Grubbs Catalyst (CAS 172222-30-9): A Practical Guide to First-Generation Ruthenium Olefin Metathesis
Olefin metathesis — the redistribution of alkene fragments catalyzed by metal carbenes — earned the 2005 Nobel Prize in Chemistry for Chauvin, Grubbs, and Schrock, and it has since become a workhorse transformation in pharmaceutical process chemistry, natural product synthesis, and advanced materials. Among the catalysts that made this possible, the first-generation Grubbs catalyst, bis(tricyclohexylphosphine)benzylideneruthenium(IV) dichloride, remains one of the most widely used entry points into metathesis chemistry.
Its appeal is straightforward: the complex is tolerant of air and moisture at the bench scale, compatible with a broad range of functional groups, and commercially available at predictable quality. For sourcing teams supporting discovery and process groups, understanding what this catalyst can and cannot do — and what specifications matter — directly affects project timelines.
Chemical Identity and Key Properties
| Property | Value |
|---|---|
| CAS Number | 172222-30-9 |
| Molecular Formula | C43H74Cl2P2Ru+2 |
| Molecular Weight | 824.37 g/mol |
Catalyst Structure and the Metathesis Cycle
The first-generation Grubbs catalyst is a 16-electron ruthenium(II) benzylidene complex bearing two tricyclohexylphosphine ligands and two chlorides. The benzylidene unit is the propagating carbene that initiates the [2+2] cycloaddition/cycloreversion sequence with substrate alkenes. Phosphine dissociation generates the active 14-electron species, which is why phosphine scavengers such as copper(I) chloride frequently accelerate turnover.
Catalysts of this class proceed through the Chauvin mechanism: a metallacyclobutane intermediate fragments to release the exchanged alkene and a new metal carbene. Each turnover is mechanistically reversible, which is why removal of ethylene (for ring-closing metathesis) or excess of one partner (for cross-metathesis) drives conversions.
Where First-Generation Grubbs Catalyst Excels
Ring-Closing Metathesis (RCM)
Formation of five- to seven-membered rings — the sweet spot of this catalyst — including di- and trisubstituted cycloalkenes common in medicinal chemistry scaffolds. Macrocyclization is feasible when ethylene is removed by sparging or reduced pressure.
Cross-Metathesis (CM)
Terminal alkenes with electron-neutral or moderately electron-rich partners, including allylic alcohols and styrenes, react with useful selectivity when the partner is used in excess.
Functional-Group Tolerance
Esters, amides, alcohols, acids (with care), and many heterocycles survive the standard dichloromethane or toluene conditions — a decisive advantage over early molybdenum systems.
Known Limitations and When to Move to Second-Generation Systems
The first-generation catalyst is slower for sterically demanding or electron-poor alkenes and generally favors terminal over internal alkene reactivity. For trisubstituted olefins, hindered dienes, or cascade sequences, second-generation Grubbs and Hoveyda–Grubbs catalysts (bearing N-heterocyclic carbene ligands) deliver higher activity at lower loadings. Process chemists routinely screen first- and second-generation systems side by side during route scouting.
Handling, Stability, and Quality Control
The complex is supplied as a brown-to-purple crystalline solid and is stable for months when stored cool, dry, and under nitrogen in the dark. On the bench it tolerates brief air exposure during weighing, but stock solutions should be freshly prepared. Residual phosphine and ruthenium by-products are the main impurity concerns; suppliers who provide lot-specific purity by quantitative NMR or HPLC, consistent color, and reproducible activity simplify downstream analytical workload.
Frequently Asked Questions
What purity specifications should I expect for Grubbs catalyst?
Reputable suppliers provide purity by quantitative 1H NMR (typically ≥97%) and a defined appearance. Because minor oxidation products can silently consume catalyst activity, lot-to-lot consistency matters more than an extra decimal of stated purity.
How should Grubbs catalyst be stored on arrival?
Keep the solid in the original sealed container under nitrogen, protected from light, at 2–8 °C for long-term storage. Let the vial warm to room temperature before opening to avoid condensation.
Can CoreyChem supply Grubbs catalyst in bulk or with custom specifications?
Yes — CoreyChem supplies Grubbs catalyst from research quantities to multi-gram lots with COA and full analytical documentation, and can align packaging, purity thresholds, or labeling with your internal qualification requirements.
Source from CoreyChem
CoreyChem supplies Grubbs Catalyst (CAS 172222-30-9) with lot-specific COA and MSDS documentation. Custom synthesis, higher purity grades, and bulk packaging are available on request — contact our technical team with your target specification and quantity for current lead time and pricing.