Does Aspirin React with NaOH? | C9H8O4 + NaOH Reaction Explained

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Discussion Overview

The discussion centers around the reaction between aspirin (C9H8O4) and sodium hydroxide (NaOH), exploring whether this reaction occurs and what the products might be. Participants examine the chemical structure of aspirin, its functional groups, and the implications for its reactivity in a basic solution. The context includes homework-related inquiries and stoichiometric considerations.

Discussion Character

  • Homework-related
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants assert that the overall formula for aspirin is insufficient without considering its structure.
  • One participant suggests that aspirin reacts with NaOH to produce carbon dioxide, water, and hydrogen, but this claim is challenged.
  • Another participant emphasizes the importance of recognizing aspirin as acetylsalicylic acid for understanding its reactivity.
  • It is noted that aspirin contains a carboxyl group and an ester group, with the carboxyl group reacting as an acid.
  • Some participants discuss the concept of saponification and question whether it occurs at moderate conditions or requires more extreme conditions.
  • There is mention of the rapid hydrolysis of aspirin in basic solutions, which may affect titration results.
  • One participant explains the need for excess sodium hydroxide during titration to ensure complete reaction with aspirin.
  • Backtitration is suggested as a common method to analyze the reaction quantitatively.

Areas of Agreement / Disagreement

Participants express differing views on the specifics of the reaction and its products, with no consensus reached on the exact nature of the reaction between aspirin and NaOH. Some agree on the need for structural considerations, while others debate the conditions required for the reaction.

Contextual Notes

There are unresolved aspects regarding the reaction mechanism, the conditions necessary for saponification, and the implications for titration accuracy. Participants rely on various interpretations of aspirin's structure and reactivity.

tgt
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Homework Statement


Does this reaction occur?

Aspirin = C9H8O4 (numbers are meant to be subscripts)

Aspirin + NaOH => what?



The Attempt at a Solution



Aspirin + NaOH => 9 carbon dioxide + 4 water molecules + 9 hydrogens (i.e H2)
 
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No. You have to look at the structure of aspirin, using just overall formula will lead you nowhere.
 
tgt said:

Homework Statement


Does this reaction occur?

Aspirin = C9H8O4 (numbers are meant to be subscripts)

Aspirin + NaOH => what?



The Attempt at a Solution



Aspirin + NaOH => 9 carbon dioxide + 4 water molecules + 9 hydrogens (i.e H2)
The empirical formula for Aspirin is not exact enough; you want to know that Aspirin is acetyl salicylic acid. (or is it three separate words, "acetylsalicylic acid ?")
 
Read the wikipedia article, it clearly states what should happen when you put aspirin in NaOH solution.
 
Aspirin has got a carboxyl group -COOH and an ester group -CO-OCH3 (acetyl); the first function reacts as an acid and becomes -COO-, the second function overcomes saponification RCOOR' + OH– -> RCOO– + R'OH
 
lesieux said:
Aspirin has got a carboxyl group -COOH and an ester group -CO-OCH3 (acetyl); the first function reacts as an acid and becomes -COO-, the second function overcomes saponification RCOOR' + OH– -> RCOO– + R'OH

Would the saponification reaction be a much slower reaction, possibly relying on more extreme conditions other than moderate concentrations at room temperature?
 
Aspirin in basic solution hydrolises quite fast. Fast enough that it will at least partially hydrolise during standard titration with base, giving unreproducible results.
 
That is the reason for you need to use an excess of sodium hydroxide (at high temperature to ensure that all the aspirin reacts) to titrate aspirine and then, in a second step, titrate the excess of sodium hydroxide. But you will have to consider that one mol of aspirin reacted with two moles of base in your calculation.
 
  • #10
That's right, backtitration is the usual approach.
 

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