Why Does Sodium Hydroxide Increase Histidine's Solubility in Water?

[fdvet91]

Homework Statement

Histidine is an amino acid. It is not soluble in water but it will dissolve in water when dilute sodium hydroxide is added.

The question has two parts to it:
part-a)
Write an equation for the reaction that occurs between histidine and dilute sodium hydroxide.
part-b)
Explain why the solubility of the water changes after the sodium hydroxide is added

Homework Equations

we are also given the structure of histidine as shown in the link
http://imageshack.us/photo/my-images/580/histidine1.gif/

The Attempt at a Solution

i have no clue with equation work. i managed to get... C6H9N3O2 + NaOH >
cannot figure out what the product(s) is/are going to be
part-b)attempt
the ph will increase once NaOH is added but i don't see how that has anything to do with solubility. any help would be appreciated, thanks.

 

[Borek]

How does an acid react with a base?

 

[fdvet91]

an acid will react with a base to give salt and water

acid + base = salt +water
not sure what you mean by that though

 

[Borek]

Histidine is an aminoacid, isn't it?

 

[DeeNos]

Hello,

I would like to provide a response to the content you have provided. First, let's start with the equation for the reaction between histidine and dilute sodium hydroxide.

C6H9N3O2 + NaOH → C6H9N3O2Na + H2O

The product formed in this reaction is sodium histidine, which is soluble in water. This is why the solubility of histidine increases when dilute sodium hydroxide is added.

Now, let's discuss why the solubility of histidine increases with the addition of sodium hydroxide. This is due to the basic nature of sodium hydroxide. When it is added to water, it dissociates into sodium ions (Na+) and hydroxide ions (OH-). The hydroxide ions can react with the carboxylic acid group (-COOH) of histidine, forming a salt (C6H9N3O2Na) and water. This salt is more soluble in water compared to histidine, which is why the overall solubility of the solution increases.

I hope this explanation helps clarify the concepts for you. If you have any further questions, please don't hesitate to ask. Keep up the good work in your organic chemistry studies!