The Wilkinson Catalyst or RhCl(PPh3)2 is a highly active homogeneous catalyst used in organic synthesis, particularly for hydrogenation reactions. It consists of a rhodium complex with phosphine ligands.
| IUPAC Name | Chloridotris(triphenylphosphine)rhodium(I) |
| Molecular Formula | C54H45ClP3Rh |
| CAS Number | 14694-95-2 |
| Synonyms | Rhodium chloride triphenylphosphine complex, Wilkinson’s catalyst, RhCl(PPh3)3, Rhodium(I) chloride triphenylphosphine complex, Rhodium triphenylphosphine chloride, Rhodium triphenylphosphine chloride |
| InChI | InChI=1S/2C18H15P.2ClH.Rh/c21-4-10-16(11-5-1)19(17-12-6-2-7-13-17)18-14-8-3-9-15-18;;;/h21-15H;2*1H;/q;;;;+3/p-3 |
Wilkinson Catalyst Molar Mass
The molar mass of Wilkinson Catalyst, also known as RhCl(PPh3)2, is 925.08 g/mol. This value is derived from the sum of the atomic masses of the constituent elements of the complex, which include rhodium, chlorine, carbon, hydrogen, and phosphorus. The molar mass of Wilkinson Catalyst is an important parameter in determining the amount of catalyst needed for a particular reaction.
Wilkinson Catalyst Boiling Point
Wilkinson Catalyst is typically used as a homogeneous catalyst, and thus does not have a well-defined boiling point. However, its decomposition temperature is reported to be around 180°C. At higher temperatures, Wilkinson Catalyst can decompose and lose its catalytic activity.
Wilkinson Catalyst Melting Point
The melting point of Wilkinson Catalyst, also known as RhCl(PPh3)3, is approximately 207-209°C. This value can vary slightly depending on the purity of the catalyst and the method of measurement.
Wilkinson Catalyst Density g/ml
The density of Wilkinson Catalyst is reported to be around 1.4 g/mL. This value can also vary depending on the purity of the catalyst and the method of measurement.
Wilkinson Catalyst Molecular Weight
The molecular weight of Wilkinson Catalyst, also known as RhCl(PPh3)3, is 925.08 g/mol. This value is calculated by summing the atomic weights of the constituent atoms in the complex. The molecular weight is important in determining the stoichiometry of reactions involving the catalyst.
Wilkinson Catalyst Structure
The structure of Wilkinson Catalyst, or RhCl(PPh3)3, consists of a rhodium atom coordinated with three triphenylphosphine (PPh3) ligands and one chloride ion (Cl-). The complex has a square planar geometry, with the rhodium atom at the center and the four ligands arranged around it in a flat plane. The PPh3 ligands are important in stabilizing the complex and facilitating its reactivity in organic synthesis.
Wilkinson’s catalyst Formula
The formula of Wilkinson’s catalyst is RhCl(PPh3)3. This formula represents the stoichiometry of the complex, indicating that there is one rhodium atom, one chloride ion, and three triphenylphosphine ligands in the complex. The formula is important in determining the amount of catalyst needed for a particular reaction, as well as in calculating the theoretical yield of the product.
| Appearance | Dark red crystalline solid |
| Specific Gravity | 1.4 g/mL |
| Color | Dark red |
| Odor | Odorless |
| Molar Mass | 925.08 g/mol |
| Density | 1.4 g/mL |
| Melting Point | 207-209°C |
| Boiling Point | Decomposes at ~180°C |
| Flash Point | Not applicable |
| Water Solubility | Insoluble |
| Solubility | Soluble in organic solvents such as benzene, toluene, and chloroform |
| Vapour Pressure | Not applicable |
| Vapour Density | Not applicable |
| pKa | Not applicable |
| pH | Not applicable |
Note: The values presented in this table are approximate and may vary depending on the source of information.
Wilkinson’s catalyst Safety and Hazards
When working with Wilkinson’s catalyst, it is important to take appropriate safety precautions to avoid potential hazards. The complex is not considered to be highly toxic, but it should still be handled with care to prevent accidental ingestion or inhalation. Exposure to the eyes or skin should be avoided, and appropriate protective equipment, such as gloves and safety glasses, should be worn when handling the catalyst. In addition, Wilkinson’s catalyst should be stored in a cool, dry, and well-ventilated area, away from sources of heat or flame. Disposal of unused catalyst should be done in accordance with local regulations.
| Hazard Symbols | None assigned |
| Safety Description | S22: Do not breathe dust/fume/gas/mist/vapours/spray. S24/25: Avoid contact with skin and eyes. S36/37/39: Wear suitable protective clothing, gloves and eye/face protection. |
| UN IDs | Not applicable |
| HS Code | 28500090 |
| Hazard Class | Not applicable |
| Packing Group | Not applicable |
| Toxicity | Low toxicity; not considered highly toxic, but should still be handled with care to prevent accidental ingestion or inhalation |
Wilkinson’s catalyst Synthesis Methods
The commonly used method for synthesizing Wilkinson’s catalyst involves the treatment of rhodium(III) chloride hydrate with an excess of triphenylphosphine in refluxing ethanol. This method can be performed as follows:
First, dissolve rhodium(III) chloride hydrate in ethanol to form a solution. Next, add an excess of triphenylphosphine to the solution and reflux the mixture for several hours. Monitor the solution for the formation of the catalyst, which can be identified by a color change from yellow to red.
During the synthesis process, triphenylphosphine acts as both a ligand and a reducing agent. Three equivalents of triphenylphosphine coordinate with the rhodium atom to form a stable complex, while the fourth equivalent reduces the rhodium(III) to rhodium(I). As a result, the final product of the reaction is RhCl(PPh3)3, with three triphenylphosphine ligands attached to the rhodium center.
After completing the synthesis of Wilkinson Catalyst, one can isolate the catalyst by filtering the reaction mixture and washing it with ethanol and diethyl ether. The resulting solid is then dried under vacuum. It is essential to handle the catalyst with care to avoid exposure to air and moisture, which can compromise its purity and activity.
Overall, this method is a relatively simple and effective way to synthesize Wilkinson’s catalyst on a large scale.
Wilkinson’s catalyst Uses
Wilkinson’s catalyst finds versatile applications in organic synthesis.
- It is widely used for promoting the hydrogenation of unsaturated organic compounds such as alkenes and alkynes.
- The catalyst is crucial in hydroformylation, the process of converting alkenes to linear alcohols.
- Wilkinson’s catalyst is extensively used in the synthesis of pharmaceuticals, agrochemicals, and polymer materials.
- It can promote various reactions, including C-C and C-O bond formation, leading to the synthesis of complex organic molecules.
- The catalyst is often used in combination with other catalysts to achieve specific reaction outcomes.
The use of Wilkinson’s catalyst leads to more efficient and sustainable chemical processes. It can reduce waste generation and energy consumption, promoting sustainable chemistry practices.
Questions:
Wilkinson’s Catalyst Hybridisation
Wilkinson’s Catalyst (RhCl(PPh3)3) hybridization involves the central Rhodium atom undergoing hybridization to form chemical bonds with its surrounding atoms.
The Rhodium atom in Wilkinson’s Catalyst has a d8 electron configuration, meaning that it has 8 valence electrons available for chemical bonding. In the presence of three triphenylphosphine (PPh3) ligands and one chloride (Cl) ligand, the Rhodium atom forms a complex with a distorted square-planar geometry.
The hybridization of the Rhodium atom in Wilkinson’s Catalyst is sp3d2 hybridization. This means that the Rhodium atom uses five atomic orbitals, including one 4s orbital, three 4p orbitals, and one 4d orbital, to form five sp3d2 hybrid orbitals.
In Wilkinson’s catalyst, the central rhodium atom undergoes sp3d2 hybridization, resulting in five hybrid orbitals. One of these hybrid orbitals forms a sigma bond with the chloride ligand, while the remaining four hybrid orbitals form sigma bonds with the three triphenylphosphine ligands. Two of the 4d orbitals on the rhodium atom form pi bonds with the ligands, completing the coordination sphere.
Overall, the sp3d2 hybridization of the Rhodium atom in Wilkinson’s Catalyst allows for strong chemical bonding with its surrounding ligands, which is crucial for its effectiveness as a homogeneous catalyst in various organic reactions.
Wilkinson’s catalyst selectivity
Wilkinson’s catalyst is a highly selective catalyst that is often used in organic synthesis to achieve specific reaction outcomes. The catalyst exhibits high selectivity due to its unique electronic and steric properties, which allow it to discriminate between different types of reactants and intermediates.
In hydrogenation reactions, for example, Wilkinson’s catalyst has been shown to exhibit high selectivity for the reduction of C=C bonds in the presence of other functional groups, such as C=O and C≡C bonds. This selectivity arises from the electronic properties of the iridium ion, which allow it to preferentially interact with the C=C bond and promote its reduction.
Similarly, in hydroformylation reactions, Wilkinson’s catalyst exhibits selectivity for the formation of linear aldehydes, rather than branched or cyclic aldehydes. This selectivity arises from the steric properties of the ligands, which help to control the orientation of the reactants and intermediates during the reaction.
Wilkinson’s catalyst formula
The formula of Wilkinson’s catalyst is RhCl(PPh3)3, which represents the complex formed between the Rhodium (Rh) atom, one Chloride (Cl) ion, and three Triphenylphosphine (PPh3) ligands.
In the Wilkinson Catalyst, the Rhodium atom actively exhibits a +1 oxidation state and forms coordination bonds with the Chloride ion and three Triphenylphosphine ligands. The Chloride ion and Triphenylphosphine ligands function as electron donors and actively stabilize the complex by interacting with the Rhodium atom.
The Triphenylphosphine ligands consist of three phenyl rings attached to a central phosphorus atom, which is bonded to the Rhodium atom. These ligands play a crucial role in stabilizing the complex and influencing its reactivity in various organic reactions.
The overall formula of Wilkinson’s catalyst, RhCl(PPh3)3, indicates the stoichiometry of the complex and the nature of the ligands and central metal atom involved.