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"Grubbs" redirects here. For the Supreme Court case of the same name, see United States v. Grubbs.

Robert H. Grubbs
Born	(1942-02-27)February 27, 1942 Possum Trot, Kentucky USA
Nationality	United States
Alma mater	University of Florida Columbia University
Known for	the development of the metathesis method in organic synthesis
Spouse	Helen O'Kane-Grubbs
Awards	Nobel Prize in Chemistry (2005)
Scientific career
Fields	Organic chemistry
Institutions	California Institute of Technology

Robert (Bob) Howard Grubbs (b. 27 February 1942 near Possum Trot, Kentucky) is an American chemist and Nobel laureate.

Early Life of Grubbs

Robert Grubbs was is reported to have been born in both Calvert City or Possum Trot, Kentucky. According to his official Nobel Laureate Autobiography some places, my birthplace is listed as Calvert City and in others Possum Trot. I was actually born between the two, so either one really is correct." Grubbs studied chemistry at the University of Florida (B.S. and M.S.), where he worked with Merle Battiste, and Columbia University, where he obtained his Ph.D. under Ronald Breslow in 1968.

Later Life of Grubbs

Grubbs was on the faculty at Michigan State University from 1969 to 1978 before becoming a professor at the California Institute of Technology. His main interests in organometallic chemistry and synthetic chemistry are catalysts, notably Grubbs catalyst for olefin metathesis and ring-opening metathesis polymerization with cyclic olefins such as norbornene. He also contributed to the development of so-called "living polymerization". Grubbs's many awards have included: Alfred P. Sloan Fellow (1974–76), Camille and Henry Dreyfus Teacher-Scholar Award (1975–78), Alexander von Humboldt Fellowship (1975), ACS Benjamin Franklin Medal in Chemistry (2000), ACS Herman F. Mark Polymer Chemistry Award (2000), ACS Herbert C. Brown Award for Creative Research in Synthetic Methods (2001), the Tolman Medal (2002), and the Nobel Prize in Chemistry (2005). He was elected to the National Academy of Sciences in 1989 and a fellowship in the American Academy of Arts and Sciences in 1994. He won the 2005 Nobel Prize in Chemistry with Richard Schrock and Yves Chauvin for development of the metathesis method in organic synthesis; metathesis is used in the development of pharmaceuticals and advanced polymeric materials. In metathesis reactions, double bonds between carbon atoms in molecules of different compounds are broken, splitting the molecules into atom groups; molecules of new compounds are formed when each group from one molecule forms a double bond with one of the groups from a different molecule. Two years after Schrock produced an efficient metal-compound catalyst for metathesis, Grubbs developed an improved catalyst that was stable in air.

Grubbs catalyst

Grubbs is responsible for the Grubbs catalyst, which carries his name. Grubbs catalysts are a series of transition metal carbene complexes used as catalysts for olefin metathesis. They are named after Robert H. Grubbs, the chemist who first synthesized them. There are two generations of the catalyst Both 1st and 2nd generation Grubbs catalysts involve organometallic structures around a ruthenium core.

1st generation Grubbs catalyst

The First Generation Catalyst is often used in organic synthesis to achieve olefin cross-metathesis (see below), ring-opening metathesis polymerization (ROMP), acyclic diene metathesis polymerization (ADMET), and ring-closing metathesis (RCM). It is easily synthesized from RuCl2(PPh3)3, phenyldiazomethane, and tricyclohexylphosphine in a one pot synthesis. Grubbs catalyst is a relatively stable compound in air, which makes handling very easy. The IUPAC name of the 1st Generation Catalyst is benzylidene-bis(tricyclohexylphosphine)dichlororuthenium.

1st generation Hoveyda–Grubbs catalyst

This catalyst is commonly known as the 1st Generation Hoveyda (or Hoveyda–Grubbs) catalyst. Generally, its activity is similar to that of the 1st Generation Grubbs Catalyst. This catalyst tends to be more stable than the bisphosphine Grubbs 1st Generation Catalyst in high temperature RCM reactions, and accordingly has found use in macrocyclization reactions to form disubstituted olefins.

2nd Generation Grubbs 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 moisture and air, 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.[7] Grubbs's group reported a catalyst based on a saturated N-heterocyclic carbene (1,3-bis(2,4,6-trimethylphenyl)imidazolidine) later the same year [5] (August 1999). One phosphine ligand is replaced with an N-heterocyclic[1]carbene (NHC) and in this case ruthenium is coordinated to two carbene groups. The IUPAC name of the Second Generation Catalyst is benzylidene[1,3- bis(2,4,6-trimethylphenyl)-2- imidazolidinylidene]dichloro(tricyclohexylphosphine)ruthenium. Both generations of the catalyst are commercially available.

2nd generation Hoveyda–Grubbs catalyst

Considered one of the best catalysts around for cross metathesis (CM) and ring closing metathesis (RCM), the Hoveyda–Grubbs catalyst works in most circumstances and is usually more reactive than the 2nd Generation Grubbs Catalyst at lower temperatures. It's useful for the efficient metathesis of electron-deficient substrates. This catalyst hasn't found much use in ring opening metathesis polymerization (ROMP) applications due in part to its cost. It is best made by starting from another metathesis catalyst, so it remains a high-price/high performance option for research labs

Applications of the catalyst

An interesting application of Grubbs catalyst is in the aerospace industry. A spaceship's hull 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 dicyclopentadiene, which can undergo ring[2]opening[3]metathesis[4]polymerisation. When a crack in the hull forms, the capsules are ruptured and come into contact with Grubbs catalyst, which polymerizes dicyclopentadiene and seals the crack.[9]

Ring-Closing Metathesis (RCM)

The Ring closing metathesis allows synthesis of 5 to 30 membered cyclic alkenes. The modern second generation Grubbs catalysts are more versatile. The key intermediate is a metallacyclobutane, which can undergo cycloreversion either towards products or back to starting materials. when the olefins of the substrate are terminal, the driving forces for RCM is the removal of ethene from the reaction mixture.

Ring-Opening Metathesis Polymerization (ROMP)

Ring opening polymerization involves opening and polymerizing a cyclic monomer to produce a linear polymer. Ring opening can proceed through a variety of mechanisms, depending on the monomer and the catalyst, and can yield a wide range of products. ROMP reaction is catalyzed primarily through the formation of metal-carbene. The initiation of the carbene species occurs through numerous pathways; solvent interaction, substituent interaction, and co-catalys all can contribute to the production of the reactive catalytic species. The third generation Grubbs catalyst was discovered in an effort to identify catalysts for acrylonitrile CM, but it turned out to be the fastest ruthenium catalysts known, measured to be >4,000 times faster to initiate than the 2nd generation Grubbs catalyst.

Grubbs catalyst cycles

1st stage

[2+2] cycloaddition reaction remember to keep the part of the molecule that you want to keep bound to the metal on the same side of the metal

2nd stage

Retro [2+2] cyclisation to give the metallo-carbenoid and the release of ethylene that drives the reaction forward

3rd stage

[2+2] cycloaddition of tethered or unconnected alkene

Final Stage

Catalyst regeneration and olefin or ring closing olefin formation

References

2nd gen catalyst- http://www.sigmaaldrich.com/catalog/product/aldrich/569747?lang=en&region=US

1st gen catalyst-http://www.sigmaaldrich.com/catalog/product/aldrich/579726?lang=en&region=US

1st gen hoveyda-http://www.sigmaaldrich.com/catalog/product/aldrich/577944?lang=en&region=US

2nd gen hoveyda-http://www.sigmaaldrich.com/catalog/product/aldrich/569755?lang=en&region=US

Uses of Catalysts

1. ‚Üë Grubbs, R.H. Handbook[5]of[6]Metathesis; Wiley-VCH, Germany, 2003.
2. ‚Üë Grubbs, R.H.; Trnka, T.M.: Ruthenium-Catalyzed[7]Olefin[8]Metathesis in "Ruthenium in Organic Synthesis" (S.-I. Murahashi, Ed.), Wiley-VCH, Germany, 2004.
3. ↑ Vougioukalakis, G. C.; Grubbs, R. H. (2010). "Ruthenium-Based Heterocyclic Carbene-Coordinated Olefin Metathesis Catalysts". Chem. Rev. 110 (3): 1746–1787.doi:10.1021/cr9002424. PMID 20000700.
4. ↑ Trnka, T. M.; Grubbs, R. H. (2001). "The Development of L2X2Ru=CHR Olefin Metathesis Catalysts: An Organometallic Success Story". Accounts[9]of[10]Chemical[11]Research 34 (1): 18–29.doi:10.1021/ar000114f.
5. ↑ 5.0 5.1 Scholl, M.; Ding, S.; Lee, C. W.; Grubbs, R. H. (1999). "Synthesis and Activity of a New Generation of Ruthenium-Based Olefin Metathesis Catalysts Coordinated with 1,3-Dimesityl-4,5-dihydroimidazol-2-ylidene Ligands". Organic[12]Letters 1 (6): 953–956.doi:10.1021/ol990909q.
6. ↑ Schwab, P.; Grubbs, R. H.; Ziller, J. W. (1996). "Synthesis and Applications of RuCl2(=CHR')(PR3)2: The Influence of the Alkylidene Moiety on Metathesis Activity". Journal[13]of[14]the[15]American[16]Chemical[17]Society 118 (1): 100–110. doi:10.1021/ja952676d.
7. ↑ Jinkun Huang,, Edwin D. Stevens,, Steven P. Nolan,, and, Jeffrey L. Petersen (1999). "Olefin Metathesis-Active Ruthenium Complexes Bearing a Nucleophilic Carbene Ligand". Journal[18]of[19]the[20]American[21]Chemical[22]Society 121 (12): 2674–2678. doi:10.1021/ja9831352.
8. ↑ Soon Hyeok Hong and Robert H. Grubbs (2006). "Highly Active Water-Soluble Olefin Metathesis Catalyst". Journal[23]of[24]the[25]American[26]Chemical[27]Society 128 (11): 3508–3509.doi:10.1021/ja058451c. PMID 16536510.
9. ↑ S.R. White, N.R. Sottos, P.H. Geubelle, J.S. Moore, M.R. Kessler, S.R. Sriram, E.N. Brown, S. Viswanathan (2001). "Autonomic healing of polymer composites". Nature 409 (6822): 794–797. doi:10.1038/35057232. PMID 11236987.

ROMP

Ivin, KJ. Ring-Opening Polymerization. 1. New York: Elsevier Science Publishing, 1984. 1-184. Print.