What Happens When NaOH is Added to Quinizarin?

[reising1]

Homework Statement

Given Qunizarin, and if we add NaOH, what would the resulting compound look like?

Homework Equations

Here is what quinizarin looks like: http://upload.wikimedia.org/wikipedia/commons/thumb/c/c9/Quinizarin.svg/620px-Quinizarin.svg.png

The Attempt at a Solution

I'm guessing there would be hydroxide groups on the left side of the compound now?

 

[Borek]

What about quinizarin acidity?

 

[reising1]

According to this website:
http://www.drugfuture.com/chemdata/quinizarin.html

the pKa is 9.51. So it's not very acidic. So, what does this mean in terms of my question?

 

[Borek]

Not very acidic, still a weak acid - mixed with a strong base.

 

[reising1]

If it's a strong base, it will accept protons.

So, the OH groups will deprotonate?

 

[Borek]

Producing salt.

Note - no idea what is the second pKa, so it is better to not be so sure both groups will be deprotonated.

 

[reising1]

Oh, so you think just one group would deprotonate?

 

[Borek]

Depends on pH.