22E - Organic Chemistry (Mcmurry)

Question

Predict the product(s) and provide the mechanism for each reaction below.

Step-by-Step Solution

Answer

The answers are reduced from the reactions.

Step 1: Product of the reaction

The product of the reaction is methyl-2-methylbutanoate.

Step 2: Mechanism of the reaction

Step 3: Explanation of the mechanism

LDA removes a proton from the adjacent carbon of the carbonyl group in methyl propanoate and forms a resonance stabilized anion.

Then the anion attacks the ethyl bromide and removes the bromide by an ${S^2}_N$substitution reaction which leads to the desired product.

 

Step 4: Conclusion

Hence the complete reaction is 

 

Step 5: (b) Product of the reaction

The product of the reaction is 2-phenylpropanenitrile.

Step 6: Mechanism of the reaction

Step 7: Explanation of the mechanism

LDA removes a proton from the adjacent carbon of carbonyl group in 2-phenylacetonitrile and forms a resonance stabilized anion.

Then the anion attacks the methyl bromide and removes the bromide by a S_N² substitution reaction which leads to the desired product.

 

Step 8: Conclusion

Hence the complete reaction is 

 

Step 9: (c) Product of the reaction

The product of the reaction is 4-methyl-5-phenyl-3-pentanone

Step 10: Mechanism of the reaction

Step 11: Explanation of the mechanism

LDA removes a proton from the adjacent carbon of carbonyl group in 3-pentanone and forms a resonance stabilized anion.

Then the anion attacks the benzyl bromide and removes the bromide by a S_N² substitution reaction which leads to the desired product.

Step 12: Conclusion

Hence the complete reaction is 

 

Step 13: (d) Product of the reaction

The product of the reaction is 2-methylbutanal.

Step 14: Mechanism of the reaction

Step 15: Explanation of the mechanism

LDA removes a proton from the adjacent carbon of carbonyl group in butanal and forms a resonance stabilized anion.

Then the anion attacks the ethyl iodide and removes the bromide by a S_N² substitution reaction, leading to the desired product.

 

Step 16: Conclusion

Hence the complete reaction is