obiem 23-60, ethyl aceto- In contrast to the rapid reaction shown in Probiem 23-60, ethv] aceta acetate requires a temperature over 150 °C to undergo the same kind cleavage reaction. How can you explain the difference in reactivity? loem C. H3C CO2E Na+ -OEt 2 CH3CO2ET Ethanol, 150 °C H H

Organic Chemistry
9th Edition
ISBN:9781305080485
Author:John E. McMurry
Publisher:John E. McMurry
Chapter22: Carbonyl Alpha-substitution Reactions
Section22.SE: Something Extra
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### Problem 23-60
**Question:**
Ethyl dimethylacetoacetate reacts instantly at room temperature when treated with ethoxide ion to yield two products, ethyl acetate and ethyl 2-methylpropanoate. Propose a mechanism for this cleavage reaction.

**Reaction Diagram:**
```
          O
          ||
H3C      C      CO2Et
    |           |
H3C—C—C—CH3   +  Na+ —OEt  
              |             |
            Ethanol, 25°C 

yields  

         CH3CO2Et      +          CH3
                                    |
     CH3CHCO2Et
```

### Problem 23-61
**Question:**
In contrast to the rapid reaction shown in Problem 23-60, ethyl acetoacetate requires a temperature over 150°C to undergo the same kind of cleavage reaction. How can you explain the difference in reactivity?

**Reaction Diagram:**
```
         O
         ||
H3C     C      CO2Et
    |           |
H     C—C—CH3 +  Na+ —OEt
               |            |
              Ethanol, 150°C 

yields  

        2  CH3CO2Et
```

### Explanation:
- **Problem 23-60 Reaction:** Ethyl dimethylacetoacetate reacts with ethoxide ion in ethanol at 25°C, producing ethyl acetate and ethyl 2-methylpropanoate instantly.
- **Problem 23-61 Reaction:** Ethyl acetoacetate, however, requires a much higher temperature of 150°C to undergo a similar cleavage reaction, resulting in two molecules of ethyl acetate.

**Discussion Points:**
1. **Reactivity Differences:** The key distinction lies in the structural differences between ethyl dimethylacetoacetate and ethyl acetoacetate. The additional methyl group in ethyl dimethylacetoacetate stabilizes the transition state, making the reaction more favorable and requiring a lower activation energy.
2. **Temperature Requirements:** The higher temperature needed for ethyl acetoacetate indicates that its cleavage reaction has a higher activation energy. This suggests less stabilization in its transition state compared to ethyl dimethylacetoacetate.
Transcribed Image Text:### Problem 23-60 **Question:** Ethyl dimethylacetoacetate reacts instantly at room temperature when treated with ethoxide ion to yield two products, ethyl acetate and ethyl 2-methylpropanoate. Propose a mechanism for this cleavage reaction. **Reaction Diagram:** ``` O || H3C C CO2Et | | H3C—C—C—CH3 + Na+ —OEt | | Ethanol, 25°C yields CH3CO2Et + CH3 | CH3CHCO2Et ``` ### Problem 23-61 **Question:** In contrast to the rapid reaction shown in Problem 23-60, ethyl acetoacetate requires a temperature over 150°C to undergo the same kind of cleavage reaction. How can you explain the difference in reactivity? **Reaction Diagram:** ``` O || H3C C CO2Et | | H C—C—CH3 + Na+ —OEt | | Ethanol, 150°C yields 2 CH3CO2Et ``` ### Explanation: - **Problem 23-60 Reaction:** Ethyl dimethylacetoacetate reacts with ethoxide ion in ethanol at 25°C, producing ethyl acetate and ethyl 2-methylpropanoate instantly. - **Problem 23-61 Reaction:** Ethyl acetoacetate, however, requires a much higher temperature of 150°C to undergo a similar cleavage reaction, resulting in two molecules of ethyl acetate. **Discussion Points:** 1. **Reactivity Differences:** The key distinction lies in the structural differences between ethyl dimethylacetoacetate and ethyl acetoacetate. The additional methyl group in ethyl dimethylacetoacetate stabilizes the transition state, making the reaction more favorable and requiring a lower activation energy. 2. **Temperature Requirements:** The higher temperature needed for ethyl acetoacetate indicates that its cleavage reaction has a higher activation energy. This suggests less stabilization in its transition state compared to ethyl dimethylacetoacetate.
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ISBN:
9781305080485
Author:
John E. McMurry
Publisher:
Cengage Learning