What Are the Products of Reductive Ozonolysis of 1,4-Cyclohexadiene?

[Suraj M]

Homework Statement

What are the products formed on reductive ozonolysis of 1,4-cyclohexadiene?

Homework Equations

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The Attempt at a Solution

shouldn't it give propandial?? but the answer says that glyoxal is one of the products, how?

 

[AdityaDev]

yes. do you know its structure?
Also, propandial is not a product.

 

[Raghav Gupta]

Homework Statement

What are the products formed on reductive ozonolysis of 1,4-cyclohexadiene?

Homework Equations

[/B]

The Attempt at a Solution

shouldn't it give propandial?? but the answer says that glyoxal is one of the products, how?

What are the reductive work up conditions?
If you use zinc dust or DMS you will get aldehydes or ketones.
Use of H₂O₂ gives you carboxylic acids while sodium borohydride gives you alcohols.

 

[AdityaDev]

What are the reductive work up conditions?
If you use zinc dust or DMS you will get aldehydes or ketones.
Use of H₂O₂ gives you carboxylic acids while sodium borohydride gives you alcohols.

Yes. DMS takes an oxygen atom and gets converted to dimethyl sulphoxide. I think H₂O₂ gives nascent oxygen which oxidises the products.
Also, these compounds are also formed as minor products:

its unstable.
Also, if methanol is used as a solvent, then one more product will be formed. Try figuring it out.

 

[Raghav Gupta]

Also, if methanol is used as a solvent, then one more product will be formed. Try figuring it out.

In the ozonolysis process the methanol is used as a solvent with O₃ at -78°C to form ozonide. Using methanol is a necessary condition. We can then use any reagent to get aldehydes, ketones, alcohols or carboxylic acids.

You might be wanting to say that if methanol is not used then what is the product?
In that case we will not get ozonide.

 

[AdityaDev]

I think I used the wrong words. (Typo)? I will check my book and tell you the question later. But what I wanted to say is that, during the reaction, nucleophilic attack of methanol takes place on one of the intermediates To give a different compound.
[This was given by my chemistry teacher Last month.]

 

[AdityaDev]

Got it. Actually, this is the question. I was only able to remember some parts before.
Alcohols react with the carbonyl oxide to give hydroperoxy hemiacetals:

 

[Suraj M]

Hi you two, thanks for replying :).
the thing is, I just got into 12th, just finished, alcohols, phenols... i didn't understand a lot of what you guys said, my original question was this

I guess all the things you guys were talking about will be taught to me later(wont it? ) ,
could you help me solve this question for now? I selected answer D, which was correct because i thought it would give propandial and not glyoxal.. but the question says somethings else..
PS i hope you did well in your exams Aditya

 

[AdityaDev]

D gives 2 moles of a compound other than glyoxal. All others give only glyoxal on ozonolysis. Waite for a few months. Soon you will learn it.

 

[AdityaDev]

Exams did not go as planned. Atleast I can write jee advanced. The FIITJEE topper here scored 320 in mains.

 

[Raghav Gupta]

D gives 2 moles of a compound other than glyoxal. All others give only glyoxal on ozonolysis.

But the first option benzene gives H₂O₂ other then glyoxal, so why it is not the answer for question?

And how come 4th will give glyoxal? To me it is looking propanedial. Is there some rearrangement here that 4th option is giving glyoxal?

 

[AdityaDev]

Why H2O2? It gives three moles of glyoxal.
Also, propandial is not a proper name.

 

[Raghav Gupta]

Why H2O2? It gives three moles of glyoxal.
Also, propandial is not a proper name.

Sorry Benzene gives glyoxal as well as ZnO₂ in reductive work up.

Propanedial is a proper name, see
http://en.m.wikipedia.org/wiki/Malondialdehyde

 

[Raghav Gupta]

But the question remains unanswered, that are we getting propanedial in 1-4 cyclohexanediene?

 

[AdityaDev]

yes. 2 moles of propanedial.

 

[Raghav Gupta]

yes. 2 moles of propanedial.

And how glyoxal?

 

[AdityaDev]

question is wrong?

 

[Raghav Gupta]

question is wrong?

It may be right, some rearrangement can be possible.
Also benzene is giving glyoxal as well as ZnO2.
Is there a online calculator to see products?

 

[AdityaDev]

Why do you think rearrangement is possible?

 

[Raghav Gupta]

Why do you think rearrangement is possible?

What can the other reason be and how you can directly say question is wrong?
Earlier in some posts you were saying that propanedial is not a product.

In organic chem. there are many rearrangements. Reason could also be because of torsional strain but I am not sure.

Who can help three of us now?

 

[AdityaDev]

Thats because I got confused with the structure. I did not get the correct structure using google. @Borek can help us.

 

[Borek]

You need an organiker, not me.

 

[Raghav Gupta]

Now, I don't know a decent organiker here in PF.
Would this problem be solved?

 

[Suraj M]

Please Borek, or anyone else, could you help us out.
I don't understand how glyoxal could be a product from option D,
even by rearrangement how can you get glyoxal,

 

[AdityaDev]

Im sure. The question is wrong.

 

[Suraj M]

Ok then, if you're that sure,
thank you

 

[Raghav Gupta]

Ok then, if you're that sure,
thank you

Isn't something given in hints and solution section?

 

[Suraj M]

a friend gave me the question, when i asked for the solution, she said her friend asked her, don't know the exact source or the solution! sorry.
but what were you saying about rearrangement?

 

[Raghav Gupta]

a friend gave me the question, when i asked for the solution, she said her friend asked her, don't know the exact source or the solution! sorry.
but what were you saying about rearrangement?

The file you have attached was not of a book?
Rearrangement based on torsional strain and something but I am not sure.

 

[AdityaDev]

No rearrangement here. I am sure. Take chair form and do the mechanism.

 

[Raghav Gupta]

Okay I got all of the drama. All we were having were interpretation issues.

The question is correct and Suraj your answer D is correct.

The question is saying in which of the following glyoxal is not the only product.
All three of us might be thinking that the question is asking which of the following gives glyoxal as well as some other compound.
It is not like that.

It was a simple one and language confused us.
Clearly in D option we are getting propanedial the only product and not glyoxal.

This question was more of a language game then chemistry!

 

[AdityaDev]

yes.