HCI D NaNH2 CH3-Br 2 eq H2/Pt В (a) CH3-CE CH - A C H2 E Lindlar

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Give the major organic product(s) for each step of the following reactions
### Reaction Scheme Explanation

In this reaction sequence, we begin with propyne, represented as CH₃-C≡CH. The reactions proceed as follows:

1. **Step 1**: The starting material, CH₃-C≡CH, undergoes a reaction with NaNH₂ to form compound **A**.
   
2. **Step 2**: Compound **A** reacts with CH₃-Br to form compound **B**.

3. **Step 3**: From compound **B**, there are three possible pathways:
   - **Pathway 1**: Treatment with HCl yields compound **D**.
   - **Pathway 2**: Reaction with 2 equivalents of H₂ in the presence of Pt (platinum catalyst) results in compound **C**.
   - **Pathway 3**: Reaction with H₂ in the presence of Lindlar's catalyst yields compound **E**.

### Detailed Description

- **NaNH₂ Reaction**: NaNH₂ is a strong base used for deprotonation in alkyne chemistry.
  
- **Alkylation with CH₃-Br**: The intermediate reacts with a methyl bromide source, CH₃-Br, facilitating the formation of a new carbon-carbon bond.

- **HCl Reaction**: The addition of HCl likely leads to the formation of a more saturated or modified product (compound D), possibly via an addition reaction.

- **Hydrogenation**:
  - **2 eq H₂/Pt**: This full hydrogenation pathway with two equivalents of hydrogen gas and a platinum catalyst completely reduces the structure (compound C).
  - **Lindlar Catalyst**: This semi-hydrogenation pathway allows for the selective reduction to a less saturated product (compound E), typical for converting alkynes into cis-alkenes.

This reaction scheme illustrates the versatility of alkyne chemistry in organic synthesis, showcasing pathways to various alkenes and alkanes through different reagents and conditions.
Transcribed Image Text:### Reaction Scheme Explanation In this reaction sequence, we begin with propyne, represented as CH₃-C≡CH. The reactions proceed as follows: 1. **Step 1**: The starting material, CH₃-C≡CH, undergoes a reaction with NaNH₂ to form compound **A**. 2. **Step 2**: Compound **A** reacts with CH₃-Br to form compound **B**. 3. **Step 3**: From compound **B**, there are three possible pathways: - **Pathway 1**: Treatment with HCl yields compound **D**. - **Pathway 2**: Reaction with 2 equivalents of H₂ in the presence of Pt (platinum catalyst) results in compound **C**. - **Pathway 3**: Reaction with H₂ in the presence of Lindlar's catalyst yields compound **E**. ### Detailed Description - **NaNH₂ Reaction**: NaNH₂ is a strong base used for deprotonation in alkyne chemistry. - **Alkylation with CH₃-Br**: The intermediate reacts with a methyl bromide source, CH₃-Br, facilitating the formation of a new carbon-carbon bond. - **HCl Reaction**: The addition of HCl likely leads to the formation of a more saturated or modified product (compound D), possibly via an addition reaction. - **Hydrogenation**: - **2 eq H₂/Pt**: This full hydrogenation pathway with two equivalents of hydrogen gas and a platinum catalyst completely reduces the structure (compound C). - **Lindlar Catalyst**: This semi-hydrogenation pathway allows for the selective reduction to a less saturated product (compound E), typical for converting alkynes into cis-alkenes. This reaction scheme illustrates the versatility of alkyne chemistry in organic synthesis, showcasing pathways to various alkenes and alkanes through different reagents and conditions.
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