fdnjj6 - 29-7-2020 at 18:05
I need to make mono nitrotoluene as a precursor for benzocaine.
The problem is that every fricking procedure I found always used concentrated nitric acid.
I have nitric acid that is probably 40-50% and contaminated with a small amount of what I assume is iron.
I have KNO3, NH4NO3, and NaNO3 as nitrate salts and plenty of 93% H2SO4 and some 98% lab grade H2SO4.
The issue is this: I don't know at what concentration mono nitrotoluene is able to form at a practical amount, and I don't know if the nitric acid
made in a nitrating bath is too strong and will start forming dinitrotoluene.
I can always dilute the acid mix and hope that the ions from the nitrate salt won't interfere with the reaction.
Also something I always wondered is how do you figure out how much acid you need for a nitration? I know the acids need to be in excess but when I
calculated the amount of sulfuric acid I needed for picric acid a while ago, it said that I needed a lot more sulfuric acid than what all procedures
gave. I calculated the moles of sulfuric acid needed to make sulfonated phenol, and then the sulfuric acid needed to react with the nitrate salt, and
then some left over to absorb water.
Whenever I see nitrations, instead of changing the amount of sulfuric acid when switching from pure nitric acid to a nitrate salt, the amount stays
the same.
How does that work??? Wouldn't you need more sulfuric acid to react with the nitrate salt and then the same amount of sulfuric acid needed as if you
just used nitric acid?
These things always perplexed me so if someone could help, that'd be great.
Nitrosio - 29-7-2020 at 21:19
Toluene / Acid (28% HNO3 / 56% H2SO4 / 16% H2O) = 1 : 2.5 @ 30-40 °C.
fdnjj6 - 30-7-2020 at 23:12
I have such a ratio already figured out sorry I should've mentioned that. I'll be keeping temps below 20 because I want as little dinitrotoluene to
form as possible. I'll be trying the synthesis I put together using what I assume is 50% acid. I'll titrate first and update the stoichiometry.