Match the following:
Reaction Organo Metallic Catalyst 1. \(CH_2=C H_{2}+\frac{1}{2} O_{2} \rightarrow C H_{3}CHO\) i. $(Ph_3P)_3RhCl$ 2. \(C H_{3}OH+CO \rightarrow C H_{3}COOH\) ii. $Co_2(CO)_8$ 3. \(C H_{2}=C H_{2}+2CO+2 H_{2}O \rightarrow C H_{3}C H_{2}CHO\) iii. $[Rh(Co)_2I_2]^-$ 4.\(C H_{2}=C H_{2}+ H_{2} \rightarrow C H_{3}-C H_{3}\) iv. $[PdCl_4]^{2-}$
Choose the correct answer from the following:
Organometallic Catalysts: Matching Chemical Reactions
This question requires matching specific chemical reactions with their corresponding organometallic catalysts. Understanding the typical catalytic cycles for common organic transformations is key to solving this.
Reaction Analysis and Catalyst Identification
Reaction 1: Ethylene Oxidation to Acetaldehyde
The reaction \(CH_2=CH_2 + \frac{1}{2} O_2 \rightarrow CH_3CHO\) represents the oxidation of ethylene to acetaldehyde. This is a classic example of the Wacker process. The Wacker process traditionally uses a palladium(II) catalyst, often in the form of $[PdCl_4]^{2-}$.
Match: 1 - iv. $[PdCl_4]^{2-}$
Reaction 2: Methanol Carbonylation to Acetic Acid
The reaction \(CH_3OH + CO \rightarrow CH_3COOH\) is the carbonylation of methanol to produce acetic acid. This process is famously achieved via the Monsanto process, which employs a rhodium-based catalyst system, typically involving iodide promoters. The complex $[Rh(CO)_2I_2]^-$ is characteristic of the active species in this catalytic cycle.
Match: 2 - iii. $[Rh(Co)_2I_2]^-$
Reaction 3: Ethylene Hydroformylation
The reaction \(CH_2=CH_2 + 2CO + 2H_2O \rightarrow CH_3CH_2CHO\) describes the hydroformylation (or oxo synthesis) of ethylene to produce propanal. Hydroformylation reactions are commonly catalyzed by cobalt or rhodium carbonyl complexes. Cobalt tetracarbonyl dimer, $Co_2(CO)_8$, is a well-established catalyst for this transformation, especially in older industrial processes.
Match: 3 - ii. $Co_2(CO)_8$
Reaction 4: Ethylene Hydrogenation
The reaction \(CH_2=CH_2 + H_2 \rightarrow CH_3-CH_3\) is the hydrogenation of ethylene to ethane. This is a fundamental alkene hydrogenation reaction. While heterogeneous catalysts are common, homogeneous catalysts are also effective. Wilkinson's catalyst, $(Ph_3P)_3RhCl$, is a renowned organometallic complex used for the homogeneous hydrogenation of alkenes and alkynes.
Match: 4 - i. $(Ph_3P)_3RhCl$
Summary of Matches
Based on the analysis of each reaction and the typical catalysts involved, the correct matching is:
| Reaction | Catalyst |
|---|---|
| 1. \(CH_2=C H_{2}+\frac{1}{2} O_{2} \rightarrow C H_{3}CHO\) | iv. $[PdCl_4]^{2-}$ |
| 2. \(C H_{3}OH+CO \rightarrow C H_{3}COOH\) | iii. $[Rh(Co)_2I_2]^-$ |
| 3. \(C H_{2}=C H_{2}+2CO+2 H_{2}O \rightarrow C H_{3}C H_{2}CHO\) | ii. $Co_2(CO)_8$ |
| 4. \(C H_{2}=C H_{2}+ H_{2} \rightarrow C H_{3}-C H_{3}\) | i. $(Ph_3P)_3RhCl$ |
Conclusion
The correct combination derived from matching the reactions to their respective organometallic catalysts is 1-iv, 2-iii, 3-ii, 4-i.
Important Questions from Transition Elements and Inner Transition Elements
For the reaction of trans-[lrX(CO)(PPh3)2] (X = F, Cl, Br, I) with O2, correct order of variation of rate with X is
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The correct statement(s) is/are
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(a) Dissociation of 12 in atomic state
(b) Interaction of low-lying σ*-orbital of iodine with lone pair of O (solvent)
(c) Formation of a charge-transfer complex
