Chapter 20, Problem 20.5YT

Interpretation Introduction

(a)

Interpretation:

It is to be indicated whether the given conversions would be energetically favorable or unfavourable. Also, it is to be given if the reaction is likely to occur readily.

Concept introduction:

Nucleophilic acyl substitution describes a class of substitution reactions involving nucleophiles and acyl compounds. An acid derivative has a leaving group, which is substituted by a nucleophile. If the leaving group is more stable than the nucleophile (weaker in terms of basicity), then the reaction is energetically favorable and occurs readily. If the nucleophile is more stable than the leaving group, then the reaction is enegetically unfavorble and does not occur readilty. This can be explained on the basis of the stability ladder below:

An acyl substitution that converts an acid derivative from a higher rung on the stability ladder to one on a lower rung of the ladder is energetically favorable. An acyl substitution that converts an acid derivative from a lower rung on the stability ladder to one on a higher rung of the ladder is energetically unfavorable.

Answer to Problem 20.5YT

The given conversion would be energetically unfavourable, and the reaction does not occur readily.

Explanation of Solution

The given reaction is

This is an example of a nucleophilic acyl substitution reaction in which an anhydride is getting converted into an acyl chloride. An acid derivative has a leaving group, which is substituted by a nucleophile. If the leaving group is more stable than the nucleophile (weaker in terms of basicity), then the reaction is energetically favorable and occurs readily. If the nucleophile is more stable than the leaving group, then the reaction is enegetically unfavorble and does not occur readilty. This can be explained on the basis of the stability ladder below:

An acyl substitution that converts an acid derivative from a higher rung on the stability ladder to the one on a lower rung of the ladder is energetically favorable. An acyl substitution that converts an acid derivative from a lower rung on the stability ladder to one on a higher rung of the ladder is energetically unfavorable.

Referring to this chart, an acid chloride is from a lower rung while an acyl chloride is from a higher rung on the stability ladder. Thus, this reaction is energetically unfavorable and so does not occur readily.

Conclusion

Conversion of an acid derivative from a lower rung to higher rung on the stability ladder is energetically unfavourable, and the reaction does not occur readily.

Interpretation Introduction

(b)

Interpretation:

It is to be indicated whether the given conversions would be energetically favorable or unfavourable. Also, it is to be given if the reaction is likely to occur readily.

Concept introduction:

Nucleophilic acyl substitution describes a class of substitution reactions involving nucleophiles and acyl compounds. An acid derivative has a leaving group, which is substituted by a nucleophile. If the leaving group is more stable than the nucleophile (weaker in terms of basicity), then the reaction is energetically favorable and occurs readily. If the nucleophile is more stable than the leaving group, then the reaction is enegetically unfavorble and does not occur readilty. This can be explained on the basis of the stability ladder below:

An acyl substitution that converts an acid derivative from a higher rung on the stability ladder to one on a lower rung of the ladder is energetically favorable. An acyl substitution that converts an acid derivative from a lower rung on the stability ladder to one on a higher rung of the ladder is energetically unfavorable.

Answer to Problem 20.5YT

The given conversion would be energetically unfavourable, and it does not occur readily.

Explanation of Solution

The given reaction is

This is an example of a nucleophilic acyl substitution reaction in which an amide is getting converted into an ester. If the leaving group is more stable than the nucleophile (weaker in terms of basicity), then the reaction is energetically favorable and occurs readily. If the nucleophile is more stable than the leaving group, then the reaction is enegetically unfavorble and does not occur readilty. This can be explained on the basis of the stability ladder below:

An acyl substitution that converts an acid derivative from a higher rung on the stability ladder to one on a lower rung of the ladder is energetically favorable. An acyl substitution that converts an acid derivative from a lower rung on the stability ladder to one on a higher rung of the ladder is energetically unfavorable.

Referring to this chart, an amide is from a lower rung while an ester is from a higher rung on the stability ladder. Thus, this reaction is energetically unfavorable and so does not occur readily.

Conclusion

Conversion of an acid derivative from a lower rung to higher rung on the stability ladder is energetically unfavourable, and the reaction does not occur readily.

Interpretation Introduction

(c)

Interpretation:

It is to be indicated whether the given conversions would be energetically favorable or unfavourable. Also, it is to be given if the reaction is likely to occur readily.

Concept introduction:

Nucleophilic acyl substitution describes a class of substitution reactions involving nucleophiles and acyl compounds. An acid derivative has a leaving group, which is substituted by a nucleophile. If the leaving group is more stable than the nucleophile (weaker in terms of basicity), then the reaction is energetically favorable and occurs readily. If the nucleophile is more stable than the leaving group, then the reaction is enegetically unfavorble and does not occur readilty. This can be explained on the basis of the stability ladder below:

An acyl substitution that converts an acid derivative from a higher rung on the stability ladder to one on a lower rung of the ladder is energetically favorable. An acyl substitution that converts an acid derivative from a lower rung on the stability ladder to one on a higher rung of the ladder is energetically unfavorable.

Answer to Problem 20.5YT

The given conversion would be energetically unfavourable, and it does not occur readily.

Explanation of Solution

The given reaction is

This is an example of nucleophilic acyl substitution reaction in which an acid chloride is getting converted into an ester. If the leaving group is more stable than the nucleophile (weaker in terms of basicity), then the reaction is energetically favorable and occurs readily. If the nucleophile is more stable than the leaving group, then the reaction is enegetically unfavorble and does not occur readilty. This can be explained on the basis of the stability ladder below:

An acyl substitution that converts an acid derivative from a higher rung on the stability ladder to one on a lower rung of the ladder is energetically favorable. An acyl substitution that converts an acid derivative from a lower rung on the stability ladder to one on a higher rung of the ladder is energetically unfavorable.

Referring to this chart, an acid chloride is from a higher rung while an ester is from a lower rung on the stability ladder. Thus, this reaction is energetically favorable and occurs readily.

Conclusion

Conversion of an acid derivative from a higher rung to lower rung on the stability ladder is energetically favourable, and the reaction occurs readily.

Interpretation Introduction

(d)

Interpretation:

It is to be indicated whether the given conversions would be energetically favorable or unfavourable. Also, it is to be given if the reaction is likely to occur readily.

Concept introduction:

Nucleophilic acyl substitution describes a class of substitution reactions involving nucleophiles and acyl compounds. An acid derivative has a leaving group, which is substituted by a nucleophile. If the leaving group is more stable than the nucleophile (weaker in terms of basicity), then the reaction is energetically favorable and occurs readily. If the nucleophile is more stable than the leaving group, then the reaction is enegetically unfavorble and does not occur readilty. This can be explained on the basis of the stability ladder below:

An acyl substitution that converts an acid derivative from a higher rung on the stability ladder to one on a lower rung of the ladder is energetically favorable. An acyl substitution that converts an acid derivative from a lower rung on the stability ladder to one on a higher rung of the ladder is energetically unfavorable.

Answer to Problem 20.5YT

The given conversion would be energetically unfavourable, and it does not occur readily.

Explanation of Solution

The given reaction is

This is an example of a nucleophilic acyl substitution reaction in which an acid anhydride is getting converted into dicarboxylic acid. If the leaving group is more stable than the nucleophile (weaker in terms of basicity), then the reaction is energetically favorable and occurs readily. If the nucleophile is more stable than the leaving group, then the reaction is enegetically unfavorble and does not occur readilty. This can be explained on the basis of the stability ladder below:

An acyl substitution that converts an acid derivative from a higher rung on the stability ladder to one on a lower rung of the ladder is energetically favorable. An acyl substitution that converts an acid derivative from a lower rung on the stability ladder to one on a higher rung of the ladder is energetically unfavorable.

Referring to this chart, an acid anhydride is from a higher rung while a carboxylic acid is from a lower rung on the stability ladder. Thus, this reaction is energetically favorable and occurs readily.

Conclusion

Conversion of an acid derivative from a higher rung to lower rung on the stability ladder is energetically favourable, and the reaction occurs readily.