What Happens When NaOH is Added to Quinizarin?

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Discussion Overview

The discussion revolves around the chemical interaction between quinizarin and sodium hydroxide (NaOH), focusing on the resulting compound and the implications of quinizarin's acidity. Participants explore the theoretical aspects of this reaction, including the potential formation of hydroxide groups and the deprotonation of quinizarin.

Discussion Character

  • Homework-related, Conceptual clarification, Debate/contested

Main Points Raised

  • One participant speculates that adding NaOH to quinizarin would result in hydroxide groups on the left side of the compound.
  • Another participant questions the acidity of quinizarin, noting its pKa value of 9.51, suggesting it is not very acidic.
  • Some participants discuss the implications of quinizarin being a weak acid when mixed with a strong base like NaOH.
  • There is a suggestion that the hydroxide groups may deprotonate quinizarin, but uncertainty remains about how many groups would actually be deprotonated.
  • One participant notes the lack of knowledge regarding the second pKa of quinizarin, indicating caution in assuming both groups will deprotonate.
  • Another participant states that the extent of deprotonation depends on the pH of the solution.

Areas of Agreement / Disagreement

Participants express differing views on the extent of deprotonation of quinizarin when reacted with NaOH, indicating that the discussion remains unresolved regarding how many hydroxide groups will be affected.

Contextual Notes

There is uncertainty regarding the second pKa of quinizarin, which may influence the deprotonation process. The discussion also highlights the dependence on pH for determining the outcome of the reaction.

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What about quinizarin acidity?
 
Not very acidic, still a weak acid - mixed with a strong base.
 
If it's a strong base, it will accept protons.

So, the OH groups will deprotonate?
 
Producing salt.

Note - no idea what is the second pKa, so it is better to not be so sure both groups will be deprotonated.
 
Oh, so you think just one group would deprotonate?
 
Depends on pH.
 

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