Grubbs' Catalyst

Grubbs' Catalyst is named after the chemist by whom it was first synthesized, Robert H. Grubbs. There are two generations of the catalyst, as shown on the right. Both catalysts react preferentially with carbon-carbon double bonds, as opposed to other functional groups⁴. For this reason, Grubbs' Catalysts can be used in a variety of solvents and with numerous reactants.

The 1^st Generation Catalyst is often used in organic synthesis to achieve olefin cross-metathesis (see below), ring-opening metathesis polymerization (ROMP), and ring-closing metathesis². It is easily synthesized from RuCl₂(PPh₃)₃, phenyldiazomethane, and tricyclohexylphosphine in a one-pot synthesis¹. Grubbs' Catalyst is a relatively stable compound in air, which makes handling very easy. The IUPAC name of the 1^st Generation Catalyst is benzylidene-bis(tricyclohexylphosphine)dichlororuthenium.

The 2^nd Generation Catalyst has the same uses in organic synthesis as the 1^st Generation Catalyst, but has a higher activity. This catalyst is also air stable and is easily synthesized from the combination of the 1^st Generation Catalyst and alkoxy-protected 1,3-dimesityl-4,5-dihydroimidazol-2-ylidene³. The IUPAC name of the 2^nd Generation Catalyst is benzylidene[1,3-bis(2,4,6-trimethylphenyl)-2-imidazolidinylidene]dichloro(tricyclohexylphosphine)ruthenium. Both generations of the catalyst are commercially available through chemical companies such as Aldrich.

An interesting application of Grubbs' Catalyst is in the space industry. A spaceship's hull is a necessarily very strong material, but over time small microcracks in the structure can form. A new material used in the construction of spaceship hulls contains Grubbs' Catalyst, as well as capsules of a chemical called dicyclopentadiene (DCPD). When a crack in the hull forms, the capsules are ruptured and come into contact with Grubbs' Catalyst, which polymerizes DCPD and seals the crack⁵.

References

2. Organometallics, 2002, 21, 2153-2164.

3. Organic Letters, 1999, 1, 953-956.

4. Accounts of Chemical Research, 2001, 34, 18-29.

5. http://science.howstuffworks.com/self-healing-spacecraft1.htm