Grubbs catalysts

The Grubbs catalyst is a ruthenium - carbene - complex , which after its discoverer, Robert H. Grubbs was named and in the olefin metathesis applies.

There are two generations of the catalyst .

In contrast to other olefin metathesis catalysts, the Grubbs catalyst is insensitive to functional groups in the olefin and can be used in a wide range of solvents . For this reason, the catalyst is very versatile.

Grubbs catalysts

Grubbs catalysts
Surname	Grubbs I	Grubbs II
Structural formula
other names	Benzylidenebis (tricyclohexylphosphine) dichlororuthenium	Benzylidene [1,3-bis (2,4,6-trimethylphenyl) -2- imidazolidinylidene] dichloro (tricyclohexylphosphine) ruthenium
CAS number	172222-30-9	246047-72-3
Physical state	firmly	firmly
Molecular formula	C 43 H 72 Cl 2 P 2 Ru	C 46 H 65 Cl 2 N 2 PRu
Molar mass	822.96 g / mol	848.97 g / mol
Brief description	brown-pink solid	brown-pink solid
Melting point	153 ° C	143.5-148.5 ° C
GHS labeling	Caution	Caution
H and P phrases	315-319-335	228
	no EUH phrases	no EUH phrases
	261-305 + 351 + 338	210

First generation catalyst

The first generation of the catalyst was often used for ring-opening polymerization via metathesis (ROMP) and for ring-closing metathesis (especially to obtain large rings). The catalyst can be obtained in a simple manner from RuCl ₂ (PPh ₃ ) ₃ , phenyldiazomethane and tricyclohexylphosphine in a one-pot reaction. The Grubbs catalyst is relatively stable in air, which simplifies handling.

Second generation catalytic converter

The second generation of catalysts is used in the same reactions as the first generation, but has a much higher activity. The catalyst is stable to air and is made from the first generation catalyst and the alkoxy-protected 1,3-dimesityl-4,5-dihydroimidazol-2-ylidene. Both generations of the catalyst are commercially available.

In 2005 Robert H. Grubbs , Richard R. Schrock and Yves Chauvin were awarded the Nobel Prize for their discoveries about the catalyst and its application in olefin metathesis.

Hoveyda catalysts

The Hoveyda catalysts (also Grubbs-Hoveyda catalysts ) differ from the conventional Grubbs catalysts in one position. A tricyclohexylphosphine ligand was removed and the vacant coordination site was occupied by an aromatic ether derived from the carbene-bound residue.

Grubbs-Hoveyda catalysts
Surname	Grubbs-Hoveyda I	Grubbs-Hoveyda II
Structural formula	Cy =  cyclohexyl
other names	Dichloro ( o -isopropoxyphenylmethylene) (tricyclohexylphosphine) ruthenium (II)	1,3-bis (2,4,6-trimethylphenyl) -2-imidazolidinylidene) dichloro ( o -isopropoxyphenylmethylene) ruthenium
CAS number	203714-71-0	301224-40-8
Physical state	firmly	firmly
Molecular formula	C 28 H 45 Cl 2 OPRu	C 31 H 38 Cl 2 N 2 ORu
Molar mass	600.61 g / mol	626.62 g / mol
Brief description	brown solid	green solid
Melting point	195-197 ° C	216-220 ° C
GHS labeling	no GHS pictograms	no GHS pictograms
H and P phrases	no H-phrases	no H-phrases
	no EUH phrases	no EUH phrases
	no P-phrases	no P-phrases

Individual evidence

1. ^ Grubbs RH: Handbook of Metathesis . Wiley-VCH, Germany, 2003 .
2. ^ Grubbs RH, Trnka ™: Ruthenium-Catalyzed Olefin Metathesis . in Ruthenium in Organic Synthesis (S.-I. Murahashi, Ed.), Wiley-VCH, Germany, 2004 ( doi: 10.1002 / 3527603832.ch6 ).
3. ↑ Trnka, TM; Grubbs, RH: The Development of L ₂ X ₂ Ru = CHR Olefin Metathesis Catalysts: An Organometallic Success Story . In: Accounts of Chemical Research . 34, No. 1, 2001, pp. 18-29. doi : 10.1021 / ar000114f .
4. ↑ ^{a b c} Datasheet Grubbs Catalyst, 1st Generation at Sigma-Aldrich , accessed on January 28, 2017 ( PDF ).
5. ↑ ^{a b c} Datasheet Grubbs Catalyst, 2nd Generation at Sigma-Aldrich , accessed on January 28, 2017 ( PDF ).
6. ↑ Scholl, M .; Ding, S .; Lee, CW; Grubbs, RH: Synthesis and Activity of a New Generation of Ruthenium-Based Olefin Metathesis Catalysts Coordinated with 1,3-Dimesityl-4,5-dihydroimidazol-2-ylidene Ligands . In: Organic Letters . 1, No. 6, 1999, pp. 953-956. doi : 10.1021 / ol990909q .
7. ↑ Schwab, P .; Grubbs, RH; Ziller, JW: Synthesis and Applications of RuCl ₂ (= CHR ') (PR ₃ ) ₂ : The Influence of the Alkylidene Moiety on Metathesis Activity . In: Journal of the American Chemical Society . 118, No. 1, 1996, pp. 100-110. doi : 10.1021 / ja952676d .
8. ↑ This ligand is a nitrogen carbene (NHC) and the ruthenium is coordinated between the two carbene groups.
9. ↑ ^{a b c} data sheet Hoveyda-Grubbs Catalyst 1st Generation from Sigma-Aldrich , accessed on May 3, 2011 ( PDF ).
10. ↑ ^{a b c} data sheet Hoveyda-Grubbs Catalyst 2nd Generation at Sigma-Aldrich , accessed on May 3, 2011 ( PDF ).

Web links

Commons : Olefin metathesis catalysts  - Collection of pictures, videos and audio files

• Grubbs' catalyst in ring-closing metathesis