The spiro peroxide 13-A, which is readily prepared from...

Name: Problem 13, Chapter 11: Advanced Organic Chemistry. Part A. Structure and Mechanisms
Uploaded: 2021-09-30T14:10:04-08:00
Duration: 3 min 12 s
Channel: Nidhi Singhi
Description: The spiro peroxide 13-A, which is readily prepared from cyclohexanone and hydrogen peroxide, decomposes thermally to give substantial amounts of cyclodecane (13-B) and 11-undecanolactone (13-C). Account for the efficient formation of these macrocyclic compounds.

The spiro peroxide 13-A, which is readily prepared from cyclohexanone and hydrogen peroxide, decomposes thermally to give substantial amounts of cyclodecane (13-B) and 11-undecanolactone (13-C). Account for the efficient formation of these macrocyclic compounds.

Key Concepts

Macrocyclization

Macrocyclization involves the formation of large ring structures, often favored when reactive intermediates are poised correctly within a flexible molecular framework. In these processes, entropic and conformational factors come into play, facilitating the ring closure despite the typically low probability of forming large rings. The efficient formation of cyclodecane and lactone rings in the reaction is a good example of how intramolecular radical recombination can lead to the regeneration of stable macrocyclic compounds.

Intramolecular Radical Cyclization

Once radical fragments are formed, they can recombine via intramolecular processes. Radical cyclization, especially when forming larger ring systems or macrocycles, is facilitated by the proximity of radical centers within a molecule. This reaction pathway allows for the reorganization of connectivity to form new macrocyclic rings.

Spiro Peroxides

Spiro peroxides are cyclic peroxides in which the peroxide functionality is shared between two ring systems via a common spiro carbon. Their inherent structural strain and the weak O–O bond render them highly susceptible to various decomposition pathways when subjected to thermal or photolytic conditions.

Thermal Decomposition of Peroxides

The O–O bonds in peroxides are significantly weaker than typical C–C or C–H bonds, making them prone to homolytic cleavage under thermal conditions. This decomposition yields radical intermediates that initiate further transformations, often setting the stage for rearrangement and cyclization processes.

Radical Fragmentation Mechanism

Upon thermal cleavage of the weak peroxide bond, radicals generated can undergo fragmentation. This process breaks the ring system into reactive radical fragments that are predisposed to recombine or rearrange. These radical fragmentation pathways are central to the efficient formation of macrocyclic structures.

Transcript

00:01 Students in this question we have to find out which of the following statement are correct.

00:04 Okay, so a statement says that decomposition of hydrogen peroxide gives dry oxygen.

00:10 Okay, so if i write the reaction of decomposition of hydrogen peroxide, so yeah, it gives the water and the oxygen gas, right? so, a option is completely correct because it too gives die oxygen.

00:25 Now moving ahead, the b option b option says that, like, hydrogen peroxide compounds such as kclo3 pb and n .o3 when heated this liberate dioxygen.

00:39 So like if i show you, if i heat kclo3, then it will give kcl plus it will give dioxygen.

00:48 And for example if i heat pbno3 whole twice, sorry, pbno3, then also it will give pbo o plus b b b o plus it will give n o plus it will give oxygen okay to anode okay and the last one is n a n a 3 so i if i heed this one then it will give out na no 2 plus dioxide okay so the option is also correct option moving ahead checking option number c so it tells the then 2 ethyl enthracchinole is useful for the industrial preparation of hydrogen peroxide okay so 2 ethyl anthra canol when this is reacted with o2 in the presence of air okay and we also have used h2 and pd then it will give us 2 ethyl anthracanone okay so it will give us this compound plus it will give us h2o.

02:12 Okay, so this option is also correct.

02:15 Now, because this compound is, these compounds are formed and it says that the, this, and two in high lengthenactanone is used for the industrial preparation of hydrogen peroxide.

02:26 So we can use this method for the preparation of hydrogen peroxide, right? so this is also correct option...

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