Chemical Forums
Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: earthnation112 on January 09, 2017, 12:31:00 PM
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Hi just wanted someone to go over a few organic chemistry questions I was given regarding Acetal formation, cyclic Acetal formation and enolate reactions, let me know if I’ve made any mistakes, it would be greatly appreciated:
A bit of information regarding the four questions:
1. For the first question, I used the formula given for converting acetals back to a ketone.
2. For the second question I was given the final product but just needed to add the reagent.
3. For the third question, I was told it would be a cyclic acetal.
4. The last question was testing my knowledge on enolate reactions, EAA-type reactions of β-keto esters, hydrolysis and decarboxylation, enone reactions, and 1,5-dicarbonyl formation and was told to work out the 3 final products.
I have uploaded the 4 questions including my attempted answers as one image file, I used chem draw to make the reactions but I wasn't able to find a way to insert them here without uploading them as an image.
Thanks
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4 is incorrect. How did you come up with this answer? Can you show your proposed mechanism for each step?
A giveaway is that the equation in your answer is not balanced: What do you propose happened to the phenyl group and how do you explain EtOH formation?
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4 is incorrect. How did you come up with this answer? Can you show your proposed mechanism for each step?
A giveaway is that the equation in your answer is not balanced: What do you propose happened to the phenyl group and how do you explain EtOH formation?
I have changed my approach to the question, and found an example in my notes where a similar reaction is shown and I followed it as a template to see if I could get the major organic product first, I have attached the template and my attempt.
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That's a good start - aqueous acid and heating will result in further reaction though.
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That's a good start - aqueous acid and heating will result in further reaction though.
Since this question mentions "This unseen question is testing your knowledge of enolate reactions, EAA-type reactions of β-keto esters, hydrolysis and decarboxylation, enone reactions, and 1,5-dicarbonyl formation"
I have found a reaction which I think might be the correct one to use after browsing my notes, so I'm assuming I just plug in my reaction and I would get the right answer, I have uploaded my new attempt, I have changed EtOH to MeOH.
Since I know my end product is going to be a 1,5-dicarbonyl what exactly happens to the benzene ring as it can’t just magically disappear into thin air?
If Im completly off the mark with my answer is there some sort of direction you can give me so I can read alot more about this topic before attempting to have another attempt, thank you.
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I'm assuming I just plug in my reaction and I would get the right answer
This approach will not get you far in organic chemistry. It might be enough to pass at an early stage in your studies, but you will have no chance when confronted by more complex systems with multiple functional groups later on. You need to understand the fundamental concepts of mechanism in order to succeed.
If Im completly off the mark with my answer is there some sort of direction you can give me so I can read alot more about this topic before attempting to have another attempt
You are off the mark. Your second attempt was the correct structure of the intermediate formed in step 2 though.
You are getting it wrong because you are not considering the mechanisms.
Start with the reaction in your notes: Look up the mechanisms of the reactions listed in the question and see if you can produce a full mechanistic rationale for that transformation. Once you have done this correctly, the reaction in the question will be very easy to solve.
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I'm assuming I just plug in my reaction and I would get the right answer
This approach will not get you far in organic chemistry. It might be enough to pass at an early stage in your studies, but you will have no chance when confronted by more complex systems with multiple functional groups later on. You need to understand the fundamental concepts of mechanism in order to succeed.
If Im completly off the mark with my answer is there some sort of direction you can give me so I can read alot more about this topic before attempting to have another attempt
You are off the mark. Your second attempt was the correct structure of the intermediate formed in step 2 though.
You are getting it wrong because you are not considering the mechanisms.
Start with the reaction in your notes: Look up the mechanisms of the reactions listed in the question and see if you can produce a full mechanistic rationale for that transformation. Once you have done this correctly, the reaction in the question will be very easy to solve.
Okay cheers for the useful input, I'm reading up on my notes and some help from the book "Organic Chemistry" by Jonathan Clayden, once I have understood the mechanisms more I will give it another attempt and update this thread. Thanks
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I'm a bit confused by 2 and 3. Have you written the structures properly? These aren't acetals, they're peroxides. Also, if the question is asking you for a reagent, giving a molecular formula as your answer is not sufficient.
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I'm a bit confused by 2 and 3. Have you written the structures properly? These aren't acetals, they're peroxides. Also, if the question is asking you for a reagent, giving a molecular formula as your answer is not sufficient.
Are you referring to questions 2 and 3?
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I'm a bit confused by 2 and 3. Have you written the structures properly? These aren't acetals, they're peroxides. Also, if the question is asking you for a reagent, giving a molecular formula as your answer is not sufficient.
Are you referring to questions 2 and 3?
Yes.