Society| year=2006| volume=128|issue=11 |pages=3508–3509| doi=10.1021/ja058451c|pmid=16536510| url=https://authors.library.caltech.edu/76728/2/ja058451csi20051213_124352.pdf}}</ref> This catalyst is used in the ] reaction in water of a diene carrying an ] group making it water-soluble as well.
	On October 5, 2005, ], ] and ] won the ] in recognition of their contributions to the development of this widely used process.
			]
			== Third-generation Grubbs catalyst (fast-initiating catalysts) ==
			The rate of the Grubbs catalyst can be altered by replacing the phosphine ligand with more labile ] ligands. By using ] the initiation rate is increased more than a millionfold.<ref>{{cite journal | last1 = Love | first1 = J. A. | last2 = Morgan | first2 = J. P. | last3 = Trnka | first3 = T. M. | last4 = Grubbs | first4 = R. H. | title = A Practical and Highly Active Ruthenium-Based Catalyst that Effects the Cross Metathesis of Acrylonitrile | journal = ] | year = 2002 | volume = 41 | issue = 21 | pages = 4035–4037 | doi = 10.1002/1521-3773(20021104)41:21<4035::AID-ANIE4035>3.0.CO;2-I| pmid = 12412073}}</ref> Both pyridine and 3-bromopyridine are commonly used, with the bromo- version 4.8 times more labile resulting in even faster rates.<ref>{{Cite journal|last1=Walsh|first1=Dylan J.|last2=Lau|first2=Sii Hong|last3=Hyatt|first3=Michael G.|last4=Guironnet|first4=Damien|date=2017-09-25|title=Kinetic Study of Living Ring-Opening Metathesis Polymerization with Third-Generation Grubbs Catalysts|journal=Journal of the American Chemical Society|language=EN|volume=139|issue=39|pages=13644–13647|doi=10.1021/jacs.7b08010|pmid=28944665}}</ref> The catalyst is traditionally isolated as a two pyridine complex, however one pyridine is lost upon dissolving and ] the ] center throughout any chemical reaction.
			:]
			The principal application of the fast-initiating catalysts is as initiators for ] (ROMP). Because of their usefulness in ROMP these catalysts are sometimes referred to as the 3rd generation Grubbs catalysts.<ref>{{cite journal | last1 = Leitgeb | first1 = Anita | last2 = Wappel | first2 = Julia | last3 = Slugovc | first3 = Christian | title = The ROMP toolbox upgraded | journal = Polymer | year = 2010 | volume = 51 | issue = 14 | pages = 2927–2946 | doi = 10.1016/j.polymer.2010.05.002 | doi-access = free}}</ref> The high ratio of the rate of initiation to the rate of propagation makes these catalysts useful in ], yielding polymers with low ].<ref>{{cite journal | last1 = Choi | first1 = T.-L. | last2 = Grubbs | first2 = R. H. | title = Controlled Living Ring-Opening-Metathesis Polymerization by a Fast-Initiating Ruthenium Catalyst | journal = Angewandte Chemie International Edition | year = 2003 | volume = 42 | issue = 15 | pages = 1743–1746 | doi = 10.1002/anie.200250632| pmid = 12707895}}</ref>
			== Applications ==
			Grubbs catalysts are of interest for ].<ref>{{Cite book |title=Olefin metathesis: theory and practice |date=2014 |publisher=Wiley |isbn=978-1-118-71156-9 |editor-last=Grela |editor-first=Karol |location=Hoboken, New Jersey}}</ref><ref>{{Cite journal |last=Matsuo |first=Takashi |date=March 2021 |title=Functionalization of Ruthenium Olefin-Metathesis Catalysts for Interdisciplinary Studies in Chemistry and Biology |journal=Catalysts |language=en |volume=11 |issue=3 |pages=359 |doi=10.3390/catal11030359 |doi-access=free |issn=2073-4344}}</ref> It is mainly applied to fine chemical synthesis. Large-scale commercial applications of olefin metathesis almost always employ heterogeneous catalysts or ill-defined systems based on ruthenium trichloride.<ref name=KO>{{cite encyclopedia|encyclopedia=Kirk-Othmer Encyclopedia of Chemical Technology|author=Lionel Delaude |author2=Alfred F. Noels |year=2005| doi=10.1002/0471238961.metanoel.a01|place=Weinheim|publisher=Wiley-VCH|isbn = 978-0-471-23896-6|chapter = Metathesis}}</ref>
	==References==		==References==
	{{Reflist}}		{{Reflist|30em}}
	<!-- # {{Note|Louie}} Louie, J.; Grubbs, R. H. . -->		<!-- # {{Note|Louie}} Louie, J.; Grubbs, R. H. . -->
	{{Ruthenium compounds}}		{{Ruthenium compounds}}
	{{DEFAULTSORT:Grubbs' Catalyst}}
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