Explaining Mechanism of Glucose Pentaacetate Reaction

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Discussion Overview

The discussion revolves around the mechanism of the reaction between glucose and acetyl chloride to form glucose pentaacetate. Participants explore various aspects of the reaction mechanism, including the roles of different intermediates and the nature of the bonds formed in the product.

Discussion Character

  • Homework-related, Technical explanation, Debate/contested

Main Points Raised

  • One participant proposes that acetyl chloride splits into a positively charged group and chloride ion, which then reacts with the hydroxyl groups of glucose.
  • Another participant clarifies that the representation of -OOC- does not imply an O-O bond, but rather indicates a carbon bonded to both a double-bonded oxygen and a singly bonded oxygen.
  • A participant questions the correctness of the initial mechanism proposed, seeking validation.
  • One participant suggests a preference for a nucleophilic attack on the acid chloride instead of the acylium ion mechanism initially proposed.
  • Another participant requests an explanation for the preference for nucleophilic attack over the proposed acylium ion mechanism.
  • One participant expresses skepticism about the stability of the ion pair intermediate suggested in the initial mechanism, noting that similar intermediates may exist in the presence of certain metal chlorides.

Areas of Agreement / Disagreement

Participants express differing views on the proposed mechanisms, with no consensus reached on the correct pathway for the reaction. There are competing models regarding the stability of intermediates and the nature of the attack on the acid chloride.

Contextual Notes

The discussion highlights limitations in the initial representation of the reaction mechanism and the need for clarity regarding the nature of the bonds in the product. There are unresolved questions about the stability of proposed intermediates and the validity of different mechanistic pathways.

nil1996
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Homework Statement



can anybody explain the mechanism of the reaction



C6H12O6 +CH3COCl → CHO(CHOOCCH3)4CH2OOCCH3

glucose + acetyl chloride → glucose pentaacetate

Homework Equations



none

The Attempt at a Solution


I am thinking that the CH3COCl will split as CH3C+O and Cl-.
Now these positively charged group will react with the five OH groups by displacing the hydrogens.

But i am not understanding how there is bond between O-O in glucose pentaacetate (which doesn't fit in my above mechanism.)
 
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This is just a limitation of linear representation of the structure. -OOC- does not mean a O-O bond, rather a carbon double bonded to an oxygen, and also singly bonded to a different oxygen.
 
Then is the mechanism correct?
 
I'd prefer nucleophilic attack on the acid chloride, rather than the acylium ion you have proposed.
 
can you explain why you are preferring the nucleophile attack?
 
I don't think the ion pair intermediate you've proposed is that stable, though I believe similar do exist in the presence of things like Fe or Al chlorides
 

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