Chapter 24, Problem 24.58P

Interpretation Introduction

(a)

Interpretation:

The organic product of the given reaction is to be drawn.

Concept introduction:

Multiple bonds in alkenes and alkynes are cleaved when treated with hot, concentrated permanganate in a basic solution in an oxidative cleavage reaction. Both carbons of the alkene or alkyne are oxidized in the process to carbonyl groups or carbon dioxide. The final functional group that is formed depends on the reaction conditions. The permanganate ion is added across the multiple bonds in a way similar to the Diels-Alder reaction, a $[4+2]$ cycloaddition. This is followed by a $[4+2]$ cycloelimination that breaks the $\text{C}-\text{C}$ bond, eliminating ${\text{MnO}}_{\text{2}}$. The two carbons are converted to carbonyl groups in this step. If these carbons have two alkyl groups bonded to them, they are converted to ketone groups. If only one alkyl group is present, the carbon is converted to an aldehyde. Aldehyde groups are further oxidized to the carboxylate group under the reaction conditions. This may be converted to a carboxylic acid by an acid workup. If there are no alkyl groups attached to the carbon, it is completely oxidized to carbon dioxide.

Answer to Problem 24.58P

The structure of the reactant in the given reaction is

Explanation of Solution

The given reaction is

Hot, concentrated permanganate (${\text{KMnO}}_4$) will cleave the double bond, oxidizing the two carbon atoms to carbonyl groups. This means the two carbonyl carbons in the product must have been joined by a double bond in the reactant.

Therefore, the structure of the reactant must be

Conclusion

The structure of the reactant was determined based on retrosynthetic analysis, the undoing of oxidative cleavage of a double bond.

Interpretation Introduction

(b)

Interpretation:

The organic product of the given reaction is to be drawn.

Concept introduction:

Multiple bonds in alkenes and alkynes are cleaved when treated with hot, concentrated permanganate in a basic solution in an oxidative cleavage reaction. Both carbons of the alkyne are oxidized in the process to carboxyl groups. The end carbon of a terminal alkyne is oxidized completely to carbon dioxide. The final functional group that is formed depends on the reaction conditions. The permanganate ion is added across the double bond in a way similar to the Diels-Alder reaction, a $[4+2]$ cycloaddition. This is followed by a $[4+2]$ cycloelimination that breaks the $\text{C}-\text{C}$ bond, eliminating ${\text{MnO}}_{\text{2}}$. The two carbons are converted to carbonyl groups in this step. If these carbons have two alkyl groups bonded to them, they are converted to ketone groups. If only one alkyl group is present, the carbon is converted to an aldehyde. Aldehyde groups are further oxidized to the carboxylate group under the reaction conditions. This may be converted to a carboxylic acid by an acid workup. If there are no alkyl groups attached to the carbon, it is completely oxidized to carbon dioxide.

Answer to Problem 24.58P

The structure of the reactant in the given reaction is

Explanation of Solution

The given reaction is

Hot, concentrated permanganate (${\text{KMnO}}_4$) will cleave the triple bond, oxidizing the two carbon atoms to carboxyl groups. Thus, the carbonyl carbon in the first product and that in carbon dioxide must have been joined by a double bond in the reactant. Further, carbon dioxide would have formed if one of the double bonded carbons was a terminal carbon.

Therefore, the structure of the reactant must be

Conclusion

The structure of the reactant was determined based on retrosynthetic analysis, the undoing of oxidative cleavage of a double bond.

Interpretation Introduction

(c)

Interpretation:

The organic product of the given reaction is to be drawn.

Concept introduction:

Multiple bonds in alkenes are cleaved when treated with ozone in a reaction called ozonolysis. Both carbons of the alkene are oxidized in the process to carbonyl groups. Ozone adds across the double bond in a $[4+2]$ cycloaddition step to form a molozonide with an $-\text{O}-\text{O}-\text{O}-$ bridge across the initial double-bonded carbons. The next two steps, a $[4+2]$ cycloelimination followed by another $[4+2]$ cycloaddition converts the molozonide to an ozonide, in which the alkene double bond is completely replaced, by one $-\text{O}-\text{O}-$ and one $-\text{O}-$ bridge. The final functional group that is formed depends on further processing. Reduction of the ozonide with $\text{Zn, HOAc}$ or ${{\text{(CH}}_{\text{3}}\text{)}}_{\text{2}}\text{S}$ results in the formation of a compound with ketone or aldehyde groups. Oxidation with ${\text{H}}_{\text{2}}{\text{O}}_{\text{2}}$ results in oxidizing the aldehyde group, if present, to a carboxylic acid.

Answer to Problem 24.58P

The structure of the reactant in the given reaction is

Explanation of Solution

The given reaction is

Ozonolysis will cleave the double bond in the reactant, oxidizing the two carbons to carbonyl groups. Therefore, the two carbonyl carbons in the products must have been joined by a double bond in the reactant.

Therefore, the structure of the reactant must be

Conclusion

The structure of the reactant was determined based on retrosynthetic analysis, the undoing of oxidative cleavage of a double bond.

Interpretation Introduction

(d)

Interpretation:

The organic product of the given reaction is to be drawn.

Concept introduction:

Multiple bonds in alkenes are cleaved when treated with ozone in a reaction called ozonolysis. Both carbons of the alkene are oxidized in the process to carbonyl groups. Ozone adds across the double bond in a $[4+2]$ cycloaddition step to form a molozonide with an $-\text{O}-\text{O}-\text{O}-$ bridge across the initial double-bonded carbons. The next two steps, a $[4+2]$ cycloelimination followed by another $[4+2]$ cycloaddition converts the molozonide to an ozonide, in which the alkene double bond is completely replaced, by one $-\text{O}-\text{O}-$ and one $-\text{O}-$ bridge. The final functional group that is formed depends on further processing. Reduction of the ozonide with $\text{Zn, HOAc}$ or ${{\text{(CH}}_{\text{3}}\text{)}}_{\text{2}}\text{S}$ results in the formation of a compound with ketone or aldehyde groups. Oxidation with ${\text{H}}_{\text{2}}{\text{O}}_{\text{2}}$ results in oxidizing the aldehyde group, if present, to a carboxylic acid.

Answer to Problem 24.58P

The structures of the reactant in the given reaction is

Explanation of Solution

The given reaction is

Ozonolysis will cleave a double bond in the reactant to oxidize the two carbons to carbonyl groups. If the product is an aldehyde, it is oxidized to the carboxylic acid group by ${\text{H}}_{\text{2}}{\text{O}}_{\text{2}}$. If the alkene is terminal, the end carbon is oxidized completely to carbon dioxide. The organic product of the reaction is a dicarboxylic acid, indicating the presence of a diene. This means the two carbonyl carbons each must have been doubly bonded to that from carbon dioxide.

Therefore, the structure of the reactant must be

Conclusion

The structure of the reactant was determined based on retrosynthetic analysis, the undoing of oxidative cleavage of a double bond.