Grignard reaction product involving a ketone

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Discussion Overview

The discussion revolves around the Grignard reaction involving a ketone and its product, specifically focusing on the formation of an alcohol versus an alkene. Participants explore the mechanisms and steps involved in the reaction, including the role of sulfuric acid.

Discussion Character

  • Homework-related
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant describes their attempt at the Grignard reaction, producing an alcohol with specific substituents, and questions why the expected product is an alkene instead.
  • Another participant prompts consideration of "step 3" in the reaction mechanism, suggesting it may hold the key to understanding the product formation.
  • A participant speculates on the deprotonation of sulfuric acid and its role in producing both the alcohol and the alkene, expressing uncertainty about the correctness of this assumption.
  • Another reply suggests looking up "dehydration" and notes that sulfuric acid acts as a powerful desiccant, implying a connection to the reaction's outcome.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the mechanism or the reasons behind the formation of the alkene instead of the alcohol. Multiple viewpoints and uncertainties remain regarding the reaction steps and the role of sulfuric acid.

Contextual Notes

There are unresolved aspects regarding the specific steps of the Grignard reaction and the conditions under which the products are formed. The discussion reflects varying interpretations of the reaction mechanism and the influence of sulfuric acid.

chris_0101
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Homework Statement



Basically I have to show the product of this reaction:

Question.PNG




Homework Equations



Grignard reaction mechanism:
The conversion of a ketone to an alcohol

The Attempt at a Solution



My attempt of this reaction produces an alcohol with two ethyl groups attached to the central carbon as well as a phenyl group and an OH group attached to the central carbon, so the IUPAC name would be 3-phenyl-3-pentanol.

However, the answer is:
answer.PNG


Can someone please explain why the reaction produced an alkene instead of an alcohol. I do not know why this occurred and need some clarification. Also, when does this extra step occur.

Thanks.
 
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Think a little about step 3.
 
What occurs is step 3? I know that the H2SO4 is deprotonated to become HSO4. This produces the alcohol part of the compound, which is what I got. I am going to assume that deprotonation of HSO4 occurs, thus producing water and the alkene as shown in the answer. Is this right?
 
Look up "dehydration". Sulfuric acid is a powerful dessicant.
 

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