Metathesis Catalyst Removal Techniques

Purification of a metathesis mixture can give you all sorts of problems (especially when using high catalyst loadings). Sometimes you need multiple columns to get a colorless product. Sometimes residual ruthenium can cause the product to isomerize during distillation or decompose over time. Numerous methods have been reported for the removal of metathesis catalysts after […]

1st Generation Grubbs Catalyst

1st Generation Grubbs Catalyst1 (Ph = phenyl; PCy3 = tricyclohexylphosphine) – CAS#: [172222-30-9] – FW: 822.95 – Color: Purple – Initiation temperature: >20 °C Process Strengths Weaknesses CM2 -Synthesis of 1,2-disubstituted olefins from terminal olefins-Ethenolysis of internal olefins to make terminal olefins-ADMET of unhindered terminal olefins -Formation of trisubstituted olefins-Electron-deficient substrates-Hindered substrates RCM -Synthesis of […]

Shell Higher Olefins Process

At over a million tons of capacity, the Shell Higher Olefins Process (SHOP) is one of the standards of industrial olefin metathesis chemistry. SHOP is remarkable in both its chemistry and process engineering. The process was developed for the conversion of ethylene to C10-C14 internal olefins (for conversion to linear primary detergent alcohols by hydroformylation), […]

Cross Metathesis

Cross metathesis (CM) is an attractive alternative to other olefination methods due to the large variety of commercially available olefin starting materials and to the high functional group tolerance of the ruthenium metathesis catalysts. Depending on the types of olefins involved in the metathesis reaction, cross metathesis reactions generally fall into one of three types: […]

Acyclic Diene Metathesis

Acyclic Diene Metathesis (ADMET) uses metathesis of terminal dienes to produce linear polymers and ethylene. Because ADMET is actually a variation on cross-metathesis, the process is reversible, and ethylene must be removed to drive the polymerization to completion. The polymers grow by step-growth kinetics (in contrast to the chain propagation kinetics of ROMP), so high-purity […]

Enyne Metathesis

Enyne metathesis is the reaction of an olefin and an alkyne to produce a 1,3-diene. When an alkyne is available to coordinate a ruthenium alkylidene, the reaction known as enyne metathesis can occur. The mechanism is analogous to an RCM reaction, but due to the added degree of unsaturation, the retro [2+2] reaction forms a […]

Asymmetric Metathesis

The first asymmetric Mo-based metathesis catalyst was reported by Grubbs way back in 1996 (J. Am. Chem. Soc. 1996, 118, 2499).  Since then, a large number of other chiral catalysts have been developed, based both on Ru and Mo (some structures shown below).  While Mo-based catalyst generally work better for RCM reactions, both Mo and […]

Ring-opening Metathesis Polymerization

Ring-opening metathesis polymerization (ROMP) uses metathesis catalysts to generate polymers from cyclic olefins. ROMP is most effective on strained cyclic olefins, because the relief of ring strain is a major driving force for the reaction – cyclooctene and norbornenes are excellent monomers for ROMP, but cyclohexene is very reluctant to form any significant amount of […]

Ring Closing Metathesis

If all goes well, I plan to write about Ring Closing Metathesis (RCM) quite a bit on this site, so I figured I needed a very broad RCM overview. Anyway, what kind of metathesis website would this be without the generic RCM scheme we’ve all seen a hundred times? The mechanism involves a first metathesis […]

Ruthenium Catalysts – 2nd Generation

The second revolution in ruthenium-catalyzed olefin metathesis was triggered by substituting one phosphine ligand in 1st generation catalysts with a more basic N-heterocyclic carbene (NHC). The activity of these 2nd generation (NHC-bearing) catalysts superseded that of 1st generation while maintaining functional group tolerance. The 2nd generation Grubbs catalyst (I) is undoubtedly the most well-known example […]

Ruthenium Catalysts – 1st Generation

Modern ruthenium based olefin catalysts encompass a range of complexes able to readily generate a 14 electron catalytic active species of the generic formula (L)(X2)Ru=CRR’ (L being a phosphine ligand in first generation catalysts). The first well-defined catalysts of this type, discovered by Grubbs in the early 90’s, feature a ruthenium metal center flanked with […]