[heckindale]

Hello people, welcome to my first post! 

I was on PubChem, just researching ADHD medication; methylphenidate and methylphenidate hydrochloride, and I've got two questions I can't find the answer to:

• Why is there a hydrochloride salt variant?
• There are so many chemicals with the formula C14H20ClNO2, how do they control the structure during synthesis?

I genuinely appreciate any responses!
               

[wildfyr]

Hydrochloride salts are made to simplify purification, and because they are more soluble in water (like in your body).

Controlled molecular structure of such species is a whole field of science known as synthetic organic chemistry. Go down the wiki rabbit hole!

[heckindale]

Hydrochloride salts are made to simplify purification.

In what way does it simplify purification? Also, I don't quite understand how the HCl is associated with the main methylphenidate section; how or if it's attracted in anyway.

[hypervalent_iodine]

Hydrochloride salts are made to simplify purification.

In what way does it simplify purification? Also, I don't quite understand how the HCl is associated with the main methylphenidate section; how or if it's attracted in anyway.

By changing it from the non-charged species, which would likely have low water solubility, to the charged salt, which has much higher water solubility. If you look at the structure of methyl phenidate, you’ll see a nitrogen contained in the form of an amine. It has a lone pair of electrons, which it can use to attack electrophilic species. If you put it into a solution of HCl, it will form a bond to the H⁺, giving the nitrogen a +1 charge. That is balanced out by the Cl^- counter ion to give the HCl salt.

[heckindale]

That helps a lot, thank you, sir! 

[hypervalent_iodine]

That helps a lot, thank you, sir! 

Ma'am*

[heckindale]

I'm going to make a terrible scientist if I keep making assumptions like that