How Many Molecules Are Needed for the Grignard Reaction with a Carbonate?

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Discussion Overview

The discussion revolves around the number of molecules required for the Grignard reaction with a carbonate. Participants explore various aspects of the reaction, including the role of different functional groups and the implications of using anhydrides versus carbonates.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • Some participants suggest that 5 molecules are needed for the Grignard reaction, while others propose that 6 may be the correct answer, depending on the context of the reaction.
  • There is a discussion about the reactivity of terminal alkynes with Grignard reagents, with some participants affirming this point.
  • Concerns are raised about the existence of certain compounds, with one participant arguing that a hydroxyl and a nitro group on the same carbon would lead to disproportionation, making the compound in question non-existent.
  • Some participants question the relevance of ether cleavage in the context of the Grignard reaction, with one acknowledging a misunderstanding regarding Grignard reagents and ether.
  • There is a clarification that the reaction involves a carbonate rather than an anhydride, with suggestions to treat it similarly to an ester, leading to the conclusion that 3 molecules would be needed for the carbonate.

Areas of Agreement / Disagreement

Participants express multiple competing views regarding the number of molecules required for the Grignard reaction, and the discussion remains unresolved with no consensus reached.

Contextual Notes

There are limitations in the discussion regarding assumptions about the existence of certain compounds and the specific conditions under which the Grignard reaction is being considered.

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Homework Statement
Ho wmany molecules of grignard reagent are consumed by 1 molecule of following compound-:
The complete question is in attempt at a solution.
Relevant Equations
Grignard reagent
20190924_215349.jpg


According to me the answer should be 5.I don't have the answer.I thought that 2 molecules will be used in anhydride,1 molecule in alcohol,2 molecule in cyclic ether.Can somebody tell the answer.
 
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Terminal alkynes are acidic and can react with Grignard reagents as well.
 
Ygggdrasil said:
Terminal alkynes are acidic and can react with Grignard reagents as well.
thanks for the information.Is my rest of the things correct.If it is,I would give my answer as 6.Please tell if I am wrong.
 
Why ether cleavage?
 
I’ll also point out that a hydroxyl and a nitro group on the same carbon would disproportionate to HONO and a ketone. So the compound in question wouldn’t even exist in the first place.
 
TeethWhitener said:
Why ether cleavage?
Sorry,I forgot that grignard reagent does not react with ether.I have another doubt now.For anhydride we will take 3 or 2 molecules,because anhydride consumes 3 grignard reagent to reduce completely and 2 to reduce partially.I think we should report it as 3.
 
TeethWhitener said:
I’ll also point out that a hydroxyl and a nitro group on the same carbon would disproportionate to HONO and a ketone. So the compound in question wouldn’t even exist in the first place.
ok it may happens but here i just have to tell the no. of molecules.
 
Physics lover said:
ok it may happens but here i just have to tell the no. of molecules.
My point is that it appears impossible to answer the question as written because the molecule can’t exist. It’s like asking what would happen if you had an aqueous solution with a pH of 20. That isn’t how pH works. Or in your case, that isn’t how molecules work.
 
Also, you don’t have an anhydride; you have a carbonate. Treat it the same way you would treat an ester, and then repeat the process.
 
  • #10
TeethWhitener said:
Also, you don’t have an anhydride; you have a carbonate. Treat it the same way you would treat an ester, and then repeat the process.
Sorry that was a typo.The carbonate would need 3 molecules.
So the answer should be 5.Is it correct?
 

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